基於虛擬磁通無電流感測直接功率控制不平衡電網下三相維也納整流器系統之研製;Development and Implementation of Current-Sensorless Direct Power Control Based on Virtual Flux for Three Phase Vienna Rectifiers under Unbalanced Grids

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Title:	基於虛擬磁通無電流感測直接功率控制不平衡電網下三相維也納整流器系統之研製;Development and Implementation of Current-Sensorless Direct Power Control Based on Virtual Flux for Three Phase Vienna Rectifiers under Unbalanced Grids
Authors:	黃浦沂;Huang, Pu-Yi
Contributors:	電機工程學系
Keywords:	無電流感測控制;虛擬磁通;不平衡電網;直接功率控制;Current Sensorless Control;Virtual Flux;Unbalanced Grid;Direct Power Control
Date:	2025-08-28
Issue Date:	2025-10-17 13:00:11 (UTC+8)
Publisher:	國立中央大學
Abstract:	本論文提出一種針對不平衡電網下三相 Vienna 整流器的無電流感測控制策略，旨在保有系統穩健性下簡化感測器架構。傳統的整流器控制需仰賴交流電流與電壓感測器以實現直接功率控制，然而這不僅增加了硬體成本，更在高頻開關環境下容易受電磁干擾影響，導致控制精度下降。為解決上述問題，本文以虛擬磁通估測為基礎，透過建立輸入交流側模型，結合二階廣義積分器 (SOGI) 與正交訊號產生器 (QSG)，實現對電網電壓及極電壓之虛擬磁通的精準計算，並進一步以虛擬磁通回推輸入電流估測值，取代傳統電流感測器功能。為強化不平衡電網條件下的控制能力，本文將對稱分量法導入虛擬磁通空間，並推導出基於虛擬磁通的瞬時功率與擴充虛功計算。針對此估測架構，本論文設計一套改良型直接功率控制方法，並將虛擬電容補償技術整合到控制中，以抑制不平衡電網所造成的直流側電壓二次漣波。此外，本控制策略引入 PIR 控制器作為功率調節主體，針對二次漣波頻率能做到精確追蹤，進一步提升穩態精度與動態響應。面對 Vienna 整流器在不平衡電網中會產生的電流零交越失真與不可合成問題，本文分析空間向量不可合成區域，且基於電感電流漣波判斷補償的時機。具體而言，透過空間向量對稱性，將Ⅱ-Ⅵ區間的參考電壓向量旋轉等效至Ⅰ區間，使不可合成區之邊界判斷可統一進行，降低即時運算的複雜度。整體控制架構中，不僅能實現無電流感測之功率控制，亦兼具輸出電壓漣波抑制與電流失真補償等功能。 ;This paper proposes a current sensorless control strategy for a three-phase Vienna rectifier operating under unbalanced grid conditions, aiming to simplify the sensing architecture while maintaining system robustness. Traditional rectifier control relies on AC current and voltage sensors to achieve direct power control. However, this not only increases hardware cost but also makes the system more susceptible to electromagnetic interference in high-frequency switching conditions, which can degrade control accuracy. To address these issues, this study adopts a virtual flux estimation approach by establishing an input-side AC model and incorporating a Second-Order Generalized Integrator (SOGI) with a Quadrature Signal Generator (QSG). This allows precise calculation of the virtual flux associated with the grid and pole voltages. The estimated virtual flux is then used to back-calculate the input current, effectively replacing con ventional current sensors. To enhance control performance under unbalanced grid conditions, the symmetrical compo nent method is introduced into the virtual flux space. Based on this framework, instantaneous power and extended reactive power are derived using the estimated virtual flux. A modified direct power control (DPC) scheme is then developed, integrating the virtual capacitor com pensation technique to suppress the second-order voltage ripple on the DC bus caused by grid imbalance. Furthermore, a Proportional-Integral-Resonant (PIR) controller is employed to serve as the power regulator, providing accurate tracking of second-order ripples and improving both steady-state precision and transient response. To address issues such as current zero-crossing distortion and non-synthetic regions that may arise in Vienna rectifiers under unbalanced grid conditions, this paper analyzes the non-syn thetic regions in the space vector domain. A compensation strategy is proposed based on the evaluation of inductor current ripple. Specifically, by leveraging space vector symmetry, refer ence voltage vectors from Ⅱ-Ⅵ sectors are rotationally mapped to Ⅰ region, allowing unified boundary detection of the non-synthetic zones and reducing real-time computational complex ity. The overall control framework achieves current sensorless power control while simultane ously providing DC voltage ripple suppression and compensation for input current distortion.
Appears in Collections:	[Graduate Institute of Electrical Engineering] Electronic Thesis & Dissertation

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