cws wrote:Hi ,as an installer trying to compete with the Mc Solar companies, the use of transformerless inverters seems to be the go, does anyone have any thoughts on the merits of one type over another.I always liked the idea of a great big transformer,it seems like a more robust design,but............?
cws wrote:Thanks Joey, i am familiar with the pro's. I have service contracts with 2 major inverter manufacturers and since the inception of tranformerless inverters i have been to a couple that have failed ,this rate, although very small concerns me, as, up till now ,for the ten or so years that i have been doing this ,the failure rate for tranformer type inverters seems much less , i can't prove it, but the quality of the mains grid waveform may effect transformerless inverters more than their predecessors.Any thoughts?
bradley.jarvis wrote:I think you'll find that most transformerless inverters actually use IGBT's not MOSFET's which are better at switching high current. I think that the high end cost relative to the component cost has been offset by the R&D that the companies making them have had to invest. In the long run the transformerless will become much cheaper. I am designing a 3-phase inverter which should have no trouble switching upto 600V 50A using IGBT's, the cost of component's(from Farnell and Mouser) is no more than $200(not including PCB).
bradley.jarvis wrote:Hi Joey,
You are correct Mosfets and IGBT's are both quite suitable and consideration for both must be made. I have read that article before while doing research for my inverter. I have ended up choosing IGBT's for various reasons.
I should have probably said that IGBT's are also another technology that is used for inverters, not just MOSFET's.
I don't really have that much time, but designing has been fun (I work with AVR embedded processors and the new xmega processors is perfect for my application. I am currently working on isolation). I can't wait to get to building and testing, that will be fun. It is for a motor control application, it will be a >3kW transformerless inverter (3 phase but I will be running it straight off ~80-100VDC, no voltage boosting required). Hopefully it is reliable, a good transformer would be too big and bulky for my application.
Joey wrote:Hi Brad ,
Would be fantastic if you could keep us posted on the project , it's not something many could even dream about doing .
Something that would interest you in your work( sorry people if this is off topic ) but have recently just purchased the new APR5000 DZ
http://okay.com.au/okayshop/product_inf ... 3urrinhj94
Ends up closer to 55K by the time you get all the extra's you need , but what a machine!
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