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Automatic Tolerance Band Tuning in Direct Torque Control


J. Kley

Semester/Bachelor Thesis, WS 06/07

The problem when using Direct Torque Control (DTC) as control strategy on drives is, that with constant tolerance band widths for torque and flux error, the switching frequency becomes a function of the modulation index (motor speed). Furthermore, switching frequency depends on the induction machine type currently used. Up till now a manual and time-consuming tuning process lead to a standard configuration for the inverter’s tolerance band curves, which has been used for any type of induction machine. Now, an algorithm has been developed and implemented in Excel/Visual Basic, using DriveDebug’s DLLs as interface to the drive, which highly automates this tuning process. The auto-tuning tool runs an on-line tuning from a PC connected to the drive. The auto-tuning tool reads the tuning goals (desired inverter switching frequency and torque ratio) for various operating points (modulation indexes) as input and in less than one hour, the tolerance bands are configured without user interaction to meet the specified constraints on a real drive. Even tuning with load can be performed. Theoretically it is now possible to configure every drive’s tolerance band curves to the optimum, which allows a higher degree of utilization for the inverter and leads to a significant improvement of torque quality. With only slight adjustments, the developed algorithm should also be suitable for the tuning of synchronous drives and even other inverter models as for example five level inverters.

Supervisor ABB: P. Bohren
Supervisors ETH: A. Beccuti, Dr. S. Mariéthoz
Professor: Prof. Dr. M. Morari


Type of Publication:

(13)Semester/Bachelor Thesis

M. Morari

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% Autogenerated BibTeX entry
@PhdThesis { Xxx:2007:IFA_2740
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