| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 95 === This thesis is concerned with the design of three-phase expandable parallel multi-functional uninterruptible power supply (UPS) systems. The system communication is conducted by controller area network (CAN). When the AC mains is normal, the proposed system provides compensating reactive power using current-controlled mode. Whereas, if the AC mains fails, the system will supply the battery power to the load with master/slave control. The master UPS operates under voltage-controlled mode, while all the other converters function under current-controlled mode. If the UPS under voltage-controlled mode fails, one of the UPS under current-controlled mode will be changed to voltage-controlled mode to provide stable AC voltage. Thus, each UPS can either provide AC voltage source independently, or be connected with others in parallel for capacity expansion.
The control scheme of the system is implemented by a 16-bit digital signal processor to reduce the hardware components. The experimental results for 1030 W linear resistive load show that the total harmonic distortion of output voltage is 1.32 %. Each UPS can share current and output power evenly.
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