Electric Power / Controls Courseware Sample 85822-F0 A
ELECTRIC POWER / CONTROLS COURSEWARE SAMPLE by the Staff of Lab-Volt Ltd. Copyright 2009 Lab-Volt Ltd. All rights reserved. No part of this publication may be reproduced, in any form or by any means, without the prior written permission of Lab-Volt Ltd. Printed in Canada October 2009
Table of Contents Introduction... V Courseware Outline Asynchronous and Doubly-Fed Generators... VII Sample Exercise Extracted from Asynchronous and Doubly-Fed Generators Exercise 3-9 The Boost Chopper...3 Instructor Guide Sample Exercise Extracted from Asynchronous and Doubly-Fed Generators Exercise 3-11 The Four-Quadrant Chopper...17 Bibliography III
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Introduction The Lab-Volt Asynchronous and Doubly-Fed Generators system, model 8052-1, introduces the principles of electrical power generation and control in the field of wind turbines. Known as the standard for technical training systems in use across virtually every industry and around the globe, Lab-Volt is now using its expertise to facilitate the development, production, installation, and maintenance of the widest variety of Alternative and Renewable Energy Power Training Systems. While most power generation requires the creation, management, and conversion of heat energy into motion with most variations simply involving the way heat is produced alternative and renewable sources are far more varied. Many take advantage of the motion already found in nature; others harness nature s own renewable forms of heat and energy. Capturing and converting that motion or energy often requires very non-traditional methods. Accustomed to breaking down processes and procedures into elemental blocks, Lab-Volt s new training systems take the esoteric and theoretical out of the laboratory and translate it into apparatus that introduce practical, understandable teaching methods. Regardless of the operational scale of the alternative energy sources, Lab-Volt has distilled the essential elements of the process down to safe, hands-on classroom applications, developing each training product and process to yield realistic, repeatable, and logical results. V
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Courseware Outline ASYNCHRONOUS AND DOUBLY-FED GENERATORS Unit 1 Fundamentals for Rotating Machines Introduction to rotating machines. Work, speed, torque, and power. Operation of the Prime Mover / Dynamometer module. Ex. 1-1 Prime Mover Operation Familiarization with the Prime Mover / Dynamometer module operating in the Prime Mover mode. Prime mover speed versus voltage. Friction torque versus speed. Measurement of the opposition torque caused by the machine driven by the Prime Mover. Unit 2 AC Induction Motors The principles of electromagnetic induction. Rotating magnetic field and synchronous speed. Demonstrating the operation and characteristics of AC induction motors. Ex. 2-1 The Three-Phase Squirrel-Cage Induction Motor Creating a rotating magnetic field in a three-phase squirrel-cage induction motor. Synchronous speed. Description and operation of the Three-Phase Squirrel-Cage Induction Motor. Torque versus speed characteristic. Reactive power required for creating the rotating magnetic field. Ex. 2-2 Eddy-Current Brake and Asynchronous Generator Description and operation of the eddy-current brake. Operating a three-phase squirrel-cage induction motor as an asynchronous generator. Demonstrating that an asynchronous generator can supply active power to the AC power network. Demonstrating that asynchronous generator operation requires reactive power. Ex. 2-3 Effect of Voltage on the Characteristics of Induction Motors Saturation in induction motors. Nominal voltage of a squirrel-cage induction motor. Demonstrating the effect of the motor voltage on the torque versus speed characteristic of a squirrel-cage induction motor. Unit 3 Power Electronics Fundamentals Introduction to Reversible DC Power Supply, Rectifiers, Choppers, Inverters, High-Speed Power Switching, and Effect of Frequency in Magnetic Circuits. VII
