Design and Implementation of Predictive Current Controllers for Interior Permanent-Magnet Synchronous Motor Drive Systems Based on Dual Switching Technique

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Project title

Code/計畫編號

MOST106-2221-E019-053

Translated Name/計畫中文名

內藏式永磁同步電動機驅動系統之基於雙切換技術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=12282589

Year

2017

Start date/計畫起

01-08-2017

Expected Completion/計畫迄

31-07-2018

Bugetid/研究經費

748千元

ResearchField/研究領域

電子電機工程

由於永久磁鐵是埋藏在轉子中，使內藏式永磁同步電動機擁有結構堅固和高效率的特性，並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內藏式永磁同步電動機驅動系統中所使用的以單切換為基礎的預測電流控制技術已接近成熟，該技術是在每一個取樣週期內只施加一個電壓向量。然而，使用所提以雙切換技術為基礎的預測電流控制器，在理論上應具有更令人滿意的電流追蹤效能。該電流控制器將在每一個取樣週期內施加二個電壓向量。該二個電壓向量所對應的導通時間是可透過最佳化的過程來加以調整。因此，適用於三相六開關變頻供電型內藏式永磁同步電動機的新型預測電流控制器是值得研究的，以期能有效降低電流漣波並改善電流追蹤的效能。上述情況啟發我們提出一個二年期計畫。在所提的計畫中，我們將在兩年內開發兩種預測電流控制器。第一種是以雙切換技術為基礎的模型式預測電流控制器，它是以離散時間數學模型為基礎。第二種是以雙切換技術為基礎的無模型式預測電流控制器，它是基於定子電流的量測。在第一年期間（2017 年8 月1 日至2018 年7 月31 日），我們計畫開發一種以雙切換技術為基礎的模型式預測電流控制器，其中將使用到內藏式永磁同步電動機的等效離散時間模型。使用這個模型時，定子電阻、q 軸電感和延伸型反電動勢會被使用以預測未來的電流。從概念上講，我們將設計一個成本函數，它可以量化電流命令和三相六開關變頻器在不同雙切換模式下所對應的電流預測值之間的電流誤差。依據此成本函數，在不同雙向量開關切換模式下所對應的最佳導通時間是可以被各別計算的。在目前的取樣週期中，具有最小成本函數的雙切換模式是被選擇的。所對應的二個切換模式和最佳施加時間將在下一次取樣週期內被施加。在第二年期間（2018 年8 月1 日至2019 年7 月31 日），一種以雙切換技術為基礎的無模型式預測電流控制器將被開發，以實現在三相六開關內藏式永磁同步電動機驅動系統。這種電流控制方法，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六開關變頻器在不同雙向量開關切換模式下所對應的電流差。為了提升預測的準確度，一種新的預測誤差修正方法在此計畫中是被提出。所提預測電流控制器的主要優點是對電動機的參數變化不敏感。根據雙向量模型式預測電流控制中的相同規則，最佳的雙切換模式和所對應的施加時間是在目前取樣週期內被選擇和計算，並將在下一次預測週期內採用。值得注意的是，在每次的取樣週期內，定子電流將會被量測二次。最後，我們將針對上述兩種預測電流控制器進行實驗以驗證所提方法的正確性和可行性。"Since the permanent magnets are buried in the rotor, the interior permanent magnet synchronous motor (IPMSM) has the characteristics of strong structure and high efficiency, and it has been widely used in various industrial applications. Currently, the single-switching-based predictive current control (SSBPCC) techniques, which apply only one voltage vector in each sampling period, used in the six-switch three-phase (SSTP) inverter-fed IPMSM drive system are nearly mature. However, using the proposed predictive current controllers based on a dual switching technology in theory should have the more satisfactory current-tracking performance. The current controllers will apply two switching states in each sampling period, whose conducting times can be adjusted by an optimization process. Therefore, studying new predictive current controllers for the SSTP inverter-fed IPMSM drive system is worth for effectively reducing the current ripple and improving the current-tracking performance. The above circumstances motivate us to propose a two-year project. In this project, we will develop two predictive current controllers. The first one is called dual-switching-based model predictive current controller (DSBMPCC) which is based on a discrete-time mathematical model. The second one is dual-switching-based model-free predictive current controller (DSBMFPCC) which is based on measuring stator currents. In the first-year period (2017/08/01~2018/07/31), we plan to develop a DSBMPCC, in which an equivalent discrete-time model of IPMSM will be employed. With this model, the stator resistance, the q-axis inductance, and the extended back-EMF of the IPMSM are used to predict the future current. Conceptually, we will design a cost function, which can quantify the current errors between the current commands and the predicted currents under different two-switching modes to be generated by the SSTP inverter. Based on this cost function, the corresponding optimal applying times under different two-switching modes can be individually calculated. In the present sampling period, a two-switching mode that minimizes the value of the cost function is selected. The corresponding two switching states and the optimal applying times will be applied in the next sampling period. In the second-year period (2018/08/01~2019/07/31), a DSBMFPCC will be developed and realized in the SSTP IPMSM drive system. This current control method will not require any knowledge of the motor parameters nor its mathematical model. Only measuring the stator currents and recording the current differences under different two-vector switching modes of the SSTP inverter are required. In order to improve the prediction accuracy, a new prediction error correction method is proposed for this project. The main advantage of this DSBMFPCC is that it is insensitive to motor’s parameter variations. Following the same rule in the DSBMPCC, the optimal two switching states and the corresponding applying times are selected and calculated in the present sampling period, and they will be applied in the next sampling period. It is worth noting that the stator current will be measured twice in each sampling period. We will conduct experiments to validate the two predictive current control methods aforementioned, verifying the correctness and feasibility of the proposed methods."

Keyword(s)

內藏式永磁同步電動機
預測電流控制
延伸型反電動勢
電流變化量
三相六開關變頻器
interior permanent magnet synchronous motors
predictive current control
extended back-EMF
current variation
six-switch three-phase inverter

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Design and Implementation of Predictive Current Controllers for Interior Permanent-Magnet Synchronous Motor Drive Systems Based on Dual Switching Technique

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