Fig. 9

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Iterative procedure for solving the problem of optimal battery sizing and control of an EVT PHEV powertrain. For a given power threshold Pth the engine on/off sequence is decided. Then, for a given on/off sequence, the problem in Table 2 is solved assuming a constant vehicle mass. After optimal battery size nb is obtained, the vehicle mass is updated and the problem is solved repeatedly until vehicle mass stops changing. The search for the optimal threshold Pth then continues by repeating the entire process.