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This paper presents a simple pulse width modulation algorithm for control of an ultracapacitor based energy storage system used for source and load support applications. As opposed to dual loop control philosophy that is widely used for backup applications, this paper presents a simple single loop current control that is only useful for controlling the ultracapacitor based DC/DC converters used in source and load support applications. The proposed PWM blocking method necessitates the DC/DC converter to operate in five states and takes into consideration the essential operational limits associated with the ultracapacitors. The performance of the proposed algorithm is verified experimentally using a 24 V laboratory prototype setup. Further, the shortcomings of dual loop control when applied to source and load support applications are demonstrated. [ABSTRACT FROM AUTHOR]

Magnetic random-access memory (MRAM) is a promising memory technology due to its high density, non-volatility, and high endurance. However, achieving high memory fidelity incurs high write-energy costs, which should be reduced for large-scale deployment of MRAMs. In this paper, we formulate a biconvex optimization problem to optimize write fidelity given energy and latency constraints. The basic idea is to allocate non-uniform write pulses depending on the importance of each bit position. The fidelity measure we consider is mean squared error (MSE), for which we optimize write pulses via alternating convex search (ACS). We derive analytic solutions and propose an alternating water-filling algorithm by casting the MRAM’s write operation as communication over parallel channels. Hence, the proposed alternating water-filling algorithm is computationally more efficient than the original ACS while their solutions are identical. Since the formulated biconvex problem is non-convex, both the original ACS and the proposed algorithm do not guarantee global optimality. However, the MSEs obtained by the proposed algorithm are comparable to the MSEs by complicated global nonlinear programming solvers. Furthermore, we prove that our algorithm can reduce the MSE exponentially with the number of bits per word. For an 8-bit accessed word, the proposed algorithm reduces the MSE by a factor of 21. We also evaluate MNIST dataset classification supposing that the model parameters of deep neural networks are stored in MRAMs. The numerical results show that the optimized write pulses can achieve 40% write-energy reduction for the same classification accuracy. [ABSTRACT FROM AUTHOR]

In this paper, we present two new families of APN functions. The first family is in bivariate form $\big (x^{3}+xy^{2}+ y^{3}+xy, x^{5}+x^{4}y+y^{5}+xy+x^{2}y^{2} \big)\,\,\vphantom {_{\int _{\int }}}$ over ${\mathbb F}_{2^{m}}^{2}$. It is obtained by adding certain terms of the form $\sum _{i}(a_{i}x^{2^{i}}y^{2^{i}},b_{i}x^{2^{i}}y^{2^{i}})$ to a family of APN functions recently proposed by Gölo&gcaron;lu. The $\vphantom {_{\int _{\int }}}$ second family has the form $L(z)^{2^{m}+1}+vz^{2^{m}+1}$ over ${\mathbb F}_{{2^{3m}}}$ , which generalizes a family of APN functions by Bracken et al. from 2011. By calculating the $\Gamma $ -rank of the constructed APN functions over ${\mathbb F}_{2^{8}}$ and ${\mathbb F}_{2^{9}}$ , we demonstrate that the two families are CCZ-inequivalent to all known families. In addition, the two new families cover two known sporadic APN instances over ${\mathbb F}_{2^{8}}$ and ${\mathbb F}_{2^{9}}$ , which were found by Edel and Pott in 2009 and by Beierle and Leander in 2021, respectively. [ABSTRACT FROM AUTHOR]

In a recent work, Beierle, Brinkmann and Leander presented a recursive tree search for finding APN permutations with linear self-equivalences in small dimensions. In this paper, we describe how this search can be adapted to find many new instances of quadratic APN functions. In particular, we found 12,921 new quadratic APN functions in dimension eight, 35 new quadratic APN functions in dimension nine and five new quadratic APN functions in dimension ten up to CCZ-equivalence. Remarkably, two of the 35 new APN functions in dimension nine are APN permutations. Among the 8-bit APN functions, there are three extended Walsh spectra that do not correspond to any of the previously-known quadratic 8-bit APN functions and, surprisingly, there exist at least four CCZ-inequivalent 8-bit APN functions with linearity 27, i.e., the highest possible non-trivial linearity for quadratic functions in dimension eight. [ABSTRACT FROM AUTHOR]

