Design integration of a 200 kW GTO RDCL converter

The authors investigate electrical, mechanical, and thermal limitations of device application and resonant circuit design as higher output power and higher switching frequencies are simultaneously pursued in passive clamp resonant DC link (RDCL) converters. The impact of these limitations on resonant component selection, resonant inductor design, clamp transformer design, and resonant bus power distribution at these higher power levels and frequencies is discussed. Resonant circuit design methodology to select the resonant components is formulated, based primarily on device electrical and thermal constraints. A clamp transformer designed for ultra-low leakage reactance to control the peak resonant bus voltage magnitude and minimize clamp voltage oscillations is discussed. It utilizes a distributed coaxial winding in an integrated magnetic assembly that combines the resonant inductor and clamp transformer functions into one common core. A total mechanical package assembly that integrated the distributed electrical, mechanical, and thermal models was implemented for a 600 VDC 200 kW RDCL prototype operating GTO (gate turn-off thyristor) devices at 20 kHz