SRM Torque Ripple Reduction via Current Profile Optimization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Switched reluctance machines (SRMs) face challenges with high electromagnetic torque ripple and acoustic noise due to poor phase current tracking, nonlinear inductance profiles, and non-linear torque-current-rotor position characteristics, which existing control methods struggle to effectively mitigate.
Innovation Solution
A control system for SRMs generates unique current reference profiles based on an objective function and constraint functions, including weight parameters and torque constraints, to optimize phase currents and reduce torque ripple, using equations such as J=ik^2 + σ*ik^-1 and constraints like 0 ≤ ik ≤ irated, and Δλ(i,k)*Δt ≤ VDC - ik*R, to minimize copper losses and improve torque tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional control methods are used for SRMs, then the construction remains simple and low-cost, but high electromagnetic torque ripple and acoustic noise occur
Solution Approach 1:
The patent applies parameter changes by optimizing current reference profiles through an objective function that considers multiple parameters including copper losses, torque ripple, and acoustic noise. The control system dynamically adjusts current magnitudes and timing parameters to minimize harmful effects while maintaining simple SRM construction.
Solution Approach 2:
The patent implements feedback control by using an objective function that continuously evaluates torque ripple and acoustic noise based on actual machine operation. The control system adjusts current reference profiles based on this feedback to minimize harmful effects, creating a closed-loop control mechanism.
2Ease of manufacture
If conventional control methods are used for SRMs, then the construction remains simple and low-cost, but high acoustic noise occurs
Solution Approach 1:
The patent reduces acoustic noise by optimizing current reference profiles through parameter adjustments in the objective function. The control system modifies current magnitudes, switching timing, and phase relationships to minimize acoustic emissions while preserving the simple SRM construction.
Solution Approach 2:
The control system uses feedback from the objective function evaluation to continuously adjust current parameters that influence acoustic noise. This closed-loop approach minimizes noise generation while maintaining the inherent simplicity of SRM construction.
3Power
If phase current is increased to improve torque output, then torque magnitude increases, but copper losses increase
Solution Approach 1:
The patent optimizes the balance between torque output and copper losses by adjusting current reference profiles through the objective function. The control system finds optimal current magnitudes that achieve required torque while minimizing I²R losses in the windings.
Solution Approach 2:
The patent applies partial action by using only the necessary current magnitude required to produce the desired torque, avoiding excessive current that would increase copper losses. The objective function determines the minimum adequate current reference profiles.
4Measurement precision
If switching frequency is increased to improve torque tracking, then torque tracking precision improves, but copper losses and acoustic noise increase
Solution Approach 1:
The patent optimizes switching parameters in the current reference profiles to achieve adequate torque tracking without excessive switching frequency. The objective function balances tracking precision requirements against copper losses and acoustic noise generated by high-frequency switching.
Data Source
AI summary
Various embodiments are described herein for methods and systems for controlling a switched reluctance machine (SRM) having an axially extending rotor mounted to a shaft, an axially extending stator disposed coaxially and concentrically with the rotor, the rotor and stator having a plurality of salient poles, the stator poles protruding radially towards the rotor poles, and a plurality of electrical coils wound about the stator poles including a plurality of separate phase coils defining a plurality of phases of the SRM. In one example embodiment, the method comprises providing a control system operatively coupled to a current controller of the SRM, where the control system is configured to generate a unique set of current reference profiles based on an objective function and at least one constraint function and operating the SRM based on the unique set of current profiles generated by the control system.