Session 2: Energy-Storage Requirements and Solutions for Low-Voltage Hybrids
With the continuous introduction of idle stop/start feature (micro-hybrid) as a standard design in several European and Japanese models, the momentum to increase the commercialization of these vehicles in Asia and elsewhere is intensifying. In Session 2 of AABTAM, automakers presented vehicle development and energy-storage requirements for low-voltage (micro) hybrids, and energy-storage developers presented the latest achievements in meeting the requirements of micro-hybrid architectures.
Tadatoshi Asada is the head of the Engine Electrical Systems Engineering Division at DENSO Corporation in Japan. He joined DENSO in 1988 after graduating from Yokohama National University and in his early years at DENSO was engaged in the development of generator control systems. These days Tadatoshi leads the development and promotion of advanced Start & Stop technology. Last year Tadatoshi's development team successfully launched the world's first mass produced advanced S&S system using a 12V Li-ion battery. This battery permits the elimination of the DC-DC convertor, limiting the system cost whilst improving the fuel economy.
Session Chairman: Heinz-Willi Vassen, Manager Energy and Storage Systems, Audi AG
Mr. Vassen studied electomical engineering at the RWTH Aachen, Germany. In 1997 he became system engineer of engine control at Mannesmann VDO AG. He entered Audi AG in 1999 as diagnostics engineer and became manager of gateway ECU and data buses in 2004. He has been manager of energy and storage systems at Audi since 2006.
Micro-Hybrids Fit for the Future: Requirements for an Additional Battery in the 14V Power Supply Armin Warm, Research Engineer, Ford Aachen GmbH
Micro hybrids are getting higher market shares as they are becoming part of car-maker’s CO2 roadmaps. Micro hybrids are becoming also a standard fit for mainstream powertrains. Based on the potential and limitations of regenerative braking in micro hybrid systems for a conventional battery technology, potential optimizations for micro hybrid systems will be discussed. The focus here is on a dual battery system. The presentation outlines the battery requirements of the second battery and its related use cases.
Mazda ”i-ELOOP” Regeneration Energy-Storage System and Strategy Akitomo Kume, Assistant Manager, Mazda Motor Corporation
Mazda commits to offer significant CO2 emission reduction, Driving pleasure and Environment and Safety to as many cars as possible. To make it possible, Mazda adopted a Building Block Strategy of gradually introducing electric devices such as regenerative braking while thoroughly improving the base technology such as powertrain efficiency improvement and vehicle weight reduction with use of the technology called “SKYACTIV TECHNOLOGY”. As the second step, Mazda introduced i-ELOOP (Intelligent Energy Loop) that recovers deceleration energy with electricity and reuses it to the electrical components of car in 2012. This system is made up of the variable voltage alternator up to 25V for recovering more deceleration energy, the EDLC up to 25V for charging the generated energy and the Step-down DCDC converter for supplying the energy to 12V devices for efficient recovery of kinetic energy. Mazda improves i-ELOOP functionality further for higher fuel economy at a reasonable cost.
The paper will cover:
Aim of i-ELOOP
System design of i-ELOOP
Effects of i-ELOOP
Potential of i-ELOOP for more fuel saving.
12V Energy Recovery System Ryuji Kawase, General Manager, Sanyo Electric Co., Ltd.
Hybrid electric vehicles (HEVs) with a battery system have been expanding the eco-friendly car market thanks to their good economy and performance.
More simplified Idling Start and Stop (ISS) system compared to HEV system can also improve the fuel efficiency with more affordable cost, and is contributing to the expansion of such eco-friendly car market.
For further improvement of the performance, we have developed 12 V energy recovery system using nickel metal hydride (Ni-MH) batteries, and this time the vehicles equipped with the energy recovery system are eventually launched on the market.
The 12 V energy recovery system uses nickel metal hydride (Ni-MH) batteries that are combined in parallel with a main lead-acid battery as sub-batteries.
