Thyristor-diode control circuits.

This paper deals with the voltage control of three-phase circuits using inverse-parallel thyristor-diode (thyrode) pairs. A simple and direct method is introduced to determine the firing and extinction angles of the thyristors for the assumed load power factors. To verify the method of analysis, waveforms of load current and voltage are compared with oscillograms obtained experimentally. The circuit is used to control the speed of an induction motor and torque-speed characteristics are presented with the firing angle as a parameter, Motor current and voltage waveforms are also recorded. [ABSTRACT FROM AUTHOR]