Page - 119 - in Hybrid Electric Vehicles

rpm. At the start of the combustion engine process, ICE is accelerated to the idle speed, where it is maintained by the electronic control unit. The entire process of starting the engine (in normal condition), from the beginning until stable operation at idle speed, lasts 0.8 s. In the winter, this process may take 1.5 s. The speed profile of starting the ICE is presented in Figure 11. For the alternator mode, the nominal value of the electrical loads is considered in the model. Some electrical loads are intermittently connected (fan, electrical window, heating systems, etc.). Other loads are dependent on ICE speed (fuel pump and injectors) or the speed of the vehicle. When the entire driving cycle is considered, the fuel consumption in the vehicle is reduced to 878.63 ml for the BSAB system and 941 ml for the ISAB system. These values represent a fuel economy of around 16% for BSAB and 17.3% for ISAB of total consumption compared with a classical vehicle with a dedicated alternator and starter (without booster option) system. The difference in fuel consumption is due to the value of nominal power of electrical machines (see Table 1). But, the performances of SynRM are limited by the battery (which uses 75 Ah) capacities. If it uses a stronger battery, the total fuel economy can be increased with 2 or 4% (especially due to the booster mode). In the mechanical evaluation of electrical machines for automotive applications, the varia- tion of electromagnetic torque is one of the most important parameters, because this varia- tion (torque ripple) can become a source of noise and vibration in vehicles. Thus, for a better visualization of the torque profile of PMSMOR and SynRM, a new scenario for all three regimes was considered. For better comparative results (variation of axis torque) between IASB and BSAB, the BSAB system is taken into account through directly coupling (using ratio 1:1 between ICE and BSAB speed) at ICE. The starter and generator regime has been set for 1.5 and 20 s, respectively. The variation of the axis torque in the generator mode has been obtained by intermittent connection of the electrical loads (lights, HVAC, media, etc.). For the booster mode, the speed of the vehicle is increased from 70 to 120 km/h in 17 s, necessary to overtake other vehicles. In this case, the battery is considered fully charged. Figures 12 and 13 show the variation of the axis torque versus time for all operating modes, respectively. Due to the proper windings-slot combination, the torque ripple values are below Figure 11. Speed profile at starting ICE. Performance Analysis of an Integrated Starter-Alternator-Booster for Hybrid Electric Vehicles http://dx.doi.org/10.5772/intechopen.68861 119