以PSoC為基礎實現三相風扇馬達V/f無感測控制方法

Abstract

針對弦波型永磁同步馬達的無感測控制，本文提出一種結合V/f純量控制與磁場導向控制的V/f無感測功率因數相角控制方法，此法具有計算簡單、易於實現、穩態響應佳的優點。藉由馬達電壓與電流的相角差(功率因數角度)偵測與修正，以閉迴路控制方式達到最佳效率的控制。此法以磁場導向控制的穩態響應為基礎，計算最佳扭矩效率控制情況的電流相角，此相角為馬達轉速與負載的函數，可先行計算並以查表方式實現以節省計算時間。經由變頻器輸出電壓與電流相角的偵測，以閉迴路控制方式完成最佳相角的控制，間接達到最佳效率控制。此法受限於相角的有效取樣頻率，因此動態響應與梯型波無感測控制相當，但較磁場導向控制為緩慢，其穩態響應則與磁場導向相當，適用於風扇、幫浦等應用領域。為了降低開關損失與提高脈寬調變波的線性控制範圍，本文採用120度導通角的不連續脈寬調變(DPWM)方法。本文量測了永磁同步馬達在V/f控制下的小信號模型，並以此為基礎設計數位式相角控制迴路補償器，整合相角偵測與V/f相角控制，完成了系統的設計與模擬驗證。本文尤其著重應用可程式化系統晶片(PSoC)於無感測控制數位式實現方法的探討，採用意法半導體生產的32位元微控器STM32F051，探討系統操作模式、中斷機制、取樣頻率、數位相位補償器、ADC量化誤差、MCU I/O介面設計等實現議題，完成弦波型永磁同步馬達的無感測控制，實驗結果顯示與模擬分析的一致性以及相較於梯型波無感測控制達到顯著的效率改善效果。

This thesis proposes a V/f power factor angle control scheme for the sensorless control of three-phase permanent magnet synchronous motors (PMSM) in applications to high efficiency fan and blower motor drives. The proposed method combines advantages of V/f scalar control due to its simplicity and robustness and field-oriented vector control (FOC) due to its high efficiency torque control. The optimal power factor angle of the motor drive can be derived based on the phasor diagram of the PMSM under FOC. The power factor angle is under closed regulation with on-line detection of the phase angle and a precalculated phase angle table as its reference command. Small-signal model of the V/f controlled motor drive under decoupled current control has been constructed under perturbations. Based on the constructed model, a loop compensator has been synthesized to achieve required bandwidth and phase margin. The 120-degree conduction discontinuous pulsewidth modulation (DPWM) method has been adopted to reduce the switching losses as well as to enhance the linear control range. This thesis especially focuses on the development of programmable system-on-a-chip (PSoC) implementation techniques of sensorless dive using advanced microprocessors. A new generation of 32-bit microprocessor with ARM Cortex M0 core has been selected for the implementation of the proposed sensorless V/f control scheme. Practical implementation issues such as interrupt mechanism, quantization error effect, sampling frequency selection, etc. have been discussed. Experimental results show consistency with their corresponding simulation results. System performances have been measured and show a better efficiency improvement.