| The current status and the development of Electric Vehicle and power battery are introduced. As the core of Electric Vehicle, power battery should have high power output level and long life. The value of peak power under different conditions must be considered when battery management system and Electric Vehicle are designed. The methods of two- pulse discharge, multi- pulse discharge and constant power discharge are selected to evaluate the maximum output power at 10s of rectangular Ni/MH battery with capacity of 6Ah which is employed on HEV, with reference of the measurement criterion of battery power. The measurement of two -pulse discharge and multi- pulse discharge are used to evaluate the power characteristics of battery and the method of constant power discharge is used for the confirmation purpose of the evaluation results. The main conclusions are as follows:1.The difference of the battery power can be reflected by the test of two pulse discharge, but the value of the test is larger than the actual value of the battery power.2. The maximum output power can be calculated by the function of voltage versus current which is plotted by the measurement of multi-pulse discharge. The relationship between voltage and current of the battery is evaluated by data fitting of one order function, two order function and exponential function. The difference of the battery power can be reflected by one order function, but the value of the test is smaller than the actual one; the characteristics of current and voltage cannot be estimated by two order function; the value of the battery power which is calculated by exponential function can match the result of constant power discharge well.3. The method of constant power discharge is a way by changing the power value step by step and proceeds discharge until the power output can only last for less than 10 seconds at a certain value. The method can offer accurate result but the process is complicated, also the requirement for the equipment is high. |
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