Development of a Light Emitting Diode Lighting System with Power Factor Correction for Domestic Applications

The incandescent and fluorescent lighting systems which have been the most prominent electrical lighting choice for over 150 years are gradually being replaced in most homes with Light Emitting Diode (LED) Lighting Systems. This is due to their relatively low power consumption and good luminous intensity. LED lighting systems have revolutionized energy – efficient lighting. The significant feature of LEDs is that the light is directional with very low lagging power factor (0.2 – 0.6) as opposed to incandescent bulbs which spread the light more spherically with high power factor almost approaching unity. New LED designs address the directional limitation by using diffuser lenses and reflectors to disperse the light more. Since LED lighting represents a green technology, the issue of high power factor becomes very important. Power factor, defined as the ratio of real power consumed by a load (expressed in Watts) to apparent power (expressed in Volt-amperes), is a figure that ranges from zero to unity, it indicates the degree of distortion and phase shift in the current waveform. The work reported here proposes LED lighting system equipped with power factor correction driving circuit fed with dc – dc converter circuit. The power factor correction function is achieved by using switching converters circuit that operate directly from a full-wave rectified DC bus on a passive valley fill (PVF) circuit operating in Discontinuous Inductor Current Mode (DICM) for Power Factor Correction (PFC). This converter is simple to control, easy to construct and attractive for low cost application for domestic lighting. The results obtained have shown a LED lighting system with a lagging power factor of 0.85 that is energy – efficient compared to its conventional counterpart in domestic lighting applications

A Low Power Single-stage LED Driver Operating between Discontinuous Conduction Mode and Critical Conduction Mode

A novel single-stage single-switch (S4) LED driver is proposed in this paper. The paper focuses on the operation principles of the power stage circuit with an operation switched between Critical Conduction Mode (CRM) and Discontinuous Conduction Mode (DCM), including steady state analysis, simulation and backed up by experimental results. The results verify that this proposed LED driver can obtain a high power factor (PF) and the dc output is relatively stable

Nonlinear Analysis and Control of Interleaved Boost Converter Using Real-Time Cycle to Cycle Variable Slope Compensation

Switched-mode power converters are inherently nonlinear and piecewise smooth systems that may exhibit a series of undesirable operations that can greatly reduce the converter's efficiency and lifetime. This paper presents a nonlinear analysis technique to investigate the influence of system parameters on the stability of interleaved boost converters. In this approach, Monodromy matrix that contains all the comprehensive information of converter parameters and control loop can be employed to fully reveal and understand the inherent nonlinear dynamics of interleaved boost converters, including the interaction effect of switching operation. Thereby not only the boundary conditions but also the relationship between stability margin and the parameters given can be intuitively studied by the eigenvalues of this matrix. Furthermore, by employing the knowledge gained from this analysis, a real-Time cycle to cycle variable slope compensation method is proposed to guarantee a satisfactory performance of the converter with an extended range of stable operation. Outcomes show that systems can regain stability by applying the proposed method within a few time periods of switching cycles. The numerical and analytical results validate the theoretical analysis, and experimental results verify the effectiveness of the proposed approach

Power Factor Correction (PFC) of AC-DC system using boost-converter

In the present situation, the evolution of growing in computers, laptops, uninterrupted power supplies, telecom and biomedical equipment has become overpowering. Hence, the utilization of such equipment results high power consumption and small power density which provided a large market to Distributed Power System (DPS). Power conditioning; typically rectification is essential usually for electronics equipment. Rectifier behaves as nonlinear load producing non-sinusoidal line current due to the nonlinear input characteristic. There are numbers of international standards to limit the harmonic content, caused due to the line currents of equipment coupled to electricity distribution networks. Accordingly, a reduction in line current harmonics, or Power Factor Correction – PFC is vital. This idea is the inspiration to this research effort. The objective is to improve the power factor nearly unity with minimum Total Harmonic Distortion (THD).For this thesis work small EMI (LC) passive PFC and Boost Converter active PFC are presented with suitable switching control.There are some major conventional control techniques that are implemented for the thesis work, which are; 1) Peak Current Control 2) Average Current Control 3) PI Control. Also for improved dynamic response and large stability range at high frequency the nonlinear controllers; 1) Dynamic Evolution Controller and 2) Sliding Mode Controller are applied. For each cases the input power factor is closed to unity and the line current waveform is observed as sinusoidal with THD percentage is in the tolerate limit

Self-Excited Single-Stage Power Factor Correction Driving Circuit for LED Lighting

This pa per proposes a self-excited single-stage high power factor LED lighting driving circuit. Being featured with power factor correction capability without needing any control devices, the proposed circuit structure is with low cost and suitable for commercial production. The power factor correction function is accomplished by using inductor in combination with a half-bridge quasi resonant converter to achieve active switching and yield out voltage regulation according to load requirement. Furthermore, the zero-voltage switching in the half-bridge converter can be attained to promote the overall performance efficiency of the proposed circuit. Finally, the validity and production availability of the proposed circuit will be verified as well

Stability analysis and control of DC-DC converters using nonlinear methodologies

PhD ThesisSwitched mode DC-DC converters exhibit a variety of complex behaviours in power electronics systems, such as sudden changes in operating region, bifurcation and chaotic operation. These unexpected random-like behaviours lead the converter to function outside of the normal periodic operation, increasing the potential to generate electromagnetic interference degrading conversion efficiency and in the worst-case scenario a loss of control leading to catastrophic failure. The rapidly growing market for switched mode power DC-DC converters demands more functionality at lower cost. In order to achieve this, DC-DC converters must operate reliably at all load conditions including boundary conditions. Over the last decade researchers have focused on these boundary conditions as well as nonlinear phenomena in power switching converters, leading to different theoretical and analytical approaches. However, the most interesting results are based on abstract mathematical forms, which cannot be directly applied to the design of practical systems for industrial applications. In this thesis, an analytic methodology for DC-DC converters is used to fully determine the inherent nonlinear dynamics. System stability can be indicated by the derived Monodromy matrix which includes comprehensive information concerning converter parameters and the control loop. This methodology can be applied in further stability analysis, such as of the influence of parasitic parameters or the effect of constant power load, and can furthermore be extended to interleaved operating converters to study the interaction effect of switching operations. From this analysis, advanced control algorithms are also developed to guarantee the satisfactory performance of the converter, avoiding nonlinear behaviours such as fast- and slowscale bifurcations. The numerical and analytical results validate the theoretical analysis, and experimental results with an interleaved boost converter verify the effectiveness of the proposed approach.Engineering and Physical Sciences Research Council (EPSRC), China Scholarship Council (CSC), and school of Electrical and Electronic Engineerin

Power Quality in Electrified Transportation Systems

"Power Quality in Electrified Transportation Systems" has covered interesting horizontal topics over diversified transportation technologies, ranging from railways to electric vehicles and ships. Although the attention is chiefly focused on typical railway issues such as harmonics, resonances and reactive power flow compensation, the integration of electric vehicles plays a significant role. The book is completed by some additional significant contributions, focusing on the interpretation of Power Quality phenomena propagation in railways using the fundamentals of electromagnetic theory and on electric ships in the light of the latest standardization efforts