本文旨在研製線上型三相不斷電系統。於市電正常供電時，由三相功因校正器穩定直流匯流排電壓，同時提供電能給昇/降壓型轉換器對蓄電池充電，並由三相三臂式換流器對負載側提供三相平衡之低諧波失真之電壓波型；於市電中斷時，依據負載所需功率，由昇/降壓型轉換器傳送蓄電池能量至直流匯流排，使三相換流器能持續對負載供電。在市電側之三相功因校正器方面，採用直流電壓閉迴路控制，以穩定直流匯流排電壓，即使負載側供給三相不平衡或非線性負載，仍可平衡的供電，且輸入電流之諧波含量低、輸入功率因數接近1.0。蓄電池的能量管理方面，則採用昇/降壓型轉換器作放電及充電控制，放電以定電壓控制，充電則採二段式定電流-定電壓方式。在負載側之三相換流器方面，採用電壓閉迴路控制策略配合岛-Z變壓器，將三相之各相電壓分別控制，產生出每相獨立之命令，以達到在不平衡且非線性之負載時，具有能輸出三相平衡電壓之性能。
本文採用32位元數位信號處理器(DSP，TMS320F28335)為系統之控制核心，且回授電壓及電流，以軟體完成閉迴路控制，減少硬體電路。
本系統已完成3kW之線性負載供電測試，負載端的相電壓諧波失真率
0.82%；另外，在2kW之不平衡負載供電測試，負載端的相電壓諧波失真率為1.55%；且於在2kW之非線性負載供電測試，負載端的相電壓諧波失真率為4.41%；本文不斷電系統工作於市電正常時之系統效率為84.3%，於市電中斷時之系統效率為87.4%，最後實驗結果證明本系統之可行性，並且達到規範之標準。

This thesis is concerned with the implementation of on-line three-phase uninterruptible power supply systems. When the AC mains is normal, the three-phase power factor corrector converts the mains voltages into a constant DC and also provides boost/buck converter standalone charge to the battery bank. Then, a three-phase three-leg power inverter creates balanced three-phase sinusoidal voltages with low harmonic distortion across the load terminals. If the AC mains fails, the system will supply the battery power to the load under the discharge mode. In the three-phase power factor corrector, a DC voltage closed-loop control which stabilizes the DC voltage is adopted to maintain the balance of the utility source and make the input power factor close to unity with low current harmonics. As to the management of battery bank, the charging/discharging schemes are fulfilled by the boost/buck converter. While in the three-phase power inverter, a AC voltage closed-loop control is adopted to facilitate the independent control of voltage for balanced, unbalanced as well as nonlinear loads.
The control scheme of the system is implemented by a 32-bit digital signal processor(DSP, TMS320F28335) to reduce the hardware components.
The experimental results for 3 kW balanced liner resistive load, 2 kW unbalanced resistive load and 2 kW nonlinear load show that the total harmonic distortions of output are 0.82%, 1.55% and 4.41%, respectively. It is seen that the efficiency of UPS is 84.3% and 87.4% can be achieved for AC normal and AC off operation modes respectively. In conclusion, the experimental results demonstrate that the controller successfully achieves the steady-state RMS voltage regulation specification as well as the total harmonic distortion and the dynamic response requirements of major UPS standards.

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