This paper presents a simple and efficient technique for power factor correction (PFC) and total harmonic distortion (THD) minimization of a SEPIC converter fed from AC supply. The performance of the SEPIC converter is studied through the power simulation program (PSIM) under different supply conditions with different loads. The obtained results have shown a very simple technique to obtain sinusoidal supply current at unity power factor with the different loads. Also, the proposed control technique can give sinusoidal supply current whatever the exciting supply contains harmonics or not

Ezzat, M.

English

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Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  118  Sinusoidal Reference Technique for Power Factor Correction of a SEPIC Converter Fed from AC Supply Ezzat, M.   (Corresponding author) Faculty of Engineering, Menoufiya University Shebin El_Kom, Menoufiya, Egypt E-mail: en.ezzat@yahoo.com  The research is supported by Electrical Engineering Department, Faculty of Engineering, Menoufiya University, Egypt.  Abstract This paper presents a simple and efficient technique for power factor correction (PFC) and total harmonic distortion (THD) minimization of a SEPIC converter fed from AC supply. The performance of the SEPIC converter is studied through the power simulation program (PSIM) under different supply conditions with different loads. The obtained results have shown a very simple technique to obtain sinusoidal supply current at unity power factor with the different loads. Also, the proposed control technique can give sinusoidal supply current whatever the exciting supply contains harmonics or not.  Keywords: PFC, SEPIC, Simulation, THD minimization  1. Introduction Single-ended primary-inductor converter (SEPIC) is a type of DC-DC converter allowing the electrical potential (voltage) at its output to be greater than, less than, or equal to that at its input; the output of the SEPIC is controlled by the duty cycle of the control transistor. A SEPIC is similar to a traditional buck-boost converter, but has advantages of having non-inverted output (the output voltage is of the same polarity as the input voltage), the isolation between its input and output (provided by a capacitor in series), and true shutdown mode. On the other hand, power factor correction converters are extensively used in the industrial life. These converters aim at increasing the power factor and decreasing the total harmonic distortion of the supply current. Power factor correction and minimization of total harmonic distortion find great interest from researchers [1-6]. The international standards such IEC 61000-3-2 [7] restrict the maximum allowable total harmonic distortion for the current drained from the electric system. This paper presents a simple control technique for PFC and THD minimization of a SEPIC converter fed from AC source to show the effectiveness of the proposed control strategy.  2. Proposed Control Technique Fig. 1 shows a circuit diagram of the proposed control technique. The main idea of the control technique is to generate a reference sinusoidal supply current from the error signal which results from comparing the reference and the actual output voltage signal. The reference sinusoidal supply current must be synchronized with the supply voltage for the purpose of PFC. The THD will be also minimized as a result of using a reference sinusoidal signal for supply current. The important notice here, the supply current is expected to be sinusoidal if the supply voltage is sinusoidal or contains harmonics.       Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  119                Figure 1. Circuit Diagram of the Proposed Control Technique  3. Performance of SEPIC with The Control Technique Fig. 2 shows the circuit diagram of the well known SEPIC converter fed from an AC supply via a single-phase bridge rectifier. The proposed control technique which described in the previous section has been applied to the converter circuit at two different load types (e.g. Resistive & Resistive-Inductive Loads). Also, it has been applied under different supply conditions.          Figure 2. SEPIC Converter Fed from AC Source  4. Simulation Results with Resistive-Inductive (RL) Load This section presents the simulation results of the SEPIC converter under the proposed control technique with RL load at two different cases of the AC supply voltage. Figs. 3a to 3d show the AC supply voltage, output voltage, supply current and the fast Fourier transform (FFT) of the supply current for a sinusoidal AC input voltage.             Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  120  Figure 3a. Sinusoidal AC Supply Voltage             Figure 3b. Output Voltage at a Reference Signal of 200 Volt and RL-Load              Figure 3c. Reference and Measured Supply Current at a Reference Signal of 200 Volt and RL-Load              Figure 3d. FFT of Supply Current at a Reference Signal of 200 Volt and RL-Load  From the above figures, it can be seen that the circuit power factor is approximately equal to unity and the supply current is approximately sinusoidal which means a minimized THD. Figs. 4a to 4d show the    Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  121  AC supply voltage, output voltage, supply current and the fast Fourier transform (FFT) of the supply current for an AC supply voltage contains harmonics.             Figure 4a. AC Supply Voltage contains Harmonics              Figure 4b. Output Voltage at a Reference Signal of 100 Volt, Distorted Supply and RL-Load              Figure 4c. Reference and Measured Supply Current at a Reference Signal of 100 Volt, Distorted Supply and RL-Load     Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  122               Figure 4d. FFT of Supply Current at a Reference Signal of 100 Volt, Distorted Supply and RL-Load  Also, the above figures illustrates that the THD in supply current is very small whatever the AC supply contains harmonics or not which support the proposed control technique.  5. Simulation Results with Resistive (R) Load This section presents the simulation results of the SEPIC converter under the proposed control technique with R load when the AC supply voltage is distorted. Figs. 5a to 5d show the AC supply voltage, output voltage, supply current and the fast Fourier transform (FFT) of the supply current for a sinusoidal AC input voltage.              Figure 5a. AC Supply Voltage contains Harmonics             Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  123    Figure 5b. Output Voltage at a Reference Signal of 150 Volt and R-Load             Figure 5c. Reference and Measured Supply Current at a Reference Signal of 150 Volt and R-Load              Figure 5d. FFT of Supply Current at a Reference Signal of 150 Volt and R-Load  6. Conclusion A simple control technique for power factor correction and total harmonic distortion minimization of a SEPIC converter fed from AC supply has been presented. The performance of the SEPIC converter under the proposed control technique has been also presented at different conditions. The obtained results have shown a simple and efficient control technique that can be used for the proposed purpose. References [1] Azazi, H. Z.  et al (2011), " DSP-Based Control of Boost PFC AC-DC Converters Using Predictive Control", JEE Journal.  [2] Roggia, L.  et al (2009), " Digital Control System Applied to a PFC Boost Converter Operating in Mixed Conduction Mode", Proc. IEEE App. of Power Electronics, 698-704. [3] Rao, V. M., Jain, K. A., Reddy, K. K. & Behal, A.  (2008), " Power Factor Correction without Current Sensor Based on Digital Current Rebuilding", IEEE Transactions on Power Electronics 55, 67-78.  [4] Wanfeng Zhang, Guang Feng, Yan-Fei Liu & Bin Wu (2006), " New Digital Control Method for Power Factor Correction", IEEE Transactions on Industrial Electronics 53, 987-990.  [5] Chen, J.  et al (2003), " Predictive Digital Current Programmed Control", IEEE Transactions on   Innovative Systems Design and Engineering    www.iiste.org ISSN 2222-1727 (Paper) ISSN 2222-2871 (Online) Vol 2, No 4, 2011  124  Power Electronics 18, 411-419.  [6] Buso, S. & Mattavelli, P.  (1998), "Simple Digital Control Improving Dynamic Performance of Power Factor Pre regulators", IEEE Transactions on Power Electronics 13, 814-823.  [7] Compliance Testing to the IEC 1000-3-2 (EN 61000-3-2) and IEC 1000-3-3 (EN 61000-3-3) Standards and Application Note 1273, Hewlett Packard Co. Dec. 1995. Appendix Parameters of SEPIC Converter: Inductance (L1 & L2) = 1 mH. Capacitance (C1) = 10 micro Farad. Capacitance (C2) = 500 micro Farad. Load Resistance = 40 Ohm. Load Inductance = 0.1 H.   This academic article was published by The International Institute for Science, Technology and Education (IISTE).  The IISTE is a pioneer in the Open Access Publishing service based in the U.S. and Europe.  The aim of the institute is Accelerating Global Knowledge Sharing.  More information about the publisher can be found in the IISTE’s homepage:  http://www.iiste.org  The IISTE is currently hosting more than 30 peer-reviewed academic journals and collaborating with academic institutions around the world.   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Sinusoidal Reference Technique for Power Factor Correction of a SEPIC Converter Fed from AC Supply

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Sinusoidal Reference Technique for Power Factor Correction of a SEPIC Converter Fed from AC Supply

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