Published in IET Power Electronics Received on 13th September 2011 Revised on 4th November 2011 doi: 10.1049/iet-pel.2011.0348 ISSN 1755-4535 Average sliding control method applied on power factor correction converter for decreasing input current total harmonic distortion using digital signal processor A. Karaarslan 1 I. Iskender 2 1 Department of Industrial Technology Education, Gazi University, Ankara, Turkey 2 Department of Electrical Electronics Engineering, Gazi University, Ankara, Turkey E-mail: akaraarslan@gazi.edu.tr Abstract: This study presents an average sliding control (ASC) method to be used in power factor correction (PFC) circuits to decrease the total harmonic distortion (THD) of the input current by eliminating the input current harmonics. The ASC algorithm is adapted to TMS320F2812 digital signal processor (DSP) owing to its well-known properties, such as robustness, stability and good regulation in a wide range of operating conditions. The control approach is operated in continuous conduction mode. In this approach, a sinusoidal signal is generated by the DSP and is used as reference in controlling the converter switch to obtain a sinusoidal input current based on zero-crossing points of input voltage. The feed-forward is also used in the control algorithm using maximum value of the input voltage. The implementation of feed-forward improves the converter’s performance to obtain a near-unity PFC with a lower input current THD. The converter used in the simulation and experimental studies is a bridgeless converter. The conduction losses of the switches of this converter are lower compared with the similar PFC converters. The experiments performed in the laboratory for different cases of operation verify the theoretical and simulation studies. The experimental results are satisfied by IEC 61000-3-2 current harmonic standard. 1 Introduction In recent years, the number and power level of power electronic converters in industrial and household applications have significantly increased. These applications perform AC to DC conversion and include bridge rectifiers and large DC-link capacitors. Such rectifiers produce a large amount of harmonics in the AC line currents, leading to poor input effective power factor (PF) and causing source voltage disturbances [1, 2]. Therefore improving the PF and reducing the line current harmonics of the rectifiers are important. For these purpose many solutions and topologies have been introduced related to power factor correction (PFC) circuits and their applications [3–6]. The main task of the controller in unity PF converters must be to guarantee a sinusoidal input current in phase with the line voltage and maintain the output voltage around a specific average value with low ripple. It is desirable to achieve a fast dynamic response of the output voltage without causing input current distortion. Generally, the improvement in the PF and the line current harmonics of the rectifiers are accomplished using digital PFC controllers. The controllers based on digital signal processor (DSP) have many advantages over analogue controllers, including programmability, adaptability, less susceptibility to environmental variations, no temperature and aging effect, more immunity to the input voltage distortion, and so on [7–10]. It also reduces the size of the power circuit by containing the complexity of control system within the software. This paper proposes a control solution enabling both the control of the input currents and the regulation of the output voltage. For these purposes the average sliding control (ASC) method is implemented to the bridgeless PFC converter and a proper sliding surface is chosen to allow robust near-unity PF operation [11–14]. Another important aspect of this study is that the AC input current is controlled to trace the pure sinusoidal signal generated by the DSP based on the zero cross-point detection of the input voltage. The generated AC signal is in phase with the input voltage and has the same frequency. In conventional PFC circuits the input current is controlled to trace the input voltage which is not always a sinusoidal wave and sometimes includes serious distortions. The simulation and experimental studies show that the proposed strategy works well and unity PF can be achieved with the load and line frequency variations. This study is in agreement with IEC 61000-3-2 current harmonic standard [15] and meets the requirements of the electrical quality standards concerning the input current entering low-power equipments. In this paper, the principle of the PFC converter is discussed in Section 2. The control strategy and the proposed algorithms for PFC implementation are presented in Section 3. The simulation and experimental results are studied in Sections 4 and 5, respectively. The conclusion is given in the last section. IET Power Electron., 2012, Vol. 5, Iss. 5, pp. 617–626 617 doi: 10.1049/iet-pel.2011.0348 & The Institution of Engineering and Technology 2012 www.ietdl.org