“…In this study, a five-order polynomial equation is employed to simulate the relationship between the fuel rate efficiency and engine A five-order polynomial equation is employed to simulate the relationship between the motor efficiency and motor power in the driving mode, as: (20) where the fitting coefficients k 1 to k 5 , solved by the least square method, equal −1.967e −06 , 1.21e −04 , −0.002862, 0.02551 and 0.7049, respectively. The Gaussian function is employed to illustrate the relationship between the motor efficiency and motor power in the regeneration mode, as: (21) in which the fitting coefficients a 1 , a 2 , b 1 , b 2 , c 1 and c 2 , equal 2.342, 9.688, 19.76, -3154, 12.52 and 2191, respectively.…”