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Brushless vs. Brushed Motors

When selecting a dc motor for your application, one crucial decision you’ll face is whether to choose a brushed or brushless motor type. This page will guide you through the key factors to consider when deciding between a brushless and brushed motor. From examining their construction and operation to evaluating their performance, we will discuss these two types of motor in detail. At the end, you’ll have a clear understanding of which motor is best suited for your specific application. Let’s look deeper into the brushless vs brushed motor debate to help you make an informed decision.

What are the differences between Brushless motors and Brushed motors?

Brushed Motor

A brushed motor, or brush motor, is a simple device that converts electrical energy into mechanical energy. It consists of several key components: a permanent magnet, a rotor, a stator, brushes, and a commutator.

The working principle is straightforward. When an electric current flows through the rotor’s armature windings, it generates a magnetic field. This field interacts with the permanent magnet on the stator, causing the rotor to rotate. The brushes, typically made of carbon or precious metals, maintain constant physical and electrical contact with the commutator, which is a segmented metal ring that controls the electrical flow to the coil.

The commutator plays a vital role in the motor’s operation. It reverses the direction of the current every time the rotor completes a half turn, ensuring a continuous rotation. The brushes provide a connection between the input power source and the commutator, allowing the current to flow and energize the motor.

The brushed dc motor’s simplicity allows for easy control of speed and torque through varying the current. However, it also leads to certain limitations, primarily the limited lifespan due to brush wear, as well as sparking. These drawbacks have led to the development of more advanced motor technologies, like brushless motors, which offer improved efficiency and durability. However, brushed motors remain widely used in various applications, ranging from power tools to household appliances.

brushed dc motor construction
Construction and Working Principles of Brushed DC Motor

DC Motor & Small Gear Motor Basics

Brushless Motor

A brushless motor, or BLDC motor, is a type of electric motor that consists of a rotor and a stator. Unlike brushed motors, it doesn’t have brushes and commutators. Instead, it uses electronic commutation to control the motor’s operation.

The working principle of a brushless motor is based on the electromagnetic interaction between the rotor and the stator. The stator contains multiple coils, which are strategically energized with electricity. As the current flows through these coils, it creates a magnetic field. The rotor, on the other hand, consists of permanent magnets. When the  magnetic field of the stator windings interacts with the rotor’s magnets, it creates a rotational force.

To control the motor, sensors are used to detect the position of the rotor. This information is then sent to an Electronic Controller, which determines the timing and sequence of the current flowing through the stator coils. By precisely controlling the current, the motor can rotate at desired speeds and in the desired direction.

The absence of brushes and commutators prolongs the motor’s useful life and reduces friction, resulting in a more efficient and durable motor. These types of motors are found in a wide range of applications across various industries like robotics, electric vehicles, and industrial machinery.

brushless motor construction
Construction and Working Principles of Brushless DC Motor

Brushless DC Motor Basics

Advantages of Brushless and Brushed motors

Service Life

Brushed motors, with their physical brushes and commutators, are prone to wear and tear over time. The brushes gradually erode, limiting the motor’s lifespan. On the flip side, brushless motors – devoid of these physical contacts – boast a significantly longer service life. With fewer components susceptible to degradation, they endure extensive use with minimal deterioration.

Size

Size is an important factor when choosing a motor. Brushed motors tend to be bulkier due to the additional components like brushes and a commutator. In contrast, brushless motors exhibit a more compact design. Without the need for brushes, they are smaller and lighter while delivering comparable or even superior power. This size advantage makes brushless motors ideal for applications where space is at a premium.

However, brushless motors require an electronic controller or driver. This can be a small integrated controller attached to the motor, which will make the motor longer, or a much larger external controller that will need to be located somewhere else in the device. You will need to account for the additional electronics into the total size when integrating them into an application.

Audible Noise Generation

Brushed motors can be noisy, primarily due to the physical contact between brushes and the commutator. As the brushes wear down, noise levels may increase. There can also be noise on start-up from sparking. There are typically vent holes on the motors to provide cooling to the motor which can also amplify generated noise.

Brushless motors, operating with minimal friction and devoid of physical contacts, tend to generate less internal noise. However, since they can rotate much faster, they tend to be loud due to air resistance and resonance. They can be quiet in applications like disk drives and medical dispensers where they’re operating in short bursts. They tend to be louder in devices such as drones or electric vehicles where they’re operating at higher speeds for a consistent amount of time. Brushless drivers can also generate something called “Coil Whine”, a sound produced by electrical components when there is high current passing through them.

