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This paper is concerned with control-oriented modeling of a class of wireless power transfer systems with a phase-shift-controlled inverter. Two methods are investigated: the analytical modeling method, which is based on physical laws, and the refined instrumental variable method, which is based on sampled data. It shows that the former provides physical insights into the system, and that the resulting models will be accurate if the true circuit component parameters are a priori known. Otherwise, the model accuracy may decline. By contrast, the latter provides a cheap solution for accurate modeling, based only on a set of sampled input–output data, and the resulting model can capture very well the dynamic behavior of the system within a defined operating range. In real applications, it is always hard to know the actual circuit component parameters, since they may drift from the nominal values, due to some reasons such as the aging of circuit components and the variation of coil placement, making the analytical modeling method not very accurate. Therefore, to preserve the virtues of both methods, it is suggested to use them as a combination, that is, using the analytical modeling method to determine the model structure while using the data-driven modeling method to estimate the model parameters. All results derived in this paper are verified by means of both numerical simulation and experimental validation. [ABSTRACT FROM AUTHOR]

This paper introduces a novel modeling approach that allows to obtain fast simulations of pulsewidth-modulated dc–dc switched-mode power supplies (SMPS). The proposed methodology combines the use of precise switched models during transient evolutions and averaged models during steady-state or slowly varying conditions. In that way, the resulting mixed modeling approach enables to obtain the detailed switching behavior of SMPS in the context of long-term simulations. The commutation between models is automatically performed in runtime by an algorithm that detects the transient or slowly varying condition according to the evolution of some model variables. When the precise switched model is used, the mentioned algorithm also adjusts the averaged model parameters so that its results are accurate irrespective of the operating point. This paper also describes the implementation of the methodology in the Modelica language and reports simulation experiments showing that the results are as accurate as those obtained using precise switched models, but several times faster. [ABSTRACT FROM AUTHOR]

This paper presents a unified physics-based insulated-gate bipolar transistor (IGBT) compact model for circuit simulation that predicts the performance of both Si and SiC, n- and p-channel devices. The model can predict the detailed switching waveforms of these technologies based on its charge-based formulation. Further, this compact IGBT model is presented alongside a unique datasheet-driven parameter extraction process. The parameter extraction process enables users to quickly extract model parameters from data typically published without the need of taking physical measurements. The model has been validated with both Si and SiC devices for static and dynamic characteristics. The SiC IGBTs used for validation are a 12.5-kV n-channel device and a 13-kV p-channel device, while the Si IGBT chosen was IXDH30N120 from IXYS Corp. (Milpitas, CA, USA). This is the only IGBT model that predicts the performance of both n- and p-channel, Si and SiC devices, providing more freedom for the development of complex power electronics circuit designs. The convergence of the model has been verified by implementing a complex circuit consisting of both a dc–dc converter and a dc–ac inverter. The results presented here show that the unified model can be used to describe the behavior of a wide range of Si and SiC IGBT circuits. This paper is accompanied by a Verilog-A source code and a power point file demonstrating the model parameter extraction sequence. [ABSTRACT FROM AUTHOR]

In this paper, a current controller for a parallel operation of inverters is described. When inverters operate in parallel, it is a well-known fact that the inverter current is composed of the average current (AVC) and the zero-sequence circulating current (henceforth ZSCC), which inevitably flows between inverters under the parallel operation. Considering this, previous studies concentrated on reducing ZSCC. However, in this paper, it is found that the inverter current has another component, a differential current, in addition to the two components of AVC and ZSCC. Based on these three decomposed current components, three equivalent circuits are derived from n-paralleled inverters. To minimize the differential current and improve the regulation performance of the total output phase current, a decomposed current control scheme is proposed from equivalent circuit models. The proposed algorithm is applied to a system consisting of three paralleled two-level inverters with small shared inductance whose dc links are connected in common. Additionally, synchronous pulsewidth modulation is employed as the PWM method for each inverter. The proposed current controller is compared with two conventional current controllers, one where each inverter controls its own currents and the other where only AVC is controlled. Through experiments, it is shown that these conventional controllers have limitations and the proposed current controller overcomes these limitations. The effectiveness and feasibility of the proposed control scheme are verified through experimental results. Especially, both theoretical analysis and experiment results verify that the proposed method is robust with regard to parameter errors. [ABSTRACT FROM AUTHOR]

System identification is fundamental in many recent state-of-the-art developments in power electronic such as modeling, parameter tracking, estimation, self-tuning and adaptive control, health monitoring, and fault detection. Therefore, this paper presents a comprehensive review of parametric, non-parametric, and dual hybrid system identification for dc–dc switch mode power converter (SMPC) applications. The paper outlines the key challenges inherent with system identification for power electronic applications; speed of estimation, computational complexity, estimation accuracy, tracking capability, and robustness to disturbances and time-varying systems. Based on the literature in the field, modern solutions to these challenges are discussed in detail. Furthermore, this paper reviews and discusses the various applications of system identification for SMPCs; including health monitoring and fault detection. [ABSTRACT FROM AUTHOR]

A non-segmented PSpice model of silicon carbide metal-oxide semiconductor field effect transistor (SiC mosfet) with temperature-dependent parameters is proposed in this paper, which can improve the model's convergence and temperature characteristics. The non-segmented equations and the parameter-extraction method for the proposed SiC mosfet PSpice model are introduced first. Simulation and experiment results are given to verify the correctness of the model while considering the temperature-dependent parameters. The static characteristics of the model are verified by comparing the simulation curves with the static characteristic curves in the SiC mosfet's datasheet, and its dynamic characteristics are verified by comparing the simulation results with experimental results under different ambient temperatures (25, 75, and 125 °C) based on a double-pulse test platform. Moreover, the proposed non-segmented model, the conventional segmented model, and the model from the manufacturer are adopted and simulated in a full-bridge inverter. The simulation results show better convergence of the proposed non-segmented model. Therefore, an accurate and practical simulation model of SiC mosfet is provided for circuit design in this paper. [ABSTRACT FROM AUTHOR]

