Patent ID: 8179157

Claim:
A method for testing a permanent magnet motor, wherein the permanent magnet motor includes a stator having a plurality of coils that share a common node; a first electrical lead, a second electrical lead, and a third electrical lead, all of which are wired to the plurality of coils and are adapted for connection to a polyphase power source; a rotor having a plurality of permanent magnets providing a plurality of magnetic fields; and a rotatable shaft supporting the rotor within the stator; the method comprising: wiring a first resistor, a second resistor, and a third resistor respectively to the first electrical lead, the second electrical lead, and the third electrical lead, wherein the first resistor, the second resistor and the third resistor share a reference node; energizing the permanent magnet motor via the polyphase power source; sensing a differential electrical signal between the reference node and the common node; detecting an imbalance of the plurality of magnetic fields based on the differential electrical signal; and defining an acceptable range of the differential electric signal, wherein the differential electrical signal being beyond the acceptable range indicates that the plurality of magnetic fields are appreciably imbalanced and that the permanent magnet motor is unacceptable for normal use.