Using Resonance and Soft-Switching to Enhance Efficiency of Underwater Vehicle's Contactless Charge System

The contactless battery charge system of the autonomous underwater vehicle allows to significantly increase the device operating time in automatic mode under water. Using a transformer with a non-magnetic gap in such a system leads to an increased load on the inverter's power switches. The article presents a solution to the problem of unloading switches using resonant circuits in combination with the "soft switching" mode of the inverter. It is proposed to use a serial LC-circuit connected in parallel to the transformer primary winding, and a capacitor on its secondary side. Recommendations are given for selecting parameters of resonant elements that minimize the charge time of the underwater vehicle's batteries. The using of research results allows to significantly reduce heat loss while maintaining the transmitted active power. The losses in the inverter were reduced from 130 W to 12 W for the transformer idle mode, and from 170 W to 25 W for the transformer short-circuit mode.