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In recent years, very high frequency (VHF) converter has attracted much attention. However, with rich parasitic parameters and complex resonance links, there are some great difficulties to the modeling of such systems. Taking the on-off controlled VHF resonant boost converter as an example, this paper presents an accurate modeling and analysis method that considers multiple parasitic parameters. First, the closed-loop VHF converter system is divided into a main network and a parasitic oscillation network. Then, based on the operation analysis, an equivalent circuit model characterized by a time-varying input voltage source and two variable duty-cycle controlled switches is proposed. It worth noting that both the time-varying input and the controlled switches take into account the influences of the parameters. Furthermore, the periodic approximate analytical solution of the output voltage in the on stage is obtained by using the equivalent small parameter method to the proposed circuit model. And then combining the solution of the parasitic oscillation network and on-off state switching conditions, the steady-state waveform of output voltage can be obtained quickly. Finally, a prototype with operating frequency of 21.44 MHz is built to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a resonant switching cell model to analyze and design the single-ended resonant dc–dc converters. The single-ended zero-voltage switching (ZVS) converters such as the Class E converter are efficient for megahertz switching because they feature low turn-on and turn-off switching losses. Also, they use only a ground-referenced switch, allowing a simple gate drive circuit. In this paper, we investigate the single-ended resonant converter with the small input inductance, whereas the conventional Class E converter has a large input inductance. The main contribution of this paper is to propose the resonant switching cell as an analytic model that simplifies the analysis and the design of the resonant dc–dc converters. Furthermore, this paper presents the design method of the resonant switching cell model for minimizing the resonant current magnitude and conduction loss while the converter maintains ZVS property. The experimental results from a 10-MHz GaN-based prototype demonstrate the feasibility and effectiveness of the analysis and design based on the proposed resonant switching cell model. [ABSTRACT FROM AUTHOR]

In this paper, the pulsewidth modulation switch method was used to investigate the effect of the transformer leakage inductance on the small-signal model in isolated full-bridge converter. A galvanic isolated hard-switching full-bridge converter that operates in constant-current mode is analyzed, confirming that leakage inductance significantly affects the small-signal model, and the influence of leakage inductance can be equivalent to a resistance in series with the converter's output LC filter just as that in phase-shifted full-bridge converter. However, the same leakage inductance in these both converters will lead to different equivalent resistance due to different operating principles. Results of the modified model, simulations, and the experiments are compared to verify the correctness of the model. Moreover, this paper also shows that the Norton equivalent circuit of the charger operates in constant current mode, which can be used to estimate the dynamic behavior of the system. [ABSTRACT FROM AUTHOR]

The paper deals with some new results on the averaging theory approach for the analysis of feedback controlled pulsewidth modulation power electronic converters. It develops some considerations regarding the averaging approximation of time-variant differential systems proving an analytical relationship between the accuracy with which the solution of the averaged model converges to the solution of the original time-variant model (i.e., the switched model) and the switching frequency of the converters. This relation is valid both for stable and unstable systems. Moreover, this paper confirms, as corollary, that under suitable conditions (verified during the standard operations of the power electronic converters) the averaged model uniformly converges to the switched model. [ABSTRACT FROM AUTHOR]

The hard switching operation of the insulated gate bipolar transistor (IGBT)-based multilevel converters (MLCs) in the transformer less direct integration of renewable power plants produces a considerable amount of switching and conduction power loss. This eventually causes higher junction temperature and lower thermal stability. The symmetrically designed MLC using third harmonic sixty-degree bus-clamped pulse width modulation (BCPWM) technique demonstrates reduced switching losses and better harmonic spectra. However, the development of analytical power loss model is a complex and challenging issue due to the discontinuous switching mode of IGBTs for the BCPWM in MLC. In this regard, an analytical model for calculating the average and the rms currents for the hard switching operation of IGBTs and antiparallel diodes (APDs) with BCPWM is proposed. Furthermore, to calculate the device turn-on and turn-off losses, a discrete form of equation is presented to evaluate the transition times of switching more precisely. The numerical power loss values of IGBTs and APDs found from the derived analytical equations for MLC are compared with the simulation and experimental results. The numerical results agree well with the simulated and the experimental outcomes, which validate the proposed analytical loss model. Moreover, an advanced three dimensional thermal impedance model with chip-wise interdependent multilayer thermal coupling effect is also considered in this paper to realize the critical thermal loading condition of the switching devices. [ABSTRACT FROM AUTHOR]

