solid state H.F.welder

Voltage type resonance inverter also called series connection type resonance inverter is the most critical part of the whole solid state H.F. power supply; fig 2 shows the structure, output voltage and current wave of inverter module. By controlling connection and disconnection alternatively of MOS 1&3, MOS 2&4, the series connection type inverter output voltage uH is close to square-wave, due to the inverter output voltage frequency is near by resonance frequency of resonance tank circuit, and now the inverter output voltage fundamental wave from resonance tank circuit to inverter has the minimum impedance value, the maximum impedance value to other high harmonics, therefore load current iH is close to sine waveform.