五相永磁式同步電動機的設計與驅動器研製

摘要：五相永磁式同步電動機的優點為故障容忍度高、可分散驅動功率轉換器輸出電流、高可靠度及電機安全性。文內提出20極22槽，內轉型五相永磁式同步電動機的設計，其定子的外徑為220 mm。並以有限元素磁路分析套裝軟體Maxwell-2D進行電動機之磁路、頓轉轉矩及感應電動勢之分析，完成優化的設計。定子採用全開口的槽，可簡化製作過程。

五相永磁式同步電動機之驅動系統，其功率轉換器採用五相五臂型變頻器，控制策略以線性霍爾效應元件偵測轉子角位置信號，並利用數位霍爾效應元件的信號作轉速之估測。此外，本文內所述之系統亦藉電流感知器偵測相電流，且以上述的回授信號完成轉速及各相電流閉迴路控制，提高轉速響應、降低電流諧波含量與增進系統效率。本文採用32位元數位信號處理器TMS320F28069作為控制核心，在驅動系統中，轉速及相電流控制策略皆由軟體完成。本系統之直流鏈輸入電壓為70 V，在轉速800 rpm及電磁轉矩8.16 Nm時，整體效率為84.4 %，電流總諧波失真率為1.47 %，實測結果驗證了本文控制策略的可行性。

Abstract: The advantages of five-phase permanent-magnet synchronous motor (PMSM) are high fault tolerance, dispersible power converter output current, high reliability and electrical safety. This paper presents the design of a 20-slot 22-pole inner-rotor type PMSG. Its outer diameter is 220 mm. The finite element software package, Maxwell-2D, is used to analyze the magnetic circuit, the cogging torque as well as the induced electromotive force (EMF) to optimize the performance of the motor. To simplify the production process, full opening of the slots on stator is adopted.

This paper presents the design and implementation of a five-phase permanent-magnet synchronous motor (PMSM) drive system. Five-phase five-leg power inverter is proposed to drive the five-phase PMSM. In addition, linear and digital Hall-effect sensors are used to detect the rotor positions and the rotational speed, while the current sensors detect the immediate current of each phase and transmit to digital signal processor for calculation. Finally, closed-loop speed control strategy is realized in accordance with the feedback signals to obtain speed response with low harmonic distortion as well as raising the overall efficiency of the system. In this paper, the 32-bit digital signal processor, TMS320F28069, is adopted as the control core. In the driving system, the speed and phase current closed-loop control is conducted by software. The input dc-bus voltage of the system is 70 V. At 800 rpm and 8.16 Nm, the overall efficiency and the total harmonic distortion of current are 84.4 % and 1.47 %, respectively. Experimental results confirm the feasibility of the proposed control strategy.

關鍵詞：五相永磁式同步電動機、表面嵌入式磁鐵、轉速及相電流閉迴路控制

Keywords：Five-Phase Permanent-Magnet Synchronous Motor, Surface Mounted Permanent Magnet, Speed and Phase Current Closed-Loop Control

前言
早期永磁式電機多朝三相發展，而多相(三相以上)的電動機可降低轉矩漣波，並可增加故障容忍度，可允許如電壓開路、電流短路、電源故障、控制元件故障等情況，甚至永久性的故障也可以隔離後繼續運作[1-2]。

永磁式電動機設計上參考三相或六相電動機的設計，除了應達到需求的功率、電壓以外，亦考慮矽鋼片磁通密度、頓轉轉矩、諧波失真率等。本文在馬達設計的特色為：

1.五相電機設計，提高電動機之可靠度。
2.以嵌入式磁鐵作設計，提高轉子可靠度。
3.定子槽部設計為完全槽開口，方便繞組。
4.定子繞線線架設計，減少組裝時間且製具可同時作為絕緣用途。

在驅動方面，隨著功率電晶體開關元件規格及數位微處理器運算速度的提升，使得五相電動機之系統逐漸在市面上蓬勃發展本系統架構為五相變頻器[3-4]配合控制策略，並著重於驅動系統之控制。