Challenges in implementing a Total Quality Management system in a Thesis Proposal

Challenges in implementing a Total Quality Management system in a culturally diversified workforce - Thesis Proposal Example The research proposal critically analyzes the problems faced by management in implementing Total Quality Management for better services and concludes on the efficient steps that top management can take (Perry & Heron, 2003). Total Quality Management (TQM) is an essential business strategy which creates and embeds awareness of quality in the institutional process of implementing its duties. It is the organization-wide management of quality and it encompasses planning, organizing, control and assurance. It is the concern of many organizations to ensure that the services they offer are of high quality to satisfy the stakeholders. Quality of products is the basis of TQM. The approach is centered on the quality as a way forward of realizing long term success through customer success (Perry & Heron, 2003). What are the effects of cultural diversity on implementation of Total Quality Management (TQM) process? What are the challenges that organizations face in implementing TQM in culturally diversified workforce? The questions of the research proposal are very paramount and interesting since the research will be driven by the questions. The questions guide the researcher especially when collecting information or data to be used in ascertaining the actual impacts of cultural diversity on organizations. The research questions will act as the framework throughout the research work. When the researcher is out in the field, he will be using the questions to know whether they are collecting the right data. On the other hand, the questions are very relevant to the management of an organization because they use them to take corrective measures. Diversity in the workplace is a common phenomenon that has both negative and positive impacts on management and implementation of different operations in an organization. Past research conducted reveals that differences between different stakeholders impact the process of

Multi- Professional and Multi- agency working Essay Example for Free

Multi- Professional and Multi- agency working Essay â€Å"Multi-agency working brings together practitioners from different sectors and professions to provide an integrated way of working to support children, young people and families. † (DfES, 2001) In this essay my aim is to demonstrate an understanding of the collaborative skills required for effective multi professional practice. I will include feedback following a group presentation that I took part in and give my personal reflections of the process. I will then identify the issues and barriers in effecting multi professional practice linking to theory and legislation in Special Educational Needs (SEN) The Every Child Matters, (2004) agenda promotes effective multi- agency working and sharing of information between agencies, and Lord Laming stated that â€Å"effective support for children and families cannot be achieved by a single agency acting alone. It depends on a number of agencies working well together. † Multi- agency working is the involvement of more than one agency, and a team may consist of practitioners from several professional backgrounds who have different areas of expertise. Some of the practitioners may include health, education and social services. Some of these practitioners and professionals are involved in a child’s life are usually at least the child’s parents and the class teacher. This could then expand out to involve a speech therapist, a doctor, a social worker, a nurse and/or a psychologist. All of these people have an interest in helping to support the child and therefore all need to collaborate together for the benefit of the individual children. Speech and language therapists (SLT) are usually provided by the health services and provide formal assessment for pupils experiencing language and communication difficulties. They implement language and communication programmes with individuals and groups. They offer advice and support and assist with target setting and strategies According to Tassoni, (2003, p79) â€Å"the type of support that a child receives will depend on his or her need, but usually exercises and strategies are shared with everyone involved in the child’s care and education, especially parents† In my current role as a Speech and language therapy Assistant, (SLTA) I regularly liaise with the SLT and help to set some of the ndividual targets and provide appropriate resources to help the children to achieve their targets as well as implement programs set. As part of my role of a SLTA I work as part of a communication and learning team and have worked alongside many multi professionals, class teachers, learning support assistants, (LSA) in the school and a social worker. In the office in which I am based, each team member has their own individual skills and expertise that create a multi-skilled approach to support other team members, members of staff, students, parents and other professionals. The team consists of Teachers and Specialist Support Staff skilled in specific areas, SLT, an Occupational Therapists (OT) Early Years support worker and a Parent Support Advisor. As highlighted by the College of Occupational Therapists, (2011) Collaborative working within a multi-professional team can be the â€Å"most effective and efficient way to combine the skills of many professionals for the benefit of service users. †

Dc Power Source Utilization Engineering Essay

Dc Power Source Utilization Engineering Essay Many industrial applications have begun to require higher power apparatus in recent years. Some medium voltage motor drives and utility applications require medium voltage and megawatt power level. For a medium voltage grid, it is troublesome to connect only one power semiconductor switch directly. As a result, a multilevel power inverter structure has been introduced as an alternative in high power and medium voltage situations. A multilevel inverter is a power electronic device built to synthesize a desired AC voltage from several levels of DC voltages. The concept of multilevel converters has been introduced since 1975. The term multilevel began with the three-level converter. Subsequently, several multilevel converter topologies have been developed. Plentiful multilevel converter topologies have been proposed during the last two decades. Contemporary research has engaged novel converter topologies and unique modulation schemes. Moreover, there are three different major multilevel converter structures which are cascaded H-bridges converter with separate dc sources, diode clamped (neutral-clamped), and flying capacitors (capacitor clamped) [1] Although the diode clamped multilevel inverter is commonly discussed in the literature, there has been considerable interest in the series connected or cascaded H-bridge inverter topologies [2]. However, the elementary concept of a multilevel converter to achieve higher power is to use a series of power semiconductor switches with several lower voltage dc sources to perform the power conversio n by synthesizing a staircase voltage waveform. Capacitors, batteries, and renewable energy voltage sources can be used as the multiple dc voltage sources [1]. Multilevel power conversion has become increasingly popular in recent years due to advantages of high power quality waveforms, low electromagnetic compatibility (EMC) concerns, low switching losses, and high-voltage capability. The primary disadvantage of multilevel power conversion technology is the large number of semiconductor devices required. This does not yield a significant cost increase since lower-voltage devices may be used. However, an increase in gate drive circuitry and more elaborate mechanical layout are required [3]. Project Overview This project will involve in the design and construction of a single phase 3-level H-bridge inverter using the IGBTs. An H-bridge is an electronic circuit which enables a voltage to be applied across a load in either direction. These circuits allow DC motors to run forwards and backwards. H-bridges are available as integrated circuits, or can be built from discrete components. In this single phase H-bridge inverter circuit, the IGBTs are used as power devices that will be operated as a switch by applying control signal to gate terminal of IGBTs. The insulated gate bipolar transistor or IGBT is a three-terminal power semiconductor device, noted for high efficiency and fast switching. The software that will be used is MATLAB Simulink. Simulink is a commercial tool for modeling, simulating and analyzing multidomain dynamic systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries. The Aims and Objectives The aim of this project is to simulate a single phase 3-level H-bridge inverter (DC to AC converter) using the MATLAB Simulink and constructed it. The objectives of this project are as follows: To investigate the application of H-bridge inverter. To assemble using the software, circuits implementation, and troubleshoot for the hardware. To analyze the operation of the single-phase 3-level inverter for software and hardware. CHAPTER 2 LITERATURE REVIEW Inverter Power electronics converters may be classified into four categories based on the source and types of the desired output characteristics as shown in Figure 1.1 below: OUTPUT AC DC AC INPUTRECTIFIER REGULATORS DC CHOPPERS INVERTERS Figure 2.1: Converter Classification DC-to-AC converter is known as inverter. The function of an inverter is to change a DC input voltage to a symmetrical