AC GrounD And DC Ground

[cranker]

My Question is that I am Taking 220V Ac And After i Rectify it , I got DC +110V And -110V
IF i Can Connect AC Ground With DC ground ????

 

[HTA]

Since the power plug could be inserted two way, the AC ground (return) is not clear and could be also be +220V. Then your DC ground would be very dangerous to touch. Or do you mean with ground the protective ground (third pole in a thhree plug AC connector?

 

[Reloadron]

As marked it would be DC Negative with respect to DC Positive.

You are rectifying a 155 volt RMS signal to DC. The capacitor will charge to 155 * 1.414 or about 220 VDC. If the cap was removed you would have 155 volts less the forward diode drops on alternate half cycles of the incoming waveform.

Can you connect AC Ground with DC Negative? Yes. You should really better explain what you are trying to do though. You don't show the source of your Ac as it a transformer secondary or mains? Mains means no isolation.

Ron

 

[crutschow]

Only if you want to blow a diode.

The bridge output must remain isolated from the input if you have no transformer.

For example, suppose you connected the output common (the point you indicated) to the (-) input. Then when the (+) AC output sinewave goes negative a direct short-circuit current will flow in D2 until it blows (which won't take long).

 

[cranker]

thnkz Reloadron ,HTA and crutschow !!!
well Basically I am Making A high frequency INverter , So i Am using 440V ,50Amp Diodes to Rectify It to DC ....
I am Not Using Any transformer i.e using main
than this DC is Applied to Half Bridge Mosfets ....
my ques is that .. Where Should i Place Dc Ground ??? in AC Ground ????
here is the Diagram ....
can u Tell me This is right or not ???

 

[crutschow]

The AC ground is determined by the power line. You can connect the safety AC ground (3rd prong) to the equipment chassis if desired. Do not connect the AC neutral to anything but the diodes (the GND connection you show).

The DC common of the rectifier output should not be connected to anything but circuit common for the MOSFET driver circuits. It must remain isolated from the mains ground. If the MOSFETs are driving a transformer with isolated secondaries, then the secondary common can go to the safety ground if desired, but is not required.

 

[cranker]

means my preceding diagram is right ???
and can i Connect he Common of Triggering circiut to DC ground ???
Can u crutschow Plz draw a Correct Diagram By seeing the Preceding diagram

 

[Nigel Goodwin]

As long as the DC 'ground' isn't ground, or chassis, or anything like that - the entire circuit is live to the mains and must be treated accordingly.

 

[cranker]

Still Confused !!!
Can Any one Plz Give a Diagram Of half brigde high freq Inverter
with 220V Ac .....Rectified to Dc And than Connected to MOSFETS ????

 

[Nigel Goodwin]

What exactly are you trying to do? (and why?).

 

[cranker]

I am trying to Make A high Freq inverter For Induction Heating

 

[crutschow]

means my preceding diagram is right ???
and can i Connect he Common of Triggering circiut to DC ground ???

Depends upon where that ground connection you show is attached. If it's not connected to anything else you are ok.

Yes you can connect the common of the trigger circuit to DC ground. But that "ground" is live due to the connection to the mains power so it is dangerous to touch. We emphasize that point since you seem to have only a hazy understanding of common and grounds.

 

[ADWSystems]

You had it correct in the first drawing. DC ground is right where you pointed. In the AC world, "ground" is a safety aspect not a current carrying conductor. The 'ground' or third prong of the plug is connected to the chassis as crutschow mentioned. AC has HOT and NEUTRAL, and for the purposes in this circuit, doesn't matter which is which.

In your last drawing, GND is in the wrong place. You had it right in drawing #1 and then changed it to be wrong in drawing #2.

 

[cranker]

I am Trying to Make A high freq inverter for Induction heating

 

[cranker]

Now this What I understand ......
Plz Tell me Is it right ??????

 

[ADWSystems]

The ground connection in the upper left on the AC line does not belong there. It will cause a short circuit and blow up the diode.

I believe there should be a connection to ground at the junction of D4 and C1. Can someone else verify/confirm?

 

[cranker]

if i Remove the ground connection in the upper left on the AC line than It will be All Right??

 

[cranker]

This Circiut Is not working

 

[ADWSystems]

Which circuit? You've shown use three. What changes have you made? Which section is not working?

 

[ronsimpson]

On post 24:
V1 is the power line. Remove the GND. That is ground for the 'power line' and not for the rest of the parts.
Add GND at Q2-s. You have U12 and U1 connected to GND and Q2-s not connected to GND. If U1 drives Q2 then Q2-S must connect to U1!.

I usually do not have a power line. I would start off by removing V1, D1-4. and add a DC supply form Q2-d to Q1-s. In your case the power line has confused things.