Siemens SINAMICS PERFECT HARMONY GH180 Function Manual page 324

Advanced Operating Functions
8.22 High Performance Control
Synchronous Motors (SM) and Induction Motors (IM) may require a high starting torque mode:
• SMs have an externally generated flux source that can be pulsed to provide enough feedback
to lock onto the flux angle at standstill. SMs have poor starting torque characteristics.
• IMs have a flux created through coupling across the air gap and can be controlled directly.
• In V/Hz control mode SMs and IMs require a high starting torque mode: to overcome static
friction (stiction) that is high in either the motor or the load; or when a large inertial load is
connected; or when operating a motor on long cables in which a significant amount of load
impedance is in the cables.
Figure 8-28 High Starting Torque Mode Example System
HST Secondary Current Level
The HST secondary current level is for implementation after the initial starting state, and before
the control loops are enabled to prevent saturation of transformers used between the output of
the drive and the connected motor due to the high currents and associated voltages. Saturation
can cause distortion and excessive losses. Once the load has begun to move, the high torque is
no longer needed and so then the secondary current level is adequate.
The secondary current level is implemented through parameter Trq Current 2 (2965).
Figure 8-29
322
Modified High Starting Torque Mode
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