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 diagrazn, 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.

Modeling and dynamics analysis of the fractional-order Buck-Boost converter in continuous conduction mode

In this paper, the fractional-order mathematical model and the fractional-order state-space averaging model of the Buck-Boost converter in continuous conduction mode （CCM） are established based on the fractional calculus and the Adomian decomposition method. Some dynamical properties of the current-mode controlled fractional-order Buck- Boost converter are analysed. The simulation is accomplished by using SIMULINK. Numerical simulations are presented to verify the analytical results and we find that bifurcation points will be moved backward as α and β vary. At the same time, the simulation results show that the converter goes through different routes to chaos.

Sampled-data modeling and dynamical effect of output-capacitor time-constant for valley voltage-mode controlled buck-boost converter

By analyzing the output voltage ripple of a buck-boost converter with large equivalent series resistance（ESR） of output capacitor, one valley voltage-mode controller for buck-boost converter is proposed. Considering the fact that the increasing and decreasing slopes of the inductor current are assumed to be constant during each switching cycle, an especial sampleddata model of valley voltage-mode controlled buck-boost converter is established. Based on this model, the dynamical effect of an output-capacitor time-constant on the valley voltage-mode controlled buck-boost converter is revealed and analyzed via the bifurcation diagrams, the movements of eigenvalues, the Lyapunov exponent spectra, the boundary equations,and the operating-state regions. It is found that with gradual reduction of output-capacitor time-constant, the buck-boost converter in continuous conduction mode（CCM） shows the evolutive dynamic behavior from period-1 to period-2, period-4, period-8, chaos, and invalid state. The stability boundary and the invalidated boundary are derived theoretically by stability analysis, where the stable state of valley voltage-mode controlled buck-boost converter can enter into an unstable state, and the converter can shift from the operation region to a forbidden region. These results verified by time-domain waveforms and phase portraits of both simulation and experiment indicate that the sampled-data model is correct and the time constant of the output capacitor is a critical factor for valley voltage-mode controlled buck-boost converter, which has a significant effect on the dynamics as well as control stability.

Synthesis of Nonlinear Control of Switching Topologies of Buck-Boost Converter Using Fuzzy Logic on Field Programmable Gate Array (FPGA)

An intelligent fuzzy logic inference pipeline for the control of a dc-dc buck-boost converter was designed and built using a semi-custom VLSI chip. The fuzzy linguistics describing the switching topologies of the converter was mapped into a look-up table that was synthesized into a set of Boolean equations. A VLSI chip–a field programmable gate array (FPGA) was used to implement the Boolean equations. Features include the size of RAM chip independent of number of rules in the knowledge base, on-chip fuzzification and defuzzification, faster response with speeds over giga fuzzy logic inferences per sec (FLIPS), and an inexpensive VLSI chip. The key application areas are: 1) on-chip integrated controllers;and 2) on-chip co-integration for entire system of sensors, circuits, controllers, and detectors for building complete instrument systems.

A high precision electron beam welder power supply based on buck-boost converter using fuzzy PID control

A novel electron beam welder （ EBW） power supply was developed. Compared with the traditional 3-phase contrail 12-pulse rectifying supplies, it requires a much lower step-up ratio transformer, but a much less output ripple voltage can be obtained. The design of the main circuit of this new power supply is based on PWM buck-boost converter topology. In developing the system a fuzzy PID control method is adopted because of the strong non-linearity and big signal working conditions of the circuit system. The SABER-MATLAB models and fuzzy algorithm were used in developing the fuzzy PID controller. The co-simulation and experimental results displayed that the unit introduced herein has the characteristics of high control precision and antinterference capability.

Non-inverting buck-boost DC-DC converter based on constant inductor current control

The hysteresis control combined with PWM control non-inverting buck-boost was proposed to improve the light load efficiency and power density.The constant inductor current control(CICC)was established to mitigate the dependence on the external components and device variation and make smooth transition between hysteresis control loop and pulse width modulation(PWM)control loop.The small signal model was deduced for the buck and boost operation mode.The inductor current slope control(ICSC)was proposed to implement the automatic mode transition between buck and boost mode in one switching cycle.The results show that the converter prototype has good dynamic response capability,achieving 94%efficiency and 95%peak efficiency at full 10 A load current.

