5 Motor control (MCTRL)
5.9 Servo control (SC)
252
Lenze · 8400 HighLine · Reference manual · DMS 12.0 EN · 06/2017 · TD23
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5.9.4.7 Optimising the behaviour of the asynchronous motor in the field weakening range
The behaviour in the field weakening range is influenced by:
• the field controller
• the field weakening controller
• the field feedforward control unit
• adaptive adaptation of the P component of the field and speed controllers
• An additional limitation of the I component of the controller when the voltage limit is reached
Note!
By default, these control parts are called every 1 ms. However, the 1-ms cycle is not
always sufficient to achieve an optimum jerk-free transition to the field weakening
range.
From version 14.00.00, the control parts can be called for an optimum jerk-free
transition to the field weakening range in a 500-
μs cycle. For this purpose, bit 5 has to be
set to "1" int in C02864/1
.
• With this setting, C00015
and C00576 do not have any influence anymore on the field
feedforward control.
• We recommend this setting for new applications.
• In existing applications, this setting may require an increase of the reset times of the
field weakening controller (C00578
) and the field controller (C00078) by the factor 2
in order to achieve a stable operation.
In general, these settings are pre-optimised so that further optimisation is not required.
Optimisation for special motors (e.g. mid-frequency motors) or for motors whose power
is not adapted can be carried out according to the algorithms shown in the following
sections.
From version 16.00.00 onwards, the dynamics of the field weakening control can be
improved with C02864/1
(bit 9 = 1) by admitting also negative setpoints of the field
current controller at the field controller output. Please note that this setting may cause
higher torque peaks which can be reduced again by decreasing the field weakening
controller gain ( C00577
) or increasing the reset time (C00578).
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