A recent paper by Hoffmann et al. presents a discrete-time model in a rotating $dq$ reference frame of an R-L filter and its current control. The purpose of this note is, first, to show that the discrete model presented in the paper behaves differently to the sampled continuous-time model of the plant, formulated in the stationary $\alpha \beta$ reference frame; second, to find the proper discretization of the plant in $dq$ coordinates; and third, to verify that there is cross coupling between axes $d$ and $q$ in the closed-loop system if the original model is used, and that this coupling is not present when using the model found in this note. In the note, it is verified that having a precise model of the plant allows us to fulfill the control objective of obtaining the complete decoupling between axes. [ABSTRACT FROM AUTHOR]

This paper presents a novel platform for accurate mathematical modeling of the propulsion system of electric cars. It provides, for the first time, a hardware-in-the-loop (HIL) real-time experimental verification case study of a General Motor Chevrolet Volt for power, control systems, and the mechanical systems. The contribution of this paper can be categorized into three approaches: First, each component of the powertrain is accurately modeled taking transient dynamics of all components of the electric vehicle into consideration. Further, a PSIM simulation platform is consequently developed to demonstrate the validity of this mathematical modeling. Finally, the Typhoon HIL is used to provide the experimental verification of the proposed model in real time, which precisely validates the viability of the model. HIL technology is used to prototype and test the proposed control system while simulating the power circuit on the HIL module platform. The permanent magnet synchronous motor and the power electronics hardware components are simulated in real time at which the parameters can be changed during the simulation. However, the control algorithm is generated as a C code and downloaded to the TI controller that exists on a digital signal processing board. The results from the simulation based on PSIM environment and hardware validations using HIL are in agreement, which validates the developed model. The performance has been investigated under different load operating conditions in real time to verify its robustness. The case study can be extended for any electric car as it provides a generic platform for modeling any propulsion system. [ABSTRACT FROM AUTHOR]

This paper presents two novel measurement methods to characterize silicon carbide (SiC) MOSFET devices. The resulting data are utilized to significantly improve the extraction of a custom device model that can now accurately reproduce device switching behavior. First, we consider the $I_{\text{d}}- V_{\text{ds}}$ output characteristics of power devices such as SiC transistors. These are typically measured using traditional curve tracers, but the characterization of the high-voltage and high-current (HVHC) region is very challenging because of device power compliance and self-heating. In this paper, we introduce a measurement technique that overcomes self-heating and derives the HVHC region from switching waveforms. The switching transient characteristics of devices are used to determine drain current $(I_{\text{d}})$ as a function of drain–source voltage $(V_{\text{ds}})$ in the HVHC range. Second, we consider another challenging characterization area: measurement of nonlinear capacitances when device is turned on. These capacitance characteristics of on-state devices are important for correcting disagreements between simulations and measurements in turn-off switching transient waveforms and cannot be measured using a conventional capacitance-voltage meter. We introduce S-parameter measurements as an effective method to obtain the capacitance characteristics of both off-state devices and on-state devices. These novel measurement techniques have been applied to the modeling of a SiC device. The extracted device model, a modified version of the popular Angelov−GaN high-electron-mobility transistor model, shows significant improvement in terms of the accuracy of switching waveforms of devices over a wide range of operating conditions. [ABSTRACT FROM AUTHOR]

This paper proposes a battery simulator (BS) based on a Z-source rectifier (ZSR), with the intention of emulating the discharge or charge characteristic of an actual lithium-polymer battery with high voltage and large capacity. The proposed BS is used for power testing for battery applications. The battery model, combined with a Shepherd model and a Thevenin model, is adopted to freely change the properties and specifications of the battery and to replicate the dynamic behavior of the battery, which is discretized to utilize the digital controller of the BS. The closed-loop voltage controller at the dc side of the ZSR is designed to emulate the rapid dynamic characteristics of the battery based on small-signal methods, considering the influence of the components of the impedance network. In this paper, battery voltage control algorithm (BVCA) is also utilized to minimize the voltage stress across switches while controlling two dc-side voltages within a wide range of output voltages. Simulation and experimental results are provided to verify the BS of the new feature and the proposed control method. [ABSTRACT FROM AUTHOR]

An electrical transient model (ETM) of insulated-gate bipolar transistor (IGBT)-diode switching cell is developed by coupling a temperature-dependent IGBT model with power loss model. The nonlinear behavior of IGBT and the reverse recovery characteristic of the diode are considered in this model to simulate the transient switching waveforms. Based on the transient waveforms of ETM under various operating conditions, the power loss estimation method (PLEM) for IGBT is developed. In addition to traditional modeling techniques that only uses ideal switch, this paper uses the model to replicate the power loss behaviors of semiconductor devices in circuit simulation by looking up tables. The proposed ETM is simulated in PSCAD/EMTDC with nanosecond time step, whereas the overall system application can be simulated with conventional time step in range of microsecond. By this way, the model can promise reasonable accuracy as well as an acceptable fast solving speed. The proposed ETM and PLEM have been implemented in PSCAD/EMTDC simulator and validated by experimental results using a double pulse test bench and boost converter test platform. [ABSTRACT FROM AUTHOR]

Wireless power transfer (WPT) systems in dynamical applications, such as roadway-powered electrical vehicles, require dynamical models for the analysis and control. Conventional modeling methods for WPT systems lead to high-order models as each resonant voltage or current is described by two slowly varying real-valued variables. Other modeling methods may reduce the order but suffer from disadvantages, such as the lack of analytical expressions, loss of generality, and incomplete modeling. This paper develops a systematic and intuitive modeling approach using time-domain dynamic phasors and proposes reduced-order models by applying appropriate s-domain approximations to the linear parts of the system. A dual-side pulse-density-modulation WPT system is completely modeled as an example. Both the equivalent circuits and the mathematical descriptions are presented. The derived models are verified by large-signal step responses and small-signal frequency responses measured during experiments. As compared with the full-order models, the proposed reduced-order models have much more concise formulae while retaining high accuracy. [ABSTRACT FROM AUTHOR]

