無位置感測器直流無刷馬達之設計與實現

Abstract

直流無刷馬達由於簡單的構造、堅固、高可靠度等優點，在日常生活中或工業被大量的應用。一般的直流無刷馬達轉速需要在轉子軸上加裝霍爾元件(Hall sensor)，用來偵測轉子轉速並回傳訊號到數位處理器(DSP)，來達到速度控制效果。但是高溫的環境下，或是縮減體積和成本情況下，不適合裝上霍爾感測器，所以利用無感測控制方法做本文研究方向。 本論文分為兩種方式做無感測控制，第一種為線對線電壓差法，這方法直接利用三相端電壓直接估測反電動勢零交越點，位移 進行換相；第二種為干擾觀測器(Disturbance bserver ,DOB)法，透過馬達輸入電壓、輸出電流直接估算反電動勢換相點。 實驗使用的儀器為德州儀器TMDSHVMTRPFCKIT開發套件，他將端電壓經過電阻、電容電路，使得端電壓訊號有所延遲，本文利用相位補償法改善估測的零交越點和換相點的相位延遲，此外，還利用干擾觀測器本身消除雜訊的功能，增加估測換相點的準確性。 在H-PWM-L-ON切換下，將干擾觀測器法與線對線電壓差法互相比較換相的準確性，由於干擾觀測器法直接估測換相，讓換相較為準確，使得造成的脈動電流(pulsating current)比線對線電壓差法還要小；但是H-PWM-L-ON本身會有非導通相產生電流漣波，所以引入PWM-ON-PWM切法，將干擾觀測器法結合線對線電壓差法與只使用線對線電壓差法相互比較換相的準確性，由於干擾觀測器法結合線對線電壓差法估測到每個換相點與零交越點，使得換相較為精確，讓造成的脈動電流(pulsating current)比單一使用線對線電壓差法還要小。

This thesis explores two methods to do senseless control. The first method is the line-to-line for voltage method by using three terminal voltage to directly estimate the back-EMF zero crossing. The second method is the disturbance observer (DOB) method which estimates the zero crossing point of the back-EMF motor directly by using the motor output current and voltage. The instrument used in this thesis, the Texas Instruments TMDSHVMTRPFKIT implementation kit, uses the method where voltage passes through resistors and capacitor, causing delay to the voltage signal. In our thesis, we use phase compensation method to improve the phase lag at the zero crossing point and phase change point, which are used as the estimation point. Other than that, we also use DOB to improve the accuracy of the phase change estimation point. First, during the H-PWM-L-ON switch, the accuracy of phase change is compared between the DOB method and the line-to-line voltage method. The phase change estimation of DOB method is more accurate as the phase change is estimated directly, and as a result, the pulsating current is lower than line-to-line voltage method. Nevertheless, the non-conductive phase of H-PWM-L-ON will cause current ripple, and so we introduce the PWM-ON-PWM switching method in which we combine DOB method and line-to-line voltage method and compare it with just the line-to-line voltage method for the accuracy. The combination of DOB method and line-to-line voltage method provides a better phase change accuracy, as this method can estimate each of the phase changing point and zero crossing point. As a result, the pulsating current is lower than just using line-to-line voltage method.