Making a 300 Amp square wave AC inverter

Ignoramus965 · 2005-09-08T22:48:43+00:00

I am considering a project to build a 300 amp, about 40V inverter thatwould invert DC into square wave AC. That's for converting a DCTIG welder into a square wave AC TIG welder. I do not yet have thewelder, but may get it in a few days.I am coming here after some preliminary discussions on I have some basic knowledge of physics and some knowledge ofelectricity to start with, but I am not well familiar with solid stateelectronics. I built a well functioning phase converter, and the onlysolid state piece that I ever used was a crydom relay with zerocrossing.The objective is to make the inverter cheaply but in an effective manner.With that introduction in mind, let me describe what is my currentplan.The plan is to set up an H bridge, using 4 arrays of MOSFETs. Thesemosfets would be controlled by variable frequency AC signal. Togenerate this signal, I want to use an HP 204C oscillator (which Ihave), coupled to an appropriate amplifier (which I do not have).HP 204C produces 2.5 volts and needs to be amplified about 16 times.Signal from amplifier would control mosfets, although, possibly, Iwould also use diodes to prevent negative voltage from being sent tothe gate of mosfets.The H bridge would produce inverted, almost square wave AC.The mosfets that was recommended would be something like this?Ref=199933&Row=338490&Site=USFor gate input, I would need to produce about 40 V AC (if I am notmistaken), that sort of determines what the amplifier should be. Lookslike wattage requirements for the amplifier are minimal.Is that a sensible plan, and if so, what would be your suggestions. Iknow how to solder, use a multimeter and use a drill press. I am amoderately handy person and am open minded and welcome suggestions.Thanks!i