Control and Performance of a Pulse-Density-Modulated

This paper presents control and performance of a pulse-density-modulated (PDM) series-resonant voltage-source inverter developed for corona discharge processes. The PDM inverter produces either a square-wave ac-voltage state or a zero- voltage state at its ac terminals to control the average output voltage under constant dc voltage and operating frequency. This results in a wide range of power control from 0.5% to 100%, even in the corona discharge load with a strong nonlinear char- acteristic. A 30-kHz 6-kW surface treatment system consisting of a voltage-source PDM inverter, a step-up transformer, and a corona discharge treater shows the establishment of a stable corona discharge in an extremely wide range of power control and, therefore, succeeds in performing both strong and weak surface treatment processes for film.