A Novel Spectral Control Method for an Automotive Gallium Nitride DC-DC Converter

Common power electronic devices currently over-whelmingly rely on fixed-frequency modulation schemes to synthesize output voltage levels between the fixed voltage levels available to the semiconductors. The distinct switching rate causes large peaks in the spectrum of the output voltage concentrated around the switching frequency and its harmonics, particularly for wide-bandgap semiconductors with their possible high switching frequencies in sensitive spectral ranges. We present a novel control and modulation scheme for DC-DC converters that greatly reduces the peak power density of the switching distortion. The proposed scheme has the ability to shape the distortion of the output spectrum according to a specified target and can be implemented with standard control schemes such as PID controllers. The method is presented and implemented on a prototype automotive 48 V-to-12 V gallium nitride buck converter.