Power Electronics Europe April/May Issue 2022

22 SIC DRIVERS www.analog.com Issue 2 2022 Power Electronics Europe www.power-mag.com Range Extension Promise of SiC in Traction Inverters There are two major disruptions currently affecting the future of vehicular transport and semiconductor technology. We are embracing a new and exciting means to propel our vehicles cleanly with electrical power, while simultaneously re-engineering the semiconductor materials that underpin electric vehicle (EV) subsystems to maximize power efficiency and, in turn, EV driving range. Timothé Rossignol, Marketing Manager, Analog Devices, France Government regulators continue to mandate that automotive OEMs reduce the overall CO 2 emissions of their vehicle fleets, with stringent penalties for noncompliance, and EV charging infrastructure is beginning to proliferate alongside our roadways and parking areas. For all these advancements, however, mainstream consumer adoption of electric vehicles remains stunted by lingering concerns over EV range limitations. Complicating matters, the larger EV battery sizes that could extend EV range and neutralize consumers’ range anxiety threaten to simultaneously increase EV prices—the battery accounts for more than 25 % of the final vehicle cost. Fortunately, the semiconductor revolution occurring in parallel has yielded besides others new wide band gap (WBG) devices such as silicon carbide (SiC) MOSFET power switches that can help shrink the gap between consumers’ EV range expectations and OEMs’ ability to satisfy them at competitive cost structures. Figure 1 shows the power conversion elements in EVs. The traction inverter converts the HV battery’s DC voltage into AC waveforms to drive the motor, which in turn propels the car. The battery to motor signal chain is depicted in Figure 2. To deliver on the range extension, each block should be designed for the highest efficiency level. Reduced inverter size and cost The inherent benefits of SiC-based power switches with regard to power density and efficiency are well understood, with key implications for system cooling and size. The evolution to SiC promises 3 smaller inverters at 800 V/250 kW, with additional significant size and cost savings on companion DC link film capacitors. Compared to conventional Silicon, SiC power switches can enable better range and/or a reduced battery pack, giving the switches a favorable cost comparison from the device level to the system level. At the intersection of these range and cost considerations, the traction inverter remains the epicenter for innovations aimed at unlocking further EV efficiency and range gains. And as the most expensive and functionally important element of the traction inverter, SiC power switches need to be controlled very accurately to realize the full benefit of the extra switch cost. Figure 3 shows voltage and current waveforms at turn-on (left) and turn-off (right). In SiC environments, dv/dt will exceed 10 V/ns, which means no more than 80 ns to switch an 800 V DC voltage. In a similar way, a 10 A/ns, Figure 1: Power conversion elements in EVs. The traction inverter converts the HV battery’s DC voltage into AC waveforms to drive the motor, which in turn propels the car Figure 2: The battery to motor signal chain. To deliver on the range extension, each block should be designed for the highest efficiency level