Speed Control Using Stator Phase-Angle Control - Siemens SIMOTRAS 6SG7050 Operating Instructions Manual

01.04
3.3.2

Speed control using stator phase-angle control

The amplitude of the fundamental wave of the supply voltage is changed using the stator phase-
angle control. With a constantly ascending ramp for the setpoint voltage from zero to maximum
activation, the control angle and therefore the voltage time-area are continually increased. This
increases the motor voltage (U
torque increases proportionally to U
Phase-angle control
Mains
Figure 3.3.2.1 Simplified drive diagram with stator phase-angle control and asynchronous
n
n
0
n
N
n
K
M
L
M
M
0
M *
A
Figure 3.3.2.2 Simplified characteristic curve of the asynchronous machine with stator phase-
M* = temporarily effective motor characteristic (dotted line) for a single squirrel-cage motor with
stator phase-angle control
M * = Acceleration torque of the drive provides the speed ramp-up. Derived from the present
B
difference M
as the shaded area in the figure.
M * = Start-up torque of the motor set by the stator phase-angle. In order to start, M
A
larger than the load torque M
SIEMENS AG 6SG7000-0BA76
SIMOTRAS HD Operating Instructions
) continually and the drive is thereby slowly accelerated. The motor
M
M
Motor
machine under load
Possible load characteristic M
M*
M *
B
With direct start-up:
- simple squirrel-
cage rotor
- double squirrel-
cage rotor
M M
A S
angle control for a direction of rotation/torque direction
– M . The acceleration torque M
M L
2
.
Load
M
n
M
M
3 ~
M
L
L
Motor characteristics
n = Synchronous speed
0
n = Speed at nominal working point
N
n = Speed at pull-out torque
K
M = Pull-out torque of simple squirrel-cage rotor
K
M = Torque at dip
S
M = Start-up torque of simple squirrel-cage rotor
A
without stator phase-angle control
M = Load torque
L
M = Motor torque
M
M * = Start-up torque with stator phase-angle control
A
M* = Temporary motor characteristic
M * = Acceleration torque
B
M
M
K
effective across the entire range is shown
B
.
L
Description
* must be
A
3-3