ANovel Non-Isolated Cubic DC-DC Converter with High Voltage Gain for Renewable Energy Power Generation System

In recent years,switched inductor(SL)technology,switched capacitor(SC)technology,and switched inductor-capacitor(SL-SC)technology have been widely applied to optimize and improve DC-DC boost converters,which can effectively enhance voltage gain and reduce device stress.To address the issue of low output voltage in current renewable energy power generation systems,this study proposes a novel non-isolated cubic high-gain DC-DC converter based on the traditional quadratic DC-DC boost converter by incorporating a SC and a SL-SC unit.Firstly,the proposed converter’s details are elaborated,including its topology structure,operating mode,voltage gain,device stress,and power loss.Subsequently,a comparative analysis is conducted on the voltage gain and device stress between the proposed converter and other high-gain converters.Then,a closed-loop simulation system is constructed to obtain simulation waveforms of various devices and explore the dynamic performance.Finally,an experimental prototype is built,experimental waveforms are obtained,and the experimental dynamic performance and conversion efficiency are analyzed.The theoretical analysis’s correctness is verified through simulation and experimental results.The proposed converter has advantages such as high voltage gain,low device stress,high conversion efficiency,simple control,and wide input voltage range,achieving a good balance between voltage gain,device stress,and power loss.The proposed converter is well-suited for renewable energy systems and holds theoretical significance and practical value in renewable energy applications.It provides an effective solution to the issue of low output voltage in renewable energy power generation systems.

A Piecewise Linear Slope Compensation Circuit for DC-DC Converters

To prevent sub-harmonic oscillation and improve the stability and load capacity of the system,a piecewise linear slope compensation circuit is designed. Compared with the traditional design, this circuit provides a compensation signal whose slope varies from different duty cycles at - 40-85℃ ,and reduces the negative effect of slope compensation on the system＇s load capacity and transient response. A current mode PWM Boost DC-DC converter employing this slope compensation circuit is implemented in a UMC 0.6μm-BCD process. The results indicate that the circuit works well and effectively,and the load capacity is increased by 20%. The chip area of the piecewise linear slope compensation circuit is 0.01mm^2 ,which consumes only 8μA quiescent current,and the efficiency ranges up to 93%.

Improving Characteristics of Integrated Switched-Capacitor DC-DC Converter by CMOS Technology

An integrated 3.3V/1.2V SC DC-DC converter operating under 10MHz with a fixed duty radio of 0.5 is presented.To improve the output current of the converter,CMOS technology is adopted to fabricate the switching devices,and mutually compensatory circuitry technology is also employed to double the output current furthermore.The simulation results using Hspice simulation software,show that the output currents of a single unit circuit and two unit circuits connected in a mutually compensatory manner of the improved converter is about 12.5mA and 26mA,respectively.The power conversion efficiency of the mutually compensatory circuit can amount to 73%,while its output voltage ripple is less than 1.5%.The converter is fabricated in standard Rohm 0.35μm CMOS technology in Tokyo University of Japan.The test result indicates that the output current of 9.8mA can be obtained from a single unit circuit of the improved converter.

A Novel Hybrid DPWM for Digital DC-DC Converters

We present a new hybrid digital pulse-width modulator （DPWM） for digital DC-DC converters that employs a ring-oscillator/counter structure. Based on a temperature/process compensation technique and a novel digital controller, the proposed DPWM can not only offer temperature/process-independent pulse widths, but also operate at a much higher clock frequency than the existing delay-line/counter DPWM structure. Post-simulation results show that with our DPWM, the system clock frequency reaches 156.9MHz while the worst variation,in a temperature range of 0 to 100℃under all process corners,is only± 9.4%.

