Development of Electric Vehicle System for City Commuter Vehicle

Recently, automakers have launched various types of electric vehicles (EVs) to help reduce global CO₂ emissions and reduce dependency on fossil fuel energy. Because the lithium-ion batteries that are currently under development are restricted by energy density, the physical size and mass of the battery must be significantly increased to extend the cruising range of the EV. Furthermore, dedicated charging infrastructure is required to charge the battery in a short time. At SAE in 2012, Toyota Motor Corporation proposed a concept that described the EV as suitable mainly for short-distance transportation now and in the near future. Later in the same year, Toyota launched a new EV that embodies this concept in the American and Japanese markets. This new EV is light-weight and has a compact body size, and its battery capacity is designed to sufficiently cover distances traveled in daily life. Charging is assumed to take place mainly at home. To maximize the performance of the lithium-ion battery, the condition of each battery cell is directly monitored on a constant basis, and each cell is reliably protected. Moreover, the key controls as well as the on-board charger and other main components (such as the motor and inverter) are based on advanced technology developed for hybrid vehicles (HVs). As a result, a highly reliable system was developed with an extremely high level of electricity consumption efficiency. This paper describes this EV system that has been developed for use in urban areas.