This book is intended to explain the technical principles involved in the many AC variable speed drive systems available today. It deals with all the DC link inverter and direct AC to AC converter systems that are in commercial use.

David Finney, B.Sc., CEng., FIEE, is division manager and chief engineer, responsible for large variable speed drive systems, at the G.E.C. Industrial Controls plant in Rugby, England. In this position he is responsible for the development, design and manufacture of large drive systems for use in mining, metals, paper, oil, and chemical industries throughout the world.

He has been technically involved in the power semiconductor field since 1958, when thyristors were only just emerging, and during this time he has worked on all types of thyristor converters and inverter drives from a few kilowatts up to 10,000 kW using natural and forced commutation techniques and operating in square wave and pulse modulated modes.

He has published a number of articles and given lectures around the world in his chosen subject.

• Chapter 1: AC motors


• Chapter 2: Power switching devices


• Chapter 3: Power switching circuits for variable speed drives


• Chapter 4: The six-step voltage source inverter for induction motors


• Chapter 5: The pulse width modulated voltage source inverter system for induction motors


• Chapter 6: The six-step current source inverter drive


• Chapter 7: The six-step synchro-convertor system for synchronous motors


• Chapter 8: The current source inverter for the capacitor self-excited induction motor


• Chapter 9: The cycloconvertor


• Chapter 10: The slip energy recovery system for wound rotor induction motors