newbie AC Servo question

[GalaticDan]

Hi all,

I've seen Gecko drives for DC Servos and many other peoples drive hardware. I've just started to look at AC drives and hit many bumps with ebay.

1). Most of the drives on EBay I can't seem to find info. on, even at the mfg. homepage?

2). Whats the difference between an AC Servo Drive Amplifier and AC Servo Drive Controller??

3). All I want is step/dir. control and most of these things seem like weighty beasts with simple push button controls but no i/p for step/dir.?

4). Can I mix and match motor with drive/amp? (So long as I match voltage and current requirements...)

5). Any out standing AC drive control products which I should be looking out 4?

Many thanks,

Ping

[Al_The_Man]

Originally Posted by GalaticDan Hi all, 1). Most of the drives on EBay I can't seem to find info. on, even at the mfg. homepage? 2). Whats the difference between an AC Servo Drive Amplifier and AC Servo Drive Controller?? 3). All I want is step/dir. control and most of these things seem like weighty beasts with simple push button controls but no i/p for step/dir.? 4). Can I mix and match motor with drive/amp? (So long as I match voltage and current requirements...) 5). Any out standing AC drive control products which I should be looking out 4?

1/ you might be better to research Manuf. that offer non-dedicated systems, i.e. various makes of motors can be used with their drives. For eg A-M-C and Copley Controls and Aerotech.
2/ AC Servo Drive & Amplifier usually indicate the same thing
3/ See 1/
There are many types of AC servo drives, if you want step & direction I believe you want the PWM type, these work with digital controllers and use a TTL input for PWM & step and direction.
There are usually many of the above makes come up on eBay regularly.
Al

[ESjaavik]

4. Not necessarily. Some drives can be configured only for a limited range of motors from the same manufacturer. Others can be configured to any motor as long as you have enough data on the motors, and they match.

Only bid on an AC BLDC motor and controller after you have found the user manual, read it, understood it, and have determined they are suitable for you.

Some drives are special purpose and not suitable for what you need. In some cases the same drive comes in different flavours (block controller, electronic gear, electronic cam, speed controller, ....) It's a jungle, be sure you have a machete and know how to use it.

[unterhaus]

Originally Posted by ESjaavik Only bid on an AC BLDC motor and controller after you have found the user manual, read it, understood it, and have determined they are suitable for you.

I have quite a collection of drives in the basement because I didn't follow ESjaavik's rule. Now I don't buy unless I know I can use a drive/motor because I have more than a lifetime of projects and only about half a lifetime left.

It's a big subject and hard to give general answers.
A majority of used drives will take an analog control signal.
Step and direction is not as common.

Here is something I posted on cad_cam_edm_dro recently: This was about
some motors that had halls and encoders, if you find matching
motors and drives, that's great.

Originally Posted by Unterhausen Brushless servos are very similar to a three phase induction motor and require a brushless drive. The motors you specified can be driven by most drives that will take either a hall input or hall/encoder inputs. The difference will be how much torque ripple you get. You'll note these take a fairly high voltage. Going with lower voltage will lower the top speed, probably not a big concern. Unfortunately, it takes some research to get the correct drive. You particularly have to pay attention to the resolution of the encoder. Some drives will only use one encoder resolution. Tons of companies make drives that will work, but the prices are high new, think $500 per axis and up. There are lots of drives that only use resolvers, you don't want those. Rutex may be your best bet, but I have no experience with their drives. www.rutex.com Ebay perspective: API makes nice drives, but they charge $500 for the setup software. Pacific Scientific also sells rebranded API and their own drives which might work. AMC makes flexible drives, but it takes some engineering to use them. They tend to be lower voltage. A lot of Compumotor drives only work with one specific type of motor. They bought MTS's servo systems division recently. MTS makes some drives that would work. Electrocraft has some nice drives, also sold by AB and others. Yaskawa might work, haven't looked into it. Some of their motors have absolute encoders, but it looks like the drive can handle incremental encoders. I recently looked into World Servo, they may be the best choice if you have to buy retail. Texas Instruments, Microchip, Freescale Semiconductor, and Analog devices all sell DSP/Microcontrollers that are specifically intended to drive brushless servo motors. Freescale has some nice application notes. As I said, there are tons of companies in this business. I particularly recommend that you obtain the documentation before you buy and make sure it will work with the motors you have and your desired control method. Otherwise you'll end up drowning in drives.