Abstract: A controller is provided for use with electric motors which will achieve a two mode motor operation. In this operation, a first mode is utilized having a torque configuration thus more efficiently providing high torque outputs from the motor. However, a second configuration is also used which more efficiently accommodates high speed operations albeit at the expense of some output torque. The system accomplishes this two mode operation in a low cost manner so as to minimize the overall cost of products or devices utilizing this power control system.

Abstract: A closed control system for controlling the operation of a multiple horsepower brushless direct current motor wherein a current feedback signal representative of the effective motor drive current is constructed from the instantaneous currents flowing in the stator windings. Protective circuitry is provided to shutdown the output power stages in the event of component failures to prevent catastrophic failure of other components in the system.