Patent ID: 7616466

Claim:
An inverter circuit coupling a DC voltage source having a primary side and a reference side to an AC machine having a plurality of electrical phases, the inverter circuit comprising: for each of the plurality of electrical phases, a first switch coupling the electrical phase to the primary side of the DC voltage source and the second switch coupling the electrical phase with the reference side of the DC voltage source, wherein each of the first and second switches further comprise a switching input; for each of the first and second switches, an associated anti-parallel diode configured to provide an electrical path when the switch associated with the diode is inactive; and a controller coupled to the switching inputs of each of the first and second switches and configured to identify a low operating frequency condition of the AC machine and, in response thereto, to provide a control signal to each switch that comprises a first portion in time and a second portion in time, wherein the first portion applies a first pulse width modulation scheme and the second portion applies a second pulse width modulation scheme different from the first modulation scheme, wherein the first pulse width modulation scheme is a discontinuous pulse width modulation scheme.