Aperiodic pulse-modulation technique to reduce peak EMI in impedance-source DC-DC converters

The use of wide-bandgap (WBG) devices in power converters provides several advantages in terms of efficiency, power density and low cooling requirements. However, a potential unwanted side-effect is the increased electromagnetic interference (EMI) noise, the basis of which is the high di/dt and dv/dt realized by the characteristic sharp rise and fall switching offered by the WBG power switches. To suppress the EMI, this paper presents a generic framework for the generation of an aperiodic carrier signal, which can be extended to drive multiple switched power converters. The aperiodic modulation scheme is implemented in a MATLAB Simulink environment and realized on a field-programmable gate array (FPGA) development board through an auto-code generation feature offered by a hardware description language (HDL) coder. Finally, the efficacy of the proposed aperiodic modulation methodology has been tested on a quasi-Z-source DC-DC converter. A 9 dB suppression in the peak conducted EMI emissions was demonstrated with no adverse impact on the voltage gain and efficiency of the power converter.