Patent ID: 7800928

Claim:
An inverter circuit comprising: an inverter including inverter switches coupled to a resonant circuit for providing an AC load current to a load; an inverter drive circuit coupled to the inverter to provide for commutation of the inverter switches; the inverter drive circuit comprising a zero crossing detector circuit coupled to the resonant circuit to receive an AC current signal, wherein the zero crossing detector circuit is operable to compare the AC current signal with a first reference current value, to compare a rate of change of the AC current signal with a rate of change reference value, and to generate a first indicator signal when the AC current signal is at or near the first reference current value and when the rate of change of the AC current signal is at or near the rate of change reference value; and the inverter drive circuit further comprises a switching circuit coupled to the inverter switches and to the zero crossing detector circuit, the switching circuit being responsive to the first indicator signal to provide for zero current commutation of the inverter switches while the AC current signal is increasing.