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Comparison between brushless motor and brushless motor

Classification:Common Problem Release time:2022-10-26 99

In the brushless DC motor, the electronic servo system replaces the mechanical commutator contact. The electronic sensor detects the angle of the rotor and controls semiconductor switches, such as transistor switches and current flow through the coil. The sliding contact is eliminated, so that the brushless motor has less friction and longer service life. Their service life is only limited by the bearing life.


Brushless DC motor produces large torque at standstill, which decreases linearly with the increase of speed.


Brushless motors can overcome some limitations of brushless motors, including higher efficiency and lower sensitivity to mechanical wear.


A typical brushless motor has a permanent magnet that rotates around a fixed armature, eliminating the problem of connecting current to a moving armature. An electronic controller replaces the brushless DC motor of the brush/commutator assembly. It continuously switches the phase winding to keep the motor running. The controller performs similar timing power distribution by using a solid-state circuit instead of a brush/commutator system.


Compared with the brushless DC motor, the brushless DC motor has several advantages, including high torque-to-weight ratio, greater torque per watt (improving efficiency), higher reliability, lower noise, longer service life, elimination of ionizing sparks generated by the commutator, and overall reduction of electro-magnetic interference. Since there is no winding on the rotor, they are not subject to centrifugal force, and because the winding is supported by the shell, they can be cooled by conduction without the need for air flow inside the motor.


Brushless motor commutation can be realized in software using microcontroller or microprocessor computer, in analog hardware, or in digital firmware using field programmable gate array (FPGA). Using electronic devices to replace the brush for commutation can achieve greater flexibility and function, which is not provided by the brush DC motor, including speed limit, "micro step" operation for slow or fine motion control, and holding torque at rest. The controller software can customize specific motors for use in applications, resulting in greater commutation efficiency.


The high power applied to brushless motor is largely limited by heat. Excessive heat will weaken the magnet and damage the insulation performance of the winding. When converting electric power into mechanical power, brushless motor is more efficient than brushless motor. This improvement is largely due to the frequency of switching current determined by the position sensor feedback. In the no-load and low-load areas of the motor performance curve, the efficiency is greatly improved. Under high mechanical load, the efficiency of brushless motor and high-quality brushless motor is equivalent.