Synchronous Motor: Pole Position Identification (Ppi) - Lenze i950 Commissioning Manual

12.4

Synchronous motor: Pole position identification (PPI)

For controlling a permanent-magnet synchronous motor, the pole position - the angle
between the motor phase U and the field axis of the rotor - must be known.
For Lenze motors with absolute value encoder or resolver, the pole position has already
•
been set correctly.
When incremental encoders are used (TTL or sin/cos encoders without absolute position
•
information), a pole position identification (PPI) is always required. This also applies to
Lenze motors.
NOTICE
The pole position identification (PPI) must only be executed
▶ for servo control with a synchronous motor of an original equipment manufacturer.
▶ for servo control with a synchronous motor and incremental encoders (TTL or sin/cos
encoder).
▶ after changes to the motor feedback system, e.g. feedback replacement.
The parameter settings for pole position identification are accessed in »EASY Starter« via the
following path:
Settings tab
•
Basic setting \ Motor feedback (A)
•
Three different identification methods are offered here:
360° electrical
•
With min. movement
•
Without movement
•
The criteria for selecting the most suitable identification method are presented below.
Selection criteria for using the suitable pole position identification
For identifying the pole position for the currently activated feedback, the following functions
are available which all provide almost the same result. Due to e.g. friction, bearing forces and
a trapezoidal field pattern, the results may differ from each other.
4Pole position identification (PPI) 360°
The motor must not be braked, blocked or mechanically driven during the pole position
•
identification! This function must not be used for hanging loads!
Especially in case of idling drives or drives with a low load (inertia / friction), this function
•
delivers the most accurate results.
4Pole position identification (PPI) with minimum movement
The motor must not be braked, blocked or driven during the pole position identification!
•
Thus, this function must not be used for hanging loads!
Regarding the accuracy, this function is in the middle range. A percentage increase of the
•
current amplitude can enhance the accuracy of the results if required.
4Pole position identification (PPI) without movement
In case of stalled motors (e.g. with hanging loads), only this function shall be used!
•
This function was developed for a wide range of motor characteristics. In case of some
•
motor types, however, the identified pole position angle may differ considerably from the
real pole position angle, so that a considerable loss in torque and greater motor losses may
occur. Thus, especially when using third-party motors, we recommend the execution of a
reference identification with an idling
^ 203
If the identified values of both processes differ from each other by more than 20°, please
contact Lenze.
Detailed information on the respective function can be found in the following subchapters.
Configuring the feedback system
Synchronous motor: Pole position identification (PPI)
^ 203
^ 207
^ 210
motor4Pole position identification (PPI) 360° .
201