數位信號處理器控制之脈寬調變換流器輸出電壓正弦合成方法之研究

Abstract

中文摘要 本論文針對脈寬調變換流器輸出電壓正弦合成方法進行研究，文中提出三 種應用於正弦電壓合成之數位控制架構：具有增益調適機制之最佳狀態回 授控制、具有積分補償之最佳狀態回授控制及具有前饋補償之數位式順滑 模態控制，前二者屬於線性控制技術而後者則屬於非線性控制技術。本文 所提出的數位控制器都是直接在離散領域進行設計與實現，而非以類比方 式設計再經由離散等效(discrete equivalent) 方法轉換實現。本論文由 脈寬調變換流器之離散數學模型出發，以量測數據驗證模型之精確度、建 立電腦輔助設計與模擬環境、研究應用於正弦電壓合成之線性與非線性數 位控制架構、進行穩定性及負載干擾影 響分 析、以電腦模擬驗證理論之可行性、完成以數位信號處理器為基礎之全數 位式脈寬調 變換流器控制系統之研製，本論文詳細說明全數位式脈 寬調變換流器交流穩壓控制系統之分析與設計。本論文所提出的狀態回授 控制器具有架構簡單、設計方法明確的優點，非常適合電腦輔助設計流程 。文中提出增益調適(gain scheduling) 與積分補償機制以改善狀態回授 架構於負載變動下之穩健性。論文中引入量化觀念，使設計者得以依據時 域響應規格進行量化設計。此外，本論文首次將數位式順滑模態控制理論 應用於脈寬調變換流器之正弦輸出電壓合成。文中所提出的數位式順滑模 態控制架構僅須透過輸出電壓回授即可達成閉迴路控制，大幅降低生產成 本。順滑模態控制器之順滑平面(sliding surface) 是透過最佳控制理論 進行設計，在特定狀況下能使系統具有最佳的動態響應。最後，本文以 PC-DSPLab 交談式數位控制器發展系統為基礎，建構一套脈寬調變換流器 之數位控制系統進行實驗測試。實驗結果與電腦模擬互相吻合，證明控制 架構的有效性與理論分析的正確性。 Abstract The fully digital control of the PWM inverterfor sinusoidal output waveform synthesis has been examined inthis dissertation. The discrete model of the PWM inverter concerned has been derived. The uncertainties and constraints imposedon the controlled inverter has also been described. Three control schemes areproposed for the closed-loop regulation of the PWM inverter: optimal statefeedback scheme with gain scheduling mechanism, optimal state feedback schemewith integral compensation, and discrete sliding mode control scheme with feedforward compensation. The first two are essentially linear design strategies, while the last one is nonlinear by nature. The two optimal state feedback schemes proposed in this dissertation are simple in architecture. The optimal feedback gains are searched by the method of steepest descent such that the output response is optimal subject to the selected cost function. A gain scheduling mechanism is proposed to deal with the uncertainty caused by load variation. In addition, we also propose an integral compensation scheme toimprove the tracking performance of the controlled PWM inverter. The whole design process including searching optimal feedback gains, checking stability margin, examining time response has been computerized. The discrete sliding mode control scheme proposed in this dissertation is essentially a state feedback scheme with variable gains. The gains are designed such that thecontrolled system can match the reference dynamics which is governed by the sliding surface. In the proposed control scheme, a feedforward compensator is added to improve the tracking performance as well as lessen the burden of thesliding mode controller. In designing the sliding mode controller, the effectof load disturbance has been taken into consideration to enhance the robustnessof the controlled PWM inverter. Moreover, the upper bound of the load disturbance under which the sliding condition can be maintained has also been derived. The sliding surface of the sliding mode controller is designed such that the behavior of the controlled PWM inverter is optimal subject to the selected cost function.To verify the proposed control schemes, a PWM inverter system based on PC-DSPLab,a dual-DSP based interactive digital controller development system, was constructed for testing. The mechanization of the control software under dual-DSP architecture has been described in detail. Simulation andexperimental results are given to confirm the theoretic analysis and show the effectiveness of the proposed control schemes.