Modern Electrical Studies

1. Power Electronics and Rotating Electric Drives.- 1.1. Introduction.- 1.2. Power Electronics.- 1.2.1. The Thyristor.- 1.3. Rotating Electric Drives.- 1.3.1. The Direct Current Drive.- 1.3.2. The Alternating Current Drive.- 1.3.3. Choice of Drive and Control System.- References and Bibliography.- 2. The Thyristor.- 2.1. Introduction.- 2.2. Semiconductors.- 2.2.1. The Diode.- 2.2.2. The Transistor.- (a) Cut-off.- (b) Linear region.- (c) Saturation.- 2.2.3. The Thyristor.- (a) The diode model of the thyristor.- (b) The two transistor model of the thyristor.- 2.3. Thyristor Characteristics.- 2.3.1. The Thyristor Reverse Biased.- 2.3.2. The Thyristor Forward Biased and Blocking.- 2.3.3. The Thyristor Forward Biased and Conducting.- (a) Light turn-on.- (b) Gate turn-on.- (c) Breakover voltage turn-on.- (d) dv/dt turn-on.- 2.4. Thyristor Turn-Off.- 2.4.1. Ways of Turn-off.- (a) Natural commutation.- (b) Reverse bias turn-off.- (c) Gate turn-off.- 2.4.2 Thyristor Turn-off Time.- 2.5. Thyristor Ratings.- 2.5.7. Voltage Ratings.- 2.5.2. Current Rating.- 2.5.5. Power Rating.- (a) Load current forward conduction loss.- (b) Forward leakage power loss.- (c) Reverse leakage power loss and turn-off loss.- (d) Gate power loss.- (e) Turn-on loss.- 2.5.4. Intermittent Ratings.- 2.6. Thyristor Manufacture.- 2.7. Thyristors in Circuitsx.- 2.7.1. Thyristors in Series.- 2.7.2. Thyristors in Parallel.- 2.7.3. Circuits to Turn on Thyrsitors.- (a) Direct current firing signals.- (b) Pulse firing signals.- (c) Alternating curren t firing signals.- 2.7.4. Circuits to Turn-off Thyristors.- (a) Self commutation by resonance.- (b) Auxiliary resonant turn-off.- (c) Parallel capacitance turn-off.- (d) Series capacitance turn-off.- 2.8. Thyristor Protection Circuits.- 2.8.1. Overvoltage.- 2.5.2. Overcurrent.- 2.5.5. Voltage Surges.- 2.9. Relative Merits of Thyristors.- 2.10. The Bidirectional Triode Thyristor (Triac).- 2.11. Summary.- Worked Examples.- References and Bibliography.- Problems.- 3. Induction Motor Control.- 3.1. Introduction.- 3.2. Induction Motor Starting.- 3.2.1. Thyristor Starting.- 3.3. Induction Motor Speed Control.- 3.3.1. Thyristor Systems for Speed Control.- (a) The alternating current switch.- Worked example.- (b) Inverters.- (i) Inverter classification.- (ii) A C1 inverter for a single-phase induction motor.- Analysis of a C1 inverter with resistive load.- (iii) A class 4 inverter for a three-phase induction motor.- (c) Inverter commutation.- (i) The McMurray inverter.- Worked example.- (ii) The McMurray-Bedford inverter.- (iii) Auxiliary commutating supply.- (d) Voltage proportional to frequency.- (i) Variable ratio transformer.- (ii) Variable voltage converter.- (iii) Inverter voltage control.- (e) Harmonic elimination.- (i) Multiple pulse width control.- (ii) Selected harmonic reduction.- (iii) Harmonic neutralization by wave synthesis.- (f) Appraisal of thyristor three-phase.- (g) Inverters in the induction motor rotor circuit.- References.- Problems.- 4. Direct Current Motor Control.- 4.1. Introduction.- 4.2. Starting Direct Current Motors.- 4.2.1. Thyristors and the Resistance Starter.- 4.2.2. Thyristor Starting without Resistance.- 4.3. Speed Control of Direct Current Motors.- 4.3.1. Thyristor Speed Control.- 4.3.2. Thyristor Controlled Rectifier Converters.- (a) Single-phase half-wave converter.- (b) Single-phase full-wave converter.- Worked example.- (c) Three-phase controlled converters.- (d) Armature and field control.- Worked example.- (e) Converter voltage ripple.- 4.3.3. Thyristor Voltage Choppers.- (a) The Morgan chopper.- (b) The Jones chopper.- (c) The oscillation chopper.- (i) Charging analysis.- (ii) Commutation analysis.- 4.4. Position Control by Direct Current Motors.- 4.4.1. Thyristor Position Control.- (a) Design study of a discontinuous servomechanism for position control using thyristors.- (i) Power circuit.- (ii) Control circuit.- Worked example.- 4.4.2. Alternative circuits.- References and Bibliography.- Problems.- 5. Synchronous Motor Control.- 5.1. Introduction.- 5.2. Synchronous Motor Starting.- 5.2.1. An Inverter for Starting.- 5.3. Speed Control.- 5.3.1. A Speed Control Problem.- (a) A thyristor stepping motor.- (b) A cycloconverter for low speeds.- 5.4. Synchronous Motor Excitation.- 5.4.1. Thyristor Automatic Excitation Control.- (a) Brushless excitation protection during starting.- 5.5. A Synchronous or a Direct Current Motor?.- References and Bibliography.- Appendices.- I. Logic Circuitry for Inverter Control.- II. Logic Circuitry for Bidirectional Converter.- III. Logic Circuitry for On-Off Servo.- References.- Additional Problems for Chapters One, Two, Three and Four.