DC-AC Converter Harmonic Control via Fourier Analysis
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Solution Overview
Problem
Conventional power conversion systems fail to effectively eliminate harmonics due to reliance on extra hardware, complex calculations, and limited applicability, leading to inefficiencies and increased costs.
Innovation Solution
A power conversion system utilizing Fourier analysis to calculate current harmonics and incorporating a harmonic compensation strategy into the control strategy of a DC-AC power converter, eliminating the need for additional hardware and simplifying calculations, thereby reducing the digital signal processor's load and improving harmonics control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If extra hardware such as passive filters or additional controllers is added to eliminate harmonics, then harmonics suppression effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces physical passive filters (mechanical/electrical components) with a digital signal processing-based active filter that uses microprocessors and algorithms to generate compensation signals, thereby eliminating the need for bulky passive filter components while maintaining harmonics suppression effectiveness
Solution Approach 2:
The system uses the existing voltage and current detection capabilities of the DC-AC power converter control unit to perform harmonics analysis and generate compensation signals, rather than requiring separate dedicated hardware for harmonics suppression
2Measurement precision
If complex calculation methods such as Fourier analysis with multiple conditions are used to compensate harmonics, then harmonics control precision is improved, but calculation load and processing time increase
Solution Approach 1:
The patent extracts only the fundamental wave components and specific harmonic components (5th, 7th, 11th, 13th orders) that are most problematic, rather than analyzing all frequency components, thereby reducing calculation complexity while maintaining effectiveness for the most significant harmonics
Solution Approach 2:
The patent segments the harmonics compensation into different order sequences (positive sequence, negative sequence, zero sequence) and handles them separately through coordinate transformation, making the calculation more systematic and efficient
3Object-generated harmful factors
If additional voltage detection devices and controllers are added to eliminate zero phase sequence harmonics, then harmonics suppression effectiveness is improved, but reliability decreases due to operation uncertainty
Solution Approach 1:
The patent merges the harmonics detection and compensation functions into the existing control unit of the DC-AC power converter, eliminating the need for separate additional controllers and voltage detection devices, thereby reducing points of failure and improving system reliability
Data Source
AI summary
A power conversion system for controlling harmonics, which uses the Fourier transform analysis to calculate the harmonics element of each current, and adds the harmonics compensation strategy into the control strategy of the DC-AC power converter so as to decrease the harmonics element generated from the actual current.