Converter Resonance Control With Differentiated Phase Correction
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Solution Overview
Problem
Conventional resonance control methods for three-phase high power converters with low carrier wave ratios face limitations in stability margin and dynamic performance due to asymmetrical positive and negative bilateral frequency domains, which are not adequately addressed by single-phase correction approaches.
Innovation Solution
A resonance control method that performs differentiated phase correction using a complex vector transformation and decoupling control, allowing for independent phase correction angles at positive and negative resonance poles, enhancing the system's stability and dynamic performance by combining resonance and decoupling control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If equivalent phase correction with single phase correction positive degree of freedom is adopted, then the control scheme is simple, but it cannot meet the differentiated phase correction demand of positive and negative resonance poles simultaneously, limiting the improvement of stability margin
Solution Approach 1:
The patent segments the phase correction function into two independent parts: one for positive resonance pole (θ1) and one for negative resonance pole (θ2). This allows each resonance pole to have its own optimized phase correction angle, addressing the asymmetrical characteristics of positive and negative frequency domains separately rather than using a single unified correction angle.
Solution Approach 2:
The patent applies local quality by assigning different phase correction angles (θ1 for positive, θ2 for negative) to different frequency domains. This enables each part of the frequency spectrum to receive customized phase correction tailored to its specific characteristics, improving overall system stability without compromising either frequency domain.
2Device complexity
If conventional PI control under synchronous coordinate system is used, then the control structure is simple with single resonance pole, but the suppression capability and dynamic performance to negative-sequence current are insufficient
Solution Approach 1:
The patent merges two resonance control schemes into one unified controller: the positive sequence resonance control (for positive frequency domain) and negative sequence resonance control (for negative frequency domain). This combination enables the system to simultaneously suppress both positive and negative sequence currents while maintaining simple control structure through unified implementation.
Solution Approach 2:
The patent introduces asymmetry by using different resonance coefficients (Ki1 for negative resonance, Ki2 for positive resonance) and different phase correction angles (θ1, θ2) for positive and negative frequency domains. This asymmetric design matches the inherent asymmetry in power system frequency domains, enabling optimized suppression of negative-sequence current while maintaining overall system balance.
3Device complexity
If low carrier wave ratio working condition is adopted, then the converter is compact and cost-effective, but the stability margin of control link is insufficient and dynamic performance is degraded
Solution Approach 1:
The patent changes the control parameters by introducing differentiated phase correction angles (θ1, θ2) and separate resonance coefficients (Ki1, Ki2) specifically optimized for low carrier wave ratio conditions. These parameter adjustments compensate for the reduced stability margin inherent in low carrier wave ratio operation, enabling the converter to maintain good dynamic performance with compact configuration.
Data Source
AI summary
A resonance control method for differentiated phase correction under asymmetric positive and negative bilateral frequency domains includes a differentiated phase correction resonance control link with an independent phase correction angle at each resonance point, a decoupling link and a delay compensation link. As a high power converter has the characteristic of asymmetric positive and negative bilateral frequency domains under resonance control with decoupling, stability margin of a control link is enhanced while a negative-sequence current suppression capability is realized by means of differentiated phase correction at positive and negative resonance poles.