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OBD Challenges for Plug In Hybrid Electric Vehicles

2012-01-30
Plug-In Hybrid and Extended Range Electric Vehicle's have quickly become the focus of many OEM's and suppliers. Existing regulations and test procedures did not anticipate this rapid adoption of this new technology, resulting in many product development challenges. The lack of clear requirements is further complicated by CARBs consideration of CO2 inclusion in their next light duty OBD regulation. This presentation provides an overview of the regulatory requirements for OBD systems on hybrid vehicles that intend to certify in California. Near term challenges for EREV?s and PHEV?s are discussed, including concerns with the existing denominator and warm-up cycle calculations. Some proposals are made to address these concerns. Presenter Andrew Zettel, General Motors Company
Technical Paper

Thermal Behavior Study on HEV Air-Cooled Battery Pack

2011-04-12
2011-01-1368
Recently, an increased emphasis has been seen for improving the cooling uniformity and efficiency of HEV battery pack in an effort to increase the battery performance and life. This study examined the effects of geometry changes in cooling systems of battery packs on thermal behavior of battery cells and pressure drop across the battery pack. Initially, a multi-physics battery thermal model was correlated to physical test data. An analytical design of experiments (DOE) approach using Latin-hypercube technique was then developed by integrating the correlated battery thermal model with a commercial optimization code, iSIGHT, and a morphing code, DEP Morpher. The design concepts of battery pack cooling systems were finally identified by performing analytical DOE/optimization studies to estimate the effects of cooling flow and geometries of cooling ducts on the battery temperature variation and pressure drop across the battery pack.
Technical Paper

Voltec Battery Design and Manufacturing

2011-04-12
2011-01-1360
In July 2007, GM announced that it would produce the Chevy Volt, the first high-production volume electric vehicle with extended range capability, by 2010. In January 2009, General Motors announced that the Chevrolet Volt's lithium ion Battery Pack, capable of propelling the Chevy Volt on battery-supplied electric power for up to 40 miles, would be designed and assembled in-house. The T-shaped battery, a subset of the Voltec propulsion system, comprises 288 cells, weighs 190 kg, and is capable of supplying over 16 kWh of energy. Many technical challenges presented themselves to the team, including the liquid thermal management of the battery, the fast battery pack development timeline, and validation of an unproven high-speed assembly process. This paper will first present a general overview of the approach General Motors utilized to bring the various engineering organizations together to design, develop, and manufacture the Volt battery.
Technical Paper

Improving Vehicle-Trailer System Dynamic Stability through Damper Tuning

2011-04-12
2011-01-0978
There are generally two types of directional instability that are associated with a vehicle/trailer combination system. The first is typically referred to as static or divergent instability (jack-knifing), which is a common cause of highway accidents. The second can be called dynamic or oscillatory instability (“snaking” or “fish-tailing”). This type of oscillation occurs due to inherently low system damping at higher speeds [1]. It is sensitive to system parameters and operating conditions and may be excited by various disturbances, such as side wind or abrupt steering inputs. Controlling trailer yaw oscillation can be challenging, especially in markets where small passenger cars are commonly used to tow relatively massive trailers at highway speeds with low hitch loads. This study focuses on the second of the two aforementioned types of instability - dynamic or oscillatory instability.
Technical Paper

High Voltage Power Allocation Management of Hybrid/Electric Vehicles

2011-04-12
2011-01-1022
As the automotive industry moves toward producing more advanced hybrid/electric vehicles, high voltage Rechargeable Energy Storage Systems (RESS) are now being implemented as the main power source of the vehicle, replacing the need for the traditional Internal Combustion Engine (ICE) altogether or just during certain parts of a drive cycle. With this type of architecture, it is becoming a necessity to equip these vehicles with devices that can draw their power from the high voltage (HV) RESS. These HV devices are not only used to support the propulsion of the vehicle but to perform other necessary vehicle functions as well. With demands of high voltage power from multiple systems ranging from RESS thermal conditioning, cabin thermal conditioning, RESS charging, and vehicle propulsion, power demands can exceed the available power of the vehicle. This creates a perplexing problem of how to manage the high voltage power consumption between the different vehicle systems.
Technical Paper

Comprehensive Overview of Human Interface for an Extended Range Electric Vehicle

2011-04-12
2011-01-1023
An Extended Range Electric vehicle brings a wealth of new features since it is capable of driving on battery alone, has a range extending engine, and has a high voltage battery pack that can be recharged by plugging into wall power. The customer is able to interact with the vehicle's plug-in charging system through mobile applications. Along with all these new features is the challenge of designing a driver interface to provide important information to the customer. This paper will describe the unique customer interface features added to the vehicle, and will include some additional specifics related to the hardware used to provide the information.
Technical Paper

Plug-In Charging Feature

2011-04-12
2011-01-1013
As the auto industry becomes more dependent upon Electric Vehicles (Plug-In Hybrid Electric Vehicles, Battery Electric Vehicles, and Extended Range Electric Vehicles), the Plug-In Charging Feature will become an integral part of the driver's daily routine. The Plug-In Charging feature enables off-board electrical power grid (grid based) power to be used immediately or at a later time by on-vehicle functions. The primary use of this grid power is to charge the vehicle's High Voltage (HV) battery, but other uses also do exist. These functions will mainly be active when the vehicle is off.
Technical Paper

