A transformer sub-circuit for use in an electrically operated vehicle includes a bridge circuit which has at least four MOSFETs and capacitors connected in parallel with the MOSFETs, and an inductor connected to the bridge circuit for use as a primary side of a transformer. A control device or controller for the inverter is configured to cause switching of the MOSFETs in such a way that operation is performed at a frequency that is higher than the resonance frequency.