Bidirectional Multi-level Converter with Voltage Balance of Batteries

• Main Authors: Wu,Chia-Hsuan, 吳佳軒
• Other Authors: Chen, Liang-Rui
• Format: Others
• Language: zh-TW
• Published: 2016
• Online Access: http://ndltd.ncl.edu.tw/handle/69163926143752161728

博士 === 國立彰化師範大學 === 電機工程學系 === 104 === In this dissertation, a bidirectional multi-level converter with voltage balance of batteries is successfully developed. By combining the battery balancing control and the multi-level converter, bidirectional AC/DC power transmission and battery balancing charging/discharging are achieved without the need of an additional battery balancing circuit. In this dissertation, topologies of commonly used bidirectional multi-level converters are first investigated. Here, the cascaded half bridge multilevel converter is selected because of its smaller number of components and ease of control. The system utilized in this dissertation and its operating principles are then described from the perspective of selective battery balancing control. The system can be operated in rectifier and inverter modes. In the inverter mode, the battery acts as the power source and can produce an AC voltage source at the output with low voltage harmonic to supply the load while achieving balanced discharging. In the rectifier mode, the system can attain a high power factor and allow the battery to store charge while achieving balanced charging. Finally, a 180 W prototype with four battery groups is designed to verify the proposed system. The prototype has three groups of 48/7 Ah batteries acting as normal batteries and a group of 48/5 Ah batteries acting as aging batteries. Experimental results show that when the system is operating in the inverter mode, its available capacity is 20.58% higher and its discharge time is 10.67% longer compared to a system without balance control. When the system is operating in the rectifier mode, its charge capacity is 22.45% higher compared to a system without balance control. The experiment confirms that the system proposed in this dissertation can achieve balanced battery charging and discharging.