This paper describes a newly developed motor and inverter system with maximum torque of 320 Nm and maximum power of 110 kW for a 2018 model year EV. The system achieves this performance with no increase in size from the previous 2013 model year system with maximum torque of 254 Nm and maximum power of 80 kW.
The specific features of the new system described in this paper are summarized below.
A new inverter power module that adopts a direct cooling structure produces higher current density than the previous model. The designs of components experiencing structural and electrical variation that affects heat generation by the power semiconductors were confirmed. Furthermore, the motor temperature is estimated for thermal protection. These features allow for control logic that can optimally manage the temperatures of the power semiconductors and the motor to facilitate the high torque performance of the system.
The motor voltage management has also been optimized in order to reduce the current level and thereby contributes to the system’s high power performance and high efficiency. The motor also adopts magnets with reduced heavy rare earth elements. This improves heat resistance and obtains resource savings.
In addition, one of the novel features of the new EV is e-Pedal that provides not only deceleration but also stopping by operating only the accelerator pedal. This is achieved by motor control logic of the motor and inverter system that generates the optimum motor torque in response to each road grade.