Lenze S94P01G Position Servo - Manual (Page 62)

S94P01G
60
Operation
Step 2: Fine Tuning the Velocity P-Gain
Slowly alter the Velocity P-Gain (increase and decrease) and observe the motor velocity
waveform on the oscilloscope. As the P-Gain increases the gradient of the velocity
during acceleration and deceleration will also increase as will the final steady state
velocity that is achieved. The application of too much P-Gain will eventually result in an
overshoot in the motor velocity, and further increases will result in larger overshooting
to the point that instability (continuous oscillation) occurs.
Increase the velocity P-gain until some overshoot occurs. Some overshoot is generally
ok, and the objective is typically to achieve the shortest possible settle time (steady
state velocity). When the system appears to have reached the shortest possible settle
time, with acceptable overshoot, cease from increasing the P-Gain.
Scope traces will be similar to those shown in Step 1, however the P-gain will now be
given a more precise adjustment in order to obtain the best possible tuning.
Good Fine Tuning of the P-Gain
Small overshoot with excellent settle time and
steady state velocity regulation.
Step 3: Setting the Velocity I-Gain
The purpose of the velocity I-gain is to correct any error that is present between
the commanded velocity and the steady state velocity that could not be rectified by
adjustment of the velocity P-gain. Adjustment of the velocity I-gain can also reduce the
steady state ripple that may occur in the velocity waveform. Lastly, velocity I-gain has a
positive effect on the holding torque produced by the motor.
Slowly increase the “Velocity I-Gain” and check for correction of the steady state error
in the velocity waveform. Continuing to increase the velocity I-gain will eventually result
in increased overshoot and instability in the motor velocity waveform. Stop increasing
the I-Gain when additional overshoot or instability starts to occur.
I-Gain set too LOW
Error exists between Commanded steady
state velocity and Actual steady state velocity