The modeling and control of a buck–boost and stacked dual half-bridge (DHB) integrated bidirectional dc–dc converter have been studied in this paper. This converter features high-voltage transfer ratio, high efficiency, and the minimum number of switches. In this paper, an extended, continuous, full-order, state-space averaging modeling method is proposed. Compared with existing methods, the proposed method exhibits higher coincidence with the switching circuit simulation, in steady and especially dynamic states. Due to its high dynamic accuracy and low complexity, the proposed modeling method provides a better theoretical analysis and a fast simulation tool for transient process and control design of converters with dual-active-bridge units, especially with DHB units. By using this method, the high-frequency transformer series inductance current is directly divided into a sampled dc component and a fluctuant component. Only the sampled dc one is included into state variables, but both components are considered into state equations. Besides, this method regards the entire converter as a linear superposition of its subsections, which provides a stepwise modeling based on linearization of subsections. Moreover, a decoupled proportional-integral control method is proposed to enhance the stability and dynamic response of the converter. This control method is analyzed by the proposed models, which can be regarded as an application of the proposed modeling method. Simulation and experiments have validated both the proposed modeling and the decoupled control strategy. [ABSTRACT FROM PUBLISHER]

Generally, battery-fed capacitive loads are charged to high voltages in series of switching cycles with smaller fragments of energy delivered to the load in every cycle to ensure an efficient charging process. In high voltage low power (HVLP) flyback charging circuit, significant portion of input energy drawn from the source in a cycle is utilized by the effective parasitic capacitance of the HV transformer and semiconductor devices and circulated back to the source at the end of the cycle. This reduces the energy delivered to the load per cycle and hence the net energy delivered in the charging process. In this paper, an energy-based analysis and simplified energy-based model for HVLP charging circuits is derived. An energy-based approach is appropriate to describe and define the HVLP converter behavior in terms of load energy component and circulating energy component. The derived energy-based model is extended to obtain analytical closed-form expressions governing the essential parameters of the charging circuit. The proposed energy-based model and analytical formulation of essential parameters are experimentally validated on a 0–2.5 kV programmable high voltage charging circuit prototype fed from 12 V input battery source. [ABSTRACT FROM AUTHOR]

There currently exists a mature literature on modeling the aggregate load of a distribution feeder by making use of measurements at its feeder-head at substation. The primary application of such feeder-aggregated load models is in sub-transmission or transmission system analysis. However, there is a growing need in practice also to model each individual load across the feeder. If available, such individual load models have applications in power distribution system analysis, e.g., to better integrate distributed energy resources or to improve power quality and reliability. Motivated by this observation, in this paper, we propose a new method for individual load modeling in power distribution systems. It works by using the measurements only at the feeder-head. It takes an innovative approach to analyzing the load switching events across the distribution feeder itself, instead of or in addition to relying on upstream voltage events that are commonly used in feeder-aggregated load modeling. By tracking the downstream load switching events, the proposed method can make a robust estimation of the ZIP load model parameters for all individual loads. The proposed method is examined on small illustrative test-feeders as well as the IEEE 33-bus test system under various operating scenarios. The adverse impact of errors in measurements and system parameters are also investigated on the performance of the developed load modeling method. [ABSTRACT FROM AUTHOR]

Electrically excited synchronous machines have shown potential to be an alternative to permanent magnet synchronous machines in electromobility and wind power applications. High-frequency wireless power transferring technology enables a compact design of brushless exciters for the machine. In this paper, a dynamic model of high-frequency brushless exciters is proposed for the purposes of operating condition monitoring and excitation control. The modeling is done by using arithmetic and differential equations as well as considering different operation modes of the system. The operation modes are defined based on the physical behaviors of the excitation circuit. Experiments are performed to verify the model with variations of different circuit parameters. Furthermore, parameter sensitivity study, component parameter selection, and loss analysis are conducted to demonstrate the effectiveness of the model. The model is therefore proposed as an effective tool to assist the design and optimization of the brushless excitation system. [ABSTRACT FROM AUTHOR]

