how to do sine PWM generation in orcad pspice

Hi All,

I am trying to design a PWM inverter in Orcad PSPICE where i am using a Vpulse source from library to generate MOSFET triggering pulses for H-bridge and it works fine for square waves.

But i ponder if i want to generate sinusoidal pwm to drive the h-bridge how can i accomplish it in orcad pspice and drive the mosfets accordingly.



I figured out that sinusoidal pwm is generated by comparing a sinusoidal wave with triangular wave.Is there any way we could simulate sine pwm in orcad pspice and drive the h bridge accordingly different switching topologies.?

I would appreciate any help or suggestions that will help me to achieve my intended purpose of making prototype of sine wave pwm generation like as mentioned above in picture using orcad pspice.


Thank You for your time

Aron91

I think that can be easily done using 555 timer circuit.
555 timer is available in somewhere in orcad libraries.
Just do web search - "pwm 555 timer" and you'll get lot of links showing how to achieve this.

Try PWL source format.

A straightforward solution would use a ramp generator (vpulse), a sine generator (vsin) and a comparator, either a real IC or a simple behavioral one.

Thanks a lot people.
ok ill try those items.But there is no comparator by default in orcad pspice for comparing triangle wave and sinusoidal wave ?.Ill try the above methods soon.

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@Fvm Thank you very much.i'm trying exactly the same steps.Can you suggest a convenient comparator that could be used here.Any available library file would be fine.Thanks again

Hi FvM
Im using orcad Capture lite 16.5
orcad AD lite too student version.

i tried my hand at Glimit from ABM Library but it seem to be a single input limiter that limits the voltage between two threshold voltages.Can you tell me how you tried it using Glimit comparing sine wave and triangular wave.

Meanwhile i would try using other comparators.Do suggest if any good option for comparator is available.

Thanks

Î'm not presently working with PSpice ans don't know which version you have. I used GLIMIT from the analog behavioral modelling library as comparator. But any sufficiently fast real or ideal OP or comparator can be used.

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Yes, there will be a subtractor in front of GLIMIT.

Hi FvM thanks again I tried out that yesterday and was successful in developing the simulation.
I'll post the details here along with the image of schematic so that i could be helpful for anyone in near future.
S/w - pspice orcad capture 16.5

Steps:

1.Select these parts triangle wave generator,sine wave generator,GLIMIT from ABM library and difference operator from the same.

2.Set the sine wave frequency @50/60 or as u like so the time period will be 20 ms.

3.Now the triangular wave form will be doing the job of sampling and set it's frequency around a point such that you will be having more samples for pwm.I kept it's time period at .2 ms.

4.Save the simulation profile and run it

@Fvm i have one more question for you. Now i have sine pwm for +ve cycle of sine wave and it can be used to drive say one bridge(or the mosfet pair conducting in +ve cycle).If i take the complementary of this +ve sine pwm and fed it to the bridge doing the job for -ve cycle it should deliver sine wave at the h bridge output right?

Is that the correct way of doing so?

Perfecting the H bridge inverter in Pspice simulation

Hello guys

I have been trying to build a sine wave inverter and i chose to simulate first to get the clarity and proof of idea.
So i end up using P spice simulations and learnt how to generate a Sine pulse width modulation using it's elements

STEP1
The Sine PWM generated


Then i chose IRFZ45 Mosfets as the block for the H bridge and started simulating the model using Sine PWM.
But i have some problems or doubts regarding the procedure and i would like your suggestions to perfect the H bridge model if possible using the same Mosfet.


STEP2
Here when i did the simulation using 180 degree phase shifted PWM to the H bridge i got an output like this.The following are the corresponding schematic and output


Output 1




But when only one half bridge is driven using 5 V and the other bridge is kept idle i got an output like this peaking till 30 V.For me this is almost similar to Sine wave half cycle. How could be the 'Output 1' be like that and what should be done to get a +ve cycle like 'Output 2' and it's inverted output
Output 2


And finally when i took voltage across the R Load i got the output like this one
Output 3

Is'nt it the output should be like this with +60 V and -60V with a maximum tolerance of 10%.That's what the theory about H bridge implies.But i'm not able to get an out put as so.
What should i include or edit inside the circuit so that i can get a near perfect working H bridge in simulation.I trust i might have missed Dead time but i have no clue how to implement it.Please do point out if any contrasting difference or mistake is found in this Simulation model.

It would be extremely helpful if you can help me to attain my desired output or give valuable suggestions.I will be extremely grateful for any such gestures.

Thanks again for your valuable time

Regards
Aron91