AC output voltage of desired magnitude and frequency. The variable output voltage could be fixed or variable at a fixed or variable frequency. Inverter can be built in many output phases which is normally use in practice like single phase inverter and three phase inverter. The implementation of the inverter circuit must to be involved in application of the power devices like SCR, MOSFET, IGBT, GTO, and Forced-Commutated Thyristor which is controlled to turning ON and turning-OFF in its operation as a converter. This inverter generally use PWM control signal for producing an AC output voltage [3]. Single Phase H-Bridge Inverter Operation The H-Bridge Inverter or sometimes called Full Bridge consists of four switches (see Figure 2.2). A boost converter is required as this system has no means of stepping up the input. Switches S1-S4, and S2-S3 make up two switch pairs. When S1and S4 are on, the output voltage is a positive pulse, and when S2 and S3 are on, the output is a negative pulse. The phase sequence, frequency, output magnitude and harmonics can be controlled through appropriate switching devices, in conjunction with other equipment. Figure 2.2: Single phase H-bridge inverter Single Phase Multilevel H-Bridges Inverter There are two types of multilevel H-bridge inverter that can be selected in this project which are separated dc source and single DC source. These two types have its pros and cons. The advantages of separated DC source are: The number of possible output voltage levels is more than twice the number of dc sources (m = 2s + 1). The series of H-bridges makes for modularized layout and packaging. This will enable the manufacturing process to be done more quickly and cheaply. while the disadvantage is: Separate dc sources are required for each of the H-bridges. This will limit its application to products that already have multiple SDCSs readily available. Each H-bridge cell requires an isolated dc source. The isolated sources are typically provided from a transformer/rectifier arrangement, but may be supplied from batteries, capacitors or photovoltaic arrays to add up the output voltages. This topology was patented by Robicon Group in 1996 and is one of the companies standard drive products.[2] On the other hand, for the single DC source multilevel H-bridge inverter, the advantage of this type of connection is only one DC supply is used. This will not limit its application to products. And the disadvantage of single DC source is transformer is needed to add up the output voltages Separated DC Source Multilevel H-Bridges Inverter A single-phase structure of an m-level cascaded inverter is illustrated in Figure 2.3. Each separate dc source (SDCS) is connected to a single-phase full-bridge, or H-bridge, inverter. Each inverter level can generate three different voltage outputs, +Vdc, 0, and -Vdc by connecting the dc source to the ac output by different combinations of the four switches, S1, S2, S3, and S4. To obtain +Vdc, switches S1 and S4 are turned on, whereas -Vdc can be obtained by turning on switches S2 and S3. By turning on S1 and S2 or S3 and S4, the output voltage is 0. The ac outputs of each of the different full-bridge inverter levels are connected in series such that the synthesized voltage waveform is the sum of the inverter outputs. The number of output phase voltage levels m in a cascade inverter is defined by m = 2s+1, where s is the number of separate dc sources [1]. Figure 2.3: Single-phase structure of a multilevel cascaded H-bridges inverter An example phase voltage waveform for a nine-level cascaded inverter and all H-bridge cell output waveforms are shown in Figure 2.4. In this thesis, all dc voltages are assumed to be equal. According to sinusoidal-liked waveform, each H-bridge output waveform must be quarter-symmetric as illustrated by V1 waveform in Figure 2.2. Obviously, no even harmonic components are available in such a waveform. To minimize THD, all switching angles must be numerically calculated. Figure 2.4: Waveform showing a nine-level output phase voltage and each H-bridge output voltage. One of the advantages of this structure is the number of possible output voltage levels is more than twice the number of dc sources (m = 2s + 1). The other advantage is the series of H-bridges makes for modularized layout and packaging. This will enable the manufacturing process to be done more quickly and cheaply. On the other hand, the main disadvantage of this topology is that separate dc sources are required for each of the H-bridges. This will limit its application to products that already have multiple SDCSs readily available. The sources are typically provided from a transformer/rectifier arrangement, but may be supplied from batteries, capacitors or photovoltaic arrays. Single DC source Multilevel H-Bridges Inverter Referred to Zhong Du1, Leon M. Tolbert, John N. Chiasson, and Burak ÃÆ'-zpineci thesis entitled A Cascade Multilevel Inverter Using a Single DC Source, a method is presented showing that a cascade multilevel inverter can be implemented using only a single DC power source and capacitors. Without requiring transformers, the scheme proposed allows the use of a single DC power source for examples a battery or a fuel cell stack while the remaining nà ¢Ã‹â€ Ã¢â‚¬â„¢1 DC sources being capacitors. Figure 2.5 shows the Single DC source Multilevel H-Bridges Inverter. The DC source for the first H-bridge (H1) is a DC power source with an output voltage of Vdc, while the DC source for the second H-bridge (H2) is a capacitor voltage to be held at Vdc/2. The output voltage of the first H-bridge is denoted by v1 and the output of the second H-bridge is denoted by v2 so that the output of this two DC source cascade multilevel inverter is v(t) = v1(t)+v2(t). By opening and closing the switches of H1 appropriately, the output voltage v1 can be made equal to à ¢Ã‹â€ Ã¢â‚¬â„¢Vdc, 0, or Vdc while the output voltage of H2 can be made equal to à ¢Ã‹â€ Ã¢â‚¬â„¢Vdc/2, 0, or Vdc/2 by opening and closing its switches appropriately. Figure 2.5: Single DC source Multilevel H-Bridges Inverter IGBTs Versus MOSFETs The power MOSFET is a device that is voltage- and not current-controlled. MOSFETs have a positive temperature coefficient, stopping thermal runaway. The on-state-resistance has no theoretical limit, hence on-state losses can be far lower. The MOSFET also has a body-drain diode, which is particularly useful in dealing with limited free wheeling currents. All these advantages and the comparative elimination of the current tail soon meant that the MOSFET became the device of choice for power switch designs. Then in the 1980s the IGBT came along. The IGBT combines the cross between the power MOSFET and a bipolar power transistor (see Figure 2.2). The IGBT has the output switching and conduction characteristics of a bipolar transistor but is voltage-controlled like a MOSFET. In general, this means it has the advantages of high-current handling capability of a bipolar with the ease of control of a MOSFET. However, the IGBT still has the disadvantages of a comparatively large current tail and no body drain diode. Early versions of the IGBT are also prone to latch up, but nowadays, this is pretty well eliminated. Another potential problem with some IGBT types is the negative temperature co-efficient, which could lead to thermal runaway and makes the paralleling of devices hard to effectively achieve. This problem is now being addressed in the latest generations of IGBTs that are based on non-punch through (NPT) technology. This technology has the same basic IGBT structure (see Figure 2.6) bu t is based on bulk-diffused silicon, rather than the epitaxial material that both IGBTs and MOSFETs have historically used [4]. Figure 2.6: NPT IGBT cross section The comparisons between MOSFETs and IGBTs are as below: Table 2.1: Comparisons between IGBTs and MOSFETs IGBTs MOSFETs Characteristics Low duty cycle Low frequency ( Narrow or small line or load variations High-voltage applications (>1000V) >5kW output power Operation at high junction temperature is allowed (>100 °C) Long duty cycles High frequency applications (>200kHz) Wide line or load variations Low-voltage applications ( Applications Motor control: Frequency Uninterruptible power supply (UPS): Constant load, typically low frequency Welding: High average current, low frequency ( Low-power lighting: Low frequency ( Switch mode power supplies (SMPS): Hard switching above 200kHz Switch mode power supplies (SMPS): ZVS below 1000 watts Battery charging [4] Applications of Inverters There are many application of inverter available today. Some of the applications are as follows: DC power source utilization An inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage. Grid tie inverters can feed energy back into the distribution network because they produce alternating current with the same wave shape and frequency as supplied by the distribution system. They can also switch off automatically in the event of a blackout. Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid. Electric vehicle drives Adjustable speed motor control inverters are currently used to power the traction motor in some electric locomotives and diesel-electric locomotives as well as some battery electric vehicles and hybrid electric highway vehicles such as the Toyota Prius. Various improvements in inverter technology are being developed specifically for electric vehicle applications. In vehicles with regenerative braking, the inverter also takes power from the motor (now acting as a generator) and stores it in the batteries. Uninterruptible power supplies An uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when main power is not available. When main power is restored, a rectifier is used to supply DC power to recharge the batteries. Variable-frequency drives A variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters. Induction heating Inverters convert low frequency main AC power to a higher frequency for use in induction heating. To do this, AC power is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power. CHAPTER 3 METHODOLOGY Introduction This chapter exposes the proposed method of this project to built single phase multilevel H-bridge inverter. This project can be divided into two main parts of study which are software and hardware implementation. For the software part, the software used is PIC24 Compiler that used to do the programming for the microcontroller part and MATLAB to do the simulation of the inverter circuit before implemented it in hardware. In addition, Proteus 7 Professional is also used to simulate the driver circuit before do the hardware. The summary of the project is shown in Figure 3.1. Software Part Prepared (Microcontroller) Hardware Part Prepared Troubleshooting Interfacing Result Figure 3.1: The project summary Design of the H-Bridge Inverter System The H-Bridge inverter system can be divided into three main stages that were constructed. It is consists of: Microcontroller Power electronics driver Power electronics inverter Each part was treated as a separate functional block system. Figure 3.2 below shows the block diagram of how each stage of the inverter system are organized. Power electronic driver circuit and microcontroller stage is the low voltage side and power electronics inverter circuit is the high voltage side. DC Voltage Input AC Output Power Electronics Inverter Circuit Microcontroller Power Electronic Driver Circuit Figure 3.2: The block diagram of the inverter system Microcontroller Microcontroller is a computer-on-a-chip optimised to control electronic devices. The microcontroller chip used for this project is PIC16F877A. In this project, microcontroller is used to develop the triggering signal for the IGBTs and interfacing to the single phase inverter circuit as a control signal for the gate driver. To implement the microcontroller part, the program for triggering the IGBTs was written in assembly language using the PIC C Compiler. It is written in the text editor or notepad called as source code. It also can be written directly in the PIC C Compiler. Then the file saved is *file.c file. After the program is successfully compiled, the *file.hex file was generated. The hex file was tested by doing the simulation in the Proteus 7 Professional to see the output generated from the program. After got the correct output, the *file.hex file then was uploaded in the PIC16F877A using the PIC programmer. The process of implementing the microcontroller is shown in Figure 3.3. This microcontroller part is the first part that was implemented in hardware. Figure 3.3: The process of implementing the microcontroller Power Electronics Driver A driver is an electronic component used to control another circuit or other component, such as a high-power transistor. Unlike the bipolar transistor, which is current driven, IGBTs, with their insulated gates, are voltage driven. It is allows user to speed up or slow down the switching speeds according to the requirements of the application. The control circuitry supplied low current driving signals that are referenced to controller-ground. A logic one signal was applied to its gate with respect to its source to turn on an IGBT switch, and this signal needs to restrain sufficient power. These requirements can not be met by the control circuit. Figure 3.5 shows a diagram of how signals need to be applied to IGBT switches for effective operation. Figure 3.4: Control signals need to be applied to the gate with respect to the source The driver chose is IR2110 which is a dual driver. The IR2110 High Voltage Bridge Driver is a power integrated circuit that is designed to drive two insulated gate devices. The typical connection of the driver is shown in Figure 3.5. The two channels of the IR2110 are completely independent of one another. The HO output is controlled by the HIN input, and the LO output is controlled by the LIN input. The two inputs of the IR2110 are logically coupled to the shutdown (SD) pin through an AND gate. If HIN and LIN both go high, then the IR2110 will be shut down until one or both inputs go low. This measure helps prevent the catastrophic situation where both Q1 and Q2 turn on at the same time and short circuit the input source. [5] Figure 3.5: Typical connection of IR2110 High Voltage Bridge Driver Isolation using the optocoupler An optocoupler or sometimes refer to as optoisolator allows two circuits to exchange signals yet remain electrically isolated. This is usually accomplished by using light to relay the signal. The standard optocoupler circuits design uses a LED shining on a phototransistor. The signal is applied to the LED, which then shines on the transistor in the ic.   The optocoupler circuit is shown in Figure 3.6 below. In this project, the optocoupler is used as the source and destination are at very different voltage levels, where the source is the microprocessor which is operating from 5V DC but it being used to control the IGBTs which is switching at higher voltage. In such situations the link between the two must be an isolated one, to protect the microprocessor from overvoltage damage. The optocouplers can be used with following advantages for driving high side IGBT in any topology: They can be used to give a very high isolation voltage Signals from DC to several MHz can be handled by opto-couplers. They can be easily interfaced to Microcomputers or other controller ICs or any PWM IC. Figure 3.6: Optocoupler circuit The circuit of low side voltage which consists of PIC, driver and optocoupler was first constructed in the Proteus 7 Professional to see the output generated to be compared with the hardware results. The circuit is as in Figure 3.7 below. Figure 3.7: Low side voltage simulation Power Electronic Inverter The power electronics inverter part is the main part of the system. This is because this circuit will perform the conversion from DC to AC. The circuit consists of four IGBT that act as a switch, DC source and also the load. Figure 3.8 shows a diagram of the H-Bridge power electronics inverter stage. Figure 3.8: H-Bridge power electronics inverter stage. But for this project, the inverter circuit used is the 3-level H-bridge inverter circuit. The circuit was first constructed in the MATLAB as in Figure 3.9 and the simulation of the circuit was done to see the result of simulation. Figure 3.9: 3-level H-bridge inverter circuit constructed in MATLAB The block parameter for the IGBTs was set as in Figure 3.10. The switching frequency used for this circuit is 50Hz. So, the period of waveform can be calculated as below: Switching frequency, f = N / Pf Fundamental period, Pf = 1 / f fundamental = 1/ 50 = 0.02s Figue 3.10: The block parameter setting for the IGBTs In addition, the phase delay or switching times of the IGBTs were also set. Table 3.1 below shows the switching time of the IGBTs. After the simulation was success, the circuit of single 3-level H-bridge inverter was constructed. Table 3.1: The switching time of the IGBTs IGBTs Switching Time IGBT 1 and IGBT 3 10 ms (à Ã¢â€š ¬) IGBT 2 and IGBT 4 0 ms (0 à Ã¢â€š ¬) IGBT 5 and IGBT 7 7 ms (à Ã¢â€š ¬/7) IGBT 6 and IGBT 8 3 ms (à Ã¢â€š ¬/3) For the switch, IRGB10B60KDPBF IGBT was selected for this design. It is very important to choose the correct switches for the inverter circuit because the performance of the design is directly depends on this. This IGBT was chosen because it has ultra fast recovery diode along, it offered benchmark efficiency for motor control and excellent current sharing in parallel operation. In addition the IGBT was selected as they are able withstand the power rating of the inverter. Table 3.2 shows some of the features of the selected IGBT. Table 3.2: The features of IRGB10B60KDPBF IGBT Characteristics Value Drain to Source Voltage (Vds) 600V Drain Current (Id) 12A Rise Time 20ns Fall Time 23ns Short Circuit Capability 10ÃŽÂ ¼s Figure 3.4: 3-level H-bridge inverter circuit

Dc Power Source Utilization Engineering Essay

