DC motor drive circuit schematic b

DC motor drive circuit schematic b

If you want to realize the forward and reverse rotation of a DC motor, use 4 switches to switch the direction of the current flowing into the motor, as
shown in Figure a. The four switches and the DC motor form the shape of the letter "H", so it is called the "H-type switch method". Using this circuit, you can
control the motor to rotate in both forward and reverse directions.
    As shown in Figure (b), when S1 and S4 are connected, the current flows from terminal A of the motor to terminal B, and the motor starts to rotate forward. If
you disconnect sl and S4, then connect S2 and S3. As shown in Figure (c). Current flows from terminal B to terminal A, and the motor rotates in the opposite direction.
    This circuit is also capable of braking. When sl and S4 are connected and the motor rotates, disconnect sl, connect s2, and
connect S2 and S4 at both ends of the motor, as shown in Figure (d). The generated current generated by the rotating property of the motor flows through Sj and S4; the motor is braked.
Using power control transistors as switches can achieve high-speed on and off switch control. In pulse width modulation control, changing the switch conduction
time can control the level of voltage, so that the motor speed can be freely controlled.