Courseware Outline ASYNCHRONOUS AND DOUBLY-FED GENERATORS Ex. 3-1 Familiarization with the Reversible DC Power Supply The reversible DC power supply. Implementing a reversible DC power supply using a separately-excited DC motor/generator and a synchronous or asynchronous motor/generator. Operation of a reversible DC power supply implemented with a separatelyexcited DC motor/generator and a three-phase squirrel-cage induction motor/generator (asynchronous motor/generator). Ex. 3-2 Power Diode Single-Phase and Two-Phase Rectifiers Operating principles of the diode. Half-wave rectifier. Rectifier with free-wheeling diode. Battery charger circuit. Single-phase bridge rectifier. Two-phase half-wave rectifier. Ex. 3-3 Power Diode Three-Phase Rectifiers Three-phase, three-pulse rectifier. Three-phase, six-pulse rectifier. Ex. 3-4 Familiarization with the Chopper / Inverter Control Unit (Chopper Modes) Description of the controls, connectors, and indicators of the Chopper / Inverter Control Unit. Operation and use of the Chopper / Inverter Control Unit in a PWM-control chopper and a two-step neutral-zone (bang-bang) control chopper. Examples of various types of choppers built with IGBTs. Ex. 3-5 Familiarization with the Chopper / Inverter Control Unit (Inverter Modes) Operation and use of the Chopper / Inverter Control Unit in various two-phase and three-phase inverters. Introduction to the 120E-, 180E-, and programmed-waveform modulations. Use of synchronous pulse-width modulation (PWM) to obtain a constant V/f ratio three-phase inverter. Examples of inverters built with electronic switches. Ex. 3-6 Familiarization with the IGBT Chopper / Inverter Module Description of the IGBT Chopper / Inverter. Operation of the IGBT Chopper / Inverter module used as a buck chopper. Effect of the duty cycle on the power delivered. Ex. 3-7 Introduction to High-Speed Power Switching Voltage-type circuit. Current-type circuit. Free-wheeling diodes. Use of a capacitor to obtain a voltage-type source. Interconnecting voltage- and current-type circuits. VIII
Courseware Outline ASYNCHRONOUS AND DOUBLY-FED GENERATORS Ex. 3-8 The Buck Chopper Operation of a buck chopper in a simple circuit with a resistive/inductive load. Power flow. Voltage transfer ratio versus the duty cycle. Effect of frequency on the output voltage and current. Power efficiency. Ex. 3-9 The Boost Chopper Operation of a boost chopper in a simple circuit with a resistive load. Power flow. Voltage transfer ratio versus the duty cycle. Effect of frequency on the output voltage and current. Power efficiency. Ex. 3-10 The Buck / Boost Chopper Operation of a buck/boost chopper in a simple circuit with two DC power supplies. Power flow. Voltage transfer ratio versus duty cycle. Ex. 3-11 The Four-Quadrant Chopper Operation of a four-quadrant chopper in a simple circuit with a resistive load. Voltage transfer ratio versus the duty cycle. Power flow. Observing four-quadrant operation on an oscilloscope. Ex. 3-12 The Single-Phase Inverter Using a four-quadrant chopper as a single-phase inverter with variable voltage and frequency (variable voltage and frequency single-phase ac network). A simple dual-polarity DC power supply. Operation of a single-phase inverter built with a dual-polarity DC power supply and two electronic switches, and using either pulse-width modulation (PWM) or 180E-modulation. Ex. 3-13 Saturation and Effect of Frequency in Magnetic Circuits The phenomenon of saturation in magnetic circuits. Saturation curve of magnetic circuits. Effect of frequency in magnetic circuits. Unit 4 Wound-Rotor Induction Machines Familiarization with the operation and characteristics of wound-rotor induction motor and doubly-fed induction generator. IX
Courseware Outline ASYNCHRONOUS AND DOUBLY-FED GENERATORS Ex. 4-1 Wound-Rotor Induction Motor To examine the construction of the Three-Phase Wound-Rotor Induction Motor. To understand exciting current, synchronous speed and slip in a wound-rotor induction motor. To observe the effect of the revolving field and rotor speed upon the voltage induced in the rotor. Ex. 4-2 Wound-Rotor Induction Motor with Short-Circuited Rotor To observe the starting characteristics of the Three-Phase Wound-Rotor Induction Motor having short-circuited rotor windings. You will also show the rotor and stator currents at different motor speeds. Ex. 4-3 Wound-Rotor Induction Motor with Variable Rotor Resistors To observe speed control using external variable resistors connected in series with the rotor windings. Ex. 4-4 Wound-Rotor Frequency Conversion Principles To observe no-load and full-load characteristics of a rotary frequency converter. Ex. 4-5 Speed Control of a Wound-Rotor Generator Using Rotor Resistors To demonstrate how the speed of a wound-rotor generator can be controlled by varying the resistance of the rotor windings. Ex. 4-6 Variable Speed Doubly-Fed Induction Generator Using Rotor Frequency Injection To demonstrate how to synchronize a generator to an AC power network, demonstrate how a doubly-fed induction generator can produce output power at various speeds, how to control the output power level, and how to control the power factor of a generator. Appendices A B C D E F G Circuit Diagram Symbols Impedance Tables Equipment Utilization Chart Reversible DC Power Supply New Terms and Words Configuration Files Saving a Window in WordPad X
