Study on Contactless Balance Charging System for Light Electric Vehicles
| Autor: | Yi-Lin He, 何依霖 |
|---|---|
| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 To reduce the fossil fuel consumption and greenhouse gas emission, the electric vehicle driving by electrical motors has been widely studied for replacing the triditional low efficiency vehicles with internal combustion engines. The major research objective of this dissertation is to study the balancing charging technology for the series-connected battery module which is one of the key technologies in developing the electric vehicle. The techologies of Contactless Power Transfer (CPT) and Charge Equalization (CE) are integrated into the proposed series-connected battery module charger. The convenience and safety would be enhanced with the CPT technology. The lifetime, effective capacity and the maintenance cost of the battery module would therefore be improved with the CE. An improved secondary side converter is first proposed in this dissertation for the CPT with series-parallel compensated contactless transformer. Secondly, the operation principle of the proposed converter is then described to analysis the voltage gain. Thirdly, the zero voltage turned on capability of the acitve switch is achieved to reduce the switching loss. A prototype circuit with 120 V/96 V and 500 W is constructed to verify the proposed converter. The efficiency of proposed converter is 93.7 %(500 W)~96.5 %(100 W). For the charging of the four series-connected battery module, a two-stage Contactless Balance Charger (CBC) is proposed. The first stage is a CPT with a Dual-Output-Winding (DOW) transformer and second-stage is a CE circuit which is a dual-output power converter proposed in this dissertation. For the proposed CE circuit, the operation principle in discontinuous conduction mode is described and the relationship between the switching sequence and the output current is also derived. The charging profiles and corresponding charging modes are also studied. Finally, a CBC is implemented and the efficiency of first stage under 140 W~400 W output power is 92.5 %. The efficiency of second stage under 75 W~300 W output power is about 88 %. In addition, a balancing charging profile for a four batteries series-connected module with 5.5A charging current is carried out. From the experimental results, it can be seen that the voltage of each single battery would not exceed 14.4V. Therefore, the overcharging can be prevented and the validity of the proposed charger is verified. Compared to seried-connected battery module without balancing charging, the dischargeable watt-hour capacity of the balancing charged module is 32.7 Wh which is improved by 4%. The improved effective avaliable capacity of the battery module would therefore make the proposed charger more suitable for the relative applications such as the 48V battery-powerer light electric scooter. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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