Switched Reluctance Motor Torque Ripple Suppression via Phase Commutation Segmentation
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Solution Overview
Problem
Three-phase switched reluctance motors experience significant torque ripple and limited smooth torque output due to their double salient pole structure and switch-type exciting mode, especially at high rotational speeds and with limited DC supply voltage, making it difficult to control and track expected current, flux linkage, and torque effectively.
Innovation Solution
A three-phase switched reluctance motor torque ripple suppression method is implemented by setting two groups of torque threshold values and controlling the excited states of adjacent phase power supplies, dividing the commutation process into sections to manage torque ripple through specific state transitions and voltage excitations, ensuring smooth torque output across a broader range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional torque control methods are used, then torque ripple can be suppressed in low-speed range, but torque ripple control ability deteriorates at high rotational speeds due to limited DC supply voltage
Solution Approach 1:
The patent divides the commutation process into two distinct sections based on rotor position intervals. In the first section (0° to θ1), phase A uses one set of torque threshold values while phase B uses another set. In the second section (θ1 to θr/3), the threshold value assignment is swapped. This segmentation allows different control strategies to be applied in different operational phases, enabling effective torque ripple suppression across both low and high speed ranges by adapting to the specific electrical characteristics at each rotor position.
Solution Approach 2:
The patent dynamically adjusts the torque threshold values used by each phase based on the rotor position and commutation stage. The control system automatically determines which phase should use which threshold value set (th1low, th1zero, th1up or th2low, th2zero, th2up) depending on the current rotor position interval. This dynamic adaptation enables the system to maintain optimal torque control capability across varying speeds without being constrained by fixed control parameters.
2Reliability
If current is limited by maximum endurable current of winding and volt-ampere rating of semiconductor devices, then device reliability is improved, but torque output smoothness deteriorates due to limited current range
Solution Approach 1:
The patent assigns different torque threshold value sets to different phases based on their local operational characteristics and rotor position. Phase A and phase B use different threshold values (th1 vs th2) depending on which phase is currently being excited and the rotor position interval. This local differentiation allows each phase to operate within its optimal current range while contributing to smooth total torque output, preventing the torque pulsations that would occur if all phases used identical current limits.
Solution Approach 2:
The patent changes the torque threshold parameters (from th1 set to th2 set and vice versa) based on the rotor position and commutation section. By dynamically switching between different threshold value sets, the system expands the effective current utilization range while maintaining device safety limits. This parameter variation enables smooth torque transitions that would be impossible with fixed current limits, achieving both reliability and torque smoothness.
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
This method effectively inhibits torque ripple and achieves smooth torque control by managing phase currents and voltages, allowing the motor to output smooth torque over a maximum range, enhancing universality and application prospects for various three-phase switched reluctance motor drive systems.
Implementation Method 1
its output electromagnetic torque have large pulsation
Implementation Method 2
Switched reluctance motor attracts great attention owing to its simple and firm structure
Data Source
AI summary
A three-phase switched reluctance motor torque ripple three-level suppression method. A first set of torque thresholds (th1.sub.low, th1.sub.zero, th1.sub.up) is set in rotor position interval [0.degree., .theta..sub.r/3]. A second set of torque thresholds (th2.sub.low, th2.sub.zero, th2.sub.up) is set in rotor position interval [.theta..sub.r/3, .theta..sub.r/2]. Power is supplied to adjacent phase A and phase B for excitation. The power supplied for excitation to phase A leads the power supplied for excitation to phase B by .theta..sub.r/3. At this moment, phase A is turned off, phase B is turned on and three-level suppression of torque ripple of three-phase switched reluctance motor is realized by dividing the commutation process from phase A to phase B into two sections.