Voltage Transfer Function Research Articles

Voltage-Gain Design and Efficiency Optimization of Series/Series-Parallel Inductive Power Transfer System Considering Misalignment Issue

Compensation is key to an inductive power transfer (IPT) system in terms of voltage transfer function and efficiency optimization. Basic compensation is simple, but not suitable, for the achievement of variable load-independent voltage-gains without changing the design of the loosely-coupled transformer (LCT). On the other hand, higher-order compensation circuits enable greater design freedom to achieve variable load-independent voltage-gains while keeping the LCT unchanged, but it requires a variety of compensation components, especially the inductive components, which incur significant copper and core losses. This paper proposes a comprehensive design of the series/series-parallel (S/SP) IPT system. The design methodology for variable load-independent voltage-gains is studied to keep the LCT unchanged and achieve zero phase angle input over the whole load range. Design consideration includes the effect of misalignment issue on the voltage-gain and, thus, a design criteria can be derived to ensure an acceptable sensitivity to the misalignment when taking efficiency optimization. The experimental results are presented for verification.

Power management using robust control strategy in hybrid microgrid for both grid-connected and islanding modes

This paper synthesizes input-output feedback linearization (IOFL) and sliding mode controller (SMC) for a hybrid AC/DC microgrid system under both load variations and parameter uncertainties. The controller is indeed aimed to provide an optimal coordinated performance strategy for power electronic converters in both grid-connected and islanding operating conditions for the power management of the hybrid microgrid. The operation of two DC/AC converters in the hybrid microgrid is enriched through the dynamic model completion and the control ability promotion in the islanding mode. The initial control functions for power electronic converters are firstly shaped based on applying the IOFL basics to a comprehensive dynamic model. To reach robustness feature for the controller, the sliding surfaces based on the current errors of the power converters are presented. Then, based on the DC-link voltage transfer functions, it is comprehensively evaluated how much the compensators and sliding coefficients can impact the stability margin and tracking capability of the proposed control functions. In addition, to further investigation, several cost functions are attained through the second-order responses of DC-link voltage to obtain optimal values for the controller coefficients. Simulation results in the MATLAB/SIMULINK environment are employed to show the validity of the proposed control technique under load variations, parameters uncertainty and controller coefficients alteration. Also, some comparative simulation results are attained for verifying the superiority of the proposed control technique.

Circuit Modeling and Signal Transmission Analysis of Inductive Coupler in Wired Drill Pipe

The telemetry drill string transmits the measured drilling and formation parameters near the bit to the ground at high speed through the transmission line in the wired drill pipe and the inductive coupler formed by the coil embedded in the drill pipe joint. The voltage transfer function of the inductive coupler seriously affects the signal transmission characteristics of the telemetry drill string. Present research methods cannot accurately and quantitatively describe the influence of the electromagnetic parameters of the inductive coupler on its voltage transfer function. This paper quantitatively analyzes the effects of the electromagnetic parameters of the inductive coupler on signal transmission through reasonable high-frequency circuit modeling. The generation mechanism of eddy current in the magnetic core and the interaction mechanism between eddy current and coupling coils are studied using the electromagnetic detection analysis method of nondestructive testing (NDT) technology. Then, the high-frequency circuit model of the coupler containing eddy current loss is established. The mathematical model of input impedance and signal transmission characteristics of the inductive coupler is established through circuit analysis. The influence of the electromagnetic parameters of the magnetic core and the load resistance of the coupler on the voltage transmission characteristics and power transmission characteristics of the coupler is studied. The research results show that the relative permeability of the magnetic core, load resistance of the coupler, and signal frequency seriously affect the signal voltage transmission. When the relative permeability of the magnetic core material reaches 50, the voltage transmission of the inductive coupler is effectively improved. The electromagnetic simulation results are consistent with the theoretical analysis of the circuit model, which proves the correctness of the circuit model. This paper provides theoretical guidance for the electromagnetic design of inductive couplers and the improvement of signal transmission characteristics of telemetry drill string.