Large-areaβ-Ga_(2)O_(3) Schottky barrier diode and its application in DC-DC converters

We demonstrate superb large-area verticalβ-Ga_(2)O_(3)SBDs with a Schottky contact area of 1×1 mm^(2)and obtain a high-efficiency DC-DC converter based on the device.Theβ-Ga_(2)O_(3)SBD can obtain a forward current of 8 A with a forward volt-age of 5 V,and has a reverse breakdown voltage of 612 V.The forward turn-on voltage(VF)and the on-resistance(Ron)are 1.17 V and 0.46Ω,respectively.The conversion efficiency of theβ-Ga_(2)O_(3)SBD-based DC-DC converter is 95.81%.This work indicates the great potential of Ga_(2)O_(3)SBDs and relevant circuits in power electronic applications.

Experimental Evaluation of Medium-Voltage Cascode Gallium Nitride(GaN)Devices for Bidirectional DC-DC Converters

Wide bandgap(WBG)semiconductors,such as silicon carbide(SiC)and gallium nitride(GaN),exhibit superior physical properties and demonstrate great potential for replacing conventional silicon(Si)semiconductors with WBG technology,pushing the boundaries of power devices to handle higher blocking voltages,switching frequencies,output power levels,and operating temperatures.However,tradeoffs in switching performance and converter efficiency when substituting GaN devices for Si and SiC counterparts are not well-defined,especially in a cascode configuration.Additional research with further detailed investigation and analysis is necessitated for medium-voltage GaN devices in power converter applications.Therefore,the aim of this research is to experimentally investigate the impact of emerging 650/900 V cascode GaN devices on bidirectional dc-dc converters that are suitable for energy storage and distributed renewable energy systems.Dynamic characteristics of Si,SiC,and cascode GaN power devices are examined through the double-pulse test(DPT)circuit at different gate resistance values,device currents,and DC bus voltages.Furthermore,the switching behavior and energy loss as well as the rate of voltage and current changes over the time are studied and analyzed at various operating conditions.A 500 W experimental converter prototype is implemented to validate the benefits of cascode GaN devices on the converter operation and performance.Comprehensive analysis of the power losses and efficiency improvements for Si-based,SiC-based,and GaN-based converters are performed and evaluated as the switching frequency,working temperature,and output power level are in-creased.The experimental results reveal significant improvements in switching performance and energy efficiency from the emerging cascode GaN devices in the bidirectional converters.

Simulations of the Performance of Maximum Power Point Tracking Algorithms Based on Experimental Data According to the Topologies of DC-DC Converters

Maximum Power Point Tracking (MPPT) algorithms are now widely used in PV systems independently of the weather conditions. In function of the application, a DC-DC converter topology is chosen without any previous performance test under normal weather conditions. This paper proposes an experimental evaluation of MPPT algorithms according to DC-DC converters topologies, under normal operation conditions. Four widely used MPPT algorithms i.e. Perturb and Observe (P & O), Hill Climbing (HC), Fixed step Increment of Conductance (INCF) and Variable step Increment of Conductance (INCV) are implemented using two topologies of DC-DC converters i.e. buck and boost converters. As input variables to the PV systems, recorded irradiance and temperature, and extracted photovoltaic parameters (ideality factor, series resistance and reverse saturation current) were used. The obtained results show that buck converter has a lot of power losses when controlled by each of the four MPPT algorithms. Meanwhile, boost converter presents a stable output power during the whole day. Once more, the results show that INCV algorithm has the best 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.

SIMULATION STUDY OF CHAOS IN DC-DC CONVERTER

A DC DC buck converter c on trolled by naturally sampled, constant frequency PWM is considered. The existe nce of chaotic solutions and the output performance of the system under differen t circuit parameters are studied. The transforming pattern of system behavior fr om steady state to chaotic is discovered by the cascades of period doubling bi furcation and the cascades of periodic orbit in V I phase space. Accordingl y, it is validated that change of values of the circuit parameters may lead DC DC converter to chaotic motion. Performances of the output ripples fro m steady state to chaotic are analyzed in time and frequency domains respective ly. Some important conclusions are helpful for opt imization design of DC DC converter.