Using a photovoltaic (PV) emulator (PVE) simplifies the testing of the PV generation system. However, conventional controllers used for PVEs suffer from oscillating output voltage, requiring a high number of iterations, or being too complex to be implemented. This paper proposes a controller based on a resistance feedback control strategy that produces a stable and fast converging operating point for the PVE. The resistance feedback control strategy requires a new type of PV model, which is the current–resistance (I–R) PV model. This model is computed using a binary search method at a fast convergence rate. It is combined with a closed-loop buck converter using a proportional-integral controller to form the resistance feedback control strategy. The PVE's controller is implemented into dSPACE ds1104 hardware platform for experimental validation. The acquired experimental results show that the proposed PVE is able to follow the current–voltage characteristic of the PV module accurately. In addition, the PVE's efficiency is more than 90% under maximum power point operation. The transient response of the proposed PVE is similar to the PV panel during irradiance changes. [ABSTRACT FROM AUTHOR]

Powder cores have been gaining much attention as one of the attractive magnetic cores used in power converters due to their superior features such as high saturation flux density and their capability to suppress fringing flux due to the distributed airgaps. However, powder cores have a unique feature that the relative permeability of the magnetic core varies depending on the magnetic field intensity. The comprehensive modeling of variable relative permeability, design method of powder cores, and computer simulation methods are not well discussed in the relevant literature. This paper proposes a novel modeling, magnetic design method, and simulation technique considering dc superimposition characteristics of powder cores. The modeling method relies on a simple novel model equation representing the behavior of the variable relative permeability under the dc current superimposition condition, which is helpful to evaluate the performance of powder cores and to properly design various magnetic components. In this evaluation, five different magnetic powder cores are used to show the accuracy and properness of the proposed method. Theoretical analysis has been presented and the effectiveness of the proposed methods has been evaluated through simulation and experimental tests. [ABSTRACT FROM AUTHOR]

Models that accurately predict the output voltage ripple magnitude are essential for applications with stringent performance target for it. Impact of the dc input ripple on the output ripple for a frequency-controlled series resonant converter (SRC) using a discrete-domain exact discretization modeling method is analyzed in this paper. A novel discrete state-space model along with a small-signal model for the SRC considering three state variables is presented. The audiosusceptibility (AS) transfer function that relates the input-to-output ripple is derived from the small-signal model. Analysis of the AS transfer function indicates a resonance peak and an expression is derived connecting the AS resonance frequency for the input ripple based on the SRC component values. Further analysis is done to show that a set of values for the SRC parameter exists, which forms a design space, for which the normalized gain offered by the SRC for the input ripple is less than unity at any input ripple frequency. A test setup to introduce the variable frequency ripple at the input of the SRC for the experimental evaluation of the AS transfer function is developed. Influence of stray parameters on the AS gain, AS resonance frequency, and on the SRC tank resonance frequency is evaluated. An SRC is designed at a power level of 10 kW. The analysis using the derived analytical model, simulations, and experimental results are found to be closely matching. [ABSTRACT FROM AUTHOR]

This paper presents new studies of $dv/ dt$ -induced low-side mosfet false trigger when the high-side mosfet is turned on in synchronous buck converters. New analytical expressions are derived and utilized to predict both the magnitude and duration of the false triggering pulse to reveal more physical insight into the phenomenon. In contrast to the existing simple analytical model, the new model takes into account effects of nonlinear time-varying nature of the low-side mosfet drain-to-source capacitance $dv/ dt$ , the low-side mosfet body-diode reverse-recovery current and common-source inductance during the entire high-side mosfet turn-on transition. On the other hand, unlike the high-order complex model, which can only be solved numerically, the proposed analytical model is expressed explicitly by a set of parasitic parameters, and consequently their effects on the low-side mosfet false trigger can be explored much more easily. The model is mostly suitable for low-voltage applications in which false turn-on of the low-side mosfet could happen more often than under high-voltage conditions due to lower mosfet gate threshold voltage and higher $dv/ dt$. The model is tested on an experimental 12–1.35 V, 8 A synchronous buck converter, and predictions are compared with experimental data with favorable correlation. [ABSTRACT FROM AUTHOR]

Nonlinearities have been the major obstructions that limit the computational efficiency in power electronic circuit simulation for a long time. Yet there is no standard way for dealing with them. This paper presents a new method that makes the handling of nonlinearities fast and stable. In the proposed method, nonlinearities are transformed into a uniform representation—a constant resistor in parallel with a companion current source, thus making the system admittance matrix constant for fixed time-step simulation. To solve for the corresponding companion current source, nonlinearities are treated as either current or voltage sources and a diagonal time-varying matrix equation is developed. Three methods are proposed for solving the matrix equation—precomputed inversion or factorization, modified Gaussian elimination, and updating inverse using the Sherman–Morrison formula—that can fit different system sizes and applications. The proposed method is validated by two common power electronic converter topologies, both in offline and real-time simulation. Offline tests show that the proposed method achieved the same accuracy with the mature simulation software while being more than ten times faster. The same test cases are also implemented into field programmable gate arrays based real-time simulation experiments for verification. [ABSTRACT FROM AUTHOR]