When a superconductor is exposed to an AC magnetic field whilst carrying a constant DC transport current, a DC electrical resistance can be observed, commonly referred to as “dynamic resistance”. This dissipative effect can play a critical role in many potential high-temperature superconducting (HTS) applications, especially for the AC-field-actuated HTS switch, which is the key component in the HTS transformer-rectifier flux pump (TRFP). The characteristics of the HTS switch determine the performance and reliability of TRFP. In this paper, we report a numerical study of a new HTS switch design made of series-connected YBCO stacks. This study aims to obtain insights into the characteristics of dynamic resistance and power loss, including their relationships with the amplitude and the frequency of the AC magnetic field. The energy conversion efficiency of the HTS switch is also investigated. This work will help design a high-performance AC-field-actuated HTS switch. [ABSTRACT FROM AUTHOR]

This paper proposes a control method for a switching power converter. This converter is connected to a dc-link of a dc microgrid system via an LC input filter. This control method is based on a Lyapunov stability analysis; all state variables are acquired for evaluating stability analysis, including the output current for calculating the load resistance. To reduce a number of sensor counts, the input current is estimated. Moreover, loss occurrence in the converter is observed to reduce static errors of the controlled state variables, especially the output voltage. The losses are modeled as a series input voltage source observed from the dc–dc converter and a parallel current source. The latter enables us to eliminate the output current sensor. Using information from the estimated current source, a load resistance can be calculated. A Lyapunov function candidate is chosen to ensure that the system, including the observer, operates in a stable manner. Based on evaluating the time-derivative of the chosen Lyapunov function, we obtain the switching command that makes the system operate stably in each sampling cycle. In this paper, the proposed technique is applied to a boost converter. The simulation and as well experimental results validate the proposed control. [ABSTRACT FROM AUTHOR]

This paper has introduced two important indexes, turn-off surge voltage (TSV) on power switch and peak positive pole potential (PPPP) of storage batteries, which can be used to evaluate switching transient process of high-voltage energy storage system. Research on them is of great significance to power switch choice and high-voltage isolation design in engineering applications. Power switch response process at the turning off moment and transient process in freewheel stage have been analyzed by the established small-signal model of single power switch; then, a power switch test platform for hybrid energy storage system was built to verify it. Taking pulsed-power supply charging device with a novel inductor of low resistance and high inductance as a research object, this paper has analyzed dynamic process of the TSV and the PPPP at the turning off moment through establishing state space model of the whole system. Comparison shows that the numerical curves match the simulated curves well. Finally, the exactness of the employed model has been further verified in two pulse capacitor charging experiments. [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]

In this paper, the third quadrant behavior of a high-voltage superjunction mosfet (SJ-FET) in cascode configuration (CC) with a low-voltage silicon mosfet is deeply studied by means of an analytical model and experimental data. The third quadrant dynamic behavior of the SJ-CCs is compared to the standalone counterparts by evaluating their reverse recovery time (tRR), reverse recovery peak current (IRRM), and reverse recovery charge (QRR). An analytical model and experimental results show that the SJ-CC avoids or mitigates the activation of the SJ-FET body diode during the third quadrant operation. As a consequence, the SJ-CC strongly improves the widely used figure-of-merit RON·QRR, which considers the on-state resistance of the transistors (RON). In addition, the results obtained using an SJ-CC are similar or better than those achieved by SJ-FETs with enhanced reverse recovery (i.e., irradiated SJ-FETs). This paper also includes a comparison with commercial wide bandgap switches, concluding that the RON·QRR value provided by the SJ-CC is around eight times higher than that provided by a commercial GaN cascode. [ABSTRACT FROM AUTHOR]

