Patent ID: 8823301

Claim:
A washing machine comprising: an A.C.-D.C. converter, comprising a positive output terminal and a negative output terminal, a permanent magnet synchronous motor comprising a rotor and three stator field coils, a three-phase inverter, electrically coupled to the output terminals of the A.C.-D.C. converter, the inverter comprising (i) three load terminals electrically coupled to the three stator field coils of the motor, and (ii) a plurality of control switches operable to connect the three load terminals of the inverter to the output terminals of the A.C.-D.C. converter, and an electronic motor controller, electrically coupled to the inverter, the motor controller comprising (i) a processor and (ii) a memory device, the memory device having stored therein a plurality of instructions which, when executed by the processor, cause the processor to: determine a first set of three current polarities at the three load terminals, while the rotor is rotating and the three stator field coils are de-energized and connected together, the first set of three current polarities including a polarity for each of the three load terminals, detect a change in the current polarity at one of the three load terminals after determining the first set of three current polarities, determine a second set of three current polarities at the three load terminals after detecting the change in the current polarity, the second set of three current polarities including a polarity for each of the three load terminals of the inverter, and determine a rotor position based on the first set of current polarities and the second set of current polarities.