Kollmorgen BDS5, Инструкция по установке и настройке

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C
HAPTER
3 - O
PERATION
BDS5
3-4
range for KC is between 175 and 225. This
adjustment must be repeated when either the
motor or the amplifier is changed out.
4. Restore PL. Type:
PL ON
This completes the initial check-out.
3.3 SYSTEM COMPENSATION
Feedback systems (like a motor controller) require
tuning to attain high performance. Tuning is the
process whereby the position and velocity loop gains
are set, attempting to optimize the performance of a
system (a BDS5 and a motor connected to a load) to a
three-part criterion:
Table 3.1. Tuning Criterion
Noise Susceptibility
Response
Stability
Tuning is normally a laborious procedure requiring
an experienced person. However, the BDS5 provides
many tools to aid tuning, making it a much simpler
process than it has been in the past.
In a broad sense, the performance of a system is
characterized by its noise susceptibility, response, and
stability. These quantities tend to be mutually
exclusive. The system designer must decide what
noise susceptibility (in the form of a "busy" motor) is
acceptable.
"Busyness" is random activity in the motor and can
often be felt on the motor shaft. Busyness in a motor
should not be confused with PWM noise. PWM
noise is high pitched, relatively constant noise and
cannot be felt on the motor shaft.
Response is a measure of the system's quickness.
Response can also be characterized by bandwidth and
by rise time in response to a step command.
Normally, designers want high bandwidth, though
sometimes the response is purposely degraded to
reduce stress on mechanical components. This is
called
detuning . Typical velocity loop bandwidths
range from 20 to 60 Hz. Typical position loop
bandwidths range from 0.1 to 0.2 times the velocity
loop bandwidth.
Stability measures how controlled the system is.
Stability can be measured with damping ratio or with
overshoot in response to a step command. A
discussion of different levels of stability follows.
3.3.1 Critical Damping
Generally, the most desirable amount of damping is
Critical Damping. Critically damped systems
respond as fast as possible with little or no overshoot.
In Figure 3.1, the graph shows the response of a
BDS5 TACH signal (on Connector C2, Pin 2) to a
square wave input when the system is critically
damped.
Figure 3.1. Critical Damping
3.3.2 Underdamping
Sometimes the system is tuned for critical damping
and the system is still too slow. In these cases, you
may be willing to accept less than critical damping.
For applications that can work properly with a
slightly underdamped system, you may reduce the
stability to improve the response. The graph in
Figure 3.2 shows a BDS5 slightly underdamped.