The Z-source converter (ZSC) is an alternative power conversion topology that can both buck and boost the input voltage using passive components. It uses a unique LC impedance network for coupling the converter main circuit to the power source, which provides a way of boosting the input voltage, a condition that cannot be obtained in the traditional inverters. It also allows the use of the shoot-through switching state, which eliminates the need for dead-times that are used in the traditional inverters to avoid the risk of damaging the inverter circuit.
Dynamic modeling of the ZSC from different perspectives has been studied in the literature. So far, based on these models, the peak dc-link voltage has been controlled using direct measurement, or through indirect control using measurement of the capacitor voltage. Direct measurement control requires a peak detection circuit due to the pulsating nature of the dc-link voltage. Indirect control using the capacitor voltage makes the peak dc-link voltage sensitive to line disturbances.
In this research, the peak dc-link voltage is reconstructed using the measurements of the capacitor and input voltages. The ZSC is then controlled using two methods; namely the Voltage Mode (VM) and Current Programmed Mode (CPM). The two control laws for the ZSC with inductive loading are derived based on a small signal model of the converter. In CPM, since the order of the system is reduced by one, it is possible to achieve a dynamic performance similar to VM control with a simpler compensator. Performances of both VM and CPM controlled ZSC are verified by the simulation and experimental results for line and load disturbances. The simulation and experimental results for both steady state operation and disturbance rejection cases observed to be comparable. Line disturbance rejection of CPM controlled ZSC is found to be better than the VM control case. Both control methods showed satisfactory dynamics in case of the load disturbance rejection.