Dc Power Source Utilization Engineering Essay Many industrial applications have begun to require higher power apparatus in recent years. Some medium voltage motor drives and utility applications require medium voltage and megawatt power level. For a medium voltage grid, it is troublesome to connect only one power semiconductor switch directly. As a result, a multilevel power inverter structure has been introduced as an alternative in high power and medium voltage situations. A multilevel inverter is a power electronic device built to synthesize a desired AC voltage from several levels of DC voltages. The concept of multilevel converters has been introduced since 1975. The term multilevel began with the three-level converter. Subsequently, several multilevel converter topologies have been developed. Plentiful multilevel converter topologies have been proposed during the last two decades. Contemporary research has engaged novel converter topologies and unique modulation schemes. Moreover, there are three different major multilevel converter structures which are cascaded H-bridges converter with separate dc sources, diode clamped (neutral-clamped), and flying capacitors (capacitor clamped) [1] Although the diode clamped multilevel inverter is commonly discussed in the literature, there has been considerable interest in the series connected or cascaded H-bridge inverter topologies [2]. However, the elementary concept of a multilevel converter to achieve higher power is to use a series of power semiconductor switches with several lower voltage dc sources to perform the power conversio n by synthesizing a staircase voltage waveform. Capacitors, batteries, and renewable energy voltage sources can be used as the multiple dc voltage sources [1]. Multilevel power conversion has become increasingly popular in recent years due to advantages of high power quality waveforms, low electromagnetic compatibility (EMC) concerns, low switching losses, and high-voltage capability. The primary disadvantage of multilevel power conversion technology is the large number of semiconductor devices required. This does not yield a significant cost increase since lower-voltage devices may be used. However, an increase in gate drive circuitry and more elaborate mechanical layout are required [3]. Project Overview This project will involve in the design and construction of a single phase 3-level H-bridge inverter using the IGBTs. An H-bridge is an electronic circuit which enables a voltage to be applied across a load in either direction. These circuits allow DC motors to run forwards and backwards. H-bridges are available as integrated circuits, or can be built from discrete components. In this single phase H-bridge inverter circuit, the IGBTs are used as power devices that will be operated as a switch by applying control signal to gate terminal of IGBTs. The insulated gate bipolar transistor or IGBT is a three-terminal power semiconductor device, noted for high efficiency and fast switching. The software that will be used is MATLAB Simulink. Simulink is a commercial tool for modeling, simulating and analyzing multidomain dynamic systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries. The Aims and Objectives The aim of this project is to simulate a single phase 3-level H-bridge inverter (DC to AC converter) using the MATLAB Simulink and constructed it. The objectives of this project are as follows: To investigate the application of H-bridge inverter. To assemble using the software, circuits implementation, and troubleshoot for the hardware. To analyze the operation of the single-phase 3-level inverter for software and hardware. CHAPTER 2 LITERATURE REVIEW Inverter Power electronics converters may be classified into four categories based on the source and types of the desired output characteristics as shown in Figure 1.1 below: OUTPUT AC DC AC INPUTRECTIFIER REGULATORS DC CHOPPERS INVERTERS Figure 2.1: Converter Classification DC-to-AC converter is known as inverter. The function of an inverter is to change a DC input voltage to a symmetrical AC output voltage of desired magnitude and frequency. The variable output voltage could be fixed or variable at a fixed or variable frequency. Inverter can be built in many output phases which is normally use in practice like single phase inverter and three phase inverter. The implementation of the inverter circuit must to be involved in application of the power devices like SCR, MOSFET, IGBT, GTO, and Forced-Commutated Thyristor which is controlled to turning ON and turning-OFF in its operation as a converter. This inverter generally use PWM control signal for producing an AC output voltage [3]. Single Phase H-Bridge Inverter Operation The H-Bridge Inverter or sometimes called Full Bridge consists of four switches (see Figure 2.2). A boost converter is required as this system has no means of stepping up the input. Switches S1-S4, and S2-S3 make up two switch pairs. When S1and S4 are on, the output voltage is a positive pulse, and when S2 and S3 are on, the output is a negative pulse. The phase sequence, frequency, output magnitude and harmonics can be controlled through appropriate switching devices, in conjunction with other equipment. Figure 2.2: Single phase H-bridge inverter Single Phase Multilevel H-Bridges Inverter There are two types of multilevel H-bridge inverter that can be selected in this project which are separated dc source and single DC source. These two types have its pros and cons. The advantages of separated DC source are: The number of possible output voltage levels is more than twice the number of dc sources (m = 2s + 1). The series of H-bridges makes for modularized layout and packaging. This will enable the manufacturing process to be done more quickly and cheaply. while the disadvantage is: Separate dc sources are required for each of the H-bridges. This will limit its application to products that already have multiple SDCSs readily available. Each H-bridge cell requires an isolated dc source. The isolated sources are typically provided from a transformer/rectifier arrangement, but may be supplied from batteries, capacitors or photovoltaic arrays to add up the output voltages. This topology was patented by Robicon Group in 1996 and is one of the companies standard drive products.[2] On the other hand, for the single DC source multilevel H-bridge inverter, the advantage of this type of connection is only one DC supply is used. This will not limit its application to products. And the disadvantage of single DC source is transformer is needed to add up the output voltages Separated DC Source Multilevel H-Bridges Inverter A single-phase structure of an m-level cascaded inverter is illustrated in Figure 2.3. Each separate dc source (SDCS) is connected to a single-phase full-bridge, or H-bridge, inverter. Each inverter level can generate three different voltage outputs, +Vdc, 0, and -Vdc by connecting the dc source to the ac output by different combinations of the four switches, S1, S2, S3, and S4. To obtain +Vdc, switches S1 and S4 are turned on, whereas -Vdc can be obtained by turning on switches S2 and S3. By turning on S1 and S2 or S3 and S4, the output voltage is 0. The ac outputs of each of the different full-bridge inverter levels are connected in series such that the synthesized voltage waveform is the sum of the inverter outputs. The number of output phase voltage levels m in a cascade inverter is defined by m = 2s+1, where s is the number of separate dc sources [1]. Figure 2.3: Single-phase structure of a multilevel cascaded H-bridges inverter An example phase voltage waveform for a nine-level cascaded inverter and all H-bridge cell output waveforms are shown in Figure 2.4. In this thesis, all dc voltages are assumed to be equal. According to sinusoidal-liked waveform, each H-bridge output waveform must be quarter-symmetric as illustrated by V1 waveform in Figure 2.2. Obviously, no even harmonic components are available in such a waveform. To minimize THD, all switching angles must be numerically calculated. Figure 2.4: Waveform showing a nine-level output phase voltage and each H-bridge output voltage. One of the advantages of this structure is the number of possible output voltage levels is more than twice the number of dc sources (m = 2s + 1). The other advantage is the series of H-bridges makes for modularized layout and packaging. This will enable the manufacturing process to be done more quickly and cheaply. On the other hand, the main disadvantage of this topology is that separate dc sources are required for each of the H-bridges. This will limit its application to products that already have multiple SDCSs readily available. The sources are typically provided from a transformer/rectifier arrangement, but may be supplied from batteries, capacitors or photovoltaic arrays. Single DC source Multilevel H-Bridges Inverter Referred to Zhong Du1, Leon M. Tolbert, John N. Chiasson, and Burak ÃÆ'-zpineci thesis entitled A Cascade Multilevel Inverter Using a Single DC Source, a method is presented showing that a cascade multilevel inverter can be implemented using only a single DC power source and capacitors. Without requiring transformers, the scheme proposed allows the use of a single DC power source for examples a battery or a fuel cell stack while the remaining nà ¢Ã‹â€ Ã¢â‚¬â„¢1 DC sources being capacitors. Figure 2.5 shows the Single DC source Multilevel H-Bridges Inverter. The DC source for the first H-bridge (H1) is a DC power source with an output voltage of Vdc, while the DC source for the second H-bridge (H2) is a capacitor voltage to be held at Vdc/2. The output voltage of the first H-bridge is denoted by v1 and the output of the second H-bridge is denoted by v2 so that the output of this two DC source cascade multilevel inverter is v(t) = v1(t)+v2(t). By opening and closing the switches of H1 appropriately, the output voltage v1 can be made equal to à ¢Ã‹â€ Ã¢â‚¬â„¢Vdc, 0, or Vdc while the output voltage of H2 can be made equal to à ¢Ã‹â€ Ã¢â‚¬â„¢Vdc/2, 0, or Vdc/2 by opening and closing its switches appropriately. Figure 2.5: Single DC source Multilevel H-Bridges Inverter IGBTs Versus MOSFETs The power MOSFET is a device that is voltage- and not current-controlled. MOSFETs have a positive temperature coefficient, stopping thermal runaway. The on-state-resistance has no theoretical limit, hence on-state losses can be far lower. The MOSFET also has a body-drain diode, which is particularly useful in dealing with limited free wheeling currents. All these advantages and the comparative elimination of the current tail soon meant that the MOSFET became the device of choice for power switch designs. Then in the 1980s the IGBT came along. The IGBT combines the cross between the power MOSFET and a bipolar power transistor (see Figure 2.2). The IGBT has the output switching and conduction characteristics of a bipolar transistor but is voltage-controlled like a MOSFET. In