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Current single phase rectifier

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FreeRiderCz

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Pulse rectifier - single phase and for current and voltage

Hello im currently trying to simulate single phase current rectifier in OrCad 16.6 and i think im doing something wrong, can someone more experienced than me point out what is wrong?

Schematics are here:

Qfae.png

Every help would be really apreciated... thx a lot
 
Last edited by a moderator:

Re: Pulse rectifier - single phase and for current and voltage

Actually i move a little... is this correct function for single phase current rectifier?

schematics:
single phase current.png

output:
single current 2.png

So can someone tell me this is proper function? Im not sure why i got on output only around 0,5V but i think that output voltage curve correspond with output i got in theory....is that correct?
 

Re: Pulse rectifier - single phase and for current and voltage

I don't understand what a current rectifier is or what you are trying to do. :???:
 

Re: Pulse rectifier - single phase and for current and voltage

Your schematic has a load circuit different from the paper. It doesn't make sense to me at first sight.

The paper is describing a boost mode PFC chopper with voltage output. According to the given definition it's a "voltage type" rectifier, output voltage is always higher than the input voltage. The latter is commanded by the antiparallel IGBT diodes, which are confusingly hidden in your schematic.

Which output and current waveforms do you expect?
 

Re: Pulse rectifier - single phase and for current and voltage

Your schematic has a load circuit different from the paper. It doesn't make sense to me at first sight.

The paper is describing a boost mode PFC chopper with voltage output. According to the given definition it's a "voltage type" rectifier, output voltage is always higher than the input voltage. The latter is commanded by the antiparallel IGBT diodes, which are confusingly hidden in your schematic.

Which output and current waveforms do you expect?

Well that was just for that guy asking about rectifiers, im using this scheme to make current single phase rectifier:

pulse current.png

and im using IGBT instead of thyristors.
 

Re: Pulse rectifier - single phase and for current and voltage

Actually i move a little... is this correct function for single phase current rectifier?

schematics:
View attachment 144684

output:
View attachment 144685

So can someone tell me this is proper function? Im not sure why i got on output only around 0,5V but i think that output voltage curve correspond with output i got in theory....is that correct?

To understand the current rectification, you must display it along with voltage during the deadtime for PWM commutation. L/R decay times and LdI/dt will create spikes that may be clamped by diodes. Schottky diodes will have more C but lower Vf.
 

Re: Pulse rectifier - single phase and for current and voltage

To understand the current rectification, you must display it along with voltage during the deadtime for PWM commutation. L/R decay times and LdI/dt will create spikes that may be clamped by diodes. Schottky diodes will have more C but lower Vf.

Is this better_ i think problem is my output voltage is really small (around 0,5V)

aaaaaa.png
 

Re: Pulse rectifier - single phase and for current and voltage

Actually i just lowered R2 (coz it was too big) and i change PWM for Z1 and Z4 (because i´ve got all 4 IGBT´s on at same time and thats why this wasnt working :-D ) so now its all right and working as intended

aaaaaaaaaaaa.png
 

Re: Pulse rectifier - single phase and for current and voltage

and im using IGBT instead of thyristors
Does't work. Unlike SCR, IGBTs have no reverse blocking capability. They are either equipped with a built-in reverse diode (APT25 has it as far I'm aware of) or they have a low reverse breakdown voltage of a few 10 volts and must be supplemented with an additional diode to protect it.

- - - Updated - - -

so now its all right and working as intended
Question is if the circuits works with real IGBT too.
 

Hello guys, im having a hard time solving problem with this simulation:

test.png

and im getting bad results on the load ( L2 and R1), coz current should be continuous, instead im having this results:

test2.png


so as you can see, current is reaching 0 and i dont know what to do to get more sinusoid result with continuous uninterupted current.... (just FYI for each IGBT -V1-V4 i put same block of PWM modulation), can someone point me out with problem here? Coz im unable to find it...
 

I checked that the PSPICE APT25GF model is missing a reverse diode, in accordance with the symbol but despite of the built-in diode in actual APT25GF part. To achieve reasonable circuit operation, it's necessary to supplement rectifier diodes, see my previous comment about reverse blocking of IGBT.

The generic PSPICE IGBT model doesn't model reverse breakdown correctly, so the simulation results are completely different from expectable real circuit behavior, either for IGBT with or without built-in diode.

I agree with SunnySkyguy that the output inductor time constant should be increased to get continuous current, but presently the circuit is behaving just unrealistically due to the reverse diode problem.
 

I checked that the PSPICE APT25GF model is missing a reverse diode, in accordance with the symbol but despite of the built-in diode in actual APT25GF part. To achieve reasonable circuit operation, it's necessary to supplement rectifier diodes, see my previous comment about reverse blocking of IGBT.

The generic PSPICE IGBT model doesn't model reverse breakdown correctly, so the simulation results are completely different from expectable real circuit behavior, either for IGBT with or without built-in diode.

I agree with SunnySkyguy that the output inductor time constant should be increased to get continuous current, but presently the circuit is behaving just unrealistically due to the reverse diode problem.

Oh i didnt noticed that this IGBT doesnt involve reverse diode, could you please suggest one which should fit better in this scheme?

and its about R/L difference on output how high T in R/L should be?
 
Last edited:

I have no exact APT25GF datasheet, I guess the real part has a reverse diode, but the PSPICE model doesn't have it. Thus you should add an external diode to your circuit.
 

Perhaps a diode in the STBR60xx-Y family will be suitable

For Load R and inductor L with T=L/R and PWM half cycle time t=x/2f must be <10x T=L/R for more continuous current. Thus PWM f/50Hz ratio must increase by ~100x or L increases by same ratio which is more expensive.

Yet too high PWM causes switch capacitance with shunt load current spikes not shown in model as well as stray capacitance.
 

hm diodes wont help, my coleague told me i´ve got wrong switching of IGBTS... im using 4 blocks (one for each) to make PWM but now im not sure if its right switching settings for this scheme.... can someone pls point out if is there something wrong with my PWM for IGBTs?
 

Well when i put diodes out, and make L = 100mH R=10ohm on output i get these results, i guess coz current single phase rectifier works only in one quadrant , then is this correct function (finaly?? :-D )

these are result for settings of U_mod=0,9 and f_mod=10kHz

Voltage on output
napětí.png

current on output
proud.png
 

Well i made a lot of progress, but still im unable to get correct results...

im using this picture from theory as my nav for switching logic,

spinaci logika 2.png

and i set up switching logic like this as seen on diagram:

spinani oprava 2.png

and my problem is - switching is just like in theory but i dont know why im getting this results on output....

results.png

i dont know how add files of my orcad simulations, if anyone interested to check it out and give me a direction on what is WRONG.... coz im totaly out of any ideas...and its driving me almost crazy...please help me guys :-(

- - - Updated - - -

im adding at least scheme with PWM modulation blocks im using

scheme 1.png
 

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