Buck-boost Converter Operating Research Articles

A Step-by-Step Design for Low-Pass Input Filter of the Single-Stage Converter

Active power factor correction converters are often introduced as the front stage of power electronic equipment to improve the power factor and eliminate higher harmonics. A Boost or Buck-Boost converter operating in discontinuous current mode is always adopted to achieve high power factor correction. In addition, the input current contains a large amount of higher harmonics, and a low-pass input filter is commonly adopted to filter it out. In this paper, a single-stage high-frequency AC/AC converter is taken as an example to demonstrate the design method of a passive low-pass filter. Firstly, the input side of the grid needs to meet the power factor and harmonic requirements. The preset parameters are set to a range to characterize the performance of the LC filter. The quantitative design method of input filter is proposed and summarized. Moreover, the sensitivity of the filter parameters is analyzed, providing a direction in practical applications. Preset parameters are all proved to conform to the preset range through PSIM simulation. Finally, a 130-W prototype is established to verify the correction of proposed design method. The power factor is around 0.935 and harmonic content in the input current is about 26.4%. All requirements can be satisfied.

A Transformer less Buck Boost Converter with Positive Output Voltage

Some industrial applications require high step-up and step-down voltage gain. The transformer less buck-boost converter has high voltage gain than that of traditional buck-boost converter without extreme duty cycles. A transformer less buck-boost converter with simple structure is obtained by inserting an additional switched network into the traditional buck-boost converter. The two power switches of the buck-boost converter operate synchronously. The operating principles of the buck-boost converter operating in continuous conduction modes are presented. A new buck- boost converter is presented by providing a feedback to the converter. By this, constant output voltage can be maintained under varying load conditions in both buck and boost operation. The output voltage of 40V (step—up mode)/8V (step down mode) is obtained with input voltage 18V and the outcomes are approved through recreation using PSIM MODEL.

Control of the Bidirectional Buck-Boost Converter Operating in Boundary Conduction Mode to Provide Hold-Up Time Extension

A hold-up time extension circuit (HTEC) is used to charge and discharge an auxiliary capacitor. This capacitor stores the energy required to extend the operation time of critical loads experiencing short duration failures (SDF) at the DC bus to which they are connected. This paper presents complete modeling and a control-wise approach to a parallel HTEC based on the bidirectional buck-boost converter, which operates in Boundary Conduction Mode (BCM) with a variable switching frequency. The circuit permanently regulates the voltage of the auxiliary capacitor as well as the voltage of the DC bus during SDF, which is uncommon in industrial versions of HTEC. Enforcing the operation in BCM allows a reduction in the size of the inductor in the converter without requiring additional control circuitry. The entire behavior of the proposed HTEC, in all its operation modes, was analyzed theoretically and validated using simulation and experimental results, showing the potential of the circuit to be used in real applications.

A New Transformerless Buck–Boost Converter With Positive Output Voltage

A new transformerless buck–boost converter with simple structure is proposed in this study. Compared with the traditional buck–boost converter, the proposed buck–boost converter’s voltage gain is squared times of the former’s and its output voltage polarity is positive. These advantages enable it to work in a wider range of positive output. The two power switches of the proposed buck–boost converter operate synchronously. In the continuous conduction mode (CCM), two inductors are magnetized and two capacitors are discharged during the switch-on period, while two inductors are demagnetized and two capacitors are charged during the switch-off period. The operating principles, the steady-state analyses, and the small-signal model for the proposed buck–boost converter operating in CCM are presented in detail. The power electronics simulator (PSIM) and the circuit experiments are provided to validate the effectiveness of the proposed buck–boost converter.

