Lenze i700 - Defining the Behaviour at the Current Limit (Imax Controller)

5 Motor control & motor settings
5.14 Parameterising the V/f characteristic control
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Lenze · i700 servo inverter · reference manual · DMS 3.0 EN · 06/2016 · TD06
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5.14.5 Defining the behaviour at the current limit (Imax controller)
The maximum output current or the current limit is determined by the object "Max. current"
(0x6073
or 0x6873 for axis B). In case of the V/f characteristic control, an lmax controller is
implemented for complying with this limit. If the motor current exceeds the set maximum value,
the lmax controller is activated.
• The Imax controller changes the field frequency so that the motor current does not exceed the
current limit. In motor mode, the frequency is reduced and in generator mode it is increased.
• The gain and reset time of the Imax controller can be parameterised.
• For the automatic calculation of these two parameters, the "VFC: Calculate Imax controller
parameters" function is provided via object 0x2822
(or 0x3022 for axis B).
Optimising the Imax controller
The automatic calculation serves to determine starting parameters of the Imax controller which are
sufficient for many applications. Thus, an optimisation is not required for most of the applications.
The parameters of the Imax controller have to be adapted if
• a power control is implemented with great moments of inertia.
Recommendation:
Step 1: Increase reset time in 0x2B08:2 (or 0x3308:2 for axis B)
Step 2: Reduce gain in 0x2B08:1
(or 0x3308:1 for axis B)
• vibrations occur with V/f characteristic control during the operation of the Imax controller.
Recommendation:
Step 1: Increase reset time in 0x2B08:2 (or 0x3308:2 for axis B)
Step 2: Reduce gain in 0x2B08:1
(or 0x3308:1 for axis B)
• overcurrent errors occur due to load impulses or too high acceleration/deceleration ramps.
Recommendation:
Step 1: Reduce reset time in 0x2B08:2 (or 0x3308:2 for axis B)
Step 2: Increase gain in 0x2B08:1
(or 0x3308:1 for axis B)