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Subject: Re: ac servo vs. ac inverter
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Date: 11/11/02 at 8:01 PM
Posted by: Barry Penter
In Reply to: Re: ac servo vs. ac inverter posted by vikas Narkar on 11/10/02 at 5:09 AM:
Again, the use of Closed Loop Vector Control will provide the dynamics to move to any position at very low speeds. In the case of the PDL Elite series for example, the ability is there to provide up to 250% of full load torque at zero speed - hence the ability to control the load at zero speed or above. But the key is really to have a controller which will measure the material being processed and control the VSD at the low speeds by analogue control. We use a specially built imbedded PC card which is equipped with a LM628 control chip. However as these are becoming as rare as hens teeth, we have started to use a proprietory card from Baldor to do the same job and still achieving +/- 1/8th mm accuracy whilst running material through the machines at rates of up to 20 meters + per minute.
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