Electric motors are one of the most important inventions of our time. Two of the most common types are brushed and brushless motors. It’s difficult to imagine a world without them. And yet, despite being such an integral part of modern life, many people have only vague knowledge of them.
We often take them for granted, seeing them often as a mysterious “black box” that simply gets the job done. However, understanding the basics of these two motor technologies can be incredibly valuable and help you make a more informed decision the next time you’re looking to buy a new electric-powered tool or appliance.
In this article, we’ll compare brushed versus brushless motors, highlighting the key differences that set them apart. But before we can do a full comparison it’s important to understand the basics and inner workings of each motor type.
What is a Brushless Motor?
To understand brushless motors better, let’s first take a simplified look into the different main components that make brushless motors work.
Parts of a Brushless Motor
A brushless motor has basically three main parts.
- Stator -Think of the stator as the motor’s sturdy, unmoving frame. It’s like the walls of a house that keep everything in place. Inside the stator, there are special wire coils (electromagnets) arranged in a specific pattern. When electricity from the power source passes through a coil, it creates a magnetic field, effectively turning the coil into a magnet.
- Rotor – This is the rotating part of the motor. The rotor contains strong permanent magnets providing a constant magnetic field and produces the motor’s mechanical output, as it interacts with the magnetic fields generated by the electromagnets on the stator to create torque and enable motion.
- Electronic Speed Controller (ESC) – Now, here’s where the magic happens! The electronic speed controller is a super-smart electronic device. It’s like the brain of the motor. It precisely controls the timing and sequence of electrical pulses delivered to the stator’s electromagnets, thereby regulating the motor’s speed, direction, and torque output.
All these parts work together in perfect harmony to make brushless motors the powerful, reliable, and efficient machines that help make our world go round! Let’s take a closer look at the inner workings of a brushless motor.
How Does a Brushless Motor Work?
Let’s keep it simple and use a simple example to explain how a brushless motor works. Imagine you have a toy car equipped with a small brushless motor and a racetrack.
When you place your toy car on the racetrack the ESC of your toy car’s motor receives electrical current from the race track’s power source, allowing the ESC to send electrical pulses to the electromagnets on the stator.
When an electromagnet is turned on, it creates a magnetic field that attracts or repels the permanent magnets on the rotor. This attraction or repulsion is what causes the rotor to start spinning and making your toy car move forward. Should the electromagnet be kept on continuously, the rotor will simply align itself with the magnetic field and stop spinning.
Therefore, to keep the rotor spinning, the ESC needs to turn on the next electromagnet in the sequence at just the right moment. This creates a new magnetic field that attracts or repels the permanent magnets on the rotor, causing it to continue spinning.
The ESC is using special sensors to know the exact position of the rotor at all times. These sensors are like the eyes of the motor, always watching and sending information back to the ESC. This helps the ESC make sure the electromagnets in the stator are turned on and off at just the right moments.
This clever design allows brushless motors to work efficiently and powerfully, making them perfect for all sorts of cool gadgets, tools and machines.
What is a Brushed Motor?
Now that you have a better understanding of brushless motors let’s take a simplified look at the different main components and the inner workings of a brushed motor.
Parts of a Brushed Motor
Brushed and brushless motors have distinct differences in their construction, which lead to their unique operating characteristics. The construction of brushed motors differs from brushless motors in three significant ways.
- Location of the Magnets – While in a brushless motor, the electromagnets are located on the stator and the permanent magnets on the rotor, it’s the other way around in brushed motors. The electromagnets in a brushed motor are located on the rotor and the permanent magnets on the stator.
- Commutator and Brushes – Brushed motors utilize a mechanical commutator and brushes – hence the name “brushed” motor. They are the mechanical equivalent to the electronic speed controller found in brushless motors.
Picture the commutator as a small, cylindrical piece that’s mounted on the shaft of the motor, so it spins along with the rotor. Surrounding the commutator, you’ll find the brushes. The brushes are typically rectangular or square-shaped conductive blocks. They’re held in place by brush holders, which keep them pressed against the commutator surface using springs or other pressure-applying mechanisms.
How Does a Brushed Motor Work?
One of the fundamental differences between brushed and brushless motors lies in how electricity from the power source is delivered to the electromagnets, which ultimately determines how the motor operates and performs.
You know, by now, that this process is controlled by the electronic speed controller in a brushless motor but how does this process work in a brushed motor? In a brushed motor, electricity is supplied to the rotor’s electromagnets through the mechanical commutation system consisting of the commutator and brushes.
The commutator is divided into several segments, with each segment connected to an electromagnet on the rotor. The number of commutator segments can vary depending on the motor design and the number of electromagnets on the rotor.