Multi-converter Approach to Higher Power Density DC-DC Converter for 380 V DC Distribution System

Multi-converter approach based on the series and parallel connection topology of modular power converters has been proposed to realize higher power density DC-DC converter. The availability of the proposed approach has been verified through the design consideration and the experiment. The design consideration for two DC-DC converters has been carried out by utilizing the power converter exact loss simulator, and the design parameters to maximize their power densities have been extracted taking the trade-off between the conversion efficiency and the power density into account. The prototypes of a 2,400 W, 256-384 V boost chopper using SiC-MOSFETs and a 300 W, 32-48 V GaN-FETs boost chopper have been also developed based on the design. The SiC chopper achieved the efficiency of 97.8% and the power density of 12,8 W/cm3, and the GaN chopper accomplished 98.9% and 18.6 W/cm3 in the experiment. These results show the validity of the design and the availability of the proposed approach. The multi-converter approach enables the cost reduction of the modular power converters, and contributes to realizing the widespread use of power electronics converters in the future 380 V DC distribution system.

Simulation of multiphase boost DC-DC converter with the stable control strategy

The multiphase boost DC-DC converter with stable control strategy is presented. Multi- phase boost DC-DC converter is designed for high voltage and high power applications, and could be achieved by the adjustment of voltage doubler rectifiers on the secondary side of high frequency transformers. The stable control strategy for three phase boost DC-DC converter has been utilized during simulation in this study and this strategy can be extend to N-number of phases. The stable control strategy consists of only three voltage loops, which are sufficient for appropriate and efficient operation of three phase boost DC-DC converter. With the stable control strategy, the equal power balance sharing can be obtained between input and output. The stability of control strategy has been evaluated by simulating the multiphase boost DC-DC converter for the same and mismatch turn ratios of high frequency transformers. The simulation result is good and the objective of the strategy is a- chieved.

A Novel Single Switch High Gain DC-DC Converter Topology for Renewable Energy Systems

Renewable energy with sources such as photovoltaic(PV)or fuel cells can be utilized for the generation of elec-trical power.But these sources generate fewer voltage values and therefore require high gain converters to match with DC bus voltage in microgrids.These high gain converters can be implemented with switched capacitors to meet the required DC bus voltage.Switched capacitors operate in a series and parallel combination during switch-ing operation and produce high static gain,limits reverse voltage that appears across the components.A novel converter is proposed that satisfies all the features such as high voltage gain,only one switch,forces less potential stress cross the components,ripple current is less.These features of the proposed converter are verified through MATLAB/SIMULINK.

A Novel Regulation Technique and Its Application to Design of Embedded SC DC-DC Converters

An optimized design of the monolithic switched capacitor DC-DC converter is presented.The general topologic circuit and its basic operating principles are discussed theoretically.Circuit equivalent resistance regulation method is proposed as a feasible method to design the on-chip converters.N-channel MOSFETs,instead of Schottky diodes,are used as the diodes in the converters because of their processing compatibility in monolithic fabrication.One more manufacture step,however,is expected to adjust the threshold voltage of the MOSFETs for improving output characteristics of the converters.As an example,a step-up switched-capacitor converter is fabricated in a 2μm p-well double-poly single-metal CMOS technology with breakdown voltage of 15V.Test results indicate that a single sampling cell with 0.4mm 2 of die size can deliver energy up to 0.63mW at 5V output under the condition of 3V input.Efficiency of the tested sample is 68% at 9.8MHz switching frequency...

Extract the Output Signal Characteristics of DC-DC Converter Based on Fourier Descriptor

The precondition of realizing feedback controlling DC DC converter to avoid chaotic state is to judge the behavior of the converter and take corresponding measures. In this paper, the output signals under different circuit parameters of the PWM buck converter have been analyzed. The method of using Fourier descriptor to extract output signals characteristics is put forward and proved to be a gist of identifying and classifying the behavior of DC DC converter. This method can establish a good foundation fo...

