Abstract: Aiming at the issue that the existing zero-sequence voltage compensation strategy cannot effectively suppress the active power backflow of cascaded H-bridge（CHB）photovoltaic（PV）grid-connected inverters during asymmetric grid faults,the limitations of the existing zero-sequence voltage compensation strategy are quantitatively analyzed,and a positive-negative sequence maximum-minimum harmonic zero-sequence voltage injection control strategy is proposed,which can effectively reduce the overmodulation zone,expand the operation range of CHB PV inverter under inter-phase short-circuit fault condition. Finally,the effectiveness and feasibility of the proposed control strategy are verified by experimental results.