And Passive Welding Machine Is Equipped With The 2kw Working Frequency Inverter Power Supply

Intermediate frequency passive welding is a light,movable welding equipment,which is small and light,and self-powered by its in-built intermediate frequency generator with 500～1000Hz.It has widely used in field constructions such as petroleum pipeline,railway and bidge cnstructions..The generator in welding can not be used to supply power for detecting instrument and mud pump in field constructions, as in built generator can not give alternating current with 50 Hz power-frequency.Under this condition the welding machine factory proposed the project and accomplished in cooperative mode.The project is develop a 2000W 50Hz square wave inverter power source with power frequency.It has been completed and has corollary used with 6～8KW 500 Hz intermediate frequency passive welding produced by the factory on Dec.2007.According to the technical requirements,each part of this inverters are all supplied by medium frequency power in welding.The most technical difficulties in development are system must have the abilities to support the starting full voltage and hard switching of two 750w's mud pump and resistance strong electromagnetic interference made by arc spark occurred with 3～5 welding machines flame sterilization simultaneously in the several metres,besides it has to adapt to bad climatic environment in field,meanwhile,also have requirements in cost,volume,anti-seismic,etc.So,the main characteristic of this project is use some mature techniques to comprehensivly solve new problem in practically product development through reasonable design circuit,layout and placement of the device,model of conducting wires and strictly debugging steps.The system is composed of five unit circuits,main circuit,pulse wave generating circuit,driving circuit,protection circuit and power supply.Main inverter switch element is 60A 800V IGBT,control circuit and driving circuit are all using specific integrated circuit(ASIC),self-designed protection circuit is using universal comparison programmer circuit and discrete components to compose a over-current, undervoltage and overheat protective circuit with a strong anti-interference ability to solve security threat of switching devices made by motor direct hard starting and hard switching.The main circuit adapts energy snubber transfer pattern,setting a energy storage snubber circuit on load which can limit starting impulse current as well as absorb turning off sparkle.Better solved power IGBT's security threat problem from motor leakage reactance's energy storage when load motor hard starting and hard switching.In solving anti-interference's problem,firstly setting delay link or filter link in easy interference point of system through principle diagram design,in order to reduce the impact on system circuit from merging into interference signal.On circuit elements routing,layout and process design,although using computer aided design, mainly artificial design,sloved the problem that exterior strong electromagnetic signal impact on system working thoroughout by reasonable arranging the position of filter capacitors,adjusting routing width and using copper indouble-sided of printed circuit board.