general, this means it has the advantages of high-current handling capability of a bipolar with the ease of control of a MOSFET. However, the IGBT still has the disadvantages of a comparatively large current tail and no body drain diode. Early versions of the IGBT are also prone to latch up, but nowadays, this is pretty well eliminated. Another potential problem with some IGBT types is the negative temperature co-efficient, which could lead to thermal runaway and makes the paralleling of devices hard to effectively achieve. This problem is now being addressed in the latest generations of IGBTs that are based on non-punch through (NPT) technology. This technology has the same basic IGBT structure (see Figure 2.6) bu t is based on bulk-diffused silicon, rather than the epitaxial material that both IGBTs and MOSFETs have historically used [4]. Figure 2.6: NPT IGBT cross section The comparisons between MOSFETs and IGBTs are as below: Table 2.1: Comparisons between IGBTs and MOSFETs IGBTs MOSFETs Characteristics Low duty cycle Low frequency ( Narrow or small line or load variations High-voltage applications (>1000V) >5kW output power Operation at high junction temperature is allowed (>100 °C) Long duty cycles High frequency applications (>200kHz) Wide line or load variations Low-voltage applications ( Applications Motor control: Frequency Uninterruptible power supply (UPS): Constant load, typically low frequency Welding: High average current, low frequency ( Low-power lighting: Low frequency ( Switch mode power supplies (SMPS): Hard switching above 200kHz Switch mode power supplies (SMPS): ZVS below 1000 watts Battery charging [4] Applications of Inverters There are many application of inverter available today. Some of the applications are as follows: DC power source utilization An inverter converts the DC electricity from sources such as batteries, solar panels, or fuel cells to AC electricity. The electricity can be at any required voltage; in particular it can operate AC equipment designed for mains operation, or rectified to produce DC at any desired voltage. Grid tie inverters can feed energy back into the distribution network because they produce alternating current with the same wave shape and frequency as supplied by the distribution system. They can also switch off automatically in the event of a blackout. Micro-inverters convert direct current from individual solar panels into alternating current for the electric grid. Electric vehicle drives Adjustable speed motor control inverters are currently used to power the traction motor in some electric locomotives and diesel-electric locomotives as well as some battery electric vehicles and hybrid electric highway vehicles such as the Toyota Prius. Various improvements in inverter technology are being developed specifically for electric vehicle applications. In vehicles with regenerative braking, the inverter also takes power from the motor (now acting as a generator) and stores it in the batteries. Uninterruptible power supplies An uninterruptible power supply (UPS) uses batteries and an inverter to supply AC power when main power is not available. When main power is restored, a rectifier is used to supply DC power to recharge the batteries. Variable-frequency drives A variable-frequency drive controls the operating speed of an AC motor by controlling the frequency and voltage of the power supplied to the motor. An inverter provides the controlled power. In most cases, the variable-frequency drive includes a rectifier so that DC power for the inverter can be provided from main AC power. Since an inverter is the key component, variable-frequency drives are sometimes called inverter drives or just inverters. Induction heating Inverters convert low frequency main AC power to a higher frequency for use in induction heating. To do this, AC power is first rectified to provide DC power. The inverter then changes the DC power to high frequency AC power. CHAPTER 3 METHODOLOGY Introduction This chapter exposes the proposed method of this project to built single phase multilevel H-bridge inverter. This project can be divided into two main parts of study which are software and hardware implementation. For the software part, the software used is PIC24 Compiler that used to do the programming for the microcontroller part and MATLAB to do the simulation of the inverter circuit before implemented it in hardware. In addition, Proteus 7 Professional is also used to simulate the driver circuit before do the hardware. The summary of the project is shown in Figure 3.1. Software Part Prepared (Microcontroller) Hardware Part Prepared Troubleshooting Interfacing Result Figure 3.1: The project summary Design of the H-Bridge Inverter System The H-Bridge inverter system can be divided into three main stages that were constructed. It is consists of: Microcontroller Power electronics driver Power electronics inverter Each part was treated as a separate functional block system. Figure 3.2 below shows the block diagram of how each stage of the inverter system are organized. Power electronic driver circuit and microcontroller stage is the low voltage side and power electronics inverter circuit is the high voltage side. DC Voltage Input AC Output Power Electronics Inverter Circuit Microcontroller Power Electronic Driver Circuit Figure 3.2: The block diagram of the inverter system Microcontroller Microcontroller is a computer-on-a-chip optimised to control electronic devices. The microcontroller chip used for this project is PIC16F877A. In this project, microcontroller is used to develop the triggering signal for the IGBTs and interfacing to the single phase inverter circuit as a control signal for the gate driver. To implement the microcontroller part, the program for triggering the IGBTs was written in assembly language using the PIC C Compiler. It is written in the text editor or notepad called as source code. It also can be written directly in the PIC C Compiler. Then the file saved is *file.c file. After the program is successfully compiled, the *file.hex file was generated. The hex file was tested by doing the simulation in the Proteus 7 Professional to see the output generated from the program. After got the correct output, the *file.hex file then was uploaded in the PIC16F877A using the PIC programmer. The process of implementing the microcontroller is shown in Figure 3.3. This microcontroller part is the first part that was implemented in hardware. Figure 3.3: The process of implementing the microcontroller Power Electronics Driver A driver is an electronic component used to control another circuit or other component, such as a high-power transistor. Unlike the bipolar transistor, which is current driven, IGBTs, with their insulated gates, are voltage driven. It is allows user to speed up or slow down the switching speeds according to the requirements of the application. The control circuitry supplied low current driving signals that are referenced to controller-ground. A logic one signal was applied to its gate with respect to its source to turn on an IGBT switch, and this signal needs to restrain sufficient power. These requirements can not be met by the control circuit. Figure 3.5 shows a diagram of how signals need to be applied to IGBT switches for effective operation. Figure 3.4: Control signals need to be applied to the gate with respect to the source The driver chose is IR2110 which is a dual driver. The IR2110 High Voltage Bridge Driver is a power integrated circuit that is designed to drive two insulated gate devices. The typical connection of the driver is shown in Figure 3.5. The two channels of the IR2110 are completely independent of one another. The HO output is controlled by the HIN input, and the LO output is controlled by the LIN input. The two inputs of the IR2110 are logically coupled to the shutdown (SD) pin through an AND gate. If HIN and LIN both go high, then the IR2110 will be shut down until one or both inputs go low. This measure helps prevent the catastrophic situation where both Q1 and Q2 turn on at the same time and short circuit the input source. [5] Figure 3.5: Typical connection of IR2110 High Voltage Bridge Driver Isolation using the optocoupler An optocoupler or sometimes refer to as optoisolator allows two circuits to exchange signals yet remain electrically isolated. This is usually accomplished by using light to relay the signal. The standard optocoupler circuits design uses a LED shining on a phototransistor. The signal is applied to the LED, which then shines on the transistor in the ic.   