1.5 kW isolated bi-directional DC-DC converter with a flyback snubber

An isolated bi-directional full-bridge DC-DC converter with high conversion ratio, high output power and soft start-up capability for battery charging/discharging is proposed in this paper. The use of a capacitor and a flyback converter can clamp the voltage spike caused by the current difference between the current-fed inductor and leakage inductance of the isolation transformer, and can reduce the current flowing through the active switches at the current-fed side. Operational principle of the proposed converter is first described, and the design equation is then derived. A 1.5 kW prototype with low-side voltage of 48V and high-side voltage of 360V has been implemented, from which experimental results have verified its feasibility.