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5
Motor control (MCTRL)
5.8
Sensorless control for synchronous motors (SLPSM)
228
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
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5.8.6
Field weakening for synchronous motors
This function extension is available from version 11.00.00!
[5-17] Voltage/speed characteristic with switched-on field weakening
[5-18] 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
.
• If a high energy efficiency is required, keep the field weakening switched off or restrict
the field weakening operation via
Stop!
In the field weakening operation, a current is injected into the synchronous motor even
in idle state which can rise to maximum current (
).
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.
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
U
motor
n
max
n
nenn_mot
800V
2 U
nenn_mot
⋅
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⋅
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