Simple H-Bridge Motor Driver Circuit

In this tutorial, we are going to make a Simple H-Bridge Motor Driver Circuit using MOSFET. H-bridge is a circuit configured to control the speed and direction of a brushed DC motor. The convenience of the H-bridge motor driver circuit is that a low current digital signal controls a high current motor.

Hardware Components

The following components are required to make Motor Driver Circuit

S.No	Component	Value	Qty
1.	Breadboard	–	1
2.	Connecting Wires	–	1
3.	DC Supply	12V	1
4.	Diode	1N5817	4
5.	Transistor (NPN, PNP)	2N2222, 2N2907	2, 2
6.	DC Motor	–	1
7.	Resistor	1k	4

2N2222 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N2222

2N2907 Pinout

For a detailed description of pinout, dimension features, and specifications download the datasheet of 2N2907

Motor Driver Circuit

Working Explanation

In the circuit, we see that the 4 MOSFET surrounding the motor form an “H” shape. The MOSFETS are used as switches and are activated in diagonal pairs. The diodes D1 to D4 provide a safer path for the back EMF from the motor. Thus it protects the corresponding MOSFET from damage.

The Working of this circuit is very easy to understand. When terminal D is grounded and A is connected to +Vcc, transistors Q1 and Q4 will be on and current passes through the motor from left to right. When terminal B is grounded and C is connected to +Vcc, transistors Q3 and Q2 will be on and current passes through the motor from right to right causing the motor to revolve in the opposite direction.

Important Considerations

The following things fall under consideration while creating H-Bridge motor driver circuit:

Electrical Noise

During the working of the H-Bridge motor driver circuit, the motor can make noises and can damage the MOSFETS. So it must be kept in consideration

Shoot through

Shoot-through means that the two MOSFETS are on at the same time. This shorts the power supply and will likely damage the MOSFETS. We must avoid this condition.

Energy Dissipation

Significant energy dissipates by MOSFET whenever the gate is not fully on or fully off. This causes heating problems and reduces efficiency. We can minimize energy dissipation by making a rapid transition between the off and on states.