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T. Wolbank, P. Macheiner:
"Current controller with single dc-link current measurement for inverter-fed ac machines based on an improved observer-structure' IEEE Transactions on Power Electronics";
IEEE Transactions on Power Electronics, 19 (2004), 6; 1562 - 1567.

In modern industrial applications even low cost drives have excellent dynamic behavior which is achieved by field oriented control combined with high dynamic current regulation. Usually at least two phase current sensors are necessary to realize such an operation. In this paper a new current control scheme is presented, which enables high dynamic control of AC machine line currents with improved accuracy by measuring only the current of the DC link. The controller is based on three individual and adaptive phase current observers, which guarantee very accurate phase current estimates even at low modulation indices. Thus operation is possible even at low speed without modifying the switching pattern of the controller and the necessary modification at zero speed can be clearly reduced. Different realizations of the proposed scheme are given and a comparison is made to previously published schemes which are also based on a single DC link current sensor. Measurements performed on an induction machine drive at different points of operation show the applicability of the proposed structure. It is shown that the long term accuracy is clearly increased and the maximum deviation of the observer estimate from the actual phase current is reduced when using the proposed scheme.

http://aleph.ub.tuwien.ac.at/F?base=tuw01&func=find-c&ccl_term=AC04967906