Synchronous rectification (SR) is one of the well-known methods to reduce the conduction losses by replacing the power diodes. The control of SR requires the phase information of the device current. In this paper, a novel extended harmonics approximation modeling approach is introduced for CLLC resonant converters to estimate the phase of its secondary side current accurately. Conventionally, the first harmonic approximation (FHA) is used to model any resonant converter; however, FHA works more accurately near the resonant frequency operation. But in case of a set of unmatched LC tank parameters in the primary and secondary side of a CLLC converter, there is no uniquely defined resonant frequency, which reduces the accuracy of the FHA model. Unlike FHA-based approach, our proposed modeling considers the effects of other odd order harmonics present in the square wave voltage waveform towards determining the zero-crossing instant or phase information of the resonant currents. The proposed concept is verified through experimental results obtained at 3.3-kW load condition, and the converter efficiency is improved by 1.8% with the proposed phase tracking technique, compared to FHA modeling approach. [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]

Taking switching transients of switching devices into consideration in design and simulation of power electronic systems has long been a huge obstacle. Sufficient accuracy has to be ensured, meanwhile more significantly the transient model has to be practical, i.e., providing a convergent result with an acceptable solving speed and a convenient parameter extraction technique. Aiming at both targets, this paper proposes a piecewise analytical transient (PAT) model for switching device commutation unit, taking an IGBT–p-i-n diode pair as an example. A piecewise time-varying voltage source-current source pair is utilized to model the IGBT–p-i-n diode pair. With sufficient accuracy, PAT modeling methodology noticeably increases the solving speed and improves the convergence of converter simulations. Model expressions and datasheet-driven parameter extractions are illustrated in detail. Experimental and simulated results are presented and compared to validate both the accuracy and the practicability of the proposed PAT model, expected to be employed in transient simulations of power electronic systems. [ABSTRACT FROM AUTHOR]

To solve the problem of poor robustness due to the high dependence of model predictive control (MPC) on the three-phase inverter model, the influence mechanism of the mismatch of circuit parameters R and L, the model discretization error, and sampling errors on MPC prediction error are analyzed in this paper. A feedback self-correction is proposed, which the next current errors are predicted and used to modify the model, based on the previous prediction errors. This proposed method involves simple structure and a small amount of calculation. Steady-state effects of the proposed method are quantized to prove a good inhibitory ability on multifactorial prediction errors. Finally, experimental results in a three-phase inverter are presented to support the theoretical analysis and demonstrate the feasibility of the proposed method. [ABSTRACT FROM AUTHOR]

Over the past years, the linearized modeling techniques for power converters have been continuously developed to capture the small-signal dynamics beyond half the switching frequency. This paper reviews and compares the small-signal modeling approaches based on a buck converter with voltage-mode control. The study includes the small-signal averaged modeling approach, the describing function method, and the harmonic state-space modeling approach, in order to be able to better select the correct method when modeling and analyzing a power electronic circuit as well as a power-electronic-based power system. The model comparison points out that the describing-function-based models do improve the modeling accuracy beyond the half-switching frequency of the converter, yet they fail to predict the frequency-coupling interactions (e.g., beat frequency oscillations) among multiple converters, and instead, harmonic state-space models in the multiple-input multiple-output form are required. [ABSTRACT FROM AUTHOR]

Power converters in the system-level real-time simulation are usually emulated by L/C-based associated discrete circuit (L/C-ADC). However, the L/C-ADC approaches may suffer from two issues: How to mitigate the unacceptable virtual power loss especially in high-frequency applications, and how to tune LC parameters setting which is affected by the external circuit. This paper proposes a novel generalized associated discrete circuit (G-ADC) model with parameterized history current sources. By utilizing the stability region of the feasible parameter space, the optimized G-ADC models with the best damping characteristic are developed for both two-level and three-level converters. The analytical results also guarantee that the parameters of the optimized G-ADC model are independent of the external circuit for most power grid applications. Furthermore, an field programmable gate array (FPGA)-based real-time simulation platform is built to verify the feasibility of the proposed scheme. Extensive simulation and hardware-in-loop experiment results demonstrate the effectiveness and superiority of best-damped models as well as the modeling flexibility corresponding to insensitivity to operating conditions and external system parameters. [ABSTRACT FROM AUTHOR]

