Asymmetric Thyristors for Switching Frequencies above 20 kHz

For applications containing an antiparallel diode across the thyristor in inverters for inductive heating, UPS-systems, AC motor drives, electric welding systems, X-ray power supplies, a new family of asymmetric thyristors (ASCR) with pellet diameters 15, 21, 30, 38 and 56 mm was developed. The advantages of the ASCR can be summed up as follows: i. Reduction of the turn-off time by a factor of 2 to 3, which means scaling down the size of capacitors and inductors in the commutation circuit by the same factor. ii. Reduction of static on-state conduction losses and turn-on switching losses. This results in a higher current handling capacity or leads to smaller cooling equipment, because the total power dissipation is considerably reduced. iii. Doubling of the repetition frequency. This is achieved by the above mentioned improvements and extends the field of application especially in power switching at high frequencies such as inductive heating and electric welding equipment.