For quiet operation, we recommend the brushless motor.

Speed Range

Brushed motors often operate at slower speeds in comparison to their brushless counterparts. The physical brushes can cause electrical limitations and increase the risk of sparking at higher speeds.

In contrast, brushless motors excel at a higher speed range. Their electronic commutation allows for precise control over speed. This enables smoother and more efficient operation across various speeds.

Efficiency

Efficiency is a critical differentiator between brushed and brushless motors. Brushed motors tend to be less efficient due to friction and wear on brushes, leading to energy losses.

Brushless motors, operating with electronic commutation, experience minimal friction and exhibit higher efficiency. They convert a larger percentage of electrical energy into mechanical energy, improving overall performance and reducing energy consumption.

Which is better, brushed or brushless motor?

 

Brushless vs Brushed Motors: Choosing the Right One for Your Application

Finding the right motor for your project can be a daunting task if you do not know what aspects to consider. Here are some factors to consider when choosing between a brushed and brushless motor:

DC Motor Selection Tips

Cost

Cost is often a significant consideration when selecting a motor. Brushed DC electric motors are typically more affordable due to their simpler design and manufacturing process.

On the other hand, brushless motors tend to be more expensive. The other cost inflator for BLDC motors is the driver or controllers needed for operation. Depending on device life, you may be able to reach a motor lifespan that results in a cost savings over the long run. If your device is not going to outlast the lifetime of the motor, then a brushed motor is more cost effective.

The electronic controls involved with brushless motor implementation can also lead to more hours spent designing, troubleshooting and problem solving.

Consider your budget, manpower, and the overall cost-effectiveness of the motor based on your specific needs.

Performance vs. Size

If performance is your priority, brushless motors provide more performance advantages. These motors provide a greater output power density, torque, and rotational speed capabilities compared to brushed motors. This makes them ideal for demanding applications. Brushless motors also offer smoother and more precise control, ensuring better overall performance and efficiency.

Brushed motors can be efficient as well, motor technology has improved vastly over the last few decades. Although, at similar torque loads a brushless motor will be slightly smaller in size. This is due mostly to their higher efficiencies.

Brushed motors offer a broader power range, and their simplicity makes them ideal for many applications. Reducing complexity can allow your whole application to perform better. If your design requires a broad torque range, a brushed motor is going to be the better option.

Balance the performance of the motor to the performance of your application when deciding your next steps.

Gearbox Requirements

If you need additional torque, you will need to couple your DC motor with a gearbox. Either a fully integrated gear motor or external gearing will provide additional torque. The trade-off with any gearbox is that they also reduce the output speed and diminish efficiency.

For spur, worm, and planetary gearmotors it is necessary to remember that the input speed from the motor plays a critical part. If the input speed from the motor is too fast it will cause issues with internal gear engagement. Since brushed motors tend to operate at slower speeds, this is less of a concern. When coupling a BLDC motor with a gearbox, this is an important consideration.

Planetary vs. Spur Gear Motors

Control and Precision

Brushless motors provide better control and a high speed range, allowing for precise and variable speed adjustments. Since they need some sort of electronics to operate, they are more precise to start with. For the most optimal precision brushless motor, a Stepper Motor would be the choice.

Brushed motors may generate electromagnetic interference or EMI, which is something to consider. There are ways to limit and filter this noise. Their speed range may be more limited, but additional electronics can be used to control them as well. Magnetic and optical encoders are great for positioning. Utilizing Pulse Width Modulation, or PWM, is an excellent way to control brushed motor speed. Our DC Servo Motors are an excellent solution that utilize a brushed motor paired with an incremental encoder for precise, controlled movement.

Contact Engineering

By weighing these aspects against your project’s specific needs, you can make an informed decision that ensures optimal performance and cost-effectiveness between these two motor technologies.

At ISL Products, we provide top-quality brushed and brushless DC motors that offer market-leading performance. With over four decades of experience in the industry, we manufacture top-quality motors that meet the highest standards.

What sets us apart is our ability to customize our motors to fit your specific needs. Whether you require a unique size, voltage, or performance specifications, our team of experts is dedicated to delivering a solution that exceeds your expectations. We understand that every project is different and are committed to providing personalized solutions that address your specific requirements.

We have built a reputation for delivering products that consistently perform at the highest level, making us the trusted choice for customers worldwide. Contact us today to discuss your project requirements and let us provide you with the perfect motor solution.