## 3 Results and Discussion  
This study used the NEDC2000 driving cycle to confirm the success of the energy management control strategy in an HEV. The initial value, maximum value, and minimum value of the SOC were set to 60, 80, and 40, respectively. Figure 7 shows the simulation result compared to that of the NEDC2000 driving cycle. The solid line indicates the driving speed of the NEDC2000, and the dotted line indicates the output speed. As shown in Figure 7, the motor mode is between 0 and 250 s. From the 250 th s, since the power demand exceeds the maximum power in the motor mode, Mode 2 is used to switch to the ICE mode. At the 253 rd s, it is successfully switched to the ICE mode and controls the generator to adjust the output power. At the 310 th s, the system determines that the power demand is less than the minimum output of the ICE mode, so it switches to Mode 4 to adjust the connection between the internal combustion engine and the generator. At the 313 th s, it is confirmed that the generator is off, so Mode 3, the induction mode, starts the electric motor and connects the power to the ICE. At the 390 th s, Mode 2 is used again to enter the ICE mode from the motor mode. At the 516 th s, the system determines that the required power exceeds the maximum power of the ICE mode, so it directly switches to the dual-power mode. However, considering the actual platform operating conditions, Mode 6 is still added to ensure that the generator is turned off as a protection component system. In the 546 th s, the system determines that the required power is less than the minimum power of the dual power, so Mode 7 is used to switch off the electric motor to the ICE mode. At the 562 nd s, Mode 3 and Mode 4 are used again to return from the internal combustion engine mode to the motor mode. Figure 6: HEV’s operation-mode-switching diagram. Figure 7: Speed map with the NEDC2000 driving cycle. In the proposed energy management control strategy, to avoid the waste of energy caused by the ICE being turned on and off several times, different switching points are set, as explained earlier. At the same time, to make effective use of the characteristics of the integrated motor/generator, different switching points are also set during the switching process between the engine mode and the dual-power mode, as well as switching between the electric motor and the generator. Switching too often may cause the energy being produced and provided to the HEV in an ineffective way. Figure 8 shows the speed of each component in the NEDC2000 driving cycle, from top to bottom: the integrated motor/generator, ICE, power distribution mechanism, eCVT, and wheels. The period of 0-250 s is the electric motor mode, 253-310 s is from the electric motor mode to the ICE mode, and 516-546 is the dual-power mode. When the system is in Mode 1 operation, the EM provides power to the vehicle. After 250 s, the controller determines that the power demand is higher than that of the maximum output of the EM. Therefore, the ICE starts to provide power instead of the EM. During Mode 5, from the 253 rd to the 310 th s, the EM becomes the generator, and a negative value indicates that the generator is in operation. From the 516 th to the 546 th s, Mode 8, with the combination of both the EM and the ICE, simultaneously provides the required power to the vehicle and ensures the optimal operating point of the ICE. Thus, the control strategy contributes to the power demand and fuel efficiency of the HEV. Finally, when a deceleration signal is received, the motor speed decreases gradually and the whole system speed reaches zero. Figure 9 depicts the output torque of each element in the NEDC2000 driving cycle. The output torque of the electric motor and the generator is the external load transmitted back through the power integration distribution mechanism. The ICE can output a stable torque from 250 to 313 s and 390 to 565 s. This is because the external load transmitted from the eCVT to the power integration distribution mechanism is adjusted to a fixed output.