Magnetic background field-tolerant SQIF-based current sensors

We report on the development of magnetic background field-tolerant superconducting quantum interference filter (SQIF) based on low-capacitance sub-micrometer sized cross-type Josephson junctions either as current sensing amplifiers—even on chip—for advanced superconducting quantum interference device (SQUID) readout circuits or as magnetic field sensor in flux transformer configuration especially for geophysical measurement systems. Their very small parasitic magnetic sensitive areas enable them to operate in the Earth magnetic field and allow for magnetically unshielded cool-down. The careful consideration of magnetic sensitive areas inside each SQUID in the SQIF in all three dimensions result in developed SQIFs with 28 SQUIDs in series exhibiting large voltage swing and transfer function of more than 2 mV and , respectively. We report on the electrical parameters and field stability as well as on the noise performance of the devices under investigation. SQIFs and devices with additional on-chip flux-transformers show input referred current noise levels of and , respectively. We furthermore demonstrate their potential as SQIF-based magnetometers using them in addition with thin-film pickup loops resulting in a white magnetic field noise of . The implemented SQIFs are thus highly compatible with state-of-the-art single SQUID-devices offering beneficial features such as a unique working point, making them excellent suited for implementation of e.g. geophysical instruments.

Modeling and Simulation of PGSPAD-Based Silicon Photomultipliers

This article presents and develops a novel comprehensive simulation model for perimeter gated single-photon avalanche diode-based silicon photomultipliers (PGSPAD SiPMs). A PGSPAD is a modification of single-photon avalanche diodes (SPADs) that contains a third terminal to mitigate perimeter edge breakdown. It does this without excessively enlarging the device area. The applied gate voltage modulates the dynamic range, breakdown voltage, and dark current characteristics. The proposed PGSPAD SiPM model correctly mimics the current–voltage transfer function and the avalanche-quench process of the SiPM detector and is verified by the experimental measurements of a PGSPAD SiPM fabricated in a commercial 0.5- $\mu \text{m}$ CMOS process. The model includes the dark current of the PGSPAD device. This was not included in previous SiPM models. The effect of the number of triggered microcells versus the total number of microcells and the impact of different parameters on the PGSPAD SiPM performance with added gate terminal are evaluated. The photon–electron spectrum with the effect of an extra gate terminal has been studied. Simulation results show very good agreement with experimental measurements.

Analysis and Controller Design for Positive Output Boost Converter With Low Current Stress on Output Capacitor

A nonisolated positive output fifth-order dc-dc boost converter is proposed in this article. This topology is developed from the existing fourth-order boost converter (FOBC) by appropriately inserting a charge-pump cell. Compared to FOBC, the proposed topology offers enhanced voltage gain with reduced switch voltage stress. The proposed converter has an advantage of continuous output-port current over existing boost topologies, which reduces the output capacitor current stress. The voltage conversion ratio and L-C design equations in terms of their ripple quantities are formulated by time-domain analysis. Thereafter, a summary of comparison between the proposed converter and existing boost topologies is presented. The duty-to-output voltage transfer function obtained through the average state-space model shows minimum phase behavior. A PID type voltage-mode controller is designed using the dominant pole placement technique to ensure predefined time-domain specifications along with sufficient dominance factor. Maximum sensitivity (M <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">s</sub> ) is adopted as a measure to ensure the required robustness of the closed-loop system. The analysis and voltage-mode controller design are verified through experimental results. The dynamic performance and robustness of the closed-loop system tested experimentally are in agreement with the desired requirements.

Определение коэффициентов затухания по измеренным частотным характеристикам обмоток силовых трансформаторов. Ч. 2. Анализ результатов измерений

In the first part of the article, based on the results of theoretical studies performed for a simplified transformer winding equivalent scheme, it was shown that the damping factors can be estimated from the width of the resonant peaks of the frequency responses of the module and the reactive component of the voltage at the midpoint of the equivalent scheme, as well as the active component of the input admittance and neutral current of the considered resonant scheme. In this part of the article, the practical possibility of applying the obtained theoretical relations between the damping factors and the width of resonant peaks in relation to the frequency responses of power transformer windings is considered. The results of calculations of the damping factors at the two power transformers made by using the fitting of the free component of transient voltage and by determining the width of the resonance peaks of the active component of winding neutral current and the voltage transfer function, corresponding to intermediate points of the winding. It is shown that the evaluation of the values of the winding damping factors can be performed as a byproduct of transformer condition assessment by frequency response analysis (FRA).

