Three phase full wave controlled rectifier with TCA785

[zaknabbit]

Hi edaboard,

I'm trying to simulate a three phase full wave controlled rectifier with three TCA785. I have some issues with the design. I saw some rectifiers with tca785 and they use three tca785 one for each phase, but they use the voltage phase-neutral, i'm trying to do this using the voltage phase-phase, and I don't know if this is possible... Another issue is the valors of the capacitors and the resistors of the tca785...

View attachment rectificador.bmp

I'm only trying the rectification. Then i'll have to isolate the ground of the control part from the ground of the power part. The control voltage is made by a voltage divisor (V11). I really don't know how to calculate the valors of the C12, C10, R9 to limitate the phase of the trigger output voltage to 120º and to make a good ramp of charge to work fine.

Thanks.

 

[zaknabbit]

I'm gonna reply to myself...

I have a problem now simulating the rectifier. I've donde all the circuit but i don't know how to solve this problem with ISIS... Any idea?

Here it is the circuit
View attachment rectifier1.1.png

And here it is the proble :bang:

 

[FvM]

I don't see immediately how you manage to get "singular matrix" errors with the circuit, usually it's about wrong netlists, e.g. floating nodes.

But I see clearly that your synchronization circuit will burn all TCA795, you are applying mains voltage between control ground and the sync inputs.

 

[zaknabbit]

Some ideas?

I fixed the matrix error setting 10Ohm resistors in the transformators output but I can't get the correct rectified signal... I'm getting crazy I don't know what to do... I've tryed everything, putting the 13 input of the tca785 to ground but nothing changed, I've tryed a lot of changes but anyone makes effect :sad:

 

[FvM]

I would like to see the corrected circuit first.

As already mentioned the synchronization circuit can't work this way. If you have common ground for the three controllers, the sync voltage must be ground referenced, too. That's easy to achieve in simulation, but should have a solution for the real hardware design as well.

 

[zaknabbit]

Hi FvM,

First of all, thanks for your attention. Okey so here it is the schematic of the corrected circuit. I have the same ground reference for the 3 tca785 and the 3 phase referende to the same ground too. If I made different power rails for the sync circuits and for the 3 phase voltage it has no effect. I forgot the ground of the isolation transformer but should be in the circuit.

View attachment 1.png