Charging and discharging cycle design for performance evaluation of HV batteries

The battery greatly influences the performance of the Hybrid Vehicle (HV). So, automobile manufacturers need to evaluate the batteries of various manufacturers and select the most appropriate one. In this case, they need a charge-discharge cycle to evaluate batteries quantitatively. In this paper, we call such a cycle an evaluation pattern and propose a design method of the pattern to evaluate the HV battery quantitatively. HV employs two power sources, motor and engine. In a HV, the appropriate distribution of output torques between the motor and engine is determined based on the driving condition (vehicle speed, acceleration rate, SOC, and so on). That leads to the dependence of the charge-discharge cycle on the driving condition. Therefore, our method divides actual driving data of HV into four driving modes (stopping, acceleration, steady running and deceleration) and then selects a representative pattern for every driving mode effectively by using regression analysis. As a result, we can narrow down the actual driving data that to a few representative patterns. The evaluation pattern is designed by combining the representative patterns. In addition, the quantitative evaluation pattern can be designed in a short time.