Position Controls
New functions
Special features
with Profibus-DP interface
with PROFIdrive interface
with CANopen interface
with encoder
with Closed Loop control

Eurocard format
for 19 inch mountage

Panel mount / 19 inch rack system
with integrated power supply

WSERS – Position control
in compact housing

Overview programming
with PC or SERS Programmer
SERS Programmer 2
Examples programming SERS drives
    home     products     position controls    SERS with closed loop control
    SERS with Closed Loop control
      The SERS/WSERS is available optionally with Closed Loop control. The stepper motor must be
a STÖGRA type with adjusted H500 encoder (motor option »C500« e.g. SM 87.2.18M6 C500).
The SERS/WSERS must be ordered with option »E50/C« (e.g. WSERS 04.80 V01 E50/C).
      Closed Loop
      A stepper motor system with Closed Loop control combines the advantages of stepper motors
high response in case of short positioning movements
no hunting at stand still
no Gain Tuning necessary
small load angle
      with the advantage of Servo Motors (motor does not loose its synchronism – no more loosing steps).
      By using Closed Loop control the stepper motor can be operated always with its maximum torque.
The result is a high dynamical operation (with maximum motor acceleration).
When sizing a stepper motor system the usually planned torque safety can be reduced or maybe even
skipped. For many applications therefore a smaller motor can be selected.
Stepper motor in open loop compared with stepper motor in Closed Loop control

As long as the load angle is <1,8°, the stepper
motor will be operated in open loop mode.
If the load angle is greater or equal to 1,8° (in
open loop the motor now would stall) the
stepper motor will be operated automatically
in »closed loop mode«.

Stepper motor in Closed Loop control compared with a servomotor

  The stepper motor follows its position command values immediately (left picture).
But a SERVO motor can only start and stop with a delay / settling time, due to its system, where the position needs to be monitored continously (right picture).

  At motor stand still the stepper motor completely stands still (left picture).
But a SERVO motor is slightly moving forward an backward around his stand still position (what is called hunting – right picture).

        position control SERS/WSERS and SERS Programmer 2 – single data sheet (641 KByte)
        stepping motor controls catalogue 2015 – catalogue (1838 KByte)
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