To effectively solve the crosstalk issue in high-density crossbar array (CBA), high rectifying characteristics should be introduced in the resistance random-access memory (ReRAM) device, and in-depth understanding of the affecting factors on rectifying properties is essential for the large-scale application of ReRAM. In this paper, a high-performance self-rectifying device with CMOS compatible Pd/HfO2/TaOx/Ta structure was demonstrated in a 1-kb CBA. Forming-free, self-compliance, and high uniformity characteristics were successfully achieved. By modulating the thickness of the HfO2 rectifying layer, the rectifying ratio of device could be achieved as high as $\sim 2\times 10^{\textsf {3}}$ under ±3 V at low-resistance state (LRS). It was also experimentally confirmed that the selected unit cell in high-resistance state (logically the “ OFF” state) was stably readable when it was surrounded by unselected LRS (logically the “ ON” state) cells, in an array of up to $32 \times 32$ cells. Furthermore, a model based on interfacial barrier modulation and defects trapping/detrapping was proposed to elucidate the impact of the dielectric thickness on the self-rectifying characteristics of the device. The results presented in this paper provide a great potential for selector-free high-density memory applications. [ABSTRACT FROM AUTHOR]

This paper proposes unconventional control techniques for a portable power supply consisting of electric double-layer capacitors (EDLCs), a dc–dc converter, and a low-impedance load such a plasma load. Between the EDLCs and the plasma load consuming high power, a dc–dc converter is required to control the output voltage from the rapidly decreasing voltage of EDLCs. In addition, the dc–dc converter should maintain a set point by responding to arcs occurred in plasma process. This paper proposed hybrid analog and digital controls for a nonideal boost converter which was setup by theoretical analysis. The proposed system is verified with experiment and simulation. As a result, the proposed control method can maintain the constant output voltage longer than a traditional analog pulsewidth modulation control. [ABSTRACT FROM AUTHOR]

In this paper, the NbOx, which was regarded as a promising material based on its insulator–metal transition (IMT) effects, was applied as the switching layer of the device. The threshold switching characteristics were comprehensively investigated with particular emphasis on temperature dependence. The conduction mechanism for high-resistance state (HRS) was fitted and verified to be Schottky emission. With the increase in temperature, the fitting results demonstrated that the Schottky barrier decreased, leading to a reduction in the resistance of HRS. Furthermore, according to Fourier’s law of heat conduction, the fluctuation range of temperature was smaller, causing a narrow distribution of the threshold voltage as the operating temperature increased. In addition, the increasing temperature caused high energy of electrons, which would induce an IMT more easily, leading to a lower threshold voltage. This paper provided the promise for improving the thermal stability of selected devices. [ABSTRACT FROM AUTHOR]

This paper presents a study of the losses in the integrated buck–flyback converter (IBFC) used as high-power-factor LED driver. The aim of the study is to investigate the possibilities of increasing the efficiency of the IBFC converter. The procedure of the improvement is done by obtaining the equations of the current through each component in terms of converter parameters. The current is found in an average value or rms value, depending on the type of the parasitic component, whether it is modeled by a parasitic forward voltage source or by a parasitic resistance, respectively. Using these equations and the parasitic model, the losses of each element of the converter are estimated. This paper proposes a technique to increase the efficiency of the IBFC by redesigning the converter parameters. Furthermore, this paper presents a case of study with a step-by-step efficiency enhancement process of an existing driver. The driver is operating under universal input conditions, and 38 V output, supplying an LED luminary of 26.5 W. The new design shows an improvement of the efficiency from 82% in the old design to 89% in the proposed one. Moreover, the new design shows an improvement in the power factor and the THD and a 50% reduction in the output current ripple. Furthermore, a reduction in the number of components has been achieved, as it is found by the analysis that by adjusting the converter parameters, one diode can be removed. Finally, the presented methodology is explained in detail so that it can easily be applied to other dc–dc converters. [ABSTRACT FROM AUTHOR]

