Concept Of Adjustment Of Manual Input Speed Control Gains; Speed Control Gain Adjustment Procedure (Pr. 820, Pr. 821) - Mitsubishi Electric FR-V500 Instruction Manual

Fine adjustment of gains for speed control
2.3.2

Concept of adjustment of manual input speed control gains

1) Speed control P gain 1
Pr. 820 = 60% is equivalent to 120rad/s (speed responce of
the motor alone). (factory setting)
Increasing the proportional gain increases the response level.
However, a too high gain will produce vibration and/or
unusual noise.
2) Speed control integral time
Pr. 821 = 0.333s (factory setting)
Decreasing the integral time shortens the return time taken at
a speed change. However, a too short time will generate an
overshoot.
When there is load inertia, the actual speed gain decreases as given below.
Actual speed gain = speed gain of motor without load ×
Load variation
Speed
2.3.3

Speed control gain adjustment procedure (Pr. 820, Pr. 821)

• Set "0" in Pr. 819 "easy gain tuning". (Easy gain tuning is not performed.)
Refer to the Instruction Manual (basic) for easy gain tuning.
• Refer to the following for manually input gain adjustment.
Manual input gain adjustment
• Pr. 820 "speed control P (proportional) gain 1", Pr. 830 "speed control P (proportional) gain 2"
• Pr. 821 "speed control integral time 1", Pr. 831 "speed control integral time 2"
Make adjustment when any of such phenomena as unusual machine vibration/noise, low response level and
overshoot has occurred.
1) First check the conditions and simultaneously change Pr. 820 "speed control P gain 1" value.
2) If you cannot make proper adjustment, change Pr. 821 "speed control integral time 1" value and repeat step (1).
CAUTION
Pr. 830 "speed control P(proportional) gain 2" and Pr. 831 "speed control integral time 2" are made valid when
the RT terminal is switched on. Make adjustments in the same way as Pr. 820 and Pr. 821.
No. Phenomenon/Condition
1 Large load inertia
Vibration/noise generated
2
from mechanical system
3 Slow response
Decreasing the integral time shortens this return time.
Set the Pr. 820 and Pr. 821 values a little higher.
When a speed rise is slow, increase the value 10% by 10% until just before
Pr. 820
vibration/noise is produced, and set about 0.8 to 0.9 of that value.
If an overshoot occurs, double the value until an overshoot does not occur, and
Pr. 821
set about 0.8 to 0.9 of that value.
Set the Pr. 820 value a little lower and the Pr. 821 value a little higher.
Decrease the value 10% by 10% until just before vibration/noise is not produced,
Pr. 820
and set about 0.8 to 0.9 of that value.
If an overshoot occurs, double the value until an overshoot does not occur, and
Pr. 821
set about 0.8 to 0.9 of that value.
Set the Pr. 820 value a little higher.
When a speed rise is slow, increase the value 5% by 5% until just before
Pr. 820
vibration/noise is produced, and set about 0.8 to 0.9 of that value.
46
Proportional gain
200rad/s
120rad/s
(Factory setting)
J
M
J : Inertia of motor
M
J +J
J : Motor shaft-equivalent load inertia
M L
L
Since increasing the proportional gain increases the
response level, this speed variation decreases.
Adjustment Method
Pr.820
setting
60% 100%