A load balancing and control scheme to eliminate feedback problems in industrial appliances

Large single phase loads are connected to commercial power supply systems by the use of transformers. These transformers are expensive and require a lot of space. Connecting large single phase loads to the power supply systems without a transformer is very difficult because of large feedback problems, like distortions of the electrical currents of at least two phases of the power supply network, voltage distortions and a decrease of the output voltage of the power supply system at the end of the feed line. In this paper a scheme is presented, which converts a large single phase R-L-load into a balanced, three phase load and eliminates the use of a transformer. The proposed circuit and control strategy bring the power factor of the load to unity. The circuit consists of standard off the shelf components and presents an affordable alternative to costly transformers. The paper shows the possibility of connecting large single phase R-L loads directly to the power supply system without generating large distortions of the electrical currents and voltages. The expensive transformer is therefore no longer necessary