Lenze i550

10.2 Sensorless control for synchronous motor (SL-PSM)
The sensorless control for synchronous motors is based on a decoupled, separated control of
the torque-producing current and the current in eld direcon. In contrast to the servo con-
trol, the actual speed value and rotor posion are reconstructed via a motor model.
NOTICE
In case of this motor control type, an adjustable, constant current is injected in the lower
speed range. If this current is higher than the rated motor current, the motor may heat up in
the lower speed range. This eect increases if the motor is operated in the lower speed range
for a longer period of me.
Possible consequence: Destrucon of the motor by overheang
▶
Do not operate the motor for a longer period of me in the lower speed range.
▶
For detecng and monitoring the motor temperature, we recommend a temperature feed-
back via PTC thermistor or thermal contact. 4Motor temperature monitoring ^ 234
Precondions
The sensorless control for synchronous motors (SL-PSM) is possible up to a rated power of
maximally 22 kW.
Details
Pole posion idencaon (PLI)
•
For controlling a permanent-magnet synchronous motor, the pole posion - the angle
between the motor phase U and the eld axis of the rotor - must be known.
•
If the drive is at a standsll, the "pole posion idencaon (PLI)" funcon is immediately
acvated aer the inverter is enabled. 4Synchronous motor: Pole posion idencaon
(PPI) ^ 167
Conguring the motor control
Sensorless control for synchronous motor (SL-PSM)
170