具有可調輸出電壓功因修正器之無刷直流馬達驅動器的效率改善策略

Abstract

本論文提出以可變輸出功率因數修正(variable output voltage power factor ccorrection, VOPFC)轉換器與變頻器整合，發展一具有高效率、高功因之整合式家用變頻壓縮機驅動器。此VOPFC為串聯式升/降壓電路架構，透過兩組功率開關控制輸入電流追隨輸入弦波電壓，達到降低電流總諧波失真比(total harmonic distortion, THD)、提升功率因數之目的，同時可不受輸入電壓大小之限制，實現廣範圍輸出電壓特性；在壓縮機馬達低速運轉時提供低電壓，馬達高轉速運轉下則提供高電壓。在維持相同電流漣波比例條件下，低電壓操作時，可降低後級變頻器之開關切換頻率，大幅減低開關切換損失，提升整體工作效率，而在高電壓操作下，可使系統具有較佳之動態響應及高轉速的能力。本文之發展平台以數位信號處理器(TI TMS320LF-2407A)完成包含前級功率轉換器之電流、電壓迴路及後級變頻器之馬達電流、速度閉迴路，完成一個額定功率500W、功率因數達0.99的PWM/PAM變頻驅動器，速控範圍為50-3000 RPM：此驅動器具有串聯通訊介面，可由外部下達速度命令與設定控制參數，利於壓縮機變頻系統整合。

This thesis proposes the integration of variable output voltage power factor correction (VOPFC) converter and inverter to develop a high efficiency, high power factor and variable speed compressor driver applied in household applications. The VOPFC converter is a cascaded buck-boost converter with two power switches to regulate the input line current with low total harmonic distortion (THD) and at the same time to maintain an adjustable dc-link voltage which can be either higher or lower than the peak of the rectified line voltage. When the motor rotated in lower speed, VOPFC converter supplied the lower voltage. On the contrary, VOPFC converter output the higher voltage which can supply motor driver for the better dynamic response and higher speed. The output inverter stage can be operated in pulse amplitude modulation (PAM) mode or PWM mode with reduced switching frequency for efficiency optimization of the compressor motor driver to maintain a constant V/Hz ratio with specified current ripples. The development platform used in this thesis utilizes a DSP (TI TMS320LF-2407A) to provide a pre-stage power factor converter with current and voltage control loops and a post-stage motor voltage with speed control one. A PWM/PAM motor driver with rated power of 500W, 0.99 power factor, and speed range of 50-3000 rpm is implemented. This motor controller also comprises a serial communication interface which allows external speed command and parameter setting, thus facilitates the integration of the variable frequency compressor driver.