5 Motor control (MCTRL)
5.8 Sensorless control for synchronous motors (SLPSM)
230
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
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•In C000937/1
, the actually used maximally effective field-producing motor current is displayed.
• With switched-on and active field weakening: 0.00 A ... -x.xx A
• With sensorless control for synchronous motors (SLPSM), the injected current is displayed in
open-loop controlled operation: 0.00 A ... +x.xx A
• If neither field weakening nor open-loop controlled operation are active,e "0.00 A" is
displayed.
Example: Voltage increase in the DC bus when field weakening is switched off
(For instance by an active setting of the controller inhibit or by tripping a fault or error at high motor
speed.)
[5-20] Example: Possible DC-bus voltage > 800 V if field weakening gets lost
Note!
If a Lenze motor is used:
The inverter is automatically parameterised so that field weakening operates optimally
and the maximally permissible speed is monitored.
Stop!
If an OEM motor is used:
If pulse inhibit is set in the inverter, the DC bus is loaded with the voltage that
corresponds to the current speed of the machine.
Since with switched-on field weakening higher speeds can be achieved at a
correspondingly higher rotor voltage of the motor, the DC bus can be loaded to a voltage
higher than the set DC-bus voltage in case of pulse inhibit and a currently high motor
speed and even exceed the maximally permissible voltage of 800 V!
For device protection, either use a brake chopper or parameterise the motor speed
monitoring via C00965
in such a way that only a maximum speed is possible which
would be also reachable without field weakening with a DC-bus voltage of = 800 V.
Motor speed monitoring
( 310)
Field weakening Speed n Motor voltage peak value
Switched off 4000 rpm 560 V
5700 rpm 800 V
6000 rpm
840 V
Switched on 6000 rpm 560 V
• If pulse inhibit occurs at 6000 rpm and switched-on field
weakening, the DC bus is loaded to more than 800 V ().
• A speed limitation to 5700 rpm is required since this speed
causes a DC-bus voltage of 800 V if field weakening is
switched off.
n
U
4000
840 V
560 V
6000
> 800 V
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