Chaos control of voltage mode controlled buck-boost converter

Due to the limitation to the development level of modern science and technology, DC-DC (where DC stands for direct current) converters operating in chaotic state cannot be used to achieve some desired goals yet and the chaotic phenomena occurring in DC-DC converters are almost restrained. For DC-DC converter operating in continuous conduction mode (CCM), its characteristic has been widely studied, but DC-DC converter needs to operate in discontinuous conduction mode (DCM) at light load. Because if it always works in CCM, the inductor current will be less than zero when the load is light, which will increase conduction loss and reduce conversion efficiency. Moreover, DCM operation is frequently encountered, since power converters are usually required to operate with loads removed. For buck-boost converter, the obvious oscillation will appear when it works under the condition of varying operating point, so it is difficult to control. Considering the reasons above, the voltage mode controlled buck-boost converter operating in DCM is chosen to be studied to verify the validity of the two control methods presented in this paper. Under a certain condition, chaos and bifurcation will occur in the voltage mode controlled buck-boost converter operating in DCM. Having discussed its chaotic phenomenon, in this paper we present two ways to control the system to operate stably in one-cycle state. The first way is the self-controlling delayed feedback control method. The basic idea of this method is to use the difference between the delayed output signal and the output signal to form a feedback signal, and return it to the control circuit in a form of negative feedback to control the output signal. The simulation results show that the self-controlling delayed feedback control method can make the system which has already entered into chaos operate stably in one-cycle state. Besides, its dynamic response speed is fast and it does not change the system frequency. However, this method fails to work when the disturbance is too large. Therefore, the self-controlling delayed feedback control method is more suitable for small disturbance condition. The second way is the improved sliding mode control method. The basic idea of the sliding mode control is to design a switching function to determine a switching surface which represents a desired system dynamics, then, design a variable structure control law to drive any state to reach the switching surface, therefore, the sliding mode takes place and the system follows the desired dynamics. The simulation results show that the improved sliding mode control method can force the system which has already entered into chaos to operate stably in one-cycle state even when the system encounters large disturbance. In addition, although it is more complicated to design, it has great dynamic response characteristics and excellent robustness. Because the methods presented in this paper do not rely on the buck-boost converter itself, both methods can be used to control other DC-DC converters. When the disturbance is small, the self-controlling delayed feedback control method should be considered first, for it is easier to achieve. When the system encounters large disturbances the sliding mode control method has the priority, because this method is valid while the self-controlling delayed feedback control method may fails under such a condition.

Effect of Circuit Parameters on Stability of Voltage-fed Buck-Boost Converter in Discontinuous Conduction Mode

The state transition matrix are obtained by solving state equations in terms of Laplace inverse transformation and Cayley-Hamilton theorem, and an establishment of a precise discrete-iterative mapping of the voltage-fed buck-boost converter operating in discontinuous conduction mode is made. On the basis of the mapping, the converter bifurcation diagrams and Lyapunov exponent diagrams with the input voltage, the resistance, the inductance and the capacitance as the bifurcation parameters are obtained, and the effect of the parameters on the system stability is deeply studied. The results obtained show that they have a great influence on the stability of the system, and the general trend is that the increase of either the voltage-fed coefficient, input voltage or the load resistance, or the decrease of the filtering inductance, capacitance will make the system stability become poorer, and that all the parameters have a critical value, and when they are greater or less than the values, the system will go through stable 1T orbits, stable 2T orbits, 4T orbits, 8T orbits and eventually approaches chaos.

A PFC Based BLDCM Drive for Low Power Household Appliances

This work presents a low cost PFC (Power Factor Correction) based BLDCM (Brushless DC Motor) drive targeting low power household appliances. Development of a highly efficient BLDCM drive with minimum amount of sensing requirement is the primary objective of this work. The switching losses in the VSI (Voltage Source Inverter) feeding BLDCM is reduced by electronically commutating the BLDCM and controlling its speed by controlling the voltage of the DC bus. A PFC buck-boost converter is used as a front-end converter due to its simplicity in design, minimum number of component count and its ability to buck and boost the voltage to control the speed over a wide range. The PFC buck-boost converter operating in DICM (Discontinuous Inductor Current Mode) is used for the control of DC bus voltage. An inherent PFC is achieved for variation of speed over a wide range at universal AC mains (90–265 V). The obtained PQ (Power Quality) indices are within the recommended limits of international PQ standards IEC 61000–3-2. The performance of proposed BLDCM drive is simulated in MATLAB/Simulink environment and validated experimentally on a developed prototype of the drive.

