Resonant, high voltage, high power supply for atmospheric pressure plasma sources

In this work, a new concept for a resonant, high voltage, high power supply for operation with atmospheric pressure plasma sources is presented. The output voltage is a sinusoidal shaped signal in the frequency range of 1...100 kHz and with an amplitude up to several kV. From the electrical point of view, atmospheric pressure plasma sources are strongly capacitive loads. For this reason, it is an advantage to make this capacity part of a resonant circuit. The excitation of this circuit is realized by use of pulse width modulated (PWM) pulses. Their width is controlled by a controller whose input is fed by the output voltage and/or the current of the circuit The pulses are synchronized with the zero point of the resonant circuit current. In the presented concept the large smoothing capacitors in the intermediate direct current link can be avoided. The main advantages comparing to existing power supplies are the high efficiency, small voltages and switching frequencies of the high power transistors, low costs, good scalability and resistant against short cuts in the plasma source.