Patent ID: 7242163

Claim:
A device to regulate current provided to a permanent magnet machine responsive to a plurality of phase current signals to produce torque on a shaft comprising: a processing and drive circuit responsive to a direct voltage command signal (Vds) and a quadrature voltage command signal (Vqs) to produce the plurality of phase current signals for input to the permanent magnet machine: a command circuit responsive to a torque input and configured to produce a direct current command signal (Ids) and a quadrature current command signal (Iqs); a D-axis control circuit responsive to the direct current command signal (Ids) to produce the direct voltage command signal (Vds), the D-axis control circuit comprising a first clamp configured to limit the direct voltage command signal (Vds) to values less than or equal to a preselected level that is less than or equal to a voltage magnitude command signal (Vmag*); a Q-axis control circuit responsive to the quadrature current command signal (Iqs) to produce the quadrature voltage command signal (Vqs), the Q-axis control circuit comprising a second clamp configured to limit said quadrature voltage command signal (Vqs) in accordance with the following in a motoring mode: MIN≦ Vqs≦└√{square root over (Vmag *2 −Vds 2 )} ┘*K.