CONTROL CIRCUIT AND CONTROL METHOD FOR DC MOTOR

摘要

PURPOSE: A control circuit and control method for DC motor is provided to drive the motor at an ultra low speed by controlling the full-wave rectifying waveform applied to the motor through the use of PWM(pulse width modulation) signal. CONSTITUTION: A control circuit comprises a control unit(10) constituted by a latch including a motor driving state display LED and DC input display LED, and a micro computer for controlling the latch; a memory unit(20) connected to the control unit and which provides a control program and data; a key input unit(30) connected to the control unit and display unit, and which performs key input operation with respect to the calculation mode and continuation mode and outputs driving command to the seven segment LED of the display unit; a display unit(40) for driving one or more seven segment LEDs in accordance with the command output from the key input unit; a motor driving unit(50) for driving the motor in accordance with the PWM signal output from the control unit; a rotation speed detection unit(60) for combining the signal obtained as a result of detection of rotation of motor and square wave signal generated from a square wave generation unit(70), and providing the combined signal to the control unit; the square wave generation unit for extracting square wave of a predetermined frequency from AC power, and providing the square wave to the rotation speed detection unit and control unit; a DC signal input unit(80) for detecting DC signal input from an external source, and providing control signal to the control unit; and a reset unit(90) functioning as a watch-dog timer so as to reset the control unit.