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ASPENCORE GUIDE TO SILICON CARBIDE
T
he rollout of electric vehicles continues to acceler- ate despite global shocks such as the Covid-19 pan- demic, with the International Energy Agency pro-
By Anup Bhalla
SiC allows substantially higher switching frequencies with low dynamic losses, which, in turn, allow the use of smaller, lighter, and cheaper magnetic compo- nents. This enables a virtuous circle of decreasing energy cost and longer range. “Generation 4” SiC FETs exhibit particular performance advantages that position them as leading con- tenders in the race to increase efficiency.
SiC Use Proliferates in
New EV Designs
moting a 30% market share for EVs by 2030 (the EV30@30 Campaign). This agency’s “Sustainable Development Scenario” foresees an increase in global EV stock from about 7.6 million in 2019 to about 245 million in 2030, repre- senting 36% year-on-year growth.1 For this to happen, EVs must be seen as practical and financially viable to the user. An enabler for those requirements is high-efficiency power conversion in the powertrain and battery-charging stages for faster charging, increased range, and lower energy costs.
Efficiency gains form a ‘virtuous circle’
Power-conversion efficiency is largely dictated by losses in semiconductor switches. Older technologies such as IGBTs are now giving way to wide-bandgap devices, particularly silicon carbide, in the form of JFETs, MOSFETs, and SiC FET cascodes. The change has been enabled by reducing FET on-resistance to yield conduction losses comparable to or better than those of IGBTs at medium-power levels, along with device voltage ratings suitable for battery systems in the higher ranges of 500–800 V. Also, compared with IGBTs,
FIGURE 1: THE SiC FET
The SiC FET: A short introduction
The SiC FET (Figure 1) is a high-performance alternative to Si or SiC MOSFETs, formed as a normally off cascode of a SiC JFET driven by a low-voltage, co-packaged silicon MOSFET. This arrangement has the benefits of SiC — low dynamic losses and the ability to withstand high-voltage, high- temperature operating environments — but with an easy, stable gate drive and best figures of merit for on-resistance × die area and on-resistance × switching energy. It has a lower-