The optocoupler circuit is shown in Figure 3.6 below. In this project, the optocoupler is used as the source and destination are at very different voltage levels, where the source is the microprocessor which is operating from 5V DC but it being used to control the IGBTs which is switching at higher voltage. In such situations the link between the two must be an isolated one, to protect the microprocessor from overvoltage damage. The optocouplers can be used with following advantages for driving high side IGBT in any topology: They can be used to give a very high isolation voltage Signals from DC to several MHz can be handled by opto-couplers. They can be easily interfaced to Microcomputers or other controller ICs or any PWM IC. Figure 3.6: Optocoupler circuit The circuit of low side voltage which consists of PIC, driver and optocoupler was first constructed in the Proteus 7 Professional to see the output generated to be compared with the hardware results. The circuit is as in Figure 3.7 below. Figure 3.7: Low side voltage simulation Power Electronic Inverter The power electronics inverter part is the main part of the system. This is because this circuit will perform the conversion from DC to AC. The circuit consists of four IGBT that act as a switch, DC source and also the load. Figure 3.8 shows a diagram of the H-Bridge power electronics inverter stage. Figure 3.8: H-Bridge power electronics inverter stage. But for this project, the inverter circuit used is the 3-level H-bridge inverter circuit. The circuit was first constructed in the MATLAB as in Figure 3.9 and the simulation of the circuit was done to see the result of simulation. Figure 3.9: 3-level H-bridge inverter circuit constructed in MATLAB The block parameter for the IGBTs was set as in Figure 3.10. The switching frequency used for this circuit is 50Hz. So, the period of waveform can be calculated as below: Switching frequency, f = N / Pf Fundamental period, Pf = 1 / f fundamental = 1/ 50 = 0.02s Figue 3.10: The block parameter setting for the IGBTs In addition, the phase delay or switching times of the IGBTs were also set. Table 3.1 below shows the switching time of the IGBTs. After the simulation was success, the circuit of single 3-level H-bridge inverter was constructed. Table 3.1: The switching time of the IGBTs IGBTs Switching Time IGBT 1 and IGBT 3 10 ms (à Ã¢â€š ¬) IGBT 2 and IGBT 4 0 ms (0 à Ã¢â€š ¬) IGBT 5 and IGBT 7 7 ms (à Ã¢â€š ¬/7) IGBT 6 and IGBT 8 3 ms (à Ã¢â€š ¬/3) For the switch, IRGB10B60KDPBF IGBT was selected for this design. It is very important to choose the correct switches for the inverter circuit because the performance of the design is directly depends on this. This IGBT was chosen because it has ultra fast recovery diode along, it offered benchmark efficiency for motor control and excellent current sharing in parallel operation. In addition the IGBT was selected as they are able withstand the power rating of the inverter. Table 3.2 shows some of the features of the selected IGBT. Table 3.2: The features of IRGB10B60KDPBF IGBT Characteristics Value Drain to Source Voltage (Vds) 600V Drain Current (Id) 12A Rise Time 20ns Fall Time 23ns Short Circuit Capability 10ÃŽÂ ¼s Figure 3.4: 3-level H-bridge inverter circuit

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Self-Fulfilling Prophecy Individuals have long been intrigued by the notion that persons’ expectations can become a reality. These are commonly referred to as self-fulfilling prophecies. Early scientific work in this area examined the Pygmalion effect—when superiors' high expectations of their subordinates' performance are fulfilled. Since this inception, many replication studies have examined this effect within various contexts and settings—e.g., schools, government, and military. Studies of the Pygmalion effect have identified that a key mechanism through which leaders' expectations influence their followers is by raising the followers’ self-expectations, confidence, or self-efficacy. As a widely researched and generally accepted model of motivation, self-efficacy has been defined as â€Å"people’s judgments of their capabilities to organize and execute courses of action required to attain designated types of performances". Persons’ level of self-efficacy has been associated with individual choices, goals, level of effort, skill acquisition, emotional reactions, persistence in the face of real or perceived obstacles and pressures, and intrinsic interest. Therefore it has been found to be related to a variety of outcomes such as job search behaviors and re-employment, better negotiation role-play outcomes athletic performance and occupational life path choices. Even more powerful than the Pygmalion effect, the Galatea effect is a compelling factor in employee performanc...

Operation Barbarossa

Operation Barbarossa was perhaps the boldest, most ambitious but at the same time most foolish and ill-timed operation executed by Nazi Germany during World War II. This operation committed Germany to war against the Soviet Union which it invaded on June 22, 1941 and terminated on March of 1942. In the early stages of the campaign, the Germans employed the same bilitzkrieg tactics that served them well in the western campaigns.They were hoping to duplicate that same victory against the Soviets and were lulled into a false sense of confidence when they covered a lot of ground and scored many victories which netted them scores of prisoners of war. When 1942 came along, German high command began to realize later on how wrong they were and thus began a protracted war in what they came to call the â€Å"eastern front. † This operation was intended to be the fulfillment of Hitler's vision of lebensraum (living space) in his work, Mein Kampf.â€Å"If land was desired in Europe, it c ould be obtained by and large only at the expense of Russia, and this meant that the new Reich must again set itself on the march along the road of the Teutonic Knights of old, to obtain by the German sword sod for the German plow and daily bread for the nation†¦ †¦ Destiny itself seems to wish to point out the way to us here†¦ This colossal empire in the East is ripe for dissolution, and the end of the Jewish domination in Russia will also be the end of Russia as a state. † (cited in Shirer 124, 1044; Riasanovsky 515; Hitler)Politically, the clashing extremist ideologies of both Germany and the Soviet Union gave the Nazis even more impetus to invade Russia, considering it as a new crusade against communism which they believed was the creation of the Jews for whom Hitler and the Nazis could see no good. Furthermore, Hitler envisioned the Slavic people as a race that would serve the purpose of the Aryan race by wither being their slaves or â€Å"sport† whe rein they would provide them with something to hunt or kill to maintain their virility (Hitler).This was an opportunity for the Nazis to eradicate these enemies in one fell swoop, once and for all. The Spanish civil war of 1936 gave the Germans a taste of war against the communist where they even went face to face against Soviet â€Å"volunteers† in this conflict (Riasanovsky 514-515). As Hitler's armies were annexing neighboring states as part of restoring Germany's glory and patrimony, Hitler began conducting diplomatic overtures as part of his strategy to keep potential adversaries at bay, even for just a while and the Soviet Union was one of them.Thus began secret dipomatic maneuvers which resulted in the non-aggression pact between Germany and the Soviet Union prior to the invasion of Poland where the latter was invited to take part in it. Furthermore, this pact served other purposes other than buying time for Germany to attack Russia. Strategically, Germany needed Russi an territory to be able to transport resources to them following the blockade of the sealanes by the Allies, especially oil which was vital to Germany's war economy and machinery (Shirer 821-822).Despite entering into these agreements, secret or otherwise, both Germany and the Soviet Union still harbored suspicions and animosities against each other, primarily due to irreconcilable differences in ideology where both sides represent the opposite of political extremes, fascism and communism. The Soviets too saw the pact as an alliance of convenience on their part as they began their own expansion by invading the Baltic states of Lithuania, Latvia and Estonia as well as Finland, which was an ally of Germany in 1940.For the sake of keeping the peace with the Soviets, the Germans remained silent as their minor ally was attacked by the Soviets. Germany also felt insecure when the Soviets occupied the Baltic states which they also felt was theirs owing to historical precedence and even mor e concerned when the Soviets were also moving into Romania, another German ally further heightening tensions between these two supposed allies but it was rather apparent that conflict between them would be inevitable as both sides were taking advantage of each other, with the Soviets being the first (Riasanovsky 517; Shirer 832-836, 883).The Nazis entered into a treaty with the Soviets as an alliance of convenience hoping to get more from the treaty. As the war was progressing in the west, the Germans were beginning to realize how difficult the Russians were as negotiators as the latter were driving very hard bargains, especially Stalin. It is revealed in captured German government documents that Stalin also took part in negotiations and was a very tough negotiator who could not be pushed into a compromise and always sought a better deal for Russia and was very demanding.No amount of persuasion and even threats could deter the Russian autocrat (Shirer 882). The German war plan calle d for a one-front war in order to conserve and husband their resources. Though most of western Europe was not occupied, Great Britain remained defiant and continued to hold out in a protracted aerial battle over their airspace where they were able to inflict heavy casualties on the German Luftwaffe (air force), thereby forestalling any plans for a seaborne invasion by the Germans well into 1941.By 1941, Hitler began to become impatient on how the campaign against the British was going. It also did not help that Germany was also suffering an acute shortage of resources and this was what prompted Hitler to jump the proverbial gun and attack Russia, thinking also that the British would not give him a problem as he decided to shelve the invasion of Britain and leave it to his U-Boats to strangle Britain economically.By December of 1940, Hitler already had plans for the invasion from his generals and it was hoped that the attack would commence in the spring of 1941. The plan was codename d â€Å"Barbarossa,† after the Holy Roman emperor who was one of the co-leaders of the Third Crusade; an apt name for the operation since Hitler regarded this planned offensive as a new crusade and it also came at a time when relations between Berlin and Moscow were starting to turn sour as both sides appear to sense that they were double-crossing each other (Shirer 1045, 1049).Another reason for Hitler's desire to attack Russia the soonest was to seal Britain's fate, leaving her with no ally when he said: â€Å"But if Russia is smashed, Britain's last hope will be shattered. Then Germany will be master of Europe and the Balkans†¦ In view of these considerations, Russia must be liquidated†¦ The sooner Russia is smashed, the better. † (cited in Shirer 1047) Furthermore, Hitler also said that â€Å"When Barbarossa commences, the world wil hold its breath and make no comment.