Kinco FD5P AC series servo driver
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Chapter7:Tuning of the servo system control
Speed step curve：Curve that shows rise/fall changes.
The vibration and noise of the motor can be felt by hand touch and listening
Steps required for adjustment of the velocity loop:
Step 1：Adjustment for Kvp
Increasing Kvp can improve the bandwidth of the velocity loop and make the velocity response
ability faster. To calculate the Kvp, please refer the following formula。
Kt Motor torque constant
，unit N.m/Arms*100
J
inertia，unit kg*m^2*10^6
B
B Velocity loop bandwidth unit: Hz
I
max MAX mortor current(6510.03)，unit: DEC
Encoder Resolution of the encoder
Because the -3 of Operation_mode has no acceleration and deceleration and does not participating
the velocity loop control, the -3 mode and automatic flip mode can be used to run the motor when
adjusting the velocity loop parameters. During the reciprocating motion, the responsiveness of the
servo can be monitored by collecting the speed step curve
If the Kvp too low, the bandwidth of the velocity loop and the position loop will not match, which will
lead to oscillation. If the Kvp is too high, it will cause the speed to overshoot and cause the speed
loop to oscillate. In some rigid connection loads (such as ball screw, rack and pinion, etc.) The Kvp
should be as high as possible. By comparing the oscillograms under different Kvp, find the optimal
curve – the actuall speed curve should be tight follows the target command and does not have
velocity oscillations.
Figure 7-4 Speed step curve after Kvp adjustment
Step 2 ：Adjustment for Kvi
Kvi is designed to eliminate static errors. It can strengthen the low frequency gain of the velocity
loop, and a large Kvi can reduce the response ability from low-frequency disturbance, thereby
improving the anti-disturbance capability in low-frequency.
When Kvi is too small, The integral time will be long. The error adjustment will be slow, and it will
take longer time to make the system entering steady state. When the integral gain of the speed
loop is too large, the error will appear and in severe cases, the motor may oscillate. Kvi should be
adjusted to the servo eliminating the error and enter a stable state efficiently.
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