Abstract: A multi-phase voltage from a utility grid is applied to a first side of a plurality of open windings of a stator. A phase of the multi-phase voltage is determined. Stator currents measured from a second side of the plurality of open windings are converted to a non-rotating direct-quadrature (d-q) reference frame. A q-axis of the non-rotating d-q reference frame contains a voltage vector defined from the multi-phase voltage, and a d-axis is normal to the voltage vector. A d-axis component of the converted stator currents is applied as an error signal to a proportional-integral controller to determine an output voltage signal. The output voltage signal is converted from the non-rotating d-q reference frame to a reference frame defined by the phase. The output voltage signal is applied to an inverter to define a second output voltage. The second output voltage is applied to the second side of the plurality of open windings.

Abstract: A multi-phase voltage from a utility grid is applied to a first side of a plurality of open windings of a stator. A phase of the multi-phase voltage is determined. Stator currents measured from a second side of the plurality of open windings are converted to a non-rotating direct-quadrature (d-q) reference frame. A q-axis of the non-rotating d-q reference frame contains a voltage vector defined from the multi-phase voltage, and a d-axis is normal to the voltage vector. A d-axis component of the converted stator currents is applied as an error signal to a proportional-integral controller to determine an output voltage signal. The output voltage signal is converted from the non-rotating d-q reference frame to a reference frame defined by the phase. The output voltage signal is applied to an inverter to define a second output voltage. The second output voltage is applied to the second side of the plurality of open windings.