This paper presents the design and construction of a sample of Marx pulsed generator based on boost converter (BC) pulse-forming networks (BCPFNs). BCPFN is used instead of the conventional Marx floors for constructing this pulsed generator. BCPFN is carried out by connecting inductors and capacitors in series and parallel modes, respectively, by using solid-state switches, and during this procedure the pulsed generator converts to BC temporarily and increases the voltage of capacitors uniformly to a considerable value. This technique causes an increase in the discharging voltage level to the load that is many times more than its dc voltage source by charging the capacitors to a greater level. In order to take advantage of the benefits of Marx generator and PFN, this paper suggests a new circuit with the minimum number of switches. It means, to compose BCPFN and Marx, we have tried to design the circuit with fewer switches and instead of it we have achieved our desired performance with changing the operating mode in the states of BC, PFN, BCPFN, and BCPFN Marx. The results are simulated with MATLAB software. At the end, the experimental results of the construction of the above-mentioned system at low-power levels are presented, and the topology’s accuracy is proved by comparing them to the results of simulation. [ABSTRACT FROM AUTHOR]

The introduction of metal nanocrystals (NCs) has been confirmed to improve electrical uniformity of oxide-based resistive random access memory (RRAM) devices significantly; however, the current reports do not systematically elucidate the relationship between the size/distribution of NCs and the electrical uniformity of RRAM devices. In this paper, we focused on the impact of metal NCs size and areal density on the resistive switching (RS) performances of oxide RRAM by atomic layer deposition (ALD) based on the experimental results and theoretical calculation. The dependence of ALD cycles of 50–130 during Pt or CoPtx NCs growth on the RS parameters of Al2O3 or HfO2 memory units has been evaluated systematically. The RRAM embedded Pt or CoPtx NCs shows the trends: with increasing ALD cycles, the forming voltage, set/reset voltage, the resistance in off and on state, and ${R}_{ \mathrm{\scriptscriptstyle OFF}}/{R}_{ \mathrm{\scriptscriptstyle ON}}$ ratio entirely first decrease, then flatten, and increase later with a minimum value at about 100 cycles. Although all metal NCs with various sizes enhance the electric field strength compared to at the planar region, only metal NCs with proper NCs size and areal density (9 nm/6– $10\times 10^{\textsf {11}}$ /cm2 in this paper) can effectively produce stronger localized electric field at the tip of metal NCs, leading to optimal RS behavior. [ABSTRACT FROM AUTHOR]

Dual-comparison one-cycle control for the bidirectional power flow in single-phase grid-connected converters is proposed in this paper. Advantages of dual-comparison one-cycle control when compared to conventional one-cycle control is that it does not give any steady-state dc offset, no light-load instability, and implements unipolar pulsewidth modulation without having to sense the grid voltage. Addition of a fictitious current term, which is generated from the gating signal of one of the active devices, using a bandpass filter, enables the bidirectional power flow. The quality factor of the bandpass filter is shown to impact the total harmonic distortion in current, fundamental displacement angle, and steady-state dc offset. The optimal value of a quality factor, obtained with aid of simulations, gives a superior performance. The current drawn or injected into the grid is seen to lag the grid voltage. The reason for a nonunity displacement power factor is analyzed and a compensation to achieve a unity displacement power factor is also proposed in this paper. Detailed simulation and experimental studies are carried out to validate the proposed control and the high performance that can be obtained. [ABSTRACT FROM AUTHOR]

