Design And Application Of Lithium-ion Power Battery Test System

With the growing of environmental pollution and energy consumption, the applications of renewable energy increasingly gained people's attention. Power Batteries which have great prospects in renewable energy field are one of the focuses of attention. However, there is a wide variety of Power Batteries and they have different weak points. Existing test methods can not accurately measure the internal characteristics of the power batteries. Therefore, this paper analyzed and compared the power batteries, and the lithium-iron-phosphate battery was chosen to be the experimental subject. To implement the experiment, a Power Batteries test system based on the power converter circuit was designed.The charging and discharging principles and performance parameters of the lithium-ion batteries were analyzed and the main charging strategies were investigated. Because the charging strategies have various kinds of defects, so a multi-level charging method was implemented. The method combined constant current, constant voltage and trickle current charging strategies. The battery discharging strategies was the constant current and pulse-current method. By using these strategies, the parameters of the lithium-ion batteries were tested.There is inconsistency among battery monomers in the process of charging or discharging. So an equalizing protection circuit was presented. The circuit is based on dedicated chips and easy to cascade. It limits the maximum voltage, lowest voltage and maximum current of lithium-ion batteries. With the device mentioned above, battery monomers and battery packs were tested. The charge and discharge curves and parameters were presented. This paper also established an equivalent circuit model of the battery pack and a function of the battery terminal voltage and its'SOC. The function curve coincided with the test results. It verified the correctness of this method.