| Abstract: | In this thesis a sensorless field oriented control of permanent magnet synchronous machine for blower applications opearting in a wide range of speeds is presented. At low speeds of rotation, volume air flow through the blower is very small, therefore, blowers operate predominantly at higher speeds. Consequently, sensorless control issue of this work is focused on higher speeds and on field weakening control of the synchronous machine. Presented sensorless field oriented control is suitable for general industrial use. Due to its relative simplicity, it can also be used in low-cost industrial applications. The blower first starts up to a certain speed of rotation with the open speed control loop. At sufficient speed of rotation, the speed control loop is closed. The machine rotor position and the speed of rotation, is obtained by the PLL observer. One of the central parts of this thesis is the sensitivity analysis, given for two different PLL observer structures. Based on given analysis, the PLL observer structure, which is suitable for the use in a wide range of speeds, is selected. A wide range of speed of rotation is achieved with the new field weakening control structure of the permanent magnet synchronous machine, where all the available dc-bus voltage of inverter is exploited. Further, stability analysis of the new filed weakening control structure is made. Based on the performed analysis guidelines for the proper choice of parameters for the field weakening control structure are given, so that the stable operation of the machine is assured. The results of simulations and experiments are compared for the new and allready
existing field weakening control structure. The comparison shows, that when the new field weakening control structure is applied, the transition of the machine between the constant torque and field weakening region of operation is smoother. At the end, the proposed sensorless field oriented control using the PLL observer and the new field weakening control structure is verified experimentally, on the blower, operating in a broad range of speeds. |
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