# Dynamic Simulation and Control of a New Parallel Hybrid Power System
## 3 Results and Discussion
### Output Torque and Speed of Motor, Generator and Internal Combustion Engine  
The torque output is shown in Figure 7a. At the 12 th s, the electric motor outputs 6.2 Nm to allow the car to move forward until it is turned off at the 26 th s. The electric motor is turned on again at the 50 th s. When the car starts to move at a constant speed at the 57 th s, the torque provided by the electric motor also stabilizes at 11 Nm until it is turned off at the 85 th s. At the 118 th s, the electric motor again provides a torque of 11 Nm until the 136 th s. When the electric motor is about to shut down, the internal combustion engine is turned on to provide 13 Nm torque. When the internal combustion engine enters the preset optimal operating region at the 137 th s, the system starts the generator to assist the internal combustion engine to overcome the output torque changed by various resistances. At the 161 st s, under the system judgment, the internal combustion engine and generator are turned off, and the electric motor is started to provide a torque of 11 Nm until it is turned off at the 182 nd s. The electric motor provides 10 Nm of torque from the 216 th s onward until it is shut off at the 234 th s. Next, the internal combustion engine is turned on to provide 13 Nm of torque, as the road demand exceeds the performance of the electric motor. When the internal combustion engine enters the optimal operating region at the 237 th s, the system starts the generator to assist the internal combustion engine to overcome the output torque changed by various resistances. At the 240 th s, the system determines that the torque demand has increased, so it turns off the generator and starts the electric motor to assist the internal combustion engine to increase the power output. However, when the electric motor starts, it causes the internal combustion engine to briefly jump out of the optimal operating region. This is because the torque output by the electric motor at the beginning has not been stabilized, so there will be a temporary power transmission loss before the output is stabilized. At the 252 nd s, the torque output from the internal combustion engine (13 Nm) and that from the electric motor (13.7 Nm) become similar, and the operation of the mechanism tends to stabilize. At the 308 th s, the vehicle begins to decelerate to 50 km/h; therefore, starting from the 309 th s, the internal combustion engine alone provides 13 Nm of torque. At this time, as the road demand is less than the output power of the internal combustion engine, the generator is turned on until the 391 st s, when it is turned off again. From the 392 nd s, the internal combustion engine alone cannot meet the torque output requirements, and the electric motor is started to provide 13.7 Nm of torque until the 460 th s.  
Figure 6: NEDC2000 high-speed driving pattern. After the 460 th s, the vehicle must accelerate to 100 km/h, and thus, the motor torque is reduced to 12 Nm. After the 510 th s, the vehicle must accelerate again to 120 km/h, and thus, the motor torque is again reduced to 10.4 Nm until the end of the 541 st s. At the 562 nd s, the motor is turned off and the internal combustion engine is running alone. At this time, the generator is started to assist the internal combustion engine until the 567 th s. At this second, the internal combustion engine and generator are turned off, and the electric motor is started to assist the vehicle to slow down to zero speed. The speed output is shown in Figure 7b. The electric motor outputs a rotational speed of 60 rad/s at the 12 th s until it becomes stationary at the 27 th s. At the 51 st s, the electric motor is started. At the 57 th s, the vehicle starts to move at a constant speed, and a steady output speed of 100 rad/s is maintained until the 90 th s, when the electric motor becomes stationary.