Sample Exercise Extracted from Asynchronous and Doubly-Fed Generators
Exercise 3-9 The Boost Chopper EXERCISE OBJECTIVE When you have completed this exercise, you will be familiar with the operation of a boost chopper. DISCUSSION The Boost Chopper As discussed in the previous exercise of this manual, transformers allow AC voltage and current levels to be converted. For example, a step-up transformer is normally used to convert an AC voltage into a higher AC voltage. With DC power, a similar conversion can be performed using a boost chopper. Figure 3-66 shows a boost chopper built with an electronic switch (Q) and a diode (D), and some waveforms related to this circuit. When electronic switch Q switches on, the voltage across its terminals becomes virtually null, the DC power supply voltage (E I ) is applied to the inductor (L), and the current flowing in inductor L (I L ) starts to increase. Simultaneously, diode D switches off since it becomes reverse-biased. At this moment, capacitor C starts to discharge into the load and both the output current (I O ) and voltage (E O ) start to decrease. 3
The Boost Chopper Figure 3-66. Operation of a boost chopper. When electronic switch Q switches off, the voltage across its terminals increases very rapidly until it reaches approximately E O + 0.7 V (due to inductor L). This applies a forward-bias voltage of approximately 0.7 V to diode D, which therefore switches 4
The Boost Chopper on. At this moment, a current equal to I L! I O starts to charge up capacitor C, and both E O and I O start to increase. The DC voltage at the boost chopper output (E O ) is proportional to the DC voltage at the boost chopper input (E I ) and the time the electronic switch is on during each cycle. This time, which is referred to as the on-time (t ON ), is in turn proportional to the duty cycle α of the switching control signal applied to the control signal input of electronic switch Q. The equation relating voltages E O and E I is given by the expression: Thus, voltage E O can be varied by varying the duty cycle α. This equation indicates that voltage E O can range between voltage E I and an infinite voltage when the duty cycle α varies between 0 and 100%. In practice, however, the duty cycle α only approaches 0 and 100%. Therefore, voltage E O can vary between a voltage a little higher than voltage E I and many times voltage E I. In certain circuits, however, the maximum value of the duty cycle α must be limited to limit the maximum voltage the boost chopper can produce. Varying the frequency of the switching control signal while maintaining the duty cycle α constant does not vary the DC voltage and current at the boost chopper output (E O and I O ). However, the ripple on the output voltage decreases as the frequency of the switching control signal increases. The power which the boost chopper delivers at its output (P O ) is equal to the power it receives at its input (P I ) minus the power dissipated in the electronic switch and the inductor. The power dissipated in the electronic switch and the inductor is usually small compared to the power P O. The power efficiency of boost choppers, thus, often exceeds 80%. Notice that the power efficiency is the ratio of the output power on the input power times 100%, as stated in the following equation: Procedure summary In the first part of this exercise, you will set up the equipment required to perform this exercise. In the second part, you will use the circuit shown in Figure 3-67 to observe the operation of a boost chopper. In this circuit, the boost chopper output is connected to a resistive load consisting of resistors R 2 and R 3 connected in series. You will vary the duty cycle of the switching control signal while observing the DC voltage and current at the boost chopper output. This will allow you to verify the relationship between the duty cycle and the DC voltage at the boost chopper input and output, and to determine the direction of power flow. In the third part, you will vary the frequency of the switching control signal while observing the DC voltage and current, as well as the voltage waveform, at the boost chopper output. This will allow you to verify the effect of frequency on these parameters. 5
