Battery Power - January/February 2013 - (Page 15)

Advanced Numerical Simulation for Hybrid and Electric Vehicles Engineering the Future of the Auto Industry with Integrated Multiphysics Simulation Software Scott Stanton, Technical Director Sandeep Sovani, Manager of Global Automotive Strategy ANSYS, Inc. With concerns over air pollution and petroleum supplies, the use of hybrid electric vehicles (HEVs) and electric vehicles (EVs) have come to the forefront as alternatives to conventional gasoline and diesel engines. Governments worldwide are promoting HEV/EV research. The US government has announced $2.4 billion in funding for new designs of battery packs, electric motors and other components, setting the goal of 1 million HEVs on the road by the year 20151. The US Department of Energy predicts that by 2030, alternative vehicles will comprise 28 percent of the total US light-duty cars and trucks, a 20 percent increase from 20052. To meet these increased demands for HEV/EV applications, competition is intense to develop improved and cost-effective electric powertrains. The potential payoff is enormous in such development efforts, as are the business risks in going to market with flawed, inadequate or suboptimal designs. Clearly, a revolution is underway in automotive technology. The responsibility for leading the charge has been placed squarely in the hands of automotive engineers, who must completely rethink how they approach powertrain design. For engineers at automakers as well as suppliers of major subsystems and components, the challenge is to conduct a massive amount of research and development on an entirely new generation of powertrain in a highly compressed timeframe. In meeting these demands, leading automotive companies with HEV/EV initiatives are focusing on development efforts driven by simulation rather than outdated methods of trial-anderror prototype testing. Indeed, effective implementation of advanced numerical simulation will likely separate winning organizations from less adept competitors in the race for designing the next generation of improved electric powertrains. Numerous software solutions are available for the diverse types of analysis needed in such development work including mechanical, electrical, electromagnetic, electrochemical, WP 41 fluid and thermal management applications. In general, these separate packages often are not entirely compatible, hampering engineers in efficiently using the full range of technologies in arriving at optimized electric powertrain designs. This article discusses the value of implementing a full range of these technologies as an integrated suite of software operating in a single unified environment. battery packs, electric traction motors/generators and power electronics. The design of these HEV components involves complex physical problems and an enormous amount of challenging system integration. Below, the challenges in development of individual components are discussed as well as relevant considerations of electromagnetics EMC/EMI. Battery Packs Electric batteries in HEV/EVs perform the double duties of providing primary drive power for the vehicle as well as energy for numerous electric-powered auxiliary systems. Therefore, they must meet the same reliability, durability and affordability standards and expectations set by petroleum fuel cars — beyond that, they must provide orders of magnitude more energy than conventional batteries. As engineers design batteries with large energy capacity and greater power output, they must consider the thermal, structural and electromagnetic influences on the battery pack as well as the cells within. For example, batteries generate heat while charging and discharging. The temperature of all cells within the battery pack must be strictly maintained within a few degrees Celsius of each other. Otherwise, harmful internal current loops can form within the pack that drastically shorten battery life. This necessitates a cooling system, whether by air or liquid, and sometimes creates a side challenge of minimizing noise close to the passenger cabin. Drivers of HEV/EVs expect an ultra-quiet driving experience, which is not compatible with a loud cooling system. Engineers must also take into account the physical placement of an electric battery pack within an HEV as well as stresses the battery will experience under a range of driving conditions. The battery must be designed to safely withstand multiple variables such as external heating, over-charging, over-discharging, nail penetration, crush or external short. The same safety goals apply to crash scenarios, in which passengers must be protected from toxic acids released from the battery during such an event. Motor/Generator Today’s automotive engineers are challenged with designing new electric powertrain technologies almost entirely from scratch. Key components included in this task are electric Major Challenges Facing HEV Powertrain Designers For years, automakers invested relatively little time and money in electric machine (that is, the electric traction motor/ generator) design because the internal combustion engine was so widely used. These conventional engines accomplished what they needed to: consumer requirements were met, emissions regulations were not as stringent, and oil prices were not a concern. Today all that has changed, with a huge amount of interest in new motors and a correspondingly huge pressure on companies to develop the most efficient, cost-effective electric design. Brainpower and investment dollars are flowing into this area, and the electric motor, just as with the electric battery pack, poses its own set of design challenges. ANSYS Article Continued on Page 16 January/February 2013 • Battery Power 15

Table of Contents for the Digital Edition of Battery Power - January/February 2013

Battery Power - January/February 2013
Table of Contents
Editor's Choice
GM, ABB Demonstrate Chevrolet Volt Battery Reuse Unit
Testing Requirements in the Electric Vehicle Industry
Nearing the Promise of the Micro-Hybrid Vehicles: Technology Improvements and New Markets
So You’ve Been Placed on Notice... Now What?
Advanced Numerical Simulation for Hybrid and Electric Vehicles
High-Voltage Battery Simulator and Test Systems Critical for Electric and Hybrid Vehicle Development
Key Elements to Assuring a Well Developed Verification Plan for Your Battery Powered Device
New Products
ICs & Semiconductors
Industry News
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Battery Power - January/February 2013