Brushed vs Brushless Motors

 Contents List

1. Introduction
2. What Is a Brushed DC Motor?
3. How Does a Brushed Motor Work?
4. What Is a Brushless DC Motor?
5. How Does a Brushless Motor Work?
6. Brushed vs Brushless Motor: Main Differences
7. Advantages and Limitations of Brushed Motors
8. Advantages and Limitations of Brushless Motors
9. Efficiency, Speed, Torque, and Motor Life
10. Motor Control and Driver Requirements
11. Noise, EMI, Maintenance, and Reliability
12. Brushed vs Brushless Motors: Applications
13. How to Choose the Right Motor?
14. Brushed vs Brushless Motors: Comparison Table
15. Frequently Asked Questions
16. Conclusion

Time reading is 20min.

1. Introduction

Brushed Motors and Brushless Motors are two important motor technologies used in electronics, robotics, automation, appliances, power tools, cooling systems, vehicles, and many other applications.

At first glance, both types perform the same basic job: they convert electrical energy into mechanical rotation. The major difference is how electrical current is switched through the motor windings.

A brushed DC motor uses mechanical commutation, where brushes and a commutator switch current through the rotating armature windings.

A brushless DC motor, commonly called a BLDC motor, removes the mechanical brushes and commutator. Instead, an electronic controller switches current through stationary stator windings according to the rotor position.

Striation, control requirements, efficiency, operating life, maintenance, noise, and cost.

Neither technology is automatically the best choice for every application.

A simple brushed motor may be the better solution when low cost, simple control, and easy integration are the main priorities. A brushless motor is often preferable when long operating life, high efficiency, high speed, lower maintenance, and precise electronic control are important.

The purpose of this article is to explain the differences between brushed and brushless motors in a way that is useful for beginners, hobbyists, technicians, and engineers.

2. What Is a Brushed DC Motor?

A Brushed DC Motor is an electric motor that uses brushes and a mechanical commutator to switch electrical current through the motor’s rotating windings.

 

A conventional brushed DC motor contains several fundamental parts:

• Stator
• Rotor or armature
• Rotor windings
• Permanent magnets or field windings
• Brushes
• Commutator
• Shaft
• Bearings

In a common permanent-magnet brushed DC motor, the permanent magnets create the stationary magnetic field while the rotor contains the energized windings.

Microchip’s technical reference on brushed DC motors identifies the stator, rotor, brushes, and commutator as the basic components of a conventional brushed motor.

The brushes provide electrical contact with the rotating commutator. As the rotor turns, the commutator changes which rotor windings receive current.

This mechanical switching process is called commutation.

3. How Does a Brushed Motor Work?

The operating principle can be understood in a few steps.

 

Step 1: Electrical Power Is Applied

• A DC voltage is applied to the motor terminals.
• Current flows through the brushes and commutator into the appropriate rotor winding.

Step 2: A Magnetic Field Is Produced

• Current flowing through the rotor winding produces a magnetic field.
• The interaction between this magnetic field and the stator’s magnetic field produces electromagnetic torque.
• The torque causes the rotor to rotate.

Step 3: The Commutator Changes the Current Path

• If the current remained in the same rotor winding indefinitely, the rotor would eventually reach a position where continuous rotation could no longer be maintained.
• The commutator mechanically changes the electrical connection as the rotor turns.
• The brushes remain in contact with the commutator while the commutator segments switch the current between the rotor windings.

Step 4: Continuous Rotation Is Produced

This repeated mechanical commutation maintains torque in the desired direction and allows the motor to continue rotating.

This is one of the major advantages of a brushed DC motor:

the motor can perform its own commutation mechanically without requiring a separate electronic commutation controller.

A suitable DC supply can therefore drive a basic brushed motor with relatively simple electronics.

4. What Is a Brushless DC Motor?

A Brushless DC Motor (BLDC) removes the brushes and mechanical commutator used in a conventional brushed motor.

Instead, the motor uses:

• Permanent magnets on the rotor
• Windings on the stator
• Electronic switching circuitry
• A motor controller or driver
• Position feedback or position estimation, depending on the design

The basic arrangement is effectively reversed compared with a conventional permanent-magnet brushed motor: the permanent magnets are typically located on the rotor, while the electromagnetic windings are located on the stationary stator

Because the rotor does not need an electrical connection through brushes, the controller can energize the stationary windings electronically.

