Switched Reluctance Current Waveform Control for Acoustic Noise
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Solution Overview
Problem
Switched reluctance machines (SRMs) suffer from high acoustic noise and vibration issues, which limit their use in noise-sensitive applications due to the radial forces exciting the motor structure's vibration modes, and there is a need for a method to reduce these noise levels effectively.
Innovation Solution
A system and method to control the current waveform applied to SRMs by determining potential phase current waveforms, evaluating their cumulative sound pressure levels, and identifying a desired waveform that minimizes acoustic noise through iterative optimization, using a look-up table of simulated sound pressure levels based on geometry and pole configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If switched reluctance machines are used due to their simple construction and robustness, then manufacturing cost and reliability are improved, but acoustic noise and vibration increase
Solution Approach 1:
The patent applies parameter changes by optimizing the current waveform parameters (amplitude, duration, switching timing) to minimize acoustic noise. The controller dynamically adjusts current waveform parameters based on operating conditions to reduce noise while maintaining motor performance, directly addressing the contradiction between simple construction and high noise levels.
2Ease of manufacture
If switched reluctance machines are used due to their simple construction and robustness, then manufacturing cost and reliability are improved, but acoustic noise and vibration increase
Solution Approach 1:
The patent optimizes current waveform parameters including amplitude, duration, and switching timing to minimize vibration. By dynamically adjusting these parameters based on operating conditions, the system reduces vibration-induced noise while maintaining the simple and robust SRM construction.
3Productivity
If traditional permanent magnet machines are used to achieve high efficiency and performance, then motor performance is improved, but rare earth metal supply chain risks and environmental impact increase
Solution Approach 1:
The patent extracts the dependency on rare earth permanent magnets by using switched reluctance machines with electronically controlled windings. This eliminates the supply chain risks and environmental concerns associated with rare earth metals while maintaining high motor performance through optimized current control strategies.
4Object-affected harmful factors
If current waveform is optimized to reduce acoustic noise, then acoustic noise level is reduced, but control system complexity increases
Solution Approach 1:
The patent replaces complex mechanical noise reduction structures with electronic control of current waveforms. The controller uses software-based optimization algorithms to minimize acoustic noise, avoiding the need for additional mechanical components or complex physical modifications to the motor structure.
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 approach effectively reduces acoustic noise in SRMs by directly controlling the current waveform, considering both electrical and mechanical aspects, allowing for wider application in noise-sensitive environments without the need for vibration sensors.
Implementation Method 1
Switched reluctance machines operate using electrical coils that are selectively energized to induce magnetic flux and compel the rotor of the switched reluctance machine to rotate.
Implementation Method 2
SRMs can have high acoustic noise and vibration, which can impede the use of SRMs in noise-sensitive applications
Implementation Method 3
radial forces exciting the motor structure's vibration modes
Data Source
AI summary
The current profile of excitation current provided to the electrical coils of a switched reluctance machine is controlled to reduce acoustic noise. A plurality of potential current waveforms can be evaluated to select a desired waveform that reduces the acoustic noise level of the switched reluctance machine. A cumulative sound pressure level of the switched reluctance machine can be determined for each potential current waveform. The cumulative sound pressure level can be determined based on a plurality of harmonic sound pressure levels expected to result from the potential current waveform. A desired current waveform can be identified as the potential current waveform associated with an optimal cumulative sound pressure level. The desired current waveform can then be applied to the corresponding phase coil of the switched reluctance machine in order to operate the switched reluctance machine while reducing acoustic noise without sacrificing other motor performance metrics.