Need help :: FULLY-CONTROLLED SINGLE-PHASE SCR BRIDGE RECTIFIER: RL LOAD

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Then this is not a at all rectifier............
 

Then this is not a at all rectifier...
People actually use to name it controlled rectifier.

But your optocouplers don't have 400V or so voltage rating, isn't it? Trigger transformer is the classical solution, opto triacs can be used if dV/dt is low enough to avoid self-triggering.
 

People actually use to name it controlled rectifier.

But your optocouplers don't have 400V or so voltage rating, isn't it? Trigger transformer is the classical solution, opto triacs can be used if dV/dt is low enough to avoid self-triggering.


Is that the image i mentioned is controlled rectifier ? ? ?

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Small change could help you....... Invert the logic in the output
 

In the circuit you shown, the Cathode is connected to ground, so you can get the zero referencing...But look at the controlled bridge rectifier, the cathode of SCR is not connected to ground, It is connected to the power + Bus DC Voltage. So your circuit is not applicable to this case. Plz think it again. Thanks for the reply
 

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Forget the Ground it does nothing here... The relevent ground in your circuit is SCR cathode It will work with the negative voltage came from another limp Diode.... try in simulation...
 

So what you say...The circuit i connected the SCR with optocoupler will work...???
Cathode is not in the negative voltage it is in +Bus of DC Voltage.
 

Clearly look at it for U1 the D2 will ON and the positive rail will be negative before U1 turn ON and for U1...
 

The circuit i connected the SCR with optocoupler will work...???
It can't work, for the simple reason that no transistor opto-coupler stands 300 or 400 V. I already mentioned this in post #42, don't know if you just ignored the comment or don't understand the problem. :-(

P.S.: I don't discuss the meaningless case shown in your schematic, where the opto coupler LEDs are always powered . If we want the thyristors permanently turned on, we place diodes instead.
 
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I clipped some part in #39.. that uses separate 5V source for firing SCRs(from micro controller)..
optocoupler never works in main voltage...

And if you want without any sources means convert your outputs into pulse train(by and logic with some frequency) and then give it through a pulse transformer...

**broken link removed**

 

In the second diagram , Another end of secondary side of Pulse transformer is connect to AC line..It is dangerous, that High voltage AC line is directly connected to Return path of pulse transformer. It may be OK for some theoretical explanation But It will not work in practical application.

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No..Its not meaningless...I connected +5v just for showing , will be coming from microcontroller...It is not permanently giving with +5v it is coming from digital input...
 



That is just an example circuit... in your circuit it will be on the +ve rail, and also i never seen a problem when one end of pulse transformer connected in a phase...

And the important thing, you have quickly remove MCs 5V for firing, because it will link with rectified +ve rail and can damage your MC in any moment... use a separate source or go for pulse transformer....
 

I wonder if I missed something in the schematic? The secondary side is connected to AC line, that's no problem. The primary side is isolated. It's not just a theoretical explanation, it's a fully working circuit.
 

You can do it with a single SCR connect the load in series with a diode bridge and connect an SCR between positive and negative outputs of the bridge Very easy
 

You are saying pulse transformer when connected to phase is not a problem....Its strange , 230VAC !!!...But let me check in hardware....
Big problem in that circuit, It may be fire the SCR but after turning on the Secondary of the pulse transformer voltage will induce a voltage on the primary which ll destroy the circuit connected to primary....

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You can do it with a single SCR connect the load in series with a diode bridge and connect an SCR between positive and negative outputs of the bridge Very easy



It also have the same problem, Floating Cathode!!!!
 
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