Lenze 931E/K Small Drives Control - Manual (Page 23)

Commissioning
Speed control
Functions available
5
l
23 SW−HB 13.0002−EN 4.1
current control circuit and a higher−level speed control circuit. The controllers are designed
as PI controllers. Using the setpoint selectors, you can select setpoints from different
sources for the corresponding controllers. See the chapter "Setpoint selection via setpoint
selectors". (
¶ 27)
The system principles are described in the block diagram on the next page.
With rotor−oriented control, two phase currents and the rotor position will be measured.
Using the Clark transformation, the phase currents will be converted into an imaginary and
a real part first and then transformed into the rotor coordinates by using the Park
transformation. Using PI controllers, the rotor currents can thus be converted into
corresponding rotor voltages and again be inversely transformed into the stator system.
The driver signal generation uses a symmetrical pulse−width modulation for the power
stage in sine commutation with the 3rd harmonic wave.
An integrator monitors the current 2 −time−integral of the controller. If the maximum value
(maximum current for 2 sec) is exceeded, a warning will be sent and the current will be
limited to the rated current.
With speed control, a setpoint speed will be selected. The 931E/K servo positioning
controller uses the encoder evaluation to determine the current actual speed n_act.