Reducing circulating currents in interleaved converter legs under selective harmonic elimination pulse-width modulation

Interleaving of voltage source converter legs enables higher output currents per phase, effectively increasing the power rating without increasing semiconductor ratings. Different switching patterns between the converter legs increase the number of Thevenin output voltage levels and, hence, the quality of the waveform but also generate circulating currents within one phase. This paper proposes a controller for interleaved converter legs under selective harmonic elimination pulse-width modulation (SHE-PWM) aimed at reducing the circulating current within the legs of each phase. The controller is used in combination with optimally selected SHE-PWM patterns to minimise the peak value of the circulating current. The proposed controller is applied in two interleaved three-level active neutral-point-clamped converters and simulation results demonstrate their performance.