Method and apparatus for detecting faults in demagnetization for an electric motor

In an electric or hybrid-electric vehicle, a voltage monitor (102) directly to a traction motor (38) and / or generator motor (30) is coupled to detect an induced by permanent magnet voltage in the motor at a predetermined rotational speed and no-load condition. A controller (100) compares the detected, induced by the permanent magnet, with an expected voltage reference voltage representing an expected, induced by the permanent magnet, voltage at full magnetization and the predetermined speed. The comparison includes identifying points of coincidence and use of these points to determine a difference in the detected, induced by the permanent magnet, which is caused by a defective component voltage.