JPS62107689A - Starter for dc motor - Google Patents

Abstract

PURPOSE: To obtain a driving unit for a DC motor having high reliability by PWM-controlling a stepdown chopper having a self-extinguishing type switching element and a flywheel diode in response to the current of the motor to accelerate it.

CONSTITUTION: When an operation command is applied, a signal (a) becomes '1'. At this time, the difference of the voltage between a motor 2 and a power source 1 is larger than the set value, and the outputs (b), (c) of a discriminator 8 become '0', '1'. Accordingly, a PWM controller 12 starts operating, and the motor 2 is limited to be accelerated by an allowable current by the current control. When a speed N increases to increase the voltage of a motor and the voltage difference becomes smaller than the set value of the discriminator 8, the logic values of the signals (b), (c) are inverted to stop the PWM control and to close a switch 4a, thereby completing the starting. Thus, since the motor can be accelerated by the allowable current value, the starting time can be shortened, and a mechanical shock can be eliminated.

COPYRIGHT: (C)1987,JPO&Japio