This eliminates mechanical brush wear and allows the motor to operate at high speed with reduced mechanical commutation losses.

However, a BLDC motor normally requires appropriate electronic drive circuitry. A bare BLDC motor cannot simply be connected to a DC power supply and expected to operate like a basic two-wire brushed motor.

5. How Does a Brushless Motor Work?

The operating principle of a BLDC motor is based on electronic commutation.

Step 1: The Controller Receives Power

• The electronic driver receives DC power from a suitable power source.
• The controller contains switching devices, commonly MOSFETs, that control current through the motor phases.

Step 2: The Controller Determines Rotor Position

The controller needs to know when to switch the motor phases.

This can be accomplished using:

• Hall-effect sensors
• Encoders
• Sensorless back-EMF detection
• Other rotor-position estimation techniques

Hall sensors are commonly used to provide direct rotor-position information. Sensorless systems can estimate rotor position from electrical signals generated by the rotating motor.

Step 3: The Controller Energizes the Stator Windings

• The controller switches current through the stator windings in a particular sequence.
• The energized stator windings create a rotating magnetic field.
• The permanent magnets on the rotor follow this changing magnetic field, causing the rotor to turn.

Step 4: Electronic Commutation Continues

• As the rotor moves, the controller changes the energized phases.
• For a common three-phase BLDC motor, six-step commutation divides one electrical cycle into six 60-degree electrical sectors. A three-phase inverter is commonly used to perform the switching.
• More advanced BLDC/PMSM systems can use techniques such as Field-Oriented Control (FOC) to achieve smoother torque and highly controlled operation.

6. Brushed vs Brushless Motor: Main Differences

The fundamental difference is the location and method of commutation.

Mechanical vs Electronic Commutation

A brushed motor uses:   Brushes + commutator → mechanical commutation

A brushless motor uses:   Controller + switching electronics → electronic commutation

This single difference leads to many of the practical differences between the two technologies.

Motor Construction

In a typical brushed permanent-magnet motor:

• Permanent magnets → stator
• Windings → rotor

In a typical BLDC motor:

• Windings → stator
• Permanent magnets → rotor

The brushless arrangement places the windings on the stationary part of the motor, which simplifies heat removal from the windings and eliminates the need to transfer current through sliding contacts.

Electrical Connections

• A simple brushed DC motor commonly has two main power terminals.
• A BLDC motor commonly has three motor phase connections for a three-phase design, plus possible connections for Hall sensors or other feedback devices.
• However, actual motor configurations vary, so the number of wires should not be used alone to identify a motor type.

7. Advantages and Limitations of Brushed Motors

Brushed motors remain useful because their simplicity can be a major engineering advantage.

Advantages of Brushed Motors

Simple control

• A basic brushed DC motor can be driven using a relatively simple circuit.
• Speed can often be controlled by adjusting the applied voltage or using PWM through an appropriate driver.

Low initial cost

Brushed motors and their drive electronics can be inexpensive, particularly for small applications.

Easy to use 

A basic two-wire brushed motor is convenient for beginners and simple projects.

Good starting torque

Brushed DC motors can provide useful starting torque and straightforward speed control.

Widely available

• Brushed motors are available in many sizes, voltage ratings, speeds, and gearmotor configurations.
• Microchip and Texas Instruments both highlight the simplicity and low cost of brushed DC motor systems as important advantages.

Limitations of Brushed Motors

Brush wear

The brushes physically contact the commutator and therefore wear over time.

Commutator wear

The mechanical commutator also experiences wear.

Electrical noise

Mechanical commutation can produce electrical noise and electromagnetic interference.

Sparking

Brush commutation can produce sparks, which limits suitability for certain environments.

Maintenance

Depending on the motor and operating conditions, brushes may eventually need inspection or replacement.

Limited high-speed operation

• The mechanical commutation system can become a limiting factor at high rotational speeds.
• Texas Instruments specifically identifies brush lifetime, noise, sparking, and potential EMI concerns among the disadvantages of brushed DC motors.