Performance of the crossbar memory array highly depends on the selector characteristics. In this paper, rigorous transient analyses are performed for a large-size crossbar memory array using novel NbO2-based selectors with a threshold switching behavior. To enable accurate and efficient array-level simulation, an electrostatic discharge-based compact model is employed to effectively describe the ${I}$ – ${V}$ characteristics of the selector. Multiple key design parameters of the selector are investigated, such as the threshold voltage, leakage current, and intrinsic switching speed. A sensitivity analysis is performed to evaluate the impact of hypothetical improvements in various selector parameters. In addition, the impacts of resistances of interconnect and memory element on the array-level access delay and energy dissipation are quantified. The results show that reducing the threshold voltage of selectors provides the most significant performance improvement, where up to 80% of the energy-delay product saving is observed if the threshold voltage is reduced by 50%. [ABSTRACT FROM AUTHOR]

In this paper, a self-triggering linear transformer driver (LTD) technology based on the principle of electromagnetic induction is presented. A detailed circuit model of the self-triggering LTD module is established in PSPICE to explore the feasibility of the self-triggering method. Through simulation and analysis, an original design of a prototype self-triggering LTD is established. Some factors, which influence the performance of the self-triggering LTD are demonstrated and analyzed thoroughly in this paper, such as peaks of induced trigger voltages and pre-magnetizing. Simulation results indicate that all induction cavities in the self-triggering LTD module can be triggered with an easier external trigger method and the cavity triggering sequence is acceptable. The peak current at the output of self-trigger LTD module is in the range of 0.96 MA to 1.01 MA and the 10-90% rise time is about 31ns in the simulation. [ABSTRACT FROM PUBLISHER]

Dual active bridge (DAB) converters have been widely used in distributed power systems and energy storage equipment. However, the inherent nonlinearity of the DAB converters can cause stability problem, such as output voltage oscillation. In this paper, the dynamic behavior and stability of a digitally controlled DAB converter with a closed-loop controller are studied. First, to accurately study the nonlinear dynamics and stability in a DAB converter, a bilinear discrete-time model considering the output capacitor equivalent series resistance (ESR) and the digital control delay in circuit is established. Based on the model, the nonlinear dynamic characteristic and stability of the DAB converter versus the control parameter are studied. Furthermore, extensive analyses are performed to study the effect of the transformer leakage inductance and the output capacitor ESR on the stability boundaries of the control parameter. The accuracy of the model and the theoretical analyses are validated by simulation and experimental results. The proposed model of the digitally controlled DAB converter can accurately predict the stability boundaries, which can be effectively applied to the design of the system parameters and guarantee stable operation of the converter. [ABSTRACT FROM AUTHOR]

The aim of this paper is to introduce a compact model for perpendicular spin-transfer torque (STT)-magnetic tunnel junctions (MTJs) implemented in Verilog-A to assure easy integration with electrical circuit simulators. It takes into account the effects of voltage-dependent perpendicular magnetic anisotropy, temperature-dependent parameters, thermal heating/cooling, MTJ process variations, and the spin-torque asymmetry of the Slonczewski spin-polarization function in the switching process. This translates into a comprehensive modeling that was adopted to investigate the writing performance under voltage scaling of a $256\times256$ STT- magnetic random access memory array implemented at three different technology nodes. Obtained results show that scaling from 30- to 20-nm node allows a write energy saving of about 43%, while the supply voltage that assures the minimum-energy write operation increases. [ABSTRACT FROM PUBLISHER]

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]

