Output Voltage Transfer Research Articles

Tri-State Coupled Inductor Based High Step-Up Gain Converter Without Right Hand Plane Zero

This brief proposes a novel tri-state Coupled Inductor (CI) based high step-up gain converter without Right Half Plane (RHP) zero. The basic Coupled Inductor based Boost Converter (CIBC) can achieve high step-up gain by changing the turn ratio of CI and duty cycle. However, the control to output voltage transfer function of basic CIBC converter in CCM has RHP zero hence non-minimum phase behavior with limited bandwidth and unstable operation of the converter when step changes in duty cycle. RHP zero can be eliminated from the basic CIBC by providing freewheeling period in converter operation hence additional degree of freedom to control energy transfer to output capacitor. Thus, the converter achieves stable operation and improves the bandwidth. The small-signal model of the proposed converter is derived to verify the claim. All theoretical findings are verified by experimental results. Experimental results are provided from implemented laboratory prototype of input voltage of 24 V to output voltage of 100 V and 200 W power.

A dynamic supercritical carbon dioxide foaming method for fabricating wrinkled surface to enhance triboelectric nanogenerator performance

AbstractTriboelectric nanogenerator (TENG) is a promising energy harvester to overcome the energy depletion issue. The surface structure has been considered as an effective way to enhance the triboelectric performance. Herein, a dynamic supercritical carbon dioxide (scCO2) foaming method, which introduced a scCO2 flow field during scCO2 saturation, was proposed to fabricate thermoplastic polyurethane (TPU) foams with surface wrinkly structures. The size of the surface wrinkles could be regulated in the range of 1.8–10 μm by varying the foaming pressure. The surface wrinkled TPU film with wrinkle wave length of 2.4 μm demonstrated an excellent enhancement in output voltage (130%), current (180%), and maximum transfer charge (130%) when paired with surface structured polydimethylsiloxane film in a TENG. Due to the excellent durability and flexibility of the composing materials, the developed TENG showed outstanding stability in long‐term continuous operation. With a high power density of 0.5 W/m2 achieved on a 107 Ω external load, the flexible TENG could be used to charge capacitors, power light‐emitting‐diodes, and served as a self‐powered sensor to detect various human movement behaviors. This work provides a new path for the fabrication of surface wrinkled films for the sustainable development of high performance TENGs.

Stability Prediction of Integrated-Circuit Based Constant ON-Time Controlled Buck Converters

The commonly used average model is not applicable to predict the stability performances of constant <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> -time (COT) controlled buck converters. It has been reported that the issues of stability can be addressed by using the control signal to output voltage transfer function of the converters, named <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> , for such class of converters. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> can be mathematically derived using describing-function approach to include the effects of side-band harmonics of the pulsewidth modulation (PWM) modulator. This is essential for modeling the control behavior of the COT converter class. However, the actual <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> can deviate significantly from the derived ideal model. Therefore, a measured <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> transfer function is important for real-world stability predictions. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> measurement, however, is often not feasible because the points of measurements are physically inaccessible due to integrated control circuit implementation. In this article, a realistic <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> extraction method is proposed for each of the four commonly used COT schemes. Based on the measured <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">G</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">VC</sub> , a procedure to predict the stability boundary is proposed and verified.

Design issues and performance analysis of CCM boost converters with RHP zero mitigation via inductor current sensing

The right-half plane (RHP) zero in the control to output voltage transfer function of a boost converter operating in the continuous conduction mode limits the loop bandwidth. By injecting a scaled version of the inductor current into the loop, it is possible to shift the zero from the right-half plane to the left-half plane, which leads to increased stability of the control loop. This solution generates a static voltage error at the output of the converter (tracking error), which may be unacceptable in practical applications. A few strategies to mitigate or correct this tracking error have been suggested. However, they have never been fully assessed. This paper thoroughly investigates the impact of the RHP zero mitigation technique on the dynamic performance of a boost converter, and identifies the complex trade-off between the system stability, transient response, and tracking error correction capability. Based on these findings, design guidelines are provided to help maximize system performance. A representative case study is considered to highlight the performance benefits and simulation results are presented to validate the analysis.

