Closed-Loop Controlled Operation Down To F = 0 Hz With Test Signal - Siemens SINAMICS S120 Function Manual
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Note
Synchronous reluctance motors are considered to be synchronous motors
Generally, the data for "Synchronous motors" provided in the SINAMCS S120 Manuals also
applies to "Synchronous reluctance motors". Any deviating behavior/response of
synchronous reluctance motors is always explicitly specified.
Features
For the motor type RESM in the default configuration (without test signal), at low speeds the
system changes over into speed-controlled operation is also started in this way. The load
torque requirement expected must be known for open-loop speed controlled operation, and
can be parameterized using p1610 and p1611.
When reaching the voltage limit (depending on the load and speed), the motor flux is
appropriately reduced (field weakening). Depending on the torque demanded, the required
motor current increases up to the available current limit. If the speed is then to increase
further, in order to maintain the voltage limit, the current must be reduced to below the
available current limit. In this range, the motor power available is therefore solely limited by
the available voltage; for synchronous reluctance motors, as a result of the saturation
attributes, it is slightly below that for induction motors.
5.2.7.2
Closed-loop controlled operation down to f = 0 Hz with test signal
Due to the magnetically anisotropic rotor, sensorless field-oriented operation can be
continued until standstill (f = 0 Hz) in the synchronous reluctance motor. A replacement of
the field orientation at low speed in an open-loop mode, as physically required with other
machines, can thus be omitted in the synchronous reluctance motor.
To determine the rotor position and speed from voltage and current, not only their large
signal levels are used. Additive small excitation pulses are superimposed on the driving
fundamental voltage and the resulting current changes, which are dependent on the rotor
position, are evaluated.
Functionally, the process permits a behavior that is completely equivalent to control
operation with speed-position sensor. For example, sensorless torque control can be used
without limiting the speed range. The achieved dynamics are only insignificantly reduced
compared to operation with sensor for the vast majority of vector applications.
Requirements
● Vector control
● License: Advanced synchronous reluctance control
● Limited number of axes (see Chapter "Overview of system limits and system utilization
(Page 1004)")
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
5.2 Vector control without encoder (SLVC)
Vector control
215
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