The parallel connection of the Ni-MH batteries contributes with their better regain characteristics to increase in recovery energy which can be supplied to the electrical components and realization of an extended life of the lead-acid battery by taking in part the role of the main battery.
Toward the next stage, we are examining the feasibilities of hot cranking with sub Ni-MH batteries and of replacing main battery from dedicated lead-acid battery for ISS to lead-acid battery for starting.
We aim to contribute to a better global environment by expanding the eco-friendly car market, as well as spreading this energy recovery system.
Toshiba Lithium-Ion Rechargeable Battery
“SCiB™” Shun Egusa, General Manager, Automotive Systems Division, Social Infrastructure Systems Company, Toshiba Corporation
The low-voltage hybrid vehicle, especially 12V advanced Start & Stop (S&S) system is focused because the fuel consumption is effectively improved by the recuperative energy to be stored in the secondary battery, and the further improvements are expected by adding new functions of coasting, re-cranking and motor-assist. Lithium ion battery with Lithium Titanate (LTO) as the anode is recognized to be the best matched with the these low-voltage hybrid system, and Toshiba is only manufacturer which can mass-produces the LTO-basis battery cells, SCiB™, with high-quality, and has been providing the power type of 3Ah cell to the advanced S&S system from 2012.
In this presentation, the new product lineup and performance of SCiB™ will be introduced for the future vehicle system as follows:
Tuning of cathode materials to match with the voltage requirement of 12V and 14V.
Increase of cell capacity and size to provide the more power
48V System Development for Premium Cars Thomas Weber, Manager Energy and Storage Systems, Volkswagen Group Japan
The continuous increase of functionalities such as comfort, safety, driver assistance, infotainment systems, as well as enhanced innovation, raises the demand on a vehicle's electrical power network. In combination with the electrification of powertrain functions and ancillary units for CO2 reduction, these requirements reach the limit of today's vehicle power supply.
The 48 Volt Power Supply is an extension of the existing 12 Volt Power Net to enable new functionalities in future.
Specifically, this presentation will focus on:
Upcoming electrical innovation
Limitation of 12V power supply
The 48V power supply system approach - Two possible architectures
Specific requirements on energy storage systems for 48V Systems
The Audi iHEV approach
Lithium-Ion Battery Technology for Low-Voltage Hybrids: Present and Future Wonhee Jeong, Senior Manager, Development Center, LG Chem
Lead acid batteries have been the predominant battery technology for conventional 12V vehicle power networks. However, upcoming regulation of CO2 emission and fuel economy draws much attention to low-voltage hybrids based on lithium-ion battery technology, as lithium-ion batteries are lightweight power sources with high recuperation capability. Automotive manufacturers have investigated various 12V and 48V systems with different dimension and performance requirements. Depending on their needs for a pack location and system design, OEMs’ interest in cell chemistry varies from conventional carbonaceous anode-based one to LTO anode-based one to LFP cathode-based one. In this talk, current lithium-ion battery solutions to various low-voltage needs will be discussed with a focus on technical challenges in cell design. Also, we will explore future directions for the development of more cost-effective lithium-ion battery technology.
Lithium-Ion Battery Pack for Stop & Start System Yuki Nagai, Engine Electrical Systems Eng., Division 1, Denso Corporation
Stop & Start(S&S) System using two power supplies, combined with energy regeneration, isan effective technology to reduce CO2 emissions. Lithium-ion battery is an optimal power supply for this system because of its high charge acceptance per weight. We developed the system with low cost and simple structure, which eliminates the DC-DC converter by utilizing a Lithium-ion battery that has voltage characteristics similar to the lead-acid battery. The Lithium-ion battery's range of capacity must be managed appropriately. Therefore, State Of Charge (SOC) detection is very important, and we developed the SOC detection method within the target accuracy. The method adopts the correction system with estimation of OCV during the long time stable electric discharging. It is the characteristic behavior of S&S system.