Exploring EV traction inverter design trends

A traction inverter converts battery energy into power that controls torque and speed, giving it the most influence over an EV’s range, performance and driving experience. Torque is proportional to motor size, while power provides torque and speed. Keeping power constant, if you want to reduce the motor size and torque, you need to increase the speed. This is a challenge, as component sizes typically increase with power level and torque, especially if there are design inefficiencies such as losses from mechanical or electrical nonidealities. It becomes important, then, to reduce not only the size of the motor, but also the electrical system to the traction inverter itself.

In order to extend driving range and reduce motor size and weight without compromising the power level, a traction motor needs to be able to run at higher speeds (>30,000 rpm). This requires fast sensing and processing, as well as the efficient conversion of DC to AC voltages. To achieve these goals, traction inverter design trends include using advanced control algorithms, employing SiC MOSFETs for the switching transistors in the power stage, using high-voltage 800-V batteries and integrating multiple subsystems to obtain high power densities.