Field Oriented Control of AC Drives

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Dr. Stumpf Péter Pál
Department of Automation and Applied Informatics

Converter-fed adjustable speed electric drives play an important role in up-to-date high-performance digitally controlled engineering systems, from machine tooling via industry robotics through the utilization of renewable energies, as they enable the efficient conversion of electric power to mechanical power and vice versa.

The quality and reliability of the electric drives highly depends on the applied control algorithm. The aim of my final project is to study, implement and realize one of the most widely applied closed loop methods, Field Oriented Control (FOC) to a permanent magnet synchronous machine. The principal aim of the FOC is to control independently the flux and torque in an asynchronous/synchronous electric machine, in a similar way to the control of separately excited DC machine.

After a theoretical overview of synchronous motors and the field oriented control, my final project will demonstrate the steps of realization both in simulation and laboratory environment. The simulations were run in Matlab/Simulink environment. For the laboratory experiments I used a DSP card, capable of motor control and a low-voltage three phase inverter.

The big disadvantage of field oriented control is that the exact position and speed of the rotor is needed in order for it to function properly, therefore encoder or Hall-sensors are needed. In order to avoid the use of mechanical or optical sensors many so-called sensorless techniques have been developed, where the position and speed is determined through calculations. In my final project I will demonstrate a Kalman filter based technique, together with its simulation.


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