基於檢流電阻脈波寬度調變變頻器之內藏式永磁同步馬達凸極位置感測驅動

Abstract

永磁同步馬達於低速與零速的無角度感測器位置估測通常仰賴馬達凸極轉子的角度資訊，為了激發並以可行信噪比量測馬達本身的凸極角度，使用電壓源變頻器進行高頻電壓注入已成為利用永磁馬達凸極性進行角度估測的關鍵。 本論文透過一系列方法改善內藏式永磁馬達凸極性角度、估測，其中包含注入訊號的選擇、脈寬調變直接電壓注入方法、與量測電壓向量合成注入。首先為了釐清使用弦波電壓與方波電壓注入進行角度估測的效能差距，兩者的角度解調變與對系統非線性之關係皆透過理論與實驗評估，同時，本論文提供針對同開關切換頻率下之不同注入訊號比較，可供讀者適當地選擇注入訊號。 接著考量到以切換頻率進行電壓注入時，馬達三相電流需在一次脈寬調變週期中進行多次採樣來估測角度，此採樣需求會導致切換頻率電壓注入無法在使用檢流電阻進行電流量測的驅動器上以空間向量脈寬調變實現。為了解決此問題，本論文提出新型脈寬調變法進行高頻電壓注入，透過此方法可在一次脈寬調變週期中進行至少兩次的瞬間相電流量測，進而於檢流電阻架構驅動器上實現切換頻率電壓注入。 使用對稱式脈寬調變方法進行切換頻率電壓注入會影響其馬達電壓波型，為了實現凸極性角度估測，透過修改脈寬調變波形進行電壓注入便成為估測頻寬與穩態估測誤差之間的平衡選擇。本論文透過量測電壓向量進行高頻注入，提出量測向量與不連續脈寬調變整合之新型脈寬調變電壓注入方法，藉由此方法可使馬達在維持對稱式脈寬調變驅動的同時亦維持高頻電壓的注入。提出之方法改善了凸極性無感測器驅動的電壓諧波、電流諧波以及角度估測誤差，因此提出之方法可以達到相較於現行方法更高的速度估測頻寬。實驗證實此調變方法適用於內藏式永磁馬達之無位置感測驅動，並具有對檢流電阻電流量測驅動器的相容性。

Self-sensing saliency-based position estimation of permanent magnet (PM) synchronous machine at zero and low speed generally depends on the spatial information in machine saliency. To excite the machine saliency with voltage source inverter with feasible signal-to-noise ratio, the injection of high-frequency (HF) voltage is essential for PM machine position estimation. This dissertation improves the saliency-based position estimation on interior PM (IPM) machines. They include the selection of injection voltages, directly pulse-width modulation (PWM) voltage injection, and the measurement vector insertion (MVI) integration. To clarify the performance difference between sinusoidal and square voltage injection, the position demodulation process and system nonlinearities are both theoretically evaluated. Meanwhile, the comparison between sinusoidal and square voltage injection under a specific switching-frequency is also provided for selecting proper injection signal. Considering the switching frequency injection, multiple phase currents should be sampled per PWM cycle instead of single average current. It leads to the implementation issue on the space-vector PWM (SVPWM) inverter using shunt resistor current sensing for machine control. A modified PWM injection instead of SVPWM injection is proposed for the saliency-based drive using shunt-based current sensing. It is concluded that at least two transient currents can be sampled per PWM cycle based on the proposed PWM voltage injection. The switching frequency voltage injection distorts the symmetric PWM voltage pattern. For these saliency-based drives, the PWM injection estimation is the tradeoff between transient estimation bandwidth and steady state estimation error. Under this effect, a modified PWM voltage injection is proposed through the MVI for position estimation. By integrating the MVI with discontinuous PWM (DPWM), the injection maintains the symmetric PWM voltage for machine control. This MVI based PWM (MVIPWM) improves the saliency-based drive among voltage harmonics, current harmonics and position estimation error. As the result, proposed MVIPWM shows higher speed estimation bandwidth than state-of-the-art injection with SVPWM and DPWM. This dissertation concludes that the MVIPWM injection is best suited for interior PM machine saliency- based drive. This MVIPWM injection is also compatible with shunt-based inverters at low cost.