A power supply system for a high speed DC electric motor includes a high voltage DC buss (17) which supplies DC power to the motor (21) and magnetic bearing actuator(19). A capacitor (22) is connected into the DC buss and in maintained in a charged condition by the buss voltage. A DC/DC converter (18) connected to the DC buss supplies low voltage DC power to the motor controller (23) and the bearing controller (24). In the event of a power failure, a signal is generated which causes the motor controller to reverse the motor magnetic field to thereby turn the motor into a generator and supply power to the DC buss.
