Technical data

Drive functions
7.1 Servo control
Function Manual
Function Manual, 06/2012, 6SL3097-4AB10-0BP4
161
7.1.13 Pole position identification
Description
For synchronous motors, the pole position identification determines its electrical pole
position, that is required for the field-oriented control. Generally, the electrical pole position is
provided from a mechanically adjusted encoder with absolute information. In this case, pole
position identification is not required. For the following encoder properties, pole position
identification is not required:
● Absolute encoder (e.g. EnDat, DRIVE-CLiQ encoder)
● Encoder with C/D track and pole pair number ≤ 8
● Hall sensor
● Resolver with a multiple integer ratio between the motor pole pair number and the
encoder pole pair number
● Incremental encoder with a multiple integer ratio between the motor pole pair number and
the encoder pulse number
The pole position identification is used for:
● Determining the pole position (p1982 = 1)
● Determining the angular commutation offset during commissioning (p1990 = 1)
● Plausibility check for encoders with absolute information (p1982 = 2)
WARNING
When the motors are not braked, the motor rotates or moves as a result of the current
impressed during the measurement. The magnitude of the motion depends on the
magnitude of the current and the moment of inertia of the motor and load.
Notes regarding pole position identification
The relevant technique can be selected using parameter P1980. The following techniques
are available for pole position identification:
● Saturation-based 1st+ 2nd harmonics (p1980 = 0)
● Saturation-based 1st harmonics (p1980 = 1)
● Saturation-based, two-stage (p1980 = 4)
● Saturation-based (p1980 = 10)
The following supplementary conditions apply to the saturation-based motion technique:
● You can use the techniques for both braked and non-braked motors.
● It can only be used for a speed setpoint = 0 or from standstill.
● The currents specified (p0325, p0329) must be sufficiently large to provide a meaningful
measuring result.