| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系所 === 99 === The main theme of this thesis is to develop bi-directional converter for battery test of electrical scooter. The proposed system can not only provide constant current and constant voltage to charge the battery but also send energy back to utility to achieve energy saving in the discharge mode. The proposed converter consists of two bi-directional stages, including front end and second stage. The front end is a single-phase AC-DC converter under charging mode operation. It becomes a DC-AC converter as recovering energy. Meanwhile, the front end converter also provides near unity power factor control to achieve better power quality. The second stage is an isolated bidirectional DC-DC converter which simulates the charge and discharge behavior of battery.
The bi-directional DC-DC converter is constructed by two sets of full-bridge circuit, a high frequency transformer, and an LC low pass filter located in front of battery. The DC-DC converter is operated in phase shifted control and an LC filter and a DC-link ripple voltage compensator are added to reduce the current ripple to battery under charging mode. When the converter is under discharging mode, a current-fed full-bridge control is used to send the discharging energy from battery to grid through the DC-AC converter. For improving the current control range under discharging mode, an auxiliary switch is used to achieve 0.1A current control.
In order to facilitate the studies performed in this thesis. A DSP-based converter with necessary peripherals is established to provide 110V/60Hz/single phase input and 1kW/48V output. After establishing the converter, some measured results on Li-ion battery for electrical scooter are provided to show its successful operation and effectiveness.
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