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Solid-state dc circuit breakers (DCCBs) are increasingly employed across all power levels, including MVdc networks. Seamless integration of DCCBs into medium voltage direct current (MVdc) networks is challenging due to the diverse voltage and power levels. Furthermore, the limited current and voltage capability of semiconductor devices limits the full integration of solid-state DCCBs for MVdc applications. Series and parallel-connected insulated-gate bipolar transistor (IGBT) arrays can be employed to match the current and voltage levels required. However, with passive gate drives, devices may fail due to non-homogeneous current and voltage distribution across IGBTs. Closed-loop active gate drives (AGDs) provide a solution to overcome this. In the proposed standardized-active switching module (ASM) scheme, IGBTs are equipped with AGDs with status feedback. This control method enables the IGBTs to follow a defined current/voltage trajectory during the switching rather than being guided by the inherent characteristics of the device. Hence, with the ability to control dynamic current and voltage, an additional degree of freedom is enabled to connect several ASMs in series and parallel. DCCB architecture based on Standardized-ASMs is proposed as a flexible protection solution for MVdc networks. This paper describes the developed AGD scheme and behavioral analysis of the AGD-based ASMs. Experimental results show the dynamic voltage and current slope control capability of the proposed standardized ASMs. Finally, this paper assesses the ASM-based DCCB architecture for MVdc networks. An ASM-based DCCB prototype was developed and tested to verify the voltage and current sharing capability of modular ASMs in the proposed DCCB architecture.

In recent years, adaptive network-based fuzzy inference systems (ANFIS) applied in various engineering fields have demonstrated their ability to combine the learning capability of artificial neural networks and the representation of fuzzy inference systems, achieving promising results, and attracting the research community's interest. This article provides a valuable overview of ANFIS applications. Focusing on the field of electronic engineering, in particular for power electronics applications, the use of ANFIS has proven to be a very effective and reliable tool for applications requiring maximum power point tracking and power quality improvement. For this reason, this article presents an analysis of the review of 59 papers published between 2013 and 2023, of particular interest the applications of ANFIS for power quality improvement and harmonic content decrease in multilevel converters. This article applied a methodology for the systematic literature review that included identification, selection, eligibility, and inclusion criteria that allowed the selection of publications from the various relevant journals and databases consulted. Subsequently, the surveyed publications were analyzed and classified, highlighting the applications, characteristics of the ANFIS employed, their training algorithms, and the platforms or digital cards used. After analyzing the information from the surveyed papers, it can be concluded that using ANFIS has obtained promising results in improving inverter performance and power quality indexes in the face of variations. ANFIS offers flexibility and adaptability by performing adaptive and real-time control by continuously adjusting the inverter operation.

Due to the extensive role of nonisolated high step-up dc–dc converters (NHSDC)s in industrial applications and academic research works, many of these pulsewidth modulation converters have been presented in recent years. For each of these NHSDCs, some claims are introduced to verify its capabilities and features, which have been investigated in some review papers with different frameworks. Dissimilar to previous review papers, which have focused on the classification and derivation of voltage boosting techniques, this article aims to evaluate the converters from various topological and operational points of view and determine the superiority of each technique and converter according to applications. Some of these metrics are voltage gain, stresses, ripple, cost, power density, weight, size, control complexity, and components count, which lead to a comprehensive comparative study. Then, as the main purpose of this article, the effectiveness of these metrics is assessed to show how well they can lead us to fair comparison results. Moreover, some new figures of merit are proposed in this article to provide a helpful guideline in power electronic converters comparison studies. Finally, the feasibility discussion of single- and multiobjective figures of merit is followed by a general practical conclusion and outlook about the NHSDC structures.

Multiresonant controllers are widely used in the current control of grid-connected converters due to their accurate tracking of reference sinusoidal signals containing high harmonic counts. However, the performance of multiresonant controllers relies heavily on the suitability of the parameter design. In this paper, a generalized multiresonant controller that unifies various existing resonant controllers is proposed, which achieves the decoupling of the proportional terms, eliminates the need for online operation of trigonometric functions, and obtains a more extensive range of regulation capability. Furthermore, a new multioptimized parameter tuning method that considers several performance indexes is proposed to utilize the generalized resonant controller's performance fully. Finally, based on the proposed method, a generalized multiresonant controller is designed for $ {\bm {L}}$-type and $ {\bm {LCL}}$-type grid-connected inverters, respectively, demonstrating the universality of the proposed approach. Simulation and experimental results validate the effectiveness of the proposed method.