Three-phase $LLC$ resonant converters can handle very high power levels beyond the capabilities of half-bridge and full-bridge $LLC$ topologies. Among other characteristics, three-phase $LLC$ structures reduce output current ripple (small output filter), enable parallel power processing (low peak current), and provide good thermal distribution. However, all these key advantages can be severely compromised due to passive components tolerances, leading to undesired current balance issues in three-phase $LLC$ resonant converters. Tolerances in resonant tank passive components are inevitable and lead to unequal peak currents between phases, uneven temperature distribution, and large output current ripple. This paper investigates the imbalances in three-phase $LLC$ converters and proposes a novel trigonometric current balancing (TCB) technique using phasor analysis. In this strategy, the required input voltage phase angles are calculated to achieve balanced phase currents, even under severe unbalanced conditions. In some cases, the output filter current ripple is reduced to less than half. The methodology is verified with a 3-kW experimental prototype, which validates the analytical framework and effectiveness of TCB. [ABSTRACT FROM AUTHOR]

A new implementation of an iron-loss model for laminated magnetic cores in the MATLAB/Simulink environment is proposed in this paper. The model is based on numerically solving a one-dimensional diffusion problem for the eddy currents in the core lamination and applying an accurate hysteresis model as the constitutive law. An excess loss model is also considered. The model is identified merely based on the catalog data provided by the core material manufacturer. The implementation is validated with analytical and finite-element models and experimentally in the case of a toroidal inductor supplied from a GaN FET full-bridge inverter with 5–500 kHz switching frequencies and a deadtime of 300 ns. Despite the simple identification, a good correspondence is observed between the simulated and measured iron losses, the average difference being 3.3% over the wide switching frequency range. It is shown that accounting for the skin effect in the laminations is significant, in order to correctly model the iron losses at different switching frequencies. Some differences between the measured and simulated results at high switching frequencies are also discussed. The model is concluded to be applicable for designing and analyzing laminated magnetic cores in combination with power-electronics circuits. The Simulink models are openly available. [ABSTRACT FROM AUTHOR]

This paper presents an improved compact model for a discrete silicon-carbide (SiC) MOSFET. This compact model based on the previous model features a new behavioral model of output characteristics and new nonlinear models of internal capacitors. Simulation with the improved compact model is in better agreement with measurement than that with the previous compact model, as well as transient behavior of the drain–source voltage, the drain current, and the leakage current out of a heatsink. Furthermore, the improved model is useful for constructing the accurate compact model that can reproduce the high-frequency characteristics of the transient waveforms of SiC-MOSFET s. This successful validation indicates that the improved compact model would be a promising tool for a full-simulation-based design system of the power converters using SiC-MOSFETs. [ABSTRACT FROM AUTHOR]

An important feature of an inductive power transfer (IPT) system is its power transfer efficiency and capability can be significantly affected by the load and the magnetic coupling variations. Therefore, identifying the load and the mutual inductance is essential to improve the system performance. This paper proposes a load and mutual inductance identification method for IPT systems with parallel-compensated power pickups based only on the information detected from the primary side. The proposed method can be implemented for primary resonant circuits whether they are series or parallel tuned, or with a hybrid compensation, such as an LCL configuration. An identification model is established according to the steady-state characteristics of the system. Identification results are obtained based on mathematical derivations and analyses. The proposed identification method is realized without any extra communication or control, and both the simulation and experimental results have verified its feasibility. [ABSTRACT FROM AUTHOR]

In this paper, two control strategies for voltage balancing in a modular serial parallel resonant converter modulator system, which is used in a high-voltage-pulsed power application, are presented and verified by simulations and measurements. The system is based on two series parallel resonant converter modules, forming an input series output parallel stack. To obtain the given output voltage pulse of 115 kV, nine of these input series output parallel stacks are connected in parallel at the input and in series at the output, forming an input parallel output series system. A robust input voltage balancing by an auxiliary circuit and an output voltage balancing by control is introduced and proven by measurements. In addition, an alternative approach, where the input and output voltage balancing is achieved purely by control, is given and verified by simulations. For designing the control of this system, a large and a small signal model is derived and the influence of component tolerances is investigated. [ABSTRACT FROM AUTHOR]

Switched-capacitor (SC) converters have drawn more and more attention in recent years due to their unique advantages. The accurate analysis methods will fully determine an SC converter's steady-state and dynamical performance. Proper design of SC converters requires full understanding of all impacts on circuit operation including steady-state and dynamical performance. Some previous modeling methods for SC converters have established a popular static model for SC converters which is composed of an ideal transformer and equivalent output resistance. This paper presents a dynamic capacitor ampere-second balance transient calculation modeling method. The instantaneous state of input voltage, instantaneous state of output voltage, instantaneous state of voltage of flying capacitor, “on time” and “off time,” as well as switching period are all included in the proposed model. The proposed modeling method was applied in both the dual-phase SC converters and the two-switch boosting SC converters. This modeling method was validated by the simulation and experimental results. The proposed model can be used to accurately predict and optimize the performance in the design phase for the low and high power SC converters. Based on the proposed modeling method, the SC converters could be controlled by a variable frequency control method. [ABSTRACT FROM AUTHOR]

Resonant power conversion leads to advantages such as soft switching and high-frequency operation; however, analysis and design of a resonant converter require an efficient methodology. In general, conventional methodologies use a design-oriented architecture, which requires previously specifications and iterative circuit-level simulations. This procedure is the simplest; notwithstanding, it can be time consuming and inaccurate for more complex systems, as resonant converters. This paper proposes a result-oriented architecture that is independent of specifications; in other words, real circuit parameters are waived in exchange for generalized results. A normalization procedure is proposed by using an equivalence transformation to modeling the system with a state vector composed of terms as the square roots of the stored energy in the reactive components. The system is represented in a dimensionless state-space model, in which the terms of the state-space matrices are composed of resonant parameters, such as normalized resonant frequencies and quality factor; thereby, the system is independent of circuit parameters, such as inductances, capacitances, and resistances. The sixth-order hybrid Ćuk converter is used to derivate the equations. Simulation results and an implementation of a 500-kHz hybrid buck converter are shown to compare theoretical, simulation, and experimental results. [ABSTRACT FROM AUTHOR]

