# Development of a Hybrid Electric Vehicle Simulation Tool with a Rule-Based Topology
## 3 Results
### HEV Simulation Results
#### 3.1.3 Final Results of the HEV Simulation  
In the final stage, the HEV simulation was run to calculate the pollutants, the SOC, the CO\({}_{2}\) emission and fuel consumption using the selected components under a given driving condition. Figure 10 shows, as an example, the results for the final selection of mode switching for a serial hybrid on WLTC (the different colors represent different modes). For the control system to switch from one transition to another, it had to be possible to define certain  
Figure 9: Energy-weighted operating points of the EM (max. 80 kW) for a serial hybrid on WLTC. conditions with respect to different states, and the logic functions involved were based on the optimal strategy from the GS algorithm. Once the conditions were defined, they were integrated with the other inputs related to the conditions, in order for all these control systems to work together. In this case, the battery capacity was 8.8 kWh, the e-driving range was up to 50 km, and 100 kW of EM and 50 kW of the generator for the serial hybrid. As can be seen, the EV mode (in green) was mainly selected to minimize fuel consumption at low vehicle speeds (early stage of WLTC), and hybrid modes (ICE + GEN mode or ICE + GEN + EV mode) were used on the basis of the SOC values. Figure 11 shows examples of results of vehicle speed, EM speed, EM torque, EM power, and the SOC of serial, parallel and serial/parallel hybrid configurations on WLTC. The battery capacity was 8.8 kWh, which corresponded to an e-driving range up to 50 km and 50 kW of EM for parallel and 100 kW of EM and 50 kW of generator for serial and serial/parallel hybrids. Figure 11: Final results of EM speed, EM torque demand, EM power demand and SOC of serial, parallel and serial/parallel hybrids on WLTC. Figure 10: Final mode switches for a serial hybrid on WLTC. In general, the EMs for serial and serial/parallel hybrids are operated at higher speed with higher efficiency compared to parallel hybrids. However, the EMs for serial hybrids are always in operation during the power demand of the driving cycle. Each hybrid configuration has different optimization methods. In serial hybrids, the EM and ICE with a generator operate independently of each other, with each operating in its most efficient range. The electric driving mode is mostly used at low vehicle speeds to minimize fuel consumption, and the ICE status is determined on the basis of the SOC values. In parallel hybridization, ICE and EM are used in parallel, with mechanical coupling being used to add the torque provided by both sources. Another drawback will be the necessity of a complex mechanical device used to sum the power coming from the ICE and from the EM. The serial/parallel architecture combines the advantages of both aforementioned architectures. This configuration is more complicated, because it involves additional components like mechanical links, and controls and an additional generator. The power splitting device divides the power provided by the ICE into mechanical and electrical paths through a transmission or a planetary gear set. The flexibility of control strategy is a benefit of the configuration, as the ICE and the EM are able to run at their maximum capacity by adapting to the driving conditions. Through the combination of the ICE and the EMs in the HEV simulation, all three hybrid configurations are able to reduce CO2 by up to 30% on WLTC compared to non-hybrid vehicles. The main benefit of hybrids is that the ICE is able to achieve its best efficiency near full load, making operation in this area favorable from a fuel consumption point of view. In case of non-plug-in hybrids, the serial/parallel configuration has some potential with respect to fuel consumption compared to other hybrid configurations. Despite the system complexity of the serial/parallel hybrid, this hybrid has more flexibility in terms of the energy management for SOC and fuel consumption.