I'm looking for an alternative to a master/follower control like Dart's ASP10. The ASP10 (in follower mode) is a simple PI controller: it counts pulses and adjusts the slave speed to match the ratio set by the operator. We currently are using two 1/2hp dc motors controlled by Dart 125DV-C-K drives (fixed accel ramp at 6 sec. =/ ).
One problem we're having is during starting/stopping. I have both drives powered through a small contactor, so they both are energized at the same time. When the master starts, there is a delay before the follower starts running. The delay is longest on initial powerup. Since the ASP10 is counting pulses and the follower is already behind, it starts running very fast to catch up, overshoots, slows down, and back up as the ASP compensates. When the drives are stopped, the master tends to coast a little longer than the slave. I have adjusted the PI settings to try and get the best performance, but I would like to find something better.
I think part of the problem is the fixed accel on the DC drives. At the very least I'd like to try fitting a VFD and 3 phase gearmotor on the follower for better control options/faster response. I think a servo setup for electronic gearing or camming would also work, but that seems a rather expensive fix. Dart also has an ASP20 that seems to have better control options but I would need two of them. Is there another option for a simple electronic gearing setup?
Ideally (in my mind, at least) I would like to get rid of the Dart controls, use a VFD with an encoder input (or two) to control the follower, and have a speed pot or other control to adjust the ratio. Neither the master speed nor the ratio are changed very often, but sometimes it is necessary.
Thanks for any suggestions
One problem we're having is during starting/stopping. I have both drives powered through a small contactor, so they both are energized at the same time. When the master starts, there is a delay before the follower starts running. The delay is longest on initial powerup. Since the ASP10 is counting pulses and the follower is already behind, it starts running very fast to catch up, overshoots, slows down, and back up as the ASP compensates. When the drives are stopped, the master tends to coast a little longer than the slave. I have adjusted the PI settings to try and get the best performance, but I would like to find something better.
I think part of the problem is the fixed accel on the DC drives. At the very least I'd like to try fitting a VFD and 3 phase gearmotor on the follower for better control options/faster response. I think a servo setup for electronic gearing or camming would also work, but that seems a rather expensive fix. Dart also has an ASP20 that seems to have better control options but I would need two of them. Is there another option for a simple electronic gearing setup?
Ideally (in my mind, at least) I would like to get rid of the Dart controls, use a VFD with an encoder input (or two) to control the follower, and have a speed pot or other control to adjust the ratio. Neither the master speed nor the ratio are changed very often, but sometimes it is necessary.
Thanks for any suggestions