Hybrid energy control strategy for hybrid electric drive system in military vehicle

Battery technology is one of the key factors constraining the development of hybrid electric drive technology used in electric combat vehicles (ECV). At present, single energy storage source used widely is very difficult to meet the requirements for both energy and peak power in ECV. By adopting hybrid energy structure to combine high specific power source and high specific energy source, the existing technology can greatly enhance the performance of ECV power supply system. In order to make full use of the advantages of multiple energies the power of hybrid energy sources must be distributed reasonably. Weighting method and filtering method are the main control strategies of hybrid energy with particular focuses respectively, however, without considering the properties of both hybrid energy and engine. According to the characteristics of Ni-MH battery and ultra-capacitor, a strategy is proposed which combines weighting control with filtering control. In this strategy, firstly hybrid energy control modes are subdivided and the switching condition of each mode is determined, and then filtering control is adopted under every specific working mode to distribute the power output of hybrid energy. The results show that the buffer effect of ultra-capacitor has optimized considerably the charging and discharging processes of Ni-MH battery and the peak power of hybrid energy is improved greatly.