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Encoderless Control of Industrial Servo Drives
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| Author(s) |
Oscar Cabral Ferreira, Ralph Kennel |
| Abstract |
High resolution optical encoders are used in industrial
servo drives with position and/or speed control for
providing the respective feedback signals. In applications
with lower accuracy requirements resolvers are used as
feedback sensors with respect to lower cost. As a resolver is
nothing else than an electrical AC machine of special design,
there is the basic idea to operate the servo motor itself like a
resolver –in parallel to its original drive operation, of
course. High frequency resolver signals are injected to the
servo motor without disturbing its original purpose (i. e. the
production of torque). The reaction of the servo motor on
the high frequency signals can be detected by the current
sensors, which are available with respect to the current
control loop anyway.
A lot of schemes and concepts for encoderless AC drive
control providing good operation during standstill are already
published. Acceptance by industry, however, is not
very extended. The main reasons for hesitations in industry
are:
• additional processing performance being necessary
for the controller or signal processor
• additional sensors or hardware
• parameters to be adjusted for encoderless control
The concept for encoderless control presented in this paper
has no restrictions with respect to a minimal speed or
frequency. Furthermore it is possible to implement it in
industrial servo drives without additional hardware requirements
and without parameter adjustments. |
| Download |
| Filename: | T16-605.pdf |
| Filesize: | 234.9 KB |
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| Type |
Members Only |
| Date |
Last modified 2007-03-08 by System |
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