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R. Kremsl:
"Entwurf, Aufbau und Inbetriebnahme eines zeitdiskreten Hardware-Stromreglers mit Zwischenkreismessung";
Betreuer/in(nen): E. Robeischl, M. Schrödl; E372, 2000.

This diploma theses deals with the development of a hardware-current-controller for sensorless control of PMSMs (permanent magnet synchronous motors).
The hardware-current-controller is a discrete-time controller, that means that the actual values of the phase-currents are detected and compared to the reference values in certain time intervals. Depending on the result of this comparison, the switches of the inverter will be set.
The detection of the actual values of the phase-currents is realized by measuring only the DC-link-current. Knowing the switching state of the inverter, it is possible to conclude on the phase-currents from the DC-link-current. The reference values of the phase-currents are calculated according to conventionally techniques by a digital signal-processor (DSP), and are then transfered to the hardware-current-controller by means of filtered PWM-outputs of the DSP.
Additionally a possibility to bypass the hardware-current-controller is realized for applying direct INFORM-sequences on the inverter.
The hardware-current-controller was built up on an own printed circuit board and integrated into an existing system at the Institute of Electrical Drives and Machines at the Technical University of Vienna.
Tests on the hardware-current-controller leaded to the following main advantages compared to a software-based current control used by the Institute of Electrical Drives and Machines until now:
· 30-times faster step response
· reduced sampling time due to the outsourcing of the current control from the DSP
· no phase current measurement needed.
Because of the control structure there are minimum deviations of the actual values from the reference values of the phase currents. These deviations are mainly defined by the inductance of the PMSM and cannot be reduced.