Probability of a Crash During Plug-in Charging

2011-04-12
2011-01-1008
Plug-in electric vehicles are becoming increasingly popular as the U.S. and other nations look for ways to reduce the usage of petroleum fuels and reduce the carbon emission footprint. Though plug-in electric vehicles offer many advantages over conventional vehicles, they also present some unique potential hazards due to the presence of high voltage in the vehicle. Specifically, potential high voltage hazards can occur if the electric vehicle is crashed by another vehicle during its plug-in charging session. High voltage hazards include the possibility of electrical shock and thermal events as a result of electrical arcing that can cause injury or death to persons that operate or work around plug-in electric vehicles. Automotive Safety Integrity Level (ISO 26262), often abbreviated as ASIL, is used by the automotive industry for determining the ranking of safety hazards.
Technical Paper

Optimizing Battery Sizing and Vehicle Lightweighting for an Extended Range Electric Vehicle

2011-04-12
2011-01-1078
In designing vehicles with significant electric driving range, optimizing vehicle energy efficiency is a key requirement to maximize the limited energy capacity of the onboard electrochemical energy storage system. A critical factor in vehicle energy efficiency is the vehicle mass. Optimizing mass allows for the possibility of either increasing electric driving range with a constant level of electrochemical energy storage or holding the range constant while reducing the level of energy storage, thus reducing storage cost. In this paper, a methodology is outlined to study the tradeoff between the battery cost savings achieved by vehicle mass reduction for a constant electric driving range and the cost associated with lightweighting a vehicle. This methodology enables informed business decisions about the available engineering options for lightweighting early in the vehicle development process. The methodology was applied to a compact extended-range electric vehicle (EREV) concept.
Technical Paper

Road Map and Technology Trends for Vehicle Engine Cooling Fan Speed Control

2011-04-12
2011-01-1334
This paper describes the rationale for the technology selection and speed control methods for electric cooling fans used for typical automotive applications, including most passenger cars and even some light duty truck s. Previous selection criteria were based primarily around cost, simplicity of implementation and reliability. However, the more recent focus toward fuel economy and optimization of energy consumption at a vehicle level has given a greater priority to the minimization of electrical power draw. Specifically, that need is addressed through both efficiency of the electric motor at any operating condition as well as providing a control method that delivers only the minimum electrical power to meet engine cooling and air conditioning requirements. This paper will explore the various control methods available, their relative merits and shortcomings and how they influence both FTP and real world fuel economy.
Technical Paper

High Voltage Connect Feature

2011-04-12
2011-01-1266
Extended Range Electric Vehicles (EREVs), which are Off board charging capable Electric Vehicles (EV) with an on board charging generator, rely on very complex Rechargeable Energy Storage Systems (RESS) and High Voltage (HV) distribution systems to enable operation as both an EV and an EREV. The connect feature manages the connection and disconnection of a High Voltage (HV) Rechargeable Energy Storage System (RESS) to and from the high voltage components in the vehicle. The RESS is connected to the vehicle's high voltage system to enable vehicle operation. The HV connect feature is a part of occupant, service personnel and first responder safety for all General Motors vehicles that contain high voltage systems. Implementation of the connect feature is the method deployed in GM vehicles to meet high voltage FMVSS requirements.
Technical Paper

Developing the AC17 Efficiency Test for Mobile Air Conditioners

2013-04-08
2013-01-0569
Chrysler, Ford, General Motors, the U.S. Environmental Protection Agency (EPA) and the California Air Resources Board (CARB) have collaborated over the past two years to develop an efficiency test for mobile air conditioner (MAC) systems. Because the effect of efficiency differences between different MAC systems and different technologies is relatively small compared to overall vehicle fuel consumption, quantifying these differences has been challenging. The objective of this program was to develop a single dynamic test procedure that is capable of discerning small efficiency differences, and is generally representative of mobile air conditioner usage in the United States. The test was designed to be conducted in existing test facilities, using existing equipment, and within a sufficiently short time to fit standard test facility scheduling. Representative ambient climate conditions for the U.S. were chosen, as well as other test parameters, and a solar load was included.
Technical Paper

DFMEA and FTA Applied to Complex Hybrid and Fuel Cell Systems

2011-04-12
2011-01-0512
One of the keys to a good reliable design is evaluating potential and past issues, ascertaining and then mitigating the risk that past and future issues will potentially occur. This is even more important with the automobile designs of today and for those in the future, specifically the hybrid and fuel cell vehicle. DFMEA and FTA are tools that aid in the understanding of complex design risks, from the system level down to the component level. This session will look at different case studies (from simple to complex) and the strategies used to understand systemic failure modes using both DFMEA and FTA.
Technical Paper

