An improved voltage balancing control method for single‐phase cascaded H‐bridge rectifier considering grid‐side DC offset

Abstract

Abstract An improved voltage balancing control (VBC) method is proposed in this paper to optimize control performance of single‐phase cascaded H‐bridge rectifier (CHBR). Firstly, the steady‐state error of the VBC method based on capacitor energy estimation is analyzed. An error compensation method is therefore presented to eliminate the steady‐state error. The proposed method delivers fast dynamic performance without steady‐state error. In addition, it requires less parameter tuning than traditional proportional‐integral‐based (PI‐based) VBC methods, and coupling effect between the upper‐ and the lower layer control system is also eliminated in both dynamic and steady state. Moreover, a mixed second‐ and third‐order generalized integrator (MSTOGI) method is applied to suppress the dc offset of grid voltage, which may occur in the process of sampling or conversion. Finally, a physical experiment platform is developed and a series of comparisons are given to verify the feasibility of the proposed method.