Model Based Control for a Pressure Control Type CVT Wansik Ryu, Juhyun Nam, Hyunsoo Kim, Sungkyunkwan University Yongjoon Lee, Hyundai Motor Company Dynamic System Design & Control Lab. Sungkyunkwan University

Introduction Flow Control Type Pressure Control Type Pressure control is easier than the flow control in maintaining the desired CVT speed ratio. Pressure control system has an advantage of preventing the belt from slippage in active manner.

Purpose of Study Design a ratio controller for pressure control type CVT Design a model based controller Investigate model based controlled CVT shift performance

Pressure Control Type Ratio Control Valve Solenoid presusre Feed back pressure Spring force

CVT System Dynamics Force equilibrium of the spool motion State equation of the primary pressure where CVT shift dynamics by Ide (1995)

Pressure Characteristics at a Steady State

P-line

Prediction of Shift Performance by P-line Shift speed at B is the fastest among the three points, A, B and C

Prediction of Shift Performance by P-line

Experiments for Ratio Control Performance CVT Test rig

Block Diagram of Ratio Control with PID Control

There exist small response lag in the CVT ratio response Control Performance There exist small response lag in the CVT ratio response

Ratio Response for Stepwise Input of Ps

Steady State Pressure Characteristics with P-line Psol=3.5bar Psol=2.5bar

Model Based Control

Model Based Control

Model Based Control

Conclusion A P-line is proposed from the steady state relationship between the primary pressure and secondary pressure CVT shift performance is predicted using the P-line Linear control algorithm such as PID type controller can be used for the pressure control type CVT A model based control algorithm is proposed The model based control is able to provide improved tracking performance and robustness