Technical data

ManualsBrandsDanfoss ManualsMedia ConverterVLT 5000 FLUX

MG.10.Q1.5B – VLT is a registered Danfoss trade mark

VLT 5000/5000 FLUX SyncPos Quick-Setup

Vmax: Is the maximum encoder velocity. The

unit is RPM. If the SyncPos feedback encoder is

motor mounted then parameter 205 must be

equal to Vmax.

FFVEL is now optimized, save the current value.

Please note that some high inertia systems do

not allow the use of FFVEL.

4. In systems with large inertia and/or rapid changes

in the reference velocity it is a good idea to use

and optimize the

Acceleration feed-forwardAcceleration feed-forward

Acceleration feed-forward

control (make sure the inertial load is connected

when optimizing this parameter):

Step 1)

Execute a "TESTRUN" with KPROP=0,

KDER=0, KINT=0, FFACC=0 and FFVEL at the

optimized value calculated above. Use the

highest possible acceleration setting. If

RAMPMIN (31) is adjusted properly an

acceleration value of 100 and a deceleration

value of 100 should be sufficient. Start out with

a low setting of FFACC approx. 10.

Step 2)

View the velocity profiles: If during acceleration

the actual velocity is constantly lower than the

reference velocity profile, then click "REPEAT"

and set a higher value of FFACC. Then execute

"TESTRUN" again.

Step 3)

Run successive TESTRUNs until the two velo-

city profiles shown in the TESTRUN graph have

similar ramp-up and ramp-down curves.

Step 4)

FFACC is now optimized, save the current

value.

5. Next step is finding the maximum stable value

of the

Proportional factoProportional facto

Proportional factor in the PID controller:

Step 1)

Execute a "TESTRUN" with KPROP (calculated

FFVEL/50), KDER=0, KINT=0. Set FFVEL and

FFACC at the optimized values found above.

Step 2)

View the velocity profile. If the velocity profile

isn't oscillating then click "REPEAT" and

increase KPROP else reduce KPROP and

repeat.

Step 3)

Run successive TESTRUNs until the actual

velocity profiles is oscillating mildly. Save this

value.

6. In order to dampen the oscillations created

by the KPROP-part of the controller, the

Derivative factorDerivative factor

Derivative factor should now be optimized.

Step 1)

Execute a "TESTRUN" with KINT=0 and

KDER=5*KPROP. Set FFVEL, FFACC and

KPROP at the optimized values found above.

Step 2)

Run successive TESTRUNs with increasing

values of the KDER factor. At first the oscilla-

tions will gradually reduce. Stop increasing

KDER when the oscillations begin to

increase.

Step 3)

Save the last value of KDER.

7. In any system that requires a close to zero

steady-state error, the integration part of the

controller must be used. Setting this

parameter though is a trade-off between

achieving zero steady-state error fast and

increasing overshoot and oscillations in the

system.

8. If you are using the integration part of the

PID controller, remember to reduce the

KILIM as much as possible (without losing

the KINT-effect of course) in order to reduce

oscillations and overshoot as much as

possible.

9. Reduce the BANDWIDTH only if the system

has a tendency to vibrate. With a properly

optimized open-loop control BANDWIDTH

could be reduced to as little as 6 to 12 %.

10. Set the POSERR (15) parameter back to

normal e.g. 20000.

"TEST PARAMETER" → "SAVE"

Once you have concluded the "TESTRUN"

→→

→

"SAVE"

the new parameters as the user parame-

ters. Thus, these parameters are saved in the

controller and in the future will be used for all

programs.

■ What to do if...

... there is a tendency towards instability

In the event of a strong tendency towards insta-

bility reduce the proportional and derivative

factors again, or reset the integral factor.

... stationary precision is required

If stationary precision is required then you must

increase the integral factor.

10 steps to optomise the PID loop