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What is the Difference Between Brushed and Brushless DC Motors?

Differences between Brushed and Brushless DC Motors

When we speak of motors, our mind paints a picture of a DC motor that works on a very simple principle.

But did you know? There are two types of DC motors that are, brushed and brushless DC motors.

You might ask, “What is the difference between brushed and brushless DC motors?”

The differences between brushless and brushed DC motors are many. Including structure, working principle, control method, lifetime, and more. But the significant difference between the two motors lies in the use of brushes. Brushed DC motors use brushes to deliver electricity while brushless motors don’t.

In this article, I will list the differences between brushed and brushless DC motors. 

So, sit back and relax!

What is a DC Motor?

 

Brushed Dc Motors

By definition, a DC motor is an electrical device that converts electrical energy into mechanical energy. Thus, any motor which operates using direct current is a DC motor.

There are two common types of DC motors:

  1. Brushed DC motors
  2. Brushless DC motors

Brushed DC Motor

 

We have been using brushed DC motors for as long as 100 years in commercial and industrial applications. You can change the speed of brushed motors by altering the voltage or strength of the magnetic field. The ease of control makes brushed DC motors very useful in many applications.

Brushed motors comprise four essential components: 

  1. Stator
  2. Rotor
  3. Brushes
  4. Commutator

Brushed Motor Structure

Brushless DC Motor

Brushless DC motors are also called ECM or EC motors (Electronically commutated motors). We use permanent magnets and controllable electromagnets to spin the rotor in brushless motors.

Brushless motors come in two forms: 

  1. Inrunner – The stator is present outside of the rotor. 
  2. Outrunner – The stator is present inside the rotor.

Inrunner And Outrunner Brushless Dc Motor

What is the Difference Between Brushed and Brushless DC Motors?

 

Here are some of the fundamental differences between Brushed and Brushless DC motors.

Motor Structure

 

The construction of Brushed DC motors and Brushless DC motors vary. Using a mechanical commutator instead of an electric switch is the main difference. Hence, in a BLDC motor, the rotor and a magnetic field by the stator revolve at the same frequency.

Brushed DC Motors

 

A brushed DC motor consists of brushes, magnets, armature winding, and a physical commutator. The commutator reverses the current and creates a torque in a single direction. A brushed DC motor has two main components:

  1. Stator (containing magnets and brushes)
  2. Rotor (armature winding and commutator)

Brushless DC Motors

 

Brushless DC motors are also called synchronous DC motors. They do not have brushes or a commutator. In a brushless DC motor, the rotor has magnets, and the stator has armature windings. An electronic servo mechanism replaces the commutators. It detects and adjusts the angle of the rotor.

Brushless Dc Motor Structure

Working Principle

 

Both the motors work on a principle of Lorentz Law that states,

“The current-carrying conductor placed in a magnetic and electric field experience a force.”

The force is Lorentz Force.

But the working of brushless and brushed DC motors differs due to their motor structures.

Brushed Motor

 

The brushed DC motors use permanent magnets inside their outer body. These magnets are stationary and called the stator. On the inside, it uses a rotating armature. The armature contains an electromagnet called the rotor.

The rotor in Brushed DC motors spins at 180° when the current flows to the armature. When you want to travel the current beyond 180°, the electromagnet poles must flip.

Hence, the brushes contact the stator that flips the magnetic field. It allows the transfer of electricity from the power source to the motor and enables the rotor to spin at 360°.

The spinning of the motor creates natural friction. It weakens the brushes and wastes energy within the motor.

Brushless Motor

 

In Brushless DC motors, a circuit board replaces the brushes and commutator. A ring of electromagnets surrounds the magnetic field. And conventional magnets surround the shafts. The electromagnets in brushless DC motors are stationary. Thus, allow the shaft and magnetic field to rotate within the ring. Due to the stationary behavior of electromagnets, electricity doesn’t reach them.

In short, Brushless DC motors use distinct magnets. Also, they don’t need brushes for the transfer of electricity. Because of this reason, a brushless DC motor is clean and efficient.

Brushless Motor Pcb

Speed Regulation Method

 

The speed regulation for brushed and brushless motors is the same, i.e., via voltage regulation.

The only difference is brushless motors feature a digital control via electronic commutation. Whereas, brushed DC motors use metals or carbon brushes.

Brushed Motor

 

The brushes and commutator in a brushed DC motor limit the rotational speed. When you run a brushed DC motor at high speed, the brushes that contact the commutator become unstable. Hence, brush arching increases.

Most brushed DC motors have large rotational inertia by using laminated iron in the rotor. It restricts the acceleration and deceleration rate of the DC motor. In short, a Brushed DC motors’ speed range is lower than a Brushless DC motor.

Motor Rotor

Brushless Motor

 

The speed performance of a brushless motor is high compared to brushed DC motors. The performance is due to the absence of brushes.