Superjunction MOSFETs in cascode configuration with low-voltage silicon MOSFETs are evaluated in this paper. The proposed structure combines the good switching performance provided by the cascode configuration with the benefits of the silicon technology such as its robustness, maturity, and low cost. This paper aims to explain and to demonstrate the reduction of switching losses of superjunction MOSFETs in cascode configuration with respect to their standalone counterparts (directly driven). A detailed simulation analysis of power loss contributions is carried out under hard-switching operation. Moreover, experimental evidence is provided using a boost converter (100–400 V) operating in continuous conduction mode for different switching frequencies (100–400 kHz) and output power levels (180–500 W). [ABSTRACT FROM AUTHOR]

In some conditions, the flux in the core of current transformers (CT) increases. If this increase in flux leads to saturation of the protective core, it can create a lot of problems in power system protection. One of the hardware solutions to prevent the occurrence of core saturation in CT is the fixed switched resistor demagnetization method. Due to disadvantages such as dependence on CT parameters and inefficiencies in severe core saturation, the use of this method has not been expanded. This paper proposes a new method to improve the fixed switched resistor demagnetization method. In the proposed method, instead of using a fixed resistor in the circuit topology, an adjustable resistor with an auxiliary transformer is used. In the previous method, the control process is based on flux estimation from the secondary terminal voltage. The control process in the proposed method is based on the second derivative of CT secondary current. To verify the effectiveness of the suggested method, first simulation is done using COMSOL and MATLAB softwares and then all necessary electronic and control circuitry are designed and built. Experimental test is carried out on a 20 kV- 500/5 A CT. The simulation and experimental results show that this method prevents the CT from saturation in case of short circuit faults. The main advantages of this method are independent to CT parameters and efficient in severe core saturation. [ABSTRACT FROM AUTHOR]

This paper develops a novel voltage equalizer by combining wireless power transfer (WPT) and a voltage multiplier (VM) for series-connected energy storage cells. The physical isolation achieved by WPT can offer several unique benefits that traditional equalizers can hardly provide. In this paper, the characteristics of a multiple-output VM are analytically discussed and used to develop an equivalent one-output VM model. Based on this model, parameters of the WPT system are properly designed. The proposed design methodology can achieve a single-switch voltage equalizer without feedback control, which dramatically decreases the circuit complexity and cost. Moreover, this methodology can naturally ensure a robust system under small coil misalignment. In the experiment, the proposed system is built to balance four series-connected ultracapacitor modules. The system efficiency is 72.8% at a load power level of 10 W. [ABSTRACT FROM PUBLISHER]

Fast and detailed calculations of harmonics, generated by three-phase uncontrolled rectifiers with finite dc smoothing, can be performed by using detailed analytical procedures (DAPs). Several DAPs are developed for continuous- and discontinuous-conduction modes (CCM and DCM) when balanced operation of the system is assumed. The authors of this paper have recently proposed a new DAP (model 1a) in which nonideal conditions, such as unbalances and even harmonic voltages on the ac side, are taken into account. However, only CCM is assumed in model 1a. The main objective of this paper is to overcome this limitation of model 1a so that a new DAP (model 1b) for DCM is presented, which is capable of considering unbalanced operation. Moreover, the boundary of the DCM is also estimated for model 1b under nonideal conditions. [ABSTRACT FROM PUBLISHER]

Digital current controllers have the key impact on the performance of grid-side converters and ac drives. The voltage disturbances are commonly suppressed by enhancing the controller with an inner active resistance feedback. In cases where the switching noise and parasitic oscillations introduce sampling errors, conventional sampling is replaced by the oversampling-based error-free feedback acquisition which derives the average of the measured currents over the past switching period. The time delay introduced into the feedback path creates difficulties in designing the current controller with the active resistance. In this paper, we introduce a novel structure of the current controller, which includes the error-free sampling and the active resistance feedback. Devised structure improves the disturbance rejection by extending the range of permissible values of the active resistance. Controller structure is based on the internal model principles, and it maintains the input step response unaffected. This paper comprises analytical design, the gain setting procedure, computer simulation, and experimental results obtained from an experimental setup with a three-phase inverter, digital controller, and a permanent-magnet synchronous motor. [ABSTRACT FROM PUBLISHER]

