three phase ac to dc to ac converter

can any one suggest article regarding the design of three phase VSI. and i need the step by step design guide.
thanks and regards,
Malai

Unfortunately there are so many types of VSI designs, you can't have a single article describing them all.

If you already have background knowledge about power electronic converters in general and VSI's in particular then below are some tidbits from my experience. If you don't then get a good book on electric drives like Rashid or B.K.Bose, Ned Mohan, many more.

I am assuming you'll be designing a 3-leg VSI. First determine your load voltage and current requirements thereby selecting appropriate power switches(MOSFETS,IGBTs, Thyristors etc). Choose a modulation scheme, from simple 120-degree,180-degree conduction modes to full blow SVM techniques can be used. This again depending on your technical background may take forever to get it right. For the DC-link side get single-phase/three-phase rectifier modules with required voltage and current ratings. Also don't forget to add storage capacitors of reasonable capacitance, which can be calculated from the acceptable ripple and load current in your inverter

Once you get the 3-leg inverter ready, you'll be needing gate-drivers(assuming only MOSFETs and IGBTs here as thyristors get too complicated). Gate drivers can be simple GDT(Gate drive transformers) or full-blown ICs that does everything for you, I had some good experience with controllers from International Rectifier.
http://www.irf.com/product-info/cic/fsgatedriverics.html. These gate drives come in very handy to test your design with different modulation schemes as they act as an interface between your microcontrollers and the VSI. Be sure to buy them in dozens, I know I would.

If you have questions about something in specific, just ask. I designed and implemented several VSI's during my undergraduation, I've also worked on Z-source converters for a while, if you are interested.

Also there are some small things to remember when getting your circuit boards like dv/dt spikes, isolation, bootstrap supplies, shoot-through conditions, twisted-wire gate driving etc etc, which can go a long way in high power and high frequency designs. I burned contless, drivers and mosfets when I was building an audio-modulated SSTC(Solid-State tesla coil), its no fun seeing your board catch fire then desoldering and resoldering, yuck.

Good luck.