Design and Synthesis of Inductorless Passive Cell Operating as Stop-Band Negative Group Delay Function

This paper develops an original circuit theory of unfamiliar stop-band (SB) negative group delay (NGD) topology. The proposed NGD topology is implemented without inductor component. The developed theory is established with passive cell constituted by RC-network based high-pass (HP) and low-pass (LP) NGD composite circuits. The analytical investigation of the SB-NGD circuit is introduced from the elaboration of voltage transfer function (VTF). The canonical form enabling to identify SB-NGD circuit is analytically expressed. The different SB-NGD characteristics as GD value, and, center and cut-off frequencies are innovatively formulated in function of the circuit resistor and capacitor components. The existence condition of SB-NGD function is also established. The inductorless SB-NGD topology is validated by a proof-of-concept (POC) circuit implemented by surface-mounted-device (SMD) component based printed circuit board (PCB). The measured VTF magnitude and group delay (GD) are extracted from the experimented S-parameters. A good agreement between the calculated, simulated and measured results is obtained. The SB-NGD behavior has measured center frequency of about 32 MHz. The lower- and upper-NGD cut-off frequencies are about 9.15 MHz and 98.3 MHz. The optimal NGD values at low and higher frequencies are −3.25 ns and −56 ps.

Определение коэффициентов затухания по измеренным частотным характеристикам обмоток силовых трансформаторов. Ч. 1. Теоретическое рассмотрение

To model high-frequency processes and determine the stresses on the internal insulation of transformer windings, reliable high-frequency models of power transformers are required. The accuracy of modeling high-frequency resonance processes in the windings depends on how correctly the model reproduces the natural frequencies and damping of free oscillations in the windings. To construct and verify high-frequency models of power transformers, it is necessary to have experimentally obtained data on the values of damping factors. There is a known method for determining the winding damping factors based on measurements of the voltage transfer functions at the internal points of the windings and their subsequent processing using the vector fitting technique, but its application is not always possible in practice. The article presents the results of theoretical studies performed for a simplified transformer winding equivalent circuit. It is shown that the damping factors can be estimated from the width of the resonance peaks of the frequency responses of the voltage modulus and reactive component at the midpoint of the equivalent circuit, and from the input admittance resistive component and current in the neutral of the considered resonance circuit.

CFA BASED UNIVERSAL BIQUAD FILTER

This paper is a review of the organizational structure and challenges that a technological enterprise faces during scaling, from the perspective of the engineering management. After expanding operations internationally, the distributed engineering teams developing hardware and software for internet of things applications, face issues regarding culture, communication, leadership, project planning and management. Relevant literature addressing these issues is presented. We elaborate on already implemented measures for improving the overall efficiency and propose further processes introduced in recent literature that can be beneficial for further optimizing the new product development. Potential knock-on effects by such implementation are also discussed. A universal biquad filter using current feedback amplifiers (CFA) as active devices and a canonical number of capacitors is presented. It realizes the classical feedforward structure through the use of grounded capacitors and MOS transistors, which permit a full integrability. The proposed circuit has attractive characteristics, as the possibility to electronically control the transfer function coefficients and the possibility to be directly inserted within cascaded configurations. The theoretical analysis of the circuit is followed by some PSPICE simulation results in agreement with the theoretical findings. In this paper a universal fully integrable biquad using CFAs as active devices and a canonical number of capacitors is presented. It realizes the classical feedforward structure [3] through the use of grounded capacitors and MOS transistors. The presence of grounded capacitors makes the proposed circuit absorb shunt parasitic capacitances. All the possible kinds of responses can be realized, while in the biquad reported in [2] only the low-pass and band-pass responses can be obtained. The numerator and denominator coefficients of the voltage transfer function of the proposed biquad can be electronically controlled by acting on the gate voltages of the MOS transistors of the circuit. Moreover the presented structure has a low-impedance output and then it can be cascaded without additional buffers.

Hybrid Tuning of a Boost Converter PI Voltage Compensator by Means of the Genetic Algorithm and the D-Decomposition

In this paper the D-decomposition technique is investigated as a source of non-linear boundaries used with the Genetic Algorithm (GA) search of a PI voltage compensator gains of the boost converter operating in Continuous Conduction Mode (CCM). The well known and appreciated boost converter has been chosen as a test object due to its right-half plane zero in the control-to-output (c2o) voltage transfer function. The D-decomposition, as a technique relying on the frequency sweeping, clearly indicates not only the global stability but, in its extended version, regions satisfying the required gain (GM) and phase (PM) margins. Such results are in form of easy to interpret functions KI=f(KP). The functions are easy to convert to the GA constraints. The GA search, with three different performance indexes as the fitness functions, is applied to a control structure with time delays basing on identified c2o voltage transfer functions. The identification took place in an experiment and in simulation. Outcomes of the identification are compared to mathematically derived formula taking into account certain parasitics. A complete set of practically useful mathematical formulas together with their validation in simulation and experiment is included.

