Project Overview

This project is a high-current DC motor control system designed to provide reliable, efficient, and safe motor operation in power-demanding applications such as robotics, mobile rovers, and automation systems.

The design is based on a discrete MOSFET H-Bridge architecture, allowing the system to handle higher currents compared to typical integrated motor driver ICs, while maintaining flexibility and scalability.

Motivation Behind the Project

Many off-the-shelf motor driver ICs suffer from current limitations, thermal issues, or lack of flexibility when used in high-power applications.

The main motivation for this project was to:

Design a robust motor driver capable of handling high current loads

Improve thermal performance by using external power MOSFETs

Gain hands-on experience in power electronics design, gate driving, and high-current PCB layout

Build a solution suitable for real-world applications, not just simulations

This project was also an opportunity to focus on good engineering practices, such as modular schematic design, protection mechanisms, and clean PCB routing.

System Architecture

The schematic is divided into three main sections for clarity and ease of debugging:

1. Power Section

This section handles:

Input power distribution

Filtering and decoupling to reduce noise

Voltage regulation for the MCU and driver circuits

It ensures stable operation of both control and power stages, even under high-current switching conditions.

2. MCU Section (STM32)

An STM32 microcontroller acts as the brain of the system.

It generates control signals to manage:

Motor direction

Motor speed using PWM

Enable and sleep modes for power management and protection

The MCU interfaces directly with the gate driver using EN, PH, and SLEEP signals, allowing precise and responsive motor control.

3. Driver & MOSFET Section

The power stage is built around the DRV8701 gate driver, which controls external N-channel MOSFETs configured as a full H-Bridge.

Key features include:

Efficient high-side and low-side MOSFET driving

Current sensing using an external RSENSE resistor

VREF-based current limiting (current chopping) to protect the motor and power stage

FAULT output with LED indication for real-time diagnostics and fault detection

This architecture provides excellent performance in high-current scenarios while maintaining safety and reliability.

How the System Works

The MCU generates PWM signals to control motor speed.

Direction is selected using the PH signal.

The DRV8701 amplifies these control signals and drives the MOSFET gates.

The MOSFET H-Bridge applies the appropriate voltage polarity to the motor.

Motor current flows through RSENSE, allowing continuous current monitoring.

If an overcurrent condition occurs, the driver limits or shuts down the output and signals a fault.

PCB Design Considerations

Special attention was given to the PCB layout, including:

Wide copper traces and pours for high-current paths

Short loop areas to reduce EMI

Proper separation between power and control signals

Strategic placement of decoupling capacitors close to the driver and MOSFETs

These considerations ensure stable operation, reduced noise, and improved thermal performance.

Conclusion

This project demonstrates a practical and scalable high-current motor driver design, suitable for real-world applications.

It highlights strong fundamentals in power electronics, embedded systems, and PCB design, making it an excellent example of an engineering-focused hardware project.