以FPGA實現直流無刷馬達無位置感測控制

Abstract

直流無刷馬達具有高可靠度、高效率及可控制性等優點，已被廣泛應用於各種場合。 然而，直流無刷馬達需使用霍爾元件來偵測轉子與定子間的相對位置。霍爾元件在使用上通常有幾點限制：感測器必須擺放精準才能正確得到轉子位置、易受雜訊干擾且不耐高溫。因此，沒有使用霍爾元件的無感測控制技術則可以改善上述缺點。 本論文以現場可規劃邏輯閘陣列(Field Programmable Gate Array, FPGA)實現應用於直流無刷馬達無位置感測控制晶片，其電路實現方式以階層式、模組化設計，降低其複雜度。以並行電路的概念，降低邏輯閘使用數量，達到最佳化目的。直流無刷馬達無位置感測策略為以120度方波脈波寬度調變為驅動；以反應電動勢偵測電路偵測應電勢之零交會點為基礎。利用零交會點來得到準確的開關換相點，進而達到驅動與控制的目的。 最後利用模擬與實作結果來驗證所提無位置感測控制策略。

Brushless DC motors (BDCMs) with high reliability, high efficiency and good controllability are extensively used. However, the BDCMs must use Hall sensors to detect the relative position of the rotor and the stator. It leads to the limitation that the Hall sensors must be mounted properly in the motor in order to acquire the exact rotor position, ease of interference with noise and temperature failure. The BDCM sensorless control schemes can overcome the limitations. This thesis presents the design and implementation of FPGA-based sensorless control for BDCMs. By using the hierarchical and modular realization strategy, the designed parallel circuit can reduce the design complexity and the total gate counts for optimum design. The proposed BDCM sensorless control fed by 120-degree square-wave-pulse-width-modulation (SWPWM) approach obtains the zero crossing points by the back-EMF detecting circuit. In addition, accurate commutation instants can be obtained by those zero crossing points. Simulation and experimental results have been carried out to verify the proposed control scheme.