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Power quality improvement in switched mode power supplies using two stage DC-DC converter
S Singh, G Bhuvaneswari, B Singh
International Journal of Engineering, Science and Technology , 2012,
Abstract: This paper deals with an improved power quality multiple output switched mode power supply (SMPS) using two stage DCDC converter. A non-isolated buck-boost DC-DC converter is used as the first stage whereas single ended primary inductance converter (SEPIC) is used in the second stage. The first stage of buck-boost converter is designed in discontinuous conduction mode (DCM) for inherent power factor (PF) correction. Design and simulations of the two stage DC-DC converter with load variations on the SMPS are performed in MATLAB software to demonstrate the effectiveness of the multiple output DC-DC converter to have a stiff voltage regulation and negligible ripple.
Vivek Naithani,Dr.A.N.Tiwari,Smita Dobhal
International Journal of Engineering Science and Technology , 2012,
Abstract: A current-shaper SEPIC converter for high brightness LEDs is presented. Due to the recent advancement in the light emitting diode (LED) technology, high brightness white LED becomes feasible in residential, industry and commercial applications to replace the incandescent bulbs, halogen bulbs, and even compact fluorescent lightbulbs. In these offline applications, high power factor, and low harmonics are of primary importance. A SEPIC converter is particularly suitable for non-isolated application since it is single-stage, and can step up or step down, and high power factor as it is run in discontinuous conduction mode. A current feedback loop is proposed to control the LED brightness. This circuit has the advantages of one stage of power conversion, no need to sense the input voltage, simple feedback control, and voltage step-up and down, high power factor and dimmable LED current.
A Single Stage High Power Factor Supply Based on Integrated Buck Flyback Converter
International Journal of Advanced Research in Electrical, Electronics and Instrumentation Engineering , 2013,
Abstract: In recent years, power converters are used to get high power factor. This paper presents an integrated converter topology for driving HB LEDs which provides high power factor. The integrated buck flyback converter is a single stage, low cost, high power factor AC-DC converter with fast output regulation. The converter is used to provide power factor correction in streetlight application. To obtain high power factor, the buck stage and flyback stage are operated in discontinuous mode. Dimming operation of HB LED is also described. A closed loop is used for enabling the PWM dimming. The simulation studies using MATLAB/Simulink is also presented. Hardware setup of open loop is described.
Analysis of medium-frequency oscillation in the Boost power factor correction converter with average current mode control

Wang Fa-Qiang,Zhang Hao,Ma Xi-Kui,Li Xiu-Ming,

物理学报 , 2009,
Abstract: On the assumption that the input voltage can be replaced by its RMS value and the frequencies of the inductor current and the output voltage are much lower than the switching frequency of the converter, the small-signal model of Boost PFC converter is constructed and the medium-frequency oscillation in Boost PFC converter is studied. The underlying mechanism of this nonlinear phenomenon is analyzed and the stability conditions are also given. These obtained results indicate that this type of nonlinear phenomenon is different from the fast- and slow-scale instabilities, and the main characteristic of this type of nonlinear phenomena is that its oscillation frequency lies between the line frequency and the switching frequency. Finally, an experimental circuit is designed, and its experimental results agree very well with the simulation results.
A State Space Modeling of Non-Isolated Bidirectional DC-DC Converter with Active Switch  [PDF]
J. Barsana Banu, M. Balasingh Moses
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.74018
Abstract: In this paper, analysis, design and implementation of non-isolated soft-switching bidirectional DC-DC converter with an active switch are described. The proposed topology gives the output voltage as twice as the input voltage and enhances the efficiency up to 94.5% and 92.9% for boost and buck mode operation by proper selection of the duty cycle. Soft switching can be achieved at both steps up and step down operating modes. Small signal analysis based on state space averaging and transfer functions have been presented in detail for the proposed converter. Finally, the feasibility of the desired converter is confirmed to mat lab simulation and investigational results.
Research of an Efficient LED Lighting Driver Based on Boost-Buck Converter  [PDF]
Renbo Xu, Yongzhi Li, Lixin Zhong, Jiaming Liu
Circuits and Systems (CS) , 2014, DOI: 10.4236/cs.2014.56017

Boost-Buck converter is widely used in LED lighting drivers. In this paper, Boost-Buck main circuit related characteristics are firstly discussed, and then a new Boost-Buck high power efficient double loop control strategy is built by adopting error amplifier and integrator control method. It is demonstrated that the new system has many advantages such as high efficiency, fast response, strong anti-interference, good stability after analyses and simulations of its working dynamic characteristics.