Negative capacitance FETs (NCFETs) have attracted significant interest due to their steep-switching capability at a low voltage and the associated benefits for implementing energy-efficient Boolean logic. While most existing works aim to avoid the ID – VG hysteresis in NCFETs, this paper exploits this hysteresis feature for logic-memory synergy and presents a custom-designed nonvolatile NCFET D flip-flop (DFF) that maintains its state during power outages. This paper also presents an NCFET fabricated for this purpose, showing <10 mV/decade steep hysteresisedges and high, up to seven orders inmagnitude, R\text {DS} ratio between the two polarization states. With a device-circuit codesign that takes advantage of the embedded nonvolatility and the high R\text {DS} ratio, the proposed DFF consumes negligible static current in backup and restore operations, and remains robust even with significant global and local ferroelectric material variations across a wide 0.3–0.8 V supply voltage range. Therefore, the proposed DFF achieves energy-efficient and low-latency backup and restore operations. Furthermore, it has an ultralow energy-delay overhead, below 2.1% in normal operations, and operates using the same voltage supply as the Boolean logic elements with which it connects. This promises energy-efficient nonvolatile computing in energy-harvesting and power-gating applications. [ABSTRACT FROM PUBLISHER]

Resistive Random-Access Memory (ReRAM) devices have caught significant research attention as scalable nonvolatile memory technology for high-density data storage in 3-D crossbar architectures. ReRAM devices can switch with low programming voltages (<±1 V) at fast time-scales (≍10–100 ns) that make them an attractive option for not only off-chip data storage but also for on-chip embedded memory applications. ReRAM devices have also been explored for applications as reconfigurable switches in field programmable gate arrays (FPGAs). The random variabilities in the switching performance of ReRAM has been exploited to design Physically Unclonable Function (PUF) for hardware authentication, trust, and security. However, intrinsic vulnerabilities in ReRAM devices and its implications are not well-understood. Therefore, there is an urgent need to understand these so that the ReRAM-based circuits can be made robust against such attacks. This paper discusses our research on understanding the vulnerabilities in ReRAM through experimental studies and its implications on ReRAM based PUF operations. The Process, Voltage, Temperature (PVT) variabilities in ReRAM is experimentally studied and modeled. Some other ReRAM specific vulnerabilities, such as insertion of parasitic capacitances and Trojans by adversaries and its impact on ReRAM switching behavior is discussed. Based on experimental studies, models are created to capture these behaviors in ReRAM. Using these models, a 1 KB array of ReRAM devices in a crossbar architecture and its behavior is simulated. The challenge–response pairs of these ReRAM-based arrays were studied under ideal Trojan free conditions as well as with vulnerabilities models of ReRAM. Potential solutions are then proposed to make the PUF architecture and ReRAM devices more resistant to these vulnerabilities. [ABSTRACT FROM AUTHOR]

This paper deals with assessment of grounding systems impacts on power electronic interfaces. To this end, transient overvoltage and overcurrent are analyzed in different fault situations considering various grounding conditions from the power electronic switches point of view. A new model for a neutral point clamped power electronic interface is presented that is suitable for this assessment. Plenty of simulations are carried out; from their results one can offer some valuable comments regarding ground condition impacts on the transients. It will be confirmed that grounding resistance and structure of dc microgrids have considerable impacts on the transients experienced by power electronic switches. The permissible range of the grounding resistance and the worst states of the switching template from transient voltage and current aspects are determined. By real-time monitoring of the grounding resistance and taking into account the simulations outcomes, one can alleviate transients experienced by the switches and promote fault ride through capability of the converter. Since computational burden of the proposed simple model is relatively low, it is applicable in real-time monitoring of the ground systems in practice. [ABSTRACT FROM AUTHOR]

