Fuel Economy Optimal Control of E_REB Based on Discrete Dynamic Programming

For a certain type of Extended-Range Electric Bus(E_REB), by using discrete dynamic programming(DP) algorithm, setting the battery state of charge(SOC) as state variable , seting the baterry power and the engine power as control variables, and taking the fuel economy in complete driving cycle of E_REB as the objective of optimization, then a mathematical model of equivalent fuel economy optimal control and its corresponding DP recursive equation were established. By reasonable and balanced using of the battery power and the engine power, the optimal E_REB `mixed depletion mode´ control strategies were constructed and obtained. In the process of solving DP algorithm, an algorithm of state variable SOC restricting the exploring region was applied which largely reduces the amount of computation, and effectively alleviates the curse of dimensionality in the calculation of the DP. Finally a Matlab /Simulink model is established to verify the obtained strategy and compare its results with those of instantaneous optimal control strategy. The results show that better fuel economy is obtained using globally optimal control on the premise of meeting the the principle of E_REB battery energy depletion.