On 3/1/24 08:48, lloyd wilson wrote:
I'm using a Mitsubishi E500 VFD for spindle drive on the VMC I'm
retrofitting & can't get variable speed to cooperate. The mitsub_vfd
program operates properly (I think)- run/stop behaves as expected, speed
commands are generated and accepted by the VFD, but the motor speed
stays the same. I hacked in a couple of debugging statements to show the
dialogs (running in halcmd):
setp sp.motor-cmd 50
halcmd: 01ED11388EF SENT: 0x5 0x30 0x31 0x45 0x44 0x31 0x31 0x33 0x38
0x38 0x45 0x46
7!DEBUG: ,0,1, 0x6 0x30 0x31
show pins
........
4 float IN 50 sp.motor-cmd
.......
then
setp sp.motor-cmd 80
halcmd: 01ED11F40F6 SENT: 0x5 0x30 0x31 0x45 0x44 0x31 0x31 0x46 0x34
0x30 0x46 0x36
7!DEBUG: ,0,1, 0x6 0x30 0x31
show pins
........
4 float IN 80 sp.motor-cmd
.......
the messages are properly formatted per the Mitsub manual & replies show
no errors
--but the test motor keeps running at the same speed.
Anyone have a clue where to look for the solution?
Generally that speed command has to be converted in a pwmgen hal module,
so the signal sent to the vfd is an on/off rapid switch that the vfd
then averages to recover the speed.
See man 9 pwmgen.
Generally again a high speed resolution obtained that way may result in
a slow enough pwm rate that you can hear the pulsing, in which case the
pwmgen module s/b moved to a faster thread than the servo-thread.
However I've not had to do that with either vfd I am using.
Most vfd's are configured for very slow start/stops but can be tuned for
pretty fast response. If you need that, like for quick reversals for
rigid tapping, look at the motors label for FLA means full load Amps,
find the vfd low speed boost setting and make them match.
VFD's are 4 quadrant controls, and that setting insures the motor won't
be overloaded enough to hurt the motor when the vfd has to stop it and
reverse it. I have a 1hp motor and a nearly 40 lb 8" 4 jaw chuck on the
11" Sheldon. At 100 revs fwd I can switch it to reverse, it overshoots
.25 turns, and reverses that 40 lb chuck in 350 to 400 milliseconds. A
side benny is that the shop lights do not blink since the vfd is a 4
quadrant controller, it recovers the energy from the spinning motor
while stopping it, then uses that stored energy from its overcharged
filter caps to re-accel the motor in the other direction. Actual power
from the powerline is drops to zip until it up to around 90% speed in
the other direction. No blinking lights. The caps in the vfd are
catching it from overvoltage but its very short duration, and my theory
(I am a CET) is that its good for the caps, keeping them formed to peak
voltage which makes them last longer. Normally on the back page of the
booklet you will find a recommendation to replace those caps at 5 year
intervals, but they are now 9 years old w/no signs of failure yet.
Take care, stay warm and well.
as always, thanks
-ldw
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
Cheers, Gene Heskett, CET.
--
"There are four boxes to be used in defense of liberty:
soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author, 1940)
If we desire respect for the law, we must first make the law respectable.
- Louis D. Brandeis
_______________________________________________
Emc-users mailing list
Emc-users@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/emc-users