FCS-MPC for four-switch three-phase AC-DC converters with DC-link capacitor voltage balancing

Due to the decrease in the number of switches for the four-switch three-phase alternating current-direct current(FSTP AC-DC)converter,it can easily lead to DC-link capacitor voltage imbalance and the system stability reduction.In order to solve these problems,a finite control set model predictive control(FCS-MPC)for FSTP AC-DC converters with DC-link capacitor voltage balancing is proposed.In this strategy,in order to facilitate calculation,theαβcoordinate system model is established and all voltage vectors are evaluated by establishing a cost function.During the whole process,phase locked loop(PLL)and complex modulation strategy are not required.In the new established cost function,the additional objective term of suppressing capacitor voltage fluctuation is to eliminate effectively the capacitor voltages oscillations and deviations and improve the system reliability.The simulation results show that the proposed strategy can keep the capacitor voltage balancing and has good dynamic and static performance.

Direct Model Predictive Control of Noninverting Buck-boost DC-DC Converter

In this paper, direct model predictive control(DMPC) of the noninverting buck-boost DC-DC converter with magnetic coupling between input and output is proposed. Unlike most of the other converters, the subject converter has the advantage of exhibiting minimum phase behavior in the boost mode. However, a major issue that arises in the classical control of the converter is the dead zone near the transition of the buck and boost mode. The reason for the dead zone is practically unrealizable duty cycles, which are close to zero or unity, of pulse width modulation(PWM) near the transition region. To overcome this issue, we propose to use DMPC. In DMPC, the switches are manipulated directly by the controller without the need of PWM.Thereby, avoiding the dead zone altogether. DMPC also offers several other advantages over classical techniques that include optimality and explicit current constraints. Simulations of the proposed DMPC technique on the converter show that the dead zone has been successfully avoided. Moreover, simulations show that the DMPC technique results in a significantly improved performance as compared to the classical control techniques in terms of response time, reference tracking, and overshoot.

Estimation-Correction Modeling and Chaos Control of Fractional- Order Memristor Load Buck-Boost Converter

A fractional-order memristor load Buck-Boost converter causes periodic system oscillation,electromagnetic noise,and other phenomena due to the frequent switching of the switch in actual operation,which is detrimental to the stable operation of the power electronic converter.It is of great significance to the study of the modeling method and chaos control strategy to suppress the nonlinear behavior of the Buck-Boost converter and expand the safe and stable operation range of the power system.An estimation-correction modeling method based on a fractional active voltage-controlled memristor load peak current Buck-Boost converter is proposed.The discrete numerical solution of the state variables in the continuous mode of the inductor current is derived.The bursting oscillation phenomenon when the system introduces external excitation is analyzed.Using bifurcation,Lyapunov exponent,and phase diagrams,a large number of numerical simulations are performed.The results show that the Buck-Boost converter is chaotic for certain selected parameters,which is the prerequisite for the introduction of the controller.Based on the idea of parameter perturbation and state association,a three-dimensional hybrid control strategy for a fractional memristor Buck-Boost converter is designed.The effectiveness of the control strategy is verified by simulations,and it is confirmed that the system is controlled in a stable periodic state when the external tunable parameter s,which represents the coupling strength between the state variables in the system,gradually decreases in[-0.4,0].Compared with integer-order controlled systems,the stable operating range of fractional-order controlled systems is much larger.

State Variable Model for Considering the Parasitic Inductor Resistance on the Open Loop Performance of DC to DC Converters

This paper shows DC and small-signal circuit models for the PWM DC to DC buck, boost and back/ boost converters with the equivalent series resistance of the inductor. The DC voltage transfer function and the efficiency of the converter are derived from the DC model. Small-signal open-loop characteristics are derived from the small-signal model based on a state variable model. A design example proves the performance of the circuit and verification of the model.

A Generalized State Space Average Model for Parallel DC-to-DC Converters

The high potentiality of integrating renewable energies,such as photovoltaic,into a modern electrical microgrid system,using DC-to-DC converters,raises some issues associated with controller loop design and system stability.The generalized state space average model(GSSAM)concept was consequently introduced to design a DC-to-DC converter controller in order to evaluate DC-to-DC converter performance and to conduct stability studies.This paper presents a GSSAM for parallel DC-to-DC converters,namely:buck,boost,and buck-boost converters.The rationale of this study is that modern electrical systems,such as DC networks,hybrid microgrids,and electric ships,are formed by parallel DC-to-DC converters with separate DC input sources.Therefore,this paper proposes a GSSAM for any number of parallel DC-to-DC converters.The proposed GSSAM is validated and investigated in a time-domain simulation environment,namely a MATLAB/SIMULINK.The study compares the steady-state,transient,and oscillatory performance of the state-space average model with a fully detailed switching model.

