Solid State High Frequecy Working Principle

The so-called "solid state high frequency" is because it uses transistors(MOS field effect transistors or IGBT)as the main inverter components.Unlike vacuum tubes are hollow(interior is full of noble gas,so can be called "gaseous"),transistors are solid.

Solid state high frequency is an updated product of vacuum tube high frequency,and its main circuit is similar to thyristor medium frequency,but different from vacuum tube high frequency. Its basic principle is as follow: 

Normal three-phase AC(380V and frequency 50HZ in China) is converted to adjustable voltage pulsating DC by through rectifying circuit(SCR or diode and IGBT),this DC is filtered or flat wave become smoothing DC, and then go into inverter bridge(using large power transistor MOSFET or IGBT) to become high frequency current. This high frequency current is supplied to the tank circuit load resonance can be used for metal heating.Inverter bridge power units adopts modular structure.each pair power modules is same.but the number of power modules used varies depending on the equipment power.Whether the equipment is large or small, the structure is basically same.The resonant tank circuit is in series or parallel form.no high voltage and no output step-down transformer.

Compared with high frequency vacuum tubes, solid state high frequency equipment advantages as follow:

1.Good welding quality:comparison shows that the steel pipes welded by solid state high frequency equipment have uniform welded width and heat, and fewer internal and external burrs

2.Energy saving:tests shows that same specifications this welder can save more than 25% of electricity compared to vacuum tube equipment

3.Water saving:due to small self loss.does not require too much cooling water.so it consumes more than 50% less water than vacuum tube equipment of the same specifications

4.Small size and light weight:due to small size of main components(MOSFET) and also no welding transformer.filament regulators.matching coils.gate circuits.etc. So the overall volume is more than 50°/4。 smaller than vacuum tube equipment of the same specifications

5.Easy to operate: no voltage,peak voltage does not exceed a few hundred volts, so will not cause personal injury