EMI Mitigation via Switching Angle Modulation
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Solution Overview
Problem
Existing power electronics systems face challenges in reducing electromagnetic interference (EMI) noise due to high frequency harmonics, which degrade system reliability and increase costs with bulky hardware solutions, while software/modulation techniques have limitations in effectiveness and complexity.
Innovation Solution
A software/modulation technique that adjusts switching angles to disperse EMI energy into non-EMI frequency ranges, reducing total harmonic energy and noise without adding passive components, utilizing a modulation block to control duty cycles and DC voltage levels, and employing genetic algorithms for optimal switching angle determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If hardware solutions (passive components like filters and inductors) are added to reduce EMI noise, then EMI noise reduction is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces hardware-based EMI filtering (mechanical/electrical system) with a software/modulation-based approach. By using optimized switching sequences and pulse width modulation techniques, the system achieves EMI reduction without adding passive components like inductors, capacitors, or filters, thus eliminating the need for bulky hardware while maintaining noise reduction effectiveness
Solution Approach 2:
The patent changes the switching parameters (timing, duration, sequence) of power electronic devices to control harmonic generation. By adjusting switching angles, duty cycles, and modulation indices, the system redistributes harmonic energy across different frequencies, pushing EMI energy out of problematic frequency ranges without requiring additional hardware components
2Object-affected harmful factors
If hardware solutions (passive components) are added to reduce EMI noise, then EMI noise reduction is improved, but cost increases
Solution Approach 1:
The patent replaces expensive passive components (inductors, capacitors, EMI filters) with software-based control algorithms. This substitution eliminates material costs associated with bulky hardware while reducing assembly and maintenance costs, making the system more cost-effective despite requiring sophisticated control software
Solution Approach 2:
The patent uses computational resources (software algorithms running on existing controllers) instead of expensive, long-lived passive components. The 'cost' is incurred in terms of processing power and algorithm complexity rather than physical materials, which can be updated or modified without hardware replacement
3Device complexity
If software/modulation techniques are used to reduce EMI noise, then device complexity is reduced, but effectiveness is limited
Solution Approach 1:
The patent employs dynamic switching strategies where modulation parameters (switching angles, duty cycles, pulse widths) are continuously adjusted based on operating conditions. This dynamic approach allows the system to adaptively optimize EMI reduction across different load conditions and frequency ranges, overcoming the limitations of static software techniques
Solution Approach 2:
The patent divides the switching cycle into multiple segments with different modulation strategies. By applying different switching sequences and pulse patterns to different time segments or phases, the system can target specific harmonic frequencies and distribute EMI energy more effectively across the spectrum, enhancing overall reduction effectiveness
4Productivity
If switching frequency is increased to improve device performance, then productivity is improved, but EMI noise increases
Solution Approach 1:
The patent uses periodic pulse width modulation where switching occurs at optimized intervals rather than continuous high-frequency switching. By carefully timing the periodic switching actions and using complementary switching sequences, the system achieves the necessary power conversion performance while creating notches or reductions in the frequency spectrum where EMI is most problematic
Data Source
AI summary
Various examples related to electromagnetic interference (EMI) energy mitigation techniques are provided. In one example, a method includes adjusting switching angles of a switching circuit based on resolution bandwidths (RBWs) associated with an EMI frequency spectrum of the switching circuit and weight coefficients of the RBWs. The total energy of the switching circuit can be reduced by adjusting an average duty cycle of the switching circuit. EMI spectrum information can be determined based upon switching angles of a switching circuit. For example, weighted errors corresponding to differences between reference harmonic magnitudes and determined harmonic magnitudes can be determined. In response to a comparison of a maximum weighted error to a preset tolerance threshold, adjustment to the switching angles can be determined and/or applied.