Lenze 8400 motec - Manual (Page 128)

5 Motor control (MCTRL)
5.9 Sensorless control for synchronous motors (SLPSM)
128 Lenze · 8400 motec · Reference manual · DMS 4.1 EN · 08/2013 · TD05
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The motor model-based speed monitoring requires a rotating machine. Thus, the operational
performance of the sensorless control for synchronous motors is divided into two categories:
1. Open-loop controlled operation (|n
setpoint
| < n
C00996
)
• In the range of low speeds, the speed of a synchronous motor is not possible. Thus, only an
adjustable and constant current is injected that enables an acceleration.
2. Closed-loop controlled operation (|n
setpoint
| > n
C00996
)
• In this range, the rotor flux position and the speed are reconstructed via an observer. The
control is carried out field-oriented. Only the current is injected that is needed for the
required torque.
[5-5] Operating ranges of the sensorless control for synchronous motors
The sensorless control for synchronous motors has similar advantages for the closed-loop
controlled operating range and the servo control (SC) for synchronous motors. Compared to
asynchronous motors, there are the following advantages:
• Higher power density of the motor
• Higher efficiency
• Limitation of the maximum torque in motor mode and generator mode in closed-loop
operating range
• Implementation of simple positioning
 Operation in motor mode (CW rotation),  Operation in generator mode (CCW rotation),
 Operation in motor mode (CCW rotation),  Operation in generator mode (CW rotation)
 Field weakening
 Closed-loop controlled operation
 Open-loop controlled operation
Œ  Ž  Œ
0 1
2 3
M
n