A motor drive comprising a first power semiconductor switching device having a
pair of main current carrying terminals, the main current carrying terminals being
coupled in series with a motor load; a first current control loop, the current
control loop having a current sensor for the switching device for controlling the
current through the switching device; a current limiting circuit driving the first
current control loop to maintain the current in the switching device at a desired
level, the current limiting circuit having first and second inputs; a speed regulation
circuit having a first input coupled to a speed control input and a second input
coupled to a feedback voltage from the motor representing the actual motor speed,
the speed regulation circuit providing an output to the first input of the current
limiting circuit to drive the motor to the desired motor speed; and a power limitation
circuit for limiting the power consumed by the motor to a predetermined level and
providing an output to the second input of the current limiting circuit, the power
limitation circuit having an input coupled to receive the feedback voltage from
the motor.