AC servo system main parameters and setting methods - Database & Sql Blog Articles

Filter 18.432M

Most AC servo system position loops use a proportional regulator, because the integral adjustment can reduce the static difference of the system, but it will produce position overshoot. In systems that require high follow-up performance, the position feed forward gain parameter can be increased. The speed loop and current loop use a proportional integral regulator. The main parameters and meanings of the AC servo that affect the performance of CNC machine tools are as follows:
Speed ​​proportional gain parameter

The main purpose is to set the proportional gain of the speed loop regulator. The higher the gain, the greater the stiffness. The parameter value is determined according to the specific servo drive system model and load condition. Under normal circumstances, the larger the load inertia, the larger the set value.

Speed ​​integral frequency parameter (speed integral frequency is the reciprocal of speed integral time)

Mainly setting

The integral frequency of the speed loop regulator, the larger the integral frequency, the greater the stiffness. The parameter values ​​are determined according to the specific servo drive system model and load conditions. Under normal circumstances, the larger the load inertia, the smaller the set value.

Speed ​​detection low-pass filter parameters, mainly set the speed detection low-pass filter characteristics, the smaller the value, the lower the cutoff frequency, the smaller the noise generated by the motor, if the load inertia is large, the set value can be appropriately reduced. The value is too small, causing the response to slow down and may cause oscillation.

The position proportional gain parameter is mainly used to set the proportional gain of the position loop regulator. The larger the setting value is, the higher the gain is, the greater the stiffness is. Under the same frequency command pulse condition, the position lag is smaller, but the value is too large may cause Oscillate or overshoot.

The current integration frequency parameter is mainly to set the integral frequency of the current loop regulator. The larger the integration frequency is, the faster the integration speed is, the smaller the current tracking error is, but the integration time is too large, and noise or oscillation will occur. This parameter is only related to the servo. The driver is related to the motor and has nothing to do with the load. Under normal circumstances, the larger the electromagnetic time constant of the motor, the smaller the integral frequency, and the parameter is set as large as possible under the condition that the system does not oscillate.

The current proportional gain parameter is mainly used to set the proportional gain of the current loop regulator. The higher the gain, the smaller the current tracking error, but the gain is too high, which will generate noise or oscillation. This parameter is only related to the servo driver and the motor, and the load. Irrelevant, this parameter is set as large as possible without the system oscillating.

Current or torque command low-pass filter cutoff frequency parameter, which is mainly used to set the current or torque command low-pass filter cut-off frequency, used to limit the current or torque command frequency band, to avoid current or torque shock and oscillation, Smooth current and torque response.

Adjusting and changing the AC servo parameters, the characteristics of the servo system are changed. The function of the proportional link parameters proportionally reflects the deviation signal of the control system. When the deviation occurs, the controller immediately produces a control function to reduce the deviation; the integral link function is mainly used. In order to eliminate the static difference and improve the system's indifference; the role of the filter mainly limits the frequency band of the feedback command, avoids external interference shocks and oscillations, and the control system responds smoothly.

In the CNC machine system, the high speed and current gain of the AC servo can bring high servo system response and stiffness, so the machining shape error of the machine tool can be reduced and the positioning speed can be improved. Therefore, as a general adjustment rule, the speed current gain and the integral time constant are adjusted as high as possible, so as to reduce the static difference of the system and increase the rigidity of the system.