Brushed Motors vs. Brushless Motors: The Complete Guide
15/01/2025
Sam Nie
Hello every one. This is Sam Nie, the CEO of LUPMOTORS. With 10 year's technical and manufacture experience in the field of 3-phase electric motor, I can provide you definitive guides in the knowledge of 3-phase industrial electric motors,which will help you a lot in selecting electric motors for your applications.
Motors are everywhere, quietly powering our daily lives. They run the fans in our homes, drive the tools in our workshops, and even keep industrial machines humming along. Among them, brushed and brushless motors stand out as the workhorses in everything from simple household gadgets to cutting-edge industrial equipment.
But not all motors are created equal. Choosing the right one can mean the difference between peak efficiency and constant frustration. With brushed motors offering simplicity and affordability, and brushless motors leading in efficiency and longevity, the choice often comes down to your specific needs.
So, how do you decide which is right for you? Let’s dive in and answer the ultimate question: Which motor suits your needs better—brushed or brushless?
1. The Definitions and Structures of Brushed Motors & Brushless Motors
1.1 What Are Brushed Motors?
A brushed motor is one of the simplest and oldest types of electric motors. It relies on physical components—primarily a commutator, brushes, and an armature—to operate. Let’s break it down.
Commutator
Carbon Brush
Armature
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Commutator
This is a cylindrical component divided into multiple segments, each connected to the rotor windings. As the motor shaft rotates, the commutator switches the electrical current between the windings, ensuring the rotor’s magnetic field constantly interacts with the stator’s field.
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Carbon Brushes
These brushes are made of carbon or graphite and are spring-loaded to maintain constant contact with the commutator. Their role is to deliver electric current to the rotating commutator without interruption.
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Armature
This is the rotating part of the motor. When current flows through its windings, the electromagnetic interaction between the rotor and the fixed magnets in the stator creates torque, spinning the shaft.
How It All Works
The carbon brushes press against the commutator when the motor operates.
Current flows from the brushes to the commutator, energizing the rotor windings. The commutator ensures that the current reverses direction at just the right time, keeping the rotor’s magnetic field aligned with the stator’s magnets. This continuous push-and-pull effect is what drives the rotation.
While this setup is efficient for many applications, the constant contact between the brushes and the commutator leads to wear, limiting the motor’s lifespan.
1.2 What Are Brushless Motors?
A brushless motor, also known as a BLDC motor, operates without mechanical brushes or a commutator. Instead, it uses electronic control to generate and manage a rotating magnetic field, ensuring efficient and precise operation. Let’s explore its construction and working principles in detail.
Here’s the Construction of a Brushless Motor
Stator
Rotor
Electronic Controller
Hall Effect Sensors
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Stator
The stator is the stationary part of the motor, housing copper windings arranged into multiple phases, typically three-phase. These windings are energized in a sequence to create a rotating magnetic field. The configuration of the windings determines: 1.Number of poles: Affects torque and speed characteristics. 2.Phase arrangement: Ensures smooth rotation and reduced torque ripple.
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Rotor
The rotor is the moving part, equipped with permanent magnets. These magnets align with the rotating magnetic field created by the stator. The number of poles in the rotor magnets defines the motor's torque and speed capabilities.
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Electronic Controller
The controller acts as the brain of the motor, managing the current flow to the stator windings. It replaces the mechanical commutator found in brushed motors and uses algorithms to determine the precise timing for energizing each winding.
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Hall Effect Sensors
Located near the rotor, these sensors detect its exact position. This information is sent to the controller, which uses it to time the switching of current in the stator windings.
How Brushless Motors Create a Rotating Magnetic Field
1. Generating the Magnetic Field
The controller energizes specific windings in the stator to create a magnetic field. For example:
- Current flows through one set of windings, generating a north magnetic pole.
- The opposite winding generates a south magnetic pole.
2. Sequence and Rotation
Based on input from the Hall sensors, the controller switches the current between the windings in a specific sequence. This sequential switching ensures the magnetic field rotates continuously. The rotor’s permanent magnets follow the rotating field, producing torque.
