With the continuous introduction of micro-hybrids as a standard design in several European models, the momentum to expand commercialization of these vehicles in Europe is intensifying. In this session, automakers will present vehicle development and energy-storage requirements for micro-hybrids and energy-storage developers will present the latest achievements in meeting the requirements of micro-hybrid architectures.
Session Chairman: Eckhard Karden, Technical Expert, Ford Research Aachen
Dr. Karden is Technical Expert for Battery & Energy Storage Technology at Ford's Corporate Research and Advanced Engineering Centre in Aachen, Germany. Since he joined Ford, he was responsible for numerous projects in the fields of powertrain electrification, battery modeling and monitoring, and storage technology assessment, with a main focus on micro-hybridization in 14V systems.
SESSION AGENDA
Requirements for Next Generation Micro-Hybrid Batteries Eckhard Karden, Technical Expert, Ford Research Aachen GmbH
Abstract
Projections for the penetration of alternative powertrain technologies over the next decades confirm that a large proportion of newly sold vehicles will continue to incorporate an internal combustion engine (ICE), a substantial proportion of which with an ICE as the sole source of propulsion. Micro-Hybrids are part of all carmakers’ European CO2 roadmaps and will soon get high market share as standard fit for mainstream powertrains. They implement two powertrain electrification functions:
engine stop/start primarily during (or just before) vehicle standstill, and perhaps in future vehicle programs also in motion while no acceleration torque is required (rolling stop/start)
regenerative braking by generator control such that electric generation during vehicle deceleration is maximized, and incremental fuel consumption for generating electricity for ancillaries is minimized
Generator and storage system in mainstream microhybrids will continue to operate on the established 14 V standard for at least one more generation of vehicle programs.
Enhanced Flooded lead/acid Batteries (EFB) were developed from standard starter batteries by increasing their shallow-cycling durability and robustness against partial state of charge (PSOC) operation.
Absorptive Glass-fiber Mat lead/acid batteries (AGM) offer greater cycle life than their flooded counterparts and meet the needs of high throughput stop/start systems (e.g. commercial vehicles), vehicles with high and/or deep cycling requirements beyond stop/start (e.g. premium cars with entertainment systems), or low-volume programs where engineering robustness outweighs part cost.
Alternative electrochemical systems like LFP or NiZn offer weight reduction and promise longer service life at significant on-cost, but consistent reliable operation e.g. under winter conditions is yet to be proven, and system integration into 14 V power supply systems a considerable engineering task.
Dual storage systems that combine a robust lead/acid battery with a small “alternative” electrochemical couple offer, at moderate on-cost, the advantages of maximized brake energy recuperation and a redundant energy storage system (e.g. for rolling stop/start) while not compromising on the system reliability provided by the lead/acid battery.
The “alternative” high power:energy storage device, and potentially the generator, may operate at a higher voltage (e.g. 48 V) and then allow to supply certain high-power loads from the same second voltage level. Transition to mild hybridization (propulsion assist) may be smooth.
Illustrative examples of increasing demands regarding Dynamic Charge Acceptance (DCA) will be shown, including test results for various lead/acid based battery technologies.
Close Abstract
Enhanced Flooded Lead-Acid Battery for Micro-Hybrid Vehicles in Japan Masaaki Hosokawa, Manager ISS Battery Development, GS Yuasa International Ltd.
Abstract
Market Trend for Micro-Hybrid As one of the solution to global warming, reducing emission or/and improving fuel consumption has been required for vehicles. As of April, 2012, more than 30 micro-hybrids including idle stop/start system vehicles have been launched in Japan; we estimate the volume would be approximately 30% of total registered vehicles in Japan by 2013. The enhanced flooded batteries for micro-hybrid produced by GS Yuasa have been installed on many vehicles of several automakers. Our products contribute to improve earth environmental in Japan and around the world.
Battery Technology The micro-hybrid requires electric power for cranking including the re-start and electric load during the idling stop. Therefore, high durability performance is required to the lead acid battery. Also, the regenerative charge needs to be much shorter as compared with regular charge, and high charge acceptance is required on the battery. We have improved the durability and the charge acceptance on the battery through optimizing the active material, grid design and electrolyte. As the results, the durability has been 4 times higher, and the charge acceptance has been 3 times higher than that of conventional battery.
Close Abstract
Lead-Acid Batteries in Vehicles with Various 12/14V Start/Stop Technologies Eberhard Meissner, Director Advanced Battery Engineering, Johnson Controls Power Solutions EMEA
Abstract
In the recent 5 years, vehicles compromising start-stop functionality have already gained a significant segment of new passenger cars sold, especially in Europe, the vast majority being successfully powered by AGM batteries. Already by 2015, the majority of new cars may comprise one or the other type of start-stop concepts, combined with further means to reduce CO2 emissions. Also with light commercial vehicles, these systems are introduced more and more.
Millions of start-stop vehicles are running on European roads already, several hundred types of vehicles are offered by the OEMs - all of them powered by lead-acid batteries on a 12/14V level. The majority of these are equipped with sealed AGM-type batteries, known for their excellent cycling performance and stability in characteristics, with electrolyte immobilized in an Absorptive Glass Mat. Other vehicles use enhanced flooded batteries (EFB), conventional designs with free-flowing electrolyte, designed for an enhanced robustness in micro cycling duty.
