Full Grid Voltage Feedforward for Hysteresis Current Control Critical Mode LCL-Type Grid-Tied Inverters

Hysteresis current control is considered an effective method to achieve full power range zero-voltage-switching (ZVS) operation and good gird current quality of the critical mode (CRM) LCL-type grid-tied inverter. However, with the large-scale grid connection of distributed power generation systems (DPGS), the control performance of the LCL-type grid-tied inverter is seriously challenged by the large number of harmonics contained in the point of common coupling (PCC). In this paper, by combining the physical interpretation of the full grid voltage feedforward (GVF) and the physical model of the hysteresis current control (HCC) CRM LCL-type grid-tied inverter, a full GVF scheme is proposed for improving the grid current THD of the single-phase HCC-CRM LCL-type grid-tied inverter. All harmonics caused by the distorted grid voltage can be significantly suppressed by feeding forward the derivative term of the grid voltage to the hysteresis-band reference. A 1-kW single-phase LCL-type grid-tied inverter is built, and experiments are conducted to verify the effectiveness of the proposed strategy.