difference between 2-quadrant and 4-quadrant speed controllers

[medo79]

What is the difference between 2-quadrant speed controller and 4-quadrant in brushless DC motor controller?

 

[itsmoked]

Two quadrant means it will go forward and backwards while providing work - like a motor.


The other two quadrants refer to the motor now being driven by something and the the power being returned to the controller for storage or dissipation - the motor acting as a generator.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[medo79]

Many thanks Keith,
I have another two question:
1- What about 1-Quadrant motor driver?
2- If I want to control the braking mode for the motor as well as the motor mode, what is the suitable motor driver "1-Q, 2-Q or 4-Q"?

 

[itsmoked]

One quadrant would be just a switch hooked up to the motor. Turn it ON it goes in one direction. The switch could be PWM or just an analog voltage that goes from 0V to xV. If you wanted to reverse the motor you'd have to reverse the wiring. (For a DC motor) with an (AC motor) you'd have do whatever else is needed to reverse it.

If you want both directions, motor/braking, you'd need a four quadrant controller. If you just want one direction, theoretically, you'd need only a 2 quadrant but I can't say I've ever seen one that is the 'correct' two qudrants.. Normally I see the two quadrants as being only direction 'forward and reverse' not motor and generate.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[ScottyUK]

1 quadrant = one direction, no regeneration

Braking would require a 2 quadrant drive, but not the two quadrants you get from a reversing type!

Define the quadrants:

1 - forward, motoring
2 - reverse, motoring
3 - reverse, generating
4 - forward, generating

You need a regenerative drive to effect braking, which likely will be a four quadrant drive even if you don't want the reversing feature.


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If we learn from our mistakes I'm getting a great education!

 

[medo79]

@Keith
What do you mean by " Normally I see the two quadrants as being only direction 'forward and reverse' not motor and generate"?

@SottyUK
What do you mean by "Braking would require a 2 quadrant drive, but not the two quadrants you get from a reversing type!"?

I am a little bit confused. Is 2-quadrant drive used to control motor in forward and reverse direction while 4-quadrant used for motor/regenerative drive (motor/generator)?

 

[amptramp]

Read the document found at the link below. The quadrant definitions are on page 12.

http://literature.rockwellautomation.com/idc/groups/literature/documents/td/drives-td000_-en-p.pdf

 

[jraef]

I think the confusion is in the semantics.

There are 4 quadrants:
#1 = Motor CW
#2 = Regen CW
#3 = Motor CCW
#4 = Regen CCW

THEN there are either 1, 2 or 4 quadrant drives.

A drive that is 1Q is #1 only
A drive that is 2Q can be #1 + #3, or it can be #1 + #2. Saying just "2 quadrant" is technically insufficient to differentiate. I have always said "2Q reversing" or "2Q Regen (or Braking)"
A 4Q drive is of course #1, #2, #3 and #4 and so needs no further qualification.



"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[medo79]

Acording to maxon driver, 1-Q driver works in both Q-1 and Q-3. Please, have a look on page 4 in this file:

http://www.maxonmotor.nl/be/nl/downloads/mmc_2006_e.pdf

I have another question regarding to 4-q driver. Could I use 4-Q drive to work as bidirectional amplifier to actuate the motor in Q-1 and Q-3, and recharge a battery in Q-2 and Q-3?

 

[Skogsgurra]

The numbering of the quadrants, or rather the allocation of speed and torque direction, is somewhat arbitrary. It makes a difference if speed is on the horizontal axis or vertical. The numbering is always from #1 (upper right) and CCW.

To add to the confusion, VFDs are sometimes called 4Q drives if they have a braking resistor instead of using proper regeneration. The rationale for this is that all VFDs can drive FW and BW, i.e. Q1 and Q3. With the braking resistor, they can also brake in Q2 and Q4.

The marketing people then say that it can do everything that a genuine 4Q drive can - so it is a 4Q drive.

What they do not tell you is that the braking power is limited by the resistor and - more important - you do not regenerate. So all the braking energy, that you planned to 'sell back' to the grid is lost as heat in the resistor.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[amptramp]

Fundamentally, your basic 1-Q drive has just enough circuitry to control the motor in one direction and without braking (1-Q - Motor CW) . To reverse the direction of the motor (3-Q operation - Motor CCW), a reversal of either the armature or field polarity must occur. In the "old days" when power electronics were still expensive, if you wanted the motor (being controlled by a basic 1-Q drive) direction reversed, you used a screwdriver to reverse either the field or armature wiring. Some drives had relays and switches mounted on the drive to reverse the wiring. If the Maxon driver has circuitry to reverse the direction of motor rotation then technically it should be referred as 2-Q Reversing.