Manual MCD
+
A3 Overdrive Function
The MCD power stages can compensate the phase current decrease in the upper speed
range by the Overdrive function. Overdrive is independent of the motor type.
Overdrive is a dynamic boost function, which will be automatically switched on if this
makes sense in regard of the current shape:
Fig. 35: Phase currents with Overdrive
The stepper motor phase current decreases with increasing step frequency caused by the
counter-electromotive force of the motor.
The Overdrive function compensates the decrease of current and torque. The phase
current is increased by about 20 % in Overdrive function. The switching frequency based
on FS can be selected from 225 Hz to 225 kHz. This switching frequency is set to
1,000 Hz input control pulse by default. The switching-off frequency is 10 % lower than the
switching-on frequency for producing a hysteresis.
The stepper motor torque decreases by increasing of the rotation speed.
The Overdrive function works against the reducing of the torque at middle and high
rotation speeds.
The function Overdrive is activated on delivery and can be switched off in the ServiceBus
mode by ServiceBus-Comm
®
.
The parameterization is done by the ‚PH‘ instruction code.
MA 2102-A005 GB
48
