# Emerging Technologies for Advanced Power Electronics and Machine Design in Electric Drives
## 3 Semiconductor Switch Technologies
### SiC WBG Semiconductors  
The first SiC Schottky diodes were developed for relatively low rated voltages in order to ensure low forward voltage drops and low reverse current values. Their main advantage was the extremely low reverse recovery charge (\(Q_{rr}\)) and the reverse recovery time (\(t_{rr}\)), resulting in very low reverse current peaks at the onset of reverse polarization. As a result, the switching losses of the diode were practically negligible, while the turn-on losses for switching transistors were also reduced.  
Currently, 3.3 kV full SiC MOSFETs, IGBTs and diode components and modules are available, which are particularly suitable for high-performance traction inverters (Figure 13) [127,128]. There are also reports of the construction of a solid-state transformer for connection to the medium-voltage grid using 15 kV SiC IGBTs and 10 kV SiC MOSFETs [129,130]. However, such high-performance components are not yet available on the open market. In this way, SiC technology is advancing into Si IGBT-suitable applications [131,132] or even extending the achievable limits of solid-state converters (Figure 13) [129]. Compared to Si IGBTs, the main advantages of SiC devices are high-rated voltages, low-forward-voltage drops (in on-state), as well as high switching speeds and lower power losses [133,134]. SiC devices have three times lower thermal resistance, which ensures more efficient heat dissipation and reliable operation up to 175\({}^{\circ}\) C. Due to the lower switching losses, SiC technology enables operation at two to five times higher switching frequencies compared to Si technology. This enables a reduction in the size and cost of passive components, as well as a simplification of and reduction in heat dissipation systems [135,136].  
SiC MOSFETs are driven with a recommended gate drive voltage between 0 V and 20 V, while a gate voltage of \(-\)5 V for the blocked state is preferred for increased disturbance tolerance and to achieve faster switching times [137].  
The first large-scale example of the use of SiC technology in an EV powertrain inverter for mass production dates back to Tesla's Model 3 in 2017 [138, 139, 140]. Until then, this technology was being tested and was more or less used in industrial applications. Modern generations of SiC MOSFETs will enable the next generation of EV powertrains. Because they operate at higher switching frequencies, inverters can supply motors with lower inductance values. This will enable the use of smaller motors to meet power requirements  
Figure 13: Illustration of typical applications with Si Thyristor GTOs, Si IGBTs, Si MOSFETs, SiC MOSFETs, and GaN transistors, positioned according to their approximate rated values in terms of output power (kW) and operating frequency (kHz).  
at higher speeds [140]. Modern powertrains will therefore be more compact and energy efficient, and, as a result, reduce the contribution to the overall weight of vehicles and enable longer ranges. SiC MOSFETs with rated voltages in the range of 650 V to 750 V are suitable for the 400 V battery voltage level, while 1200 V components are suitable for the 800 V level. SiC technology also enables the construction of compact, lightweight and efficient on-board chargers for a bi-directional power flow of up to 22 kW [141].