## 2 Developed Simulation Model for Different Powertrain Layouts  
In this section, the details of the developed simulation model are presented. Mathematical formulations were developed based on the block diagram that is shown in Figure 1. The model included the drive cycles, an RESC controller, dynamic equations for the vehicle, transmission models, electrical motor maps, and formulations of the subsystems. It should be noted that the RESC controller was only available in the in-wheel motor driven powertrain architecture, and that the developed model was found to be suitable for all the different types of powertrain architectures used for HFCEVs. Based on Figure 1, firstly, the necessary powers and torques for the FTP75 and NEDC drive cycles were calculated, and then, these values were used in the electric motor model. For all types of electric motors, the efficiency was determined from real-life working conditions, and the current and voltage were calculated based on the necessary torque with respect to the angular velocity. After defining the current and voltage of the electrical motor, the energy consumption and recovery were determined based on the proton exchange membrane PEM fuel cell and supercapacitor model. At the end of the calculation, the values for the other parameters, such as the energy consumption, energy recovery, and  
Figure 1: Block diagram of the developed model. operating points on the efficiency maps, were obtained for all the types of powertrain layouts for HFCEVs. In Figure 2, different powertrain layouts and an energy supply diagram for the HFCEV are presented for drawing comparisons between their energy consumption and recovery rates. As shown in Figure 2a, there are four main layouts. The first type of vehicle is equipped with four permanent magnets synchronous with the in-wheel electric motor. In the second, third, and fourth models, there are two main central electric motors, and they are coupled with different types of transmission systems: one-stage (1G) and two-stage gear ratios (2G), continuously variable transmission (CVT), and downsized electric motors with CVT. The speed ratios of the one-stage and two-stage automatic gearboxes were defined by considering the optimum operating conditions of the electric motor with regard to the efficiency map of an electric motor (in the Appendix A). Additionally, the efficiency values of the transmission, system were also considered. Furthermore, an energy supply diagram for the HFCEV is illustrated in Figure 2b. The main energy source of the vehicle is defined as a PEM fuel cell, and its output directly connects to 255 V DC-DC boost converters. A supercapacitor is an auxiliary energy source and serves as the energy recovery unit of the vehicle. Figure 2: (**a**) Vehicle architectures electric vehicles (EV); (**b**) energy supply diagram of hydrogen fuel-cell electric vehicle (HFCEV). The case study vehicle was an urban autonomous passenger car. As shown in Figure 3, the selected vehicle model was shown considering its steering angle, suspension, calculations of resistance forces \(F_{I}\) (aerodynamic drag, tire rolling resistance, and slope), and efficiencies of the mechanical and electrical components. The sum of the load forces that were used are given as follows:  
\[F_{I}=\ p c_{d}A_{f}\frac{\
u\ ^{2}}{2}+m_{t}g\sin(\beta)+m_{t}g\Big{(}f_{0}+f_{1} \
u^{2}\Big{)} \tag{1}\]  
Here,\(\
u\), \(m_{t}\), \(\beta\), \(A_{f}\), \(c_{d}\), and \(\rho\) indicate the velocity of the vehicle, the total mass of the vehicle, the slope angle of the road, the frontal area, the drag coefficient, and the air density, respectively. Note that, total mass of the vehicle is sum of the vehicle mass without transmission layout \(m_{\
u}\) given in Table 1. \(f_{0}\) and \(f_{1}\) are the coefficients of the rolling resistance constants with values that equal 0.015 and 0.0067, respectively. In this study, an autonomous vehicle was chosen to subtract the consideration of driver mistakes and steering response delays in the vehicle.