Diode rectifiers are very popular in industry. However, they include large low-order harmonics in the input current and do not satisfy harmonic current content restrictions. To reduce the harmonics to the power system, several methods have been introduced. It is heavy and expensive solution to use passive filters as the solution for high power application. Another solution for the harmonic filter is utilization of active filter, but is too expensive solution. Diode rectifiers with configurations using switching device have been introduced, but are very complicated.
The combined 12-pulse diode rectifier with the square wave-auxiliary supply has been introduced. It has the advantages that auxiliary circuit is simple and inexpensive compared to other strategies.
The advanced wave auxiliary voltage supply in this thesis is presented as a new solution. It shows the improved result for reducing THD compared to the case inserting a single phase square wave auxiliary voltage supply. Especially, for the case with a low load factor, it shows a outstanding improvement of THD.
Theoretical analysis of the combined 12-pulse diode rectifier with the advanced auxiliary supply is presented and control methods of the auxiliary supply is proposed. The reduction in the input current harmonics is verified by simulation using software PSIM and experiment.