Compared with the state-of-the-art Si-based power devices, enhancement-mode Gallium Nitride (E-mode GaN) transistors have better figures of merit and exhibit great potential in enabling higher switching frequency, higher efficiency, and higher power density for power converters. The bridge-leg configuration circuit, consisting of a controlling switch and a synchronous switch, is a critical component in many power converters. However, owing to the low threshold voltage and fast switching speed, E-mode GaN devices are more prone to false turn-on phenomenon in bridge-leg configuration, leading to undesirable results, such as higher switching loss, circuit oscillation, and shoot through. In order to expand gate terminal's safe operating margin without increasing reverse conduction loss during deadtime, negative gate voltage bias for turn-off and antiparallel diode could be applied to E-mode GaN device. In this paper, with consideration of strong nonlinearities in C–V and I–V characteristics of high-voltage (650 V) E-mode GaN transistors, analytical device models are first developed. Then, we develop an analytical circuit model that combines the circuit parameters with intrinsic characteristics of the high-voltage GaN transistor and antiparallel diode. Thus, key transient waveforms with regard to the false turn-on problem can be acquired, including displacement current and false triggering voltage pulse on gate terminal. The simulated waveforms are then verified on a testing board with GaN-based bridge-leg circuit. In contrast to piecewise switching process models and PSpice simulation, the proposed model exhibits outstanding performances. To provide design guidelines for mitigating false turn-on of GaN transistor, the impacts of different circuit parameters, along with the optimum negative gate voltage bias, are investigated based on 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]

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]

This paper presents a new method, called multicycle Q-modulation, which can be used in wireless power transmission (WPT) to modulate the quality factor (Q) of the receiver (Rx) coil and dynamically optimize the load impedance to maximize the power transfer efficiency (PTE) in two-coil links. A key advantage of the proposed method is that it can be easily implemented using off-the-shelf components without requiring fast switching at or above the carrier frequency, which is more suitable for integrated circuit design. Moreover, the proposed technique does not need any sophisticated synchronization between the power carrier and Q-modulation switching pulses. The multicycle Q-modulation is analyzed theoretically by a lumped circuit model, and verified in simulation and measurement using an off-the-shelf prototype. Automatic resonance tuning in the Rx, combined with multicycle Q-modulation helped maximizing PTE of the inductive link dynamically in the presence of environmental and loading variations, which can otherwise significantly degrade the PTE in multicoil settings. In the prototype conventional two-coil link, the proposed method increased the power amplifier plus inductive-link efficiency from 4.8% to 16.5% at ( RL = 1\, kW, d23 = 3\,cm), and from 23% to 28.2% at (RL = 100\,{\Omega}, d23 = 3\,cm) after 11% change in the resonance capacitance, while delivering 168.1 mW to the load (PDL). [ABSTRACT FROM PUBLISHER]

This paper proposes an optimal design method of modular multilevel converter (MMC) levels to approach the reasonable compromise between accuracy and computational efficiency. The entire procedure is benchmarked by a Thévenin equivalent 451-level MMC model. First, the calculation method of the critical maximum simulation time step is proposed to faithfully represent each voltage level of the staircase waveforms. Second, the previously developed improved analytic hierarchy process is adopted to integrate the relative errors of all the main electrical parameters into one comprehensive relative error at each MMC level. Third, the steady state, ac, and dc transient state relative error results as well as the central-processing unit times of all models are normalized and curve fitted based on the benchmark model. Finally, the optimal MMC level is obtained by the plotted curves and the given subjective weights considering the accuracy and efficiency. And the effectiveness and robustness of the proposed method are validated by various simulation scenarios on PSCAD/EMTDC. [ABSTRACT FROM PUBLISHER]

Switching of logic gates is often responsible for significant power supply noise. Predicting the jitter resulting from the power supply noise can be critical to analyze the proper operation of high-speed devices. The statistical characteristics of jitter, such as the mean standard deviation of jitter, can be used to place a meaningful bound on the worst-case timing margin and to estimate the bit error rate. While the statistical characteristics of the noise can be found through simulations of many input logic vectors, such simulations require significant computational effort and require methods for choosing suitable data vectors. Vectorless methods allow rapid analysis of switching without using predefined input data and can be used to understand which portions of the logic circuit contribute most to the noise. In this paper, methods using vectorless techniques are presented to predict the mean and standard deviation of the power supply noise on the printed circuit board (PCB), and the mean and standard deviation of the resulting peak-to-peak jitter in a driver on the same PCB. In experiments, the techniques were able to predict the average and standard deviation of the peak power supply noise on the PCB with 2% and 8% error, respectively, and of the peak-to-peak jitter with 21% error, which is sufficient for predicting how a specific logic design might impact jitter, and for proposing means to minimize that impact. [ABSTRACT FROM AUTHOR]

