Research On The Charging Equalization Of 200Ah Ni-MH Batteries

Battery as the power source of the electric vehicle, in a large part, decides the performance of electric vehicles. However the imbalance of series battery pack in the use of making efficiency and life of battery is reduced greatly. So the battery equalization technology, extend the service life of the battery pack, maintain its capacity, improve the electric vehicle trip range is very important.Ni-MH batteries with high specific energy, suitable for high current charging and discharging, free from contamination and other excellent comprehensive properties, is the first choice for electric bus power supply battery. This paper based on 200 Ah Ni-MH power battery, relying on Zibo electric bus project, according to the analysis in the process of Ni-MH power battery charging gas and composite features, small current sawtooth equalization charging method is proposed. This article main research content is as follows:1. Introduces the equilibrium solution of general classification, and analyzes the common several kinds of balancing solution and their existing problems.2. This paper analyzes the working principle of Ni-MH power battery and its electrical characteristics, according to the analysis in the process of Ni-MH power battery charging gas and composite features, and it provide theoretical foundation for sawtooth equilibrium charging method.3. Analyzed the series of Ni-MH battery power battery equalization method and principle. This article focuses on sawtooth equilibrium principle and equilibrium charging system’s hardware design, according to protection scheme and the modular design thinking, analyzes in detail the system main circuit module, control module, protection circuit module and the main detection module and design the circuit.4. The charge equalization main circuit module adopts three-phase twofold 12 pulse rectifier circuit as the main circuit; Control circuit adopts the way of digital phase shift trigger circuit; Protection circuit include the phase sequence protection of main circuit, over-voltage and over pressure protection of battery pack; Detection module include current detection,voltage detection and temperature detection, real-time monitoring of dynamics of battery pack ensure the safety in the process of charge and discharge.5. Finally for electric buses for field test. In this paper, design of Ni-MH power battery equalization system can achieve very good charge equalization effect by experiment, equilibrium charging system is helpful to extend the service life of the battery and increase the range of the electric bus.