Sensorless Field Oriented Control of Three-Phase Induction Motor using Fuzzy PI Controller

Abstract

Due to enermous application of induction motor, it is must that the control mechanisms are invistigated through proper research. This thesis mains to investigate sensorless vector control of induction motor using Fuzzy Logic Controller. The purpose of using FLC is to guarantee fast response and improved dynamic performance of the drive system. The whole control is reinforced by a Rotor-Flux Model Reference Adaptive System (RF-MRAS) for rotor flux and speed estimation. Also, space vector modulation algorithm is proposed to provide fixed switching frequency, better DC bus utilization and reduce the total harmonic distortion in the inverter.The proposed method is simulated in MATLAB software. The robustness of the overall system is tested under load torque injection while running the simulation. The simulation result showed that the indirect FOC with proposed observer provides good performance dynamic characteristics for different operating modes.

The universal voltage source inverter is developed in the laboratory with TMS320F28069M Texas Instrument's launchpad. With the developed inveter, two different experimental setup are proposed for this project. Firstly, the closed-loop speed control algorithm is investigated for 3 hp, 4 pole cage induction motor in the laboratory coupled to induction generator connected to resistive load. The speed and current controller parameters are derived from simulation work. The experimental result showed equivalent behavior as the simulation work. The second experiment is proposed on controlling the 7 kW compressor motor for the commercial air conditioning system based in Electrical Engineering Laboratory; Naresuan University. In this method, the motor parameters were not available. For this reason, the open-loop control algorithm was implemeneted. This was implemented with two important aims. These are reducing energy consumption and to ensure thermal comfort to the occupant in the building. A variable speed compressor using voltage source inverter along with then fuzzy logic controller (FLC) is porposed. FLC was developed to imitate the performance of human expert operators by encoding their knowledge in the form of linguistic rules. The Fluke Data Logger is used to monitor electrical componenet of the system. The room temperature, outside atmospheric temperature and coolant pressure are also monitored throughout the measurement period. In the analysis; coefficient of performance (COP), energy consumption, THD, power factor and energy saving are calculated. from this measuremnt, the result showed a energy saving of 1.42 kWh for 6 hours measurement period. It also showed a reduced THD, improved power factor in inverter-fed operation compared to the normal operation. This can have tremendous cost saving to the medium and large energy user by reducing the demand charge. Moreover, reduced THD and improved power factor have advanatges to the power grid operator and also to the interconnected system.

-