高功率三相三線式雙向換流器研製

Design and Implementation of High Power Three-Phase Three-Wire Bi-directional Inverter

陳盈修(Chen, Ying Hsiu)

指導教授 ： 吳財福

國立清華大學/電機資訊學院/電機工程學系/碩士(2015年)

摘要

本研究研製一部三相三線式雙向換流器，其功能包含市電併聯及整流功能，電路分為電力級與控制級兩部份，在市電併聯模式中，將直流電轉換成交流電饋入市電電網；在整流模式中，將市電轉換成直流電供給直流負載。電力級之電路採用三相三線式全橋架構，控制級使用微控制器Renesas RX62T來實現本研究所採用之分切合整數位控制法，其優點為不必受限於傳統控制法所採用的abc至d-q座標轉換，且克服電感值隨電流增大而衰減之問題，並有效降低鐵芯尺寸及適用於三相電壓失真含有諧波之情況。本文首先對換流器進行建模，接著基於分切合整數位控制的精神，透過抵消系統參數如直流鏈電壓、切換週期及電感變化對受控體的影響，來得到開關責任比率的控制法則，並以向量調變之方式來推導基於兩相調變之下的開關責任比率公式，且說明系統之穩壓機制以及電感鐵芯規格與材質之選擇。最後實作一部單相三線式雙向換流器，並經由實測結果驗證本研究所提出之理論與換流器操作之可行性。
本研究主要有兩項貢獻：第一為推導開關責任比率控制法則的過程與文獻中關於分切合整數位控制的推導不同，本論文在推導過程中遵循傳統控制系統的程序，首先對系統建模，接著設計其控制器進而得到開關責任比率公式，最後得出整個系統的控制方塊圖並且分析其穩定度。第二為將分切合整數位控制應用於高功率系統，並且改善元件之非理想特性所造成的影響。

關鍵字

分切合整數位控制 ； 兩相調變 ； 寬廣感值變化 ； 雙向換流器 ； 高功率

並列摘要

This thesis presents design and implementation of a three-phase three-wire bi-directional inverter with two operation modes, grid-connection mode and rectification mode. In grid-connection mode, the power is transformed into AC and injected into the utility grid. In rectification mode, power from the utility grid is transformed into DC to supply DC loads. The circuit is divided into two parts, including a power stage with the configuration of a three-phase three-wire full-bridge inverter and a control stage with a single-chip micro-controller Renesas RX-62T implementing the control law of Division-Summation (D-Σ) Digital Control. With the proposed control method, the limitations of abc to d-q frame transformation can be overcome and the core size can be reduced significantly, since inductance variation is taken into account. Additionally, the proposed control method can accommodate the effect of three-phase voltage distortion and imbalance. First, plant derivation based on D-Σ digital control is discussed. Next, the controller is derived with the aim of canceling the variation effects of dc voltage, switching period and inductances. Then, the derivation of duty ratios based on Two-Phase Modulation with the reallocation of T0 and T7 is explained in detail. In addition, the mechanism of DC-bus voltage regulation and selection of the inductor core are also presented. Finally, the inverter has been implemented and tested. Simulated and experimental results have verified the feasibility of the proposed control scheme.
There are two major contributions in this research. First, the derivation of duty-ratios is different from that in the literature related to D-Σ digital control. In this research, the derivation follows the procedure of the conventional control system theory in which the plant is derived first, and then the controller is designed. Finally, a system control block diagram is obtained and stability is analyzed. Secondly, the D-Σ digital control is applied to a 60 kW power converter system and the effects caused by nonideal characteristics of the components are considered and improved.

參考文獻

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