Difference Between BLDC And PMSM Motors, Brushless DC Motor

April 25, 2021November 12, 2022 CS Electrical And Electronics

Hello guys, welcome back to our blog. In this article, we will discuss the difference between BLDC and PMSM motors, brushless dc motors, and permanent magnet synchronous motors.

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Difference Between BLDC And PMSM Motor

Brushless DC Motor (BLDC)

Construction of the BLDC motor says that the Permanent magnet act as a rotating part of the motor called the rotor & stationary part of the motor is made of coil windings called the stator.

BLDCM is working on the Lorentz principle which states that whenever we placed a current-carrying conductor in a magnetic field it experiences a force. Hear current-carrying conductor is the stator’s coil so the PM rotor experiences force and starts rotating. Stator windings in a trapezoidal manner so DC current is required to run the motor.

Hence, the motor will generate trapezoidal back emf & produce torque repulsion. BLDC motor has poor performance because torque and efficiency are affected by torque repulsion. In addition, the BLDC motor is an upgraded version of a brushed DC motor and the absence of brushes gives high speed and increased efficiency.

Permanent Magnet Synchronous Motor

The construction of a PMSM is the same as a BLDCM.

The working principle of PMSM is the same as a synchronous motor, when stator windings are energized rotating magnetic field is produced & emf created rotor is affected by this force and starts rotating at synchronous speed.

The difference is the coil wound over the stator and it is in a sinusoidal manner. So, AC current is required to run the motor. Hence, the motor will generate sinusoidal back emf & produce low torque repulsion.

Due to low torque repulsion, PMSM got higher and smooth torque with higher efficiency and low noise compared to BLDCM. PMSM has a higher power density, which will help in reducing the size of the motor. That’s why PMSM is better than BLDC motors in terms of performance and is good to use in electrical vehicles.

Difference Between BLDC And PMSM Motor

Operation	BLDC Motor	PMSM
Current required	DC	AC
Back EMF wave	Trapezoidal	Sinusoidal
Torque ripple at commutation	Present	Absence
Performance	Poor	Good
Cost	Low	High
Torque and Efficiency	Lower	Higher
Noise	Lower	Lower
Efficiency	85% to 90%	92% to 97%