Three-phase Voltage-fed Quasi-Z-Source AC-AC Converter

The paper proposes a novel three-phase voltage-fed quasi-Z-source ac-ac converter topology to overcome the shortcomings of the traditional three-phase AC-AC chopper.The quantitative relationship between the output voltage and duty-ratio is deduced by investigating the topology and operating principle.It can provide buck-boost function,and the output voltage of the circuit can keep stable in the case of voltage sagging.Simulation is performed using the MATLAB software,and the experimental circuit is built based on the simulation results,the simulation and experimental results verify the correctness and feasibility of the proposed ac-ac converter topology.

Design of High Efficiency DC-DC Converter for Photovoltaic Solar Home Applications

The solar energy conversion system is very interesting alternative on supplement the electric system generation, due to the persistent cost reduction of the overall system and cleaner power generation. To obtain a stable voltage from an input supply （PV cells） that is higher and lower than the output, a high efficiency and minimum ripple DC-DC converter required in the system for residential power production. Buck-boost converters make it possible to efficiently convert a DC voltage to either a lower or higher voltages. Buck-boost converters are especially useful for PV maximum power tracking purposes, where the objective is to draw maximum possible power from solar panels at all times, regardless of the load. This paper analyzes and describes step by step the process of designing, and simulation of high efficiency low ripple voltage buck-boost DC-DC converter for the photovoltaic solar conversion system applicable to a （typical） single family home based on battery-based systems. The input voltage can typically change from （20 V） initially, down to （5 V）, and provide a regulated voltage within the range of the battery （12 V）. PLECS simulation results provide strong evidences about the high efficiency, minimum ripple voltage, high accuracy, and the usefulness of the system of the proposed converter when applied to either residential or solar home applications.

Application of non-isolated bidirectional DC-DC converters for renewable and sustainable energy systems:a review

The primary challenge in renewable-energy utilization is an energy-storage system involving its power converter.The systems have to promise high efficiency,reliability and durability.Also,all of these can be realized at an economical cost.Buck and boost converters connected in parallel can convert power in both directions.It is the basic non-isolated bidirectional topology commonly used with energy-storage systems.The primary issue with the buck-boost non-isolated bidirectional converter is how to enhance its performance,so the modification involving this topology is still conducted.This paper examines 29 proposed converters from 30 research publications published in the last 10 years,the most recent of which focuses on modified non-isolated bidirectional converters based on the buck-boost topology.These are classified into eight modification schemes,which involve adding new components or circuits to the base topology.Each is evaluated against six parameters:the number of components,control complexity,power-rating applications,soft-switching ability,efficiency outcome and capacity to minimize losses.Moreover,each modified non-isolated bidirectional converter was compared from the renewable-energy-based power-generation-source perspective utilized.Based on these studies,researchers might think of ways to improve the buck-boost converter by changing it to make a new non-isolated bidirectional converter that can be used in systems that need it.

Overview on Fault-Tolerant Four-Switch Three-Phase Voltage Source Converters

With the rapid development and widespread applications of power electronic converters,strong fault-tolerant capability of power electronic converters is required since they play important roles in power systems.In this paper,a review of one of the most promising fault-tolerant topologies for semiconductor open-circuit fault,called four-switch three-phase(FSTP)topology,is presented in terms of modeling analysis,modulation techniques,and control strategies.The configuration of FSTP voltage source converter(VSC)is illustrated.To minimize the negative effects caused by the innate drawbacks of this fault-tolerant converter topology,considerable research has been carried out regarding modulation techniques and control strategies.The modulation principle for FSTP topology is explained in detail,since the performance of FSTP VSCs relies on it.This paper aims to illustrate current research progress on this fault-tolerant FSTP VSC topology.