Inductive power transfer (IPT) systems that are insensitive to air gaps are preferable for wirelessly charging of electric vehicles over different air gaps. To fulfill this need, this paper proposes a six-coil hybrid IPT system that uses particle swarm optimization to maintain constant voltage output over a wide variation of air gap and load. It employs two orthogonal DD coils and one quadrature (Q) coil pad structure on each side to achieve stable and load-independent output voltage with high tolerance to air gap variation. A detailed mathematical model with theoretical analysis is presented for the proposed system, which can be operated safely even under no load conditions. To demonstrate the applicability of the proposed concept, experimental results of a prototype system are presented. The results indicate that the proposed system can operate under simultaneous variations of air gap from 20 mm to 140 mm (the coupling factor varies from 0.1–0.6) and load from 80 Ω to 400 Ω while maintaining the output voltage within 5% and at maximum dc–dc efficiency of 96%.

The problem of voltage restoration and current balancing has been a hot topic in the study of DC microgrids (MGs), and how to engineer a secondary controller to solve the conflict between these two is the concern of this paper. With the above consideration, an optimal distributed data-driven secondary control strategy is proposed, relying entirely on the input and output data of DC MGs. The proposed framework completes the design of a secondary control strategy based on a data model for the first time, which incorporates the physical coupling relationship between voltage and current into the controller design and is independent of the global circuit parameters and topology information. By means of a proposed cost function, the designed control strategy enables DC MGs to achieve better output current quality at steady state. Unlike the existing schemes based on average voltage observer, this paper resorts to a combination of limiting the voltage reference value generated by the secondary controller and a current cooperative strategy based on the data model to achieve an easy-to-use trade-off between the two objectives of voltage regulation and current sharing. Then, an analytical model of a closed-loop DC MG system under the proposed control scheme is developed, and the analysis of stability and consensus of weighted output current is given accordingly. Finally, the proposed control strategy is tested on a hardware DC MG system with solar panels and a maximum power point tracking (MPPT) controller.

Predictive maintenance scheduling of modular-multilevel-converters (MMCs) requires estimations of the failure probabilities of MMCs during a period of time in the future. Particularly, the predicted future failure probabilities are influenced by two main factors, the mission profiles of the MMCs and the maintenance decisions on the MMCs during the prediction period. This paper proposes a failure probability prediction model (FPM) for MMCs by considering these two factors. First, the expectations of the failure probabilities of the components for all the scenarios of mission profiles are obtained. Second, in predictive maintenance scheduling problems, the decisions to perform the maintenance actions are represented by binary variables. When the number of submodules is very large, using the binomial probability form currently used in reliability engineering to express the “r-out-of-n” failure probability of arms of the MMCs is intractable. Thus, this paper proposes a tractable form (T-form) in FPM by observing that the submodules on one arm are homogeneous. Furthermore, an approximation method, i.e., clustering and assignment (C&A), is proposed to reduce the computation times for calculating the parameters needed by the proposed T-form. Then, we perform a case study that assesses the accuracy and computation time of the C&A approach. The results show that the accuracy of the C&A approach is high and that the computation time is reduced significantly compared with the accurate method. We also show that the computation time for solving the predictive maintenance scheduling problem can be reduced hugely by using the T-form instead of the binomial probability form.

Induction heating technology provides efficient and reliable heating processes that outperform other classical heating methods based on fossil fuels or resistive heating. Among its many industrial, domestic, and biomedical applications, domestic induction heating appliances are a popular choice due to these advantages. This technology requires high-performance and cost-effective inverters that take most of the power devices and the converter topology. Depending upon the desired performance and output-power range, different power converters are employed. However, currently, most platforms rely on the well-known series resonant half-bridge topology. Single-switch topologies offer a cost-effective implementation but are limited to the low-cost low-performance markets due to their limitations in terms of output power and power control. In this context, this paper proposes a high-performance dual-output quasi-resonant inverter for modern induction heating appliances. Unlike state-of-the-art proposals, this converter achieves a full-output-power operating range of up to 3.6 kW. Consequently, it provides a high-performance cost-effective alternative to current implementations. The proposed converter is analyzed in this paper and experimentally verified using a dual-output 3.6-kW induction heating appliance prototype.

