Investigation of an ECVT on test bench
- © MDT
The ECVT (Electronic-continuously Variable Transmission) is widely used in HEV (Hybrid Electric Vehicle). Normally an ECVT consists of a planetary gearset and two electric motors. With the help of the ECVT, the vehicle can be driven by combustion engine and electric motors. Hence, the speed of combustion engine can be decoupled to the vehicle speed. The ECVT can increase the driveline efficiency and can reduce fuel consumption.
When the combustion engine is started in a HEV with an ECVT without an attached clutch, the vibration will be transmitted from combustion engine to the vehicle. The passengers feel uncomfortable about this vibration. The current research is focused on comfort improvement by adding a wet clutch between combustion engine and planet carrier. The vibration can be compensated by controlling the wet clutch.
In the cooperation with IAV a physical model of ECVT and a corresponding control strategy will be developed. The physical model includes hydraulic and mechatronic components of ECVT and will be built in the object oriented programming language Modelica with Dymola. Some parameters of this physical model must be identified from measurements on test bench. Firstly, the control strategy should exactly control the piston in the clutch to reach the predefined kiss-point as soon as possible. Secondly, the control strategy should realize an optimized clutch closing process. When clutch closes, the vibration from combustion engine need be reduced and the wear must be minimized.