A Minimum-Phase Dual Output Hybrid Converter for Standalone Hybrid AC/DC Supply Systems

A minimum-phase dual output hybrid converter for standalone hybrid ac/dc supply systems is proposed in this article. Due to its circuit arrangement, the converter eliminates the right half-plane zero from the control-to-dc output voltage transfer function (i.e., making the system minimum-phase) and gives simultaneous ac and dc outputs using single-stage power conversion. Due to the minimum-phase behavior, the converter is capable of operating at a high load current while maintaining closed-loop stability. Further, it enables simpler controller design and faster dynamic response. As it has two inductors, one at the main input voltage terminals and another at the output dc voltage terminals, it gives continuous input/output currents. Also, it gives step-down/step-up dc output voltages along with the step-down ac output voltage based on the duty ratio. It also has inherent shoot-through protection capability, which results in reliable power conversion on the occurrence of misgating of the switches caused by electromagnetic interference. A hybrid pulsewidth modulation scheme is developed to achieve simultaneous ac and dc outputs. Detailed mathematical modeling is carried out to demonstrate the properties of the converter, and its experimental validation is done through a laboratory prototype. Moreover, at different loading conditions, efficiencies of the converter are measured for varying dc load (having constant ac load) and varying ac load (having constant dc load), to show its effectiveness.

A high-performance transparent and flexible triboelectric nanogenerator based on hydrophobic composite films

The modern portable and wearable electronic devices have been put forward a claim on flexibility, transparency and lightweight. Triboelectric nanogenerator (TENG) has attracted great attention as basic component of independent power source due to its outstanding characteristics. Here, a simple and efficient approach was demonstrated to modify poly-(dimethylsiloxane) (PDMS) in order to both improve the output electrical performance of TENG and optimize its hydrophobility as well. The 4 cm2 TENG consisting of PDMS-perfluorododecyl trichlorosilane (FDTS) friction layer and copper nanowires (Cu NWs)/reduced graphene oxide (RGO) electrode, exhibits high output voltage and large transfer charge quantity of 125 V and 80 nC, where the corresponding electrical performances are larger with several times than that of pristine PDMS-based TENG. A voltage of 105.8V can be obtained even under the ambient condition with high humidity of ~60%. The improvements are attributed to the reaction between FDTS and PDMS, introducing fluorine element to absorb more electrons and increasing dielectric constant. Moreover, the fabricated TENG remains high visible transmittance (70.1%) and good flexibility as energy sources which can satisfy the demands of portable and wearable electronic devices.

Tepe Akım Kontrol Modunda Çalışan SEPIC DA/DA Dönüştürücünün Tam Çözümlü Sembolik Zayıf Sinyal Analizi

Full order small signal analysis of peak-current controlled non-isolated Single Ended Primary Inductor Converter (SEPIC) is presented by utilizing pwm-switch model in Continuous Conduction Mode (CCM). The analysis provides control to output voltage transfer function together with its zeros and poles in symbolic form taking into account parasitic resistances of all four reactive components in the SEPIC topology. The resultant transfer function is with 4th order numerator and 5th order denominator, which necessitates approximation in deriving formulas of zeros and poles in symbolic form. Symbolically derived transfer function of the SEPIC is validated on two different numerical examples, one with operating in step down mode and another operating in step up mode, by frequency domain PSpice simulations on average circuit models and by time domain LTspice simulations on switching models. The mathematical analysis, PSpice and LTspice simulations, and measurement results of control to output voltage transfer function of SEPIC agree very well proving that the symbolic control to output voltage transfer function of SEPIC together with its zeros and poles are successfully derived.

Optimization of efficiency for power system using three phase AC to AC matrix converter with the algorithm of fuzzy controller

This paper suggested a new contribution of three phase AC to AC matrix converter MC via fuzzy logic controller FLC to enhance the whole system. However, the weakness of matrix converter is that the input- output voltage transfer is control to 87% for input and output waveform. Also, matrix converter is more sensitive to the trouble of input voltage which deteriorates the system performance. To overcome these problems, and to improve the efficiency of system, FLC with matrix converter is proposed to minimize the sensitivity to the load, and to increase voltage transfer. In this paper the currents a,b,c are converted to alpha and beta current via Clarke transformation . In this method two FLC are used. The error (between alpha current and reference current) (e) and the change of this error (de) will apply to first FLC. The output of FLC is actual alpha current. In the other hand, the error of beta current and the change of error are also passes through the second FLC to produce the actual beta current. The actual alpha and beta current is converted to direct and quadrature d-q current by park transformation. The d-q current is converted to (a, b, c) out currents by inverse park transformation, the results of this method express that the matrix converter with FLC is more capable, high accuracy with better efficiency as compared with conventional matrix converter system.

