A Cross-Regulated Closed-Loop Control for Hybrid L-Z Source Inverter

Recently, switched inductor-impedance source inverter (L-ZSI) based hybrid converter was reported as a potential candidate for the dual output (dc and ac) applications. This converter has two operating modes based on inductor current nature: 1) continuous current mode (CCM); and 2) discontinuous current mode (DCM). However, the converter performs well only during CCM. To get rid of problems present in hybrid L-ZSI, modified hybrid L-ZSI (MHLZSI) was reported. To demarcate the CCM and DCM, boundary condition was derived based on the average inductor current. However, the actual boundary condition is dependent on the combined effect of inductor current ripple and average inductor current. In this paper, theoretical analysis is presented by taking into account the effect of inductor current ripple. Furthermore, it is proved that MHLZSI is capable of achieving higher gain when operated in DCM. In addition, a closed-loop control for MHLZSI is designed. State space analysis is presented to derive the output to control transfer function for both dc and ac loads. Both the controllers are designed based on PI control to ensure cross regulation. Theoretical analysis is validated by experimental analysis.