交流感應馬達驅動系統盲點時間效應補償及電路實現

Abstract

脈寬調變技術已廣泛的應用於控制換流器電力開關元件切換的時間。為避 免換流器內同一臂上的兩個電力開關元件同時導通~，導致直流鏈電源短 路而造成電力開關元件的損壞~，必須在控制信號傳送至電力開關元件之 前加入盲點時間的處理。然而此盲點時間的加入~，也使得換流器的輸出 品質受到影響；盲點時間的效應不僅造成換流器輸出基本波的振幅減小~ ，在低電壓源供應時馬達除了提早卡住不轉~，還產生了一些非我們所要 的低次諧波成份。另外~，電力開關元件的物理性切換時間亦是影響換流 器輸出品質的另一重要因素。在本論文中我們依據盲點時間對換流器輸出 影響的特性~，利用電壓回授的方法對正弦脈寬調變換流器做補償。根據 模擬及實驗的結果~，證明了即使在未知電子元件開關延遲特性及盲點切 換時間~，我們的補償器皆能有效的將盲點效應消除~，大大的提升換流器 輸出正弦訊號的精準度。 The pulse-width-modulation (PWM) techniques have been widely applied incontrollingthe power switching elements of inverters. In order to preventthe pair of power switching elements in an arm of the inverter from (1)conducting simultaneously (2)causing a short-circuit of the DC link, and (3)resulting in the power switching elements consuming extra high power,a switching dead time is added in every switching pulse.Although the dead time providessafe operation, it adversely affects the performance of the inverter.It not only decreases the amplitude of fundemental output voltagebut also produces low-order harmonic voltage.The minimum armature voltagefor rotating the motor is also increased by the usage of dead time control.In this thesis, in order to minimize dead-time effects occurred ininverter, we propose a new compensation method where three-phase output voltage are fed back for generating the compensation signal for our sinusoidal PWM inverter. Our simulation and experimental results have shown that our compensator can greatly eliminate the dead-time effectseven though thedelay time of power switching elements are unknown.