All solid-state switched pulser for NOx control

This paper describes all solid-state switched pulser for commercial air pollution control system using nonthermal pulsed plasma processing, for which a highly efficient and long life pulse power supply is required. The proposed pulser is composed of 30 series connections of pulse generating module (PGM) that can produce a 700 V/500 A/100 ns pulse with the rise time of 25 ns or less. All PGMs are connected in series through the specially designed pulse transformers to obtain 20 kV/500 A/100 ns pulses at repetition rates up to 20 kHz. Namely, each PGM is connected to the primary winding of its own pulse transformer, and the secondary windings of all pulse transformers are connected in series through the common high voltage cable. To obtain the fast rise time pulse, it is essential to minimize the leakage inductance of the pulse transformer and the wire inductance between pulse transformers. In this paper, two kinds of layout for the series connection of pulse transformers are introduced and compared to the conventional methods. Also the proposed pulser can protect itself from the overvoltage and the overcurrent conditions for the reliable operation. We minimized the losses by adopting an energy recovery circuit that returns to the source the stored energy in the clamp circuit of the primary windings of the pulse transformers. Experimental results are given for the proposed pulser under the resistor load and the wire-cylinder plasma reactor load, respectively. Experimental results show that the removal rate of NO/sub x/ gas can be reached up to 96.5% without using any kind of additives, chemicals and catalysts.