KEB COMBIVERT F5-A, Applications Manual, Page: 266 / 552

Page 7.10 - 6 COMBIVERT F5-A, -E, -H © KEB, 2012-10
Current control, -limiting and switching frequencies
If a carrier frequency is selected in parameter uF.11 that is higher than the rated value, an automatic "derating",
i.e. reduction of the switching frequency is carried out depending on the temperature, output frequency and
utilization of the motor. This carrier frequency change-over is generally not good for the control characteristic
of the drive. Therefore the carrier frequency uF.11 should be preferably equal to the rated switching frequency.
However the effects of the deratings can be neglected in many applications.
7.10.4 Voltage reserve for the non-prioritized current controller
Addr. Parameter Name Default value Wet
1127h dS.39 reserved modulation factor 0% 0...50%
Introduction of a minimum voltage reserve (dS.39, default 0%) for the non-prioritized current controller. Since
the current controller in the D-axis has priority by default, a reserve is assigned to the current controller in the
Q-axis. This ensures that the drive remains controllable in the field weakening if the max. permissible Id current
(dS.13) is selected too high.
U
maxGrad
maximum modulation factor (dS.04, 100% or 110%)
U
maxPriorGrad
maximum modulation factor of prioritized voltage components
U
maxNotPriorGrad
modulation factor of non-prioritized voltage components
U
maxPriorGrad
= U
maxGrad
- dS.39
U
maxNotPrior
=
√
(U²
maxGrad
- U²
maxPriorGrad
)