Siemens SINAMICS G130 - Page 342

Setpoint channel and closed-loop control
7.4 Vector speed/torque control with/without encoder
Inverter chassis units
342 Operating Instructions, 07/2016, A5E00331449A
Extended method: closed-loop controlled operation to zero speed
By superimposing high-frequency pulses on the driving fundamental voltage and evaluating
the resulting offset pulse in the machine current, it is possible to determine the continuous
rotor position up to frequency zero (standstill).
1FW4 and 1PH8 series Siemens torque motors can be started from standstill with any load
up to the rated torque or even hold the load at standstill.
The procedure is suitable for motors with internal magnets.
Note
Use of a sine-wave filter
If a sine
-wave filter is used, the open-loop controlled procedure should be used.
The following advantages are obtained by maintaining closed-loop controlled operation:
● No switchover required within closed-loop control (smooth switching, no discontinuities in
the torque).
● Sensorless closed-loop speed and torque control down to and including 0 Hz
● Higher dynamic performance when compared to open-loop controlled operation.
● Encoderless operation of drive line-ups (e.g. in the paper industry, master-slave
operation).
● Active (including hanging/suspended) loads down to zero frequency.
Supplementary conditions for the use of third-party motors:
● Experience shows that the procedure is very suitable for motors with magnets within the
rotor core (IPMSM - Interior Permanent Magnet Synchronous Motors).
● The ratio of stator quadrature reactance (Lsq): Stator direct-axis reactance (Lsd) must be
> 1 (recommendation: minimum > 1.5).
● The possible operating limits of the procedure depend upon up to what current the
asymmetrical reactance ratio (Lsq:Lsd) is retained in the motor. If the procedure should
be operable up to the rated motor torque, then the reactance ratio must be retained up to
the rated motor current.
A prerequisite for optimum behavior is the entry of the following parameters:
● Enter the saturation characteristic: p0362 - p0369
● Enter the load characteristic: p0398, p0399
Commissioning sequence for closed-loop controlled operation to zero speed:
● Run through the commissioning with motor identification at standstill.
● Enter the parameters for the saturation characteristic and the load characteristic.
● Activate closed-loop controlled operation to zero speed via parameter p1750 bit 5.