3. Commutation Without Brushes
Unlike brushed motors, where mechanical brushes handle commutation, brushless motors rely on electronic commutation. The controller precisely times the current flow to maintain synchronization between the rotor and the stator’s magnetic field.
The Principle in Action
1. Energizing the First Phase
The controller energizes the first phase of windings based on rotor position data from the Hall sensors.
2. Rotor Alignment
As the rotor aligns with the magnetic field, the sensors detect its new position.
3. Shifting Current to Next Set of Windings
The controller shifts current to the next set of windings, maintaining the rotating field.
4. Continuous Loop
This process repeats in a continuous loop, keeping the rotor spinning.
Why Brushless Motors Are Superior
Photo: This is a brushless motor.
This advanced method of creating and managing a rotating magnetic field ensures:
- High efficiency due to precise energy usage.
- Minimal heat and noise generation.
- Longevity since no physical components wear out during commutation.
Tip: To get more knowledge about the Brushless DC Motor, please read this article.
Tip: To get more knowledge about the Brushed DC Motor, please read this article.
Video Resources
Quiz: Test Your Knowledge of Part 1: "The Definitions and Structures of Brushed Motors & Brushless Motors"
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2. Pros, Cons, and Main Differences
2.1 Main Differences Comparison
3.1.1 Lifetime
(Source: Engineering.com, IEEE Xplore)
The lifetime of a motor is heavily influenced by its design. Brushed motors, due to the mechanical contact between the brushes and the commutator, typically last around 1,000 to 3,000 hours under normal operating conditions. The constant friction causes wear and tear, leading to frequent maintenance and eventual replacement of components. This limits their suitability for high-duty or continuous-use applications.
In contrast, brushless motors have a significantly longer lifespan. Thanks to the absence of brushes and the use of electronic commutation, they can operate for 10,000 to 20,000 hours or more, depending on the quality of the motor and its usage conditions. Some high-quality brushless motors in industrial settings have been known to exceed 50,000 hours with minimal maintenance. This makes them the preferred choice for applications requiring long-term reliability, such as electric vehicles and drones.
3.1.2 Speed and Acceleration
Brushed Motor
Brushed motors have a linear speed response, but their speed and acceleration are limited by the mechanical constraints of the brushes and commutator. As speed increases, friction and heat buildup reduce efficiency.
Brushless Motor
Brushless motors, on the other hand, shine in high-speed applications. The precise electronic switching of current allows for rapid acceleration and consistent speed control without the mechanical limitations present in brushed motors.
3.1.3 Electrical Noise
Brushed Motor
Brushed motors generate significant electrical noise. The contact between brushes and the commutator produces small electrical arcs, creating interference that can disrupt sensitive electronics nearby.
Brushless Motor
Brushless motors avoid this issue entirely. The absence of brushes and electronic switching ensures minimal electrical noise, making them suitable for devices requiring clean and stable electrical environments.
3.1.4 Acoustic Noise
Brushed Motor
The physical friction in brushed motors also leads to higher acoustic noise. The constant brushing of carbon against the commutator creates a noticeable hum or grinding sound, which becomes more pronounced over time.
Brushless Motor
Brushless motors are quieter by design. Without mechanical contact, the primary noise sources are air movement and minor vibrations, making them a better choice for noise-sensitive applications like medical equipment and consumer electronics.
3.1.5 Commutation
Brushed Motor
Brushed motors rely on a mechanical commutation system. The brushes physically transfer current to the commutator, creating a magnetic field that rotates the armature. This method is straightforward but comes with wear and tear due to constant friction between brushes and the commutator.
Brushless Motor
In contrast, brushless motors use electronic commutation, managed by a controller. The controller precisely switches the current in the stator windings to generate a rotating magnetic field, which drives the rotor. This approach eliminates mechanical friction, resulting in smoother operation and greater reliability.
3.1.6 Efficiency
Brushed Motor
Efficiency is where brushless motors excel. Brushed motors lose energy as heat due to friction and electrical resistance in the brushes and commutator. This limits their efficiency, particularly during prolonged use.
