BLDC vs DC Motor - Comparison between BLDC Motor and Conventional DC Motor

Comparison between BLDC Motor and Conventional DC Motor:

In this post we will discuss about the Comparison of Permanent Magnet BLDC Motor with DC Motor. Before proceeding further it is highly recommended to read the basics of BLDC motor. Please click here to know about the basics of BLDC motor.

Permanent Magnet BLDC vs DC Motor

PM BLDC MotorConventional DC Motor
It uses electronic commutation based on hall position sensors.It uses brushed commutation.
It requires less maintenance due to the absence of the brushes.It requires periodic maintenance.
It has longer life.It has shorter life.
The speed torque characteristics is flat in nature. So it enables operation at all speeds with rated load.The speed-torque characteristics is moderately flat.
Hence at higher speeds brush friction increases reducing useful torque.
It has higher efficiency.
Hence there is no voltage drop across brushes.
It has moderate efficiency. 
The output power/frame size is higher.
It leads to superior thermal characteristics which results in size reduction. Because BLDC has the windings on the stator, which is connected to the case, the heat dissipation is better.
The output power/frame size is moderate or low.
The heat produced by the armature is dissipated in the airgap, thus increasing the temperature in the airgap and limiting specs on the output power of the frame size.
Rotor inertia is low. Because it has permanent magnets on the rotor.
This improves the dynamic response.
Rotor inertia is higher.
This limits the dynamic characteristic.
The speed range is higher.
Hence no mechanical limitation is imposed by brushes or commutator.
The speed range is lower.
It enables mechanical limitations by the brushes.
It generates low electric noiseArcs in the brushes will generate noise causing EMI in the equipment nearby.
The cost of building higher. Because it has permanent magnets.The cost of building lower.
Motor control is complex and expensive.Motor control is simple and inexpensive
A controller always required to keep the motor running.
The same controller can be used for variable speed control.
No controller is required for fixed speed.
A controller is required only if variable speed is desired.

You may also like to read:
BLDC vs AC Motor – Comparison between BLDC motor with Induction Motor

Squirrel Cage Induction Motor vs Slip Ring Induction Motor
Difference between Electrical Drives: AC and DC Drives
Permanent Magnet DC Motor [PMDC Motor] Tutorial

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2 Responses

  1. meriem says:

    this document is very good, please send me the document of comparision between BLDC motor with induction motor

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