[SOLVED] Pic 16f876a Pure Sinewave inverter

[daniello_85]

Hi Californiajoe

I put the resistor 1Kohm connected between gate and source. Also I made photos of the output sine wave with and without load. The problem is the same

Regards

 

[Californiajoe]

It looks like positive wave is cut a little. Can you meassure the suply voltage on TLP250s with load. Be carefull with GND of an instrument.

Regards

 

[daniello_85]

Do you think that peak between positive sine half wave and negative sine half wave is important?I think that it's very important and this is my problem. Do you appear this peak in your inverter? The value with load 50W is:
U3 -> (11.38V-11.40V).
U4 -> (11.38V-11.40V).
U5 -> 11.63V.
U6 -> 11.63V.

Note: The measure have been between Pin 8-Pin 5 TLP250. The voltage A-B is the 8.54Vac
Regards

 

[Californiajoe]

I think so. You have diferent type of diodes. They should be SS34.
I thing suplying voltage for TLP250 should be equal for all of them, only in that case you will have equal positive and negative sine wave.
Also capacitors c19 and c20 should be tantal (the best as possible).

Regards

 

[daniello_85]

I'm going to do several checks about my inverter. I will try improve the layout.;-);-)
I changed the diode because the Electrical Characteristics is similar.


Regards

 

[Californiajoe]

Take a look in to my Output PCB (picture and plan is few pages back), pins of mosfets are pushed aside to get stronger PCB connections.
Don't forget to check capacitors.

Regards

 

[daniello_85]

Californiajoe i'm going to build your output inverter. This is the file?How have you solder the MOSFETs. The pins is very near!

Regards!!:grin:

 

[Californiajoe]

Take a look into component side PCB, there is enough space beetween them. Don't forget to put tiny isolator between mosfet and cooler.

Regards

 

[jami007]

also you need to check the temperature of the mosfets, as i said earlier if the mosfet heatup significantly its a builtin property that the output go on decreasing and at a point its shuts down to prevent damage.....

---------- Post added at 17:48 ---------- Previous post was at 17:29 ----------

also check the bootstrap supply for 2 tlps (connect according to taner's diagram), if the bootstrap supply connection to tlp's are wrong this type of problem arise.....so check your supply to TLP's according to taners schematic.....also 8 mosfets are used in parallel to support large current (500W case) so for low power i think 4 of them are enough.

 

[daniello_85]

Hi Californijoe & jami007
I've done new layout about stage power, the design is Californiajoe's layout. My voltage drop out 30V when I put load 50W. But i want to say that I don't have feedback with PIC16F876A. I've put trimmers. My problem is when i connect the feeback connection my inverter it doesn't work.

Note: In the photo It don't appear the heatsink, i must put them. Also i want to say that my inverter is design over protoboard (breadboard)

Best regards
Daniel;-)

 

[Californiajoe]

Well, PIC16F876A MUST have feedback, but those signals must be correct. I described procedure how to "help" PIC16F876A to start to workfew pages back, it is something about b/a signal (resistor over C35 i think). Find those page and test it.

Regards

Here it is post #512:
One more thing: I just noticed that pin 2 of 16f876a had to high voltage on it (over 4V) and there was no PWM and A/B signals from MCU. After connection of the resistor ( 1k ) from pin 2 and GND inverter started to run.

regards

 

[jami007]

gentleman use sinks before test otherwise u'll destroy your mosfets, ensure all feedbacks and enjoy......the most difficult job in it is ensuring proper feedback.....

best regards

 

[daniello_85]

Ok! A last question, do you think that all feedback is necesary to ensure proper work of the inverter?I want to say that my problem happen because i don't have the feedback in my PIC16F876A, that is to say, my voltage drop because i don't feedback to my PIC16F876A and it can't boost the output voltage.

Thank you very much!;-);-)

 

[Californiajoe]

It's been said many times, for proper work of the inverter you must have proprer feedback. MCU must sense drop of the voltage of the output transformer, It must sense load on the output and so on, and so on.
Few rules, which should be considered:
1.Make sure everything is connected as it should be.
2.Proper cooling of output mosfets
3.NTC resistor termically connected to the cooler (mosfets)
4.Measuring of all analog signals which are connected to MCU, make sure to be those signals in correct range for proper work of the inverter
5.In case some of them is not correct, replace it with trimer pot. temporarily.
6.Remoove helping trimmers pot. one by one with real signals
Thats all I can remember at the momment. All those signals must be balanced between each other to get proper work of the inverter.

Happy new year to all of you!

Regards

 

[daniello_85]

Ok Californiajoe!

Happy new year everybody!!:grin::grin::grin:

 

[jami007]

Ok! A last question, do you think that all feedback is necesary to ensure proper work of the inverter?I want to say that my problem happen because i don't have the feedback in my PIC16F876A, that is to say, my voltage drop because i don't feedback to my PIC16F876A and it can't boost the output voltage.

Thank you very much!;-);-)

Daniel go to the page

https://www.edaboard.com/threads/96053/

download source code folder named [source_code_1953.zip] from my uploads, here in this folder i uploaded all source codes including one in which we need no b/a feeback so you can try this code too.

Happy New Year

 

[daniello_85]

Hi jami007 & Californijoe
I tried your code jami007 and my problem is the same. In your inverter when you connect load 50w, the output voltage is 230V?Can you try it? I will feedback all connection, i will comment my results.
Regards

 

[jami007]

did you try heat sinks with sink paste? if overheating is not the cause of problem, then check bootstrap supply connections to tlps, also post the results with inductive load

Best Regards

 

[Californiajoe]

First connect all feedback signals to the MCU, then you should do tests.

Regards

 

[daniello_85]

Hi Californiajoe and jami007. I connected all feedback signals to the MCU, but my inverter it doesn't work. The voltage are:
V_out=2.51V
curr_h= 2.53V
curr_l=2.51V
volt= 4.4V
Stdby=0.88V
b/a= 2.45V. I've connected a resistor 1K between b/a - GND, but my inverter it doesn't work.

After I connected trimmer for "curr_h/l" & "V_out" and my inverter started to run, also the b/a=0.33V. Thank you for your help Californiajoe & jami007!!
Best regards!!