HEV application

Abstract

In 1997, Toyota Motor Company launched electric hybrid vehicles into the world market, followed by Nissan and Honda a few years later. They were very popular because of the good fuel economy and the increasing interest in global environmental issue. Therefore, all of the car manufacturers worldwide accelerated their research and development for hybrid electric vehicle (HEV) technology. Although the batteries used for HEV by Toyota and Honda are nickel-metal hydride (Ni-MH) batteries and they are major batteries in the field at present, the pressure for development is put on not Ni-MH but lithium because of the superior characteristics in power, weight, heat generation, and so on to Ni-MH. There are many varieties in HEV technology, for the power partition ratio between the engine and motor is adjustable and dependent only on the design concept. The distinction of the parallel hybrid electric vehicle (P-HEV) and the series hybrid electric vehicle (S-HEV) is a well-known rough classification for HEV: The former is powered mainly by the engine and partially assisted by motor, while the latter is, at any time, powered by the motor connected by the engine through a battery and a generator. As P-HEV is the major technology today, the term HEV will be used instead of P-HEV hereafter in this chapter. There are two types of HEV: High voltage systems of 300-144 V and low voltage system of 42-14 V. The former has a larger power share in power partition in driving than the latter, and the topics here are focused on the former. In the United States, the national project named FreedomCAR for the car technology of high efficiency and low emission by the utilization, for example, of hydrogen fuel is now ongoing. Development of a high-power density battery is one of the development themes in the project. The project is sponsored by the U.S. Department of Energy (DOE) and many national laboratories, universities, and private companies have joined it under the well-organized control of DOE.1 In Japan, a 5-year national project for the development of high-power lithium batteries for fuel cell vehicle application started in 2002. In the following sections, an overview of development status for practical largesized lithium batteries for HEV application will be given briefly. © 2009 Springer Science+Business Media, LLC.