Brushless Motor
Brushless motors, with no physical contact between components, experience minimal energy loss. The precise electronic control further optimizes power delivery, making them up to 85–90% efficient, compared to 75–80% for brushed motors
(source: ScienceDirect).
3.1.7 Speed Regulation
Brushed Motor
Brushed motors regulate speed by varying the input voltage. While this method is straightforward, it has significant limitations in terms of precision and responsiveness. The speed is directly tied to the voltage, making fine adjustments challenging. Small changes in voltage often result in inconsistent speed control, reducing accuracy. Moreover, the physical contact between brushes and the commutator introduces friction and wear, especially at higher speeds. Over time, this wear leads to fluctuations in speed regulation. Additionally, when the voltage changes, the mechanical components need time to adjust the current flow, resulting in slower response times. The friction also generates heat, further destabilizing performance during prolonged use or variable-speed operations.
Brushless Motor
In contrast, brushless motors excel in speed regulation due to their advanced electronic control systems. The electronic controller precisely switches current through the stator windings, allowing for accurate and seamless speed adjustments. Feedback from sensors, such as Hall-effect sensors, ensures that the rotor’s position is continuously monitored. This real-time data enables the controller to make rapid adjustments, resulting in highly responsive and stable speed control. Additionally, the lack of physical contact between components eliminates friction, reducing energy loss and heat generation, which ensures consistent performance even at variable speeds.
While brushed motors are suitable for basic applications where precision is not critical, brushless motors dominate in scenarios that demand high responsiveness and accurate speed regulation. Their advanced control systems make them the go-to choice for applications like drones, robotics, and electric vehicles, where precise speed control is essential.
3.1.8 Cost
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Initial Cost
Brushed motors are cheaper to manufacture and purchase because of their simpler design. This makes them a cost-effective choice for budget-friendly applications.
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Maintenance Cost
Over time, brushed motors incur higher costs due to frequent maintenance. Replacing brushes and commutators can add up, especially in continuous-use scenarios.
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Lifetime Cost
Brushless motors are pricier upfront, primarily due to the controller. However, their longer lifespan and minimal maintenance requirements make them more economical in the long run. For example, in industrial applications, the lower energy consumption and reduced downtime of brushless motors often offset the higher initial expense.
In a word, Advantages and Disadvantages of Brushed Motors
Advantages
Brushed motors shine with their simplicity. Their design is straightforward, making them easy to manufacture and repair. This also keeps costs low, which is why they’re often found in budget-friendly devices. Maintenance is typically uncomplicated—replacing worn-out brushes is all it takes to get them running smoothly again.
Disadvantages
However, this simplicity comes at a cost. Brushed motors are noisier during operation due to physical contact between the brushes and the commutator. This same contact leads to wear and tear, meaning brushes and commutators need frequent replacement. As a result, brushed motors usually have a shorter lifespan compared to their brushless counterparts.
Advantages and Disadvantages of Brushless Motors
Advantages
Brushless motors are the efficiency kings. They generate less heat, operate more quietly, and require virtually no maintenance since there are no brushes to replace. This design also means they last significantly longer than brushed motors. The advanced electronic controller ensures smooth operation and precise speed control, making them ideal for high-performance applications like drones and electric vehicles.
Disadvantages
The downside? Brushless motors come with a higher upfront cost due to their sophisticated design and the need for an electronic controller. Their complexity also means repairs require specialized knowledge, making DIY fixes challenging.
