Symmetric and asymmetric operating modes of hybrid cascade frequency converters

The hybrid cascade frequency converter contains a diode rectifier connected to the network and a three-phase autonomous voltage inverter, as well as a transformer connected in parallel to the network, supplying units with active rectifiers and single-phase voltage inverters. On the load side, three-phase and single-phase inverters are connected in series. The structure of the converter allows to use the transformer for a partial load power, increase the voltage at the output, provide the required quality of voltages and currents at the input and output of the converter, power the load when some of the blocks fail. The model of the converter and investigation results are described. Control algorithms that provide power distribution between the blocks, the required quality of voltages and currents at the input and output, as well as the efficient operation of the converter when disconnecting part of the power blocks are proposed.