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Vol.02 Oct.28,2009 LEAF Technology Hidetoshi Kadota Chief Vehicle Engineer

01 Strengths and Benefits of the Motor and Battery

LEAF Technology Hidetoshi Kadota Chief Vehicle Engineer
What are some of the distinctive traits of riding in an EV?
A motor-driven EV provides a smooth and powerful ride that's completely different from gasoline-driven cars. What makes this possible is a bit difficult to express, but one key is that the motor has the ability to produce maximum torque from zero RPM on up. You get the impression of LEAF's extreme power right from the moment you put it in gear. A standard engine puts out more power as the revolutions rise, and to supply torque at low revolutions requires shifting from gear to gear, either manually or automatically.
An EV, on the other hand, has a single fixed gear ratio that covers the entire range from 0 km/h to maximum speed. It accelerates powerfully, with no delay or jerkiness. And since there's no vibration like there would be with an engine, that smoothness produces a really nice driving sensation.
LEAF Technology Hidetoshi Kadota Chief Vehicle Engineer
The attributes of the motor make for a great ride, don't they?
Yes, but for LEAF that's not all. We also went so far as to figure out what we could do to enhance that pleasant driving sensation. This is the payoff for the long years Nissan has devoted to creating cars with electric motors, including EVs, hybrid cars and fuel-cell cars. More and more, we have come to understand how to control the motor to enhance driving pleasure, and put all of this know-how into LEAF.
LEAF Technology Hidetoshi Kadota Chief Vehicle Engineer
Does Nissan's know-how extend beyond the motors to the batteries?
It does. We began doing R&D into high-performance lithium-ion batteries quite early, in 1992. By 1997 we had them mounted in a model called the Prairie Joy EV , thirty units of which we sold on a trial basis.
The lithium-ion battery is capable of storing a lot of electrical energy, but control technology is essential to utilizing that energy properly in a car. LEAF has a mounted array of 48 battery modules, and controlling them is a major task.
To explain what I mean, let's compare the battery array to a class with 48 students. Each student has individual traits; some kids do their work well, others fall a little short. Once the power demands are set to a certain level, they will be too much for the weaker students and too easy for the capable ones. If you try to match the level to the students, some still won't be able to keep up. Making a single battery with superb performance isn't enough; you've got to have 48 of them working together efficiently to run a car. This is a technology that we have continuously nurtured over the years.
LEAF Technology Hidetoshi Kadota Chief Vehicle Engineer
What are some other attractions that only an EV can offer?
LEAF also handles superbly. When you turn the steering wheel on a curve, you'll be surprised by how cleanly the car maneuvers. That's because we've achieved such a fine balance between the front and the rear. Unlike a car with the engine mounted in front, LEAF's battery is positioned close to the center of the chassis along its entire length. That's why the car is such a virtuoso at maneuvering. Most of the attention is being focused on LEAF's environmental performance, but the ride is invigorating-it feels great when accelerating and on curves.
Vol.01 Oct.21,2009 LEAF Design Masato Inoue Product Chief Designer