Date of Award

4-2018

Degree Name

Master of Science in Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Dr. Jennifer Hudson

Second Advisor

Richard Meyer, Ph. D.

Third Advisor

Koorosh Naghshineh, Ph. D.

Keywords

Optimal control, automotive, powertrain, continuous variable transmission (CVT), response log compensation

Access Setting

Masters Thesis-Open Access

Abstract

This thesis is the second part of a two-part study focused on improving Continuous Variable Transmission (CVT) ratio management and control. The objective of the overall project was to develop a methodology for a vehicle with a CVT and a downsized gasoline engine to deliver the maximum vehicle fuel economy within drivability and performance constraints. The first part of this study, as described in [1], focuses on developing a cycle driven model for optimizing the CVT ratio. The study presented in this paper focuses on developing a velocity driven model to simulate the real-time behavior of a vehicle. The results from the optimization schedule presented in backward-looking velocity driven model were utilized to develop a new powertrain optimal operating line (hereafter referred to as P-OOL) which considers powertrain (engine and CVT) efficiency. This P-OOL was created to ensure that the control strategies utilized in the forward- looking model could be used in a real-time vehicle. The proposed P-OOL has been simulated in the model using the Federal Test Procedure (FTP-75) test cycle. Simulation results show that the engine operating points deviate away from the P-OOL. The reasons for deviation of operating points from the P-OOL are vehicle dynamics and powertrain response lag. A control algorithm was simulated which considers powertrain loss and inertia torque due to CVT ratio changes to minimize powertrain response lag. Simulations show a significant improvement in the fuel economy by applying the powertrain response lag compensation algorithm.

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