Increase of the allowable switching rate of wide-bandgap semiconductors through spectral control in a 12 v to 48 v gallium-nitride DC/DC converter
Efficient power conversion currently relies on switching modulation to accurately control the output. Typically, the switching rate is fixed, particularly for the larger power units in automotive applications. Due to the powerful peaks in the output spectrum and the electromagnetic emission associated with the distinct switching rates, the potential of new wide-bandgap semi-conductors is highly limited in vehicle applications. We present a gallium-nitride 12 V-to-48 V DC-DC converter with novel control and modulation scheme that does not only greatly reduce the peak power density of the switching distortion but allows practically full control of the shape of the distortion. In stark contrast to conventional spread-spectrum methods, the control of the distortion spectrum enables, for instance, engineering the spectrum to follow spectral limits of EMI standards in shape and to clear the dynamically changing receiver frequencies of the radio tuner to exploit the potential of switching in the medium-frequency range. The method can be implemented with standard control schemes such as PID controllers.