To control the speed of a brushless DC motor, the voltage supply remains unaltered. Yet, we should change the control signal of ESC and the switching rate of the high-power MOS tube. It is to determine the speed change.

In short, we will regulate the speed by changing the frequency. 

Brushless Motor Esc

Commutation

 

A brushed DC motor uses brushes for the current flow to the motor winding via mechanical commutation.

But, a brushless DC motor uses electrical commutation to deliver the current.

Rotor Inertia

 

The rotor inertia of a brushless motor is low since it uses permanent magnets on the rotor that improve its dynamic response. But for a brushed motor, the rotor inertia is high, limiting the dynamic characteristics of the machine.

Also, you can build a brushless motor with strong rare earth magnets on the rotor to reduce rotational inertia. But it would cost more.

Output Power or Frame Size

 

Brushless electric motors have better thermal characteristics. Due to this, they have a condensed frame size. Also, the heat dissipation of brushless electric motors is more reasonable than a brushed motor as it has windings on the stator.

The heat dissipation through the armature increases the temperature in brushed DC motors. It limits the performance of output power or frame size.

Manufacturing Cost

 

The use of permanent magnets in brushless electric motors makes them expensive compared to the brushed motor.

Maintenance

 

Dc Motor Maintenance

When it comes to maintenance, brushed and brushless motors need yearly maintenance. But, brushes in brushed motors require frequent maintenance compared to brushless motors.

Noise

 

We all know that DC motors make noise. But the noise of a brushless motor is much better than a brushed motor. Brushed motors generate mechanical noise by friction between the brushes and commutator during operation. Also, the arcs in brushes cause Electromagnetic Interference (EMI) in the nearby equipment. While brushless motors do not have brushes, so brushless motors are often used in applications with high noise requirements. For example, motorized curtains, which require very silence.

Life Expectancy

 

Brushed motors use carbon brushes that wear out in a thousand hours. Thus, the need to replace brushes occurs frequently. On the flip side, brushless DC motors are free of brushes. Hence chances of wear and tear are close to none.

Instead, you should often clean the dirt and other pollutants on brushless motors.

Starting Torque and Response

 

The starting torque and response in brushless DC motors are flat. It means you can operate it at all speeds within the rated load. Yet, you might experience strong vibrations and humming sounds when starting the motor.

For brushed motors, the starting torque and response are rather flat with smooth variable speed.

Brushed VS. Brushless Motors: Advantages and Disadvantages

 

Advantages And Disadvantages

Since we already discussed the differences between Brushed and Brushless DC motors. Let’s have a look at the advantages and disadvantages that they offer.

Advantages of Brushed DC motors

 
  1. Low Cost. Brushed DC motors use brushes and a commutator, so they are cost-effective
  2. High starting torque. Brushed DC motors are an excellent choice for applications that need a high starting torque, such as caravan movers. Hence, they are prevalent in industrial environments.
  3. Rebuilt to extend life. You can change or rebuild new brushes to extend the life of your DC motor.
  4. Ideal for Extreme Conditions. Brushed DC motors are ideal for extreme environments. Because they have two-wire control and a lack of electronics.

Disadvantages of Brushed DC motors

 
  1. Frequent Maintenance. The frequent use of carbon brushes results in friction. Thus, they will wear and tear often and need regular upkeep and maintenance.
  2. Low speed. Brushed motors cannot regulate the accurate speed. Though they can control speed through voltage only, so the speed range is lower.
  3. Poor heat dissipation. The internal rotor construction results in poor heat dissipation.
  4. Lifetime. They have a short lifetime due to the frequent use of brushes. Miniature brush motors have a lifespan of around 100 to 500 hours. Yet, in industrial applications, they have a lifespan of approximately 5000 hours.
  5. Flat torque. The brush friction will increase when you run a brushed DC motor at higher speeds. It reduces useful torque.
  6. Generate sparks. Brushless DC motors generate sparks. Thus, not suitable for applications where there is a risk of explosion.

Advantages of Brushless DC motors

  1. High Efficiency. BLDC motors have zero excitation or mechanical loss, no brush friction, and no sparks. Hence, they are more efficient.
  2. Lifetime. They have a lifespan of around 10,000 to 20,000 hours due to the absence of brushes. Brushless Dc motors are more reliable and durable than brushed motors.
  3. Low Noise. Brushless DC motors make less noise. Because there is no friction between the brushes and commutator. We use Brushless motors in applications with high noise requirements, including motorized curtains.
  4. Smooth Operation. A brushless DC motor gives resistance to bumps, vibrations. Hence, it provides smooth operation.
  5. Speed control. The built-in PCB and hall sensors in Brushless motors can control motor speed, the direction of rotation, and braking functions.
  6. Lightweight. Brushless DC motors come in small sizes. Hence, light-weight and compact
  7. Runs at low or no load. They feature a no-load current. Thus, it provides smooth operation at low or no load.

