# Concept for Generating Energy Demand in Electric Vehicles with a Model Based Approach
## 4 Simulation and Model Environment
### Vehicle Model
#### 4.1.3. Drivetrain Model  
Generally, three types of drivetrain models are classified. These are dynamic models, stationary models, and quasi-stationary models [34]. Dynamic models rely on the mathematical equations of the motor and the inverter as well as their control and promise an exact representation of dynamic transients as well as a realistic calculation of the motor  
\begin{table}
\begin{tabular}{l c c} \hline \hline  & **Value** & **Unit** \\ \hline
**Nominal Voltage** & 2.7 & V \\
**Capacitance** & 3000 & F \\
**ESR** & 0.29 & m\(\Omega\) \\
**Usable Specific Power** & 5.9 & kW/kg \\
**Specific Energy** & 6.0 & Wh/kg \\
**Stored Energy** & 3.04 & Wh \\
**Operating Temperature** & \(-\)40/65 & \({}^{\text{\tiny{a}}}\)C \\
**range (min./max.)** & \(-\)40/70 & \({}^{\text{\tiny{a}}}\)C \\
**Storage Temperature** & \(-\)40/70 & \({}^{\text{\tiny{a}}}\)C \\
**range (min./max.)** & \(-\)40/70 & \({}^{\text{\tiny{a}}}\)C \\
**Mass (typical)** & 510 & g \\ \hline \hline \end{tabular}
\end{table}
Table 4: Specifications of the Maxwell/BCAP3000 supercapacitor.  
losses. Static models, on the other hand, work in a stationary mode without taking a time constant into account. The control of the motor is not represented in these models and is assumed to be ideal, so the motor torque corresponds directly to the required torque. For each operating point, the motor losses are taken from a static characteristic efficiency map. A compromise of these two modelling approaches is quasi-stationary models. These are essentially stationary models but can also represent the dynamics of the motor. The dynamic behaviour is usually approximated by using a simple \(PT1\) element [34]. The block diagram of the drivetrain model used in this study is shown in Figure 6.  
However, it was also shown that the simulation accuracy of the quasi-steady state of the quasi-stationary model correlates directly with the resolution of the stored efficiency map (see Figure 7). Thus, the larger the step size of the data in the efficiency map, the greater the deviation of the simulated drive losses between the quasi-stationary model and the dynamic model [34].  
In general, the achievable accuracy of the calculation of the energy consumption is closely related to the drive losses. Therefore, even in simple steady-state models, accurate efficiency maps of the individual drive components are required.  
Figure 6: Block diagram of the modeling concept of the quasi-stationary drivetrain model.  
Figure 7: Mean model error with different torque step size of the stored motor map based on [34].  
In this study, 188 torque/speed pairs with their corresponding efficiencies are used based on the efficiency map in Figure 8:  
The analysis and evaluation of existing model concepts has shown that quasi-stationary or steady-state modelling approaches, which use an efficiency map to determine the required/added energy, can be considered state of the art in the field of complete vehicle simulation [34]. Therefore, a quasi-stationary modelling approach is used for the model concept. The efficiency map from Figure 8 serves as the basis of the model. In general, the achievable accuracy of the calculation of the energy consumption is closely related to the power losses. Therefore, even in simple stationary models, precise efficiency maps of the individual powertrain components are required. The Oak Ridge National Laboratory had the motor and the inverter on a motor test bench as part of a benchmark project and recorded the corresponding efficiency maps. This map is used to determine the efficiencies in motor and generator operation in this model.