KEB COMBIVERT F5-A Applications Manual page 145

10: High resolution in %
(ru.63)
Other functions like quick stop, fixed frequency, or positioning have priority over "standard operation" and can
therefore lead to different speed setpoints than selected in oP.00 .
The following speed setpoint limiting blocks can change the setpoint.
Direct analog setpoint setting (AN1 direct)
The cycle time of the software is 1 ms. During this time the analog input/output status is updated once. Addi-
tionally the inverter requires a processing time of 1... 3 ms before the new setpoint value is calculated. If the
inverter is used as secondary final control element of a superior control, this time can impair the dynamics of
the entire closed-loop control system.
In such cases the analog setpoint value can be processed directly to the control processor (direct setpoint
adjustment). Thus a scan time of 250 µs is possible. To enable this fast response to an analog setpoint value,
some restrictions must be accepted:
• The calculation formula of the analog setpoint value changes. Parameters oP.06 / oP.07 are without influence
on the setpoint calculation.
percentage analog value = (analog value/10V x 100% - An.06) x An.05
This value is limited to+/- 100%.
n = limited analog value in percent x oP.10
set
This value is limited with oP.14 for for both directions of rotation.
• The reference limitations oP.06 / oP.07 / oP.11 do not have any function; the absolute max. reference is only
limited by oP.14 (for both directions).
• The acceleration / deceleration and S-curve time have no effect; it is operated internally without ramps.
• The parameters An.01...04 and An.07...09 are without any function
• The stop position controller cannot be activated.
High resolution reference setting
The setpoint setting with the settings oP.00 = 0...9 is 16 Bit wide. This results in a maximum resolution of 0.125
rpm in 4000-rpm mode (ud.02 = 4 and 8).
For applications needing a higher resolution, the high resolution setpoint setting was introduced. Here, the
setpoint is set as a 32-Bit-value.
Since only a 16-Bit-value can be output, the low-order 16 bits of the ramp output value are upsampled. On
overrun, the base value is increased for one cycle (1 ms) (by 0.125 rpm in 4000-rpm mode). These setpoint
fluctuations are smoothed mechanically, leading to the higher average resolution.
To achieve the highest possible resolution for the application, two parameters can be used:
oP.64 Ref. value high-resolution
© KEB, 2012-10 COMBIVERT F5-A, -E, -H
Setpoint, rotation- and ramp setting
Setting of the speed setpoint value
via oP.63 "reference value high-reso-
lution". This mode must be used if the
standard speed resolution is insuffici-
ent.
Configuration of the high resolution
and calculation of the speed setpoint
from parameters oP.63 / oP.64 see in-
structions.
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