Lenze 8400 motec - Manual (Page 141)

Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05 141
5 Motor control (MCTRL)
5.9 Sensorless control for synchronous motors (SLPSM)
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
5.9.5 Field weakening for synchronous motors
This function extension is only available from version 04.00.00!
[5-8] Voltage/speed characteristic with switched-on field weakening
[5-9] Calculation of the maximally reachable speed with switched-on field weakening

Note!
In the Lenze setting, the field weakening for synchronous motors is activated in C00079/
4 .
• If high energy efficiency is required, deactivate the field weakening or limit the field
weakening operation via C00938 .

Stop!
In the field weakening operation, a current is injected into the synchronous motor even
in idle state which can rise to maximum current ( C00022 ).
Ensure that this no-load current does not cause the motor to be heated impermissibly!
• We recommend using a temperature feedback via PTC or thermal contact.  Motor
temperature monitoring (PTC) ( 176)
 Armature control range
 Field weakening range
• When field weakening is switched on, the motor
magnetising current is increased from 0 A to the maximally
effective magnetising current via an internal control loop
when the voltage limit is reached.
• As a result, a higher speed can be reached at the same
motor voltage or DC-bus voltage.
n Œ 
U
motor
n
max
n
nenn_mot
800V
2 U
nenn_mot
⋅
-------------------------------------- ⋅ =