本文探討電動機車之整合式電驅動系統的散熱設計，此電驅動系統將控制器與電動機結合以節省空間，因其發熱密度高而形成莫大挑戰與本研究之課題。在此先藉有限元素電磁分析軟體JMAG-Designer，求解三相交流感應電動機之能量損失作為實際發熱量，結果顯示在忽略機械雜散損下，電動機以額定功率與最大功率運轉時，定子鐵損分別為60.92 W與79.14 W，且定子銅損為226.85 W及1,052.70 W，而轉子銅損則為79.56 W及248.36 W。接著依理論推算散熱排之對流熱傳係數，並設定厚度0.04 mm空氣層作為定子鐵心與水冷套之接觸熱阻，再藉計算流體力學軟體Fluent針對原型電驅動系統進行熱流場模擬；將計算結果與實測數據相互驗證發現，當電驅動系統以額定功率穩定運轉時，最高溫區域為轉子鐵心與導體且其均溫為89.28 ℃。而以最大功率運行30秒後，溫度最高者為馬達控制器中的MOSFETs，其均溫為88.72 ℃且最高達100.60 ℃；也觀察到運轉15秒以後，其溫升趨勢開始轉為線性上升，因此如何有效控制、減緩MOSFETs之溫升幅度，即成為本電驅動系統之主要探討目標。
在檢視相關流場後，將控制器水冷板之散熱鰭片改為交錯式之平行四邊形Pin Fins，使流體均勻分布而能充分與鰭片接觸，並可達到抑制迴流產生之效果，進而提高鋁基板之整體散熱效率；同時將感應電動機水冷套由原先的串聯式設計，改為階梯狀並聯式之散熱水道，使流動阻抗降低並成功地提高整體水流量。結合上述兩項改善方案後，模擬結果顯示MOSFETs於電驅動系統以最大功率運轉時，其平均溫度得以降低7.2度至81.53 ℃，而最高溫度則大幅下降11度至89.69 ℃。總而言之，本文成功地結合數值與實驗兩工具設計出能有效控制MOSFETs溫升之散熱模組，亦透過數值與實測之結果比較驗證，確立所建構的數值模型的建構與模擬方法具有良好可信度，可供日後探討電動機散熱設計之參考應用依據。

This work focuses on the thermal management of an electric power system for motorcycle, which integrates the electric motor, transmission, and control units intimately to possess the compact and versatile features for fitting into multiple applications. However, the summed heat amount generated by motor and control unit forms a challenging thermal task and becomes the topic of this thesis. Here, a systematic design scheme of the thermal module is established by considering the concerns on both electromagnetic and thermal aspects. Firstly, commercial software JMAG-Designer is used to simulate the electromagnetic field for providing information to calculate core and copper losses in a rational manner. As a result, the summation of core and copper losses are 367.3W and 1,380.2W for the cruising and accelerating operations, respectively. These quantities with the dissipation add-ons from control unit are the total heat energy needed to dispel by the water-cooling thermal module. Next, CFD codes Ansys Fluent is utilized to check the steady and the transient thermal/flow distributions inside the original power system. The steady simulation illustrates that the highest temperature is found in the core with an average temperature of 89.3 ℃. Also, for the unsteady calculations, the maximum temperature 100.6 ℃ is recorded in the MOSFETS with an average temperature 88.7 ℃ after a 30-second accelerating operation. Clearly, the temperature rise and distribution of MOSFETS become the main improving target. Moreover, this CFD model is validated by means of a consistent trend between the experimental measurement and the numerical result.
Subsequently, the water-cooling heat fins in the control unit is changed from the parallel plate fins to the offset-array pin fins for reducing the flow recirculation and increasing the effective heat dissipation area. Also, the parallel arrangement of coolant ducts for the motor unit is adopted to replace the original in-series duct layout to decrease flow resistance of the entire cooling duct for enlarging the operating flow rate. Accordingly, CFD calculations illustrate that this new thermal design with the above modifications yields the impressive 7.2℃ and 10.9℃ temperature decreases on the average and the highest temperature on MOSFETs after the 30-sec maximum-power operation. In summary, the analysis tool proposed here has successfully generated an efficient thermal solution to control the motor core and MOSFETs temperatures below their safety limits. Also, the accomplishment of this research offers a rigorous and systematic scheme to design a water-cooling thermal module for the thermal management of an integrated electric power transmission system used in motorcycle.

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