LED Lamp Power Supply without Electrolytic Capacitors based on Integrated Double Buck-Boost Converter Operating in Full DCM

In this paper the integrated double buck-boost converter (IDBBC) operating with both stages in discontinuous conduction mode (DCM) is analyzed. The converter is intended to supply high-voltage LED lamps from the mains, typically in street lighting applications. A high input power factor is assured by operating the first stage in DCM, thus complying with current harmonic injection standards. In this work, the second stage is also operated in DCM as an option to the continuous conduction mode (CCM) that has been studied in a previous paper. The behavior of the converter with both stages in DCM is compared with that of the converter operation with the second stage in CCM. It is demonstrated that with both converters operating in DCM the filter capacitances are reduced even further, allowing for the use of long-life non-electrolytic capacitors. A laboratory prototype to supply a 70 W LED lamp with nominal voltage of 200 V from a 230 V/50 Hz mains maintaining the same design conditions as in the previous work is presented. A comparison of both prototypes is also carried out.

Fractional order Buck–Boost converter in CCM: modelling, analysis and simulations

In this paper, the modelling, analysis and the power electronics simulator (PSIM) simulations of the fractional order Buck–Boost converter operating in continuous conduction mode (CCM) operation are investigated. Based on the three-terminal switch device method, the average circuit model of the fractional order Buck–Boost converter is established, and the corresponding DC equivalent circuit model and AC small signal equivalent circuit model are presented. And then, the equilibrium point and the transfer functions are derived. It is found that the equilibrium point is not influenced by the inductor’s or the capacitor’s order, but both these orders are included in the derived transfer functions. Finally, the comparisons between the theoretical analysis and the PSIM simulations are given for confirmation.

Harvesting energy via electromagnetic damper: Application to bridge stay cables

Energy harvesting from ambient vibration is an emerging and promising solution to the power supply problem associated with autonomous sensors. This article proposes a novel strategy of harvesting damping energy from vibration control devices. A novel system, termed electromagnetic damper cum energy harvester, is employed to fulfill both vibration damping and energy harvesting functions. Electromagnetic damper cum energy harvester is essentially an electromagnetic device connected to a specially designed energy harvesting circuit, which is a buck–boost converter operating in a discontinuous conduction mode. The energy harvesting circuit can achieve satisfactory efficiency without any feedback loop. The effectiveness of the dual-function electromagnetic damper cum energy harvester is demonstrated through a numerical case study of bridge stay cables under wind excitations, in which the major parameters of electromagnetic damper cum energy harvester are determined through a simple design approach. Simulation results project average output power ranging from 82.5 to 2396.8 mW at a wind speed of 9–15 m/s, corresponding to an overall efficiency of 42.3%. The dual-function electromagnetic damper cum energy harvester also exhibits vibration control performance comparable to an optimally designed viscous fluid damper.

A Straightforward Methodology to Modeling High Power Factor AC–DC Converters

In this paper, a straightforward methodology to modeling high power factor (HPF) ac-dc converters is presented. The proposed methodology is based on the averaging technique directly applied to the converter under modeling. An averaged large-signal equivalent circuit is thus generated, which is useful to perform extremely fast simulations. From the large-signal model, both a steady-state and a small-signal analysis can be carried out to completely model the converter, achieving any desired steady-state characteristic and small-signal transfer function. The presented methodology is very intuitive and allows designers to achieve a natural understanding of the converter behavior. The methodology is illustrated with a HPF buck-boost converter operating in discontinuous conduction mode. Simulation and experimental results are provided to validate the proposed methodology.

High‐efficiency two‐switch tri‐state buck–boost power factor correction converter with fast dynamic response and low‐inductor current ripple

Two-switch tri-state buck-boost power factor correction (PFC) converter operating in pseudo-continuous conduction mode is proposed and analysed in this study. Different from tri-state boost PFC converter, the proposed two-switch tri-state buck-boost PFC converter does not need additional power switch to provide the additional degree of control freedom. Therefore it does not increase the complexity and affect the power conversion efficiency of the PFC converter as in the case of tri-state boost PFC converter. For the proposed two-switch tri-state buck-boost PFC converter, the current control loop and voltage control loop are decoupled, a simple voltage control loop with faster dynamic response can be designed to realise output voltage regulation and the additional degree of control freedom introduced by inductor current freewheeling stage helps to achieve unity power factor control. The operation principle, the input current, the inductor current ripple, the switch component stress and the small-signal characteristics of the proposed two-switch tri-state buck-boost PFC converter are analysed. The simulation and experimental results show that the proposed two-switch tri-state buck-boost PFC converter benefits with fast dynamic response, high-efficiency and low-inductor current ripple over single-switch buck-boost PFC converter or two-switch buck-boost PFC converter operating in continuous conduction mode and discontinuous conduction mode.

