[SOLVED] Pic 16f876a Pure Sinewave inverter

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Hoi Pierre, you said:
- taken out U1,2,3 and 4, but you do mean: U3,4,5 and 6, right?
- Lamps in series between gnd and +U, and the midpoint connected to B, is ok.
=Yes, test with pos. voltage and a serie resistor on the Fet gates (R41 and R43) will switch the upper (Q1 lamp) off, then on R45 and R47, that should switch the lower (Q5 lamp) off. You might connect a 10k resistor from gate to source (or R41 to B), so that the Fet gate is not floating during test.

Warning: Do not switch Q1 and Q5 Fet on at the same time, because one of them will leave this Earth then. A temporary series resistor (1 or 2 ohm) or fuse in the +U line will prevent that.
Good luck, At.
 

At wrote

Test +10V on R45 switch Q5 but Test +10V on R41 don't switch Q1.
I use new FET's and my problem is also the same . The upper don't switch .
What do you think about this ?
Pierre
 
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doc007 said:
Test +10V on R45 switch Q5 but Test +10V on R41 don't switch Q1.
Click to expand...
Hallo Pierre, does not sound logic.
Instead of 10v use +U or a higher voltage (use an extra battery on top of +U). An extra 4 or 5 volts should be enough.
What do you mean with "don't switch"? Don't you see any difference in light intensity of the lamps? What kind of lamps do you use?
Are the gate's of the upper and lower Fet's connected to their sources with 10K or so?
At.
 
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HI aT
excuse me for my incompetence.
1) Only the gate of the upper Fet Q1 was connected to his source with 10K.(R41 to B)
10V on R45 switched off the lower (Q5 lamp ) .
10V on R41 doen't switch off the upper ( Q1 lamp ). Only when I pick 10 V on R41 the lamp is blinking once and believe on.


2)Then I have linked the gate of the lower Fet Q5 with his source with 10K.(R45 to GND)
10V on R45 doesn't switch off the lower (Q5 lamp ) off. Blinking once and believe on.
Same result with the upper (Q1 lamp)

3) I have taken away the link (gate Q1 with his source )
10V on R45 doesn't switch off the lower (Q5 lamp ) off ( blinking once ) but
10V on R41 switched off the upper (Q1 lamp )

It seems that the link beetwen the gates and their respective sources by 10k prevents the switch.

Can I test the functioning without the two links ( G-S) ?
Pierre
 
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doc007 said:
It seems that the link beetwen the gates and their respective sources by 10k prevents the switch. Can I test the functioning without the two links ( G-S) ?
Pierre
Click to expand...
Hallo Pierre,
I made a setup and show you a schematic, see the 220ohm resistor connected to the lower or upper Fet, the 10k R's should stay in place.
The Vb used is 6v for the fotographs (lower lamp intension), but 12v worked too ofcourse.
The 10k R's function is to prevent the not used gate from floating (and accumulating any charge they like, and maybe turn on). We do not want the two Fets on at the same time. If it do happens, the 1ohm resistor in the schematic will take the heat and burns out (like a fuse).
Greetings At.
 

Hello At
Thanks for your schema . They are very nice.

There was a big misunderstanding of my part. I have not understand that to switch when the 10 K are in place I must keep the contact of +V on the gate.
My short contact explain the blinking.
Q1 and Q5 switch
I will test Q3 Q7.
Can I then test my circuit with U3 U4 U5 and U6 without the 10 K protection ?
Pierre
 

hi pierre and AT
I cant find irl3803 and(IRL****) in my country,what i must do? similer part from IRF series?
tnx
 

Hello At,
When I accomplish your assemblage, the two FET's switch wirthout any problem.

on the contrary when I test Q1 and Q5 on the schema of Taner the upper doesn't switch . ( The upper lamp keep on when I pick The Gate of Q1 )
It's illogical but ?????
I double-checked one more time the circuit and all seems normal without wrong contact .
Thanks for your help
Pierre
 

doc007 said:
when I test Q1 and Q5 on the schema of Taner the upper doesn't switch.
Click to expand...
Hello Pierre. Instead of 10v try +U or a higher voltage (use an extra battery on top of +U).
An extra 4 or 5 volts should be enough. Tell us how many volts extra you need (on the gate) to get it switched on.
If you test via U3,4,5 and 6, the gate voltage for the upper Fet's will be pumped-up to above +U if you alternate the input on 4 and 7.
To do that manually, connect 7 to gnd and connect 4 via 470ohm to either +5 or -5 volts (ca. 4 to 6v).
The 10k R's are not neccesary than, the two optocouplers insure that only one of the two Fet's will be active at one point in time.
If that all works, you can try to connect an alternating voltage (50Hz) of about 5v to points 4 and 7 (via an R), and the output lamps should then light up equally.
Then test the other half (A) of the bridge. If that's ok test the full bridge, connect 4 and 7 parallel to 12 and 9, take One lamp and connect it between A and B.
With 50Hz on 4-7 and 12-9, it should not flicker, but light-up brightly with 50Hz.
It burns on 12vAC t/t square wave. If you connect a diode in series with the lamp it will visually flicker at 25 Hz.
If nothing happens at the output, check that at the input, 4 is connected to 12, and 7 to 9.
After that it's time to connect a transformer between A and B, check the battery current, then go further with U11 connected... and so on (to finally get a pwm simulated sine wave which suits your trafo better and causes less noise).
Greetings At.

