BUCK-CHOPPER AND BI-DIRECTIONAL CHOPPER FOR MULTILEVEL CASCADED HBRIDGE INVERTERS

A cascaded H-bridge (CHB) inverter for higher rated power conditioning systems which operates at medium voltages while providing high power quality and low dv/dt. By incorporating battery energy storage, the power conditioning system operates at night to provide power to a load or grid and stabilizes the system during sudden changes in climatic conditions. Various energy storage system (ESS) configurations such as AC side coupled ESS, dual active bridge based ESS, and chopper based ESS configurations for cascaded H-bridge inverters are described. A comparison of these configurations on the basis of cost, control complexity, controller hardware requirements was performed and the advantages of chopper based ESS configurations over other ESS configurations was demonstrated. A control algorithm for the chopper based configurations was developed to operate the system in standalone and grid-connected modes of operation.