Analysis and Design of Resonant Inverter for Reactive Gas Generator Considering Characteristics of Plasma Load

Abstract

This paper analyzes a resonant inverter to generate plasma. The resonant inverter consists of a full bridge converter, resonant network and reactor to generate a magnetic field for plasma generation. A plasma load has very distinct characteristics compared to conventional loads. The characteristics of plasma load are analyzed through experimental results. This paper presents the study on the resonant network, which was performed in order to determine how to achieve a constant current gain. Another important contribution of this study is the analysis of drop-out phenomenon observed in plasma loads which is responsible for unpredictable shutdown of the plasma generator that requires stable operation. In addition, the design process for the resonant network of a plasma generator is proposed. The validity of this study is verified through simulations and experimental results.

Fig. 1. Basic structure of the reactive gas generator

Fig. 2. Impedance of plasma load when the operatingfrequency varies

Fig. 3. Impedance of plasma load when the primary currentof the reactor varies

Fig. 4. Comparison of current gain between conventionaland plasma loads

Fig. 5. Circuit diagram of resonant inverter for reactive gas generator

Fig. 6. Current gain (H) for γ 1=

Fig. 7. Phase difference between inverter voltage and

Fig. 8. Proposed control diagram

Fig. 9. Simulation waveforms (Ro=2Ω, Iplasma*=30A)

Fig. 10. Simulation waveforms (Ro=6Ω, Iplasma*=30A)

Fig. 11. Simulation waveforms (Ro=6Ω, Iplasma*= 20A)

Fig. 12. Experimental waveforms

Table 1. Specification of the reactive gas generator