Selecting The Control Mode - Siemens SINAMICS G120C Getting Started

4.2.2

Selecting the control mode

Criteria for selecting either V/f control or vector control
Application
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examples
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Motors that can be
operated
Properties of
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closed-loop motor
control
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Max. output
frequency
SINAMICS G120C converter
Getting Started, 04/2014, FW V4.7, A5E34264105B AA
U/f control or FCC (flux current control)
Pumps, fans, and compressors with flow
characteristic
Wet or dry blasting technology
Mills, mixers, kneaders, crushers, agitators
Horizontal conveyor technology (conveyor
belts, roller conveyors, chain conveyors)
Basic spindles
The rated current of the motor must lie in the range of 13 % ... 100 % of the rated current of the
The closed-loop control is insensitive to
inaccurate motor data settings, e.g. the
motor temperature
Can be commissioned with just a few
settings.
Responds to speed changes with a typical
settling time of 100 ms ... 200 ms
Responds to load surges with a typical
settling time of 500 ms
U/f and FCC are suitable for the following
cases:
– For power-up times 0 → rated speed >
2 s
– For applications with increasing load
torque without load impulses
240 Hz
4.2 Commissioning with BOP-2 operator panel
Vector control without an encoder
Pumps and compressors with displacement
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machines
Rotary furnaces
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Extruder
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Centrifuge
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inverter.
The vector control makes highly efficient use of
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the power module, the motor and the
mechanical system (95% of the line voltage).
The vector control responds to speed changes
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with a typical settling time of < 100 ms.
The vector control responds to load impulses
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with a typical settling time of 20 ms.
The vector control is required in the following
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cases:
– For power-up times 0 → rated speed < 2 s
– For applications with fast and high load
impulses
– For heavy duty starting using ≤ 90 % of the
stall torque of the motor
Vector control typically achieves a torque
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accuracy of ± 5 % for 10 % ... 100 % of the
rated speed
Commissioning
200 Hz
35