Lenze IMSS500+ Simple Servo 500 600 i1000 - Manual (Page 55)

SimpleServo 500/600/i1000 User Manual Rev 3.4
7.5 Compensation
7.5.1 Velocity Loop filter
Note
These parameters have an effect on velocity regulator behavior when the SSi is in V+P
mode. It has no effect in PIVFF mode.
• P-gain (Proportional)
Proportional gain adjusts the system's overall response to velocity error. Velocity error is the
difference between the commanded velocity of a motor shaft and the actual shaft velocity. By
adjusting the proportional gain, the bandwidth of the drive is more closely matched to the bandwidth of
the control signal, ensuring more precise response of the servo loop to the input signal.
• I-gain (Integral).
The output of the I-term portion of the integral gain compensator is proportional to accumulative error
over cycle time, with I-term controlling how fast the error accumulates. Integral gain also increases
overall loop gain at the lower frequencies, minimizing total error. Thus, its greatest effect is on a
system running at low speed, or in a steady state without rapid or frequent changes in velocity.
7.5.2 Position Loop filter
• P-gain (Proportional)
Proportional gain adjusts the system's overall response to position error. Position error is the
difference between the commanded position of the motor shaft and the actual shaft position. By
adjusting the proportional gain, the bandwidth of the drive is more closely matched to the bandwidth of
the control signal, ensuring more precise response of the servo loop to the input signal.
• D-gain (Differential)
The output of the I-term portion of the integral gain compensator is proportional to accumulative error
over cycle time, with I-term controlling how fast the error accumulates. Integral gain also increases
overall loop gain at the lower frequencies, minimizing total error. Thus, its greatest effect is on a
system running at low speed, or in a steady state without rapid or frequent changes in position.
• I-gain (Integral)
The output of the D-term portion of the filter proportional to difference between current position error
and position error measured in previous servo cycle. D-term decreases bandwidth and increases
overall system stability. It responsible for removing oscillation caused by load inertia and acts similar to
shock-absorber in the car.
• Vff (Velocity Feed Forward)
The output of the Vff-term portion of the filter proportional to demanded motor speed when drive shaft
travels from position to position. Vff-term is an open loop term. It responsible for removing velocity
error while positioning, thus increasing system response and precision.
• IL – integral gain limit in % of torque
The output of the I-term portion of the integral gain compensator could be limited to some level set by
IL limiter. In other words, influence of I-term on motor shaft torque could be controlled by IL limiter.
This helps to decrease overshoot caused by I –gain especially when position error is integrated over a
long time period.
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