Brushless DC (BLDC) motors are also known as commutatorless DC motors, electronically commutated motors, AC synchronous motors or DC servo motors. They are increasingly replacing brushed DC motors due to their high efficiency, long life, smooth torque delivery and high speed operation. Their application has been limited in the past due to the additional cost of the complex motor controllers required to operate these motors. Controller costs have been on a downward trend in recent years, so the use of brushless DC motors is increasing and is expected to grow. Although successfully used in the automotive, HVAC, electronics, computer, semiconductor and medical industries, BLDC motors have long been used in industrial applications such as actuators, feed drives for CNC machines, industrial robots, extruder drives, etc.
Although a complex motor controller is required, the simple structure of the BLDC motor provides some inherent advantages that the BLDC motor cannot provide in terms of low energy consumption, high torque and a very wide speed range. BLDC motors use an inside-out configuration. The rotor consists of a series of permanent magnets and a fixed armature. The rotor is excited by an electronic commutation controller. Compared with brushed DC motors, BLDC motors have better heat dissipation and higher efficiency and higher power density.
Due to the absence of brushes and mechanical commutator, its 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), Used to measure the position of the rotor. The feedback signal generated by the encoder is used by the motor controller to generate an input signal to energize the armature current and electronically commutate it so that the armature's magnetic field rotates synchronously with the rotor. The advantages of BLDC motors include:
Longer service life due to lack of electrical and frictional losses. Due to the lack of brushes and mechanical commutator, it is virtually maintenance-free. EMI and noise are reduced due to the elimination of ionization spikes generated by the brushes.
Since they can be completely sealed, they are more suitable for use in hazardous environments (dirt, oil, grease and other foreign matter). Operating characteristics include:
(1) High speed, short index movement;
(2) Heavy load, high torque control;
(3) Short duty cycle motion sum;
(4) High acceleration/deceleration capability.
