WSEAS TRANSACTIONS on SYSTEMS
3.3 Simulation results
China city drive cycle with maximal driving velocity of 60Km/h and frequent braking situations are selected for simulation (Fig.10). The simulation step is set to one second to enhance the speed of calculation. The initial
energy storage state λ is set to 0.1 and 0.5
with the corresponding rotary speed of flywheel of 5834r/min and 12764r/min.
Some important simulation parameters are stated below: the mass of HEV is 1050Kg; rotary radius of wheel is 0.282m; the frontal area of vehicle is 2m2 and the coefficient of aerodynamic drag is 0.335.
Fig.10 China city drive cycle Fig.11 presents the torque distribution between ICE and ISG as well as the change of
λ and the corresponding rotary speed of
flywheel. It is concluded from Fig.11 that the
variety of λ follows almost absolutely with the
speed of flywheel. So the value of λ is proper to denote the energy storage state of FESS and
the introduction of λ to FESS also makes the
control strategy just similar to that of HEV with chemical battery. Furthermore, the SOC of chemical battery or the charge state of ultra-capacitor is much more difficult to be calculated accurately than the energy storage
state of FESS.
Thus HEV with FESS has
Jianhui He, Guoqiang Ao, Jinsheng Guo, Ziqiang Chen, Lin Yang
propitious to the practical application of hybrid technology. The total operating points of ICE and ISG are presented in Fig.12. The arrows in the figures point to the high efficiency areas. It can be seen from Fig.11~12 that most of the operating points are in the high efficiency areas and meanwhile the required driving torque is also achieved.
(a) The torque distribution between ICE and ISG as well as the change of energy storage state of FESS with initial value of 0.1 are presented in this figure, the rotary speed of flywheel is also shown corresponding to the energy storage state of FESS
Issue 5, Volume 8, May 2009