Operation Without Speed Encoder - Siemens SIMOVERT MV Series Commissioning Instructions

4.3.7

Operation without speed encoder

For encoderless operation, there is no measuring equipment for the speed, and
this is why an artificial speed actual value is used, which is calculated from the
rotating frequency of the motor.
The controlled operating range therefore does not include n = 0 (zero speed) but is
only possible from a minimum frequency; the drive goes into the open-loop
controlled operating mode below this frequency:
Open-loop controlled operation
Closed-loop controlled operation
Open-loop controlled operation
Closed-loop controlled operation
The percentage refers to the rated motor frequency, which is set to 100 %. The
maximum frequency, clockwise and counter-clockwise is limited by the permissible
drive frequency; it may never exceed the permissible drive converter output
frequency.
The ramp-function generator is set, so that the drive can follow the ramp without
any following error.
At the transition from the open-loop controlled into the closed-loop controlled
operating range, the speed controller shouldn't generate any steps.
The voltage model flux should not manifest any amplitude changes > 10 % during
setting process! The frequency actual value must be smoothed.
Encoderless operation is pre-fed in the factory. Speed-controlled with encoder has
to be set using P602 = 0 (2.TRV.DP.FRE).
P602 = 1 (2.TRV.DP.FRE) enable encoderless operation
P391 = 1 (1.NRV1.C20.I1) enable acceleration pre-control
If, the required acceleration time should be so low for closed-loop controlled
operation, that breakaway is difficult, then the ramp gradient must be limited in the
open-loop controlled operating range using P355 (1.SWK.H14.X2). Setting range:
5 s - 3600 s.
The acceleration pre-control is calibrated at P358 (1.SWK.H200.X2) so that when
the drive accelerates uncoupled (uncoupled from the load) the integral component
of the speed controller remains extremely low (ideally, approximately zero).
When the drive is loaded (the load is known) the load torque can be pre-controlled
statically in order to support acceleration at P390 (1.NRV1.C70.X2). Setting range:
0 - 150 %. The pre-control is disabled for f > 8 % (or f < −8 %) as the speed
controller is then fully operational.
66
0 to −8 %
−8 % up to maximum speed, counter-
clockwise
0 to 8 %
8 % to maximum clockwise speed
Siemens AG
SIMOVERT MV Commissioning Instructions
6SE8004-0BH76