Why CycloConverter circuits are used as heavy duty drives for high power applications?
Cyclo-converter power circuits can be designed to use thyristors (silicon controlled rectifiers). The control logic can be designed to use discrete transistors rather than integrated circuits or microprocessors. Thyristors were available at an earlier date with higher current and voltage ratings than transistors. That made it possible 40 to 50 years ago to design AC motor speed controls for voltages higher than 600 volts and currents higher than 500 amps allowing electronic speed control of motors rated above 500 horsepower (370 kW). As technology advanced, other power electronic drive designed have been used at all power levels. However, cyclo-converters are less complex and perhaps less expensive, so they may still be used to some extent.