Brushed vs Brushless DC Motors: Key Differences Explained

If you have bought an electric bicycle or an electric car, you probably know that there are two types of motors driving the vehicles: brushed motor and brushless motor. Which one is better? Where you should base your selection at?

Here, we’ll show you the difference between a brushed motor and a brushless motor in this post. Hope it’s helpful for you when you purchase the related products.

Differences in working principle

Structure

Brushed motors are mainly composed by stators, rotors and brushes.

Brushless motor is a typical mechatronics product, which consists of a motor main body and a driver.

Commutation

The brushed motor is mechanically commutated, that is, the magnetic pole does not move, and the coil rotates.

The brushless motor adopts electronic commutation, that is, the coil does not move, and the magnetic pole rotates.

Differences in speed regulation

In fact, both motors regulate voltage to control speed.

Electronic commutation adopted by brushless DC motor makes digital control possible. Brushed DC motor is commutated via carbon brush, and can be controlled by traditional analog circuits such as thyristor, which is relatively simple to run.

Brushed motor speed regulation process

We adjust the voltage of motor power supply. The adjusted voltage and current is converted by rectifier and brush, which changes the magnetic field strength generated by the electrode, and thus changing the rotational speed. This process is called variable voltage speed regulation.

Brushless motor speed regulation process

The voltage of motor power supply remains unchanged. Then we change the control signal of the ESC (Electronic Stability Control) and switching speed of the high-power MOS (Metal-Oxide-Semiconductor Field-Effect Transistor) tube. In this way, we can change rotational speed. This process is called variable frequency speed regulation.

Differences in performance

Brushed motors performance

Advantages:

• Large starting torque makes the shifting smooth, so you can hardly feel the vibration;
• Because of the simple structure, it’s easy to produce, control and maintain.

Disadvantages:

• Carbon brushes are wear out easily, resulting frequent replacement and short life cycle;
• Large running current makes the motor magnetic steel easy to demagnetize, which reduces the life cycle of the motor.

Brushless motors performance

Advantages:

• No brush means no spark generated, which greatly reduces the interference of the spark to the remote control radio equipment;
• No brush also means smaller friction, so your motor don’t wear out easily.

Disadvantages

• The speed is controlled by the frequency change. So you’ll feel there is slight vibration when you start or brake;
• The controller of brushless motor is more complicated than that of brushed motor;
• The motor needs to be waterproofed. If the water enters into the hall elements and silicon steel sheets inside the motor, these parts can be easily damaged.

Both motors have their own advantages and disadvantages. If you want a cheap motor and don’t think it troublesome to change the brushes, it’s okay to use a brushed motor. If you want the motor to have a long life and hate to change the brushes, you can choose a brushless motor at a relatively high cost. In short, please choose the right one as per your needs.

Are you interested in knowing more? Feel free to contact us or leave a comment. We’d be glad to hear from you.

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