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Parameter Independent Encoderless Control of Servo Drives without Additional Hardware Components
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| Author(s) |
Ralph Kennel, Oscar Cabral Ferreira, Pawel Szczupak |
| Abstract |
A lot of methods for sensorless drive control have
been published last years for synchronous and asynchronous
machines. One of the approaches uses high frequency carrier
injection for position control. The injected high frequency signal
is controlled to remain in alignment with the saliency produced
by the saturation of the main flux. Due to the fact that it does
not use the fundamental machine model which fails at standstill
of the magnetic field it is possible to control the drive even at
zero speed. In spite of this obvious advantage industry does not
apply sensorless control in their products. This is due to the
dependency of many published methods on physical parameters
of the machine. The high frequency carrier injection method
presented in this paper does not need to have exact machine
parameters and it can be used for machines where there is only
a very small rotor anisotropy like in Surface Mounted Permanent
Magnet Synchronous Machines (SMPMSM)[3].
Standard drives usually are supplied by a 6-pulse diode rectifier.
Due to new European Directives concerning the harmonic
content in the mains it is expected that the use of controlled
pulse-width modulated PWM rectifiers will be enforced in the
future [1]. Important advantage of this type of rectifiers is the
regeneration of the energy back to the grid. Another benefit
are low harmonics in comparison to diode rectifiers. Using one
of many control methods published so far it is also possible
to achieve almost unity power factor. However, in these methods
voltage sensors are necessary to synchronize PWM rectifiers with
the mains. Therefore they are not very popular in the industry
with respect to the cost and the lack of reliability. Recently
a control method was proposed which is based on a tracking
scheme. It does not need any voltage sensor on the ac-side of the
rectifier and it does not need to know accurate parameters of
the system.
This paper presents the control solution for a cheap, industry
friendly (no additional hardware and installation effort) drive
system. The phase tracking method for control of electrical
drive and PWM rectifier is described. Encouraging experimental
results are shown. |
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| Filename: | 059 |
| Filesize: | 570.5 KB |
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| Type |
Members Only |
| Date |
Last modified 2006-02-07 by System |
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