16.1.4 Tuning Speed PID Control
The following tuning guidelines are relevant when using
one of the flux motor control principles in applications
where the load is inertial (with a low amount of friction).
The value of
parameter 30-83 Speed PID Proportional Gain
depends the combined inertia of the motor and load. The
selected bandwidth can be calculated using the following
formula:
Par . 7 − 02 =
Total inertia kgm
2
x par . 1 − 25
Par . 1 − 20 x 9550
x Bandwidth rad/s
NOTICE
Parameter 1-20 Motor Power [kW]
is the motor power in
kilowatts. For example, enter ‘4’ kW instead of ‘4000’ W
in the formula.
A practical value for the bandwidth is 20 rad/s. Check the
result of the
parameter 30-83 Speed PID Proportional Gain
calculation against the following formula. This function is
not required if using high-resolution feedback such as a
SinCos feedback.
Par . 7 − 02
MAX
= 0 . 01 x 4 x Encoder Resolution x Par . 7 − 06
2 x π
x Max torque ripple %
A good starting value for
parameter 7-06 Speed PID Lowpass
Filter Time
is 5 ms. A lower encoder resolution calls for a
higher filter value. Typically, a maximum torque ripple of
3% is acceptable. For incremental encoders, the encoder
resolution is found in either
parameter 5-70 Term 32/33
Pulses Per Revolution
(24 V HTL on standard drive) or
parameter 17-11 Resolution (PPR)
(5 V TTL on VLT
®
Encoder
Input MCB102 option).
Generally, the encoder resolution and the feedback filter
time set the practical maximum limit of
parameter 30-83 Speed PID Proportional Gain
, but other
factors in the application can limit the
parameter 30-83 Speed PID Proportional Gain
to a lower
value.
To minimize the overshoot,
parameter 7-03 Speed PID
Integral Time
could be set to approximately 2.5 s. Time
varies with the application.
Set the
parameter 7-04 Speed PID Differentiation Time
to 0
until everything else is tuned. If necessary, finish the
tuning by adjusting this setting in small increments.
16.2 Process PID Controls
The process PID control can be used to control application
parameters that can be measured by different sensors
(pressure, temperature, and flow) and be affected by the
connected motor via a pump or fan.
shows the control configurations where the
process control is possible. Tune the speed control PID
parameters when a flux vector motor control principle is
used. To see where the speed control is active, refer to
chapter 14.3.1 Control Structure in VVC
Parameter 1-00 Conf
iguration Mode
Parameter 1-01 Motor Control Principle
U/f
VVC
+
Flux
sensorless
Flux with
encoder
feedback
[3] Process
–
Process
Process &
speed
Process &
speed
Table 16.4 Process Control Configurations
NOTICE
The process control PID works under the default
parameter setting, but tuning the parameters is highly
recommended to optimize the application control
performance. The 2 flux motor control principles depend
on proper speed control PID tuning to yield their full
potential. The speed control PID tuning occurs before
tuning the process control PID.
PID Controls
VLT
®
Parallel Drive Modules
146
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MG37N102
16
16
Summary of Contents for VLT 380-500 V
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