For dc–dc converters with pulsating output current, such as boost and buck–boost converters, the use of leading-edge or trailing-edge pulse width modulation (PWM) can result in distinctly different behavior. This phenomenon is not readily captured by the usual averaged model but can be predicted with a discrete-time model. However, the discrete-time model, which tracks the dynamics of state variables over a switching period, is usually more complex and less convenient to apply for the design of the feedback control. Based on the low-pass characteristics of dc–dc converters, an approximate discrete-time model is proposed in this paper, and upon transforming to the s-domain, the model results in transfer functions that can be conveniently used for deriving practical closed-loop parameters. With the proposed model, the loop gain, the input and output impedances are derived and analyzed. The effects of applying different types of PWM on the stability of a single dc–dc converter and a system of cascaded dc–dc converters are discussed. Finally, prototypes of a buck converter, a boost converter, and a cascaded system of buck and boost converters are constructed to verify the effectiveness of the approximate discrete-time model. [ABSTRACT FROM AUTHOR]

Interleaved multiphase synchronous buck converters are often used to power computer CPU, GPU, and memory to meet the demands for increasing load current and fast current slew rate of the processors. This paper reports and explains undesired coupling between discrete inductors in typical commercial multiphase applications where space is limited. In this paper, equations of coupling coefficient are derived for single-turn and multiturn Ferrite core inductors commonly used in multiphase converters and are verified by Maxwell static simulation. The influence of the coupling effect on inductor current waveforms is demonstrated by Maxwell transient simulation and confirmed by experiments. The analysis provides a useful tool for mitigating the coupling effect in multiphase converters to avoid early inductor saturation and interference between phases. Design guidelines and recommendations are provided to minimize the unwanted coupling effect in multiphase converters. [ABSTRACT FROM AUTHOR]

This paper presents a reference modification model digitally controlled dc–dc converter. The proposed method is able to obtain superior transient response because it modifies a reference of conventional feedback loop against the change of output voltage. The modifying process operates only in the transient state. During the steady state, the feedforward control cancels a steady-state-error. Since the feedforward control uses the load current value, this paper discusses two current-sensing methods. One is the output current-sensing method using the sensing resistor, and the reactor current-sensing method using the R–C filter is discussed in order to reduce a performance loss by the sensing resistor. As a result, the output current-sensing method is effective in case that high-transient-response performance is required. On the other hand, it is better to use the reactor current-sensing method when efficiency is important. [ABSTRACT FROM AUTHOR]

This paper presents an in-depth critical discussion and derivation of a detailed small-signal analysis of the phase-shifted full-bridge (PSFB) converter. Circuit parasitics, resonant inductance, and transformer turns ratio have all been taken into account in the evaluation of this topology's open-loop control-to-output, line-to-output, and load-to-output transfer functions. Accordingly, the significant impact of losses and resonant inductance on the converter's transfer functions is highlighted. The enhanced dynamic model proposed in this paper enables the correct design of the converter compensator, including the effect of parasitics on the dynamic behavior of the PSFB converter. Detailed experimental results for a real-life 36 V-to-14 V/10 A PSFB industrial application show excellent agreement with the predictions from the model proposed herein. [ABSTRACT FROM AUTHOR]

Switched-capacitor (SC) converter is a type of variable structure systems. SC converters are typically equipped with open-loop control or some linear feedback control methods. However, these approaches provide slow dynamic response speed, small operation region, and large voltage ripple. Some new nonlinear control methods have been proposed in the literature to overcome these barriers. However, such control methods are usually proposed for applications involving low-power SC converters due to the limitations of them. This paper presents a nonlinear constant on-time variable frequency one-cycle control (CVFOCC) strategy based on dynamic capacitor ampere-second balance transient calculation (CASBTC) modeling method and one-cycle control (OCC) technique for high-power SC converters. This method successfully addresses the regulation issue of high-power SC converters. A high-power 3X Two-switch Boosting Switched-Capacitor converter (TBSC) is employed as an example topology. Simulation and experimental results both demonstrate that CVFOCC method could significantly improve the dynamic response speed and achieve excellent line and load regulation for the high-power SC converter in wide operation range. [ABSTRACT FROM AUTHOR]

Device-level power electronic circuit simulation is so cumbersome that engineers are forced to make model simplification or reduce circuit size to obtain a reasonable execution time for repeated simulation runs. This paper proposes a massive-thread parallel simulation of large-scale power electronic circuits employing device-level modeling on the graphics processors (GPUs) to obtain higher data throughput and lower execution times. Parallel massive-thread modules are proposed for the nonlinear physics-based insulated gate bipolar transistor and power diode components. The nonlinear solution algorithm comprised of Newton–Raphson iterations and partial LU decomposition is fully parallelized on the GPU. Furthermore, the commonly used behavioral model with reduced computational complexity is also employed to represent the switches. The developed simulation codes are used to run large-scale test cases of the modular multilevel converter (MMC) system. The accuracy and efficiency of the GPU-based parallel simulation are compared with sequential CPU-based codes and the SaberRD program to show the advantages of the parallelized simulation; execution time speedups of 15 times and 70 times are reported for the MMC system using the nonlinear physics-based modeling and behavior-based modeling, respectively. [ABSTRACT FROM AUTHOR]

Switched capacitor converters with ideal switches exhibit discontinuities in the electrical variables, i.e., state jumps at the switching time instants. This feature introduces some difficulties for the determination of compact dynamic models for these power converters. In this paper, we tackle the issue by considering a switched model where the dynamics of the modes are represented through differential algebraic equations. For this class of systems the classical averaged model fails. By including a suitable jump mode that approximates the state discontinuities, a generalized frequency-dependent averaged model is proposed. The effectiveness of the switched and averaged models is numerically and experimentally verified by analyzing the ladder, series–parallel, Fibonacci, and Dickson topologies, and by considering different switching frequencies, voltage sources, and circuits parameters. [ABSTRACT FROM PUBLISHER]