† (cited in Shirer 1078) Hitler was apparently lulled into a false sense of confi dence following the victories of German forces in Poland and western Europe and he felt they could do it again in Russia which made him even more confident because he regarded the Russians as inferior despite their large population and their inferiority would make it easy for Germany to defeat and conquer them. He was confident that he would succeed where Napoleon had failed, by conquering Russia quickly and in the shortest span of time possible.The rationale for this was to avoid the harsh Russian winter which was one of the reasons why Napoleon failed and he would not want to make that same mistake Napoleon did. Furthermore, if the Russian campaign would drag on beyond winter, they also had to contend with the following spring where the snow-covered ground would turn muddy, which would play havoc on their powerful war machines which they had never encountered in the western front.He was so driven and obsessed in attacking Russia that he disregarded the advice of his commanders to commence campaigns elsewhere by constantly stating Russia had to be eliminated first and that everything else could wait. The plan called for a six-month time table but constant foot-dragging and waging campaigns in the Balkans and North Africa delayed plans well into June of 1941 (Shirer 1087-1088). Alongside the military planning, Hitler also spelled out his political plans for Russia once the invasion commenced in what became known as the â€Å"Commissar Order.† Hitler saw the war also as a battle of ideologies and he saw the need to eliminate those who propagate it when he stated: â€Å"The commissars are the bearers of ideologies directly opposed to National Socialism. Therefore the commissars will be liquidated. German soldiers guilty of breaking international law will be excused. Russia has not participated in the Hague Convention and therefore has no rights under it. † (cited in Shirer 1089) It can further be inferred here that Hitler was intent on deliberately committing murder by ordering the systematic execution of any political commissar captured by German forces.Most of Hitler's commanders objected to it. These were professional soldiers who knew that murder was not part of a soldier's duty and this would be something they would have to deal with when several of them would be brought to trial in Nuremberg in 1945 (Shirer 1089-1090). In an apparent display of overconfidence, Alfred Rosenberg, one of Hitler's lieutenants, prematurely made a proposal on how to divide Russia into political administrations, each with an given German name.The Baltic region and Belarus would be called Ostland; the Ukraine, along with its adjacent areas; Southern Russia running along the Caucasus mountains would be called Kaukasus; the areas surrounding Moscow, Moskau; and Turkestan for the central regions, each ruled by the modern-day German version of the ancient Roman prefect. Furthermore, plans were already in motion on how to best exploit Russia's resou rces. They intend to use it to feed Germany's industries and its people.They were acutely aware of the adverse consequences it would have on the Russian people in terms of hunger but the Nazis could not care less on what would happen even if millions of Russians would perish under their proposed policies (Shirwe 1091-1092). The forces Hitler arrayed against Russia was made up of 175 army divisions, supported by formidable artillery and armored divisions, both from the Wehrmacht (regular army) and his elite Waffen-SS. These were divided into three army groups, North, Center and South, each given specific objectives to capture.To the north, under the command of Field Marshal Wilhelmvon Leeb, the target was Leningrad. As the city's name implies, it was named after Lenin, the acknowledged father of the Russian Revolution which incidentally began in that city, then named Petrograd (St. Petersburg) and the Soviet Union and therefore, one of the symbolic targets of the German invasion forc es. Historially, Hitler believed Leningrad was once part of the territory conquered by the Teutonic Knights of the Middle Ages and he was simply trying to take back what belonged to Germany by virtue of conquest (Salisbury 37).The center group, under Field Marshal Fedor von Bock, would head for the capital Moscow, reminiscent of Napoleon's actions. The southern forces under Field Marshal Gert von Rundstedt would head for Kiev and Rostov-on-Don in what is now part of the Ukraine which was the Soviet Union's agricultural heartland as well as the road to the oil-rich fields of the Caucasus and Black Sea area (Riasanovsky 518-519). Follow-on forces would come soon to do mop-up operations and to deal with any partisan or guerrilla activity in the occupied areas.All in all, the Nazi regime had already made grandiose plans on what to do with Russia, believing they would finally succeed where Napoleon had failed in addition to the fact that Russia's conquest would be the fulfillment of Hitl er's visions defined in Mein Kampf. On the part of the Soviets, they had the numerical superiority over the Germans with roughly 8 million men to the Germany's 4 million which also included its allies from Italy, Hungary, Finland and Romania.They even had ten times the number of artillery, armored vehicles and aircraft arrayed against the Germans as well. In terms of numbers, the Soviets were by no means weak. If there was one weakness of the Red Army, it was its diversity with men from the various Soviet republics and whose dispositions ranged from cooperative to hostile towards one another even before they faced the Germans.Furthermore, majority of the Soviet forces initially arrayed were made up primarily of conscripts coming mainly from the peasantry, a throwback of the Tsarist era. The commissars were the ones who primarily kept them in line, not just to preserve ideological purity but meting out discipline instead of the officers assigned to the units and even tried to lead th em, replacing the ones persecuted even though they lacked the qualifications. Communications and leadership was also poor.This was partly Stalin's fault during the Great Purge of the 1930's where several competent senior officers of the Red Army were victims of the purges, depriving their units of capable leaders. As a result, these units were routed with millions killed and taken prisoner (Parker 60). Overall command was under Field Marshal Georgi Zhukov who had distinguished himself in the far east in border clashes against the Japanese which gave him a reputation of being a successful commander.Countering the three German offensive groups are three â€Å"Directions† tasked with forming the defense of their assigned territory and launch a counteroffensive. They were the North-Western Direction under Colonel Generals Markian Popov and Fyodor Kuznetsov which covers the Baltic region; the Western Direction under General Dimitry Pavlov which covers the areas west of Moscow and the South-Western Direction under Generals Mikhail Kirponos and Ivan Tyulenev concentrating on the Ukraine (Parker 107; Riasanovsky 518).Despite having more war machines compared to the Germans, they were inferior in quality. The Soviets initially had the T-28 medium tanks which could not stand up to the supeior armor the Germans prepared the Panzer I-III series. Although the Soviets had quality armor like the T-34 and KV-1, they were not abundant in number and were reserved for first-line units, particularly the elite â€Å"Guards† units.For air assets, once more, the quality of Soviet combat aircraft was inferior to ther Germans as they fielded the Poikarpov I-16, Lavochkin-3 and Mig-3 which were mediocre compared to the superior Bf109 fighter planes of the Luftwaffe which made short work of the Red Air Force which were on peacetime status, with aircraft parked closely together in the airfields, making them easy targets for high-altitude bombers and the dreaded Stuka dive b ombers of the Luftwaffe (Batty).On the political front, even Stalin was aware of an imminent conflict with Germany and that the treaties they had would not last much longer as tensions between the two supposed allies were increasing as both sides began to sense the duplicity of the other. Yet, he refused to heed the warnings coming from intelligence agents in the field of an impending German attack and those who merely did their duty were branded as â€Å"provocateurs† and censured, if not arrested.He even ignored warnings from British and American emissaries who were aware of the dangers, thinking it was a ruse to make him show his hand prematurely and not wanting to make the mistake Nicholas II did in 1914. Stalin held absolute power and did not permit any autonomy nor initiative among his subordinates (Salisbury 37). Although