Siemens SINAMICS S120 Function Manual page 172

Vector control
4.1 Sensorless vector control (SLVC)
Extended method: Closed-loop controlled operation down to 0 Hz
The actual rotor position can be continuously determined down to 0 Hz (standstill). With
Siemens 1FW4 and 1PH8 torque motors, the load can be maintained at standstill or, from
standstill, the motor can accelerate any load up to rated torque.
When the function is activated, at low speeds, additional noise can be heard, depending on
the motor design.
The procedure is suitable for motors with internal magnets.
Figure 4-5 Zero point in closed-loop operation down to zero speed
Note
Only open-loop controlled operation is permitted when using a sine-wave filter.
Note
1FW4 torque motors
Siemens "1FW4" torque motors can be started from standstill and operated in the closed-
loop torque controlled mode. The function is activated with parameter p1750.5 = 1.
Third-party motors must be checked on a case-for-case basis.
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Function Manual, (FH1), 01/2013, 6SL3097-4AB00-0BP3
Drive functions