4-Phase Switched Reluctance Motor for Torque Ripple and Noise Control
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Solution Overview
Problem
Switched reluctance motors (SRMs) face challenges with severe torque ripples and vibration noise due to intermittent torque generation, making them unsuitable for commercialization, especially at low speeds, and struggle with precise calculation of optimal turn-on leading angles due to variations in instantaneous rotation speed.
Innovation Solution
A 4-phase switched reluctance motor design with two armatures and two rotors, each with equi-angularly arranged salient poles and excitation coils, using sensors for forward and reverse rotation to detect relative positions and adjust turn-on and dwell angles for optimal torque generation, minimizing vibration noise through symmetric electromagnetic and mechanical configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If switched reluctance motor uses intermittent torque generation during inductance increase interval, then simplified electromagnetic structure and high speed operation are achieved, but severe torque ripples and significant vibration noise occur
Solution Approach 1:
The motor is divided into two separate motor units (first and second motor units), each with its own armature and rotor. The armatures are arranged in parallel on the stator, and the rotors are arranged in parallel on the rotor shaft. This segmentation allows each unit to generate torque independently, and when both units operate together, their torque contributions combine to reduce overall torque ripples and vibration noise while maintaining the simplified electromagnetic structure advantage of SRMs.
2Ease of operation
If 2-phase motor unit is used to enable forward/reverse rotation, then continuous torque is achieved at system level, but each motor unit still intermittently generates torque causing vibration
Solution Approach 1:
The control system applies asymmetric control strategies for forward and reverse rotation by calculating different turn-on leading angles (α1 for forward rotation, α2 for reverse rotation) based on the rotation direction. This asymmetric control optimizes torque generation for each rotation direction while maintaining continuous torque output. Additionally, the four excitation coils are controlled asymmetrically during startup to generate maximum torque in the intended rotation direction, preventing reverse rotation and ensuring smooth continuous torque delivery.
3Use of energy by moving object
If turn-on leading angle is calculated based on instantaneous rotation speed, then optimal efficiency is achieved, but precise calculation becomes difficult due to speed variations
Solution Approach 1:
The control system calculates the turn-on leading angle in advance based on the rotation direction before actual operation begins. For forward rotation, a predetermined angle α1 is set; for reverse rotation, a predetermined angle α2 is set. This preliminary determination of optimal angles eliminates the need for real-time calculation during operation, avoiding accuracy issues caused by instantaneous speed variations while still achieving optimal driving efficiency.
4Speed
If maximum torque is generated at startup, then rotation speed stabilization is improved, but vibration noise increases due to asymmetry
Solution Approach 1:
The control system dynamically adjusts the excitation sequence and timing based on the desired rotation direction. During startup, it selectively activates specific excitation coils in a predetermined sequence that generates maximum torque in the intended rotation direction. This dynamic control achieves rapid speed stabilization while the symmetric structure of the dual motor units and balanced coil activation minimizes vibration noise and asymmetry effects.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design enhances high-speed and low-speed efficiency, allows continuous torque generation, reduces vibration noise, and stabilizes rotation speed by optimizing turn-on leading angles, enabling the motor to operate effectively for various purposes with balanced per-phase torques.
Implementation Method 1
two different excitation coils 320 wound thereon, respectively, so that every other one of the armature salient poles 311 is wound with same one of the excitation coils 320
Implementation Method 2
driven with intermittent torque obtained by exciting armature salient poles during an inductance increase interval from the time when a rotator salient pole starts to face an armature salient pole
Implementation Method 3
sensors 340 and 341, as a forward rotation sensor and a reverse rotation sensor, installed at two opposite ends, in a circumferential direction, of each of two armature salient poles 311
Data Source
AI summary
The present invention relates to a 4-phase switched reluctance motor which is configured as a 4-phase motor by coaxially arranging two 2-phase motor units, is capable of effectively driving forward and backward by calculating a switching angle at a time point earlier than the starting point of an inductance increasing period in forward and backward rotations, maximizes the initial driving torque, and minimizes vibration noise by not generating the biased force on a shaft.