Radiated Fuel Tank Slosh Noise Simulation

2011-04-12
2011-01-0495
With the introduction of hybrid vehicles and the associated elimination of engine and exhaust masking noises, sounds from other sources is becoming more noticeable. Fuel tank sloshing is one of these sources. Fuel sloshing occurs when a vehicle is accelerated in any direction and can create noise that may be perceived as a quality issue by the customer. To reduce slosh noise, a fuel tank has to be carefully designed. Reduction in slosh noise using test- based methods can be very costly and timely. This paper shows how, using the combination of CFD (Computational Fluid Dynamic), FE (Finite Element) and Acoustic simulation methods, the radiated fuel tank slosh noise performance can be evaluated using CAE methods. Although the de-coupled fluid /structure interaction (FSI) method was used for the examples in this paper, the acoustic simulation method is not limited to the decoupled FSI method.
Technical Paper

Co-Development of Chevy Volt Tire Properties to Balance Performance and Electric Vehicle Range

2011-04-12
2011-01-0096
As an innovative electric vehicle with some new approaches to energy usage and vehicle performance balance, the Chevy Volt required a special relationship between the OEM and tire supplier community. This paper details this relationship and how advanced tools and technology were leveraged between OEM and supplier to achieve tire component and overall vehicle performance results.
Technical Paper

Programmable Charging for Electric Vehicles

2011-04-12
2011-01-0041
With the rising cost of gasoline causing the adoption of the electric car into the lives of average consumers, new avenues of transportation cost control and consumer-vehicle interaction can be explored. Unlike a conventional ICE vehicle where a consumer cannot control the cost of what he or she pays for the fuel source, an electric vehicle provides a means for the consumer to directly impact the price for which they “fill-up”. GM's Programmable Charging feature offers a way for consumers to work directly with the power company to charge their electric vehicles during the most cost efficient hours. The consumer has the option to either start charging when plugging in the vehicle or utilizing the Programmable Charging feature to select a lower cost time to charge their vehicle's battery. Utilizing this feature also benefits the power companies by reducing demand on the Grid during peak usage hours when a customer would typically be charging her vehicle.
Technical Paper

Modeling of Battery Pack Thermal System for a Plug-In Hybrid Electric Vehicle

2011-04-12
2011-01-0666
Fuel economy and stringent emissions requirements have steered the automotive industry to invest in advanced propulsion hybrids, including Plug-in hybrid vehicles (PHEV) and Fuel cell vehicles. The choice of battery technology, its power and thermal management and the overall vehicle energy optimization during different conditions are crucial design considerations for PHEVs and battery electric vehicles (BEV). Current industry focus is on Li-Ion batteries due to their high energy density. However, extreme operating temperatures may impact battery life and performance. Different cooling strategies have been proposed for efficient thermal management of battery systems. This paper discusses the modeling and analysis strategy for a thermally managed Lithium Ion (Li-Ion) battery pack, with coolant as the conditioning medium.
Technical Paper

Voltec Charging System EMC Requirements and Test Methodologies

2011-04-12
2011-01-0742
With the advent of vehicle manufacturer driven on-board charging systems for plug-in and extended range electric vehicles, such as the Chevrolet Volt, important considerations need to be comprehended in both the requirements specified as well as the test methodologies and setups for electromagnetic compatibility (EMC). Typical automotive EMC standards (such as the SAE J551 and SAE J1113 series) that cover 12 volt systems have existed for many years. Additionally, there has been some development in recent years for high voltage EMC for automotive applications. However, on-board charging for vehicles presents yet another challenge in adopting requirements that have typically been in the consumer industry realm and merging those with both the traditional 12 V based system requirements as well as high voltage based systems.
Technical Paper

Analytical Evaluation of Propulsion System Architectures for Future Urban Vehicles

2011-04-12
2011-01-0861
Today, nearly half of the world population lives in urban areas. As the world population continues to migrate to urban areas for increased economic opportunities, addressing personal mobility challenges such as air pollution, Greenhouse Gases (GHGs) and traffic congestion in these regions will become even a greater challenge especially in rapidly growing nations. Road transportation is a major source of air pollution in urban areas causing numerous health concerns. Improvements in automobile technology over the past several decades have resulted in reducing conventional vehicle tailpipe emissions to exceptionally low levels. This transformation has been attained mainly through advancements in engine and transmission technologies and through partial electrification of vehicles. However, the technological advancements made so far alone will not be able to mitigate the issues due to increasing GHGs and air pollution in urban areas.
Technical Paper

Communication Requirements for Plug-In Electric Vehicles

2011-04-12
2011-01-0866
This paper is the second in the series of documents designed to record the progress of a series of SAE documents - SAE J2836™, J2847, J2931, & J2953 - within the Plug-In Electric Vehicle (PEV) Communication Task Force. This follows the initial paper number 2010-01-0837, and continues with the test and modeling of the various PLC types for utility programs described in J2836/1™ & J2847/1. This also extends the communication to an off-board charger, described in J2836/2™ & J2847/2 and includes reverse energy flow described in J2836/3™ and J2847/3. The initial versions of J2836/1™ and J2847/1 were published early 2010. J2847/1 has now been re-opened to include updates from comments from the National Institute of Standards Technology (NIST) Smart Grid Interoperability Panel (SGIP), Smart Grid Architectural Committee (SGAC) and Cyber Security Working Group committee (SCWG).
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