Virtual Fractional-Order-Inductor Based Second Harmonic Current Suppression Method

In a two-stage single-phase inverter, the pulsating output power generates a second harmonic current (SHC) at the dc port. Although the conventional virtual-resistor (VR) based control method can suppress the SHC, the SHC reduction performance is limited by its dynamic performance. To address the above issues, based on the unified small-signal model of the dc-dc converter, a virtual fractional-order-inductor (FOI) based control method is proposed in this article to reduce the SHC and improve the system dynamic performance. The order and magnitude of the fractional-order inductor can be modified arbitrarily. A negative order inductor is constructed in this article to reduce the SHC and improve the system dynamic performance. In addition, the proposed virtual FOI-based control method can improve the stability of both dc-dc converter and the cascaded system. The comparison of the proposed fractional-order inductor and conventional VR-based control method is given and the design method of key parameters is presented. Finally, an 800-W two-stage single-phase inverter with the upstream boost converter is fabricated and tested in the laboratory to verify the effectiveness of the proposed control method.

Automated summary

In this article, a virtual fractional-order inductor (FOI) based control method is proposed to reduce the second harmonic current (SHC) and improve the dynamic performance of the system. The order and magnitude of the fractional-order inductor can be modified arbitrarily, and a negative order inductor is constructed to enhance system stability. The effectiveness of the proposed control method is verified through the fabrication and testing of an 800-W two-stage single-phase inverter.