|Nissan’s grain boundary diffusion process allows it to reduce the use of dysprosium in the traction motor in the updated LEAF by 40%. Click to enlarge.|
Nissan Motor Co., Ltd. released the updated Nissan LEAF electric vehicle (EV) in Japan. The battery-electric LEAF, now in its second iteration, is now available at Nissan dealers nationwide. With the updates, range at full charge on the JC08 cycle is expected to be 228 km (141 miles)—a 14% improvement over the original version of the LEAF with a 200-km range (124 miles) on the JC08 cycle.
Among the enhancements to the updated LEAF is a newly developed electric motor that will reduce the use of the rare earth element (REE) dysprosium (Dy) by 40% compared to conventional EV motors. The new synchronous AC motor offers the same power output (80 kW) as its predecessor, but less torque: 254 N·m for the new motor, vs. 280 N·m for its predecessor.
In addition to the LEAF, Nissan plans to use the lower dysprosium motor in future hybrid electric vehicles (HEVs).
Using a neodymium-based (NdFeB) magnet, motors used in electric vehicles need to be compact in size with high performance. Dysprosium is added to neodymium magnet’s to strengthen heat resistance. In conventional electric motors, dysprosium is uniformly added to the neodymium magnet, but the new motor—developed in a joint effort with Nissan’s suppliers—features a breakthrough grain boundary diffusion process.
Instead of uniformly adding the dysprosium to the magnets, the new process distributes dysprosium around each crystal grain’s boundary, which improves the magnet’s heat resistance while maintaining high performance levels. The result of this process is a 40% reduction in dysprosium use while still keeping heat-resistance levels comparable with conventional electric motors.
Nissan says this new electric motor is only the first step in the process to limit the use of rare earth elements. The company plans to adopt the grain boundary diffusion process for its hybrid motors, with the goal to ultimately achieve zero usage of dysprosium in other components as well.
With all its the enhancements, the updated LEAF has reduced its power consumption: 114 Wh/km on the JC08 vs. 120 Wh/km earlier. (Battery pack capacity remains the same: 24 kWh.) Other enhancements to the basic LEAF powertrain include:
The high voltage power electronics (inverter and DC/DC converter) and electric motor were integrated, resulting in a 30% volume reduction and a 10% mass reduction.
Weight is reduced by about 80 kg (176 lbs) compared to previous model. This was achieved via the combined powertrain unit, integrated functions, streamlined battery module and case structure, and use of lighter parts.
Driving performance is enhanced by improved steering response in the medium-speed range and optimized suspension characteristics associated with weight reduction. In addition, changes to the regenerative brake control system enable more efficient power generation when the brakes are operated.
Auxiliaries also have reduced power consumption with a heat-pump cabin heater, heated seat for all seats, heated steering wheel and heat shield ceiling.
A long-life charging mode—in which the battery is charged to 80% to extend the battery life—is now available in any charging mode.
The navigation system also provides a “Stop-off charging spot guidance” function, “Power-saving route guidance” function and “Battery capacity at a destination forecast” function which can allay potential range anxiety New ways to search for and locate charging spots easily and quickly. There is also a “Charging spot availability information provision” function, “Quick charger location display” function and “Unavailable charging spot display” function.
At present, there are approximately 400 sales outlets in Japan that are equipped with quick chargers. In order to offer even better convenience and accessibility for LEAF owners, Nissan plans to expand the availability of quick chargers to 700 sales outlets in Japan. When the expansion is completed, one-third of dealers will be able to offer quick charging service.
Since its debut in December 2010, Nissan has sold more than 43,000 units of the LEAF worldwide.