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Everything about Brushless Motors in Details

A brushless motor is an electric motor that runs on direct current (DC) and does not have the mechanical brushes and commutator of a regular brush motor. Although the initial expenditures are greater, it offers obvious benefits over a brush motor and is more cost-effective in the long term. Brushless motors are employed in a variety of trenchless construction applications.

Brushless motors are sometimes known as BLDC or BL motors. Electronically commutated motors (ECMs, EC motors) and synchronous DC motors are synonyms.
Brushless motors are normally built in the same way as permanent magnet synchronous motors (PMSMs), although they can also be switching reluctance motors or induction (asynchronous) motors. They can also be out runners (the stator is encircled by the rotor), in runners (the rotor is enclosed by the stator), or axial runners (the rotor is encompassed by the stator) (the rotor and stator are flat and parallel)


Brushed and Brushless Motors in Time

Since 1856, brushed DC motors have been used for electrical propulsion, cranes, paper machines, and steel rolling mills, and they are still widely used today. Brushless DC motors with electronic speed controller devices have largely replaced brushed motors in many applications since their brushes wear out and need to be replaced often. Due to high application demands and high-electric discharge noise (called ESD, notably in aerospace applications), brush wear became a severe disadvantage, and a new motor was produced.

Brushless motors are much newer, having been conceived at the dawn of electrical invention. The first brushless DC (BLDC) motor, dubbed a “DC machine with solid state commutation” by T.G. Wilson and P.H. Trickey, was invented in 1962 as a result of advances in solid state technology in the early 1960s. Brushless motors are the most preferred choice for computer disk drives, robotics, and airplanes since they do not require a physical commutator.

 brushless and brushed motor
comparison of brushless and brushed motor

Brushless Motors of Modern Day

Early brushless motors had the disadvantage of not being able to generate a lot of power, despite their durability. Brushless motors were able to generate as much (or more) power as brush motors did before stronger permanent magnet materials became available in the 1980s. Robert E. Lordo produced the first large-scale brushless DC motor in the late 1980s, with ten (10) times the power of previous brushless motors.

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Brushless motors today overcome many of the drawbacks of brushed motors by combining higher output power, smaller size and weight, improved heat dissipation and efficiency, wider operating speed ranges, and extremely low electrical noise. Brushless motors feature no electrical connections that might wear out, resulting in greater dependability and shorter maintenance intervals in commercial and industrial applications.

 Brushless Motorscomponents
Brushless motor components

The Essential Aspects and Design of Brushless Motors

The stator of a typical brushless motor has a three-phase winding, while the rotor contains a permanent magnet. It’s also available in single-phase, dual-phase, and three-phase configurations. As previously stated, the stator winding generates a revolving magnetic field that propels the magnetic rotor forward. A three-phase voltage is given to the coil to create this magnetic field.

So, how does the system distinguish between which coils are powered and which should be? A specific electrical controller is employed for this purpose. Current is turned on to orthogonal (perpendicular) windings by such an integrated commutating mechanism. It also has sensors that determine the location of the rotor. Hall sensors are most commonly utilized, however photoelectrical, inductive sensors, and resolvers are also used.

📌 The controller alters the connection of two phases to modify the rotational direction. It can also be used as a servo or stepper motor.

Brushless motor related diagram
Brushless motor diagram

Brushless DC Motors Advantages:

Compared to brushed motors, brushless motors provide a number of benefits:

  • Brushless DC motors have good linear mechanical properties, allowing for a large speed range, stepless speed control, and a wide speed range;
  • Excellent torque characteristics, good middle and low-speed torque characteristics, big beginning torque and low starting current; high overload capacity
  • Soft start and stop, good braking characteristics; original mechanical or electromagnetic brake mechanism can be kept
  • Brushless DC motors have no excitation loss when compared to AC motors, and no brush friction loss and no sparks when compared to brushed DC motors.
  • High dependability, stability, flexibility, and ease of maintenance
  • Compact dimensions, low weight, and great output
  • Bump and vibration resistance, low noise, low vibration, smooth operation, long life

