What is the difference between Switched Reluctance Motor and Synchronous Reluctance Motor?

What is the difference between Switched Reluctance Motor and Synchronous Reluctance Motor

Before discussing the difference between the switched reluctance motor vs synchronous reluctance motor, let’s first understand that both motors are very similar in many things. Both motors are superior to the Induction Motor in efficiency and performance. Both have magnetless as well as copperless rotors. Both switched reluctance motor and synchronous reluctance motor work primarily on the same principle of variable reluctance. Which means rotors made up of ferromagnetic material take position on the minimum reluctance path when stator coils are being energized. Despite so many similarities there is a difference between two motors in operation, design and application.

Comparison of SRM vs SYNRM

Here are some of the differences between the switched reluctance motor vs synchronous reluctance motor which further called SRM and SYNRM:

Working Principle

Stator of the SRM has concentrated windings and each phase produces the salient pole. Whereas, the stator of the SYNRM has a distributed winding like induction motor which produces the rotating magnetic field. 

In the SRM, phase switching is done to change the location of the stator poles with rotor position to produce the rotation of the rotor. In SYNRM, rotating poles are generated due to the rotating magnetic field, and the rotor of the SYNRM rotates with the same speed but slightly lag  behind the rmf with some angle.

SRM required a position sensors to switch the phase energization with rotor position to maintain the continuous rotation. While position sensors are required to maintain the rotor angle to avoid loss of synchronism in SYNRM. 

Switched Reluctance Motor Course

Rotor Design

The switched reluctance motor has a highly segmented rotor (Salient pole) that is made up of magnetic poles and flux concentrators. In contrast,  the synchronous reluctance motor, the rotor has a smooth surface, and it is made up of laminations.

Control Mechanism

The synchronous reluctance motor requires a complex control mechanism, including a feedback sensor, to operate effectively. On the other hand, the switched reluctance motor can operate without a feedback sensor, making it less complex.


The synchronous reluctance motor is highly efficient, which can be designed for an efficiency of up to 98%. In contrast, the switched reluctance motor has a lower efficiency, typically between 80% and 90%.

Power Factor

The synchronous reluctance motor has a high power factor, which is beneficial for the power system. The switched reluctance motor has a low power factor, which may cause power quality issues.

Torque Ripple

The switched reluctance motor has a higher torque ripple compared to the synchronous reluctance motor, making it less suitable for applications where a smooth torque output is required.

Speed Control

The synchronous reluctance motor has better speed control, making it suitable for applications where precise speed control is required. In contrast, the switched reluctance motor has limited but simple and cost effective speed control solutions.


Overall, while both synchronous reluctance motors and switched reluctance motors have their advantages and disadvantages, their differences in working principle, rotor design, control mechanism, efficiency, power factor, torque ripple, and speed control make them suitable for different applications.

In further note, SRM is the oldest electric motor developed in 1838 with mechanical phase switching arrangements. Whereas synchronous reluctance motor is the recent development. The first SYNRM was developed in 1923.

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By Dr. Jignesh Makwana

Dr. Jignesh Makwana, Ph.D., is an Electrical Engineering expert with over 15 years of teaching experience in subjects such as power electronics, electric drives, and control systems. Formerly an associate professor and head of the Electrical Engineering Department at Marwadi University, he now serves as a product design and development consultant for firms specializing in electric drives and power electronics.