[mike_Kilroy]

could be an instability in the sensorless loop of course, also could be a resonance in the motor itself; even in v/hz motor on some sophisticated spindle motors we have seen this shaking around at 1 or two slower speeds like this.

Closing the loop with a & B channels of encoder would obviously change things so if you want to try, go for it of course. No clue if it would help.

closing loop in kflop won't do anything for you of course since the issue is in the motor/drive.

But, although I have never seen your issue with a hitachi before, for the few times I have had issues with sensorless control, I have changed the H sensorless or loop parameters and tweaked my issues away. Remember, the self tuning thing is a bestest guess... It is up to you to tweak the parameters more if you are not satisfied with what you got.

There are only like 25 possible H variables, and IIRC, you can changae them on the fly, so easy to try going up and down a bit on each one to see if you can find the one causing this...

Most likely IMO are H005, 6, 20-24, 30-34 (not sure if they are used after autotuning), 50-51. Manual talks about tweaking these too IIRC.

Lastly, you can always just not program that speed and accel/decel thru it instead.

[engnerdan]

could be an instability in the sensorless loop of course, also could be a resonance in the motor itself; even in v/hz motor on some sophisticated spindle motors we have seen this shaking around at 1 or two slower speeds like this.

Closing the loop with a & B channels of encoder would obviously change things so if you want to try, go for it of course. No clue if it would help.

closing loop in kflop won't do anything for you of course since the issue is in the motor/drive.

But, although I have never seen your issue with a hitachi before, for the few times I have had issues with sensorless control, I have changed the H sensorless or loop parameters and tweaked my issues away. Remember, the self tuning thing is a bestest guess... It is up to you to tweak the parameters more if you are not satisfied with what you got.

There are only like 25 possible H variables, and IIRC, you can changae them on the fly, so easy to try going up and down a bit on each one to see if you can find the one causing this...

Most likely IMO are H005, 6, 20-24, 30-34 (not sure if they are used after autotuning), 50-51. Manual talks about tweaking these too IIRC.

Lastly, you can always just not program that speed and accel/decel thru it instead.

Mike,

When I mentioned closing the loop in my motion controller it was not for solving the instability issue, it was just to keep stable RPM's at all other times.

I will have to come back to the instability and closed loop in the future, I have been swamped with parts to make on the mill and it has been running like an open sore (a good sore in this case). I changed a parameter I mentioned before related to the braking to try and prevent the drive from tripping out. I also took your advice and upped the voltage to 230 volts, plus I cranked up the current to the max for this drive (25 amps I think) and rated motor size to 5.5 kw to test. I will leave the amperage at 25 because that is the closest I can get to the rated amperage of 26 amps at the 3.7kW overload condition. But I will most likely drop the 5.5kW motor size down to 3.7kW of I can without lowering the peak amperage any.

So all this has resulted in some deep thinking, continuing down this rabbit hole.


Right now I am reading the amperage and voltage output from the VFD into a bar graph on my HMI. But it has occurred to me that I am using the raw amperage, voltage, and calculated kW. So should I be scaling that kW's down to account for efficiency in the motor? Because ultimately if my motor is rated at 2.2/3.7kW output at the shaft that is what I want to watch for in my load meter.

Then I got to more thinking and converted the amp draw in 3 phase to the single phase equivalent. 16*1.73 = 27.68 amps, 26*1.73=44.98 which means I need to check the fuses I used on my initial assembly of my mill. I think I only put 30 amp fuses in and I know I have run up the raw kW draw to over 4kW without blowing any fuses. But as I type this out it makes sense now (as I am typing this out), I should be able to pull about 6.9kW at the VFD output before the fuses go. Does all this make sense to you?


So my next question for you is, would you scale the scale the raw kW output from the VFD if you were displaying it on a HMI? Is so what do you think of my calculations below to determine an approximate efficiency (scaling factor)?

For the numbers below I used the name plate rating of 216 VAC, I could use 220 or 230VAC but that would only lower the efficiency.

Rated kW 100% eff amps Nameplate amps Efficiency ?
2.2 kW 10.2 amps 16 amps 63.75%
3.7kW 17.1 amps 27 amps 63%


-Dan

[mike_Kilroy]

1) Right now I am reading the amperage and voltage output from the VFD into a bar graph on my HMI. But it has occurred to me that I am using the raw amperage, voltage, and calculated kW. So should I be scaling that kW's down to account for efficiency in the motor? Because ultimately if my motor is rated at 2.2/3.7kW output at the shaft that is what I want to watch for in my load meter.

2) Then I got to more thinking and converted the amp draw in 3 phase to the single phase equivalent. 16*1.73 = 27.68 amps, 26*1.73=44.98 which means I need to check the fuses I used on my initial assembly of my mill. I think I only put 30 amp fuses in and I know I have run up the raw kW draw to over 4kW without blowing any fuses. But as I type this out it makes sense now (as I am typing this out), I should be able to pull about 6.9kW at the VFD output before the fuses go. Does all this make sense to you?

3) So my next question for you is, would you scale the scale the raw kW output from the VFD if you were displaying it on a HMI? Is so what do you think of my calculations below to determine an approximate efficiency (scaling factor)?
For the numbers below I used the name plate rating of 216 VAC, I could use 220 or 230VAC but that would only lower the efficiency.
Rated kW 100% eff amps Nameplate amps Efficiency ?
2.2 kW 10.2 amps 16 amps 63.75%
3.7kW 17.1 amps 27 amps 63%

-Dan

Whew! Been too long to recall details...

1) If doing math, I would think y ou would want to do it based on the motor rating
2) ok I guess
3) I do not recall details so no comment. But I would say in general you should not be trying to figure in any efficiency; the motor nameplate gives you the specs that produce the rated output already.