Brushless Dc Motor

Disadvantages of Brushless DC motors

 
  1. High cost. Brushless DC motors use sophisticated components for electrical control. Also, the rare-earth permanent magnet is very expensive than other permanent magnets.
  2. Safety. The rare earth permanent magnets might attract scattered metal objects. Thus, the manufacturing process of brushless DC motors is dangerous.
  3. Requires electronic speed Control. The current in DC brushless motors cannot flow straight to the electromagnets. Thus, it requires an electronic speed controller.
  4. Complex structure. The electronic control and electromagnets turn the wiring and operation of BLDC difficult.

Manufacturing Costs

Application Fields of DC Brushed and Brushless motors

 

We use brushed and brushless motors in a wide range of applications. From industrial areas to household appliances, these motors provide unmatched feasibility.

Brushed DC Motor Applications

 

Several household appliances and automobiles use brushed DC motors. Because of their low cost, fixed and variable speed drives, and low or high power.

We use brushed DC motor in practical applications like:

  1. Paper machines
  2. Cranes 
  3. Sewing machines
  4. Power tools 
  5. Rolling mills
  6. Kids toys
  7. Robots
  8. RC cars
  9. Electric toothbrush

Power Tools

Brushless DC Motor Application

 

Brushless DC motors have almost replaced brushed motors. Because of their high efficiency, controllability, and longer lifespan. Today, brushless motors are available everywhere, especially in devices that run nonstop.

The most common practical applications of brushless DC motors are:

Household appliances

 

Not only Brushless DC motors are convenient and energy-efficient. But they provide comfort to everyday routine life. Their main use is washing machines, air conditioners, fans, VCDs, DVDs, CDs, vacuum cleaners, and video cameras.

Household Appliances

Industrial Area

 

In the field of manufacturing engineering or automation design, the use of Brushless DC motors is quite common. We use them in motion control,  linear motors, servo motors, and feed drivers.

Auto Industry

 

The auto industry is always evolving. So, we can apply the simple structure, stable speed regulation, and operation of DC brushless motors in the automotive industry.

In the auto industry, we use Brushless DC motors in:

  1. Wipers
  2. Electric doors
  3. Airbags
  4. Electric seats
  5. Automobile air conditioners

Medical Equipment

 

Medical devices should be noise-free. Hence, brushless DC motors provide a wide range of:

  1. Speed regulation 
  2. Low noise
  3. Portability, and other characteristics.

The easy operation and reliability make Brushless DC motors ideal for medical devices.

Is Brushless Motor a Good Replacement of Brushed Motor?

 

You might wonder, Are brushless motors worth the type?

The answer is, it depends. If you are a light-duty user and need to use the tool sometimes, a brushed DC motor might do the job for you. But, if you use your tools often, I recommend upgrading to brushless technology.

I’m sure you will enjoy the perks of a brushless Dc motor considering its functionality and performance.

Whatever it is, set your priorities. If your primary concern is to save the cost, go for DC brushed motors.

Factors to Consider when Choosing the Right Motor for Yourself

 

If you are in a dilemma to choose the right motor for yourself, don’t worry. I will enlist some factors to help you make the right decision.

Except for speed regulation, starting torque or response, power rating, and other technicalities. Consider these factors while choosing the best motor for your application.

Service Life

 

If your field of application requires constant use of the motor, it is vital to check the service life.

Like I mentioned, Brushed DC motors are prone to wear and tear. That’s because of the friction created by brushes and commutators. Thus, it is necessary to determine the service life. If you can afford to maintain your motor, use DC brushed motors.

For example, in toys and other stuff where children are the main users. It is wise to choose DC brushed motors as they are inexpensive.  But, in other practical applications with long life, brushless motors go a long way.

Efficiency

 

Efficiency

Do you know?

Iron-less core brushed DC motors are super-efficient than many brushless motors. But there are cases when they don’t support a particular field of application.

In this case, it is vital to research and examine the efficiency before making a final decision. Usually, brushless DC motors are the real deal when it comes to durability and efficiency.

Control

 

Now, this is where you should scratch your head in confusion.

Brushless motors are super-efficient and convenient. But they cannot beat Brushed DC motors in control and actuation. That is because brushless DC motors need electronic speed controllers. While for brushed DC motors, actuation is easy. Connect the battery across the terminals. And you should be good to go!

Thus, choose Brushless DC motors if the controllers are available. Also, if your field of application is high precision, brushless DC motors are your go-to.

Cost

 

Coming to the last and the most critical factor, i.e., the cost.

The brushless motors use sophisticated components. Thus costly compared to brushed DC motors. Hence, keep in mind the extra costs for other accessories to use BLDC motors before making a final call.

Conclusion

 

The working of brushed and brushless DC motors is the same. But the differences are obvious.

As the name suggests, brushless DC motors are without brushes. Whereas, brushed motors use brushes to deliver the current. 

Yet, brushless DC motors are more energy and power-efficient than their brushed counterparts. Thus, used in a wide range of applications nowadays.

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