A resonant power supply is provided. The resonant power supply comprises a series resonant converter configured to convert an input DC voltage to an output DC voltage to generate an output DC voltage. The series resonant converter includes a switching stage, a resonant inductor, a resonant capacitor, and an isolation transformer. The resonant power supply further comprises a converter controller configured to obtain an actual trajectory radius signal based on a resonant inductor current, a resonant capacitor voltage, and a voltage in association with the isolation transformer. The converter controller is further configured to generate a trajectory radius command signal based on a DC voltage command signal and a DC voltage feedback signal, and to generate control signals to be applied to the switching stage based on the actual trajectory radius signal and the trajectory radius command signal.