The Boost Chopper In the fourth part, you will determine the power at the input and output of the boost chopper. You will then compare the output power to the input power and determine the power efficiency of the chopper. EQUIPMENT REQUIRED Refer to the Equipment Utilization Chart, in Appendix C of this manual, to obtain the list of the equipment required to carry out this exercise. PROCEDURE CAUTION! High voltages are present in this laboratory exercise! Do not make or modify any banana jack connections with the power on unless otherwise specified! Setting up the Equipment G 1. Install the Enclosure / Power Supply, Power Supply, Chopper / Inverter, Smoothing Inductors, Resistive Load (2), and Data Acquisition Interface modules in the Mobile Workstation. Install the Chopper / Inverter Control Unit in the Enclosure / Power Supply. Plug the Enclosure / Power Supply line cord into a wall receptacle. Set the power switch of the Enclosure / Power Supply to I (on). G 2. On the Power Supply, make sure that the main power switch is set to O (off) and the voltage control knob to 0%. Make sure that the Power Supply is connected to a three-phase power source. G 3. Make sure that the USB port cable from the computer is connected to the DAI module. Connect the Low Power Inputs of the DAI and Chopper / Inverter modules to the 24-V ac output of the Power Supply. On the Power Supply, set the 24-V ac power switch to I (on). G 4. Open the LVDAM-EMS Oscilloscope window. 6
The Boost Chopper Operation of the Boost Chopper G 5. Set up the circuit shown in Figure 3-67. Figure 3-67. Circuit used to observe the operation of a boost chopper. Make the appropriate connections on the Smoothing Inductors module to obtain an inductance of 0.2 H for L 1. 7
The Boost Chopper Note: Diode D 1 is the power diode connected in parallel with electronic switch Q 1. Diode D 4 (connected in parallel with electronic switch Q 4 ) and electronic switch Q 1 are not shown in the figure because they are not used in this circuit. Electronic switch Q 1 is forced to the off state by connecting SWITCHING CONTROL INPUT 1 to the common point. G 6. Make the following settings: On the Chopper / Inverter Control Unit MODE... CHOP. PWM On the Chopper / Inverter module Switch S 1...lower position In the Oscilloscope window Display E1, E2, AI-1, and I2 on Ch1, Ch2, Ch3, and Ch4. Ch1 Vertical Scale Setting... 100 V/Div. (DC coupling) Ch2 Vertical Scale Setting... 100 V/Div. (DC coupling) Ch3 Vertical Scale Setting... 2 V/Div. (DC coupling) Ch4 Vertical Scale Setting... 0.1 A/Div. (DC coupling) Time Base...1 ms/div. Trigger Source...Ext. Sync. In the LVDAM-EMS application Analog Output AO-1... +10 V Analog Output AO-2... 0 V G 7. Set the Resistive Load modules to obtain a resistance of 400 Ω for R 2 and R 3. G 8. On the Power Supply, set the main power switch to I (on), then set the voltage control knob to 20%. Note: Select convenient vertical scale and position settings in the Oscilloscope window to facilitate observation. Set Analog Output AO-2 so that two complete cycles of the switching control signal coincide as closely as possible with the full width of the Oscilloscope window. This sets the period of the switching control signal to approximately 5 ms. Consequently, the operating frequency of the boost chopper is approximately 200 Hz. Set Analog Output AO-1 so that the duty cycle of the switching control signal is approximately 80% while observing the DC voltage at the boost chopper output in the AVG column of the Waveform Data box in the Oscilloscope window. 8
The Boost Chopper Note: Notice that the duty cycle of PWM control signals 2 and 4 varies linearly from 0.95 to 0.05 as the voltage applied to CONTROL INPUT 1 varies from -10 to +10 V when the Chopper / Inverter Control Unit in the CHOP. PWM mode. G 9. Print or save the waveforms displayed in the Oscilloscope window as OW391. They represent the supply voltage (E I on Ch1), the voltage across the load connected to the boost chopper output (E O on Ch2), the switching control signal applied to electronic switch Q 4 (Ch3), and the load current (I O on Ch4). G 10. Describe how the DC voltage at the boost chopper output varies when the duty cycle of the switching control signal is increased. G 11. Briefly explain why the boost chopper can produce output voltages which are much higher than the voltage applied at its input. G 12. Set Analog Output AO-1 so that the duty cycle of the switching control signal is approximately 5% (minimum value). Print or save the waveforms displayed in the Oscilloscope window as OW392. G 13. Compare the DC voltage at the boost chopper output (Ch2) with the DC voltage provided to the boost chopper (Ch1) (shown in the AVG column of the Waveform Data box). Explain why this circuit is referred to as a boost chopper, knowing that the duty cycle of the switching control signal is set to minimum. 9
