Design and Implementation of Predictive Current Controllers for a Three-Phase Two-Level Voltage Source Inverter with a Lc Filter

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Project title

Code/計畫編號

MOST105-2221-E019-059

Translated Name/計畫中文名

三相二階層電壓源變頻器含電感電容濾波器之預測電流控制器的設計與實現

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=11878537

Year

2016

Start date/計畫起

01-08-2016

Expected Completion/計畫迄

31-07-2017

Bugetid/研究經費

814千元

ResearchField/研究領域

電子電機工程

三相二階層電壓源變頻器已被廣泛地應用至電力電子及電動機驅動的領域，這是由於它在直流轉交流的所有電路拓撲結構中是最具代表性的。三種典型的開關切換策略已成功地實現在三相二階層電壓源變頻器，分別為脈波寬度調變、空間向量脈波寬度調變及電流磁滯控制。另外，在2007年，模型式預測電流控制技術被成功地實現在三相二階層電壓源變頻器。在那之後，模型式預測電流控制成了當前熱門的研究主題之一。因此，開發新的預測電流控制技術(稱作無模型式預測電流控制器)以提供三相二階層電壓源變頻器其他可行的開關切換策略是值得去研究的，以改善模型式預測電流控制的缺點。上述的可能性激發了我們去提出這個研究計畫。本專題研究申請案為一年期計畫(2016/8/1~2017/7/31)。為了讓實驗結果是更完整及豐富的，我們將在一年內實現兩個電流控制器分別以模型式預測電流控制和無模型式預測電流控制為基礎。在上半年(2016/8/1~2017/1/31)中，我們將模型式預測電流控制器實現在三相二階層電壓源變頻器含電感電容濾波器的系統上，所使用的模型式預測電流控制器是以三相電阻電感負載的離散時間數學模型為基礎。電流預測是可以被達成的，藉由使用此負載的電阻和電感參數以及量測的線對線電壓和負載電流。而在下半年(2017/2/1~2017/7/31)中，我們擬將所提的無模型式預測電流控制器實現在三相二階層電壓源變頻器含電感電容濾波器的系統上，此電流控制器是以量測負載電流為基礎。在每次取樣週期內，負載電流將會被偵測一次。接著，使用減法運算，在不同開關切換模式下的電流變化量便可被計算和記錄。根據偵測的電流值和之前的電流變化量，便可以預測出在下一次取樣週期內，所有可能的開關切換模式下所對應的未來定子電流值。類似於模型式預測電流控制器所使用的規則，在目前取樣週期內選擇出具有最小成本函數的開關切換狀態，該切換狀態將在下一次取樣週期內被採用。如此，即可達成控制電流的目的而不需要採用任何的脈波寬度調變技術。無模型式預測電流控制器的主要特色，包括：計算簡單，不需要加裝電壓感測器，不需要使用三相負載的離散時間數學模型及相關參數。相較於模型式預測電流控制器，所提無模型式預測電流控制器更適合用於三相二階層電壓源變頻器含電感電容濾波器的系統中。最後，驗證時將採用TMS320F28335為核心的數位訊號處理器搭配業界生產的變頻器，三相電阻電感負載及電感電容濾波器，實現這二種電流控制器並做相關的比較實驗以驗證其可行性與正確性。所得的實驗結果將可能為目前現有的三相二階層電壓源變頻器的開關切換策略帶來新的視角，即不需要使用任何的脈波寬度調變技術仍可有效控制負載電流的目的，並有機會進一步將此技術移轉至工業界，以提升國內三相二階層電壓源變頻器的研究水平。"Three-phase two-level voltage source inverter (TPTLVSI) has been widely applied to areas of power electronics and motor drive, because it is the most representative in all DC-to-AC circuit topologies. Three typical switching strategies have been successfully implemented in the three-phase two-level voltage source inverter, that is, pulse width modulation, space vector pulse width modulation, and current hysteresis control, respectively. Besides, in 2007, the model-based predictive current control (MBPCC) technology has been successfully implemented in a TPTLVSI. After that, the MBPCC has become one of the hottest research topics currently. Therefore, developing a new predictive current control, called as model-free predictive current control (MFPCC), is worth to study so as to provide the other possible switching strategies for TPTLVSIs. The above possibilities inspired us to propose this research project. This research proposal will be planed to last a year (2016/8/1~2017/7/31). In order to make the experimental results be more complete and abundant, we will implement two current controllers based on the MBPCC and MFPCC in one year, respectively. During the first half year (2016/8/1~2016/7/31), the MBPCC will be designed and implemented on a TPTLVSI with an LC filter. The MBPCC is based on a discrete-time mathematical model of a three-phase RL load. The current prediction can be achieved by using the parameters of the resistance and the inductance in the three-phase RL load as well as the measured line-to-line voltages and load currents. During the second half year (2017/2/1~2017/7/31), the MFPCC will be designed and implemented on a TPTLVSI with an LC filter. The proposed MFPCC is based on the load current detections. First, the load current will be detected once in each sampling period. Next, by using the subtraction method, the current variations under the different switching states can be calculated and recorded. Then, according to the sampled load currents and the previous current variations, the future load currents under all the possible switching states in the next sampling period can be predicted. By following the similar rule used in the MBPCC, the switching state that minimizes a cost function will be selected in the present sampling period and applied in the next sampling period. Therefore, any PWM technology is no longer required, but the purpose of current control can still be achieved by using the MFPCC. The main advantages of the MFPCC are that the calculation is simple, and voltage sensor is not required, and the load parameters are not needed to be known. Compared to the MBPCC, the proposed MFPCC is more suitable for the TPTLVSI with an LC filter. Finally, to verify their feasibility and functionality, we will do some comparative experiments by using a digital signal processor (TMS320F28335), an industrial inverter, a three-phase load, and an LC filter to realize the MBPCC and the MFPCC. The obtained results will bring a new perspective of the switching strategies for the TPTLVSI, achieving the purpose current control without using any PWM technology. The MFPCC is hopeful to further transfer to industry, enhancing the research level of the TPTLVSI in Taiwan."

Keyword(s)

三相二階層電壓源變頻器
數位訊號處理器
預測電流控制
電感電容濾波器
Three-phase two-level voltage source inverter
digital signal processor
predictive current control
LC filter

DSpace CRIS

Design and Implementation of Predictive Current Controllers for a Three-Phase Two-Level Voltage Source Inverter with a Lc Filter

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