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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 04 2011 :  5:49:51 PM  Show Profile  Reply with Quote
http://www.edaboard.com/thread192166.html

Please click the link. (on the lower part of the discussion)


Guys, please assist me here.

I need to drive a power mosfets instead of BJT in the PWM inverter circuit (in the LINK)
What will be the change needed? I wiill be using a deep cycle batteries For approx. 1KW output.




Thanks.

juan dela cruz
Penniless INVENTOR

Edited by - JUAN DELA CRUZ on Sep 04 2011 11:52:26 PM
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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - Sep 05 2011 :  11:44:36 AM  Show Profile  Reply with Quote
I think the designer must be living in Dreamland if he thinks he can get 5KW out of that output stage.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 05 2011 :  12:27:12 PM  Show Profile  Reply with Quote
quote:
Originally posted by pebe

I think the designer must be living in Dreamland if he thinks he can get 5KW out of that output stage.



Hi Pebe its been a long time!

Yeah I think the designer used a bank of batteries! 5Kw output is impractical due to losses using BJTs.

I was looking for just approx. 1Kw output from a Deep cycle batteries.
I need to drive a Power Mosfets instead of BJT.

Do you think the driver ckt. (in the LINK) can drive power mosfets? What wiill be the adjustment needed?

Please assist me.


Thanks.

juan dela cruz
Penniless INVENTOR
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Sep 05 2011 :  12:47:36 PM  Show Profile  Reply with Quote
Most power Mosfets need a gate to source voltage of 10V to completely turn on.
That circuit has the IC powered by only 8V and it has losses so the gates of Mosfets will not be fed enough voltage.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 06 2011 :  11:46:02 AM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

Most power Mosfets need a gate to source voltage of 10V to completely turn on.
That circuit has the IC powered by only 8V and it has losses so the gates of Mosfets will not be fed enough voltage.



So, the IC should be powered by at least 12V regulated or higher to drive power mosfets?

How about the driver section.. is there any adjustment needed?




Thanks.

juan dela cruz
Penniless INVENTOR
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Sep 07 2011 :  12:07:59 AM  Show Profile  Reply with Quote
The SG3524 IC drives bipolar junction transistors very well but drives Mosfets poorly.
Complementary emitter-followers can be added to drive Mosfets but they produce additional gate voltage loss.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 08 2011 :  04:58:43 AM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

The SG3524 IC drives bipolar junction transistors very well but drives Mosfets poorly.
Complementary emitter-followers can be added to drive Mosfets but they produce additional gate voltage loss.



Ok, so complementary emitter-follower is needed in the drive section. But, using IT gate voltage loss is added? Why is that?

Can you show how it can be attach to the driver ckt?

juan dela cruz
Penniless INVENTOR
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Sep 08 2011 :  1:54:06 PM  Show Profile  Reply with Quote
A complementary emitter-follower has a 0.7V loss when it goes high and a 0.7V loss when it goes low.
The output of an SG3524 needs a pullup resistor then it can drive the complementary emitter follower. The complementary emitter follower can provide plenty of current to quickly charge and discharge the high gate capacitance of a Mosfet.

Download Attachment: complementary transistors.PNG
14.12 KB

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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 08 2011 :  6:05:26 PM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

A complementary emitter-follower has a 0.7V loss when it goes high and a 0.7V loss when it goes low.
The output of an SG3524 needs a pullup resistor then it can drive the complementary emitter follower. The complementary emitter follower can provide plenty of current to quickly charge and discharge the high gate capacitance of a Mosfet.

Download Attachment: complementary transistors.PNG
14.12 KB





Thanks audioguru but chossing the exact value of components is my problem. Please help me to choose.

1. What value of complementary emitter-follower BJTs can you suggest me to use that can be added to the Driver circuit in the link that I provided?
(do you think 2N22222A & 2N29072A will enable to drive a lot of Power mosfets to have a power output of approx. 1.5KW from a bank of deep cycle batteries ?

2. How about the pull ups resistor value? (do you think a 10K resistor will do with a 2K2 series resistor with each power mosfets?)


Thanks.

juan dela cruz
Penniless INVENTOR
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 08 2011 :  6:36:01 PM  Show Profile  Reply with Quote
@audioguru,

http://www.simplecircuitsandprojects.com/circuits/power-inverter-circuit-with-low-battery-shutdown1.html

I have found another circuit (similar to the first one but it has a low voltage shutdown circuitry) in the LINK (above) with a issue regarding with the IC supply (with 9V regulator) which is to low because of voltage loss right?

Do you think it work well esp. pull up resistor in that circuit disregarding the absents of enough voltage supply to the IC and complementary emitter-follower BJTs?


Thanks.

juan dela cruz
Penniless INVENTOR
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 10 2011 :  06:39:21 AM  Show Profile  Reply with Quote
@audioguru,

(In Addition with my Query above)

http://www.simplecircuitsandprojects.com/circuits/power-inverter-circuit-with-low-battery-shutdown1.html

I have found another circuit (similar to the first one but it has a low voltage shutdown circuitry) in the LINK (above) with a issue regarding with the IC supply (with 9V regulator) which is to low because of voltage loss right?

Do you think it work well esp. pull up resistor in that circuit disregarding the absents of enough voltage supply to the IC and complementary emitter-follower BJTs?


