What are the EMC challenges of SiC devices in frequency converters?

The new EMC challenges brought about by the application of SiC power devices in frequency converters mainly stem from their higher switching speeds and frequencies. The difficulties include: extremely high dv/dt and di/dt, leading to stronger near-field electromagnetic interference and richer spectral components, potentially extending to hundreds of MHz or even GHz, which may cause traditional filter designs to fail. Higher switching frequencies shift the noise fundamental frequency upwards, placing higher demands on the frequency characteristics of filtering components. SiC devices are more sensitive to drive loop noise, and their lower gate threshold voltage requires extremely pure drive signals, increasing the difficulty of anti-interference design. Parasitic parameters within the device package have a more significant impact, requiring more precise layout to control loop inductance.

Traditional absorption circuits may become ineffective or suffer excessive losses at high frequencies. Addressing these challenges requires new design strategies: employing driver chips specifically optimized for high frequencies, with shorter propagation delays and higher CMTI; using ultra-low inductance packaging and connection technologies, such as direct bonding of copper substrates; designing EMI filters covering a wider frequency band and with better high-frequency performance, which may require the use of high-frequency materials such as nickel-zinc ferrite; and optimizing absorption circuits by using capacitors and resistors with good high-frequency characteristics. Leveraging simulation tools, high-frequency EMI behavior can be predicted early in the design process. Echotronics is developing filtering and driving solutions for wide-bandgap semiconductor applications to address these challenges.