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4 Quadrant Operation


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#1 ram14375

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Posted 15 September 2007 - 06:17 AM

dear sirs
kindly brief what is 4 and 2 quadrant operation in drives. when to select a 4 quadrant drive
ram

#2 jraef

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Posted 15 September 2007 - 05:10 PM

Here are the 4 "quadrants" of motor operation:

Motoring forward, Motoring reverse, Braking from forward, Braking from reverse.

2 Quadrant means Motoring functions only, i.e. forward and reverse, no braking.

"He's not dead, he's just pinin' for the fjords!"

#3 marke

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Posted 15 September 2007 - 09:07 PM

I have seen drives advertised as 2 quadrant non reversing.
Not sure if that means that they can do forward motor and forward brake, or it is just marketing license!!

Best regards,

#4 jraef

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Posted 16 September 2007 - 01:17 AM

Actually, methinks I misspoke. You are apparently right Mark.

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It appears as though Quadrant 2 is considered Forward Regen (braking), and you don't get Reversing until Quadrant 3, which, if your drive already had Regen capability in Q2, would mean you jump from 2Q to 4Q.

But then, if you have a drive that can reverse, but not regenerate in either direction, would it be a 1/3Q drive?

I knew all this once, but I must have killed off those brain cells.

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#5 marke

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Posted 16 September 2007 - 01:42 AM

Well I'm not sure that either is right or wrong.
Yes, the four quadrants are correct, and a two quadrant drive could conceivably be either motoring forward and motoring reverse, or motoring forwards and braking reverse.

The terminology has come from DC drives where 1 quadrant drives were common. Motoring forwards only. The reverse function was relatively easily added (reverse the polarity of the armature or field) and we had a two quadrant drive. - motor forwards and motor reverse. The next two quadrants were more difficult to add, and so the regen option gave us the four quadrant drive.

In the case of the AC drive, they are pretty well all forward motoring and reverse motoring as standard so could be considered as two quadrant drives (operating in two quadrants).
When it comes to the braking, there are two options: regen resistor and active front end. These could both be termed as four quadrant drives, but to my way of thinking, the active front end where the energy is returned to the supply is more of a four quadrant drive than the regen resistance drive. The active front end is able to provide full power regeneration continuously, whereas, typically, the brake resistor method is only able to provide in the order of 10% continuous depending on the resistance and brake chopper used.

In the case of AC drives, I can see no reason why you would make a non reversing drive, it does not cost more to make it reverse, so 2 quadrant non reversing seems to be a nonsense for an AC drive. Adding the braking in AC and in DC is quite expensive, particularly if you consider the "return the energy to the supply" option.

Best regards,




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