Development of the control logic for the 42 V HEV system

Due to the increase of electric power payloads in today´s vehicles, the 42 V power system has been considered and is being developed to replace the existing 14 V power system. It significantly improves the problems associated with the alternator and wiring harness because of the increase in the current level. The currently developing 42 V PowerNet system employs a mild-hybrid concept using the ISG (integrated starter and generator). It features the idle stop/start functions and recovers the regenerative energy during braking to improve the fuel economy and to reduce the emission. In this paper, the control logic for the currently developing 42 V system is proposed. Firstly, this work sets the system modeling suitable for the development of the control logic. Secondly, the operation mode (state) that can exist at the vehicle´s operation profile and the transient condition among the states are defined. Thirdly, the energy management strategy applied to the developing vehicle is proposed. Finally, it estimates the fuel economy by simulation when the proposed control logic is applied. The developed control logic is implemented and verified for the experimental HEV system