# Dynamic Simulation and Control of a New Parallel Hybrid Power System
## 3 Results and Discussion
### Output Torque and Speed of Power Integration and Distribution Mechanism  
The output torque of the power integration and distribution mechanism is shown in Figure 8a. At the 12 th s, the electric motor provides power to allow the output torque from the mechanism to  
Figure 7: Output (**a**) torque, (**b**) rotational speed of motor, generator, and internal combustion engine. reach 13 Nm until it stops at the 27 th s. At the 51 st s, the electric motor again provides power to increase the torque from the mechanism to 21 Nm until the end of the 90 th s. At the 119 th s, the electric motor again provides power, but is turned off at the 136 th s as it cannot meet the driving demand, and the internal combustion engine is turned on to allow the mechanism torque to reach 25 Nm. At the 162 nd s, the internal combustion engine and generator are turned off, and the electric motor is started to provide a torque of 21 Nm until the 182 nd s. At the 217 th s, the electric motor provides the mechanism torque until it is turned off at the 225 th s. When the electric motor is about to shut down, the internal combustion engine is turned on to provide torque. The generator starts after the internal combustion engine enters the optimal operating region at the 235 th s, so the torque from the mechanism is 25 Nm. At the 252 nd s, the system determines to start the electric motor and turn off the generator. The torque of the mechanism is maintained at 26 Nm until the 309 th s, when the motor is turned off and the generator is started, before it is turned off at the 392 nd s; the mechanism torque during this period is 25 Nm. After that, due to the demand generated by vehicle acceleration, the generator is turned off again while the motor is started to assist the internal combustion engine; the torque of the mechanism returns to 26 Nm. At the 463 rd s, as the vehicle continues to accelerate, the torque demand of the mechanism drops to 24 Nm. At the 515 th s, due to the continuous acceleration of the vehicle, the torque of the mechanism drops further to 22 Nm. After the 541 st s, the vehicle speed begins to decrease, and the torque output of the mechanism fluctuates somewhat under the overall control of the motor, internal combustion engine, and generator, until the vehicle stops after the 570 th s.  
The output rotational speed of the power integration and distribution mechanism is shown in Figure 8b, which is 29 rad/s at the 12 th s and zero at the 27 th s. The output rotational speed of the mechanism at the 51 st s is 49 rad/s until it decelerates to zero at the 90 th s. At the 119 th s, an output rotational speed of 49 rad/s is first provided by the electric motor until it is turned off at the 136 th s, and then, an output speed of 378 rad/s is provided under the operation of the internal combustion engine and the generator. After that, as the vehicle speed drops from 50 to 32 km/h, the mechanism speed is provided by the electric motor alone at the 163 rd s, so the speed becomes 49 rad/s until the electric motor is turned off at the 182 nd s. At the 217 th s, the electric motor provides a mechanism output speed of 49 rad/s until the 225 th s, and then, the internal combustion engine is combined with the generator to provide a mechanism speed of 378 rad/s. As the electric motor is started and the generator is turned off at the 252 nd s, the internal combustion engine and electric motor provide a speed of 441 rad/s until the 309 th s. The motor is turned off after that, and the generator and the internal combustion engine are started to operate until the 392 nd s, and the speed of the mechanism is 378 rad/s during this period. At the 392 nd s, the generator is turned off and the motor is started again. At this time, the electric motor and internal combustion engine provide a mechanism speed of 441 rad/s until the 463 rd s. At the 463 rd s, because the controller judges that the output speed of the mechanism exceeds the demand, the speed is reduced to 430 rad/s.