Design and Simulation of a Solar Regulator Based on DC-DC Converters Using a Robust Sliding ModeController

The MPPT （maximum power point tracking） is one of the most important features of a regulator system that processes the energy produced by a photovoltaic generator. It is necessary, in fact, to design a controller that is able to set the output value of the voltage and ensure the working within the maximum power point. In this paper, we propose the application of the robust sliding mode control technique to a DC-DC buck converter which is combined with a classical P ＆ O （perturbation and observation） algorithm to enhance the solar system efficiency. Dynamic equations describing the boost converter are derived and a sliding mode controller for a buck converter is designed. It is shown that, this control approach gives good results in terms of robustness toward load and input voltage variations. The effectiveness of the proposed work is verified by the simulation results under PowerSim environment.

Constant Ripple Current Control for Switching DC-DC Converter

The adapted DC-DC converters should be smaller in size and have a small output current ripple to meet the increasing demand for low voltages with high performance and high density micro processors for several microelectronic load applications. This paper proposes a DC-DC converter using variable on-time and variable switching frequency control enhanced constant ripple current control and reduced magnetic components. The proposed converter is realized by making the turn-offtime proportional to the on-time of the converter, according to the input and output voltage, thereby reducing the corresponding current ripple on output voltage in the continuous conduction mode. A Buck DC-DC converter using the proposed control strategy is analyzed in detail, along with some experimental results to show the performance and effectiveness of this converter.

Study on the Reversible DC-DC Converter as Interface between Low and Medium Voltage DC Networks

This paper introduces an isolated reversible DC-DC converter with a particular topology, which benefits from both the NPC （neutral point clamped） structure and the series-parallel connection of converters. The key property of the proposed topology is the output voltage elevation above the blocking capabilities of each switch, without taking to a delicate synchronization of series-connected semiconductors. The converter is composed by two identical cells, each containing a full bridge, a medium frequency transformer and an NPC converter, connected in parallel at the input and in series at the output. The operation principle of each cell, into which a trapezoidal modulation was implemented, is similar to a DAB （dual active bridge）. A new model improves the dynamic performance of the controller. Simulation and experimental results verify the proposed topology, its control and start-up strategy.

A Method to Obtain Complex Transfer Functions of Four Order DC-DC Converters

Two TFs （transfer functions） are needed to analyze switching DC-DC converters in control-voltage mode： the duty-cycle to output-voltage （control to output） and the input-voltage to output-voltage （line to output）. To obtain these TFs a small-signal analysis is required. The CCM （continuous conduction mode） and the DCM （discontinuous conduction mode） analysis are different. When a circuit includes the loss resistances of the components, the number of parameters increases considerably, making manual nodal-loop circuit analysis techniques impractical to obtain the TFs. Moreover, these circuits are bilinear （non-linear） and it is necessary to linearize the equations at a DC operating-point （approximate linearization）. Vorp6rian describes a PWM （pulse-width-modulated） switch model that includes all non-linear parts of the DC-DC switching converters. This model can be linearized and replaced on the switching converter schematic leading to a linear circuit. At this point it is possible to use symbolic analysis programs to obtain these TFs or to simply apply numerical values for either the Bode diagrams or the calculation of poles and zeros. Here we describe an application of Ekrem Cangeici＇s method on X DC-DC converter to obtain control to output and line to output TFs in CCM and DCM including loss resistances. The method presented in this paper is optimized to use in the online publishing platform OctaveRS. Also the control to output TF for PCC （peak current controlled） in CCM is obtained.

Fundamental Study of High Step-down Non-isolated Multicellular DC-DC Converter for Future DC Distribution Systems

A novel high step-down non-isolated DC-DC converter has been proposed. The proposed converter consists of highly efficient non-isolated cell converters using bidirectional semiconductor power devices, and these cell converters are connected in ISOP （input series and output parallel）. The non-isolated ISOP converter achieves high step-down ratio of D/N, operating N cell converters under the duty ratio olD. Availability of the proposed converter has been shown by developing the 48 V-12 V laboratory prototype using two 24 V-12 V cell converters. Design consideration for the 48 V-3 V multicellular converter using four 12 V-3 V cell converters has been also conducted, and the potential to approach the efficiency of 97% has been discussed. The proposed topology is suitable for the POL （point of load） converters in the highly efficient next generation DC distribution system for data centers.

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.