Honeywell SmartVFD HVAC MR4 User Manual page 149

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M3.12.2.7 S
LEEP FREQUENCY LIMIT
M3.12.2.8 S
LEEP DELAY
M3.12.2.9 W
AKE
This function will put the drive into sleep mode if the frequency stays below the sleep limit for
a longer time than that set with the Sleep Delay (M3.12.2.8). This means that the start com-
mand remains on, but the run request is turned off. When the actual value goes below, or
above, the wake-up level depending on the set acting mode the drive will activate the run re-
quest again if the start command is still on.
Frequency
Sleep limit
(M3.12.2.7)
M3.12.4.1 F
EEDFORWARD FUNCTION
Feedforward usually needs accurate process models, but in some simple cases a gain + offset
type of feedforward is enough. The feedforward part does not use any feedback measurements
of the actual controlled process value (water level in the example on page 78). The feedforward
control uses other measurements which are indirectly affecting the controlled process value.
Example 1:
Controlling the water level of a tank by means of flow control. The desired water level has been
defined as a setpoint and the actual level as feedback. The control signal acts on the incoming
flow.
The outflow could be thought of as a disturbance that can be measured. Based on the mea-
surements of the disturbance, we can try to compensate for this disturbance by simple feedfor-
ward control (gain and offset) which is added to the PID output.
This way the controller would react much faster to changes in the outflow than if you just had
measured the level.
1
1
- 1
UP LEVEL
Actual value
Wake-up level
(M3.12.2.9)
Sleep delay
(M3.12.2.8)
Regulating mode
Figure 18. Sleep limit, Sleep delay, Wake-up level
Sleep Regulating mode
HVAC A
PPLICATION
100K19.fh11