During the shifting process of hybrid transmission,the motor plays an important role due to its fast response and accurate torque control.However,it also leads to an excessive reliance on the motor,while neglecting th...During the shifting process of hybrid transmission,the motor plays an important role due to its fast response and accurate torque control.However,it also leads to an excessive reliance on the motor,while neglecting the collaborative control of the motor and clutch.Therefore,there is still room for further improvement in the shifting quality of the hybrid system.In addition,the changing motor torque can easily cause a certain shifting impact at the moment of the clutch state transition,especially for the transition from sliding state to engaged state.In the meanwhile,due to the presence of multiple power sources,the influence of acceleration on the shifting process cannot be ignored.For these problems,this paper proposes a power-on upshifting control strategy for a two-speed series-parallel hybrid transmission,and the root cause of the shifting impact when the clutch slip is eliminated is analyzed.On this basis,a motor torque control method is proposed that is easily to be implemented in engineering,that is,when the target slip is reduced to the threshold Δω_(1),set the motor proportionalintegral(PI)controller output to zero to ensure that the motor output torque can be changed to zero when the clutch slip is eliminated so that the shifting impact here can be suppressed.Then the factors that affect the value setting of Δω_(1) are analyzed based on the dynamics model and verified by simulation and hardware-in-loop(HIL)test based on the control variable method.In addition,the influence of acceleration on the shifting process is analyzed,and corresponding control strategies are proposed to improve the shifting quality.Finally,the Worldwide Harmonized Light Vehicles Test Cycle(WLTC)test is conducted on the vehicle model to compare the shifting control effects under different working conditions,which can verify the proposed effectiveness of the control strategy.展开更多
This paper reports that a 5-cm length birefringent photonic crystal fibre is used to tune the output frequency of unamplified 10-fs Ti：sapphire pulses. The zero dispersion of the fibre is at 823 nm and 800 nm for slo...This paper reports that a 5-cm length birefringent photonic crystal fibre is used to tune the output frequency of unamplified 10-fs Ti：sapphire pulses. The zero dispersion of the fibre is at 823 nm and 800 nm for slow and fast fundamental modes, respectively. It is demonstrated that efficient upshift of the output frequency can be achieved when the pumped radiation is polarized along the slow axis of the fibre. When the average input power reaches 320 mW, about 60% of the output energy is located in one peak at 600 nm and is accompanied by depletion of the pulse inside the anomalous dispersion region.展开更多
基金financially supported by National Natural Science Foundation of China(Grant Number:52172352,52322216)Beijing Natural Science Foundation(Grant Number:L233039)+4 种基金Ningbo Natural Science Foundation(Grant No.2023J052)“Pioneer”and“Leading Goose”R&D Program of Zhejiang(Grant No.2023C01133)Key R&D Program of Ningbo(Grant No.2023Z014)the support of Beijing Key Laboratory for High-efficient Power Transmission and System Control of New Energy Resource Vehiclethe support of the Fundamental Research Funds for the Central Universities.
文摘During the shifting process of hybrid transmission,the motor plays an important role due to its fast response and accurate torque control.However,it also leads to an excessive reliance on the motor,while neglecting the collaborative control of the motor and clutch.Therefore,there is still room for further improvement in the shifting quality of the hybrid system.In addition,the changing motor torque can easily cause a certain shifting impact at the moment of the clutch state transition,especially for the transition from sliding state to engaged state.In the meanwhile,due to the presence of multiple power sources,the influence of acceleration on the shifting process cannot be ignored.For these problems,this paper proposes a power-on upshifting control strategy for a two-speed series-parallel hybrid transmission,and the root cause of the shifting impact when the clutch slip is eliminated is analyzed.On this basis,a motor torque control method is proposed that is easily to be implemented in engineering,that is,when the target slip is reduced to the threshold Δω_(1),set the motor proportionalintegral(PI)controller output to zero to ensure that the motor output torque can be changed to zero when the clutch slip is eliminated so that the shifting impact here can be suppressed.Then the factors that affect the value setting of Δω_(1) are analyzed based on the dynamics model and verified by simulation and hardware-in-loop(HIL)test based on the control variable method.In addition,the influence of acceleration on the shifting process is analyzed,and corresponding control strategies are proposed to improve the shifting quality.Finally,the Worldwide Harmonized Light Vehicles Test Cycle(WLTC)test is conducted on the vehicle model to compare the shifting control effects under different working conditions,which can verify the proposed effectiveness of the control strategy.
基金supported by the National Natural Science Foundation of China(Grant Nos 10874145 and 60490280)the China Postdoctoral Science Foundation(Grant No 20080440014)the Yanshan University Doctor Foundation of China(Grant No B153)
文摘This paper reports that a 5-cm length birefringent photonic crystal fibre is used to tune the output frequency of unamplified 10-fs Ti：sapphire pulses. The zero dispersion of the fibre is at 823 nm and 800 nm for slow and fast fundamental modes, respectively. It is demonstrated that efficient upshift of the output frequency can be achieved when the pumped radiation is polarized along the slow axis of the fibre. When the average input power reaches 320 mW, about 60% of the output energy is located in one peak at 600 nm and is accompanied by depletion of the pulse inside the anomalous dispersion region.
