A current-fed asymmetric LLCC resonant converter for DBD applications

In this paper, a current-fed asymmetric full-bridge LLCC resonant converter is proposed for the dielectric barrier discharge (DBD) applied to the surface treatment. Compared with a previous design, the asymmetric structure with no front-end buck circuit and only two reverse-voltage blocking diodes is adopted to reduce the component count and circuit complexity. Moreover, the phase-shift control of this asymmetric full-bridge circuit is employed to regulate the AC output voltage across the DBD load. The leading switches realize ZCS by monitoring the energy of the resonant tank at the very beginning of the overlapping time of the gate signals. The lagging switches achieve ZVS by adjusting the change rate of the voltage across these switches through three small auxiliary capacitors. The method of rectifier compensated first harmonic approximation (RCFHA) is utilized to derive a curve of the transformer turn ratio and equivalent inductance, which reduces the design complexity caused by the magnetic integration technique. The experimental results from a 500W prototype are provided to verify the effectiveness of the proposed converter.