Development of New 2.0-Liter Plug-in Hybrid System for the Toyota Prius

Reducing vehicle CO2 emissions is an important measure to help address global warming. To reduce CO2 emissions on a global basis, Toyota Motor Corporation is taking a multi-pathway approach that involves the introduction of the optimal powertrains according to the circumstances of each region, including hybrid electric (HEVs) and plug-in hybrid electric vehicles (PHEVs), as well as battery electric vehicles (BEVs). This report describes the development of a new PHEV system for the Toyota Prius. This system features a traction battery pack structure, transaxle, and power control unit (PCU) with boost converter, which were newly developed based on the 2.0-liter HEV system. As a result, the battery capacity was increased by 1.5 times compared to the previous model with almost the same battery pack size. Transmission efficiency was also improved, extending the distance that the Prius can be driven as an EV by 70%. System power was increased by 1.8 times in almost the same size as the previous unit by adopting a double-boost system and increasing the motor output. The same packaging as the HEV system was realized by integrating the DC-DC converter, which is mounted under the rear seat in the RAV4 PHEV, into the PCU in the engine compartment and combining the power supply into the charger. In addition, changing the location of the battery pack from the luggage compartment to under the rear seats helped to realize a low-floor sedan type PHEV with an attractive design. These developments enabled the development of a PHEV with excellent environmental performance and power. The new PHEV achieves an EV range of 45 miles (combined label value) and power of 164 kW.