A resonant converter apparatus includes a plurality of resonant converters connected in parallel, and a control module outputting a pulse width modulation (PWM) control signal to the resonant converters. The control module includes a voltage control loop and a circuit control loop. The voltage control loop compares the sensed output voltage with a predetermined reference voltage, and outputs a PWM control signal to one of the resonant converters so the output voltage of the one converter is equal to the predetermined reference voltage. The current control loop uses the sensed output current of the one converter as a reference current, compares the reference current with the sensed output current from each of the other resonant converters, generates a frequency adjusting variable, and calculates the individual PWM control signal for each of the other converters so the output currents of the plurality of converters are the same.