Novel Predictive Current Control for Four-Switch Three-Phase Inverter-Fed Synchronous Reluctance Motors (II)

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Project title

Code/計畫編號

MOST104-2221-E019-013

Translated Name/計畫中文名

三相四開關變頻供電型同步磁阻電動機之新型預測電流控制(II)

Project Coordinator/計畫主持人

Cheng-Kai Lin

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Electrical Engineering

Website

https://www.grb.gov.tw/search/planDetail?id=11493744

Year

2015

Start date/計畫起

01-08-2015

Expected Completion/計畫迄

31-07-2016

Bugetid/研究經費

853千元

ResearchField/研究領域

電子電機工程

由於同步磁阻電動機的結構簡單、堅固和低成本的特性，故它已被廣泛地應用於各種工業應用中。目前，三相六開關變頻供電型同步磁阻電動機驅動系統中所使用的開關切換策略已接近成熟。然而，在三相四開關驅動系統中，仍然有很多改善和發展的空間。因此，新的開關切換方法是值得發展以提供三相四開關驅動系統其他可行的選擇。上述情況激發我們提出這個計畫。本專題研究申請案原為二年期計畫。然而，這個申請案已獲准了一年（103/8/1 ~104/7/31），而它現在正在執行中。為了完整地呈現所提的專題計畫內容，前五個月的相關研究成果會附於本次計畫案中以供參考。以下為這次申請案在第二年（104/8/1~105/7/31）期間的簡要描述：一般情況下，為了在三相四開關驅動系統中節省硬體成本，需加裝兩顆電容以替代某一相上臂和下臂的功率開關。這使得三相四開關變頻器只能產生出四種非零的電壓向量。在缺少零電壓向量的情況下，傳統空間向量脈波寬度調變技術將無法直接地應用至三相四開關驅動系統上。此外，當這兩顆電容上的電壓發生動態地變動時，將會直接影響模型式預測電流控制器的電流預測準確度。為了解決上述問題，在第二年期間（104/8/1~105/7/31），一種改良型無模型式預測電流控制方法將被提出，並實現在三相四開關同步磁阻電動機驅動系統中。所提方法的特色為：計算簡單，且不需要任何電動機參數亦不需要使用電動機的數學模型，只需測量定子電流和記錄三相四開關變頻器在四種不同開關切換模式下所對應的電流差，便可預測未來的定子電流。所提電流控制方法對電動機的參數變化和電容上的電壓變化皆是不敏感的。類似於模型式預測電流控制，在目前取樣間隔內選擇出具有最小成本函數的開關切換模式，該切換模式將在下一次取樣間隔內所採用。最後，我們將以TMS320F2809為核心的數位訊號處理器，針對上述所提的預測電流控制方法進行實驗，以驗證所提方法的正確性和可行性。"Synchronous Reluctance Motors (SynRMs) have been widely used in various industrial applications due to their simple structure, firmness, and low cost. Presently, switching strategies used in the six-switch three-phase (SSTP) inverter-fed SynRM drive systems are mature. Still, there remains considerable space of improvement and development for the four-switch three-phase (FSTP) drive systems. Therefore, it is worth developing different switching methods to provide a viable technology for the FSTP drive systems. The above status motivates us to propose this research project. Originally, this research project was planned for two years. It has been approved for one-year only (103/8/1~104/7/31) and has been running for five months up to now. In order to provide an overall view of this project, the relevant research results as of the first five months are attached as references in this application. A brief description of the application for the next/second year (104/8/1~105/7/31) is given below. Generally, to save hardware costs in the FSTP drive system, two capacitors will be utilized to substitute for the upper-arm and the lower-arm power switches in one of the three phases. This results in four kinds of nonzero voltage vectors generated by the FSTP inverter. In the absence of the zero voltage vector, the traditional space vector pulse-width modulation used in the SSTP drive system may not be directly applied to the FSTP drive system. Furthermore, when the voltages of the two capacitors are dynamically changed in the transient and steady-state operations, the accuracy of current prediction of the model-based predictive current controller will be influenced directly. In order to overcome the above difficulties, an improved model-free predictive current controller will be developed and realized in the FSTP SynRM drive system in the second year (104/8/1~105/7/31). Features of the proposed method include the following: simple computation, no need for the knowledge of motor parameters, and no need to develop mathematical models. To predict future stator currents, one just needs to measure the stator currents and record the current differences under four different switching modes of the FSTP inverter. The proposed method is insensitive to parameter variations of the SynRM and voltage changes of the two capacitors. Following the similar rule used in the model-based predictive current control, the optimal switching mode, which minimizes a cost function, will be selected in the present sampling interval and applied in the next sampling interval. Finally, a digital signal processor, TMS320F2809, will be utilized to validate the correctness and the feasibility of the proposed method."

Keyword(s)

同步磁阻電動機
電流預測控制
延伸型反電動勢
電流變化量
三相四開關變頻器
synchronous reluctance motor
predictive current control
extended back-EMF
current variation
four-switch three-phase inverter

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Novel Predictive Current Control for Four-Switch Three-Phase Inverter-Fed Synchronous Reluctance Motors (II)

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