Regulations to limit CO2 fleet emission drive the development of micro hybrid concepts, which can be realized at moderate cost and therefore easily in a whole fleet. The European regulation, with its fleet targets of 130 gCO2/km for 2015 and of 95 gCO2/km for 2020, is phasing in already in 2012. A key parameter for choosing effective concepts and operating strategies to reduce CO2 emission is the vehicle driving pattern targeted at. The NEDC (New European Driving Cycle) pattern used in European regulations comprises a high portion of standstill periods and therefore drives for engine idling stop when the vehicle is on stand still. More dynamic patterns may reflect the real-world situation better and give room for advanced start-stop operating strategies, including engine stop while the vehicle is in motion. This will require significant changes in architecture including redundant energy supply to secure safe vehicle operations also in case of component failures.
The operating strategy is key for the load duty to the battery, and therefore advanced operating strategies will generate other and additional requirements to battery reliability and predictability. As battery monitoring is essential for any start-stop operation, reliable information about battery status is very critical. Especially a reproducible predictability of battery behavior under duty load patterns from critical devices is an essential criterion for selection of the appropriate types of batteries.
Summary:
Since 5 years, AGM batteries successfully power the start-stop system of millions of vehicles
Start-stop systems are expected to become standard in the next years; new vehicle operating strategies and system architectures will put battery reliability and predictability even more in the focus and guide the decision for the best choice of the battery.
Higher requirements for increased system stability may require an architecture of multiple energy storage devices. Reliably predictable components are essential for energy management.
Close Abstract
An Energy Storage Solution For Next Generation Micro-Hybrid Systems Jeff Phillips, Chief Technology Officer, PowerGenix
Abstract
One of the most economical approaches to improving fuel economy and reducing carbon dioxide emissions in an ICE vehicle is to implement engine shut down when the vehicle is stationary. These stop-start or micro-hybrid systems are becoming ubiquitous and can be serviced by a lead acid battery based solution in many light duty applications. However, substantially improving the benefits of micro-hybrid systems by incorporating regenerative braking, “creep” and “coast” functions places significantly increased demands on the energy storage subsystem. Consequently, there is a need for a low cost, robust energy storage system that can deliver large amounts of cranking power over a wide temperature range, accept high rate recharge, and operate over an extended state of charge range.
This presentation discusses the advantages of the PowerGenix Nickel-Zinc system implemented as a single battery solution capable of absorbing 5C charge rates associated with regenerative braking. SBA test results from 40Ah batteries at 100A and 200A charge rates will be presented to demonstrate the stability of the charge acceptance and the consistency of the cranking voltage over the duration of the tests. Further information will be presented to show the stability and efficiency of the system over a range of temperatures up to 70⁰C. The cold cranking performance (including compliance to EN 50342) will also be described. Lastly, the operational configuration, optimal state of charge and battery management system will be reviewed with supporting data from actual in-vehicle testing.
Close Abstract
Automotive Applications of Double Layer Capacitors (DLC) for Power Net Stabilisation, Boost and Recuperation Considering Lifetime, Temperature and Power Requirements Markus Gilch, Senior Manager Power Net Electronics, Continental Automotive GmbH
Abstract
Double layer capacitors (DLC) have been introduced successfully into the stopp-start technology, boosting the Starter-Generator and stabilizing the power net. First automotive qualification opens a wide field of applications:
Central power net stabilization by serial connection to the battery in the plus or minus path of the battery.
Power net stabilization by dual battery management of a DLC and a battery in parallel
Boosting and recuperation in extended Stopp-Start systems from 12V to 48V micro hybrids.
Availability of Stopp-Start systems can be improved and further potential for CO2-reduction can be achieved.
By the use of DLC, the energy storage systems can be separated: a power source (DLC) for delivering power to the safety relevant high current consumers and an energy source (LiIon, AGM) to keep the power net voltage above the critical thresholds of 6-7V
In this presentation the range of applications and the specific conditions for a safe use in automotive are shown. The combination of a voltage source (battery) and a current source (DLC) allows to react perfectly and on demand to the power needed. Specific characteristics of self discharge and life time will be presented. Since 2010, DLC are in automotive serial use and their proven high reliability and performance contributed to the best rated Stopp-Start system in the market. Further applications in micro hybrid systems will open up new possibilities
Close Abstract
Evaluation of Li-Ion Batteries in 14V Architectures Marc Thele, Technical Coordinator, Vehicle Electrical Energy Management, Audi AG
Abstract
Constantly increasing demands on the electrical power supply in conventional cars lead to the necessity of new supply concepts. The main objectives are:
CO2 reduction
Safety & Comfort
Costs
As an approach, future upper class vehicles are going to be equipped with a new voltage level of 48V – providing a power increase by a factor of 4 to 5 compared to today’s 12V power supply systems. However, the more cost-, weight- and package-sensitive middle class is faced with the mentioned challenges as well. This presentation focuses on different supply concepts without establishing a new voltage level thus reducing the technical measures to a minimum. The following features can be realized by combining robust and reasonably priced lead-acid batteries with small but powerful Li-Ion battery systems:
Improved recuperation of braking power with up to 2 kW
Combustion engine switched off during driving
Comfortable and fast cranking
Maintain all safety arrangements
Close Abstract
Lithium-Ion Advances in Micro-Hybrid Applications Jeff Kessen, Director of Global Automotive Marketing, A123 Systems
Abstract
As the market for micro-hybrid batteries continues to develop, vehicle manufacturers are pursuing a diverse array of system designs with different levels of capability. Although lithium-ion batteries were once thought to be too expensive for this market, advances in both battery design and vehicle requirements offer an opportunity to reconsider the conventional wisdom. This presentation will offer insight into the performance capabilities and economics of applying lithium-ion technology to micro-hybrids.
Vehicle content trends driving new micro-hybrid battery requirements
