Type of DC motor

In modern electronic products, automatic control systems, electronic equipment, household appliances, electronic toys, etc., DC motors have been widely used. The familiar recorders, record players, video recorders, electronic computers, etc., can not lack DC motors. Therefore, the control of DC motor is a very practical technology. This article will detail the control techniques of various DC motors.

DC motors can be broadly classified into four categories:

The first type is a stepper motor with several phase windings. These stepper motors, plus appropriate sequence pulses, allow the spindle to rotate at a precise angle (typically between 1.8° and 7.5°). As long as a suitable pulse sequence is applied, the motor can be continuously rotated at a predetermined speed or direction.

The stepper motor uses a microprocessor or a dedicated stepper motor to drive the integrated circuit, which is easy to implement. For example, a commonly used stepping motor control circuit for SAAl027 or SAAl024.

Stepper motors are widely used where accurate metering of angular rotation is required. For example, the movement of the robot arm, the character selection of the advanced character wheel, the head control of the computer driver, the word control of the printer, etc., all use the stepper motor.

The second type is a permanent magnet inverter DC motor, which is simple in design but extremely versatile. When the rated DC voltage is applied, the speeds are almost equal. These motors are used in fixed speed machines or equipment such as recorders, video recorders, record players or laser players. It is also used in drives with a wide range of shifting speeds, such as small electric drills, model trains, electronic toys, etc. In these applications, it greatly enhances the function of the motor by means of the action of the electronic control circuit.

The third type is the so-called servo motor, which is the actuator in the automatic device. Its biggest feature is controllable. When there is a control signal, the servo motor rotates, and the speed is proportional to the magnitude of the control voltage. After the control signal voltage is removed, the servo motor stops rotating immediately. Servo motors are used in a wide range of applications and are used in almost all automatic control systems. For example, a tachometer motor whose output is proportional to the speed of the motor; or a gearbox drive potentiometer mechanism whose output is proportional to the position at which the potentiometer moves. When such a motor is mated with an appropriate power control feedback loop, its speed can be It is precisely locked to the external oscillator frequency or locked with an external displacement control knob.

Servo motors are commonly used in turntables for phonographs or CD players. The antenna rotation system, the remote control model aircraft and the ship also use the servo motor.

The last category is a two-phase low voltage AC motor. This type of motor is usually powered by a DC power supply to a low frequency oscillator, which is then driven by a low frequency, low voltage AC. Such motors are occasionally used in turntable drives.

Reprinted from the network