Most investigations of all spin logic (ASL) have been based on the monodomain approximation of magnetization switching. The sensitive and stochastic nature of spin transfer torque (STT) switching creates pressing requirements for analyzing ASL from a micromagnetic perspective also. Hence, in this paper, ASL is studied from a micromagnetic perspective by developing a simulation framework that can capture diffusive spin transport. The spin transport model is calibrated from the existing experimental results on nonlocal spin valve measurements. Then, using this framework, STT switching is studied for input–output nanomagnets with in-plane and perpendicular magnetic anisotropy for ASL devices (ASLDs). Precisely defined architecture and design constraints for such input–output nanomagnets are presented. Further, a previously proposed switching mechanism by driving the nanomagnet into a metastable state is also incorporated into micromagnetic framework. Using the aforementioned mechanism, the critical current required for STT switching can be reduced to as low as 20 $\mu $ A. Moreover, the graphene channel ASLD using tunnel contact at the injector is demonstrated for copy and invert logic operations. [ABSTRACT FROM AUTHOR]

Due to the repeated switching, the detailed switch-level models of electrical machines coupled with power-electronic converters are computationally expensive and hard to linearize for small-signal frequency-domain analysis. Average-value modeling (AVM) has become an effective tool for small-signal analysis of power electronic systems and time-domain transient studies where the details of switching are not important and can be neglected. Recently, a parametric AVM (PAVM) approach has been developed for machine/diode rectifier systems. This paper extends the parametric approach to the machine/thyristor-controlled-rectifier systems, where the thyristor firing may be referenced to either the line voltages or the rotor position. An analytical average model for this system is also developed based on the recently proposed constant-parameter voltage-behind-reactance synchronous machine model. The new PAVM is compared against the original switching system, as well as the analytical AVM. It is shown that the PAVM can accurately predict both small-signal characteristics and large-signal transients of the original switching system in light and heavy modes, which represents an advantage over the analytical models which are typically implicit. [ABSTRACT FROM AUTHOR]

This paper derives a circuit-level analytical model for describing the mechanism of the spurious triggering pulse in the gate-source voltage of the synchronous MOSFET (SyncFET) in the synchronous buck converter. The model takes into account not only the parasitic capacitances and inductances of the control MOSFET (CtrlFET) and the SyncFET, but also the reverse recovery characteristics of the body diode of the SyncFET. An exhaustive investigation into the impact of all these factors on the spurious triggering pulse is conducted. The spurious triggering pulse can be attributed to two factors. The first one is the positive gate voltage caused by the displacement current through the gate-drain capacitance of the SyncFET, due to the increase in the drain-source voltage. The second one is the negative source voltage caused by the voltage drop across the source inductance of the SyncFET, due to the decrease in the drain current. It is discovered that the gate impedance of the SyncFET would exert different influence on the magnitude of the spurious triggering pulse, depending on the contributions of these two factors. Experimental results affirm that variation in the magnitude of the spurious triggering pulse with each parasitic element can be correctly inferred by the proposed model. Design guidelines for enhancing spurious turn-on immunity are advanced. [ABSTRACT FROM AUTHOR]

Resistive switching memory (RRAM) relies on the voltage-driven formation/disruption of a conductive filament (CF) across a thin insulating layer. Due to the 1-D structure of the CF and discrete nature of defects, the set and reset states of the memory device generally display statistical variability from cycle to cycle. For projecting cell downscaling and designing improved programming operations, the variability as a function of the operation parameters, such as the maximum current in the set process and maximum voltage in the reset process, need to be evaluated and understood. This paper addresses set/reset variability, presenting statistical data for HfOx-based RRAM and introducing a physics-based Monte Carlo model for switching statistics. The model can predict the distribution of the set state as a function of the compliance (maximum) current during set and distribution of the reset state as a function of the stop (maximum) voltage during reset. Numerical modeling results are finally presented to provide additional insight into discrete fluctuation events. [ABSTRACT FROM AUTHOR]

