Magtrol DSP6000 User Manual - page 15
9
Magtrol Model DSP6000 Dynamometer Controller
Chapter 2 - About the PID Loop
The larger the I value the faster the DSP6000 will move
to the target number, but an I value too large will cause
instability (oscillation). Once the optimum values are
found, these steps should be repeated at different
percentages of speed to ensure that they are the best
combination for the entire speed range.
NOTE:
The PID values for a speed
stabilized test and a ramp test
will vary. Therefore, PID
adjustments may be needed when
changing from a stabilized test to
ramp testing with the same
motor.
The D value has little or no effect on this type of testing,
therefore the D value can remain at zero.
3. Turn the brake to the ON position and observe how
the actual speed moves toward the target speed.
4. If the speed moves slowly or not at all, increase the
P until the target speed is achieved.
5. Turn the brake OFF.
6. Turn the brake ON and note how fast the free-run
speed changes to the target speed.
7. If the speed conversion does not happen quickly,
increase the I value.
8. Repeat steps 4-7 until the motor moves from the
free-run to the target speed as quickly as possible
without excessive overshoot.
Example:
Motor type:
AC
Free-Run speed:
1750
1. Set maximum speed to 1800
2. Set P = 5 I =5 D = 0
3. Set target speed to 1600
4. Turn brake ON—no response
5. Move P value to 10—still slow, not reaching 1600
Note:
Increasing the P more will not
increase the operating
characteristics without first
increasing the I value.
6. Turn brake OFF
7. Move I value to 10
8. Turn brake ON—Reaching 1600 very slowly
9. With the brake OFF, adjust the P to 15
10. Turn the brake ON—never reaching 1600
11. Turn the brake OFF. Decrease the P to 10 and
increase the I to 15
12. Turn the brake ON—reaches 1600 Faster
13. Turn the brake OFF. Increase I to 20
14. Turn the brake ON—reaches 1600 Faster
15. Turn the brake OFF. Increase I to 25
16. Turn the brake ON—reaches 1600 Faster
17. Turn the brake OFF. Repeat