# Development of a Hybrid Electric Vehicle Simulation Tool with a Rule-Based Topology
## 2 Materials and Methods
### Control Strategies of the Simulation  
#### 2.2.1 HEV Operating Modes  
The control system/supervisor will determine various requests to decide the operating mode of the hybrid vehicle, and these parameters are the key in the control system:  
* Power demand from the EM. - Torque demand from the ICE. * Speed/acceleration of the vehicle. * SOC of the battery. In the control strategy, the tool considers these control parameters as inputs for the system to move for one transition to another over the driving cycle power demand. These values can be modified accordingly to achieve the best results. A rule-based control topology is introduced in this paper, and it determines the transition of variable driving modes on the HEV simulation. The output of the supervisor block is the active drive mode of the vehicle during the given driving cycle. The supervisor is the master controller, and it controls the other subcomponents of the vehicle, such as ICE, power devices, transmission, etc. In total, nine different states are available in the simulation, as shown in Figure 2.  
IDLE mode is the stationary position of the vehicle. This state describes the behavior of the vehicle when not moving, meaning the ICE with generator and the EMs, the two power sources, are at rest. The entire system is at rest, with no generation of power. ICE (GEN) mode is also the stationary position of vehicle. This state describes the behavior of the vehicle when not moving, but the ICE with generator is switched on to charge the battery when the SOC of the battery is depleted. Meanwhile, the electrical machine remains switched off or in a resting position. This state remains active until one of two conditions is met: until the battery reaches a nominal SOC, or until there is a power request from the driving cycle. EV (short for Electric Vehicle) mode is the behavior of the vehicle when there is a power demand from the driving cycle, so the vehicle launches from a state of rest through the power supplied by the battery to the electrical machine, while the ICE and generator remain in the state of rest. This state is only available in HEV or BEV, and is called e-drive mode or battery-only mode; this is the state where only power from a battery is supplied to the EM. When the EM is used as a generator to recuperate this negative power available, and this in turn is used to charge the battery, this is called Braking (GEN) mode. This state also describes the behavior of the vehicle when decelerating. If the braking power is not sufficient to stop the vehicle, it will additionally use mechanical brakes to stop. In ICE + GEN mode and ICE + EM mode cases, the ICE with an EM is mechanically coupled to the wheels to provide power to the vehicle in parallel hybrids. In this state, the excess power generated by the ICE is used to charge the battery (ICE + GEN mode), and the extra power needed is supplied by the battery through EM (ICE + EV mode), in case the power request from the driving cycle is higher than the power from ICE. In serial hybrids, ICE (GEN) mode is active when the power request from the driving cycle is higher than that possible to deliver by battery. Since ICE and the generator are coupled on the same shaft, the power from the generator is delivered to the electrical machine to drive the vehicle. Both the ICE and the generator are run in their most efficient areas. ICE (GEN) + EV mode is the state when the power request from the driving cycle is very high compared to that of which the individual power sources are capable; therefore, a combination of the power sources is used to drive the cycle. The maximum power by the ICE (GEN) is used, and the remaining power that is needed is supplied from the battery. ICE (only) mode is the state in which the vehicle runs like a conventional ICE vehicle. Figure 2: Examples of the different modes for the different HEV architectures. Depending on the hybrid architectures, the used hybrid modes can be represented by 6 or 7 states among the 9 total modes described above.