Design and implementation of robust converter circuits with unity power factor

Modern electronic circuits and equipment don?t behave exactly as a linear load for AC network. Today, one or more switching converter is used in most electronic systems and these converters attract non-sinusoidal current from the network. This current contains harmonics causing distortions at voltage and current. From these reasons, other equipments connected to network may be affected from these distortions and problems can occur at networks. Therefore, using of thicker wires is being a necessity and the availability and efficiency of network can reduce. To overcome all these problems in the network as an acceptable level of harmonic distortion is required to withdraw and for this purpose and method of power factor correction (PFC) circuits have been developed.In this thesis, DC link voltage of two-level inverter is provided over a PFC circuit in order to correct the input current of these inverter systems. Bridge rectifiers used for DC link voltage draw input current from network with 70-80% THD levels. It is aimed to eliminate this situation that a boost converter circuit is connected to the output of bridge rectifier and operated to achieve high PF values and obtain a variable regulated DC voltage. There are two controllers is used for voltage and current at PFC algorithm. When the converter circuit is operated for PFC operation and generating variable DC voltage, a robust controller is required to overcome changes in input-output voltage, load and input current. In this study, the fast and robust Sliding Mode Controller (SMC) for current is used. This control method has chattering problem because of variable structure of algorithm. Because of this situation, Fuzzy Control is adapted SMC to increase the stability and to cope with the chattering problem caused sliding mode or variable structure control algorithm. Obtained control algorithm is named Sliding Mode Fuzzy Control (SMFC). The robustness of the designed control structure used as a current controller is tested for changings of input voltage, output voltage and load. This PFC algorithm is implemented by using DS1103 Digital Signal Processor. The algorithm prepared with MATLAB/Simulink and Simpower is converter to real time codes by help of MATLAB/Real Time Workshop and dSPACE Real Time Interface. After obtaining 0.99 PF values, the output voltage of DC-DC converter is used as a DC link voltage of two-level inverter. Owing to the advantages of Space Vector Pulse Width Modulation (SVPWM) is chosen for the system which is designed for driving asynchronous machine. This algorithm is implemented by using dsPIC30F4011 microcontroller.Performances of the used algorithms, designed circuits and all of the system put forth for different operating conditions. The achievement of SMFC algorithm at PFC is presented by using the obtained results with graphics and harmonic improvement is presented with tables and graphics by comparing structure without PFC. As a result, 0.99 PF value, robust current control, variable DC link voltage and low THD values for current of asynchronous machine are provided by the designed and implemented system.