NORD Drivesystems BU0510 - Manual (Page 34)

POSICON position control for NORD frequency inverters, SK 530E and above
34 Subject to technical alterations BU 0510 GB-3911
3.7 Position control
The position control functions as a P- feedback loop. The setpoint position and the actual position are
continuously compared with each other. The setpoint frequency is formed by the multiplication of this
difference with the parameter P611 "Position Control P". This value is then limited to the "Maximum
Frequency" parameterised in parameter P105.
A path distance is calculated from the "Braking Time" parameterised in parameter P103 and the current speed.
Without taking the distance calculation into account by means of the braking time, the speed would normally
be reduced too late. Exceptions to this are highly dynamic applications with extremely short braking and
starting times and applications in which only very small path increments are specified.
As a further parameter, a starting point for slow travel can be set in parameter P612 "Size of Target Window".
Within the target window the setpoint frequency is limited to the frequency set in parameter P104 "Minimum
Frequency". This frequency can not fall below 2 Hz. For applications with greatly fluctuating loads and without
speed regulation, a creep path can be parameterised by means of this parameter.
The parameter P612 "Size of Target Window" does not have an effect on the relay/output message "Position
Reached".
Overview of position control:
Fig. 8: Overview of position control
Run with max.
frequency
Max.
Min.
Frequency
(*) Time determined by
"Pos. window"
Start-up
time
Run with min.
frequency
Time
Braking
time
(*)
P position control