Mesa 7i33 8i20 AC Servo configuration

buster142 wrote:

Have anyone a sample hal configuration for a mesa 8i20 with encoder/resolver feedback?

I am using 8i20 + 5i23 + 7i49

I can give you my config if you want?

However, it is slightly complicated by also having a pair of 7i39 bldc drives and running those in different ways in different configs.

buster142 wrote:

Thanks!
maybe little bit PID tuning but everything is working fine now

You might want to fiddle with the bldc.N.encoder-offset if you are using resolvers. My motors seem to need -950000 in that parameter to give the same current/velocity relationship

If you are using the pid-fb-deriv pin, and have it connected to the resolver-velocity pin then be aware that you may need to set the resolver.N.velocity-scale negative to make the Dgain term work properly.
(It was only today that I realised why I had to use a negative Dgain, now I have negated the scale and Dgain is positive again)

This is the machine working (hot off the camera)

chime wrote:

buying a new set of servo + driver or ultilizar these old servomotors with the 8I20 + 150v transformer for these servos?

I would decide by price. If you can find a matching set of 1kW servo motors and drives then that is probably a good and reliable solution.
The 8i20 is only cheap in the context of servo drives, it still costs quite a lot of money.

that would make me missing transformer for 3 motors?

You might not even need a transformer. I am running on rectified mains (300VDC) with no transformer.
Things are a little safer with a transformer.

A good solution in a 240V country and require 150VDC would be to rectify the output of a site isolation transformer.
www.ebay.co.uk/itm/3-3KVA-SITE-TRANSFORM...ND-NEW-/390646842449
Or similar, you would need a good-sized rectifier bridge and some very large low-ESR capacitors too.

Be aware that the combination of large capacitors and high voltage is very dangerous. I made a circuit to discharge the capacitors.

However, if I was doing the same thing again I would use the fact that the 8i20 has voltage feedback to HAL to control the power supply.
I would make it impossible to turn on the machine and power supply if the voltage is >10V. I would also initially power the PSU through a ballast resistor, until the 8i20 said that the voltage was > 100V. Then I would switch out the ballast resistor and enable the machine. I would do all this in HAL.

You need big, high-current capacitors, for example:
www.ebay.co.uk/itm/EVOX-RIFA-PEH200-CAPA...&hash=item5640b68b16

Are you sure that your machine does not still have a Power supply?