Firmware
≤
02.00 - DMS 2.1 EN - 03/2011
L
83
8400 motec | Software Manual
Motor control (MCTRL)
V/f characteristic control - energy-saving (VFCplusEco)
5.6.4.1
Improving the behaviour at high dynamic load changes
Due to the voltage reduction executed via the cos
ϕ
control, the motor may stall in the
Lenze setting in case of high dynamic load changes (dynamic load impulse from 0 to more
than 50 % rated motor torque).
An adaptation of the minimum voltage V/f (
) improves the stability in case of load
impulses.
In the Lenze setting, the minimum voltage V/f is set to 20 % for the highest energy
optimisation. With this setting, a dynamic load impulse from 0 to approx. 50 % rated
motor torque can be applied without the motor stalling.
An increase of the minimum voltage V/f to 70 % permits to apply a dynamic load
impulse from 0 to 100 % rated motor torque without the motor stalling. This reduces
the energy optimisation to be achieved by approx. 75 %.
A further increase of the stability at still higher dynamic load impulses can be achieved
by a further increase of the minimum voltage V/f, but means a further loss in energy
optimisation.
5.6.4.2
Adapting the slope limitation for lowering the Eco function
The ramp set in
for voltage reduction serves as slope limitation in order to prevent
that voltage is suddenly applied to the motor when the Eco function is deactivated.
Otherwise, the overvoltage limitation (Imax, Clamp) would be activated.
This ramp is, depending on the device, pre-initialised to approx. the triple rotor time
constant. An adapation of this parameter is not required.
When the Eco function is switched off, a quick reaction (high dynamic performance) is
required, but with a low current overshoot and a small torque jump. Thus, the Lenze
setting of
is a compromise regarding the switch-off of the Eco function (motor
voltage sub=0).
To increase the dynamics when switching off the Eco function:
Reduce
setting in
.
(Current compensation actions increase when the Eco function is switched off.)
In order to reduce current compensation actions when switching off the Eco function:
Increase
(The dynamics when switching off the eco function is reduced)
Note!
The energy optimisation can be switched off by setting the minimum voltage V/
f (
) to 100 %. Then, the behaviour corresponds to the V/f characteristic
control (VFCplus) with linear characteristic.
In case of applications with very high dynamic sudden load variations from the
unloaded operation, this motor control mode should not be used or the energy
optimisation should be switched off, since a motor stalling cannot be excluded.
Summary of Contents for 8400 motec Series
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