本文旨在發展應用於三相功率轉換器之三相不平衡系統的控制策略， 以作雙向功率之轉換。整體系統架構包含具雙向功率轉換功能之三相交流-直流功率轉換器，可降低市電側之電流總諧波失真率。本文利用數位全通濾波器產生三相落後90度之電壓波形，以計算出市電側之每相電壓峰值及單位弦式波形，同時配合直流鏈電壓與市電側電流閉迴路控制，降低市電電流總諧波失真率。在雙向功率轉換方面，當市電側的功率轉換至直流側，其電壓及電流的相位相同，而當直流側功率轉換至市電側，其電壓與電流相位相差180度，達到高功因的性能。

本文採用32位元數位信號處理器TMS320F28335為系統之控制核心，直流側電壓及電流閉迴路控制軟體皆由C語言完成，可有效減少硬體電路，且提高系統可靠度。利用三相平衡的電壓角位置估測方法，在R相電壓衰減30%時，具功因校正功能，輸出功率為4.0kW，電流總諧波失真為6.31%；具市電併聯功能，輸入功率為3.8kW，電流總諧波失真為6.78%。欲改善不平衡所造成的影響，角位置估測採用數位濾波器，經計算得到三相單位弦式波形進行控制，在R相電壓衰減30%時，具功因校正功能，輸出功率為4.0kW，其效率為90.28%，功率因數約為0.99，電流總諧波失真為2.59%，在R相電壓衰減30%且相位落後30度時，電流總諧波失真為2.93%；在R相電壓衰減30%時，具市電併聯功能，輸入功率為3.8kW，其效率為93.33%，電流總諧波失真為3.40%，在R相電壓衰減30%且相位落後30度時，電流總諧波失真為3.65%。如此，具有明顯改善市電側的電流諧波含量。

This thesis aims to develop a three-phase unbalanced system control strategy that can be applied to three-phase power converters for bidirectional power conversion. The system consists of a three-phase ac-dc power converter which provides bidirectional power conversion that is capable of reducing the current total harmonic distortion. In this thesis, a digital all-pass filter, which enables three-phase voltage waveforms to lag 90 degrees, is adopted so that the peak voltage and unit sine wave of each phase can be calculated. In addition, the total harmonic distortion of the current can be reduced by using closed-loop control strategy of dc bus link voltage and grid current. The voltage and current are in phase when the power is converted from the ac side to the dc side. On the other hand, the voltage and current are out of phase when the power is converted from dc to ac. In conclusion, the system achieves high power factor performance.
This thesis uses a 32-bits digital signal processor, TMS320F28335, as the control core. The voltage and current feedback control strategies have been accomplished by programming with C language which effectively reduces the number of hardware components and improves system reliability. Using the method of three-phase voltage balance can estimate the angular position of the ac voltage. R-phase voltage amplitude is decreased by 30% while the total harmonic distortion of current is 6.31% and the output power with power factor correction is 4.0kW. Besides, R-phase voltage amplitude is decreased by 30% when the total harmonic distortion of current is 6.78% and the input power with grid-connection is 3.8kW. To improve the imbalance effects, the angular position was calculated to obtain the unit waveforms of three-phase sine wave with digital filter for control purposes. The output power with power factor correction is 4.0kW as R-phase voltage amplitude is decreased by 30% and the efficiency is 90.28% with the power factor of 0.99 and total current harmonic distortion of 2.59%. The output power with power factor correction is 4.0kW when R-phase voltage amplitude is decreased by 30% and the phase lag 30 degrees with total current harmonic distortion of 2.93%. The input power with grid-connection is 3.8kW, with R-phase voltage amplitude decreased by 30% and the efficiency of 93.33% with 3.40% total harmonic distortion of the current. Besides, the input power with grid-connection is 3.8kW when R phase voltage amplitude is decreased by 30% and the phase lag 30 degrees with 3.65% total harmonic distortion of current. Thereby improves the current total harmonic distortion significantly.

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