Command
processing
The analog input goes through a number of signal processing
steps before becoming the actual motor velocity command
VelCmd
as shown by Figure 2.
1. Analog input differential amplifier with 1200 Hz low pass
filter.
2. High resolution A/D sampled at the velocity loop update rate
and added to the
ADOffset
parameter.
3.
ADF0
adjustable low pass filter to become the
AnalogIn
variable.
4. Range clamped by the
VelLmtHi, VelLmtLo
parameters.
Velocity loop
compensation
The actual velocity command (
VelCmd
) is then combined with
the measured shaft velocity (
VelFB
) and processed by the
velocity loop compensation to create the motor torque current
command (
ICmd
). The detailed signal processing steps to create
ICmd are listed below and shown in Figure 1.
1.
VelErr
set equal to (
VelCmdA - VelFB
)
2. The anti-resonance second order velocity loop compensation
block controlled by the
ARF0, ARF1, ARZ0,
and
ARZ1
parameters to become the
FVelErr
variable.
3. The proportional and integral velocity loop compensation
block controlled by the
KVP
and
KVI
parameters
respectively.
4. And finally through the
IlmtPlus
and
IlmtMinus
current command clamp to become the
ICmd
motor torque
current command variable.
For more information on tuning the velocity loop see Chapter 4
Servo Loop Parameters.
A - 4
MA950
