ABSTRACT This paper describes a newly developed electrified powertrain that incorporates various energy-saving improvements and is intended for use on a 2013 model year EV. Based on a 2011 model year EV that was specifically designed and engineered as a mass-produced EV, this powertrain integrates the traction motor, inverter and charging unit to achieve a smaller, lighter package for expanding application to more vehicles. Integration of the motor and inverter in particular reduced the part count for enhanced assembly ease, in addition to reducing heat transfer, noise and vibration. The specific features described in the paper are the three points below. Improving the layout of the inverter parts in order to downsize and integrate the inverter with the motor. Reducing the transfer of heat from the motor to the inverter. Reducing the excitation forces of the motor and optimizing the inverter for noise and vibration. 1. INTRODUCTION Two years ago in December 2010 the Nissan LEAF was released as an electric vehicle (EV) that was specifically designed for mass production.[ 1] The specifications and performance of the motor and inverter were optimized for use on the LEAF, enabling the vehicle to provide the pleasing driving performance and acceleration that characterize EVs. [2][3] The electrified powertrain of the 2011 model year LEAF has been highly acclaimed in many quarters for its impressive power performance. In 2011, it became the first electrified powertrain ever to be named to Ward's 10 Best Engines list.A new electrified powertrain has recently been developed for the 2013 model year LEAF, based on the unit used on the 2011 model. This new powertrain integrates the motor, inverter, reducer and power delivery module (PDM) into a smaller and lighter package for the purpose of expanding application to a wider range of vehicle models. This paper describes the features of this new electrified powertrain, focusing in particular on the technical and structural details involved in integrating the motor and inverter. 2. SYSTEM OVERVIEW An investigation was undertaken in the initial stage of development with the aim of optimizing the overall layout of the electrified powertrain system. The results revealed that integrating the motor, inverter, PDM and other components located at different places in the vehicle would make it possible to reduce the number of high-voltage harnesses and connectors and cooling water circulation pumps needed between components, as shown in Figures 1 and 2. An investigation was then conducted to examine how the components should be laid out in order to facilitate optimal integration. Various methods have been considered for integrating the motor and inverter, and the related structures of three typical proposals are outlined in Table 1. Development of an Integrated Electrified Powertrain for a Newly Developed Electric Vehicle2013-01-1759 Published 04/08/2013 Hirofumi Shimizu, Takahito Okubo, Izuho Hirano, Shigeaki Ishikawa and Makoto Abe Nissan Copyright © 2013 SAE International doi:10.4271/2013-01-1759Downloaded from SAE International by Tsinghua University, Monday, June 03, 2019Figure 1. Reduction of high-voltage wiring harnesses and connectors through layout changes Figure 2. Shorter cooling water circuit and fewer water pumps In deciding which integration method is best, it is also necessary to consider productivity, safety and other factors in addition to the performance requirements, vehicle size, electrified powertrain size and in-vehicle layout. In this project, we intended to install an 80-kW electrified powertrain in a C-segment size vehicle. After considering the relative advantages and disadvantages of each proposed method, we decided to adopt pattern #2 with the inverter positioned on top of the motor.Table 1. Patterns for integrating the motor and inverter Downloaded from SAE International by Tsinghua University, Monday, June 03, 2019In designing the actual system layout, the various