Nissan Improves Torque, Output of Leaf EV Without Changing Motor

Oct 2, 2017
Tsunenori Tomioka, Nikkei Automotive
The motor and inverter of the new Leaf. In the upper area, there are an in-vehicle charger and DC-DC converter for boosting the voltage of a commercial power source (AC 200V) and charging the battery. In the middle area, there is an inverter. The cross-section is near the cooling area of the power module. In the lower area, there are a motor and speed reducer.
[Click to enlarge image]

The maximum torque and maximum output of the new "Leaf" electric vehicle (EV) are 320N·m and 110kW, respectively, which are higher than those of the previous model of the Leaf (280N·m and 80kW).

However, according to Nissan Motor Co Ltd, which announced the new Leaf Sept 6, 2017, the new model uses the same motor as the previous model. The company increased maximum torque by improving the cooling of the inverter's power module and increased maximum output by making changes to the CPU for controlling the motor and the control method.

To improve the cooling of the power module, Nissan employed a structure that enables to spray water directly on the power module. In the case of the previous model of the Leaf, the power module is located on a plate cooled by water. This time, a hole is made in the plate, and a bar-shaped fin sticks out of the hole. As a result, water can be sprayed directly on the fin.

In regard to the control method, Nissan employed a high-performance CPU for controlling the motor and doubled the amount of calculation. As a result, it became possible to more smoothly rotate the motor. In addition, the control method changes in accordance with the rotation speed of the motor.

"In the case of the previous model, calculation is done to achieve a target value by detecting a current flowing in the motor coil," Nissan said. "However, with the new model, when the rotation speed is high, another element is added so that the motor can operate stably."

Original Japanese article