DSP Based Power Factor Improvement using Single Phase Active Power Filter A review

This project presents a technique for single phase power factor correction of non-linear loads employing an active power filter. The current control strategy is the same used in the boost pre-regulator, which is the average current mode technique. The project will focus on the design methodology and the analysis of the control strategy which allows the compensation of harmonics and phase displacement of the input current, for single and multiple non-linear and linear loads. Experimental results of an active filter controlling a 200W to 1KW rectifier with a capacitive filter, an 8OOW AC chopper and a 58OW multiple load, which consists of a rectifier with a capacitive filter and an AC chopper, are presented. In the last years the use of electronic equipment has been increasing rapidly. This equipment draws The current from the AC mains has harmonic components, which leads to low power factor, low efficiency, interference in some instruments and communication equipment by the EMI, overtaxed electrical-distribution systems, overheated transformers and electromagnetic fields. However, passive filters have many disadvantages, such as large size, resonance, and fixed compensation characteristics. Therefore, it does not provide a complete solution. The most usual single phase non-linear load is the frontend rectifier followed by a bulk capacitor, which draws current from the input during its charging. The boost pre-regulator is used to reduce the harmonic contents and improves the power factor. The current control loop consists in the average current mode technique. The boost pre-regulator has some disadvantage because it cannot be used in equipment already in service, and it is applied only to one kind of non-linear load which is the front end rectifier followed by a bulk capacitor. A very interesting solution is the use of a single-phase active power filter, which is connected in parallel with then on-linear loads. The active power filters concept uses in power electronics to produce harmonic components which cancel the harmonic components from the non-linear loads. It can limit harmonics to acceptable levels and can adapt itself in case of harmonic component alteration or even changes in then on-linear loads types. Usually the technique used to control the single-phase active filter senses the non-linear load current and calculates its harmonics. This project will focus on the design and the control strategy for a shunt single-phase active power filter.