Isis proteus help

[aamir shabbir]

Hi guyz...........i am facing a problem is proteus how can i check the waveform across a resistor or any component using oscilloscope since the scope just has terminals channels A,B,C,D there is no ground it always gives the signal with respect to ground how can i use it to check the signal across a component?

 

[Misterbenn]

differential scope probe would be the standard method.

What kind of common mode voltage rejection are you looking for?

 

[Ian Rogers]

Not sure why you need to do this... Can you show why you need to see the waveform with reference other than gnd??

 

[aamir shabbir]

this is a sine wave generation by atmega controller check the image i ve connected the scope on the capacitor as the other leg is already ground but in the case of bridge the i want to check the voltage across capacitor only how will i do that?

 

[Ian Rogers]

? The cap is grounded!! Surely that's what you are reading now?

If you mean the voltage across the resistor, then just put a scope lead on the micro pin.. Then you can work it out..

 

[aamir shabbir]

where is the resistor in the circuit ??..............and in the circuit of bridge i want to read voltage aross capacitor not with ground

 

[Ian Rogers]

Sorry..I meant the inductor... Your circuit shows the wrong cap then....

I see what you mean.. remember when these fets are fully on there will be nearly be 12v and 0v on each cycle

 

[Misterbenn]

Ian, he is trying to measure the voltage across the capacitor connected to the H-bridge, not the one at the PIC output.

If your scope can be battery powered, quite a lot of them can be these days, then unplug it from the mains and you remove the ground path; the scope will be floating. You can then simply connect your probe across the capacitor. The only other way is with a diff probe.

By the way if you were to implement this in practise you would have big problems with shoot through. The turn-off time of the IGBTs is NOT instant.

 

[Ian Rogers]

He is on ISIS simulation.... The scope hasn't got any physical connections to earth.... I know now the cap is the one on the hbridge but ISIS can't do what he's asking...

 

[Misterbenn]

Ah sorry, I had assumed he was trying a real world measurement.

I'm not familiar with ISIS, it doesn't have a differential probe / voltage probe?

Connect an dual rail, unity gain opamp across the capacitor, the output can then be measured with respect to ground.

A 1:1 transformer would do the job as well, could be put in place of the inductor if you give it a primary inductance equal to that of the inductor.

 

[Ian Rogers]

Ive been playing... Try to connect two probes either side of the cap... Once the simulation is running on the A control there is an A+B selection... Try to see if this is what you need...

 

[aamir shabbir]

actually friend i want to make a pure sinewave inverter using pwm techinique i have done a part of it i ve made out the reference sine wave from controller and passing it through LC filter i get a pure sine wave i want to use those pulses and increase the output to 220V and about 5A output current means 1KW inverter what should be the next step after making the reference sine wave i was using a full bridge mos circuit for it please guide in detail

 

[Ian Rogers]

Your question is best directed to the HV forum... I have never made an invertor.. Once you get your sinewave spot on. I would then see if another member can help you crank up the voltage...

 

[aamir shabbir]

i have done it i have made the sine wave from controller i just want to increse the power now what technique should be used for it

 

[Misterbenn]

you'll need to put it through a transformer with a sufficient turns ratio.

What are you using as a power source?

 

[aamir shabbir]

i will use a 12V battery the bridge circuit will take the pwm as gate input and then switch on the pwm and then i have to make the power to 1KW what should i do ?

 

[Ian Rogers]

aamir... I've closed this thread.. Carry on your discussions here please

https://www.electro-tech-online.com/threads/sine-wave-inverter.139598/