What is the difference between PMDC, BLDC, and PMSM motor

aarohi manager Apr 17, 2021 Difference between BLDC and PMDC motor 0 Comment

Brushless DC machines ( BLDC), Permanent Magnet Synchronous Machines (PMSM), Permanent magnet dc motor (PMDC) usage is ubiquitous.

There is a lot of common knowledge on these technologies. PMDC are ideally suited for automobiles starter, toys, BLDC machines are the most obvious candidate for high-speed applications, etc. ,PMSM Motor ideally suitable for application like robotics, machine tools etc.

A quantitative comparison between motor technologies can add useful information to the common knowledge on choosing an optimal motor technology.

Difference between PMDC, BLDC, and PMSM motor

Sr. No	PARTICULAR	PMDC	BLDC	PMSM
Construction
1	Rotor	Winding on rotor/armature	Permanent magnet On rotor	Permanent magnet On rotor
2	Stator	Permanent magnet on stator	Windings on the stator	Stator with a Coil wound over it
3	Controller	No Controller require	Controller is Required	Controller is Required
Features /Performance
5	Torque	Suitable for low torque application	Suitable for High torque application	High torque Compared to BLDC
6	Speed	Lower speed range due to mechanical imitation of brushes	Higher speed range due to no mechanical limitation imposed by brushes/ Commutator	Higher speed range and efficiency
7	Life	Typical life expectancy is 2000-5000 hours depending on application and duty cycle	Typical life expectancy 10000, to 20,000 hours	Typical life expectancy 10000, to 20,000 hours.
8	Efficiency	Typically 60-70%	High Efficiency up to 90%	High Efficiency up to 92%
9	Commutation method	Uses mechanical commentator to reverse polarity of the armature electromagnet	1)Sinusoidal Drive with FOC. 2)Trapezoidal with Back EMF Sensing	1)Sinusoidal Drive with FOC. 2)Trapezoidal with Back EMF Sensing
10	Rotor Position Detection	NA	1) With Sensor 2) Sensor less	1) With Sensor 2) Sensor less
Benefits/Comparison
11	Maintenance	Periodic maintenance require, can replace brushes for extended life if necessary	Little to no maintenance	Little to no maintenance
12	Heat Dissipation	Internal rotor Construction result in Limited heat dissipation	Superior thermal characteristic result in better heat dissipation	Efficient dissipation of heat
13	Noise	Brushes emit audible noise during rotation	Low electric noise generation	Low electric noise generation
14	Cost	Lower manufacturing cost	Higher manufacturing cost	Higher manufacturing cost
15	Operation Environment	Can operate in more extreme environment due to lack of electronics.	More suitable for normal controlled environments	More suitable for normal controlled environments
16	Application	automobiles starter, toys, wipers, washers, hot blowers, air conditioners, computer disc drives and in many more.	linear motors, servomotors, actuators for industrial robots, extruder drive motors and feed drives for CNC machine tools. etc.	robotics, machine tools, actuators, and it is being considered in high-power applications such as industrial drives and vehicular propulsion.

Conclusion:

It is a common misassumption that a Brushed DC machine is the cheapest option. However, this machine is still interesting due to its high overload capacity.

BLDC machines are especially interesting for high speed applications and applications where a continuous rotation is needed. Using them to position would be cost inefficient but eventually justifiable based on its high dynamic performance.

PMSM machines are known to be the most expensive option but as the minimal configuration already requires position feedback they are ideally suited for accurate positioning.

Reference : Research paper on A quantitative comparison between BLDC, PMSM, Brushed DC and Stepping Motor Technologies