Comparison of Modulation Strategies for Common-Mode Distortion Reduction in Aircraft AC Converter Applications

Abstract:
With the ongoing development towards a more electric aircraft, active grid-connected voltage source converters (VSC) with four-quadrant operation can be a viable option compared to passive diode rectifiers due to superior harmonic performance and regenerative braking. With the challenging requirements of aircraft applications, even the selection of an appropriate modulation scheme is of fundamental importance for an optimized grid converter design which incorporates the active power part as well as the grid-side filter. Focusing on the three-phase, two-level VSC, dis-/continuous space vector modulations (SVM) and the corresponding common-mode and differential-mode distortions are investigated in terms of grid-side filter effort. Due to their beneficial common-mode spectra, alternative dis-/continuous SVMs with alternating space vector sequences are presented and covered in more detail. Based on the double Fourier integral analysis, the spectral performance of the proposed SVMs are assessed and compared.