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Decentralized Control and Estimation for Common DC Bus Traction Systems


N. Le Clair

Master Thesis, HS14 (10340)

Currently in electric traction systems, the power is fed from the line to each of the motors through a line converter and motor converter. To gain effi- ciency and reliability, a modularity concept can be implemented to achieve distributed tractive effort; this requires the line converters that are distributed along the traction system, to feed one common DC bus system which provides power for all the motors and auxiliary components. Controlling the power on the DC bus via the distributed converters while achieving balanced load sharing, presents several control challenges.

In this thesis, centralized and alternative decentralized control strategies are proposed and compared to the benchmark case of droop control. Because of the offset in the voltage from the nominal value, a property intrinsic to droop control, this method leaves room for improvement.

A particular set-up was developed using decentralized state observers and state feedback controllers. In order to eliminate the need for communication of the exact control signals applied by each of the modules, the observers use an estimate of these control signals in order to estimate the global state. Necessary conditions for existence of such control methods and closed-loop stability conditions are derived. The system being investigated consists of two modules, or wagons, of the traction system. The main results are extended to a higher number of modules.

Supervisors: Silva Mastellone (ABB Corporate Research), Roy Smith


Type of Publication:

(12)Diploma/Master Thesis

R. S. Smith

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% Autogenerated BibTeX entry
@PhdThesis { Xxx:2015:IFA_5172
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