Applications of a power chopper to the thyristor Scherbius

The paper deals with the applications of a chopper to the thyristor Scherbius which recovers slip power of a wound rotor induction machine. An analysis of the steady-state performance of this system is presented. The chopper improves in several characteristics of a conventional system. In particular, the low power factor, which is a disadvantage of the thyristor Scherbius, is significantly improved. A reasonable operation of the chopper can realise a shorter overlapping interval at the commutation of a thyristor inverter. The recovery current controlled by the chopper has the pulse-width modulated (PWM) waveform. Such a PWM wave-form can reduce the size of line filter for the waveform shaping. Theoretical and experimental results concerning the chopper controlled thyristor Scherbius system are presented.