Direction Reversal Without Changing The Setpoint - Siemens SINAMICS S120 Function Manual

7.10

Direction reversal without changing the setpoint

The direction of rotation of the motor can be reversed using the direction reversal via p1821
without having to change the motor rotating field by interchanging two phases at the motor
and having to invert the encoder signals using p0410.
The direction reversal via p1821 can be detected as a result of the motor direction of
rotation. The speed setpoint and actual value, torque setpoint and actual value and also the
relative position change remain unchanged.
The direction change can be identified as a result of the phase voltage (r0089). When the
direction reverses, then the absolute position reference is also lost.
For vector control, in addition, the output direction of rotation of the converter can be
reversed using p1820. This means that the rotating field can be changed without having to
interchange the power connections. If an encoder is being used, the direction of rotation
must, when required, be adapted using p0410.
Note
Rotating/moving measurement for motor data identification of SERVO drives
Use parameter p1959[0...n].14/15 = 0 to activate a direction inhibit for the rotating
measurement for motor data identification where necessary. The direction inhibit should be
deactivated with p1959[0...n].14/15 = 1 for complete and accurate identification of the motor.
Features
● No change to the speed setpoint and actual value, the torque setpoint and actual value
and the relative position change.
● Only possible when the pulses are inhibited
Excessively high torque due to an inappropriate phase sequence of the motor after
direction reversal
If a drive is synchronized to the line supply, when the direction is reversed, high torques
can be generated when connecting to the line supply if the phase sequence of the line
voltage does not match the phase sequence of the rotating motor. This high torque can
destroy the coupling between the motor and load and therefore result in death or severe
injury.
• As a consequence, for this constellation, check the phase sequence of the VSM wiring
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
WARNING
and correct if necessary.
7.10 Direction reversal without changing the setpoint
Basic functions
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