An optimal phase-shifted control for a series resonant converter involves instantaneous monitoring of state variables (resonant capacitor voltage resonant inductor current and output voltage) and implementation of a control law for providing a quasi-squarewave-with-maximum-coasting (QSWMC) mode of operation. The control law uses the instantaneous resonant inductor current, the instantaneous resonant capacitor voltage and the output voltage to determine the optimal time to perform switching events in order to operate on a desired control trajectory. The QSWMC converter operates at a minimized frequency in a super-resonant mode with zero-voltage switching, minimized electrical stresses, and reduced electromagnetic interference due to nearly sinusoidal resonant tank currents.