Patent ID: 8054030

Claim:
A permanent magnet AC (PMAC) motor system, comprising: a PMAC motor including a rotor; a three-phase inverter coupled to the PMAC motor and configured to provide a voltage to the PMAC motor; and a controller coupled to the three-phase inverter and to the PMAC motor, wherein the controller comprises: control logic configured to perform a sensorless control algorithm for controlling the PMAC motor; start/restart logic configured to determine when to start/restart the sensorless control algorithm; drive logic configured to drive the voltage to substantially zero volts in response to a determined start/restart of the sensorless control algorithm; current detect logic configured to detect current in each phase of the three-phase inverter when the voltage is substantially zero volts; and estimation logic configured to estimate a first position of the rotor, a speed of the PMAC motor, or both based on the detected current.