8. Advantages and Limitations of Brushless Motors

Brushless motors eliminate mechanical brushes, but this does not mean they eliminate every possible source of wear or failure.

Advantages of Brushless Motors

Longer operating life

• Because there are no brushes rubbing against a commutator, brush wear is eliminated.
• Bearing wear and other mechanical limitations still exist, but brush replacement is no longer required.

High efficiency

• BLDC motors can provide high efficiency because they avoid mechanical brush contact losses and can use sophisticated electronic control.
• However, efficiency depends on the motor design, operating point, controller, load, and commutation method.
• It is therefore inaccurate to assume that every brushless motor is automatically more efficient than every brushed motor.

High-speed capability

The absence of mechanical brushes and a commutator makes brushless designs particularly suitable for high-speed applications.

Lower maintenance

There are no brushes to replace.

Lower mechanical noise

Removing the mechanical brush contact eliminates brush friction and commutation noise, although a brushless system can still generate acoustic noise from electromagnetic forces, bearings, airflow, PWM, and other mechanisms.

Good controllability

Electronic commutation allows the designer to implement advanced speed, torque, and position control.

High power density

BLDC motors can provide a high power-to-size ratio, making them useful when space and weight are important.

Limitations of Brushless Motors

Requires electronic control

A BLDC motor normally requires a suitable driver or controller.

Higher system complexity

The motor, controller, feedback system, and firmware may all need to be considered as part of the complete system.

Higher initial system cost

The motor itself may not be the only cost consideration. The electronic controller and associated circuitry also contribute to the overall system cost.

Control design can be more complicated

• Advanced applications may require careful commutation, current control, rotor-position estimation, PWM configuration, protection, and thermal management.
• Microchip’s BLDC documentation demonstrates that control can range from relatively simple six-step commutation to more sophisticated control architectures such as FOC.

9. Efficiency, Speed, Torque, and Motor Life

One of the most common mistakes when comparing motors is assuming that one technology always wins every performance category.

The actual result depends on the motor’s construction, winding, magnet system, controller, load, operating speed, temperature, and duty cycle.

Efficiency

• Brushless motors are often selected for high-efficiency applications.
• The absence of brush friction and mechanical commutation can reduce losses, while electronic control allows the operating point to be optimized.
• However, motor efficiency should always be evaluated using actual motor performance data rather than technology labels alone.

Speed

Brushless motors are generally well suited to high-speed operation because there are no brushes and commutator surfaces whose mechanical contact limits operation.

The achievable speed is still limited by factors such as:

• Bearing capability
• Rotor construction
• Magnet limitations
• Winding characteristics
• Mechanical balance
• Controller capability
• Load
• Thermal conditions

Torque

• Both technologies can provide useful torque.
• BLDC systems can provide high torque relative to their size and can offer strong dynamic performance when correctly controlled.
• But torque cannot be compared accurately simply by saying “brushless has more torque.”
• The actual torque depends on motor geometry, winding, current, magnetic circuit, speed, thermal limits, and controller.

Operating Life

• The absence of brushes gives brushless motors a major advantage in applications requiring long continuous operation.
• In a brushed motor, brush and commutator wear eventually become important limitations.
• In a brushless motor, the bearings and other mechanical components still wear.
• Maxon notes that typical operating life can vary substantially between technologies and motor constructions, reinforcing the importance of evaluating the actual motor specification rather than relying on a universal lifetime number.

10. Motor Control and Driver Requirements

The motor and its driver should be considered together.

Driving a Brushed DC Motor

A basic brushed DC motor can often be controlled using:  DC supply → Motor

• For direction control, an H-bridge can be used.
• For speed control, PWM can be applied through a suitable motor driver.
• A microcontroller can therefore control a brushed motor using relatively simple hardware.

Driving a Brushless Motor

A typical BLDC system requires:  DC supply → BLDC driver/inverter → Motor

• The controller determines when and how the motor phases are energized.
• A three-phase BLDC system commonly uses a three-phase bridge consisting of switching devices such as MOSFETs.

The controller may use:

• Hall sensors
• Back-EMF sensing
• Encoders
• Current sensing
• PWM
• Position estimation
• Closed-loop speed control

Microchip describes six-step, sensor-based, sensor less, and more advanced control approaches for BLDC motors.