In this paper, closed-loop control and boundary condition for continuous conduction mode and discontinuous conduction mode of nonisolated inverting N× multilevel boost converter (MBC) are articulated. Inverting N× MBC combines the features of classical boost converter and voltage multiplier to attain inverting N times higher voltage. Consequently, the inverting N× MBC provides a viable solution for high-voltage step-up photovoltaic applications with low voltage rating reactive components and semiconductor devices. The control strategy with saturation limiter is employed to achieve highly stable voltage. The modes of operation, benefits of inverting N× MBC, and key factors for the selection of semiconductor devices and sizing of the reactive components are discussed. Additionally, the effects of reactive components and semiconductor devices on the output voltage are examined. Experimental results of the developed circuit are presented to validate the design of converter, and effectiveness and robustness of the implemented control algorithm for different input and output side perturbations. [ABSTRACT FROM AUTHOR]

This paper proposes a self-synchronizing synchronverter controller design that leverages the addition of a virtual resistance (along with a suitable coordinate transformation) to compute feedback signals during self synchronization prior to grid connection. With respect to analysis, we exploit separation-of-time-scales arguments and develop appropriate reduced-order models, which are well-suited for studying phase-angle and voltage-magnitude self-synchronization dynamics independently. Our work provides analytical justification for the effects of pertinent controller parameters and system initial conditions on self-synchronization dynamics observed empirically in time-domain simulations. As such, it offers practical guidance on favourable parameter-value settings to achieve fast self synchronization, and it yields accurate estimates for self-synchronization times with well-tuned parameters. Through numerical simulations and experiments, we illustrate the efficacy of the proposed controller design and verify the validity of subsequent analyses. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) power electronic devices feature the advantages of fast switching speed, low conduction loss, and reliable operation in high temperature environment, etc. Due to the differences of parasitic parameters and threshold voltage between SiC mosfets and Si mosfets, crosstalk problem is easy to be triggered when SiC mosfets are applied to bridge topologies. In this paper, the crosstalk effect with different parasitic parameters of SiC mosfets is firstly analyzed, and then an improved active crosstalk suppression method for high-speed SiC mosfets is proposed. By using the proposed method, when the crosstalk occurs, the crosstalk voltage will be decreased by reducing the equivalent gate resistance and increasing the equivalent gate-source capacitance in an active way. Consequently, the crosstalk problem can be suppressed without affecting the switching speed. To verify the effectiveness of the proposed method, a prototype of a buck–boost converter is built and the proposed modified gate driver is applied to the half-bridge topology. Comparative experimental study is conducted and the crosstalk voltage is analyzed. The experimental results verify that effective crosstalk suppression is achieved. [ABSTRACT FROM AUTHOR]

Power flow control in multiterminal HVdc (MTdc) grids is essential to restrict operation within permissible limits. A current flow controller (CFC) can achieve this. In this paper, the modeling, control, and simulation of resistive, RC-circuit-based, and capacitive CFCs is carried out. CFC prototypes have been developed and an MTdc grid test-rig has been employed for experimental validation. Results show that all devices achieve an effective power flow management. The impact of CFC deployment in future MTdc grids is assessed on droop-controlled converters. A voltage compensation-based method is proposed to minimize power deviations during unscheduled line current control. A protection scheme has been assessed under faults. [ABSTRACT FROM AUTHOR]

Marx generator using all-solid-state devices has been studied for many years. Higher parameters are always the demand for new applications. Traditional all-solid-state Marx generator can output high voltage due to its series topology, but the current is always limited by the switch. In this paper, a stage-stage paralleled topology of Marx generator for high current has been proposed. Topology structure and driving mode comparison for current balance have been analyzed. The paralleled driving mode for the current balance and the shaping waveform has been proposed. For experiment, a four-stage-four-paralleled Marx generator with metal–oxide–semiconductor field-effect transistors (MOSFETs) has been constructed with output pulses 2.2 kV, 730 A (depending on the load), rise time of 31 ns, fall time of 56 ns, and adjustable pulsewidth from 400 to 800 ns. [ABSTRACT FROM AUTHOR]

