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W. Mistelberger:
"Sensorlose Positionsregelung einer PSM";
Supervisor: E. Robeischl, M. Schrödl; E372, 2000.

This diploma-thesis deals with the realization of a position-sensorless positioning system with a permanent magnet synchronous motor (PMSM). The term "sensorless" denotes, that there is no mechanical sensor for detection of the rotor position or for the detection of the linear position of the system. Due to improvement on magnet materials the PMSM has an increasing importance for drives in the lower and medium power range.
Since the PMSM requires no commutator, the effort of maintenance is less in relation to the d.c. motor. The control structure of the field oriented control of the PMSM is also easy to handle. It is only necessary to detect the direction of the main flux linkage to receive the actual rotor position.
The efficiency of the PMSM is very high since it has almost no losses in the rotor. The inverter-system, which is based on a voltage source inverter is designed for a nominal motorpower up to 2 kW and includes all components that are needed for a sensorless control of the system. Thus only two cables are required; one to connect the system to the mains, and one to link the inverter with the motor.
The algorithms for the position-sensorless position control, the position detection and the field oriented control are implemented in a digital signal processor. It is only required to measure the DC-link current of the voltage source inverter. All other signals like angular rotor speedand position are derived from the measured DC-link current. For the sensorless position detection two models are used. The INFORM-Model, which was developed at the institute of electrical drives and machines, is used for low rotor velocities down to standstill. For higher velocities an emf-based model for rotor-position estimation is used.
This thesis should especially explain the relation between the used mathematical models and the software-implementation. Other main fields are the control of the position and an improved measuring-sequence for the INFORM-model. Finally the results and conclusions are presented. The method of sensorless position control has a wide field of applications, especially in the medium range of the positioning accuracy.