Active-Clamped Flyback Converter: Dynamic Load and Cross-Regulation Aspects

This paper presents simulation and experimental results of the active-clamped flyback (ACF) dc-dc converter 57 W implemented as the auxiliary power supply of the primary side of an inductive charging system (ICS) 800 V. First, it was found that the transformer variant, optimized for mass production, had better inductance-change characteristics, but caused lower ACF efficiency than the non-optimized one-which was unexpected. Detailed simulation and analysis of dynamic load changes of ACF are presented confirming proper design of the regulator. The results at 850 V were a bit better than the ones at 620 V input voltage. Detailed measurements of cross-regulation of the ACF in both ICS power-transfer and ICS stand-by modes are presented for the first time. Those results were compared with the ones in previous publications demonstrating that, for the same converter specification, differences exist depending on the transformer used, regulated output, and the chosen converter topology. And, for existing design, no further measures than usage of bleeder resistors, Zener diodes and stacked windings, were needed to keep output voltage fluctuations under control.