Design of a Single Axle Regenerative Brake System for a 2005 Thru-the-Road Hybrid Electric Chevrolet Equinox

The University of Tennessee through its mechanical engineering department is participating in an advanced vehicle design competition, Challenge X, sponsored by the Department of Energy and General Motors. Participants are challenged with redesigning a 2005 Chevrolet Equinox that will minimize energy consumption and reduce emissions while maintaining the stock performance, safety, and utility of the vehicle. The overall vehicle architecture and control system for Tennessee's vehicle entry is described while focus is given to the design of the single axle series regenerative braking system. A series regenerative braking system provides a means of capturing the kinetic energy otherwise lost in the form of heat using conventional hydraulic/friction brakes found in the stock vehicle. The purpose of this thesis is to describe the system design and operation of a tunable single axle regenerative brake system for use in the Challenge X vehicle. A dual stage brake pedal will allow the regenerative system to work in conjunction with the conventional system to provide the braking required to safely stop the vehicle. A system controller will interpret driver input through the brake pedal and vehicle status to determine how to proportion the energy during a braking event. The system is designed to operate "transparent to the driver." The driver should experience the same pedal feel and vehicle performance as with the stock system. Therefore, the system will require calibration to achieve optimal energy conversion and drive quality metrics. The control algorithm for the regenerative brake system is tested using the Powertrain System Analysis Toolkit (PSAT) [12]. A comparison between parallel and series brake strategies is made, showing the benefits of using the series regenerative brake system.