Tham khảo tài liệu 'electric vehicles modelling and simulations part 11', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Multiobjective Optimal Design of an Inverter Fed Axial Flux Permanent Magnet In-Wheel Motor for Electric Vehicles 289 Fr fMvg 1 Fa v vw 2 2 Fc Mvg sin a 3 where fr is the rolling resistance coefficient which is an empirical coefficient depending on the road-tire friction Mv is the mass of the vehicle g is the earth gravity acceleration p is the air density Af is the frontal area of the vehicle CD is the coefficient of aerodynamic resistance that characterizes the shape of the vehicle v is the vehicle speed vw is the component of the wind speed on the vehicle s moving direction and a is the road angle deduced from the road slope . According to Newton s second law the total tractive effort Ft required to reach the desired acceleration a and to overcome the road load is Ft Mva Fr Fa Fc. 4 Once the total tractive effort is computed the total torque Ft and power Pt required to be produced by the four in-wheel motors can be expressed as Tt F wheei 5 Pt Awheel 6 where rwheel is the drive wheels radius and ữwheel is the rotational wheels speed. Based on the specifications of an urban EV Ehsani et al. 2005 summarized in Table 1 and on the above-described EV traction system the requirements of one in-wheel motor can be easily computed. All the results are presented in Table 2. Note that in addition to provide its requirements the in-wheel motor must also respect some constraints. The main constraints are the total weight of each of the four in-wheel motors Mmotor imposed by the maximal authorized unsprung wheel weight and the imposed outer radius Rout of the motor imposed by the rim of the wheel . Those are also specified in Table I and Table 2. Weight Mv 1150 kg Max. speed Vmax m s 50 km h Acceleration a 1 m s2 Frontal area Af m2 Coefficient of aerodynamic resistance CD Rolling resistance coefficient fr Max. road angle a 10 Rim diameter 14 Number of in-wheel motors 4 Table 1. Specifications of an EV 290 Electric Vehicles - Modelling and .
