need help in inverter project

Hi everyone,
I have designed the inverter. I am using step up transformer at out put of IGBT module to increase the voltage from 110V to 230V. And using one 10uF AC capacitor in parallel with secondary of transformer.
Now I am getting proper sine wave and all. But the problem is that primary of transformer is consuming more current than expected. When I tried to sort this problem, I found that the output parallel AC capacitor is consuming about 5A and this is reflecting in to primary up to 10A.
So can any expert tell me the reason for such behavior of transformer and capacitor. Is it due to resonance?

Thanks in advance.

Regards.

Your AC capacitor acts as a AC load to the inverter.

Thanks Pico,
Yes you are right. It is acting as a load. But this capacitor is necessary for filtering and for giving proper shape to output waveform.
So can you give me any solution by which I can reduce current consumption of output capacitor.

Regards,
Spidyelectronics.

Hi buddy

I´ve had the same porblem.Some time ago I developed a half bridge inverter working at 25KHz to drive a piezoelectric crystal. I used a capacitor in the secondary exactly you have done and whith the same problem in the primary.
Look this works perfectly...Instead of use a single capacitor to filter the signal
in the secondary you" have to use " a L filter composed by a inductor in serie with the secondary and a capacitor in the other side of the inductor(the capacitor will be in parallel whit the charge).Doing that you will need a very small capacitor to achiev the same filtering, and wil reduce the current in the primary.Maths involved are very complex for my poor brain so I´ve done this experimentally.
The value of capacitor and inductor depends on the frequency you are working
but you can start with a adjustable inductor of some mH and a capacitor of some hudred nano farads.Thake care with the wire and the size of the core to make the inductor in order not to saturate it.

If you need further information feel comfortable to ask me any time, I´m here to share....and help....

Please if you know some one that could work whith Proteus(software simulation)
I would appreciate a contat

Best Regards

Francisco

Sorry for poor english.....

Thanks buddy,
It is little painful for me to introduce inductor for filtering. Instead I used higher value capacitor (in a microfarad es). It is showing effect and the current from the primary has been reduced. But the transformer is making little bit noise on load.
Regarding proteus, can you tell me your exact need, so that I may help you in a better way.

Regards,
Spidyelectronics.

Hi, just as francisco said the solution to your problem is by using low pass filter this filters the carrier frequency and allow the low frequency to pass

Hi Kabiru,
Thanks for your comment. I am still working on this issue. Parallely I also want to know how should I calculate the filter components values for DC as well as AC filter.
I am using two filters in my project. One is after rectifire. It is DC filter. It is LC filter.
And another one is at the output of the inverter, parallel to transformer secondary.
So I want to know, how can I calculate the value for the filter components. Is there any difference in inductor for both the filters?
Regards,
Spidyelectronics.

Hi Spidyelectronics,
You can use the LC low pass filter similar to the one you used at the DC side, but the value of the L and C have to be recalculated. First you have to simulate to see the output frequency spectrum without your AC filter (may be using Proteus). then note the frequency components. Then you can use another software (for example Filter solution) to design a lowpass filter then you will know the value of the L and C.

Hi all

If you are using a transformer with a center tape and two diodes to make the rectifier these are the formulas to inductor and capacitor:

L= Eout . toff/0.25Iout Eout - output voltage
toff - duty cilcle off time
Iout - specified output current

Cout=ΔI/8fΔEout ΔI= 0.25 Iout [A}
ΔEout= allowable peak to peak output voltage ripple [V]
f= operating frequency [Hz]

Try to use a low ESR capacitor to minimize ripple and loss power
that causes the capacitor to heat and reduce its life.

I have a post in this forum AT89C52VTIMER 2 NOT WORKING IN PORTEUS,
THERE IS MY PORBLEM.


Best Regards
Francisco

Hi guys,
I did some reconnections and used the 25uF capacitor. Now everything is ok regarding current. But now I am facing the problem with load regulation. As soon as put the load of 100W, the output voltage get dropped by 30V and it goes on increasing with the increase in load.
Any help will be appreciated.
Regards,
Spidyelectronics.