Efficiency improvement of regenerative energy for an EV

Electric Vehicles (EVs) and various Hybrid Electric Vehicles (HEVs) have been attracting a lot of attention for environmental issues and energy crisis. One of advantages of using foregoing vehicles is charging energy by the regenerative brake. The running distance by one electric charge is increased a lot by the regenerative brake. However, the absorbed capacity of the regenerative energy is limited because of the motor capacity and the current limit of the battery. As a result not only the regenerative electric brake but also the mechanical brake must be used. This becomes serious issue in the heavy weight vehicle such as the bus and the truck, the effectiveness of EV/HEV is not obtained. To increase the regenerative energy, the large motor and the battery are requested, however, it is very difficult because of the cost and the limit of the inverter capacity. In this paper, it is verified that the regenerative energy is increased by improving a braking method, averaging the deceleration, without changing the power train system. The proposed method is experimentally evaluated by i-MiEV on the dynamo system, and increases the regenerative energy to 18%.