Detailed thermal dynamics of high-power IGBT modules are important information for the reliability analysis and thermal design of power electronic systems. However, the existing thermal models have their limits to correctly predict these complicated thermal behavior in the IGBTs: The typically used thermal model based on one-dimensional RC lumps have limits to provide temperature distributions inside the device; moreover, some variable factors in the real-field applications like the cooling and heating conditions of the converter cannot be adapted. On the other hand, the more advanced three-dimensional (3-D) thermal models based on finite-element method (FEM) need massive computations, which make the long-term thermal dynamics difficult to calculate. In this paper, a new lumped 3-D thermal model is proposed, which can be easily characterized from FEM simulations and can acquire the critical thermal distribution under long-term studies. Meanwhile, the boundary conditions for the thermal analysis are modeled and included, which can be adapted to different real-field applications of power electronic converters. Finally, the accuracy of the proposed thermal model is verified by FEM simulations and experimental results show a good agreement. [ABSTRACT FROM PUBLISHER]

Silicon carbide (SiC) power metal–oxide–semiconductor field-effect transistors (mosfets) have been applied in high-power and high-frequency converters recently. To effectively predict characteristics of SiC power mosfets in the design phase, a simple and valid model is needed. In this paper, a simple improved SiC power mosfet behavioral model is proposed using SPICE language. Key parameters in the model are analyzed and determined in detail, including parasitic parameters of the power module, steady-state characteristic parameters, and nonlinear parasitic capacitances. The effect of negative turn-off gate drive voltage is considered and a continuously differentiable function is proposed to describe the gate–source capacitance. Experimental validation is performed under a double pulse circuit employing an N-channel power mosfet half-bridge module CAS300M12BM2 (Cree Inc.) rated at 300 A/1200 V. The main switching dynamic characteristic parameters of the model have been compared with those of the measured results. The results show that taking gate–source capacitance as a linear value as most previous models do will cause significant turn-on deviations between experiment and simulation results, while the improved model is more accurate compared with the measured results. [ABSTRACT FROM AUTHOR]

LLC resonant converter is a nonlinear system, limiting the use of typical linear control methods. This paper proposed a new nonlinear control strategy, using load feedback linearization for an LLC resonant converter. Compared with the conventional PI controllers, the proposed feedback linearized control strategy can achieve better performance with elimination of the nonlinear characteristics. The LLC resonant converter's dynamic model is built based on fundamental harmonic approximation using extended describing function. By assuming the dynamics of resonant network is much faster than the output voltage and controller, the LLC resonant converter's model is simplified from seven-order state equations to two-order ones. Then, the feedback linearized control strategy is presented. A double loop PI controller is designed to regulate the modulation voltage. The switching frequency can be calculated as a function of the load, input voltage, and modulation voltage. Finally, a 200 W laboratory prototype is built to verify the proposed control scheme. The settling time of the LLC resonant converter is reduced from 38.8 to 20.4 ms under the positive load step using the proposed controller. Experimental results prove the superiority of the proposed feedback linearized controller over the conventional PI controller. [ABSTRACT FROM PUBLISHER]

In power electronic applications, aging of the electric double layer capacitors (EDLCs) is considered as a serious issue since it may lead to failure. Their degradation is usually evaluated by an increase of the internal resistance or a decrease of the equivalent capacitance. These aging indicators have a good correlation with the supercapacitor's state-of-health (SoH). Generally, SoH is measured by electrochemical impedance spectroscopy (EIS). However, this technique must be performed offline and requires interruption of the system's operation. In this paper, a sliding mode observer is designed to estimate online the EDLC's aging indicators. Unlike several online estimators, the supercapacitor's parameters are considered as a nonlinear random distribution with external noises which yields accurate estimation. In addition, the relationship between the capacitance and the bias voltage is considered to be nonlinear. Lyapunov stability analysis is also provided. The proposed approach is validated experimentally using a standardized dynamic current profile. Furthermore, comparison against EIS is carried out for different aging phases and under different environmental temperature conditions. [ABSTRACT FROM PUBLISHER]

The objective of this paper is to propose an efficiency model to evaluate the impact of the pulse width modulation (PWM) duty cycle jitter on the efficiency of switching-mode power converter. By taking the product of two perturbation terms into consideration, which is ignored in the conventional average small-signal model, the average efficiency model is proposed first. Due to the nonlinear characteristic of the PWM generator, the multifrequency efficiency model is also developed by considering the sideband frequency. Three different perturbation waves are induced to the control loop of the converter to generate the jitter to observe its impact on the efficiency. The mathematical expression of the efficiency drop based on the proposed multifrequency model is derived. The reason of control-to-output gain's magnitude spike on the Bode plot can be explained by the derived equations. Eventually, the methods to reduce the efficiency drop caused by the jitter are suggested. In spite of various perturbation frequencies, amplitudes, and waveforms, the mathematical calculation, the computer simulation, and the hardware measurement of the efficiency drop are consistent which validate the accuracy of the proposed multifrequency efficiency model. [ABSTRACT FROM AUTHOR]

An increasing number of power-electronic-based distributed generation systems and loads generate not only characteristic harmonics but also unexpected harmonics. Several methods, such as impedance-based analysis, which are derived from the conventional average model, are introduced to perform research about the harmonic interaction. However, it is found that the linear-time-invariant-based model analysis makes it difficult to analyze these phenomena because of the time-varying properties of the power-electronic-based systems. This paper investigates a grid-connected converter by using the harmonic state-space (HSS) small-signal model, which is based on a linear time-varying periodically theory. The proposed model can include the switching behavior of the model, where it makes the model possible to analyze how harmonics are transferred into both the ac-side and dc-side circuits. Furthermore, a harmonic matrix of the grid-connected converter is developed to analyze the harmonic interaction at the steady-state behavior. Besides, the frequency-domain results are compared with time-domain simulation results by using the HSS modeling to verify the theoretical analysis. Experimental results are finally discussed to verify the proposed model and study. [ABSTRACT FROM PUBLISHER]

