Switched Reluctance Motor Torque Ripple Reduction via Online TSF
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Solution Overview
Problem
Conventional switched reluctance motors suffer from torque pulsations, acoustic noise, and vibration issues due to inherent torque ripples, which limit their torque-speed performance and efficiency.
Innovation Solution
A torque control system is introduced that detects torque errors between the overall torque reference and response, compensating by adjusting the torque references of phases with lower maximum absolute rate of change of flux linkage, operating in two modes to optimize phase tracking during commutation, using a proportional and integral compensator and feed-forward systems to generate compensation torque references.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional switched reluctance motor operation is used, then extended constant power speed range and four-quadrant operation are achieved, but torque pulsations, acoustic noise and vibration occur due to inherent torque ripples
Solution Approach 1:
The patent implements a feedback control mechanism where the actual torque is measured and compared with the reference torque, and the error signal is used to adjust the torque references of individual phases. This closed-loop feedback system continuously compensates for torque ripples, reducing the harmful torque pulsations while maintaining the motor's four-quadrant operation capability.
Solution Approach 2:
The patent dynamically changes the torque reference parameters of individual phases based on the detected torque error. By adjusting the torque references in real-time according to the operating conditions and error signals, the system optimizes torque production while minimizing torque ripples across the extended speed range.
2Object-generated harmful factors
If torque control is implemented to reduce torque ripples, then torque pulsations are reduced, but control system complexity increases
Solution Approach 1:
The patent segments the overall torque control into individual phase torque controls. Instead of controlling the motor as a single unit, the system divides the torque production into separate controllable phases, allowing independent adjustment of each phase's torque reference to compensate for ripple effects while maintaining manageable control complexity.
Solution Approach 2:
The patent introduces a torque compensation mechanism as an intermediary between the reference torque command and the actual torque output. This intermediary compensation system processes the torque error signal and generates corrective torque references, acting as a mediator that reduces torque pulsations without requiring complete redesign of the entire control system.
3Reliability
If phase torque references are adjusted for compensation, then torque error is reduced, but copper losses may increase due to higher RMS currents
Solution Approach 1:
The patent employs dynamic torque reference adjustment where the compensation torque references are continuously adapted based on the detected torque error and operating conditions. This dynamic approach allows the system to optimize torque production in real-time, achieving accurate torque tracking while minimizing excessive current draw and associated copper losses through adaptive control.
Solution Approach 2:
The patent applies partial compensation by adjusting only the necessary phase torque references to eliminate torque errors, rather than uniformly increasing all phase currents. This selective partial action achieves the required torque tracking accuracy without unnecessarily increasing RMS currents and copper losses across all phases.
Data Source
AI summary
Various embodiments are described herein for an extended-speed low-ripple torque control of a switched reluctance motor (SRM) using online torque sharing function (TSF). Two operational modes of an online TSF are defined during the commutation: In Mode I, absolute value of rate of change of flux linkage (ARCFL) of incoming phase is higher than outgoing phase; in Mode II, ARCFL of outgoing phase is higher than incoming phase. To compensate the torque error produced by imperfect tracking of phase current, a proportional and integral compensator with torque error is added to the torque reference of outgoing phase in Mode I and incoming phase in Mode II. Therefore, the total torque is determined by the phase with lower ARCFL rather than the phase with higher ARCFL as in conventional TSFs.