The coupled mode theory (CMT) and parity-time (PT) symmetry were recently used in studying wireless power transfer (WPT) systems. This paper re-examines these approaches. The limitations of CMT and PT symmetry are identified and highlighted so that WPT researchers can avoid their pitfalls. Electric circuit theory (ECT) is based on laws of physics and offers exact solutions. CMT is actually derived from ECT through two simplification stages, and it only gives approximate solutions. CMT involves assumptions that neglect high-frequency components in the WPT systems. Therefore, CMT cannot offer more information and better accuracy than ECT for WPT studies. The PT symmetry leads to the zero-phase-angle condition that was well known from previous WPT research based on ECT for minimizing reactive power flow and maximizing efficiency. The limitations of these two approaches are explained in detail and compared with ECT with practical examples. Both theoretical and practical results are included in the comparison. These results show that CMT and PT symmetry have shortcomings arising from their respective underlying assumptions. They do not offer new explanations and insights that ECT cannot offer. ECT is still the most appropriate analytical tool to study near-field WPT systems on the conditions that the dimensions of the circuit components are much smaller than the wavelengths of the operating frequencies.

The arm impedance in a modular multilevel converter (MMC) influences both the internal dynamics and the converter impedance, significantly impacting the overall system stability. This article proposes a damping method with virtual arm impedance to suppress the small-signal oscillations caused by impedance interactions and improve the MMC stability. The virtual arm impedance, including both a resistance and a reactance component, is emulated based on the common-mode (CM) second-harmonic circulating current, which is injected to optimize the capacitor voltages of MMCs. Different from existing virtual impedance methods, the steady-state operation of the MMC is not influenced by the CM virtual arm impedance. It is shown that the virtual reactance of the same impedance has a better damping effect, compared with the virtual resistance. Selection guidelines of virtual reactance are also provided considering both the stability margin and dynamic performance. Moreover, the stability improvement is quantified by a stability boundary map and validated by real-time grid interaction studies and experimental results. This paper is accompanied by a video file demonstrating the experimental validation of the proposed virtual arm impedance emulation methods.

Switched capacitor (SC) circuits have been widely used for low-power and high-power areas, such as the integration circuit power supply, energy conversion for wearable devices, and power supply for data centers and electrical vehicles. The dc–dc conversion, dc–ac inversion, ac–dc rectification, and ac–ac conversion of SC topologies have been explored and discussed. This article provides a review of different topologies, application areas, mathematical models, and control methods for SC circuits. Compared with other review papers on SC converters, this article deeply and comprehensively surveys the topological structure classification and the equivalent circuits. It explores the application fields and the operation performance of SC circuits. The modeling method is presented as the steady-state modeling method and the transient modeling method. It will help to achieve accurate simulation and prediction and lay the foundation for theory analysis. The different mathematical models’ construction algorithms and the suitable application range are analyzed in this article. The control methods determine the quality of the output voltage and the output power for SC circuits. They are classified as the linear control methods and the nonlinear control methods. The nonlinear control methods will help to achieve high-quality output voltage or current regulation with low ripples and fast dynamical response speed. The comparison of different topologies, application areas, modeling methods, and control methods is provided and discussed. What is more, the simulation accuracy of different modeling strategies and static and dynamical regulation performance of different control algorithms are presented in this article, respectively. The challenges and opportunities for SC circuits are prospected.

A chip-level design of 30 A load current and 93% peak efficiency for active clamping forward (ACF) converter is presented in this paper to improve the system performance and compactness for all load range and different input voltages. The topology of the low side ACF and self-driven synchronous rectification is adapted to low output voltage and large load current applications. A homologous IC controller with proposed technique of adaptive maximum duty cycle, slope compensation, and optional driver logic is designed. The IC controller is turned into different working states to cooperate different states of the system and functions for complete protection of overcurrent protection, over temperature protection, under voltage lockout, and soft shutdown. The controller chip is fabricated in 0.18 μm BCD process. The experiment results show that 30 A full load current with a compact volume of 39 cm3 and complete protection has been realized. The overshoot and undershoot of transient response are less than 200 mV at 5 A–25 A within 120 μs and the peak efficiency of 93.0% is achieved.

An efficient closed-loop voltage tracking control (VTC) for a grid-forming-based converter is required for precise voltage regulation. However, few papers designed a VTC exclusively for modular multilevel converter (MMC) with a full understanding of the MMC's internal dynamic coupling and presented a detailed analysis of the controller. In contrast, traditional voltage–current double loop control or its derivatives are employed without considering the impact of the coupled fluctuating capacitor voltage and with insufficient stability analysis under various operating conditions, especially for the wide range of grid short-circuit ratio. To solve these problems on MMC, this article systematically analyzes the effect of each component of capacitor voltages on the output voltage. In this article, an easy-implemental VTC is proposed which takes the dominant factor of capacitor voltage into the feedforward path (CVF). The proposed CVF-VTC with an appropriate feedforward coefficient shows a high damping effect under varying grid strength with the eigenvalue proof of the established small signal model. Moreover, the PI parameters of the VTC show a low effect on system stability when CVF is applied. Experiment results are performed to verify the proposed method.

