Load drive apparatus

Abstract

A system consisting of a motor that drives a load, an analog signal generator that outputs an analog signal which increases as the motor is accelerated, a speed commander that determines a motor speed and commands the motor to operate at the determined speed, and an energizing circuit that receives signal representing difference between the output from the speed commander and the output from the analog signal generator and that energizes the motor so as to operate at the speed in accordance with the signal for the difference is provided with a pulse generator that outputs a pulse corresponding to the current motor speed and with a control circuit that controls the signal for the difference in such way that when the motor is operated at a low speed at which the interval of pulses output from the pulse generator becomes long the signals for the difference issued during a pulse interval sequentially increase. With the aforementioned structure of the systen, during extremely low speed motor operation during which the generated pulse interval becomes long the energizing circuit acts in the direction of increasing motor speed in the course of a pulse interval, thereby enabling the system itself to constitute a load drive apparatus having superior operating performance characteristics without any anxiety about abnnormal reduction of motor speed or motor stop in the worst case.