Bandwidth and Detection Sensitivity Analysis of Integrated Capacitive PD Sensors for Pre-Molded Cable Joints

This contribution evaluates integrated capacitive PD sensors for pre-molded cable joints, which can be used for PD online monitoring systems. In order to quantify differences in bandwidth and detection sensitivity, an analysis of the voltage transfer function of such sensors is given. Therefore, several sensor versions and their parameters are considered. Furthermore, a SPICE model is presented, which models the sensor behavior in frequency domain and can be used to estimate the transfer function. Finally, the sensor function is evaluated in the time domain, using a broadband UHF signal.

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.

Small-Signal Modeling of Open-Loop PWM Tapped-Inductor Buck DC–DC Converter in CCM

A tapped-inductor buck dc-dc converter uses the tapped-inductor to further step-down the output voltage. This article presents a small-signal model of a tapped-inductor buck dc-dc converter by using the circuit averaging technique. The obtained nonlinear model is linearized to derive its linear large-signal, small-signal, and dc models. The small-signal model is then used to derive open-loop transfer functions namely, control-to-output voltage transfer function and the input-to-output voltage transfer function. MATLAB was used to obtain their respective Bode plots and later validated experimentally using a gain-phase network analyzer.

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.

Impedance matching and efficiency improvement of a dual-band wireless power transfer system using variable inductance and coupling method

This paper proposes a dual-band wireless power transfer (DWPT) system which can deliver more power compared to a single-band WPT within the electromagnetic field constraints. Moreover, one of its channels can be applied to increase the data transfer rate compared to a single-band WPT. In this work because of less crosstalk between distinct frequencies, a dual-resonant single-coil is used similarly as a transmitter and receiver. The main challenge in the design of conventional DWPT systems is the simultaneous impedance matching at the different resonant frequencies. In the proposed method, this problem has been solved by varying the coupling factor between the source (load) and the dual-band internal resonator. Moreover, we analytically investigate the influence of the different values of the source(load) inductance on impedance matching. The system equivalent circuit model is presented, and the voltage transfer function and the matching condition for transmitting maximum power are extracted. To evaluate the system performance, the power transfer efficiency is simulated by HFSS software and validated by experimental results. The measurement results show the efficiency of 71% and 56% at frequencies of 6.78 MHz and 13.56 MHz, respectively.

Design and voltage regulation of inductively coupled wireless power transfer circuits with an intermediate coil

An inductively coupled wireless power transfer (WPT) circuit consisting of the transmitter, the receiver, and an additional intermediate coil is studied. It is assumed that the intermediate coil is located coplanar with the transmitter coil. Although it has been known that the intermediate coil serves as a power repeater, its effect on the three-coil WPT circuit characteristics has not been thoroughly investigated. Accordingly, this study analyses how the intermediate coil affects the voltage transfer function and the input impedance of the WPT circuit. Based on the analysis result, design considerations are presented and output voltage regulation via operation frequency adjustment is discussed. A design example for the three-coil WPT circuit is presented and the simulation and experimental results are provided.

TOIL and damped-SOGI control of quasi-Z-source inverter based grid-connected renewable-system

A strategy is proposed in this paper to indirectly control the peak dc-link voltage of quasi-Z-source (qZS) inverter fed grid-connected renewable-system by sensing the voltages of qZS network capacitors. The ac- and dc-sides are modeled separately and the crossover frequency of ac-side control loop is kept high to avoid clashes with the dc-side. A third-order-integral-lead (TOIL) controller is realized to regulate peak dc-link voltage and minimize the non-minimum phase characteristic effect of shoot-through duty-ratio to peak dc-link voltage transfer function. A damped-second-order-generalized-integrator (SOGI) offering high power frequency gain is used to control the ac-side current and attain zero steady-state error. The effect of time-delay in control is also analyzed. The performance of the proposed TOIL and damped-SOGI controllers is compared with other designed linear and sliding mode controllers. The system is investigated using MATLAB/Simulink and validated through hardware-in-the-loop (HIL) real-time simulations in OPAL-RT.