Hybrid cycloconverters: An exploration of benefits

Nowadays, power electronic converters based exclusively on IGBTs deliver excellent load side performance up to megawatt powers in the low voltage range (200-690 V) and are steadily gaining performance in the medium voltage range as well. However, the medium and high voltage/high power range remains dominated by converters using naturally commutated thyristors (i.e. cycloconverters, current source inverters), which offer poorer output side performance. A new hybrid arrangement was proposed, targeting at the medium and high-power AC/AC range, comprising of a naturally commutated cycloconverter connected to a PWM Voltage Source Inverter, which has improved output voltage quality and is also capable of accurate control of the circulating current. This paper reviews this concept and investigates all other possible hybrid arrangements in comparison with standard cyclcoconverters in aspects of converter performance, cost and complexity to explore the benefits of this new arrangement.