Surrounding the commutator, you’ll find the brushes. The brushes are typically rectangular or square-shaped conductive blocks. They’re held in place by brush holders, which keep them pressed against the commutator surface.
As the motor spins, the commutator spins with it. The brushes stay in place, but they keep touching different sections of the commutator. Every time a brush touches a new section, it sends electricity from the power source to a different electromagnet. This makes the electromagnets turn on and off in a specific pattern, which causes the motor to keep spinning.
Just like the ESC in a brushless motor, the commutator is the “traffic controller” for the electricity in a brushed motor, making sure it goes to the correct places at the right time to keep the motor running continuously and smoothly.
Brushless Motor vs Brushed Motor
Now that you understand what brushless and brushed motors are and how they work, let’s compare both motor technologies against each other.
What Are The Advantages of a Brushless Motor?
Brushless motors offer several significant advantages over their brushed counterparts, making them an increasingly popular choice in various applications. Let’s explore the numerous benefits that brushless motors bring to the table.
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Higher Efficiency
One of the primary benefits of brushless motors is their higher efficiency because they generate less friction and heat due to the absence of brushes and a commutator. This means that more of the input power is effectively converted into useful mechanical work, resulting in improved overall efficiency. It is one of the key reasons why brushless motors have become increasingly popular in various applications.
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Longer Lifespan
Without brushes and a commutator, brushless motors have fewer wearing mechanical parts. The absence of physical contact between brushes and commutator eliminates the primary source of wear and tear. That’s why brushless motors can operate for extended periods without requiring replacement.
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Less Maintenance
Brushed motors require regular maintenance. Replacing worn brushes and cleaning the commutator at regular times is necessary to ensure that the brushes maintain proper electrical contact with the commutator and prevent the brushes to stick or slide unevenly against the commutator surface.
While brushless motors have significantly lower maintenance requirements due to the absence of brushes and a commutator, they are not entirely maintenance-free. Brushless motors may still require occasional inspections, cleaning, and lubrication of bearings, depending on the application and operating conditions. However, the overall maintenance burden is much lower than that of brushed motors.
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Improved Speed Control
Brushless motors also excel in terms of speed control. The electronic speed controller in brushless motors allows for quick adjustments to the motor’s speed by varying the timing and duration of electrical pulses sent to the stator’s electromagnets. This allows for faster response times and fine-tuned speed regulation. This is particularly beneficial in applications that require accurate and dynamic motion control, such as robotics, drones, and precision machinery.
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Increased Power-to-Size Ratio
Brushless motors can achieve higher power output for a given size and weight compared to brushed motors. The absence of brushes and commutator allows for more efficient use of the motor’s internal space, enabling more compact and lightweight designs. This is beneficial in applications where space is limited, such as in portable devices or where weight reduction is important, like in chainsaws, leaf or snow blowers for example.
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Quieter Operation
Brushless motors operate with less noise. The absence of brushes and commutator eliminates the mechanical noise generated by their contact and movement, resulting in a significantly quieter motor. This reduced noise level is highly desirable in applications where noise minimization is important, such as in home appliances, audio equipment, or medical devices. The quieter operation of brushless motors enhances user comfort and allows for their use in noise-sensitive environments.
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Design Flexibility
Lastly, brushless motors provide greater flexibility in terms of their physical configuration and form factor. The absence of brushes and commutator allows for more creative and space-efficient motor designs. This design flexibility enables engineers to optimize the motor’s shape and size to fit specific application requirements. Whether it’s in compact electronics or specialized machinery, the adaptability of brushless motors opens up new possibilities for integration and customization.
Brushless Motors in Electric Power Tools
You know, by now, that brushless motors offer several significant advantages over their brushed counterparts, making them an attractive choice for a wide range of applications across different industries.
To better understand and appreciate the significance of brushless motors and their impact, let’s explore how electric power tools benefit from the use of brushless motors, along with the reasons why a brushless motor is the preferred choice.
When it comes to electric power tools, users prioritize features such as high power output, long battery life, durability, and lightweight design.
In brushless motors, the absence of physical brushes and commutator eliminates the friction and electrical resistance that are inherent in brushed motors. This reduction minimizes the energy losses that occur during motor operation.
As a result, more of the available energy from the power source (electrical outlet or battery) is converted into mechanical power, leading to higher power and torque output from the motor, enabling power tools to tackle demanding tasks more effectively.
Additionally, the minimized energy losses mean that less energy is wasted as heat, allowing the motor to run cooler and more efficiently. This efficiency translates into longer battery runtimes for battery-operated power tools before needing to recharge.