Brushless Motor Disadvantages

As many advantages Brushless motors have there also are a number of drawbacks to them:

  • Cost: Brushless motors have a number of drawbacks, all of which stem from their increased design complexity. To sequence the right charge through the stator coils, BLDCs require a switching controller. This increases the cost of production, which is reflected in the higher starting cost.
  • Complication: Adding complexity increases the risk of failure. We couldn’t locate any research that compared the failure rates of brushed vs. brushless power tools, although it’s often assumed that more complicated equipment is more likely to fail.
cordless tool
cordless tool such as a drill

Brushless Motors Applications

Brushless motors perform many duties that brushed DC motors used to, but cost and control complexity prohibit brushless motors from totally replacing brushed motors in low-cost sectors. Brushless motors, on the other hand, have grown to dominate numerous applications, including computer hard drives and CD/DVD players. Brushless motors are used exclusively to power small cooling fans in electrical devices. They’re common in cordless power tools, where the improved motor efficiency allows for extended durations of usage before the battery has to be recharged. Direct-drive turntables for gramophone records employ low-speed, low-power brushless motors.

Cordless Tools

Many current cordless tools use brushless motors, including string trimmers, leaf blowers, circular and reciprocating saws, and drill/drivers. Brushless motors have more benefits over brushed motors (low weight, high efficiency) for portable, battery-powered equipment than for big, stationary tools plugged into an AC outlet, hence adoption has been faster in that part of the market.

What’s the Best Option, Brushed or Brushless?

Brushless motors, for starters, provide exceptional performance and a long cycle life. These types are required in applications where a fast rotation speed and resistance to overheating are both required. Such equipment is utilized in robots, medical equipment, CNC machines, and other expensive and critical industrial equipment as part of the cooling system. Brushless devices of the same size are more powerful than brushed ones. It’s also employed in situations where long-lasting, low-maintenance electric motors are required.

Brush dc motors have less power and stability than brushed dc motors. It is, however, inexpensive and straightforward. As a result, the gadgets do not do complex or long-term activities. In the home arena, such technology is utilized in autos, hoisting mechanisms, radio-controlled models for children, and various household items (like a drill). Due to brush friction and rapid wear, they require regular maintenance, however they are highly durable in industrial demanding conditions.


FAQ ❓

How do you interpret the numbers on a brushless motor?
Brushless motors are usually identified by a four-digit code, such as , wheredenotes stator width and denotes stator height. Essentially, the greater the numbers and the more torque a motor can create, the broader and taller it is.

What is the number of magnets in a brushless motor?
The printed circuit board’s two coils interact with the fan assembly’s six circular permanent magnets.

How do you determine the size of a brushless motor?
When sizing a brushless DC motor, the easiest place to start is by matching motor size (diameter, length). The diameter spans from 13 to 30 millimeters. The diameter and length of brushless DC slotted motors are measured in inches.

Are cordless tools with brushless motors better?
Brushless motors outperform brushed motors in many ways. Users can benefit from lower maintenance, increased efficiency, and less heat and noise.

What is the life expectancy of brushless motors?
if you want a motor that will last a long time, go with a brushless motor. Brushed motor life is restricted by the brush type and ranges from 1,000 to 3,000 hours on average, but brushless motors may last for tens of thousands of hours.

Conclusion 🧾

The brushless DC motor is a brilliant idea that has revolutionized the electric propulsion industry. They are simple and streamlined in design, allowing vehicles such as RC cars and drones to function with optimum efficiency and control.
We’ve gone over how motors function, the components inside them, and the many types of BLDC motors in this post. We also discussed electromagnetism and how an ESC regulates the motor’s speed. This foundation enables us to comprehend how to maximize efficiency and how needs fluctuate based on the drone’s intended function.-

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Anton Abramov

I am a 29-year-old Russian boy living in Tajikistan. I studied IT at university of Moscow. I have been working with my father's tools since I was a teenager. I fix tools, repair them and I always try to find out how they work. So, I would call myself a geek in power tools. On my journey to becoming a pro, I will try to share the knowledge I've gained through years of experience with you.

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