Design and Implementation of Step Up DC-DC Converter with a Cascaded Quasi-Z Source Network

This paper proposes a new topology of quasiZ-source inverter(qZSI) which is used as step-up isolated dc/dc converter for residential fuel cell (FC) power systems .The proposed topology used is cascaded quasi Z source inverter and implemented using induction motor. The cascaded qZSI is derived by the adding of one diode, one inductor and two capacitors to the traditional qZSI. The proposed two-stage qZSI has all the advantages of conventional qZSI such as voltage boost and buck functions in a single stage, continuous input current, improved reliability and adds a feature such that it reduces the shoot-through duty cycle by over the 30% for the same voltage boost factor and component stresses of qZSI. The main focus of this paper is on the power conditioning units (PCUs) for residential power systems using two stage qZSI (cascaded qZSI),single phase isolation transformer, and a voltage doubler rectifier. Theoretical analysis of the two-stage qZSI in shoot-through and non-shoot-through operating modes is presented. The simulation and experimental results are also discussed and presented using Matlab. Keywords— Quasi-Z-Source Inverter(qZSI), Cascaded qZSI, Fuel Cell(FC),Power Conditioning Unit(PCU),Voltage Doubler Rectifier(VDR),Voltage Source Inverter, Current Source Inverters