Abstract
Operation of thyristor choppers at high frequencies reduces device ratings, filter size and response time in the control system. However, most thyristor choppers require a long time for preparation of the commutation i.e. the charging time of a commutating capacitor etc., and the voltage range at high frequencies is small. To reduce the preparation time is one of the most important points of the high frequency thyristor chopper.
This paper describes a new thyristor chopper circuit which has a commutating circuit separated from the load-main-thyristor circuit and requires no preparation time of the load-main-thyristor circuit for the commutation. Moreover, as a result of separating the commutating circuit, the chopper can recover automatically from a commutation failure, and can operate with a very light load. Therefore, it is suitable for the control device.
An experimental circuit of 100V, 10A has a voltage range of 0.1-1 at 3.5kHz and has a commutation loss of 12-27W at the same frequency.