Not only does it extend the runtime of cordless power tools but it also positively affects the durability of the motor and the tool itself. The cooler operation and absence of wear-prone components, significantly reduce the risk of overheating and mechanical wear, leading to a longer lifespan and reduced maintenance requirements.
Ergonomics and ease of use are also important considerations for power tools. By eliminating the space required for brushes and commutator, brushless motors allow for smaller motor housings and more streamlined tool designs. This reduction in size and weight makes power tools equipped with brushless motors more comfortable to handle and maneuver, especially during prolonged use.
While the above example showcases the benefits of brushless motors, it’s important to note that this is only one of the many areas where brushless technology is making a significant impact.
As technology continues to advance, we can expect to see further improvements in brushless motor design and materials, and more sophisticated electronic speed controller systems. These advancements will likely lead to even more efficient, powerful, and compact brushless motors, expanding their potential applications and driving innovation across various industries in the years to come.
What Are The Disadvantages of a Brushless Motor?
After reading about the numerous advantages of brushless motors, you may be wondering if there are any drawbacks to this technology. While the benefits of brushless motors are indeed impressive, it’s important to recognize that they also have some limitations and disadvantages. No motor technology is perfect, and brushless motors are no exception.
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Higher Initial Cost
One of the primary disadvantages of brushless motors is their higher initial cost. The complex electronic components, such as the electronic speed controller and position sensors, add to the overall cost of the motor. Additionally, the manufacturing process for brushless motors is often more precise and expensive due to the need for high-quality magnets. This higher initial cost can be a barrier to adoption in cost-sensitive applications.
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Electronic Failures
Brushless motors rely heavily on electronic components which are critical to the motor’s performance. If any of these components fail, the motor may not function properly or not at all. This dependence on electronics can be a disadvantage in applications where reliability is paramount, or where the motor is exposed to harsh environments.
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Skilled Maintenance Requirements
While brushless motors require less maintenance compared to brushed motors, the maintenance tasks can be more complex and require specialized skills. Diagnosing and repairing electronic components issues may require expertise in electronics and motor control systems. This can be a disadvantage in applications where on-site maintenance is necessary, and skilled technicians may not be readily available.
Do Brushed Motors Have Any Advantages?
When considering the choice between a brushless motor and a brushed motor, it’s too easy to assume that brushless motors are always the better option due to their numerous advantages. Brushed motors, despite their limitations, have several advantages too that still make them a viable option in certain situations.
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Lower Initial Cost
One of the primary benefits of brushed motors is their lower initial cost. The simpler design and construction of brushed motors, along with their well-established manufacturing processes, contribute to their lower price point. For projects with tight budgets or where the motor will not be subjected to continuous heavy use, brushed motors can be a cost-effective solution.
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Simpler Design
Another advantage of brushed motors is their simplicity in terms of control and implementation. Brushed motors can be easily controlled using basic circuitry and do not require complex electronic speed controllers like brushless motors do. This simplicity can be beneficial in applications where a straightforward, low-cost control system is desired, or where the added complexity of a brushless motor system is not necessary.
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Long History of Use
Brushed motors also have a long history of use and are well-understood by engineers and technicians. This familiarity can be advantageous in terms of troubleshooting, maintenance, and repair. In some cases, the availability of replacement parts and the knowledge base surrounding brushed motors can make them a more practical choice, especially in applications where maintenance and servicing are critical factors.
Brushless Motor or Brushed Motor?
By now, you have gained a deeper understanding of brushed and brushless motors and their inner workings, characteristics, and the key differences that set them apart.
The next time you read through product descriptions or encounter motor specifications in datasheets, you will no longer be mystified by the terms “brushed motor” or “brushless motor”. Instead, you will have a clear understanding of what these terms signify and how they impact the performance, efficiency, and maintenance requirements of the product you are considering.
But, what to choose: a brushless motor or brushed motor?
Brushless motors are often the preferred choice. Yes, they are more expensive but their increased efficiency, longer lifespan, reduced maintenance, and improved performance can result in cost savings over the life of the motor, offsetting the higher upfront expense.
However, brushed motors can still be a good option in certain scenarios. In addition, advancements in brush and commutator materials, as well as improved motor designs, have helped to mitigate some of their limitations. The modern brushed motors of today can offer better performance, longer lifespans, and reduced maintenance requirements compared to their predecessors.
Ultimately, your decision should be based on a careful evaluation of the specific requirements and constraints of the product you’re planning to purchase. Factors such as performance, efficiency, durability, cost, maintenance needs, and the operating environment should all be considered when making your final choice.
