Siemens SINAMICS PERFECT HARMONY GH180 - Synchronous Motor Control (SMC)

4.7.6 Synchronous Motor Control (SMC)
For synchronous motor control (SMC), the drive is equipped with a 󹪝eld exciter that usually
consists of a SCR based current regulator. The 󹪝eld exciter operates to maintain a 󹪝eld current
level that is commanded by the 󹪞ux regulator. An example application for a brushless
synchronous motor is shown in the 󹪝gure below.
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Figure 4-5 Drive Arrangement for Synchronous Motor with AC Brushless Exciter
The 󹪝gure shows a brushless synchronous motor with the static exciter wound for 3-phase AC in
the range of 350 to 400 volts. If this is not the case, then a transformer is needed between the
auxiliary power and the 󹪝eld exciter. The circuit wheel needs only a recti󹪝er.
Motor Protection
The control provides for minimal motor protection when the motor is connected to the drive. For
a system that employs drive, not cell, bypass, external protection of the motor is required. The
control will trip the drive on a loss of 󹪝eld fault if the motor draws excessive reactive current,
which will occur when the exciter fails full on or o󹪜. An external means to disconnect the exciter
power from the 󹪝eld is required to fully protect the motor.
Flux regulator implementation
The overall control strategy is similar to OLVC, except for the 󹪞ux regulator implementation.
Refer to Figure Vector Control Algorithms. For synchronous motors, the 󹪞ux regulator provides
two current commands, one for the 󹪝eld exciter current, and another for the magnetizing
component of stator current.
NXGPro+ Control Description
4.7 Control Modes
NXGPro+ Control Manual
52 Operating Manual, A5E50491925A