Queries about DC to AC Inverters

[markfoy]

That's already how inverters work!.

Yeah! But any idea of how I can go about it? I'm thing of paralleling mosfets in H-bridge and switching them on in sets one-after-the-other. (sounds quite weired to me)

 

[Nigel Goodwin]

Doesn't make that much difference - the input current is directly related to the output current - with lower output current the input current will drop accordingly. Obviously there's a certain amount of waste, with the inverter being less efficient used at lower powers - but probably not enough to make it worth while making it far more complicated?.

 

[audioguru]

Why do you need a 1500W inverter? At max output its current from a 12V battery is about 150A. A big car battery will boil in a couple of minutes and will be dead.

Conserve electricity then use a smaller inverter.
Complain to your electrical utility that their electricity is not reliable.

 

[markfoy]

Well I bought a 1400W inverter (24V DC supply and didn't run my battery) from India and it worked fine until a section of it got fried by extreme high voltage from the utility while I was charging the battery. Obviously the 24v dc source made it draw less current. But going by the chassis temperature, and the average length of time it was on, I believed it drew much lower than you would expect (ordinarily it should gulp 58.3A continually although I rarely load it to its full capacity).

Now I'm thinking of building something similar. Oh! I couldn't return to the manufacturer cos the warranty period elapsed.

 

[Gordz]

The modified square wave you mention is likely to be a 'modified sine' wave I think. This is probably a 'stepped sine'. Invertors of this nature are not a beginners project.

 

[mneary]

ordinarily it should gulp 58.3A continually

1) You should expect it to draw a small standby current (IMHO much less than 10% of its full-load rating) when unloaded. It should only draw the full input current at full load.

2) If you're looking for a project that would result in a working inverter, it should be far less difficult to repair the one that failed.

 

[markfoy]

2) If you're looking for a project that would result in a working inverter, it should be far less difficult to repair the one that failed.

That's what I tried to do at first until I found out that the burnt chips seem to be custom made and are not available off the shelve.

 

[mneary]

I wouldn't expect to find many, if any, custom parts in an inverter. Production volume is too low for that. More likely a house marked part or a microcontroller.

Tell us more about the burnt part? Do you have a schematic of the area surrounding the bad part(s)? Inverter maker and model number?