| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 102 === The aim of this thesis is to develop a new system using battery as energy storage unit for a single-phase power grid paralleled with a power converter for bidirectional power conversion. The system includes a three-arm buck-boost bidirectional dc-dc power converter with a battery module and a single-phase full-bridge dc-ac power converter. The three-arm buck-boost bidirectional power converter, using high-frequency transformers as isolators, can be used to charge and discharge the battery. Moreover, it is three-arm circuit, can be used in high power applications. By using input inductors on the upper arms of the three-arm buck-boost bidirectional dc-dc power converter, making inductor currents work in continuous conducting mode, and implementing pulse-width modulation, one can reduce ripple currents efficiently. In addition, applying digital all-pass filter to estimate the angle of the supply mains voltage, and introducing feedback, one can increase transient response and reduce steady-state error of the single-phase full-bridge dc-ac power converter.
In this thesis, a high performance digital signal processor, TMS320F28069, is used to control the whole system and monitor overall energy usage. Under discharging mode, the battery provides a total output of 500 W to the supply mains, with an overall efficiency of 87%. The three-arm buck-boost bidirectional power converter has a current ripple of 3%, and the single-phase full-bridge dc-ac power converter has a total current harmonic distortion of 9.59%. On the other hand, the battery receives a 500 W input from power grid through constant-current charging operation, The corresponding efficiency is 78%. The three-arm buck-boost bidirectional power converter has a current ripple of 2%, and the single-phase full bridge dc-ac power converter has a total current harmonic distortion of 9.81%. The result confirms the analysis as well as the feasibility of the proposed control strategy.
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