Comparative analysis of ZCZVT variable speed drives

This paper presents a comparative analysis between Zero-Current and Zero-Voltage Transition (ZCZVT) IGBT-based inverters applied to variable speed drives. The switching losses of IGBT modules and the losses of auxiliary circuits are measured experimentally. The ZCZVT inverters operate under two distinct concepts: one ZCZVT inverter operation relays on a LC resonant auxiliary circuit, meanwhile the other one makes use of a magnetically-coupled non-resonant auxiliary circuit. To fairly evaluate the inverters, a unified design methodology based on the IGBT dynamic constrains is presented. A modified step-up chopper prototype is used for the realization of the double pulse tests. It ensures the same voltage and current switching conditions for all measurements. The experimental results proved that both ZCZVT inverters quite reduce the main IGBT switching losses, nevertheless, the magnetically-coupled auxiliary circuit is more efficient, chiefly in low load conditions.