Switching Methods in Switched
Reluctance Motors: A Comprehensive
Review
Name:Mohamed Hosam Elsayed Saied
ID:1900439
Sec:5
I. Introduction
SRMs are electric motors that operate based on the principle of
reluctance torque. Unlike traditional motors, SRMs do not have
a permanent magnet, and their rotor consists of salient poles.
The stator windings generate magnetic flux, and by selectively
energizing the windings, the rotor aligns itself with the stator
poles, leading to torque production.
II. Switching Methods
Several switching methods are employed in the control of SRMs to
optimize their performance. The most common methods include:
A. Fixed Switching: This method involves a predetermined fixed
sequence of energizing stator windings. While simple, it may
lead to torque ripple and efficiency issues, especially at low
speeds.
B. Variable Switching: Dynamic adjustments in the switching
sequence can be made based on the rotor position, speed, or
load conditions. This method enhances torque production,
reduces torque ripple, and improves overall efficiency.
C. Pulse Width Modulation (PWM): PWM control involves
adjusting the width of the pulses used to energize the stator
windings. This method allows for precise control of the motor
and minimizes energy losses, resulting in improved efficiency.
D. Hysteresis Control: Hysteresis control maintains the current
within a predetermined hysteresis band. It provides fast
response times and robust performance but may lead to
higher losses.
III.
Advantages of Different Switching Methods
A. Fixed Switching: Simplicity and ease of implementation.
B. Variable Switching: Reduced torque ripple, improved
efficiency, and enhanced dynamic performance.
C. PWM Control: Precise control, reduced energy losses, and
improved efficiency.
D. Hysteresis Control: Fast response times and robust
performance.
IV. Challenges and Considerations
A. Torque Ripple: Managing torque ripple remains a challenge,
especially at low speeds.
B. Complexity: More sophisticated switching methods may
require complex control algorithms and hardware.
C. Switching Losses: PWM control, while reducing energy losses,
may introduce switching losses that need to be carefully
managed.
V. Applications and Future Developments
SRMs are finding applications in various industries, including
automotive, aerospace, and renewable energy. Continued
research is focused on developing advanced control algorithms,
integrated sensor technologies, and materials to further improve
the efficiency and performance of SRMs.