Selecting The Control Mode - Siemens SIMATIC ET 200pro Series Operating Instructions Manual

6.3.2

Selecting the control mode

Criteria for selecting either U/f control or vector control
Application exam-
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ples
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Properties of
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closed-loop motor
control
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Max. output fre-
quency
SIMATIC ET 200pro FC-2 converter
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34257324B AE
U/f control or flux current control
Pumps, fans, and compressors with flow
characteristic
Wet or dry blasting technology
Horizontal conveyor technology (conveyor
belts, roller conveyors, chain conveyors)
Basic spindles
The closed-loop control is insensitive to
inaccurate motor data settings, e.g. the mo-
tor temperature
Can be commissioned with just a few set-
tings.
Responds to speed changes with a typical
settling time of 100 ms ... 200 ms
Responds to load surges with a typical set-
tling time of 500 ms
U/f and FCC are suitable for the following
cases:
– For ramp-up times 0 → rated speed > 2 s
– For applications with increasing load
torque without load impulses
550 Hz
6.3 Preparing for commissioning
Vector control without an encoder
Pumps and compressors with displacement
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machines
Extruder
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The vector control uses the converter, the mo-
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tor and the mechanics highly efficiently (maxi-
mum motor voltage = 95% of the mains
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 ramp-up times 0 → rated speed < 2 s
– For applications with fast and high load im-
pulses
– For heavy duty starting using ≤ 90% of the
stall torque of the motor
Vector control typically achieves a torque accu-
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racy of ± 5% for 10% ... 100% of the rated
speed
240 Hz
Commissioning
75