Lenze 8400 TopLine - Manual (Page 276)

5 Motor control (MCTRL)
5.10 Parameterisable additional functions
276
Lenze · 8400 TopLine · Reference manual · DMS 6.0 EN · 06/2014 · TD05/TD14
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5.10.9 Field weakening for synchronous motors
This function extension is available from version 02.00.00!
[5-25] Voltage/speed characteristic with switched-on field weakening
[5-26] Calculation of the maximally reachable speed with switched-on field weakening

Note!
Function only possible with:
• Servo control (SC)
• Sensorless control for synchronous motors (SLPSM)
(from version 10.00.00)
In the Lenze setting, the field weakening for synchronous motors is activated in
C00079/4 .
• If a high energy efficiency is required, keep the field weakening switched off or restrict
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!
• The use of a temperature feedback via KTY is recommended.  Motor temperature
monitoring (KTY) ( 373)
 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
⋅
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