The Boost Chopper G 14. Compare the DC voltages at the boost chopper output for both duty cycle values: 5 and 80%. Do your observations confirm that the DC voltage at the boost chopper output increases as the duty cycle of the switching control signal is increased? G Yes G No G 15. Set Analog Output AO-1 so that the duty cycle of the switching control signal increases from 5 to 80% while observing the load current (Ch4). Does the polarity of the load current change as the duty cycle of the switching control signal increases from 5 to 80%? G Yes G No In which direction does the power flow? G 16. Record the supply voltage (E I ) shown in the AVG column (Ch1) of the Waveform Data box. Supply voltage E I = G 17. Calculate the DC voltage which should appear at the output of the boost chopper using the following equation (α = 80%): G 18. Record the output voltage E O shown in the AVG column (Ch2) of the Waveform Data box. Measured output voltage E O = Note: The difference between the calculated and measured value is caused by the voltage drops in the inductor and in the electronic switch. 10
The Boost Chopper Observing the Effect of the Switching Control Signal Frequency G 19. Make the following settings in the Oscilloscope window: Display E1, E2, I1, and I2 on Ch1, Ch2, Ch3, and Ch4. Ch1 Vertical Scale Setting...100 V/Div. (DC coupling) Ch2 Vertical Scale Setting...100 V/Div. (DC coupling) Ch3 Vertical Scale Setting...1 A/Div. (DC coupling) Ch4 Vertical Scale Setting...1 A/Div. (DC coupling) Time Base... 2 ms/div. Trigger Source... Ext. Sync. G 20. Make sure that the duty cycle of the switching control signal is set to 80%. Make sure that the voltage control knob on the Power Supply is set to 20%. Slowly vary the voltage applied to Control Input 2 from -10 to +10 V to vary the frequency of the switching control signal, while observing the average voltage and current at the buck chopper output (shown in the AVG column (Ch2 and Ch4) of the Waveform Data box). Does the frequency of the switching control signal have a significant effect on the average voltage and current the buck chopper provides? If so, describe this effect. G 21. Set the voltage applied to Control Input 2 to obtain a minimum frequency of the switching control signal. Print or save the waveforms displayed in the Oscilloscope window as OW393. G 22. Slowly vary the voltage applied to Control Input 2 from -10 to +10 V to vary the frequency of the switching control signal, while observing the waveform of the current at the boost chopper input in the Oscilloscope window (Ch3). Does the frequency of the switching control signal have a significant effect on the ripple of the current at the boost chopper input? If so, describe this effect. 11
The Boost Chopper Set the voltage applied to Control Input 2 to obtain a maximum frequency of the switching control signal. Print or save the waveforms displayed in the Oscilloscope window as OW394. Output Power Versus Input Power G 23. Set Analog Output AO-2 to +10 V. Make sure that the duty cycle of the switching control signal is still set to 80%. Using the DC voltage and current supplied by the variable-voltage DC power supply to the buck chopper, calculate the power (P I ) which is supplied to the boost chopper. Record the resulting power in the following blank space. Power supplied to the boost chopper P I = G 24. Using the DC voltage and current supplied by the buck chopper to the load, calculate the power (P O ) which is supplied to the load. Record the resulting power in the following blank space. P O = G 25. Calculate the power efficiency of the boost chopper using the following equation: G 26. Is the power at the output of the boost chopper nearly equal to the power at its input? G Yes G No G 27. On the Power Supply, set the voltage control knob to 0%, then set the main power switch and the 24-V ac power switch to O (off). Set the power switch on the Enclosure / Power Supply to O (off). Remove all leads and cables. CONCLUSION In this exercise, you verified that the DC voltage at the boost chopper output increases as the duty cycle of the switching control signal is increased. You found that the minimum DC voltage that can be obtained at the boost chopper output is slightly higher than the DC voltage at its input. 12
