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.
Advantages of Brushless DC Motors
The benefits of Brushless DC (BLDC) motors are the following:
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. BLDC motors use permanent magnets and an electronically controlled commutation system to achieve high efficiency and power density. The absence of brushes and losses in the rotor means that BLDC motors can be smaller in size and weight for equivalent power output making them suitable for a wide range of applications, including electric vehicles, drones and industrial machinery.
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. BLDC motors do not have brushes and instead use electronic commutation to control the motor. This eliminates the need for brush maintenance and reduces the risk of mechanical failure.
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. This is because brushed motors use a commutator which is a mechanical switch that directs current to the different windings of the motor. As the commutator rotates, it creates sparks that generate electromagnetic interference (EMI) and RF noise.
In contrast, brushless motors use electronic speed controllers (ESCs) to control the flow of current to the motor windings. The ESCs operate at high frequencies which helps to filter out any EMI or RF noise generated by the motor.
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 so much added cost.
11. Better heat removal
BLDC (Brushless DC) motors generally have better heat removal compared to traditional brushed DC motors because of their more efficient design.
One reason for this is that BLDC motors have a lower resistance, which means that less electrical energy is converted into heat. Additionally, BLDC motors have a more compact design with a higher power-to-weight ratio which allows for better heat dissipation.
12. Noiseless operation
Consumers now demand reduced acoustic noise. Traditional technologies cannot provide the solutions but BLDC motors can operate silently. However, it’s important to note that the level of noise reduction achieved with BLDC motors depends on various factors such as the design of the motor and the application in which it is used.
In conclusion, brushless DC motors (BLDC) have revolutionized motor technology due to their several advantages over traditional motor technologies. These benefits include compact size, high efficiency, high speed, low maintenance, fast response, lower radio frequency interference, linear speed-torque characteristics, high starting torque, adjustable speed, better heat removal and noiseless operation. These features make them ideal for a wide range of applications such as electric vehicles, drones and industrial machinery. As technology continues to improve, it’s expected that the efficiency and power density of BLDC motors will only increase making them even more prevalent in the future.