空間向量脈寬調變暨柔性切換之換流器設計

Abstract

應用柔性切換技術（切換於零電壓或零電流）於功率換流器上可以有效的改善其性能，例如：提高工作頻率以離開人們的音頻範圍，降低電磁干擾（EMI），減少切換損及限制功率開關元件之dv/dt、di/dt等切換應力。本論文所使用之半共振式直流鏈（Quasi-Resonant dc link）柔性切換電路，此電路於換流器上需外加兩個開關，一個功率二極體、電感及電容，而且所加入之開關亦為柔性切換，因此額外之能量損失可降至最少。如此之半共振式電路可於直流鏈上產生出零電壓，使換流器開關恰切換於零電壓處。另外調變策略為使用空間向量脈寬調變（Space-Vector PWM）捨棄傳統之正弦脈寬調變（Sinusoidal PWM），SPWM無法完全使用直流鏈電壓、諧波大而且為類比控制方式，線路複雜不易維修。現今數位化以成驅動控制器的一般標準，故性能優越且易於數位化之SVPWM以成脈寬調變策略中之主流。而整個系統之控制則全由Altera的晶片組FLEX PF10KA10LC84-4來執行，此種以硬體語言描述之設計方法使設計之時程大幅縮短，並增加了系統設計的維護性及修改性。由實驗之結果證明我們所使用之此種柔性切換電路工作穩定且可靠度佳。

Soft-switching techniques ( zero current switching or zero voltage switching ) applied to power inverter can substantially improve the performances, allowing high frequency operation and minimization of acoustic noise and EMI, reduction of switching losses, limitation of dv/dt and di/dt stress in the power devices .The quasi-resonant dc link soft switching circuit used in this paper needs additional components such as two switches, a diode, an inductor and a capacitor, the two switches are also soft switching, which produces a minimum losses. The quasi-resonant dc link circuit notching the bus voltage and allowing the switches of the inverter just switching at zero voltage. The modulation technique we adapt is Space-Vector PWM and refuse traditional sinusoidal PWM, because the SPWM can't completely utilize the dc link voltage, current ripple is badly and analogical mode control, which is complex and not easy to maintain. Now the digitalization design has become the standard of the drive- controller, so the superior performance and easy-digitized SV-PWM has become major method in the PWM techniques. The control of the system are processed by the chips FLEX PF10KAL10LC C84-4 of Altera company. Whose hardware description language can scrimp the time in design and makes the system more easily to maintain and modify. The experiment results have shown that our soft-switching circuit works very stable and reliably.