The magnetic resonant wireless power transfer (WPT) system with a class E inverter has wide application in mid-range power transmission, especially for several megahertz scenario. However, it is cumbersome for the existing modeling and analysis methods to obtain the analytical solution to the system variables, which limits the evaluation of system characteristic. This paper proposes a nonlinear mathematical model for the WPT system with a class E inverter. The equivalent small parameter method (ESPM) is first adopted to solve the proposed six-order nonlinear model, and symbolic-form steady-state periodic solutions are yielded. During the whole solving process, only three iteration steps are needed for the proposed method. Compared with other existing modeling and analysis methods, the symbolic periodic results acquired by the ESPM exhibit sufficient accuracy by virtue of the combination of more higher harmonics. Meanwhile, the calculation complexity is simplified remarkably. Simulation and available experiments validate the effectiveness and accuracy of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a light, flexible, and yet reliable multiparametric estimation algorithm for grid-connected voltage-source-converter-based systems. This approach combines the nonlinear least squares (NLSQ) fitting algorithm and the steady-state extended harmonic domain (EHD) model to take into account the harmonic effects. The EHD model is used to take advantage of the harmonic content of the electrical signals to provide robustness and improved performance to the NLSQ estimation methodology. In addition, this harmonic formulation reduces the necessity of synchronized measurements. Details of the implementation are provided by an experimental case study, in which the grid equivalent (Thevenin voltage, inductance, and resistance), the ac-side filter (inductance and resistance), and the converter switching and conduction loss resistance are accurately estimated for three different operating conditions. [ABSTRACT FROM AUTHOR]

The degradation of submodule (SM) insulated gate bipolar transistors (IGBTs) in a modular multilevel converter (MMC) can be monitored through their on-state voltages. This paper proposes a scheme to calculate the IGBT on-state voltages at rated current and normal junction temperature. The equations of on-state resistances are established based on Kirchhoff voltage laws (KVL) in one MMC arm for positive and negative current directions separately. The arm current, arm voltage, capacitor voltages, gate signals, and junction temperatures are utilized in the equations, and most of the signals are known for the control system. The dimension of the equation set is reduced to make it solvable based on an assumption that all the on-state resistances of diodes remain equal. In addition, the Kalman filter (KF) is used to improve the stability and accuracy of the calculation results. The calculated results are converted to the normal condition based on the current-voltage (I–V) and resistance-temperature (R–T) characteristics of SM IGBTs and diodes. The scheme is verified by using the simulation of a five-level three-phase MMC model. The errors of the calculated VCE are within 0.3%, and the calculation accuracy is good enough for the estimation of IGBT degradation. Furthermore, the influences of the measurement accuracy and the equal diode voltage assumption on the calculation accuracy are analyzed. The proposed scheme is expected to be applicable in online condition monitoring of SM IGBTs. [ABSTRACT FROM AUTHOR]

The derivation and implementation of the natural switching surfaces (NSS) considering certain parametric uncertainties for a flyback converter operating in the boundary conduction mode is the main focus of this paper. The NSS with nominal parameters presents many benefits for the control of nonlinear systems; for example, fast transient response under load-changing conditions. However, the performance worsens considerably when the converter actual parameters are different from the ones used in the design process. Therefore, a novel control strategy for NSS considering the effects of parameter uncertainties is proposed. This control law can estimate and adapt the control trajectories in a minimum number of switching cycles to obtain excellent performances even under extreme parameter uncertainties. The analytical derivation of the proposed adaptive switching surfaces is presented together with simulations and experimental results showing adequate performance under different tests, including comparisons with a standard PI controller. [ABSTRACT FROM AUTHOR]