| Feature | Brushed Motors | Brushless Motors |
|---|---|---|
| Lifetime | Shorter lifespan due to wear on brushes and commutator. | Long lifespan with no mechanical wear components. |
| Speed and Acceleration | Limited by mechanical friction; slower response. | Faster response; precise speed control. |
| Electrical Noise | Significant noise from brush-commutator contact. | Minimal electrical noise; no arcing. |
| Acoustic Noise | Louder due to physical friction and wear. | Quieter due to no mechanical contact. |
| Commutation | Mechanical, relying on brushes and commutator. | Electronic, using a controller for precise switching. |
| Efficiency | 75-80% efficient; energy lost as heat and friction. | 85-90% efficient; minimal energy loss. |
| Speed Regulation | Basic control by varying voltage; less precise. | Highly precise speed control through electronic systems. |
| Energy Efficiency | Higher energy losses due to friction and heat. | Lower energy consumption; highly efficient. |
| Cost | Low initial cost but higher maintenance costs over time. | High initial cost but lower maintenance and lifetime costs. |
Video Resources
Quiz: Test Your Knowledge of Part 2: "The Definitions and Structures of Brushed Motors & Brushless Motors"
3. Applications
Common Uses of Brushed Motors
Photo: This is a brushed motor.
Brushed motors are ideal for applications where cost and simplicity are key. They’re commonly used in:
- Power Tools: Drills, saws, and other tools benefit from the motor’s affordability and ease of repair.
- Small Household Appliances: Devices like blenders, fans, and vacuum cleaners often rely on brushed motors due to their low manufacturing costs.
Brushed motors are a great fit for intermittent use and applications where high precision isn’t essential.
Common Uses of Brushless Motors
Brushless motors dominate in fields where efficiency, precision, and longevity matter most. These include:
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Drones
Their lightweight design and precise speed control make them perfect for flight stability and maneuverability.
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Electric Vehicles (EVs)
With high efficiency and minimal maintenance, brushless motors are the heart of modern EV propulsion systems.
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Precision Equipment
Devices like 3D printers and robotic arms depend on the smooth operation and accuracy of brushless motors.
4. Latest Technologies and Market Trends
Innovations in Materials
The use of rare earth magnets, such as neodymium, has revolutionized motor performance. These magnets provide stronger magnetic fields, enabling brushless motors to generate higher torque while remaining compact. This innovation is especially beneficial for applications like drones and electric vehicles, where size and weight are critical. Additionally, advancements in motor windings, such as copper-clad aluminum, have improved thermal efficiency and reduced weight, further enhancing motor performance.
Advances in Control Algorithms
Modern brushless motors benefit greatly from advancements in sensorless control algorithms. These algorithms eliminate the need for physical sensors, reducing costs and improving reliability. By precisely controlling the timing and flow of current, these systems ensure smoother operation, faster response, and higher energy efficiency.
For instance, sensorless controllers are widely used in drones, allowing for precise navigation without adding extra hardware.
Trends Toward Environmentally Friendly Motor Development
As sustainability becomes a global priority, motor manufacturers are focusing on environmentally friendly designs.
Brushless motors are leading the charge with minimal energy loss, aligning with stricter energy regulations worldwide.
Companies are developing motors using materials that are easier to recycle, reducing environmental impact.
By eliminating wear-and-tear components like brushes, motors now last longer, reducing waste from replacements.
One notable trend is the shift toward motors in renewable energy applications, such as wind turbines, where brushless motors ensure maximum efficiency and reliability.
7. FAQs
Is brushless better than brushed?
It depends on your needs. Brushless motors are generally better for applications requiring high efficiency, longevity, and quiet operation. Brushed motors, however, are more affordable and suitable for simpler, cost-sensitive applications.
Do brushless motors last longer than brushed?
Yes, brushless motors last significantly longer because they don’t have brushes or commutators that wear out. Their electronic design minimizes friction and heat, making them more durable and low-maintenance.
Why are brushed motors so inefficient?
Brushed motors lose energy due to friction between the brushes and commutator. This friction generates heat, which reduces overall efficiency. Additionally, the constant contact creates wear and tear, further affecting performance over time.
Why are brushless motors noisy?
Brushless motors are generally much quieter than brushed motors. However, slight noise can occur due to vibrations from the rotor or air movement around the motor. This noise is typically minimal compared to the mechanical noise in brushed motors.
Why do brushless motors have three wires?
Brushless motors often have three wires because they use a three-phase design. These wires supply current to the stator coils in sequences, creating a rotating magnetic field that drives the rotor. This setup ensures smoother operation and higher efficiency.
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