This paper presents the method of modeling single-inductor dc–dc converters with thermal phenomena in the inductor taken into account. The electrothermal models of an inductor and semiconductor devices in the form dedicated for SPICE are proposed. Using the proposed models, the electrothermal analysis of buck and boost converters was performed for the inductor with cores made of different ferromagnetic materials. It was proved that nonlinearity of the inductor characteristics and thermal phenomena occurring in this element should be taken into account when the converter operates at high frequency range (over 200 kHz), especially for the inductor with the powder core. [ABSTRACT FROM PUBLISHER]

Diode–capacitor-based dc–dc converters provide a simple and low cost solution for high step-up voltage regulation in solar and fuel cell generation. Transient modeling analysis reveals their worse influence of nonlinear and nonminimum-phase system characteristic due to right-half-plane (RHP) zero, especially in high voltage gain application. However, the process of energy transfer for diode–capacitor-based dc–dc converter is different from basic dc–dc converter. Based on the unique feature, this paper proposes an improved main circuit structure with parallel connection of resistive–capacitive damping network across the intermediate capacitor to achieve good dynamic performance. By optimal parameter design according to Routh–Hurtwitz criterion, all the RHP zeros in the transfer function of control-to-output voltage are eliminated completely. Then, by the case of diode–capacitor-based boost converter, the adaptive PI controller is designed to deal with nonlinear characteristic of voltage gain. It gets good dynamic performance under wide range output voltage. All the theoretical findings and design approaches are verified by simulation and experiment results. The existing diode–capacitor-based high step-up dc–dc converters with slight main circuit modification are more promising in renewable energy application. [ABSTRACT FROM AUTHOR]

Like any electric energy storage system, supercapacitors have a limited lifetime. Indeed, they degrade with time because of parasitic reactions between electrodes and electrolyte. Porous electrodes are complex structures and pores have size dispersion because of manufacturing processes. This paper proposes to study the specific impact of supercapacitor floating ageing on different pore sizes using a multipore model. The multipore model is an equivalent electrical circuit model, capable of representing impedance behavior of supercapacitor in full range of its operating frequencies and classifying different sized pores by their impedance parameters. This paper first presents a link between pore sizes and impedance parameters of the modeling circuit. Then, floating ageing experiments are carried out using three samples from two different manufacturers. Multipore model impedance parameters evolution is monitored and discussed. Finally, a new representation of ageing processes is proposed by pore size and for different ageing phases. [ABSTRACT FROM AUTHOR]

Parasitic capacitances of the high-frequency (HF) transformer used in dc–dc converter impact harmonic analysis of the transformer and interactions with the converter. Resonant frequencies of open- and short-circuit impedances characteristics (ICs) have been widely used to extract parasitic capacitances of HF transformers, but it was reported that some resonant frequencies were unobtainable as they were too high where the ICs fluctuated heavily, and parasitic capacitances remained unevaluated. In this paper, resonance features of ICs and voltage transfer characteristics (TCs) are investigated, and a new frequency of voltage TC is used for extracting parasitic capacitances. By analyzing inner links of known impedance resonant frequencies, why and which resonant frequencies are likely to be unobtainable is revealed. Furthermore, a new frequency corresponding to zero of TC, accounting for parallel resonance between leakage inductance and mutual capacitance of the two windings, is used to extract parasitic capacitances. With this new frequency mutual capacitance of the windings is evaluated, and missing equation due to unobtainable impedance resonant frequency is added. Besides, merits and limitations of extracting parasitic capacitances based on ICs and TCs are analyzed. These techniques are verified with several HF transformer prototypes in the laboratory. [ABSTRACT FROM AUTHOR]

In this paper, a temperature-dependent compact SPICE model of reverse-conducting IGBTs (RC-IGBTs) is presented. The proposed solution is based on a quasi-two-dimensional (2-D) approach, with the use of IGBT and p-i-n diode subcircuits suitably connected to take into account the inner interactions among the two devices. The resulting device model is derived through physical considerations on the RC-IGBT internal behavior, carried out by means of wide area TCAD 2-D simulations. Transversal current path, localized lifetime control effects, and turn-on dynamics are also included into the model. The model shows good robustness properties, even in demanding numerical conditions. Validation of the SPICE model with experiments performed on a 1.2-kV 30-A commercial device, in both static and dynamic conditions, demonstrates its remarkable correctness and accuracy. To further confirm the applicability of the proposed model in real-operating conditions, a quasi-resonant converter has been realized and the measurements on the realized circuit have been successfully compared with the results obtained with the proposed model. [ABSTRACT FROM AUTHOR]

By the logical statements and linear inequalities, a new modeling method named bi-switching status modeling (BSM) method is presented to model the dc–dc converters in this paper. Compared with other modeling methods, such as the state-space averaging method and the mixed logical dynamical (MLD) method, first, the BSM method can describe continuous conduction mode and discontinuous conduction mode operations of the dc–dc converters as a unified bi-switching status model. Second, the BSM method is more precise than the state-space averaging method because there is no approximate assumption. Third, the constrains of the operating modes in the BSM method can be simplified as a consolidated inequality, which means that the model obtained by the BSM method is more concise than that obtained by the MLD method. Simulation and available experiments of a buck converter verify the effectiveness of the proposed BSM method. [ABSTRACT FROM PUBLISHER]

