Brushless (BLDC) motors are an indispensable part of modern drive technology, most commonly employed for actuating drives, machine tools, electric propulsion, robotics, computer peripherals, and also for electrical power generation. With the development of sensorless technology besides digital control, these motors have become very effective in terms of total system cost, size, and reliability. Brushless DC motors have several advantages over competing motor technologies. The following list summarizes these advantages and the underlying reasons.
The benefits of brushless DC motors are the following:
1. Unique working principle
The brushless units rely on their commutation through the use of a shaft position sensor sending a signal to an external winding switching circuit. Brushless DC motors can be studied in three main parts which are stator, rotor, and electronic commutator. The rotor is the rotating part of the motor; its magnetic field is provided by permanent magnets generally. The stator is the stationary part of the motor; its magnetic field is produced via copper wires in slots. The electronic commutator determines the sequence of driving currents through the stator wires in a brushless DC motor, replacing the function of brushes in conventional motors.
2. Compact size
Modern permanent magnets and no losses in the rotor enable the brushless DC motor to be smaller compared to both brush DC motors and induction AC motors.
3. High efficiency
A permanent magnet in the rotor. Unlike AC induction motors, there are no core losses in the rotor. BLDC motors are reliable and energy-efficient, and their technology has been continuously improved since their invention. The development of BLDC motors and drivers depends on other technologies, such as microelectronics and driver algorithms. New microelectronic components and algorithms are being created continuously, and with the help of these improvements, the efficiency of BLDC motors increases.
4. High speed
No brushes to limit speed, lower speed losses by design. BLDC motors have been designed for speeds as high as 100,000 RPM. The problem of retention of magnets, in a rotor spinning at high speeds, has long been solved.
5. No maintenance
BLDC motors have no brushes to replace, inspect or maintain. Brushless motors require less maintenance, so they have a longer life compared with brushed DC motors.
6. Fast response
Compared to induction machines the BLDC motor has lower inertia, allowing for a faster dynamic response to reference commands. Moreover, advancements in power electronic devices and DSP/FPGA-based processors have added more features to these motor drives to make them more prevalent in industrial installations.
7. Lower radio frequency interference
Typically, brushed motors generate more RF interference than their brushless counterparts.
8. Linear speed-torque characteristics
Internal shaft position feedback. Permanent magnet design with internal shaft position feedback gives BLDC motors linear speed-torque characteristics when compared to “open-loop” AC induction motors.
9. High starting torque
Internal shaft position feedback gives BLDC motors higher starting and low-speed torque when compared to “open-loop” AC induction motors.
10. Adjustable speed
The commutation electronics of BLDC motors can be used for speed control without added cost.
11. Better heat removal
The heat-generating element is the stator which is on the outside of the motor as opposed to being on the inside as in the case of a brush DC motor.
12. Much better controllability versus induction motors
Linear speed-torque characteristics due to internal shaft position feedback and permanent magnet design.
13. Noiseless operation
Consumers now demand reduced acoustic noise. Traditional technologies cannot provide the solutions but BLDC motors can operate silently.