How to control dc motor direction

Embedded C Tutorial

By:Pratik Solanki

(09428849462)

Before Embedded C Lets learn first How to control the MOTOR.
Basics of motor control
Unidirectional control

This can be achieved simply by changing the polarity of the applied voltage or a mechanical two way spring loaded switch which also changes the polarity (See Fig. above).

Bi-Directional Or H-bridge control
With the help of relays or opto couplers with amplifiers (some specially designed ICs) we can change the direction of the DC motor rotation. Circuits below shows the simple concept behind H-bride control of DC motors.

In Fig.1 simple H-bridge Connection is shown using switch. Where all the switches are open and the motor is not receiving any potential difference V or current I and hence it is not rotating.

In Fig.2 switches S2 and S3 are open and S1 and S4 are closed which creates a potential difference across the motor and simultaneously a current flows through the circuit which rotates the motor shaft, let’s say, in the clockwise (CW) direction.

Similarly, in Fig.3 switches S1 and S4 are open and S2 and S3 are closed which rotates the motor in anti-clockwise direction.

Pratik Solanki (09067675187)