A DC motor driver consisting of a single MOSFET with capability of speed and direction control

Generally, a DC motor driver circuit consists of four MOSFETs forming an H-bridge. This type of motor driver can control the speed as well as the direction of rotation of the motor. However, both the functions can be performed using another type of motor driver consisting only one MOSFET and two relays. This paper demonstrates the proposed motor driver circuit having bidirectional speed controllability for motors. The circuit is constructed with a pair of relay (in place of four MOSFETs) that facilitate the direction control and a single MOSFET which enables the speed control of the motor. Moreover, this type of motor driver circuit provides several advantages over the former one. While designing the H-bridge, we have used relays for the High-side instead of the traditionally used MOSFETs and thus, the corresponding intricate MOSFET driving circuitry is also eliminated. As a result, the motor driver circuit is compact and low-priced. Since we do not include the MOSFET driving circuitries such as bootstrapping ICs, transistor circuit, etc., which contribute to the unreliability, the proposed motor driver possess increased reliability. Relays, being mechanical devices, are less prone to the failure due to Electrostatic Discharge (ESD) as compared to the MOSFETs under the same operating conditions. We have illustrated in the paper the designing and testing of this motor driver along with its performance evaluation.