Development of Two-Motor Electric AWD(All Wheel Drive) System for Minivans

Shuhei Tajima･Eigo Sakagami･Hiroki Shimoyama (Nissan Motor)

Nissan Motor has consistently pursued high response, strong, seamless, and high quality driving performance for its electric vehicles. In the development of the electric AWD(All Wheel Drive) until now, the development goal is to make the AWD enjoyable and comfortable to drive by further improving the power and high quality driving of Nissan's electric vehicles not only on snowy roads but also on all road surfaces and situations, by combining the control technology as AWD with the electric drive motor control technology cultivated from the development of electric vehicles, utilizing the merit of 100% electric drive and independent drive of front and rear wheels.
In adopting this AWD system for the first time in a minivan, we developed a minivan with a heavier vehicle weight than a conventional SUV to maintain the strength as an AWD and a sense of security on snowy and rough roads, and to maintain a flat vehicle attitude in which the occupant does not easily get motion sickness even in a minivan with a large change in pitch behavior by optimizing the front-rear driving force with an emphasis on the riding comfort and comfort of the occupant in the rear seat.

High Performance Inverter for an Electric Vehicle with a Newly Developed Double-sided Cooling Power Module

Kazushige Namiki･Kouichi Matsuda (Nissan Motor)･Yuta Numakura･Shuichi Shinohara･Shoya Awamori (Astemo)･Yu Ebihara (Jatco)

This paper describes the specifications of a newly developed inverter system and the features and effects of the technologies adopted. New technologies such as a double-sided cooling power module using thermosetting thermal interface material, a split-arrangement DC bus capacitor, a 3-in-1 structure that shares the housing with the motor and reducer have been used to improve current performance and reduce losses, without increasing mass, compared to the previous model.

Development of EV Powertrain and Battery for the Third Generation LEAF

Sho Maruyama･Kenichiro Gunji･Kazuya Nitta･Masato Nakajima (Nissan Motor)

Nissan was the first in the world to sell the mass-produced electric vehicle "Nissan LEAF“ in 2010 and the second generation was introduced, improving driving range and driving performance in 2017. While EVs have negative aspects compared to petrol and hybrid vehicles regarding driving range and charging time, they provide customers with the unique appeal of EVs through seamless acceleration and quietness, thanks to the characteristics of electric motor. In developing the new third-generation LEAF, we are adopting new development battery systems, a compact integrated electric power unit (3in1), and a bidirectional onboard charger.
To enhance the driving range and charging performance of EV, we are adopting a “Big module” that improves capacity density and charging performance by revising the battery's electrode materials and increasing the efficiency of cell installation. In the development of a compact integrated electric power unit (3in1), we are enhancing rigidity and achieving compactness by sharing the housing for the inverter, motor, and gearbox. This contributes to improvements in NVH performance, realizing unprecedented quietness, while also enhancing efficiency to contribute to the driving range. Additionally, the development of a new bidirectional onboard charger allows the normal charging port not only normal charging but also to provide power supply functionality, achieving appealing features unique to EVs. We would like to report on the details of this technological development.

Study on Slip Ratio Estimation Method for In-Wheel Motor Driven Vehicles Based on Angular Velocity Response to Sensing Torque

TOSHIYUKI AJIMA･Masaru Yamasaki (Astemo)･Wataru Hatsuse (Hitachi)

This paper presents a slip ratio estimation method in which a small-amplitude sensing torque, designed not to affect vehicle speed, is superimposed on the steady driving torque during vehicle operation. The slip ratio is estimated based on the resulting variations in tire angular velocity. The estimation formula is revisited and refined, and the validity of the proposed method is evaluated. Furthermore, the effectiveness of vehicle speed estimation based on the estimated slip ratio is also demonstrated.