A Study on LED Retrofit Solutions for Low-Voltage Halogen Cycle Lamps

In this paper, a study on LED retrofit solutions for low-voltage halogen cycle lamps is conducted. In the first part of this paper, a lamp based on a LED array is designed to operate in substitution of a 12-V/50-W halogen lamp, for lighting fixtures in which these lamps are supplied using a line transformer. The design includes the selection of an adequate LED array in terms of lumen output and color temperature and the calculation of the necessary heatsink to assure the correct operation of the LED lamp within the selected temperature range. In the second part of this paper, a passive converter based on a bridge rectifier and a limiting resistance is studied and tested in the laboratory. Next, an active solution based on a buck–boost converter operating in discontinuous conduction mode is designed and experimentally evaluated. Finally, a comparison in terms of input power factor, input current harmonic content, LED current ripple, LED current regulation, efficiency, and photometric characteristics is carried out.

Investigation of the Mechanism of Period-doubling Bifurcation in Voltage Mode Controlled Buck-Boost Converter

An investigation of the mechanism of period-doubling bifurcation in a voltage mode controlled buck-boost converter operating in discontinuous conduction mode is conducted from the viewpoint of nonlinear dynamical systems. The discrete iterative model describing the dynamics of the close-loop is derived. Period-doubling bifurcation occurs at certain values of the feedback factor. Results from numerical simulations and experiments are provided to verify the evolution of perioddoubling bifurcation, and the results are consistent with the theoretical analysis. These results show that the buck-boost converters exhibit a wide range of nonlinear behavior, and the system exhibits a typical period-doubling bifurcation route to chaos under particular operating conditions.

Time Domain Analysis of Steady State Response in Linear Periodic Systems and Its Application to Switching Converters

AbstractThis note discusses the steady state response of a linear periodic system with a periodic input, especially for linear systems with periodic and piecewise continuous coefficients. The first order approximation of the steady state response with respect to the period of time is obtained for general linear periodic systems. This result is then applied to analyze the buck-boost converter operating in continuous conduction mode. This mathematically clarifies conventional results of switching converters which have been deduced under physical inspections or assumptions.

Mode shift and stability control of a current mode controlled buck-boost converter operating in discontinuous conduction mode with ramp compensation

By establishing the discrete iterative mapping model of a current mode controlled buck-boost converter, this paper studies the mechanism of mode shift and stability control of the buck-boost converter operating in discontinuous conduction mode with a ramp compensation current. With the bifurcation diagram, Lyapunov exponent spectrum, time-domain waveform and parameter space map, the performance of the buck-boost converter circuit utilizing a compensating ramp current has been analysed. The obtained results indicate that the system trajectory is weakly chaotic and strongly intermittent under discontinuous conduction mode. By using ramp compensation, the buck-boost converter can shift from discontinuous conduction mode to continuous conduction mode, and effectively operates in the stable period-one region.

Border collision bifurcations and chaos in a class of piecewise smooth systems w ith two boundaries

A class of piecewise smooth maps with three zones is derived to describe the dynamics of a current-programmed Buck-Boost converter operating in a discontinuous mode. The numerical simulation is carried out and the bifurcation diagrams w ith the input voltage as a parameter are obtained. It is shown that, when a bifu rcation occurs, some eigenvalues of the Jacobian matrix jumps over the unit circ le in a discontinuous way, and there are always some orbit points lying on the b oundaries which separate different regions in the phase plane. It is concluded t hat border collision bifurcations could occur when the input voltage varies, for example, a bifurcation from a periodic orbit to another periodic orbit or chaot ic orbit.

AC-LFR concept applied to modular photovoltaic power conversion chains

Modular inverters are presented for grid-connected photovoltaic systems based on the loss-free resistor concept. The basic module consists of a cascade connection of a buck-boost converter operating in discontinuous conduction mode and a push-pull switching inverter. The DC power of the photovoltaic module is transferred by the buck-boost stage to the push-pull converter, which transforms this power into AC power compatible with grid connection. Maximum power point tracking is achieved by matching the panel impedance at the maximum power point and the buck-boost input impedance. Two alternatives for building modular structures for N panels are investigated. Experimental and simulation results of both modular alternatives are presented.