1. A power conversion system, comprising: an AC input coupleable to receive AC input power from a power source; a rectifier operative to convert the AC input power to provide a DC output; an inverter operatively coupled with the DC output of the rectifier to provide an AC output; a filter circuit coupled between the AC input and the rectifier, the filter circuit comprising a plurality of filter capacitors; and a controller operative to identify a suspected resonance condition in the filter circuit if a component of at least one filter current flowing in at least one of the filter capacitors in a predetermined frequency band exceeds a predetermined threshold, and to chan e an operating state of the power conversion system or an external device in response to identification of the suspected resonance condition in the filter circuit.