Need help- 3 Phase Inverter
6 IGBTs are used as a switch.
How input pulses should be given to generate 3 phase a.c. inverter.(120 degree phase different).
any link welcomed.
Thank you
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6 IGBTs are used as a switch.
How input pulses should be given to generate 3 phase a.c. inverter.(120 degree phase different).
any link welcomed.
Thank youReplies
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Member • Feb 26, 2013
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Consider this circuit.Are you sure? This action cannot be undone. -
Member • Feb 27, 2013
As I find a DC supply has to used and also use
Vdc=Vac/(2)^1/2
And so for Vac we get Vdc to be about sqroot(2) times more than the desired op
If you need 230 V AC use Sqrt(2)*230V DC supplyAre you sure? This action cannot be undone. -
Member • Feb 27, 2013
Thanks to inform...but question is,
how the pulses to be given to the 6 igbts shown in figure so that we can convert to 3 phase signal.Are you sure? This action cannot be undone. -
Member • Feb 27, 2013
Why do you need to worry about that Just give DC supply to the IGBT's as per the circuit diagram No need for any pulses and allNishant PatelThanks to inform...but question is,
how the pulses to be given to the 6 igbts shown in figure so that we can convert to 3 phase signal.Are you sure? This action cannot be undone. -
Administrator • Feb 27, 2013
#-Link-Snipped-# : Please use the file upload facility so that images appear within the posts 😀Are you sure? This action cannot be undone. -
Member • Feb 27, 2013
#-Link-Snipped-#, he is mentioning about the firing pulses. Well, it matters!
#-Link-Snipped-#
There are two modes of operation 180 degrees mod and 120 degrees mode. In each of these modes, the time period for which the IGBTs has to be in ON state are different. In 180 degree conduction mode, each semiconductor switch will conduct for 180 degrees (that is 10ms for 50Hz) and at any moment three IGBTs will be in ON state. In 120 degrees mode, one IGBT will be conducting for 120 degrees and at any moment two switches will be in ON state.
Let me try to number those IGBTs in the figure. The top IGBT in the first leg be numbered '1'. The bottom one in 3rd leg is '2', 2nd leg top one is '3', 1st leg bottom one '4', 3rd leg top one '5' and 2nd leg bottom one '6'. Oops! 😐 Hope its clear.
Here goes the firing sequence. In 180 degrees mode, each IGBT has to be kept ON for 180 degrees. IGBTs are switched on sequentially at every 60 degrees. Let switch 1 (s1) be fired at 0 degree. Then at 60 degrees fire S2; again after another 60 degrees fire S3. After another 60 degrees s1 is switched OFF (it completes 180 degrees conduction by this time) and s4 is turned on. This cycle continues.
In 120 degrees conduction mode, the very same thing happens except that each IGBT is turned ON only for 120 degrees. By the way, these are purely theoretical. In practise, the actual timing of switching ON and OFF of the switches will be a bit different. Other factors in the circuit are also considered when deciding the actual firing pulse width.
I made it a bit too much complicated I guess 😐Are you sure? This action cannot be undone. -
Member • Feb 27, 2013
Thanks #-Link-Snipped-# for opening my eyes I didn't think this wayAre you sure? This action cannot be undone. -
Member • Feb 27, 2013
#-Link-Snipped-# ..thanks a lot for making it clear..
#-Link-Snipped-# 😀
#-Link-Snipped-# yes sir..😀Are you sure? This action cannot be undone. -
Member • Feb 28, 2013
@#-Link-Snipped-#
its good to understood,but if it comes to implementation on softwares it may get variations. if it is matlab,then it is easy to sort out because the option to get triggering of IGBT is possible using pulse generator,..but in other platforms it may be happens but good for going lal's concept in matlab is pretty good..Are you sure? This action cannot be undone. -
Member • Feb 28, 2013
Whichever software you use or whichever trigger you use or whichever pulse generator you use, the order in which IGBTs are triggerd has to be right. And the pulse widths define the frequency of output!Are you sure? This action cannot be undone. -
Member • Mar 1, 2013
yes exactly lal its depends on pulsewidths to trigger the gate..Are you sure? This action cannot be undone.