BASICS OF ELECTRIC VEHICLE TECHNOLOGY AND A DESIGN STUDY ON A SERIES HYBRID ELECTRIC VEHICLE POWERTRAIN Okan Tur 1 R. Nejat Tuncay 2 Hamdi Ucarol 1 e-mail: okan.tur@mam.gov.tr e-mail: ntuncay@mekatro.com e-mail: hamdi.ucarol@mam.gov.tr 1 TUBITAK Marmara Research Center Energy Institute, 41470 Gebze, Kocaeli, Turkey 2 Mekatro R&D, TUBITAK MRC Technology Free Zone Section B No:18 41470 Gebze, Kocaeli, Turkey Key words: Series hybrid electric vehicle, electric vehicle design, simulation, power management ABSTRACT This paper starts with the basics of electric vehicle technology and introduces design principles of series hybrid electric vehicle. A series hybrid electric vehicle powertrain design study has been presented and a previously developed MATLAB/Simulink model has been used to simulate the designed vehicle in two drive cycles using a soft hybrid energy management strategy. Also performance simulations have been conducted for all electric drive mode and results have been compared with the measurements taken from an experimental vehicle. INTRODUCTION It is known that electric vehicle (EV) technology has been gaining importance at both military and commercial vehicle systems for the last decades. Despite they have higher cost, their higher energy efficiency, lower emissions, regenerative braking and silent mode drive capabilities are major advantages over conventional vehicles. Better performance of electric traction, suitability for future weapon systems, stealth mode, silent watch and reduced signature are some of the reasons for the growing interest on combat electric vehicles. This paper introduces electric vehicle technologies and basic design principals of series hybrid architecture. Performance of the designed vehicle is obtained using previously developed simulation environment. ELECTRIC VEHICLE CONFIGURATIONS Basically electric vehicle configurations can be classified into three groups. They are, • All electric vehicle • Series hybrid electric vehicle • Parallel hybrid electric vehicle As shown in Figure 1, electric energy storage systems such as battery, flywheel and supercapacitor can be used as power supply system in all electric vehicles. In this configuration, the range of the vehicle is limited by the stored electrical energy. Today, this is the most important drawback of EVs as a result of the weight of energy storage systems. M ~ = = = Ultra Capacitor Bank Flywheel = ~ Bi-directional DC/DC Converter Bi-directional DC/DC Converter Battery Pack Motor Driver DC Bus Bar Wheel Wheel Traction Motor Differantial Electrical Connection Mechanical Connection Figure 1. All Electric Vehicle Powertrain Any vehicle having two or more different type of power sources or drive system is called hybrid vehicle. Series hybrid electric vehicle (SHEV) is hybridization of power supply system [2]. At series hybrid configuration, an ICE- generator set is placed additional to all electric system (Figure 2). The generator set (genset) may act as electrical energy storage system state of charge (SOC) controller or as the main power unit. When used as main power supply, it covers average power demands and the energy storage system supplies peak loads. During deceleration or low power drive, energy storage system is charged by regenerative braking or genset. Parallel hybrid electric vehicle (PHEV) is the hybridization of drive system. In parallel hybrid electric vehicles, both ICE and electrical machine can propel the vehicle. For example, at low speeds, electric machine drives the car to use energy more efficiently. For better performance at long distance travels, ICE operates for traction. Electric machine can also act as a generator to charge energy storage systems if torque demand can be supplied by only ICE. One of the parallel-hybrid configurations is shown in Figure 3. Beyond these two different hybrid configurations, as in Toyota Prius example, some other drive concepts have been studied like dual hybrid vehicles, which have properties of both SHEV and PHEV.