Why the Controller Matters

• The performance of a brushless motor is strongly influenced by its controller.
• Two systems using the same motor can behave differently if they use different control strategies.
• For example, six-step commutation is relatively simple but can produce more torque ripple, while advanced FOC can provide smoother torque and precise control.

11. Noise, EMI, Maintenance, and Reliability

• Motor selection is not only about speed and torque.
• Environmental and maintenance requirements can be equally important.

Electrical Noise

Brushed motors can generate electrical noise because of mechanical commutation and brush contact.

This can be an issue in systems containing:

• Microcontrollers
• Sensors
• Audio circuits
• Communication equipment
• Precision measurement electronics

Appropriate filtering and suppression techniques can reduce these effects.

Electromagnetic Interference

• Brush arcing and rapid current changes can contribute to electromagnetic interference.
• Brushless systems eliminate brush arcing, but they are not automatically free from EMI.
• Fast switching of MOSFETs and PWM currents can generate conducted and radiated electromagnetic noise.

Therefore, BLDC systems still require good:

• PCB layout
• Grounding
• Wiring
• Decoupling
• Filtering
• Switching control
• EMC design

Mechanical Noise

• A brushed motor can produce audible noise from brush and commutator contact.
• A BLDC motor can be quieter mechanically, but the overall system may still generate acoustic noise from electromagnetic torque ripple, bearings, PWM, and mechanical structure.

Maintenance

• A brushed motor may require brush and commutator maintenance depending on its construction and duty cycle.
• A brushless motor does not require brush replacement, which makes it attractive for systems where maintenance access is difficult.
• Oriental Motor also highlights the longer service life and reduced maintenance associated with brushless designs because there are no brushes to wear.

12. Brushed vs Brushless Motors: Applications

Both motor technologies remain relevant because their strengths are different.

Common Brushed Motor Applications

Brushed motors are often suitable for:

• Small toys
• Simple robotics
• Low-cost mechanisms
• Small pumps
• Actuators
• Basic fans
• Simple gearmotors
• Automotive mechanisms
• Educational projects
• Battery-powered devices

They are especially attractive when simple control and low system cost are important.

Common Brushless Motor Applications

BLDC motors are widely used in:

• Computer cooling fans
• Drones
• Electric bicycles
• Electric vehicles
• Power tools
• Robotics
• Industrial automation
• Pumps
• Compressors
• Appliances
• Medical equipment
• Aerospace systems

Microchip identifies appliances, automotive systems, aerospace, consumer electronics, medical systems, industrial automation, and instrumentation among BLDC applications.

Why Application Requirements Matter

For example, a small educational robot may benefit from the simplicity of a brushed gearmotor.

A drone, however, typically benefits from the efficiency, speed, power density, and electronic controllability of a brushless motor.

The correct question is therefore not:  “Which motor is better?”

It is:   “Which motor technology best satisfies the requirements of this application?”

13. How to Choose the Right Motor?

When selecting between a brushed and brushless motor, consider the complete system rather than the motor alone.

Required Voltage

Determine the available supply voltage.

For example:

• 5 V
• 12 V
• 24 V
• 48 V

The motor’s rated voltage must be compatible with the intended system.

Required Speed

• Determine the required operating speed in RPM.
• Do not select a motor based only on its no-load speed.
• Consider the speed under the actual mechanical load.

Required Torque

• Determine the torque needed to move the load.
• Also consider starting torque and transient loads.
• A motor that can reach the required RPM without sufficient load torque is not an appropriate choice.

Duty Cycle

Ask how the motor will operate:

• Intermittently
• Continuously
• At low speed
• At high speed
• With frequent starts and stops

A motor operating continuously for thousands of hours has different requirements from a motor operating for a few seconds at a time.

Operating Life

• If long operating life and minimal maintenance are priorities, a brushless motor may be more appropriate.
• For a short-duration or easily serviceable application, a brushed motor may provide a better cost-to-performance ratio.

Controller Requirements

• A brushed motor can often use a relatively simple driver.
• A brushless motor requires appropriate commutation electronics.

Consider the additional:

• Driver cost
• PCB space
• Software
• Sensors
• Current sensing
• Protection
• Control complexity

Size and Weight

When space or weight is restricted, brushless motors can be attractive because of their high power density.