Embedded Controlled Isolated Bidirectional Full-Bridge DC-DC Converter with Flyback Snubber  [PDF]
D. Kirubakaran,Rama Reddy Sathi
Advances in Power Electronics , 2012, DOI: 10.1155/2012/730473
Abstract: An isolated bidirectional full-bridge DC-DC converter with flyback snubber for supplying a resistive load is simulated and experimentally verified. The DC-DC converter for high conversion ratio, high output power, and soft start-up capability is presented in this paper. The circuit consists of a capacitor, a diode, and a flyback converter. These components help to clamp the voltage spikes caused by the current difference between the current fed inductor and leakage inductance of the isolation transformer. The switches are operated by soft-switching technology. The suppression of inrush current which is usually found in the boost mode start-up transition is presented here. The simulated and experimental results for output voltage, output current, and power for both buck and boost modes are presented. 1. Introduction A DC-DC converter converts a source of direct current(DC) from onevoltagelevel to another. These converters are important in portable electronic devices such as cellular phonesandlaptop computers, which are supplied with power from batteries primarily. The ordinary circuit of a DC-DC converter for high power applications typically includes a bidirectional full-bridge DC-DC converter [1–3]. The current difference between the inductor and isolation transformer does not ensure a well-defined output voltage and is characterized by less reliability and efficiency. The output voltage contains voltage spikes. An active commutation can be used to control the current in the leakage inductance [4]. But it requires an additional clamping circuit to suppress the voltage spikes. An RCD passive snubber can be used to clamp the voltage. A buck converter was employed to replace RCD snubber. But it still needed complex clamping circuit [5, 6]. Active clamping increases the current stress on switches. Soft-switching capability can be used, but it is not suitable for step-down operation. In this scheme of DC-DC converter with flyback snubber (Figure 1), the snubber recycles the absorbed energy in the clamping capacitor. The voltage of the clamping capacitor can be regulated by operating the flyback snubber independently. The current does not circulate through the full-bridge switches, and hence the current stress can be reduced, improving the system reliability significantly. Figure 1: Isolated bidirectional full-bridge Dc-Dc converter with flyback snubber. 2. Configuration and Operation The operating principle of the circuit consists of two modes: (i)step-up conversion,(ii)step-down conversion. The modes of operation of boost mode are shown in Figure 2 and of
Nonlinear Phenomena in Buck-Boost Power Factor Correction Converter  [cached]
Mehrnoosh Vatani,Soodabeh Soleymani,Mehrdad Ahmadi Kamarposhti
Research Journal of Applied Sciences, Engineering and Technology , 2013,
Abstract: Buck-Boost Power-Factor-Correction (PFC) converter with Average-Current-Model (ACM) control is a nonlinear circuit because of the multiplier using and large change in the duty cycle, so its stability analysis must be studied by nonlinear model. In this paper double averaging method is used for describing the model of this converter. By this model we would be able to explain the low frequency dynamics of the system and identify stability boundaries according to circuit parameters and also nonlinear phenomena of this converter are detected.
Estimation of reliability of a interleaving PFC boost converter  [PDF]
Gulam Amer Sandepudi,Rao Srinivasa
Serbian Journal of Electrical Engineering , 2010, DOI: 10.2298/sjee1002205g
Abstract: Reliability plays an important role in power supplies. For other electronic equipment, a certain failure mode, at least for a part of the total system, can often be employed without serious (critical) effects. However, for power supply no such condition can be accepted, since very high demands on its reliability must be achieved. At higher power levels, the continuous conduction mode (CCM) boost converter is preferred topology for implementation a front end with PFC. As a result, significant efforts have been made to improve the performance of high boost converter. This paper is one of the efforts for improving the performance of the converter from the reliability point of view. In this paper, interleaving boost power factor correction converter is simulated with single switch in continuous conduction mode (CCM), discontinuous conduction mode (DCM) and critical conduction mode (CRM) under different output power ratings. Results of the converter are explored from reliability point of view.
Simulations and Analysis and Operating Regime as Rectifier with Power Factor Correction of Two - Quadrant Converter with RNSIC  [cached]
Advances in Electrical and Computer Engineering , 2009,
Abstract: In this paper, a new topology for a two-quadrant converter is presented. In the AC/DC transfer mode, the converter works as a rectifier with near sinusoidal input currents (RNSIC), while in the DC/AC transfer mode it works as a square-wave pulse switching inverter. We offer some suggestions for the converter design and realize a comparison with a two-quadrant PWM converter. The new converter is characterized by smaller power losses, reduced EMI problems and higher reliability.
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