German aircraft hadalready been intruding into Soviet airspace, Stalin gave orders not to meet or engage them.His hesitation proved costly as it sent a message to the Germans that the Soviets were complacent, making it the ripe time to attack. The first phase of the war began with air strikes on key military bases and cities to sow terror, panic and confusion as well as cripple and hinder Soviet forces. By the end of the opening phase, the Lufwaffe enjoyed total air superiority over Soviet territory, making them virtually unopposed as they managed to destroy a lot of Soviet aircraft on the ground and shoot down those that managed to take off but were inferior in quality.This was followed up by a simultaneous attack by all three German army groups in their respective fronts and they were able to catch the Soviets off guard, resulting in numerous Soviet casualties and prisoners. They would duplicate the same tactic they did in Poland wherein they would bypass heavier enemy units and encircle them, cutting them off from any support and crush them. They would apply the same tactic as well on major Soviet cities, besieging them and s tarving their people although in the case of Leningrad, Hitler wanted it destroyed (Riasanovsky 518; Salisbury 40).Surprisingly, they were happily welcomed by the civilian population in the Ukraine and the Baltic states who hated Stalin and his communist regime. For them, the Germans were liberators instead of invaders and this had helped the Germans gain a foothold into Soviet territory (Batty). However, by the fourth week of the campaign, the progress bogged down as the German forces were overextended and needed time to allow for support units to catch up. By the time they were able to resume again, winter had set in.Even though it provided mobility due to hardened ground, the conditions were do dismal and German forces were beginning to understand now why Napoleon failed as severe blizzards wrought havoc on the invaders who were unprepared for â€Å"General Winter,† the same foe Napoleon faced and had proven to be a far more formidable foe than any army the Germans had fou ght. At the same time, fresh Soviet troops from the east were deployed and they fought doggedly and with more determination, further slowing down the German advance.What had hoped to be finished in three to six months would run for four more years and would eventually bleed German resources dry. The Soviets may have been brought down initially but they were not out of the running as they managed to recover and become stronger in the latter phase of the campaign. In conclusion, Operation Barbarossa started off well but in the middle, it began to lose steam and thus forcing the Germans to fight a kind of war they did not want, especially against Russia which was a war of attrition.It was considered a failure because the Germans failed to meet their objectives of capturing the key cities and failed to meet their timetable, causing them to be caught up in a winter war they were ill-prepared for. This was attributed to the constant delay of the commencement of the attack. The delay cause d them to be caught up by the winter season and Hitler refused to heed his generals' advice for a pause to allow the winter to pass.Hitler's obsession for going on the offensive caused the German forces to be stretched too thin making the rear areas vulnerable to stay-behind forces and partisan attacks which tied down his forces. The dogged and tenacious resistance put up by the Soviets despite their inferior quality bought time for them to transfer their industries to the remote regions beyond the Urals where they were safe from attacks or capture and enabled the Soviets to reconstitute their forces. Finally, they underestimated the capabilities of the Red Army, especially the Nazi leadership who looked down on the Slavs.Finally, the Germans fought a war they did not want, a 3-front campaign: Western Europe, North Africa and Mediterranean and the Eastern Front which severely divided their forces and resources, not to mention fighting multiple enemies, especially with the entry of t he United States into the war. The Soviets too had their faults which nearly cost them the war, and Stalin was to blame for decimating his officer corps during the 1930 purges. His â€Å"iron will† of not permitting retreat also caused numerous casualties and prisoners as his commissars and loyal commanders blindly followed his orders.His saving grace was the leadership in the front provided by Zhukov who cleverly went around Stalin's orders to husband his forces that enabled them to recover and regain lost ground in the subsequent battles owing to the characteristic resilience of the Russian forces, interspersed with patriotic fervor. The Soviets ay have lost the initial battles but they eventually won the war because of this and eventually took the war to the Germans and visited upon them the same havoc they wrought upon them. Works Cited â€Å"Barbarossa (June-December 1941). † The World at War. Writ. Peter Batty. Thames. 1973.Hitler, Adolf. â€Å"Mein Kampf. † Hitler. Org. 1924. Retrieved 17 May 2010 . Parker, Robert Alexander Clarke. The Second World War: A Short History. Oxford: Oxford University Press, 2001. Riasanovsky, Nicholas V. A History of Russia. New York: Oxford University Press, 1984. Salisbury, Harrison E. â€Å"The 900 Days: The Siege of Leningrad. † True Stories of World War II . Ed. Nancy J. Sparks. Pleasantville, New York: The Reader's Digest Association, Inc. , 1969. 35-63. Shirer, William L. The Rise and Fall of the Third Reich. New York: Simon and Schuster, 1960.

Free Essays on Gothic And Renaissance Architecture

Early Gothic During the Romanesque Period many creations and innovations of architecture were occurring in various places, but it wasn’t until the construction of the Abbey Church of St. Denis that Gothic Architecture truly began to take shape. Here at this church in a region called Ile-di-France in northern France the various architectural innovations were brought together and formed the Gothic style. Abbot Suger was a very innovative and energetic man who is said to be responsible for this advancement in architecture. In 1122 Suger was elected abbot of the French Royal Monastery of St. Denis. At this time St. Denis was not in its true splendor. The church was un-kept, overcrowded, and beginning to decay. The original building was built in 775 as a Carolingian basilica. Revisions had been made in 832 to enlarge the eastern chapel, but little work had been done since then. Sugar had aspirations to rebuild the church, yet had other matters that needed his attention before anything could be done. The Abbey was in financial trouble and faced a lot of criticism for the religious practices of the monks from Bernard of Clairvaux. As Suger worked to strengthen the church’s finances and reputation, he researched and developed images of what he would like his church to become once the church itself was more in order. He studied the designs dictated by God, as was written in the Biblical descriptions of the Temple of Solomon. He read what he thought to be writing of St. Denis that documented the use of light’s mystical and metaphysical properties. He took and great interest in the discussions of colored light. Suger was planning on creating a building that was above all other buildings. He was determined to surpass the church of Hagia Sophia that was seen as the most splendid church in Christendom. In order to do so, Suger questioned travelers from Constantinople about the Hagia Sophia and its structure. Once the other concerns of the... Free Essays on Gothic And Renaissance Architecture Free Essays on Gothic And Renaissance Architecture Early Gothic During the Romanesque Period many creations and innovations of architecture were occurring in various places, but it wasn’t until the construction of the Abbey Church of St. Denis that Gothic Architecture truly began to take shape. Here at this church in a region called Ile-di-France in northern France the various architectural innovations were brought together and formed the Gothic style. Abbot Suger was a very innovative and energetic man who is said to be responsible for this advancement in architecture. In 1122 Suger was elected abbot of the French Royal Monastery of St. Denis. At this time St. Denis was not in its true splendor. The church was un-kept, overcrowded, and beginning to decay. The original building was built in 775 as a Carolingian basilica. Revisions had been made in 832 to enlarge the eastern chapel, but little work had been done since then. Sugar had aspirations to rebuild the church, yet had other matters that needed his attention before anything could be done. The Abbey was in financial trouble and faced a lot of criticism for the religious practices of the monks from Bernard of Clairvaux. As Suger worked to strengthen the church’s finances and reputation, he researched and developed images of what he would like his church to become once the church itself was more in order. He studied the designs dictated by God, as was written in the Biblical descriptions of the Temple of Solomon. He read what he thought to be writing of St. Denis that documented the use of light’s mystical and metaphysical properties. He took and great interest in the discussions of colored light. Suger was planning on creating a building that was above all other buildings. He was determined to surpass the church of Hagia Sophia that was seen as the most splendid church in Christendom. In order to do so, Suger questioned travelers from Constantinople about the Hagia Sophia and its structure. Once the other concerns of the...