Optimization of efficiency for power system using three phase AC to AC matrix converter with the algorithm of fuzzy controller

This paper suggested a new contribution of three phase AC to AC matrix converter MC via fuzzy logic controller FLC to enhance the whole system. However, the weakness of matrix converter is that the input- output voltage transfer is control to 87% for input and output waveform. Also, matrix converter is more sensitive to the trouble of input voltage which deteriorates the system performance. To overcome these problems, and to improve the efficiency of system, FLC with matrix converter is proposed to minimize the sensitivity to the load, and to increase voltage transfer. In this paper the currents a,b,c are converted to alpha and beta current via Clarke transformation . In this method two FLC are used. The error (between alpha current and reference current) (e) and the change of this error (de) will apply to first FLC. The output of FLC is actual alpha current. In the other hand, the error of beta current and the change of error are also passes through the second FLC to produce the actual beta current. The actual alpha and beta current is converted to direct and quadrature d-q current by park transformation. The d-q current is converted to (a, b, c) out currents by inverse park transformation, the results of this method express that the matrix converter with FLC is more capable, high accuracy with better efficiency as compared with conventional matrix converter system.

Differential evolution‐based pulse‐width modulation technique for multiphase MC

This paper addresses multiphase matrix converter (MPMCs) modulated with Venturini's classical scalar approach. The solution to obtain time-varying modulation functions was limited to configuration, which was later extended to configuration. The equations had four constants that were common to all modulation functions; out of which two were defined arbitrarily and other two were found analytically by reducing the equation to a two-variable optimisation problem. However, in this work, an attempt is made to provide flexibility in finding other solutions by taking all the constants as variables. Thus, Differential Evolution (DE) algorithm is adopted in the proposed modulation approach to solve the complex equations thus obtained. Another aim is to find the solution for the MPMC, where inputs are more than three. It is found that the optimal solutions exist only for configuration and are in close approximation with the results of analytical approach. Other solutions were found for certain input and output frequencies and voltage transfer ratios whose results are discussed. It is also found that the solution does not exist for configurations with input phases are other than three. The discussion is supported by simulation and experimental results on a matrix converter at various values of voltage transfer ratios and input/output frequencies.

High‐Performance Transparent and Flexible Triboelectric Nanogenerators Based on PDMS‐PTFE Composite Films

AbstractPoly(dimethylsiloxane) (PDMS) is commonly used as the negative friction layer of triboelectric nanogenerator (TENG) which can harvest ubiquitous mechanical energy. However, it is essential to improve the energy output of PDMS‐based TENGs with high visible transmittance for transparent flexible TENG. In this study, a simple, cost‐effective and efficient approach is demonstrated to modify PDMS without degrading high transparency. The novel flexible TENG based on PDMS‐PTFE composite film exhibits high output voltage and large transfer charge quantity of 95 V and 85 nC respectively, which are enhanced more than threefold in the output compared with pristine PDMS‐based TENG. And the TENG device generates average power output of 3.0 W m−2 across the matched optimal load resistance. The enhancement is attributed to PTFE particles dispersed in PDMS matrix, which can increase surface potential and reduce work function. Moreover, the TENG device also remains good transparency and flexibility, which satisfies the demands of transparent and flexible electronic devices. The proposed PDMS/PTFE based TENG shows good application prospects for various power sensors and even wearable energy suppliers.

Design of a novel receiving structure for wireless power transfer with the enhancement of magnetic coupling

In a wireless power transfer (WPT) system, the transfer performance is related to the mutual inductance between coils. However, the mutual inductance decreases with the increase of transfer distance. In this work, the relationship between the output voltage and the mutual inductance for WPT systems with air core and with ferrite core are analyzed. In order to improve the mutual inductance, a novel configuration of receiving resonator with a strong magnetic coupling is proposed. The mutual inductance and magnetic field distribution for coils with a cylindrical core and with the novel configuration are compared. Experiments are carried out for validation. The results indicate that the proposed WPT system is superior to the system with the cylindrical ferrite core in increasing the output voltage and power transfer efficiency.

Tepe Akım Kontrol Modunda Çalışan Flyback Dönüştürücünün Küçük Sinyal Ses Duyarlılık Analizi

Small signal audio susceptibility of flyback converter with peak current mode control method is presented by utilizing pwm-switch model in Continuous Conduction Mode (CCM). The analysis provides input voltage to output voltage transfer function together with its zeros and poles in symbolic form. Numerator and denominator of the resultant transfer function are both 3rd order. While symbolic equations of zeros are provided as exact solutions, the symbolic equations of poles are provided as approximate solutions with the assumption that the real pole is well separated from the resonant frequency of the complex pole pair. Symbolically derived transfer function of flyback converter is validated on a numerical example by time domain PSIM simulations on a switching flyback converter model. The mathematical analysis and PSIM simulations of input voltage to output voltage transfer function of the converter agree very well up to frequencies below half the switching frequency.

