Vel_I_Gain

General

Functional Description

Is used to enter the integral gain of the velocity controller in percent. It defines how pronounced the modification of the reference current is when the actual velocity deviates from the reference velocity. The integral part helps to recognize that deviations of velocity and position controller can be corrected without a static offset. If the disturbance variables, which externally influence the control loop, were constant, a tracking deviation of close to zero could be achieved.

100 % is the theoretical maximum possible dynamic in relation to the entire reduced drive mass moment of inertia (also see the calculation of adjustable values of the parameter J_Load parameter). The internal controller gain, which is parameterized via Vel_I_Gain, is additionally dependent on J_Load and J_Gear for rotary drives, and is additionally dependent on LoadInertial­Linear for linear drives. These parameters must be checked before configuring Vel_I_Gain. The default value is set to 5 % in order to obtain a stable behavior for as many mechanisms as possible.

If the parameter VoltageFeedForwardMode is set to Dynamical behavior of the control loop / 3, the dynamic of the velocity controller is increased. A maximum value of 250 % is possible.

Due to the increase of Vel_I_Gain, the dynamic of the speed control loop can be increased and so the tracking deviation can be reduced. However, a too high value may lead to the control loop becoming unstable. The value for which the stability limit is reached is dependent of the parameter Vel_P_Gain and the mechanics connected to the motor. To achieve a low tracking deviation, optimal conditions must be determined.

NOTE: The parameter value is transferred from the master to the slave via the parameter channel of the Sercos at every access. Typically, this takes about 10 ms. However, times up to 1 s can occur if there is a lot of data transferred on the parameter channel.

NOTE: This parameter can be determined as of firmware version V01.35.x.0 by using the AutoTune automatic controller optimization.

This parameter has no effect for asynchronous motors in open-loop V / f mode (ControlMode = open-loop control / 1).