Thanks.

juan dela cruz
Penniless INVENTOR
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pebe
Nobel Prize Winner

United Kingdom
1078 Posts

Posted - Sep 10 2011 :  11:31:54 AM  Show Profile  Reply with Quote
quote:
Originally posted by JUAN DELA CRUZ

@audioguru,

(In Addition with my Query above)

http://www.simplecircuitsandprojects.com/circuits/power-inverter-circuit-with-low-battery-shutdown1.html

I have found another circuit (similar to the first one but it has a low voltage shutdown circuitry) in the LINK (above) with a issue regarding with the IC supply (with 9V regulator) which is to low because of voltage loss right?

Do you think it work well esp. pull up resistor in that circuit disregarding the absents of enough voltage supply to the IC and complementary emitter-follower BJTs?


Thanks.


Juan, you have been a long time developing your inverter.
I reckon that by the time you get it finished, your area will be well served by a mains electricity supply powered by a nuclear reactor.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 12 2011 :  05:59:05 AM  Show Profile  Reply with Quote
quote:
Originally posted by pebe

quote:
Originally posted by JUAN DELA CRUZ

@audioguru,

(In Addition with my Query above)

http://www.simplecircuitsandprojects.com/circuits/power-inverter-circuit-with-low-battery-shutdown1.html

I have found another circuit (similar to the first one but it has a low voltage shutdown circuitry) in the LINK (above) with a issue regarding with the IC supply (with 9V regulator) which is to low because of voltage loss right?

Do you think it work well esp. pull up resistor in that circuit disregarding the absents of enough voltage supply to the IC and complementary emitter-follower BJTs?


Thanks.


Juan, you have been a long time developing your inverter.
I reckon that by the time you get it finished, your area will be well served by a mains electricity supply powered by a nuclear reactor.



LOL!!! Well Its been a habit for me building a power inverter to power appliances from batteries.

Due to component availability I desided to build again but now using PWM IC with feedback to ensure regulation.

But, I have some difficulties choosing the right components needed. I need to convert the circuit HERE: (http://www.edaboard.com/thread192166.html) I need to drive POWER MOSFETs instead BJTs. I need to include complementary emitter-follower BJTs to drive POWER Mosfets to have an OUTPUT of approx. 1.5KW from bank of Deep Cycle Batteries. (do you think 2N2222 & 2N2907 will do??? )

I need also to choose the right value of PULL UP RESISTOR needed to drive the complementary emitter-follower BJTs from SG3524 IC.



Please assist me here...

Thanks.

Edited by - JUAN DELA CRUZ on Sep 12 2011 06:03:32 AM
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audioguru
Nobel Prize Winner

Canada
4214 Posts

Posted - Sep 12 2011 :  11:57:14 AM  Show Profile  Reply with Quote
quote:
Originally posted by JUAN DELA CRUZ

@audioguru,

http://www.simplecircuitsandprojects.com/circuits/power-inverter-circuit-with-low-battery-shutdown1.html

I have found another circuit (similar to the first one but it has a low voltage shutdown circuitry) in the LINK (above) with a issue regarding with the IC supply (with 9V regulator) which is to low because of voltage loss right?

Do you think it work well esp. pull up resistor in that circuit disregarding the absents of enough voltage supply to the IC and complementary emitter-follower BJTs?

The circuit has many things wrong:
1) The gates of the Mosfets get only 6V instead of 10V. Then they might only partially turn on and get extremely hot.
2) With two 2.2k resistors in series turning on each Mosfet then they turn on very slowly (because they have a high capacitance) which causes them to get very hot.
3) The 10k resistor to ground on each side in series with the 2.2k gate resistor for each Mosfet turn them off extremely slowly which causes them to get extremely hot.
4) The designer has the LED connected backwards.
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JUAN DELA CRUZ
Mad Scientist

Philippines
476 Posts

Posted - Sep 13 2011 :  01:54:35 AM  Show Profile  Reply with Quote
quote:
Originally posted by audioguru

quote:
Originally posted by JUAN DELA CRUZ



The circuit has many things wrong:
1) The gates of the Mosfets get only 6V instead of 10V. Then they might only partially turn on and get extremely hot.
2) With two 2.2k resistors in series turning on each Mosfet then they turn on very slowly (because they have a high capacitance) which causes them to get very hot.
3) The 10k resistor to ground on each side in series with the 2.2k gate resistor for each Mosfet turn them off extremely slowly which causes them to get extremely hot.
4) The designer has the LED connected backwards.



How about in this circuit: (http://www.edaboard.com/thread192166.html)

quote:
Originally posted by audioguru

A complementary emitter-follower has a 0.7V loss when it goes high and a 0.7V loss when it goes low.
The output of an SG3524 needs a pullup resistor then it can drive the complementary emitter follower. The complementary emitter follower can provide plenty of current to quickly charge and discharge the high gate capacitance of a Mosfet.

Download Attachment: complementary transistors.PNG
14.12áKB





Thanks audioguru but chossing the exact value of components is my problem. Please help me to choose.

1. What value of complementary emitter-follower BJTs can you suggest me to use that can be added to the Driver circuit in the link that I provided?
(do you think 2N22222A & 2N29072A will enable to drive a lot of Power mosfets to have a power output of approx. 1.5KW from a bank of deep cycle batteries ?

2. How about the pull ups resistor value?

Thanks.

juan dela cruz
Penniless INVENTOR
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