From the controller design framework, a simple analytical model that captures the dominant behavior in the range of interest is the optimal. When modeling resonant circuits, complex mathematical models are obtained. These high-order models are not the most suitable for controller design. Although some assumptions can be made for simplifying these models, variable frequency operation or load uncertainty can make these premises no longer valid. In this study, a systematic modeling order reduction technique, slowly varying amplitude and phase (SVAP), is considered for obtaining simpler analytical models of resonant inverters. SVAP gives identical results as the classical model-order residualization technique from automatic control theory. A slight modification of SVAP, slowly varying amplitude derivative and phase (SVADP) is applied in this paper to obtain a better validity range. SVADP is validated for a half-bridge series resonant inverter and for a high-order plant, a dual-half bridge series resonant inverter giving analytical second-order transfer functions for both topologies. Simulation and experimental results are provided to show the validity range of the reduced-order models. [ABSTRACT FROM PUBLISHER]

Computationally efficient high-frequency circuit models of long cables are necessary for accurate analysis of electromagnetic effects in power converter systems. In this paper, an advanced modeling technique utilizing different natural symmetries present in industrial power cables is introduced, resulting simultaneously in a significant reduction of the model complexity and an improved model precision as compared to the previously developed modeling methodology. Additionally, a method for extraction of the cable's per-unit-length parameters is derived allowing scalability of the developed model to arbitrary lengths for the cable of the same type. The developed methodology is validated by comparing the results obtained using simulations with the measurements in both frequency and time domain. [ABSTRACT FROM PUBLISHER]

Average-value modeling (AVM) provides an efficient way to study power electronic systems in large- and small-signal senses. This paper presents a new reduced-order AVM for dual-active-bridge dc–dc converters. The proposed model considers the conduction and transformer power losses as well as the input/output filters, which may be very useful for system-level studies. Based on the large-signal AVM, the small-signal model and the control-to-output transfer function are also derived. The proposed AVM is compared with the full-order generalized average model and the detailed model in predicting large-signal transients and small-signal analysis in the frequency domain. The experimental results confirm that the proposed model yields a high accuracy, which represents an improvement over other existing models. [ABSTRACT FROM PUBLISHER]

In this paper, average modeling and analysis of a dual-supercapacitor bank, actively balanced by a bidirectional buck–boost converter, is presented. In such a system, natural balancing is achieved when the converter is operated in open loop with 50% duty cycle, eliminating the need for measuring the voltage of each storage device. Nevertheless, excessive currents arise even for slight voltage misbalance because of the highly underdamped nature of the system. In order to remedy this drawback, bidirectional pulse-by-pulse inductor current limitation is introduced, which is equivalent to adding a peak-current-mode-like control loop to the system. Since the duty cycle never exceeds 50%, compensation ramp is not required to maintain stability. On the other hand, while the uncontrolled system dynamics is linear, introducing the current limit mechanism turns the closed-loop dynamics into a nonlinear one, burdening the analysis task and thus calling for suitable average model to perform fast simulations for system analysis. Therefore, dynamical equations of the system are developed in order to derive the switching-cycle-averaged model and reveal the tradeoff between current limit level, balancing time and efficiency for the worst case of imbalance. Simulations and experiments support the presented findings. [ABSTRACT FROM PUBLISHER]

A recently reported modeling methods for a switched capacitor converter either assume output as “firm” voltage or a resistor to facilitate calculation. When the size of output filter capacitor is moderate, accompanied by noticeable output ripple, previous modeling results may not provide accurate prediction and design guidelines. In this paper, a new modeling technique taking into account the output capacitor effect is proposed for simple dual-phase switched capacitor converters without complex coupling loops. The proposed model employs transient calculation, takes charge redistribution phase into account, and includes the duty cycle, switching frequency as well as output capacitor simultaneously in the final output impedance formula, which enhances accuracy of the model. It is suitable for interleaved and noninterleaved switched capacitor converters. The simulation and experimental results for the unity gain SC converter are provided to verify the proposed theory. [ABSTRACT FROM PUBLISHER]

Many analytical methods of establishing accurate models of the switched-capacitor (SC) converters have been developed. These methods are applicable to simple low-order SC converters and can permit only a general efficiency calculation of SC converters. They do not provide analytical solutions that describe how individual electrical component in the circuit practically affects the SC converter at different frequencies. Such an analysis is important for the optimal design and realization of a complex (high-order) SC converter. This is particularly true for those SC converters which have more than two operating states. For complex SC converters, a constituent capacitor may have a profound effect on the converter's efficiency and is dependent on the configuration of the switches and the arrangement of the energy flow paths. In this paper, the relationship of the value of capacitors and the efficiency of complex SC converters is derived and investigated using an energy-flow-path analysis. Optimal design of SC converters can be achieved through a systematic component value selection by: 1) increasing the proportion of energy flow through the most efficient paths; and 2) increasing the efficiency of the paths that have a higher energy flow. The design of complex SC converters in terms of optimizing their power efficiency is discussed using an exponential SC converter as an illustration. The results of both calculation and experimental measurement show that the approach is effective. [ABSTRACT FROM AUTHOR]

With the development of electric vehicles and consumer electronics, wireless power transfer (WPT) is becoming a popular technology. Recently, magnetic resonant coupling has been considered to be the most effective and attractive WPT approach, and the two-coil structure is the most widely used for magnetic resonant coupling. It has been recently reported that the system's energy efficiency can be improved by a three-coil structure. In this paper, the three-coil structure is compared with the two-coil structure based on circuit theory. Simplified circuit models of the two- and three-coil structures are proposed to give a more intuitive and comprehensive analysis of the energy efficiency differences between the two structures. With the simplified model, the condition for a three-coil structure obtaining higher energy efficiency over its two-coil counterpart is derived, and the analysis shows that the WPT system with higher energy efficiency within a wider range of loads can be achieved by properly designed three-coil systems. Additionally, it also shows that the three-coil system has the significant advantage of reducing the current stress and the electromagnetic field emission that is caused by misalignments. The theoretical analysis is confirmed by both simulation and experimental results. [ABSTRACT FROM AUTHOR]