A digital current controller for zero-current transition bidirectional converter

This paper presents a digital current controller for zero-current transition (ZCT) bidirectional converters. In order to reduce switching losses and noises, a soft-switching technique is adopted. It is suitable for the pulse-width modulation (PWM), because the resonant transition is very short and it is independent of the switching frequency. A field programmable gate array (FPGA) and a 2.5 MHz analog to digital (A/D) converter can control the inductor current within 2 us. From the experimental results, the current is controlled precisely even if the duty factor is more than 50%. Also, the zero-current transition operation of the main switch is confirmed and it is expected that the efficiency of the converter can be improved. The proposed converter is suitable for an energy transformer between batteries and motors, or generators.