本文為了補償因霍爾元件定位不精準或濾波器造成的相位延遲,將提出一擾動法自動調整驅動相角,來達到提升無刷直流(BLDC)風扇馬達運轉效率。不同於傳統的驅動相角自動調整裝置與無感測器之三相無刷馬達驅動相角自動調整裝置,本篇提出的方法不需分別對不同的馬達與環境製作特性曲線表或需有經驗的人調整其參數,就可以達到最佳效益。在單相方面將直接使用硬體相移器調整霍爾訊號來改變換相點,驗證調整驅動相角可達成以上效益。而在三相方面將使用軟體相移器與端電壓比較法無感測驅動方式搭配擾動法自動調整驅動相角來達成以上效益。最後實驗驗證此簡單的擾動法自動調整驅動相角可有效的找到最佳效率點,而對於長時間運轉的機器可依使用者需求設定特定時間來重新搜索最佳效率點。本文以dsPIC30F4011 為整個系統的主要核心,將相移器數位化,並使用簡單的判斷方式,能有效的簡化電路,降低整體驅動系統的開發成本。In order to compensate improper location of hall sensor or phase delay of filter, this paper proposes the perturbation approach to adjust commutation phase automatically for improving the efficiency of brushless DC (BLDC) motor in fan application. Different from the traditional approach needs the motor-environment characteristic or adjusts the parameters by experienced engineer, the proposed method can achieve the optimal point in commutation. For single-phase motors, we design a phase adjusting circuit to change commutation. This way is useful to improve the efficiency. On the other hand, we design digital phase compensation with sensorless terminal voltage comparison method and phase adjustment strategy by using perturbation in three-phase motor. Finally, experiment results show the proposed method can search the optimal commutation point successfully. Besides, users can set the searching time according to the operation condition.The micro-controller dsPIC30F4011 is used as the central control unit to implement the digital filter and algorithm, moreover, it could effectively simplify the circuit and reduce the cost of motor driver system.