Digital DC Drive Woes

[pzzamakr1980]

Hello, I'm using a Fenner Contrex/Parker Zenith ZeDrive to run a 2hp DC Motor for my spindle on my X3. Its going pretty well except for it will slow down and speed up when load conditions change. It does this pretty drastically, ie going from 1400 rpm to 800 rpm before the drive will change power output and it will come back up to 1400 rpm. I would like it to either be a little quicker about how it goes back or, best scenario, I don't want the rpm to change so much in the first place. I have messed around with the settings but just cant seem to get it right. Does anybody have any experience with these drives. They are typically used for pumps and metering, and as such must maintain a very constant flow even under load changes, so I know this drive is capable of doing it. Thx for the help.

[Mike Nash]

My first thought was to increase the feed-forward parameter, but in looking in the manual there isn't one in this version, or it's factory set. The fact that Trim Authority is factory set to 100% looks a little ominous.

What are you using for reference and feedback signals? Maybe Contrex/Parker (Fenner, whomever they are this month) still has it incorporated as a fixed value as they mention it once in the Trim Authority parameter details.

Since M47 and M48 have also been deleted (See the M-Drive Manual if interested) I would say it may not have a feed-forward at all, which would be fairly typical of a pump drive control.

First, you need to make sure your parameters in 20-23 and 30-38 are really close so the Reset (Integral) isn't doing most of the work.

Then try adding some Recovery Multiplier (Parameter 29) to see if that helps with the load induced speed droop. Too much will probably cause speed oscillation, especially after a load change so watch for that. You'll also need to set 18 and 19 to non-zero values. Since with the lead lag pulse limit of 0 will negate the Recovery Multiplier.

Finally, if none of that works either call Contrex or find a more suitable spindle drive.

Good luck!

[pzzamakr1980]

Thx Mike, that seemed to help out a good bit. As far as appropriate, it was 50 bucks and compared to the board that drives the stock x3 motor, its a million times better. I can now run a 2hp motor, and can use a 1/2in drill bit at 1500 rpm, while still going up to 6000 rpm, without a belt change. I dont really need to go lower since I dont use any tools that require more power than a 1/2 drill bit. As far as support from the "manufacturer" it has been non-existent. So thank you again for the help.