The Boost Chopper You saw that power always flows in the same direction in a boost chopper. You observed that the frequency of the switching control signal has no effect on the DC voltage and current provided by the boost chopper. Nevertheless, you saw that as the frequency of the switching control signal increases, the ripple on the input current of the boost chopper decreases. You verified that the power at the boost chopper output is approximately equal to the power at its input. REVIEW QUESTIONS 1. Describe the effect the switching control signal frequency has on the output voltage and current of a boost chopper. 2. A boost chopper is powered by a 12-V dc power supply. What is the output voltage range of this chopper if the duty cycle can vary between 20 and 95%? 3. Briefly describe the operation of the boost chopper. 4. Explain why the maximum value of the duty cycle must be limited in certain boost choppers. 5. Name the component operating with AC power which best compares to the boost chopper. 13
Instructor Guide Sample Exercise Extracted from Asynchronous and Doubly-Fed Generators
Asynchronous and Doubly-Fed Generators EXERCISE 3-11 THE FOUR-QUADRANT CHOPPER ANSWERS TO PROCEDURE STEP QUESTIONS G 8. Electronic switches Q 1 and Q 5 turn on at same time, and they are complementary to electronic switches Q 2 and Q 4. Figure OW3111. Refer to the circuit shown in Figure 3-74. Duty cycle = 70%. Ch1 = AI-1 = switching control signal 1. Ch2 = AI-2 = switching control signal 2. Ch3 = AI-3 = switching control signal 4. Ch4 = AI-4 = switching control signal 5. G 11. Because the voltage switches from positive to negative and stays the same time for each polarity. G 12. DC voltage at the input of the four-quadrant chopper = 117 V. 17
Asynchronous and Doubly-Fed Generators Figure OW3112. Refer to the circuit shown in Figure 3-74. Duty cycle = 50%. Ch1 = AI-1 = switching control signal 1. Ch2 = AI-2 = switching control signal 2. Ch3 = E2 = output voltage of the four-quadrant chopper. Ch4 = I2 = output current of the four-quadrant chopper. Ch5 = E1 = supply voltage of the four-quadrant chopper. G 13. When the duty cycle is minimum for Q 1, E O is approximately equal to -E I. When the duty cycle is maximum for Q 1, E O is approximately equal to +E I. Between the minimum and maximum duty cycles, E O varies. G 14. DUTY CYCLE E O (V) I O (A) 5% -101-1.2 95% 101 1.2 Table 3-11-1. DC voltage and current at the output of the four-quadrant chopper. 18
Asynchronous and Doubly-Fed Generators G 15. The range of the four-quadrant chopper is -E I to +E I. G 16. Yes. G 17. Figure OW3113. Refer to the circuit shown in Figure 3-74. Duty cycle = 80%. Ch1 = AI-1 = switching control signal 1. Ch2 = AI-2 = switching control signal 2. Ch3 = E2 = output voltage of the four-quadrant chopper. Ch4 = I2 = output current of the four-quadrant chopper. G 18. Calculated E O = 71 V. Yes. G 19. No. 19
Asynchronous and Doubly-Fed Generators G 26. Figure G3111. Refer to the circuit shown in Figure 3-75. Ch1 = AI-1 = output current of the four-quadrant chopper. Ch2 = AI-2 = output voltage of the four-quadrant chopper. 20
Asynchronous and Doubly-Fed Generators G 30. Figure G3112. Refer to the circuit shown in Figure 3-75. Ch1 = AI-1 = output current of the four-quadrant chopper. Ch2 = AI-2 = output voltage of the four-quadrant chopper. G 31. Because it is a reversible chopper in voltage and in current (it operates in the four quadrants). G 32. In quadrants 2 and 4. ANSWERS TO REVIEW QUESTIONS 1. When electronic switches Q 1 and Q 5 are on, E I is applied to the load and when Q 2 and Q 4 are on, -E I is applied to the load. If the duty cycle is greater than 50% for Q 1, the average output voltage will be positive and if the duty cycle is less than 50%, the average output voltage will be negative. 2. Yes. 3. The four-quadrant operation can provide a positive or a negative DC voltage regardless of the direction in which the current flows. 21
Asynchronous and Doubly-Fed Generators 4. The equation relating voltages E O and E I is E O = E I x (2α Q1-1). So -24 = 200 x (2α Q1-1) = 56%. 5. The output voltage is reversible. 22
Bibliography Jackson, Herbert W. Introduction to Electric Circuits, 5 th edition, New Jersey: Prentice Hall, 1981 ISBN 0-13-481432-0 Wildi, Theodore. Electrical Machines, Drives, and Power Systems, 2 nd edition, New Jersey: Prentice Hall, 1991. ISBN 0-13-251547-4