新型永磁無刷變極馬達之設計與分析

Abstract

電動車用輪內馬達之設計在近年來已成為一個重要的課題。在汽車行進間，常會依據路況不同來調整適合的速度。而傳統調整馬達轉速的方法即為使用變速機構，但齒輪間的摩擦會使得能量被消耗在機構中，令輸出效率低落。雖然現今在馬達的變速研究上已出現了改變感應馬達定子極數等高效率的方法，但因永磁馬達在設計時已將磁鐵極數固定，故無法透過一般的變極方法來達到高效率的變速效果。本研究的目的在於設計電動機車用之永磁無刷直流馬達與變極方法。以記憶馬達的原理為基礎，藉著在變極時產生突波，改變馬達之磁鐵極性，將感應馬達的變極原理應用至永磁無刷直流馬達上，此方法不但能保有永磁馬達高效率的特性，亦可產生具有較大轉速的效果。在論文中提出了使用共同繞組的變極方法，針對該方法設計控制器並估算其性能。根據模擬所得之力矩-轉速曲線，該永磁變極馬達能夠藉由極數的變換，得到比單一極數馬達更大的轉速與啟動扭矩，且該馬達在適當的極數變換下亦能達到所訂定之規格。

Design of in-wheel motors for electric vehicles has already attracted attention in recent years. Electric vehicles require the capability of both large starting torque and wide speed range to cope with various road conditions. Traditional approaches involve using a shifting mechanism, but friction between gears results in unnecessary energy consumption and makes motor inefficient. Nowadays, lots of researches to make motors efficient such as changing the number of poles have already been proposed. But in permanent magnet machines, magnetization has been signed at first and can not be changed. Therefore, conventional approaches are not suitable for permanent magnet machines.The purpose of this study is to design a brushless permanent magnet DC motor with pole-changing method for electric vehicles. By generating a pulse when changing the number of poles, magnetization of magnets can be changed appropriately and the principle of pole-changing motors can be applied to permanent magnet machines. This pole-changing method can not only retain the feature of permanent magnet machines in efficiency, but also acquire wide speed range. In this study, a pole-changing method using common windings has been proposed. Performance of brushless permanent magnet DC pole-changing motors has been simulated with model construction. According to the T-N curve, the proposed brushless permanent magnet pole-changing motor can obtain larger starting torque and wider speed range than the motors with fixed number of poles. In addition, expected performances are also achieved with performing pole-change properly.