Improved selective harmonics elimination (SHE) scheme with online harmonic compensation for high-power PWM converters

Due to the superior harmonic performance at low switching frequency, selective harmonic elimination (SHE) modulation scheme is commonly adopted in high-power PWM converters to reduce the low-order PWM harmonics. However, as an offline modulation technique, the SHE scheme itself lacks the capability to actively compensate the grid background harmonics. To realize the active compensation ability of the SHE-modulated PWM converters, this paper proposes an active compensation method through the jittering of SHE phase angle. The proposed method can enable the high-power PWM converters´ system to real-time compensate the preexisting system background harmonics. An application example on a high-power PWM current-source rectifier (CSR) system is provided in this paper. Experimental results demonstrate that the proposed method can effectively attenuate the line current harmonics caused by the grid background harmonics in the high-power PWM CSR systems.