US Patent 7759966 Methods and systems for evaluating permanent magnet motors

A method for evaluating a permanent magnet motor, which includes a rotor with a plurality of magnets mounted thereon, and a stator with a plurality of windings in proximity to the rotor and coupled to an inverter, includes spinning the motor such that a voltage is induced in the windings of the stator and the inverter; measuring the voltage on the inverter; calculating the voltage constant from the motor from the measured voltage; comparing the voltage constant to accepted voltage constants; and identifying the motor as not acceptable if the voltage constant is outside of a range of the accepted voltage constants.