단상 유도전동기의 저전력 응용을 위한 저가격 벡터제어 시스템
Low-Cost Vector Control System for the Low-Power Application of the Single Phase Induction Motor
단상 유도전동기 저전력 저가격 벡터제어 가변속 제어;
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This thesis investigates the speed sensorless vector control of a single-phase induction motor drive to implement low-cost systems for low-power applications. The static power converter side is implemented using a single-phase rectifier cascaded with a four-switch inverter. The vector control is based upon field orientation concepts that have been adapted for this type of machine. The speed estimation is implemented only one current sensor. In the case of the capacitor-start induction motor, it take advantage of winding usage if the auxiliary winding used only on start-up is utilized at steady state operation.; i.e. considering auxiliary winding to a phase of motor, single-phase induction motor is able to be considered two-phase unbalance induction motor. Therefore it would be applicable of vector control technique for three-phase machine by its modeling and analytical study. The single-phase induction motor utilizing auxiliary winding has a drawback of complicated mathematical modeling due to asymmetry of windings. For application of existing vector control principle for three-phase machine, its stator current has to be separated into components of flux and torque with 90° phase shift. Single-phase induction motor is physically designed to keep its 90° phase shift, but its phase shift is not possible to keep with 90° due to electrical asymmetry or unbalance of each parameters of main and auxiliary windings, By this reasons, it is difficult to apply existing vector control technique for three-phase machine to single-phase machine without any modification. The vector control system for three-phase induction machine is equipped with full bridge inverter and develop axis transformation on the assumption that each three-phase winding of machine is electrically balanced with 120° phase shift, the same turn-ratio and resistance. This theses, for the realization of low-cost vector control system of single-phase unbalanced induction motor, implements a single-phase half-bridge inverter system cascaded with double voltaged rectifier circuit, and investigates and proposes the speed sensorless vector control method by measuring the phase current using only one current sensor. And the modeling, simulation and experimental results of 800W single-phase induction motor and driver system are performed to verify the proposed control method. This thesis configure to following. Chapter 1 describe the need of study and subject about vector control method of single-phase induction motor. Chapter 2 investigate the usefulness of the applications of variable speed control of single-phase induction motors. Chapter 3 introduce variable speed control methods of the single-phase induction motor and control advantages of using both main and auxiliary winding, like as a balanced two-phase machine. Chapter 4 propose the simplified vector control model applicable for low-cost microcontroller and the low-cost speed sensorless vector control method for low-power applications. Chapter 5 introduce the space vector modulation method for single-phase induction motor by half-bridge inverter. Chapter 6 show the configuration of experimental system, the specification and the experimental results. Finally, chapter 7 descirbe the conclusions.