What Is a Motor Driver? How Electronics Supply Power to Robot Motors.

What Is a Motor Driver?

A motor driver is an electronic circuit or device that delivers controlled electrical power to a motor.

Motor drivers allow low-power control signals from processors or controllers to regulate motors that require substantially more voltage or current.

For example, a robot's microcontroller may calculate a desired wheel speed, but the microcontroller cannot usually provide the electrical power needed to drive the wheel motor directly.

A motor driver supplies that power through appropriate switching electronics.

Key Takeaways

• Motor drivers regulate the electrical power supplied to motors.
• They commonly use semiconductor switches, including MOSFETs, to control current flow.
• Motor drivers may incorporate protection, sensing, and control functions depending on their design.

How Does a Motor Driver Work?

Imagine a mobile robot with two electric wheel motors.

Its main controller determines how quickly each wheel should rotate.

The motor drivers receive commands and switch electrical power from the battery to the motors.

In a brushed DC motor system, an H-bridge circuit can control the direction of current through the motor.

Reversing the current direction changes the motor's rotation direction.

For a three-phase BLDC motor, the driver uses a different switching arrangement to energize the motor's phases.

A motor controller determines the switching strategy, although some driver products include that logic internally.

What Is an H-Bridge?

An H-bridge is a circuit arrangement that allows electrical current to flow through a load in either direction.

It is commonly used to control brushed DC motors.

For example, an H-bridge can drive a wheel forward or backward by changing the direction of current.

Pulse-width modulation can regulate average electrical power delivered to the motor.

The circuit must be designed to manage current, voltage, heat, and switching conditions.

Motor Driver vs. Motor Controller

The distinction is between determining what should happen and delivering the electrical power required.

Motor controller: Calculates or selects motor-control actions.

Motor driver: Implements the electrical switching needed to drive the motor.

In practice, many products combine both functions.

Some integrated motor-driver chips contain control algorithms, current sensing, and power transistors.

This is why the terms sometimes overlap in product descriptions.

Why Does Driver Selection Matter?

A motor driver must be compatible with the motor's electrical requirements.

Important considerations include supply voltage, operating current, peak current, switching behavior, cooling, and protection features.

For example, a driver that cannot safely handle a motor's peak current may overheat or trigger protective shutdowns.

The complete motor-drive system must also account for electrical disturbances and appropriate fault handling.

Frequently Asked Questions

Can a motor driver operate without a microcontroller?

Some integrated drivers include sufficient control functionality to operate with simple inputs or configuration.

Is a motor driver the same as a power supply?

No. A power supply provides electrical energy. A motor driver controls how that energy is delivered to a motor.

The Bottom Line

Motor drivers provide the power-electronics interface between control signals and physical motor movement. Their capabilities and protection features influence robot performance and reliability.