Noise and EMI

• If the motor is installed near sensitive electronics, evaluate electrical and acoustic noise.
• Do not assume that simply choosing a brushless motor eliminates all EMI problems.

Cost

• Consider total system cost, not just the motor price.
• For a brushed system:  Motor + driver + power supply
• For a brushless system:  Motor + controller + sensors/feedback + power supply
• The actual cost difference depends heavily on the application.

Availability and Serviceability

• For a product intended for easy field maintenance, a brushed motor may be practical.
• For equipment that is difficult to access after installation, a brushless motor’s long operating life can be more valuable.

14. Brushed vs Brushless Motors: Comparison Table

The table provides a general engineering comparison. Actual performance depends on the specific motor, controller, load, operating point, and mechanical design. In particular, efficiency, torque, speed, and lifetime should be verified from the manufacturer’s specifications rather than assumed solely from motor type.

15. Frequently Asked Questions

Is a brushless motor better than a brushed motor?

• Not in every application.
• Brushless motors generally offer advantages in operating life, maintenance, high-speed operation, efficiency potential, and electronic control.
• Brushed motors can be better when simplicity, low cost, and easy control are more important.

Can I connect a brushless motor directly to a DC power supply?

• A typical three-phase BLDC motor should not be treated like a simple two-wire brushed DC motor.
• It normally requires an appropriate electronic controller that performs commutation.

Can I control a brushed motor with PWM?

• Yes. PWM is commonly used to control the average voltage delivered to a brushed DC motor through an appropriate motor driver.
• The driver must be correctly rated for the motor’s voltage, current, and operating conditions.

Do brushless motors have brushes at all?

• No. A brushless motor does not use mechanical brushes for commutation.
• Instead, electronic circuitry switches current through the motor windings.

Do brushless motors last forever?

No.

Removing brushes eliminates one major wear mechanism, but bearings, insulation, magnets, electronics, and other mechanical or electrical components can still fail.

Which motor is more efficient?

• Brushless motors are often highly efficient, but there is no universal answer.
• Efficiency depends on motor construction, winding design, operating speed, load, controller, and operating point.
• Specialized brushed motors can outperform some brushless designs under particular conditions.

Which motor is better for robotics?

• It depends on the robot.
• A small, inexpensive robot may benefit from a brushed DC gearmotor because it is simple to control.
• A high-performance robot requiring high efficiency, high speed, precise control, or long operating life may benefit from a brushless motor.

Which motor is better for a beginner electronics project?

• A small brushed DC motor is usually easier for beginners because it can be controlled with relatively simple electronics.
• Once the basic principles are understood, a BLDC motor is an excellent next step for learning motor drivers, Hall sensors, PWM, commutation, and embedded control.

Why do BLDC motors need a controller?

• The controller replaces the mechanical commutator.
• It determines which stator windings should be energized and when, based on the desired motor operation and available rotor-position information.

Can a brushless motor have Hall sensors?

Yes.

• Many BLDC motors use Hall-effect sensors to provide rotor-position information to the controller.
• Other systems can operate without physical position sensors by estimating rotor position using electrical signals such as back EMF.

16. Conclusion

Brushed and brushless motors are both valuable motor technologies, but they solve different engineering requirements.

The key difference is commutation.

A brushed motor uses:   Brushes + commutator + mechanical switching

A brushless motor uses:   Electronic controller + switching devices + electronic commutation

Brushed motors are attractive because they are simple, inexpensive, widely available, and easy to control.

Brushless motors are attractive because they eliminate brush wear and can provide long operating life, high efficiency, high-speed operation, high power density, and advanced electronic control.

However, choosing a motor should never be based on the assumption that “brushless is always better.”

A proper selection should consider:  Voltage → Speed → Torque → Duty Cycle → Efficiency → Lifetime → Controller → Size → Noise → Cost → Application

For a simple, low-cost project, a brushed motor may be exactly the right engineering choice.

For a demanding application requiring long service life, high speed, high efficiency, precise control, or minimal maintenance, a brushless motor may be the better solution.

The most important lesson is to evaluate the complete motor system, including the motor, driver, power supply, mechanical load, control method, thermal conditions, and expected operating life.