Brushless DC (BLDC) motor, also known as commutatorless DC motor, electronic commutation motor, AC synchronous motor or DC servo motor. Because of its high efficiency, long life, stable torque transmission and high-speed operation, it is increasingly replacing the brush DC motor. Their use has been limited in the past due to the additional cost of complex motor controllers required to operate these motors. In recent years, the cost of controller has been declining, so the application of Brushless DC motor is increasing and is expected to grow. Although BLDC motors have been successfully applied in automotive, HVAC, electronics, computer, semiconductor and medical industries, they have been used in industrial applications for a long time, such as actuators, feed drivers of CNC machines, industrial robots, extruder drivers, etc.

Although complex motor controller is required, BLDC motor has simple structure and provides some inherent advantages that BLDC motor cannot provide in terms of low energy consumption, high torque and very wide speed range. BLDC motor is configured from the inside out. The rotor is composed of a series of permanent magnets and a fixed armature. The rotor is excited by the electronic commutation controller. Compared with the brush DC motor, BLDC motor has better heat dissipation, higher efficiency and higher power density.

Due to the absence of brushes and mechanical commutators, their compact size, reduced weight and high speed range, in order to provide the position feedback required for industrial servo applications, BLDC motors have an encoder (optical or Hall effect) for measuring the position of the rotor. The feedback signal generated by the encoder is used by the motor controller to generate an input signal to excite the armature current and conduct electronic commutation, so as to make the armature magnetic field rotate synchronously with the rotor. The advantages of BLDC motors include:

Longer service life due to lack of electrical and friction losses.

Due to the lack of brushes and mechanical commutators, there is little need for maintenance. The EMI and noise are reduced by eliminating the ionization peak generated by the brush.

Because they can be completely sealed, they are more suitable for hazardous environments (dirt, oil, grease and other foreign matters). Operating characteristics include:

(1) High speed, short index movement; (2) Heavy load, high torque control; (3) Short duty cycle movement and;

(4) High acceleration / deceleration capability.

Reviewed by: Li Qian

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