Abstract: A synchronous average harmonic current controller is used to simultaneously control line load current and switching transformer current for a resonant power converter. The controller takes its feedback input from a current command and a bridge current sensor which measures total current flowing between the bridge switching nodes. The controller is implemented using an inverting switched capacitor filter. The filter switches two capacitors across the output and inverting node of an error amplifier to integrate and compensate current error synchronously over each half of the fundamental period. The superimposed non-modulated common and modulated difference feedback signals apply duty cycle and phase control which reduces the synchronous average error current. As a result of synchronous average current control of the line load and transformer currents, the primary and secondary bridge have a defined voltage relationship which is straightforward to regulate.

Abstract: A synchronous average harmonic current controller for a bidirectional resonant power converter provides efficient load invariant voltage gain. The controller includes a switched capacitor filter which averages and compensates a current signal over each half of the synchronous switching period. The control signal encodes an independent modulated phase and non-modulated differential duty cycle error response. The error response signals provide negative feedback to a pulse width modulation stage which results in reduction of the synchronous average harmonic current. At this operating point, the harmonic voltage gain is related closely to the commanded bridge duty cycles.