## 3 Results
### SOFC Powertrain Simulation  
The purpose of this part was to study an electric vehicle using the SOFC technology as a range extender, based on the Nissan e-NV200 van equipped with a 5 kW SOFC stack. The SOFC model was a 5 kW stack using pure hydrogen as fuel. The internal ohmic resistance in the polarisation curve model has been adapted to match the power density of a metal-supported SOFC operating at 550 \({}^{\circ}\)C that was found in the literature. Since the stack reached only 5 kW, the required air mass flow rate was very low. As a result, the compressor that was used in this model was derived from the Aeristech electric supercharger by reducing the compressor and the turbine wheels diameters. The motor-generator model was based on a literature review of a high-speed motor generator for a microturbine [41; 42]. The electric version of the Nissan EV-200N weighed 1685 kg [38], while the vehicle used for the simulations weighed 1740 kg. Concerning the fuel cell system, when it operated at 5 kW, the system efficiency R_(eff,system) reached 67%. The SOFCs stack provided 4.6 kW, and the generator produced 0.4 kW. As seen in Figure 10, the inlet air mass flow was 15.7 g\(\cdot\)s\({}^{-1}\) under 1.48 bar. The total hydrogen mass flow rate was 0.159 g\(\cdot\)s\({}^{-1}\), of which 39% was used in the SOFC stack under 3 bar, and 61% was released into the burner to increase the turbine inlet temperature to 1130 \({}^{\circ}\)C.  
Simulations were conducted through the WLTP driving cycle (described by Figure 6) for an increase in the initial state of charge (SOC) from 10% to 90%. The driving calculation was based on the Nissan SOFC vehicle specifications: the ethanol tank capacity is 30 litres [38]. With a density of 0.789, the ethanol was transformed into 6.2 kg of hydrogen. The first power management strategy tried to find a compromise between hydrogen consumption and driving range. When the operating SOC was between 0-60%, the range extender output power was 3 kW in order to maximise the driving range. From 60% to 80%, the output power was 3 kW; then, the range extender was turned off above 90% to reduce the hydrogen consumption. Figure 9: Comparison between Honda’s data and the model’s data of the operating pressure influence on the output power. As seen in Figure 11, a vehicle equipped with the range extender, a hydrogen tank capacity of 6.2 kg, and an initial SOC of 100%, reached 590 km. This was 236% higher than the pure electric vehicle (driving range for an initial SOC of 100%: 178 km). It must be noticed that when the power management strategy was n\({}^{\circ}\)1, 551 km was driven before the hydrogen tank emptied. With half of the hydrogen tank's capacity and an initial SOC of 100%, the driving range reached 379 km, which was 113% higher than the pure electric vehicle driving range. It was possible to increase the driving range per tank of hydrogen by recharging the vehicle when the SOC was under 60%. With five charge cycles from 60% to 100% every 156 km, the vehicle reached 759 km with only one full tank of hydrogen. Then, it was also possible to increase the driving range with only one charge cycle by using the maximum output power of the range extender all of the time. Previously, the power unit control reduced the power of the range extender from 5 kW to 3 kW when the SOC exceeded the limit of 60% in order to reduce the hydrogen consumption. By keeping the output power at 5 kW enabled the reduction of \(\Delta\)SOC per kilomet. As a result, the driving range was increased by 6.1% compared to the original power management strategy, to reach 626 km. Nevertheless, the driving range per tank of hydrogen decreased by 9.1%, to reach 501 km. Figure 11: Calculated driving range for different initial SOCs and tank capacities. Figure 10: Operating points on the compressor (**left**) and turbine maps (**right**) when the SOFC system operated at 5 kW. According to a Nissan report [43], the driving range of their solid oxide fuel cell vehicle using a 5 kW range extender was 600 km.