Power synchronization control (PSC) tends to destabilize the voltage source converter (VSC) connected to the stiff grid. To address this issue, this paper proposes a novel control scheme named power self-synchronization control (PSSC), which enables VSC to operate under grid conditions with a short circuit ratio from 1 to infinity. Similar to PSC, the proposed method also includes a power synchronization loop, voltage control loop, and current control loop. Yet, PSSC-based VSC(PSSC-VSC) can be self-synchronized to the grid without three-phase grid voltage detection. In PSSC, the output of the current control loop is fed back to calculate the instantaneous power, which is applied in the power synchronization loop. By the eigenvalue analysis, participating factor analysis, and impedance-based analysis, the control parameters of PSSC are well-designed, and the robustness of VSC under different grid conditions is improved. Moreover, PSSC-VSC inherits the characteristics of the grid-forming converters, and the theoretical analysis for the proposed method is validated by experimental tests.

Peak current mode (PCM) control is often used nowadays in boost converters to improve the stability and control bandwidth because of its single pole characteristic. However, the slope of inductor current causes large output voltage deviation and settling time during load-transient. This article proposes a peak passive ripple mode (PPRM) control with ac couple to solve the aforementioned load-transient issue. PPRM control generates a passive ripple for modulation and couples output voltage signal by the passive RC circuit to achieve a fast transient response. Thus, the current sensor and active circuits can be eliminated. Small signal models are proposed for proposed controls. The experiment and simulation results verified the superior load-transient response of the proposed control with the best figure-of-merit among the recent papers. Compare PPRM control with ac couple to PCM control, the output voltage undershoot/overshoot during load step-up/down reduces to only 42% and 38%, respectively. The proposed small signal models also match the experimental results.

Lift-off of aluminum bond wires is one of the main failure mechanisms of insulated gate bipolar transistor (IGBT) modules. Its root cause is the crack propagation, which causes reduction in the contact area of bond wires at the bond-metallization interface. Thus, lifetime prediction based on the classic Paris law is very appealing due to its capability to account for such a failure mechanism. However, Paris law is currently restricted due to its dependency on inaccurate but expensive means to observe the crack rate. In this article, an analytical calculation method for the crack length of bond wires is proposed by the degradation curves of VCE,on measured during normal power cycling tests. The dye-and-pry method has been used to measure crack lengths to further validate the proposed analytical calculation method. The proposed analytical calculation method can avoid time-consuming measurement of crack length, and can economically calibrate the key constants c and m of Paris law, which has been employed to predict the lifetime of bond wires of IGBT modules by finite element method. Finally, the calibrated values of c and m make Paris law have better applicability to predict the lifetime of bond wires comparing c and m values reported in existing papers.

Active clamp flyback (ACF) converter is regarded as a good candidate in high-frequency small-size adapters. With adaptive dead-time optimization method, there is no reverse conduction loss and switching-on loss in power switches, then ACF can realize optimum full-ZVS control at every operating conditions. However, the other losses such as the conduction loss of clamp switch, the primary winding loss of transformer may be increased to counteract this efficiency advantage, but which has not been outlined. Therefore, this paper proposes a higher-efficiency predicted hysteresis current mode control strategy with adaptive dead-time and partial-ZVS regulation for GaN-based ACF converter for the first time. First, the accurate analytical model by considering above losses is derived. Second, the optimal valley current is calculated by the minimum loss, to determine the conduction time of clamp switch and the dead time of main switch. Finally, a digital controlled GaN-based ACF converter is designed to verify the method. The computation speed of needed analytical equations and the magnetizing inductance offset are considered in implementation process. The experimental results show the proposed method can improve efficiency by 0.4% than existing method, which also show a fast dynamic response since the cycle-by-cycle variable-frequency control concept.

This article presents a single stage isolated bidirectional DC–DC converter comprising of LCL-T resonant network for universal electric vehicle (EV) charging. Fixed frequency operation along with phase-shift control enables easier design of passive components, while achieving high efficiency across wide output voltage range. Furthermore, to increase the switching frequency and consequently the power density, gallium nitride (GaN) switches are explored in the proposed solution. In order to facilitate use of commercially available 650 V GaN transistors, a multi-level inverter and a reconfigurable rectifier architecture is utilized along with LCL-T resonant network, accommodating an input voltage of 800 V, generated from an universal three phase ac input supply, and an output voltage ranging from 150 V to 950 V catering to large variation of battery voltages from different vehicle manufacturers. The constant input voltage-to-output current gain property of LCL-T network, along with an efficient phase-shift modulation proposed in this paper enable soft switching of all transistors with minimum circulating currents over constant current (CC), constant power (CP), and constant voltage (CV) modes of battery charging. Experimental results are provided for a single-phase DC–DC converter prototype utilizing 650 V GaN transistors operating from an 800 V DC bus and providing a very wide output voltage from 150 V to 950 V at 6.6 kW maximum power at a constant switching frequency of 500 kHz. The prototype achieves two peak efficiency points of 98.2% and maintains $>$ 97% efficiency across the entire output voltage range at a power density of 120 W/in3 (7.3 kW/L).

