Tag Archive for: BLDC Motor

Brushed v brushless motor

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When designing compact motor drive programme , the first choice user makes is between brushed and brushless dc motors.

Undoubtedly, both types of motors have advantages and disadvantages, but which type is more suitable for specific applications? It requires analysis of characteristics of both type.

First, service life

The mechanical reversing system of the brushed motor directly affects its service life. The reversing system is directly affected by the load condition. The large current, high speed, reverse motion and high strength vibration generated during operation will reduce its service life.

Brushed motor

The brushless motor used an electronic reversing design instead of a mechanical reversing design, which greatly prolongs motor life and reduces maintenance. Moreover, the life of the motor can be predicted relatively accurately. For example, ball bearing will limit the service life of the motor, and the service life of the motor can be accurately inferred through the design life of the bearing.

Brushless motor

Secondly, motor speed

Because of reversing system, the speed of brushed motor is generally less than 10,000 rpm. In over speed operation, the service life of the motor will be greatly shortened due to the increase of electrical and mechanical wear.

Brushless motors of the same size and magnetic structure can operate at higher speeds, even more than 100,000 rpm.

Thirdly, use environmental conditions

Brush reversing systems may generate sparks that can cause electromagnetic interference. Graphite dust from brushes can contaminate clean rooms, vacuum or optical applications.

At last,Motor control and operation

Brush motor is easy to operate, as long as the voltage is enough, the motor can start to work.

While BLDC motor requires additional electronic reversing control equipment and more complex wiring. But in applications which precise control is needed, the cost and wiring is the same for both types. With BGM’s brushless motor kits, the wiring can be done in 1 second, and speed can be adjusted by the knob easily. What’s more, the price of this bldc motor kits is low, as we cut down reductant function to save cost.

To sum up,

BLDC motor is more adaptable to different environmental conditions. It has longer service life , and has advantages on high speed applications.

 In simple drive applications, the wiring and cost of brushed motors are more dominant, and the two are similar in precise control situations.

Of course, the final choice also needs to be considered in all aspects according to the specific application scenario.

57mm bldc motor

What are differences between BLDC motor and AC motor

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The brushless motor system consists of a motor and a brushless motor controller.  Since the BLDC motor runs in a self-controlled manner, it has no additional starting winding to the rotor as the asynchronous motor. Even if the load changes suddenly, there will be no oscillation or out-of-step.

sh kitsAC motor is a device that converts AC electric energy to mechanical energy. It mainly comprises electromagnet winding or distributed stator winding and a rotating armature or rotor.  There are synchronous AC motor and AC induction motor.

Compared with AC motors, the brushless motor has the following advantages:

  1. High torque at low speed. At low speeds, the torque of the AC motor is low, while the torque of the BLDC motor is much higher.
    bldc high torque at low speed
  2. Wide speed range. Generally, the speed range of the BLDC motor is 50-3000RPM, AC motor is 150-1350RPM. Moreover, the BLDC motor speed could be adjusted evenly and smoothly even under heavy load.
  3. High efficiency. The efficiency of the brushless motor is more than 75%, while the efficiency of the AC motor is only 30~40%. Therefore, brushless motor is more energy-saving, which is in line with the global trend of energy conservation and environmental protection
  4. Quick response. Similar to car starting, a car with superior performance accelerates quickly, and so does a brushless motor.
  5. Compact structure. At the same power, brushless motors are smaller than AC motors, so they require less raw materials and save more cost.
  6. DC or AC power input. If the BLDC motor driver is connected to AC, the driver converts AC to DC for the motor to work. If DC is input, the drive does not need to convert. Compared with AC, DC has the advantages of convenience and safety. For example, for AGV equipment, high torque brushless motor is widely used as it can be input DC. Because it’s safer, a brushless DC motor is often used for entertainment equipment.

Generally speaking, the selection of motors is based on all aspects of specific applications. Users are increasingly leaning towards DC motors, especially BLDC motors.