The Optimal Design and Application of Rim Motors for a Novel Powered Wheelchair

本論文之目的為開發第四代創新手輪馬達驅動之電動輪椅，此新型電動輪椅完全改變傳統電動輪椅利用高轉速的馬達搭配減速機構來驅動的方式；而以輪椅手扶圈設計成手輪馬達，直接驅動輪椅，其優點為不需要減速機構，使得空間可以有效利用，重量大幅降低。四分之一的定子與外轉子式馬達結構可以巧妙的將轉子隱藏在手扶圈之內，在手動模式時，施力半徑大；在電動模式時力矩與力矩密度高。 本論文先對電動輪椅的行駛條件作性能估測，並決定馬達的性能規格，選定適合的齒極比與繞線方式後，建立馬達磁路模型，經靈敏度分析後，利用最佳化軟體搜尋最佳尺寸，並使用有限元素分析軟體驗證，修改磁鐵與齒型設計以降低力矩漣波，調整馬達參數在不降低性能的前提下降低馬達重量，最後找出d/q軸的電感關係以求得單位電流的最大力矩輸出。 手輪馬達性能測試結果發現該設計有達到設計目標，最大輸出力矩26.8 ，最高轉速87 rpm。整車測試結果顯示在平地最高速度可達9 km/hr，在斜坡上可達4 km/hr，而在同樣的平地行駛速度下，由手輪馬達驅動的電動輪椅的電流消耗量只有市售電動輪椅的三分之一，且整車重量只有市售輪椅的五分之三，所以本創新電動輪椅具備節約能源及輕量的優點，在市場上極具競爭力。This thesis proposes the design of a powered wheelchair propelled by a 4th generation rim motor module. This novel powered wheelchair changes the driving structure of the traditional powered wheelchair equipped with reduction gears to one that is direct-driven by two rim motors hidden in the push rim. This design simultaneously provides the advantages of lower weight and more hand-drive space. Long torque arm is supplied in the hand-driven mode and high torque and torque density are supplied in the motor-driven mode. First of all, determination of the torque, speed and power based on dynamic evaluation is necessary. After deciding the proper winding type and tooth/pole combination, the magnetic circuit model is constructed. The optimal values of the motor can then be set through sensitivity analysis and an optimal search method. The optimal results are then verified by the Finite Element Analysis (FEA). The magnet and tooth shapes are modified to reduce the torque ripple. Some parameters of the motor are adjusted to reduce the weight without decreasing the output performance. Finally, the d-/q-axis inductances are used to find the maximum torque per ampere (MTPA). The performance test of the rim motor shows that the design goal is achieved. The maximum torque is 26.8 and the maximum speed is 87 rpm. The road test reveals that the maximum speed is 9 km/hr on a level surface and 4 km/hr on an upward slope. Under the same speed on level ground, the powered wheelchair equipped with rim motor modules consumes only one-third the electric power of existing powered wheelchairs available on the current market and is 40 percent lighter in weight. The advantages of energy savings and light weight make this novel powered wheelchair competitive