MNTRC Newsletter Vol 20, Issue 1: Spring 2013

Battery study will help electric vehicle fleet acceptance

David Klinikowski Director, Center for Bus Research and Testing

Penn State News – Greater efficiencies and wider adoption of an electric vehicle fleet are the goal for a study about battery packs. Researchers hope to develop models that will improve the ability to predict state of health (SOH) and state of charge (SOC), along with improved thermal flow management, in the energy storage systems (ESS) of electric buses and other heavy vehicles. This project will be based on a battery pack consisting of cells that employ lithium titanate chemistry and prismatic shape and that are contained in a fully electric, class 8 passenger bus.

Equipment for creating thermal management model.
Researchers hope to create models for electrical and thermal management.

A battery pack from a bus manufactured by Proterra, Inc., will be studied using the Larson Institute’s environmental chamber and Aerovironment AV900 power processing equipment. The pack will be electrically operated through a simulated drive cycle, and extensive testing will occur in various simulated environments.

Researchers expect an improved model

It will be evaluated for baseline data up to the manufacturer’s limits to characterize its electrical and thermal performance. Then the present battery management system (BMS) algorithms for SOC and SOH will be evaluated for accuracy, and improvements will be designed and validated. In addition, using the baseline data, a lumped node Simulink model of the battery pack’s thermal performance will be developed, assuming liquid cooling. An optimal thermal management system design will be proposed and then validated using computer aided design (CAD) and computational fluid dynamics (CFD) software.

Results will likely be used by heavy vehicle manufacturers as well as battery management system manufacturers as they develop their control systems.

Results will have wide application

The three models produced by the research will have immediate application at the Larson Institute’s Federal Transit Administration sponsored Bus Research and Testing Center in support of the testing and development of battery-powered buses. Through entities conducting energy storage research at Penn State, including the Battery and Energy Storage Technology (BEST) Center and the Graduate Automotive Technology Education (GATE) Center of Excellence: In-Vehicle, High-Power Energy Storage Technology, the proposed work will be applicable to graduate student education in vehicle systems integration and battery management and models.

In addition to distributing the final report through the Mineta National Transit Research Consortium website and the US DOT University Transportation Centers database, the project’s principal investigator, Timothy Cleary, will seek to disseminate the results of this work via publication in journals such as the International Journal of Powertrains and the SAE International Journal of Alternative Powertrains, and presentations at related conferences.

Research to develop prototype bus specs

Low-floor bus.

Advanced low-floor bus designed for long life.

A new research project at Penn State will test nimble, long-life buses that are expected to be in service for up to ten years and 350,000 miles. Investigators plan to identify and quantify the technical characteristics of a new breed of transit bus that is accessible, versatile, reliable, durable, and efficient in all operating environments. It is expected that such a vehicle will help US manufacturers expand their product lines and move into international markets, which in turn will enhance competitiveness and provide opportunities for workforce development and training.

Project partners include Penn State’s Larson Institute; the Florida Department of Transportation; the Federal Transit Administration; and Ride Solutions, Inc., a Florida-based startup company. One goal is to measure the performance and reliability characteristics of the prototype bus in a standard testing environment. The prototype test vehicle, provided by Ride Solutions Inc., is currently undergoing the standard Federal Transit Administration (FTA) Altoona Bus Testing Program evaluation for the 10-year bus, 350,000-mile service life category at the Larson Institute.

Broad-based testing may open new markets

Additional research tests by Larson Institute personnel will further investigate the design’s operational cost efficiencies that affect life-cycle costing. Other goals are to provide opportunities to improve the knowledge base and skills of the bus manufacturing and servicing workforce regarding these buses, and to provide a market analysis for the prototype design that will characterize and document the transit service and operating environment requirements of transit agencies in need of a small, long-life bus.

“This project furthers US Department of Transportation and FTA strategic goals in several areas,” said Dr. Suresh Iyer, the project’s principal investigator at the Larson Institute. “The project will address the state of good repair issues associated with operating cutaway chassis buses on rough roadways. Safety and livability will be advanced through the provision of greater bus accessibility and superior ride quality characteristics.”