Added after 32 minutes:

farshadtitanic said:
I cant find irl3803 and(IRL****) in my country,what i must do? similer part from IRF series? tnx
Click to expand...
Probably IRL3803 is choosen for its low Rds-on and high current throughput (>100A). If you need about 500 or 600Watt output, then about only 50A is drawn from the 12v battery. So search for the type that suits you. And don't forget that the transformer is an important item too.
At.
 

Hello At

At wrote
Instead of 10v try +U or a higher voltage (use an extra battery on top of +U). An extra 4 or 5 volts should be enough. Tell us how many volts extra you need (on the gate) to get them switched on.
Click to expand...

With +U on the gate the upper Fet switched on ( The upper lamp however is not completely off).
Pierre
 

Ok, The Fet is an analog thing, you need more gate voltage to switch it 100% on.
At.
 

Hi
I have now tested Q1, Q5 and Q3, Q7 via U3,U5,and U4,U6------> the upper fet's Q1 and Q3 doesn't switched on.
How can do to have more gate voltage ?
Pierre
 

doc007 said:
Hi
I have now tested Q1, Q5 and Q3, Q7 via U3,U5,and U4,U6------> the upper fet's Q1 and Q3 doesn't switched on. How can do to have more gate voltage ?
Pierre
Click to expand...
- You did not report how much extra voltage you needed, in the test before.
- And here you don't specify How you test, (static or dynamic).

The bootstrap circuit is mentioned twice, which will boost the voltage for the upper fet's, it will function in dynamic mode.
But you should test first staticly (I can't do it for you, I don't have the IRL3803 fet's.)
Yesterday, or 4 posts back:
Hello Pierre. Instead of 10v try +U or a higher voltage (use an extra battery on top of +U). An extra 4 or 5 volts should be enough. Tell us how many volts extra you need (on the gate) to get it switched on.
Click to expand...
3x 1,5v batt. makes 4,5v extra, to feed your 220ohm resistor.
At.
 

Hi At

At wrote
- You did not report how much extra voltage you needed, in the test before.
- And here you don't specify How you test, (static or dynamic).
Click to expand...

I need 1V extra voltage on top of +U to switch the upper FETs


Q1, Q5 via U3,U5 are tested static
by connecting 7 to gnd and 4 via 470ohm to+5 alternately

Q3, Q7 via U4,U6 are tested static
by connecting 9 to gnd and 12 via 470ohm to+5 alternately

Pierre
 

doc007 said:
Hi At
I need 1V extra voltage on top of +U to switch the upper FETs
//
by connecting 7 to gnd and 4 via 470ohm to+5 alternately
//
by connecting 9 to gnd and 12 via 470ohm to+5 alternately
Pierre
Click to expand...
Ok, thank you, 1volt more will be easy supplied by the bootstrap circuit.
The two lines about "alternately" I don't understand.
Read again the post from this morning. Alternating voltage means positive and negative, not 5v on or off.
A real alternating voltage (from a 50Hz transformer) will do that dynamicly.

Connect AC as outlined earlier and so that when the applied voltage goes positive, one half of the bridge conducts in the upperpart and the other half in the lowerpart and vice versa. So take 7 and 9 together as one pole, and 4 via 470ohm and 12 via 470ohm, together as the other. Then apply AC. Load on A/B.
At.
 

farshadtitanic said:
what is the N1/N2 of 2 transformer?
Click to expand...
Sorry can't help you with that, I'm not the designer of this circuit. Contact the original poster.
 

farshadtitanic said:
tanks AT for your help,
what is the N1/N2 of 2 transformer?
Click to expand...

farshadtitanic

By data in the schematics the Transformer ratio seems to be 28.75 if the values of Vp and Vs are taken as 8 and 230V respectively.

furthermore you can derive other basic calculations by the following calculations:-

Turns Ratio
TR = Ns / Np

where TR = turns ratio; Ns = # of turns in secondary winding; Np = # of turns in primary winding.

Voltage / Current Ratios
Ns / Np = Vs / Vp = Ip / Is

Vs = TR x Vp

Is = Ip / TR
where Vs = voltage in secondary winding; Vp = voltage in primary winding; Is =current in secondary winding; Ip = current in primary winding; Ns = # of turns in secondary winding; Np = # of turns in primary winding

Impedance Ratio
TR = sqrt (Zs / Zp)

where TR = turns ratio; Zp = impedance reflected into the primary side with a secondary load of Zs

With best regards,

Ghazali Zuberi
 

Hello At

At wrote
If you test via U3,4,5 and 6, the gate voltage for the upper Fet's will be pumped-up to above +U if you alternate the input on 4 and 7.
To do that manually, connect 7 to gnd and connect 4 via 470ohm to either +5 or -5 volts (ca. 4 to 6v).
Click to expand...
I have make this test : when +5V on 4 the under Fet has switched, but when -5 V on 4 the upper Fet has not switched
Pierre
 

doc007 said:
when +5V on 4 the under Fet has switched, but when -5 V on 4 the upper Fet has not switched
Pierre
Click to expand...
Hello Pierre,
You have to change the +/-/+/- voltage fast, (very fast) and the upper fet should at least flash then.
If not, try a connection to a transformer, use a serial resistor so that the current will be 10 to 20mA.
If that still not succeeds we have to sort it out further.
At.
 

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