Ultra high efficiency bidirectional dc-dc converter with multi-frequency pulse width modulation

An ultra high efficiency bidirectional dc-dc converter with multi-frequency pulse width modulation is proposed in this paper. This method selects a proper switching frequency instead of using detection of instantaneous current to achieve zero-voltage switching (ZVS). Since instantaneous current is not required, control loop instability and noise susceptibility issues can be avoided. The proposed approach allows ease of combining ZVS, multiphase interleaving, and coupled inductor techniques to achieve high efficiency over a wide load range. To verify the proposed approach, a 30 kW hardware prototype has been designed, fabricated and tested. Simulation and experimental results verify the effectiveness of the proposed approach in ZVS operation. Using precision meters and sensors, the efficiency was measured in a wide load range. From 10% to 100% load, the efficiency stays above 98% and peaks at 99.2%.