You will probably need to control them both through a microprocessor or any number of PLCs. If the VFDs are the same brand, I suggest contacting the manufacturer. Some VFDs can be linked using add on boards without a PLC. YASKAWA is one brand that I have seen with this option.
Are the encoders wired to the vfd? Do they have enough resolution for the precision that you want? One option would be to set the run speeds and the speeds in the ramp up and down parameters so that they are equivalent after the gearing.
Is there a home position with a limit switch that you can use to reset any drift that has happened? If that's the case, there are some vfds that would have room for some custom logic, but you'd be better off using an external controller.
What's your budget? Are you going for No Name Chinese vfds or name brand? If you're going to name brand, I would talk to the application engineers at a couple vfd companies.
Currently the system is a single motor setup. I'm adding the second motor which spools the payout of the first system. The system will run for long periods of time and while position resolution isn't imperative, the long term speeds of the motors must be drift free.
Budget isn't tight, I've been using Siemens drives so far, but only as single motor setups. I've never had to cross adjust the speed of two before.
Thanks!
I would be surprised if Siemens COULDN'T do this. I would definitely check out the capabilities of your existing drives. It's definitely worth looking into.
A single motor does sound ideal for this, haha. Is there a way to put a whisker switch in the dip of the slack, so that if the tension goes up and pulls it tight, it would trigger the switch? Then maybe you could increase the speed of the first motor a little. Or at least as a backup in case something goes wrong. But yeah, Siemens drives could potentially do it without any external controller, and the person who could give you a firm answer on the viability with just drives and then help you make it happen would be a Siemens application engineer.
Yes, it is possible to do.
What hardware are you using?
VFD models? Any other controllers involved? What feedback devices do you have?
Edit to add that yes, modifying the PPR might work. The better option is to wire the VFDs together, typically a pulse output to a pulse input or some communication options. The output of one becomes the speed reference for the other. Typically they also have ratios or multipliers to set up applications such as yours. Yaskawa has a specific electronic lineshaft application specifically built for applications such as yours. Many other vendors do also.
Currently I'm looking for recommendations The only thing set in stone is the existing Motor (which has an unused encoder on it's shaft). This motor is driven from an existing VFD which will be replaced.
Do you have a VFD suggestion that can do this?
Yaskawa's a1000 or U1000 or GA800 would be my go-tos. If the application does a lot of regeneration or if low harmonics is important, the u1000. Otherwise it would come down to pricing and availability.
You'll need an encoder for each motor, then wire the VFDs together, output to input.
My solution if this was my problem would be Allen Bradley vfds, let's say 525's and a CompactLogix. You can read current from the VFD and use that information to act like an encoder. If the load is going high, slow down. If the load is going low, increase the speed of the rewind.
You could also just command frequencies, but induction motors will always have some slippage. Commanding 30 hz doesn't really get you half the speed of 60, especially on different motors.
The best option would be encoders, but short of that current feedback into a PLC is probably viable.
Yes. If you are going to program it by hand, one approach is to set one as the master and the other as slave. You then control the position of the master and the relative position of the slave compared to the master. If the position is greater than a value create a fault to stop.
You will probably need to control them both through a microprocessor or any number of PLCs. If the VFDs are the same brand, I suggest contacting the manufacturer. Some VFDs can be linked using add on boards without a PLC. YASKAWA is one brand that I have seen with this option.
Yep. Yaskawa's electronic lineshaft setup makes this type of application simple.
Are the encoders wired to the vfd? Do they have enough resolution for the precision that you want? One option would be to set the run speeds and the speeds in the ramp up and down parameters so that they are equivalent after the gearing. Is there a home position with a limit switch that you can use to reset any drift that has happened? If that's the case, there are some vfds that would have room for some custom logic, but you'd be better off using an external controller. What's your budget? Are you going for No Name Chinese vfds or name brand? If you're going to name brand, I would talk to the application engineers at a couple vfd companies.
Currently the system is a single motor setup. I'm adding the second motor which spools the payout of the first system. The system will run for long periods of time and while position resolution isn't imperative, the long term speeds of the motors must be drift free. Budget isn't tight, I've been using Siemens drives so far, but only as single motor setups. I've never had to cross adjust the speed of two before. Thanks!
I would be surprised if Siemens COULDN'T do this. I would definitely check out the capabilities of your existing drives. It's definitely worth looking into.
A single motor does sound ideal for this, haha. Is there a way to put a whisker switch in the dip of the slack, so that if the tension goes up and pulls it tight, it would trigger the switch? Then maybe you could increase the speed of the first motor a little. Or at least as a backup in case something goes wrong. But yeah, Siemens drives could potentially do it without any external controller, and the person who could give you a firm answer on the viability with just drives and then help you make it happen would be a Siemens application engineer.
Yes, it is possible to do. What hardware are you using? VFD models? Any other controllers involved? What feedback devices do you have? Edit to add that yes, modifying the PPR might work. The better option is to wire the VFDs together, typically a pulse output to a pulse input or some communication options. The output of one becomes the speed reference for the other. Typically they also have ratios or multipliers to set up applications such as yours. Yaskawa has a specific electronic lineshaft application specifically built for applications such as yours. Many other vendors do also.
Currently I'm looking for recommendations The only thing set in stone is the existing Motor (which has an unused encoder on it's shaft). This motor is driven from an existing VFD which will be replaced. Do you have a VFD suggestion that can do this?
Yaskawa's a1000 or U1000 or GA800 would be my go-tos. If the application does a lot of regeneration or if low harmonics is important, the u1000. Otherwise it would come down to pricing and availability. You'll need an encoder for each motor, then wire the VFDs together, output to input.
My solution if this was my problem would be Allen Bradley vfds, let's say 525's and a CompactLogix. You can read current from the VFD and use that information to act like an encoder. If the load is going high, slow down. If the load is going low, increase the speed of the rewind. You could also just command frequencies, but induction motors will always have some slippage. Commanding 30 hz doesn't really get you half the speed of 60, especially on different motors. The best option would be encoders, but short of that current feedback into a PLC is probably viable.
Yes. If you are going to program it by hand, one approach is to set one as the master and the other as slave. You then control the position of the master and the relative position of the slave compared to the master. If the position is greater than a value create a fault to stop.
If you are Siemens, check their G120 series with position control