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Control of a CVT in a Flywheel Assisted Driveline
Technical Paper
2000-05-0132
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English
Abstract
Hydraulic control of a Continuously Variable Transmission (CVT) is the focus of this paper. This CVT is part of a driveline, which incorporates a compact flywheel assisting the engine in high-speed transients. Controlling the CVT boils down to realizing desired gear ratios at maximum transmission efficiency, while preventing belt slip. These wishes are conflicting in that maximizing efficiency is performed by minimizing operating pressures, while preventing belt slip for all-partly unpredictable-situations calls for a safety margin in the applied pressures. Preferably, outputs-to-be-regulated would be the gear ratio and some quantity representing the margin for belt slip. Because of the highly nonlinear behaviour of the CVT and its hydraulic actuation circuit (valve saturations, nonlinear differential equations, etc.) it seems useful to consider nonlinear control theory. In the implementation, severe model uncertainties suggested to incorporate a less model-based controller. The resulting compensator is a cascade of two SISO PI pressure controllers, and a model based feed forward for the pressure set points. The feed forward is determined from the desired speed ratio, and constrained by the belt slip criterion besides operational limits. The controller design is experimentally validated at a 78 [kW] test stand, showing promising results.
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Authors
- B.G. Vroemen - Eindhoven University of Technology Fac. of Mechanical Engineering, Section Systems & Control P.O. Box 513, 5600 MB Eindhoven, The Netherlands
- F.E. Veldpaus - Eindhoven University of Technology Fac. of Mechanical Engineering, Section Systems & Control P.O. Box 513, 5600 MB Eindhoven, The Netherlands
Citation
Vroemen, B. and Veldpaus, F., "Control of a CVT in a Flywheel Assisted Driveline," SAE Technical Paper 2000-05-0132, 2000.Also In
References
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- Druten, R.M. van, et al “Design and construction aspects of a Zero Inertia CVT for passenger cars,” FISITA World Automotive Congress Seoul 2000
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- Rundqwist, L. “Anti-reset windup for PID controllers,” PhD thesis TRFT-1033 Department of Automatic Control, Lund Institute of Technology Lund, Sweden 1991
- Serrarens, A.F.A. Veldpaus, F.E. “New concepts for control of power transients in flywheel assisted drivelines with CVT,” FISITA World Automotive Congress Seoul 2000