SIEMENS SINAMICS S120 Servo Drive System Application Guide

Motor optimization technology

To achieve optimal control performance, SINAMICS S120 provides comprehensive motor optimization functions, including motor data calculation, static identification, and dynamic identification.

4.1 Automatic optimization

For Siemens standard motors, the "Automatic controller setting" function of SCOUT software can automatically optimize the controller dynamically. Before optimization, it is necessary to ensure that the motor is in a cold state, the brake is released, and the mechanical system is safe. During the optimization process, the system will automatically perform self-tuning of the speed loop parameters (proportional gain and integration time). After optimization, users can see significant improvements by comparing the Trace curves before and after optimization, such as a significant reduction in overshoot and faster response speed.

4.2 Optimization of Induction Motor

For induction motors (vector control mode), the optimization process includes three key steps:

Motor data calculation (P340): Calculate equivalent circuit parameters (stator/rotor impedance, inductance, etc.) based on motor nameplate data. This process does not require the use of a frequency converter.

Static identification of motor data (P1910): By enabling the frequency converter, the system automatically calculates key parameters such as stator cold impedance, rotor cold impedance, and main inductance. During the identification process, the motor may rotate slightly, but there is no torque output at the shaft end.

Dynamic identification of motor data (P1960): In the unloaded or loaded state of the motor, the system automatically performs speed loop parameter optimization, acceleration pre control (P1496) calculation, and system moment of inertia identification. After the optimization is completed, the system will update the new parameters to the speed regulator.

4.3 Optimization of servo motor

For servo motors, S120 also supports data calculation and static identification. By correctly configuring motor data (such as P305 rated current, P311 rated speed, P314 rated torque, P316 maximum speed, P323 pole pairs, etc.), the system can automatically calculate other parameters required for normal motor operation (such as P341 moment of inertia, P350 stator impedance, etc.). For high-precision servo applications, it is recommended to combine Trace and Bode diagram tools to finely manually adjust the speed and position loops.

Basic positioning function

Starting from firmware version V2.4, SINAMICS S120 integrates powerful basic positioning functions, including jog, zero return, limit, program steps, and manual data input (MDI).

5.1 Activation and Settings

When configuring the driver unit offline, the basic positioning function needs to be activated in the configuration wizard. After activation, the project navigation bar will display options for "Technology/Basic Positioner" and "Position control". Users can set and debug the positioning function through the control panel or expert parameter table.

5.2 Jog (Jog)

The jog function supports two modes:

Speed mode: When the button is pressed, the axis runs at the set speed, and when the button is released, it stops.

Position mode: Press the button and the rear axle will automatically stop when it reaches the set target position.

The user needs to set the jog speed, acceleration, and deceleration, and associate the ON/OFF 1 enable signal (P840) with the external switch.

5.3 Return to Zero (Homing)

The zeroing function varies depending on the encoder type:

Absolute value encoder: Only a one-time calibration is required during the initialization phase to set the zero point coordinates, without the need for repeated zeroing.

Incremental encoder: supports active and passive zeroing. Active zeroing can be achieved through three methods: encoder zero flag, external zero flag, or proximity switch+encoder zero flag. By defining parameters such as search direction, search speed, and proximity switch, the system automatically performs the zeroing action. Passive zeroing refers to dynamically resetting the current position to zero during the operation of the shaft, without affecting the operating state.

5.4 Limit

S120 supports dual protection of soft limit and hard limit. The hard limit is triggered by the switch input signal (P2569/P2570), and the signal is low and effective; The soft limit is set to the forward/reverse position range through parameters P2578/P2579. When the axis reaches the limit, the system will stop at maximum deceleration (P2573).

5.5 Program Steps (Traversing Blocks)

The program step mode allows users to preset up to 64 positioning steps, each of which can set parameters such as position, velocity, acceleration, etc. The program steps can be selected through a combination of digital input signals and can be automatically executed in sequence or in single steps. This function is suitable for applications that require repeated execution of fixed path positioning.

5.6 Manual Data Input (MDI)

The MDI mode provides a flexible interface for real-time control of the upper computer. This mode supports two operating modes: