sine wave inverter using gate drivers and mosfets

[vedantam]

i had a doubt in interfacing ir2127 gate drivers with mosfets using micro controller(no opto coupler used). whether vcc to ir2127 is to be given with micro controller gnd or with respect to which gnd.
i am here attaching pdf of rough schematic

 

[neddie]

Hi there.
First of all , you are missing the bootstrap caps on your ic's , from Vb to Vs. Your highside drive won't work without them :0(

You can connect the controller chips directly to your micro. Com , pin 4 , is ground of your driver chip and micro.Vcc can be about 12V. Opto's will protect your Micro in the event of a bridge
failure , which could put your external DC voltage onto the fet gates , and hence your micro.

Try looking at the IR2104 driver chip. It drives the high side and lowside fets in one package. Will make life easier for you. 2 less driver chips.2 less pins used on the micro(may not be important) Built in dead time.
In your current application , you have to provide the deadtime from your micro, Some have this feature built in , which makes life easier for you. If not , make sure you get it right or you'll be replacing fet's at a prodigous rate :0)
The IR2104 "does not" have any form of current sensing though , you will have to provide that your self.
Hope this helps a little.

 

[vedantam]

thanks neddie, for ur information. yes i had a booststrap cap but i have drawn a rough schematic. my doubt is on high side of every driver bottom two drivers Vs pin is connected but for Q1 and Q2 what to be done (seperate ground to be maintained or not)

 

[neddie]

The high side drivers also connect to the same ground. The 2127 drives the highside gate voltages all the way from 0. For instance if your ext DC supply is 300V and vcc to the 2127's is 12V , the top 2 2127's HO outputs(the gate drive) go from 0V to 312V,
when the input to the 2127's goes from 0V to 5V.
Do you have LTspice? If so I can send you a sim using the ir2104(very similar) , so you can see how it functions.

 

[vedantam]

no i don't have ltspice. can pls tell me what it is? where to download it

 

[neddie]

Hi there.
You can get LTSpice IV here.
https://www.linear.com/designtools/software/
Also download the User guide and spend a little time going through that. You should
be up and running quite quickly , as it's pretty easy to use , at least for simple stuff.
I'll PM you then CCT that you can run on LTspice. Once you've installed it , just open the cct and run it to see what's going on. The subcct's/ models are included in the schematic , so you should'nt havew any problems.
cheers
Rob