Abstract
The low mechanical efficiency of metal belt’s continuously variable transmission (CVT) limits its application in new energy vehicles. To further improve CVT efficiency and reduce the energy consumption of electric vehicles (EVs) with CVT, this paper proposes a pure electric CVT configuration and a clamping force control strategy. The slip characteristics of CVT are obtained through a bench test, the dynamic model of CVT slip is established, and a clamping force fuzzy control strategy is designed. The strategy is studied by simulation under extreme conditions and standard driving cycles. The simulation results show that the proposed clamping force control strategy has good adaptability. Under extreme conditions, this strategy can ensure that CVT does not undergo macro slip, while reducing the clamping force by 12.86–21.65%. Energy consumption per 100 km is 14.90 kWh in NEDC, which is 6.67% lower compared with the traditional strategy. CVT average efficiency and average transmission efficiency increased by 3.71% and 6.40%. The research results demonstrate that adjusting the CVT clamping force through fuzzy control based on the slip rate can improve the CVT efficiency and energy economy of EVs, which provides a certain reference for CVT clamping force control strategy development and the application of CVT on EVs.
Highlights
With the intensifying of the energy crisis and environmental pollution, many government departments have formulated increasingly strict regulations to limit vehicle energy consumption and pollutant emissions [1]
This paper presents a pure electric continuously variable transmission (CVT) configuration, and a clamping force fuzzy control strategy based on slip characteristics
It is assumed that the transmission control unit (TCU) can automatically adjust the electric oil pump (EOP) speed according to the system flow demand, realizing the active control of the system flow
Summary
With the intensifying of the energy crisis and environmental pollution, many government departments have formulated increasingly strict regulations to limit vehicle energy consumption and pollutant emissions [1]. Some scholars developed novel multi-speed transmissions for EVs to improve vehicle energy economy [10–12]. Research [21] compared CVT and single-speed transmission through experiments and found that CVT brings a 4.3% reduction in energy consumption for EVs. In addition, some scholars design CVT speed ratio control strategies to improve the transmission system efficiency for EVs [17,22]. Nishizawa et al studied the friction characteristics between the CVT metal belt and the pulley and proposed a friction model and obtained the power transmission state near the macro slip limit [27]. Bonsen et al and Klaassen et al studied the slip characteristics of metal belts by combining theory with experiments They propose a CVT slip model and develop corresponding slip control controllers.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
