80 Program features
Example 1:
If you need to fix the switching frequency to a certain value as with some
external filters, e.g. with EMC C1 filters (see the hardware manual), set both the
reference and the minimum switching frequency to this value and the drive will retain
this switching frequency.
Example 2:
If the reference switching frequency is set to 12 kHz and the minimum
switching frequency is set to 1.5 kHz (or 1 kHz), the drive maintains the highest
possible switching frequency to reduce motor noise and only when the drive heats it
will decrease the switching frequency. This is useful, for example, in applications
where low noise is necessary but higher noise can be tolerated when the full output
current is needed.
Settings
Parameters
97.01
Switching frequency reference
(page
340
) and
97.02
Minimum
switching frequency
(page
340
).
Speed compensated stop
Speed compensation stop is available for example for applications where a conveyer
needs to travel a certain distance after receiving the stop command. At maximum
speed, the motor is stopped normally along the defined deceleration ramp, after the
application of a user defined delay to adjust the distance traveled. Below maximum
speed, stop is delayed still more by running the drive at current speed before the
motor is ramped to a stop. As shown in the figure, the distance traveled after the stop
command is the same in both cases, that is, area A + area B equals area C.
Speed compensation does not take into account shape times (parameters
23.32
Shape time 1
and
23.33
Shape time 2
). Positive shape times lengthen the distance
traveled.
Used
speed
A
Motor speed
Max.
speed
B
C
t
(s)
Area A + Area B = Area C
Stop
command
D1
D1 = Delay defined by parameter
21.31
D2 = Additional delay calculated by
speed compensated stop
D2
ACS380 FW.book Page 80 Friday, May 4, 2018 4:18 PM
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