The key to have a good experience with an all-terrain robot is the motor driver used to control the high-torque DC motors. In this article, I look into the best motor drivers for 24V brushed DC motors. This selection is made based on the robot specifications which began to take shape with the article about how to choose the 24V DC motor for an all-terrain robot.
What means the best for my robot? The best high current motor drivers must meet at least two conditions. The first condition is the compatibility with development boards such as Arduino and Raspberry Pi. The second one is more related to future plans. Because I have a limited budget, I have to use the same motor driver for both versions of the robot: remote control and autonomous.
Before listing the high current motor drivers, let’s start with important theoretical things.
The difference between a motor controller and a motor driver
To have a clear view of the difference between a motor controller and motor driver, I’ll make a short overview of both.
Whether you’re using a motor controller or a motor driver, both of them are capable to control the speed and direction of the DC motors. The difference consists of the on-board microcontroller or the lack of it.
A motor controller is a motor driver with a microcontroller on it. The motor driver comes without the microcontroller, so it has to be controlled by another device such as an Arduino or Raspberry Pi to control the speed of the motor and direction. Otherwise, you can use a motor controller designed to take care of generating the PWM and control the motor direction.
Put on paper what you need
If you’re using high-torque DC motors, you absolutely need a high current motor driver. But before buying the motor driver(s) of your project, you have to put on paper the functional requirements of the robot and calculate the output of the DC motors. I already have done this for my project, and you can do it also. Here is the example of how I calculate the theoretical power of the DC motors able to push my robot.
What I need for my project, may differ from what you need for your project. My project should be considered only as an example. As a reference for a heavy-duty robot.
I need one/two/four motor drivers able to feed four high-torque DC motors with the motor voltage per channel of 24V and support a full load current of no more than 19A per motor. If I’ll use only one motor driver with two channels, it should support a maximum current of 38A per channel. For two motor drivers with one channel, each of them should support a maximum current of 38A per channel. If I choose four motor drivers, each of them should support the stall current of the DC motors. In my case, 19A maximum current per motor.
The list
Since I want to use the motor driver for the same robot in autonomous and manually operated mode, I have to avoid some of the most popular motor drivers used by hobbyists to build remote controlled robots. Why? I already had a not very pleasant experience with a Sabertooth motor driver used to control four DC motors of an autonomous robot. Any of the Sabertooth motor drivers does a great job when you manually control a robot. For autonomous robots, I’ll never use again a motor driver designed mainly for remote controlled robots.
With so many online shops and interesting offers, choosing a motor driver seems simple. It’s not. I have spent hours finding a high current motor driver that fits with my robot specifications.
Below, I look into the best motor drivers for 24V brushed DC motors with 10A/20A continuous and support more than 19A/38A stall current per channel.
1. 30A Bi-directional DC Motor Driver
- Price: $$
- Maximum current: 80A peak (1 second), 30A continuously
- Motor voltage: 5V – 30V
- 3.3V and 5V logic level inputs
I need two of these high current motor drivers to feed my high-powered brushed DC motors. It’s compatible with both Arduino and Raspberry Pi, which means that it meets both conditions to be the best motor driver. Also, the board doesn’t require a fan for cooling and incorporates some friendly features for protection and efficiency.
The documentation makes things clear for anyone who uses the motor driver. Here is the manual of the MD30C 30A DC Motor Driver.
2. VNH5019
- Price: $$
- Maximum current: 30A maximum per motor, 12A continuous
- Motor voltage: 5.5V – 30V
- 3.3V and 5V logic level inputs
I need two of these high current DC motor drivers to drive my 24V DC motors. It is a component compatible with Arduino. The Arduino library makes things easier to control the speed and direction of the electric motors. The board is designed to draw heat out of the motor driver chips, but for a better performance I can add heat sinks.
3. Pololu G2
- Price: $$
- Maximum current: ? maximum per motor (probably a higher current than 40A), 21A continuous
- Motor voltage: 6.5V – 40V
- 1.8 V, 3.3 V, and 5 V logic level inputs
I need two of these high-current motor drivers since it can output a continuous current of 21A. The MOSFET H-bridge is designed to drive large brushed DC motors and deliver a continuous 21A without a heat sink.
- Price: $$
- Maximum current: ? maximum per motor (probably a higher current than 30A), 15A continuous
- Motor voltage: 4.8V – 35V
- Directly compatible with Arduino
I need two of these motor drivers to control four brushed 24V DC motors. The board is Arduino compatible and use a BTS7960 H-bridge driver circuit to control the two channels. The driver circuit offers protection over temperature and high voltage.
