No abstract

The powertrain of electric vehicles in the market has a problem in that its performance degrades because of fluctuations in battery voltage. In order to solve this problem, this paper proposes an energy conversion system to boost a part of the electric vehicle battery voltage. This system consists of the existing electric vehicle powertrain and a bi-directional isolated DC-DC converter called the dual active bridge (DAB). This system is able to compensate for battery voltage drops with high efficiency by using a small capacity DAB converter. In addition, a control method for the DAB converter is proposed. This control method achieves a better response to the transient state than conventional methods. The validity of the proposed system and its control method are confirmed by simulation and experiments. A high efficiency of about 99% is obtained from the experimental system prototype.

This paper shows the transient behavior of a system which boosts a part of the battery voltage for a electric vehicle. This system consists of the powertrain of electric vehicles and a bi-directional isolated DC-DC converter called dual active bridge (DAB). This system can compensate the battery voltage drops with high efficiency compared with the conventional series chopper system. In many studies, the DAB converter operates in the steady state. On the other hand, this paper analyzes the operation of the DAB converter in the transient state. Especially, the operation at the start of the DAB converter is focused on.