An architecture of multiple-integrated converter modules sharing an unfolding full-bridge inverter with a pseudo dc link (MIPs) is proposed for grid-connected photovoltaic systems in this paper. The proposed configuration can improve the power conversion, the control circuit complexity, and the cost competitiveness. The proposed MIP is composed of distributed flyback dc–dc converters (DFCs) and an unfolding full-bridge inverter with an ac filter. The DFCs can eliminate the shading effect by using the individual maximum power point tracking. In conventional flyback-type single-phase utility-interactive inverters, discontinuous conduction mode and boundary conduction mode are popular because of the inherent constant current-source characteristics more desirable for grid connection and of the simple procedures for the controller design. However, the operating mode suffers from a large current stress of the circuit components, which leads to the low power efficiency. To avoid this, the DFCs operate under continuous conduction mode that allows reduced current stresses and increased power efficiency, as well as low material cost. The current control loop of the converters employs primary-side regulation contributing to improvement of dynamics as well as the cost reduction significantly due to the elimination of the high-linearity photocoupler device. Development of a new dc-current loop that maintains the level of dc-current injection into the grid within the levels stipulated by IEEE 1547 will be dealt as well. The performance validation of the proposed design is confirmed by experimental results of a 200-W hardware prototype. [ABSTRACT FROM PUBLISHER]

Existing power system planning software is not capable of simulating large numbers of contingencies that involve bus mergers and bus splits without cumbersome modifications to planning models either manually or through scripting. This means that some of the events that can occur in a bulk power system are not studied in detail prior to real-time operation. This paper proposes the use of a unified network applications framework for planning contingency analysis capable of incorporating contingencies that involve arbitrary configurations of switching devices. The method handles any type of bus split or bus merger events automatically without requiring case conversion or modification. This drastically simplifies the tabulation of results of complex contingencies and makes potential unsecure system conditions visible during the planning stage. The efficiency of the algorithm is demonstrated in large-scale ISO models that incorporate full-topology switching modeling, and it is shown to be at least ten times faster than scripting. The proposed method hence supports direct comparison of planning and real-time grid security assessment evaluation, providing full temporal interoperability between offline contingency analysis and real-time security assessment. [ABSTRACT FROM PUBLISHER]

The resistive random access memory (RRAM) crossbar array has been extensively studied as one of the most promising candidates for future high-density nonvolatile memory technology. However, some problems caused by circuit and device interaction, such as sneak leakage paths, result in limited array size and large power consumption, which degrade the array performance significantly. Thus, the analysis on circuit and device interaction issue is imperative. In this paper, a simulation method is developed to investigate the critical issues correlated with the interaction between devices and the circuit. The simulations show that a large off/on ratio of resistance states of RRAM is beneficial for large readout margin (i.e., array size). The existence of the selector connected in series with an RRAM device can eliminate the need for high Ron resistance, which is critical for the array consisted of only RRAM cells. The readout margin is more sensitive to the variation of Ron and is determined by the nonlinearity of the I–V characteristics of RRAM, whereas the nonlinear characteristics of the selector device are beneficial for a larger readout margin. An optimal design scheme for turn-on voltage and conductance of the selector is proposed based on the simulation. [ABSTRACT FROM PUBLISHER]

In this paper, a physics-based high-frequency (HF) model of switching power converters including the insulated gate bipolar transistor (IGBT) unit cells, heat sink, and connective printed circuit board (PCB) traces combined in a single electrical circuit is presented. The IGBT model includes the HF stray components superimposed on the well-known Hefner IGBT model. The HF components were calculated using a 3-D quasi-static finite element (3-D FE) analysis. The proposed complex model of the IGBT was verified both numerically and experimentally at different switching frequencies. The computed IGBT model was used in a low–high frequency model of a motor-drive system, and the common mode ground current was experimentally verified showing excellent results. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on the influences of parasitic elements on the MOSFET switching performance. A circuit-level analytical model that takes MOSFET parasitic capacitances and inductances, circuit stray inductances, and reverse current of the freewheeling diode into consideration is given to evaluate the MOSFET switching characteristics. The equations derived for emulating MOSFET switching transients are assessed graphically, which, compared to results obtained merely from simulation or parametric study, can offer better insight into where the changes in switching performance lie when the parasitic elements are varied. The analysis has been successfully substantiated by the experimental results of a 400 V, 6 A test bench. A discussion on the physical meanings behind these parasitic effect phenomena is included. Knowledge about the effects of parasitic elements on the switching behavior serves as an important basis for the design guidelines of fast switching power converters. [ABSTRACT FROM AUTHOR]