Lenze i950 Series, Manual

Page: 271 / 500

13.6.5.6 PSM field weakening controller
The inverter control enables a synchronous motor to be operated outside the voltage range. If
a motor is selected in the »EASY Starter«, the control is parameterised automatically.
Improve the transition from the base speed range to field weakening by activating the current
controller: feedforward control parameter.
4
0x2941
•
The current controller precontrol is defined via the following parameters:
• Motor parameter: stator resistance
4
0x2C01:002
• Motor parameter: stator leakage inductance
4
0x2C01:003
•
Motor parameter (PSM): back EMF constant
4
0x2C03:001
•
If you want to operate a third-party motor in the field weakening range, you have to deter-
mine the parameters previously mentioned
Operation of synchronous motors outside the voltage range:
If pulse inhibit is set in the inverter, e.g. in case of an inverter disable or an error,
the DC bus is loaded in accordance with the current speed (see equation).
• At high speed and outside the voltage range, the terminal voltage can be
higher than the mains voltage!
• In order to prevent the DC bus from being loaded impermissibly high, connect
a brake chopper to the DC bus!
The terminal voltage corresponds to the following equation
K
U = n * N
M
U
n
V
K
Terminal voltage
n Speed
V
rated
Rated mains voltage
n
m
Rated motor voltage
•
Mains settings: rated mains voltage
4
0x2540:001
•
Motor parameter: rated speed
4
0x2C01:004
Delaying the buildup of field weakening
With the default setting (5 %), field weakening is initiated, thus ensuring that a punctual
buildup of the field weakening current shortly before the voltage threshold is reached.
In the case of synchronous motors, setting the Voltage reserve range parameter may bring
about a delayed start of field weakening for synchronous machines, e.g in order to slightly
reduce the thermal load of the motor.
4
0x29E4
Configuring the motor control
Options for optimising the control loops
Motor control settings
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