Mitigation of Positive Zero Effect on Nonminimum Phase Boost DC–DC Converters in CCM

The control loop stability in boost converters operating in continuous conduction mode has been restricted due to its nonminimum phase nature: the presence of a positive zero (right-half plane zero) in the control to output voltage transfer function. This paper proposes a method to mitigate the effect of the zero on the control loop by shifting the position of the zero to the left-half plane and hence leading to increased stability for the control loop of the boost converter. Superior performance of the proposed method has been clearly demonstrated using simulation and experimental results.

Appropriate compensation method for ensuring stable output voltage and maximum transfer efficiency for wireless power transfer

Appropriate compensation method for ensuring stable output voltage and maximum transfer efficiency for wireless power transfer

Small Signal Modeling of a DC-DC Type Double Boost Converter Integrated With SEPIC Converter Using State Space Averaging Approach

This study presents a detailed small signal analysis of a DC-DC type double boost converter integrated with SEPIC converter. The integrated converter has the features of the conventional boost and SEPIC converters, such as continuous input current, low input current ripple with extended step up capability. The converter consists of seven dynamic elements and hence it would be interesting to study the small-signal model of the converter. State-space averaging technique is used to derive the small signal model. The duty ratio control to output voltage transfer function is derived. A 50W prototype of the integrated double boost SEPIC converter is implemented using PIC 16F887 microcontroller, operating in continuous conduction mode. The measured results on the prototype verify the theoretical analysis.

Tepe akım modu kontrollü Zeta dönüştürücünün küçük işaret analizi

In this study, small signal analysis of peak current-mode controlled, non-isolated Zeta converter is presented. The PWM-switch model in Continuous Conduction Mode (CCM) is utilized in the analysis. The control to output voltage transfer function is derived in symbolic form including the esr of the output capacitor. The exact zeros of the transfer function are given in symbolic form. However, the peak current-mode PWM-switch model yields 5 th order polynomial in its denominator, which necessitates approximate root analysis in finding the symbolic equations of its poles and quality factors. By using this analysis, the approximate poles and quality factors also derived symbolically in the paper. *

Research on Linear Output Voltage Transfer Ratio for Ultrasparse Matrix Converter

Many existing research works of ultrasparse matrix converter (USMC) show that the maximum linear output voltage transfer ratio (MLO-VTR) is less than 0.866, however, this paper proves that based on space vector modulation, MLO-VTR for USMC can break the ultimate value. First, based on the condition that input power factor is one, the maximum output voltage within one carrier period and the maximum linear output voltage are derived. Further, the mathematical equations among MLO-VTR, the output/input frequency ratios, and the output voltage initial phase are also derived. After that, by solving the operating limits of the mathematical relationship of the MLO-VTR, we can obtain the maximum value of MLO-VTR under different output/input frequency ratios which can be more than 0.866. Finally, all of theoretical derivations are verified by experiments.

Hysteretic Transition Method for Avoiding the Dead-Zone Effect and Subharmonics in a Noninverting Buck–Boost Converter

A new hysteresis window method is proposed as a solution for avoiding the operational dead zone that exists at the transition between buck and boost operating modes in all noninverting buck-boost converters. In addition, this method also eliminates the discontinuities in the converter's steady-state output voltage transfer characteristic, which is a function of the duty cycle. The converter's output voltage function is surjective and, therefore, smooth mode transitions are achieved. The negative effects of operating within the dead zone are shown by the presence of subharmonics in the output voltage, increased output voltage ripple, poor regulation, and the instability of the converter during the transition between buck and boost operating modes. The dead-zone avoidance technique proposed in this paper eliminates all these issues while at the same time ensures highly efficient operation of the converter. An additional advantage of the technique is its simplicity, which allows for implementation into low-cost digital signal controllers, as well as into analog control circuits. The advantageous features of the proposed approach were evaluated on the basis of comparisons with three other dead-zone avoidance approaches and the initial case, which does not utilize any dead-zone avoidance technique. All the experiments were carried out on a purpose-built prototype of a noninverting buck-boost converter with magnetically coupled inductors.

Research on input‐voltage feedforward control for high‐order converter topologies

The input-voltage feedforward control for the high-order converter is researched in this study. Input-voltage feedforward control can significantly reduce the audio susceptibility, that is, the input voltage to output voltage transfer function of DC–DC converter. The unified feedforward controller forms in different control modes have been derived. If the converter's model is a high-order model, its desired feedforward controller to eliminate audio susceptibility is complex. In this study, a decomposition block diagram for high-order controller is given so the complex controller can be realised by the composition of simple controllers. When the desired controller is impossible for realisation, its proportional form can be applied to the converter to decrease the audio susceptibility in the low-frequency range. The effective frequency range is related to the main circuit parameters of the converter. The conclusions have been verified by simulation and experiment results.