Full bridge circuit help

Krej · 10th July 2008, 12:13 PM

Hello,
I am thinking of making an inverter with 300w power.
I have made the first step up stage from 12v to 310v. For the full bridge circuit, i want 2 use gate transformer to drive the 4 mosfets.
Can someone help me in constructing the gate trafo...the turns ratio?
Since, it is 50hz conversion, trafo has 2 b iron core, right?

areza · 10th July 2008, 12:38 PM

use opto instead transformer for 50/60hz, or use discrete transistor driver or use one of the hi/lo bridge ic (ir2110)
Search the forum for power stage.pdf , its a nice h-bridge,

Krej · 10th July 2008, 02:54 PM

Are you sure a 2.2u cap can keep the hi side turned on for 10ms?

areza · 10th July 2008, 04:14 PM

may be 2.2u is enough , most important is layout , i had to layout few times to get it working with 20%-30% duty cycle, u may need to lower the voltage to 250-260v , also need to use A44 npn as well if u keep the voltage to 310v,

S.G. Mahbub · 10th July 2008, 06:39 PM

Dear krej,

Not 2.2u, even 500u cap will not be able to keep the high side on for 10 ms, making virtual ground. Your all test and trial will be futile.
IR2110 is for high frequency, not for Low frequency.
It is safe and sound to use driver transformer. When you provide 12v to sg3525, the output will be 6 volt and you made a 1:2 normal linear transformer, so that you get 10v - 12v output in the driver transformer for mosfet gate drive.

Transformer Winding:

180 turn in primary side with s.w.g. 34 wire for 6v input and 4x secondary output should be 400 turn each with same or s.g.36 size wire. It would be a small silicon sheet linear transformer. You must mark start and finish of primary and all the secondaries so that you can connect those 4 secondaries for 2 high sides and 2 low side in such a way that when 1high side and 1 low side is on, then other high side and low side is off and vice versa. If both the high side is on simultaneously, then you will loose all the mosfets as they will be shorted and destroyed.
Other than transformer, you can use PVI safely for full bridge circuit.
Thanks.

____________________________________________
IDEAS ARE MONEY IF THEY CAN BE USED ON GROUND.
বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ।

Krej · 11th July 2008, 08:17 AM

Thanks for the info.

10th July 2008, 12:13 PM	#1
Krej diyAudio Member Join Date: Jul 2008	Full bridge circuit help Hello, I am thinking of making an inverter with 300w power. I have made the first step up stage from 12v to 310v. For the full bridge circuit, i want 2 use gate transformer to drive the 4 mosfets. Can someone help me in constructing the gate trafo...the turns ratio? Since, it is 50hz conversion, trafo has 2 b iron core, right?

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10th July 2008, 12:38 PM	#2
areza diyAudio Member Join Date: Jun 2007	use opto instead transformer for 50/60hz, or use discrete transistor driver or use one of the hi/lo bridge ic (ir2110) Search the forum for power stage.pdf , its a nice h-bridge,

10th July 2008, 02:54 PM	#3
Krej diyAudio Member Join Date: Jul 2008	Are you sure a 2.2u cap can keep the hi side turned on for 10ms?

10th July 2008, 04:14 PM	#4
areza diyAudio Member Join Date: Jun 2007	may be 2.2u is enough , most important is layout , i had to layout few times to get it working with 20%-30% duty cycle, u may need to lower the voltage to 250-260v , also need to use A44 npn as well if u keep the voltage to 310v,

10th July 2008, 06:39 PM	#5
S.G. Mahbub diyAudio Member Join Date: May 2008	Dear krej, Not 2.2u, even 500u cap will not be able to keep the high side on for 10 ms, making virtual ground. Your all test and trial will be futile. IR2110 is for high frequency, not for Low frequency. It is safe and sound to use driver transformer. When you provide 12v to sg3525, the output will be 6 volt and you made a 1:2 normal linear transformer, so that you get 10v - 12v output in the driver transformer for mosfet gate drive. Transformer Winding: 180 turn in primary side with s.w.g. 34 wire for 6v input and 4x secondary output should be 400 turn each with same or s.g.36 size wire. It would be a small silicon sheet linear transformer. You must mark start and finish of primary and all the secondaries so that you can connect those 4 secondaries for 2 high sides and 2 low side in such a way that when 1high side and 1 low side is on, then other high side and low side is off and vice versa. If both the high side is on simultaneously, then you will loose all the mosfets as they will be shorted and destroyed. Other than transformer, you can use PVI safely for full bridge circuit. Thanks. ____________________________________________ IDEAS ARE MONEY IF THEY CAN BE USED ON GROUND. বাস্তবে ব্যবহারযোগ্য চিন্তাধারাই মানুষের প্রকৃত সম্পদ।

11th July 2008, 08:17 AM	#6
Krej diyAudio Member Join Date: Jul 2008	Thanks for the info.

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