Servo drive / Servo Amplifier

[Ken_Shea]

What is the non-technical difference between a Servo drive and a Servo amp ?

Thanks
Ken

[Halfnutz]

There is no difference, as far as I know. At one point there may have been, or perhaps there is supposed to be some diference, but the terms are used interchangeably now even within a single manufacturer's product range. I am not the guru, I could certrainly be wrong, but I cant find any definitive difference between the two.

[Ken_Shea]

That was beginning to be my conclusion as well, there seems to be a lot of this double talk that injects so much confusion when trying to understand something.

Maybe we have a wrong understanding of this.


Thanks for the reply.

Ken

[imserv]

Servo amps usually are driven by analog voltages 0-10v, 0-5v, +/-10v (probably the most common), pwm, etc. They do not usually have any closed loop electronics.

Servo drives often have more complex control methods, such as step and direction or serial peripheral interface (SIP), and will sometimes include an encoder and or Hall effect sensor interface.

Examples of inexpensive servo drives:

DeskCNC SV-500 http://www.imsrv.com/deskcnc
Rutex http://www.rutex.com
CNC Teknix http://www.cncteknix.com
Geckodrive http://www.geckodrive.com

Fred Smith - IMService
http://www.cadcamcadcam.com/hobby

[NC Cams]

Sounds like the servo amp/drive terms have encountered the same fate as engines/motors - their names are used interchangeably and incorrectly so.

[Al_The_Man]

In my experience, there has never been a clear definition either way, hence the practice of using the terms interchangeably.
In electronics generally there has always been a tendency to use Driver and Amplifier as one-and-the-same, as one is often also the other.
Al.

[daedalus]

i always assumed that drives included feedback algorithms, such as position control devices, whilst amplifiers were open loop torque control. (at least thats the terminology we use at work)

[mcpltd]

I have allways thought they were the same, i even hear them called drive amplifier.

[NC Cams]

The "drive" is typically the high power switching section.

In a DC drive, this is purely an "H" bridge that provides a combination of CW and CCW and braking capabilities. I've not worked with AC so i can't speak for them but they do the same thing only a different way - usually via commutation changes.

The "amplifier" part comes in becasue of the use of control voltage as opposed to high power switching voltage.

The control side is usually low voltage 5, 12 or 24 volts. The power side is anywhere from 12 to 240 depending on if it is DC or AC or whatever. The trick comes in how you "amplify" the ability of 5, 12 or 24 volts to switch much higher power and/or current.

The drive becomes more than a simple switching controller when you start to add current monitoring, over and under voltage monitoring and other checks for fault conditions. These can/will not only shut down the drive pass elements but they can also "tell" the controller that a shut down has occurred to stop the machine from continuing it's motion when the amp can'/won't be able to drive the motor.

Yes, they are interchangeable terms. Sort of like motor for engine and vice versa. Essentially, however, they both do the exact same thing.

[Al_The_Man]

I think 'Drive' and 'Amplifier' has become a question of semanitics, servo drives usually amplify, and amplifiers generally have drivers.
I guess in the case of an SCR 'Drive' it could be termed just a drive, because does it actually amplify or just switch?
Al.