Buck-boost impedance networks

Most inverters designed to date can only perform either voltage-buck or boost operation with buck-boost mode usually attained by introducing additional active semiconductor devices and passive components to the inverters. Although effective, adding active switches will complicate the inverter control, and push up the overall system costs. Therefore, alternative topological solutions are of interest, and should preferably be implemented using only passive LC elements and diodes, connected as unique impedance networks. A number of possible network configurations are now investigated in this paper, and are respectively named as Z-source, H-source, EZ-source and their respective "inverted" variants. The presented impedance networks can either be used with a traditional voltage- source or current-source inverter, and can either be powered by a voltage or current source. All impedance networks are shown to produce the same voltage gain under the same operating conditions, but structurally, they have their respective advantages and disadvantages, which are thoroughly described throughout the paper. Experimental results captured using a laboratory prototype are also presented for confirming the practicalities and performances of the described impedance networks.