Behavior an Induction Generator without and with a Voltage Regulator

During the isolated use of a wind system, the output voltage of the self-excited induction generator depends on the variation characteristic of its parameters: the excitation condensers, the drive speed and the load. Therefore, the regulation of the tension appears to be of great interest. We focused on the use of an analogical regulator of tension, with the aim of controlling the tension at the exit of the self-excited induction generator. So we modelled, implanted and simulated a wind system (Self-excited induction generator, converters (AC/DC, DC/DC) and load it) in the Orcad/Pspice environment. In the first time the behaviour of the asynchronous generator was analyzed when the load, the excitation capacitor and the drive speed vary in the absence of any form of regulation. This analysis was conducted with the aim of defining the limits of the machine exploitation. In the second time the functioning mode is controlled by an analogical control of tension. The results of simulation show the good performances of the system during the application of the proposed voltage regulator.

Boost Chopper Behaviors in Solar Photovoltaic System

This paper investigates the behaviors of Boost DC Chopper used in Photovoltaic energy systems where the solar irradiation changes during the day time causing current and voltage changes. Varying the solar irradiation causes output chopper voltage changes in order to keep working at maximum extracted solar power. The chopper voltage changes leading to variable duty cycle operation of chopper switch and causes a significant change in switch losses in terms of the dissipated power. In addition to that the chopper behaviors are studied when the chopper voltage is boosting up to a predetermined reference value leading to a significant change in chopper current, voltage, duty cycle and occurred losses. A mathematical model for chopper performances and switch losses is derived, and a simulation model using Matlab/ Simulink platforms is conducted to follow the chopper behaviors. Simulation results for concreteSUNPOWER panel type SPR-315E-WHT-D with 315 Watts peak indicates that during the daylight time transistors are exposed to complicated changes in their current, voltage and dissipated power. Furthermore changing the output voltage according to load requirements causes heavy stress on the transistor in terms of current, oscillations and losses as well. Simulation results show that there are optimized values of irradiation, chopper voltage and duty cycle where the transistor losses are minimized. In addition to that, projecting the transistor losses over the daylight time at a given irradiation rate shows how these losses vary among the year, and the amount of energy dissipated across the main chopper switch which is around 2970 Whr/yr for the present case. Furthermore, the conducted simulation also shows the occurred in the transistor behaviors when solar irradiation changes, and can be serving for further studies.

Model Predictive Current Control for Low-Cost Shunt Active Power Filter

Performance of a three-phase shunt active power filter(SAPF)relies on the capability of the controller to track the reference current.Therefore,designing an accurate current controller is crucial to guarantee satisfactory SAPF operation.This paper presents a model predictive current controller(MPCC)for a low-cost,four-switch,shunt active power filter for power quality improvement.A four-switch,B4,converter topology is adopted as an SAPF,hence offering a simple,robust,and low-cost solution.In addition,to further reduce overall cost,only two interfacing filter inductors,instead of three,are used to eliminate switching current ripple.The proposed SAPF model MPCC is detailed for implementation,where simulation and experimental results validate effectiveness of the proposed control algorithm showing a 20%improvement in total harmonic distortion compared with a conventional hysteresis band current controller.

A positive Buck-Boost voltage balancer for DC distribution system

This paper analyzes the load unbalance problem and voltage fluctuation problem in a 3-wire DC distribution system.It also analyzes a solution to these problems;a positive Buck-Boost voltage balancer is proposed and explored in order to fulfill the requirements of high quality power supply for the loads on its load side.Compared with the conventional balancer,a positive Buck-Boost converter is added to solve the voltage fluctuation problem,and the theories and methods of the voltage balancer are extended to analyze the working principle,derive the design equations,explore the stability,and calculate the efficiency.Both simulations and small power experiments are carried out to verify the validity of the working principle,the topology,and the control strategy.

Active Cell Balancing Control Strategy for Parallelly Connected LiFePO_(4) Batteries

While several recent studies have focused on elimi-nating the imbalance of energy stored in series-connected battery cells,very little attention has been given to balancing the energy stored in parallel-connected battery cells.As such,this paper aims at presenting a new balancing approach for parallel LiFePO_(4) battery cells.In this regard,a Backpropagation Neural Network(BPNN)based technique is employed to develop a Battery Management System(BMS)that can assess the charging status of all cells and control its operations through a DC/DC Buck-Boost converter.Simulation results demonstrate the effectiveness of the proposed approach in balancing the energy stored in parallel-connected battery cells in which the state of charge(SoC)estimation error is found to be only 1.15%.