Synchronous rectification that is being widely used in high power and current DC-DC LLC resonant converters to reduce conduction losses can be challenging in single-stage AC-DC LLC converters with high output voltage levels (i.e., >200 V) where synchronous rectifier (SR) driving ICs cannot be used. In this paper, a simple AC line cycle synchronous rectification strategy with direct control by a cost-effective microcontroller unit (MCU) is proposed for single-stage AC-DC LLC converters with high switching frequencies using wide bandgap devices (i.e., GaN or SiC). The SR gate pulse is generated based on the time-domain calculated conduction time, which is then switched on and off over the AC line cycle to avoid reverse power flow in light load conditions. The proposed strategy reduces the complexity of implementation over any adaptive online calculation or model-based methods that require powerful and expensive MCUs. First, the operation is briefly described followed by the time-domain analysis for AC operation. Next, the calculation and methodology behind the proposed AC line cycle SR driving strategy are discussed in detail. A scaled-down wide bandgap-based AC-DC LLC converter prototype with a 250--400 V output voltage range is used with digital control implementation to validate the performance of the proposed synchronous rectification strategy. It is found that maximum efficiency of 98.1% can be achieved which is improved by around 0.5% over the conventional fixed conduction time method. Moreover, it is shown that the proposed method obtains the same efficiency levels as more complex adaptive SR driving approaches.

State-of-the-art CubeSat electric power system (EPS) architectures employ multiple dc-dc converters to regulate the load voltage and maximize the solar energy harvest. However, this leads to the use of multiple bulky inductors in the CubeSat EPS which is much constrained by strict volume and weight restrictions. With the aim of achieving smaller EPS footprint, this paper presents a new single-inductor based multiple-input–multiple-output (MIMO) converter for CubeSat EPS. The operational principles of the proposed converter and its steady-state analysis are discussed, and converter modeling is performed. A control strategy is developed to achieve voltage regulation of the CubeSat loads and maximum power point tracking (MPPT) for the photovoltaic (PV) panels under a wide-range of irradiation conditions. An experimental prototype based on the 1 U CubeSat specifications is developed to validate the performance of the proposed MIMO converter.

This article analyzes the dynamic characteristics of a dual active bridge (DAB) converter with input/output LC filters connected and power-feedback control applied, and then discusses an impedance stability criterion about both side LC filters and the converter. Power control is suitable as a control method for grid-connected converters because of its affinity with the energy management system, which is being introduced as a new way to operate power systems in recent years. In order to provide stable power supply, it is necessary to ensure the stability of the converter, and information on dynamic characteristics is essential for the design and development of converters. Since there are no previous papers found yet where the impedance stability criterion is applied when LC filters are connected to both ends of a bidirectional DAB converter, this article discusses the procedures and key points to be considered to apply the criterion. Based on the analysis, the design guidelines of the system will be discussed.

In the traditional optimization model of central air-conditioner, the loss model of converter-fed motor is very rough, resulting in a large amount of energy waste. In this paper, a new energy loss model of central air-conditioning system from power to client is proposed. In the establishment of the loss model, the characteristics of pump load and variable frequency speed regulation are fully considered, and the electromagnetic variables which are difficult to be collected are replaced by the motor speed which can be directly calculated, so that the motor loss model can be introduced into the optimization model of the central air-conditioning system. A 5.5 kW converter-fed induction motor is tested under different speeds and loads, and the two-dimensional (2-D) loss data were obtained. Then, one-dimensional data were extracted from the measured 2-D data combined with the load characteristics of the pump, and compared with the calculated values of the proposed model in this article. The results show that the proposed loss model is of good accuracy and versatility. Because the proposed analytical model only needs the variable of motor speed to accurately estimate the losses, it can be easily applied to the optimization of central air-conditioning system.

In the paper by Barbi (2021), the concept of series loss-free resistor (SLFR) was presented. The SLFR was realized by novel circuitry derived by topological variation of classical noninverting buck–boost converter operated in discontinuous-conduction mode. The purpose of this note is complementing the work of Barbi (2021) by demonstrating that SLFR may also be realized by classical converters employing dedicated current loops. Validation is carried out by realizing the capacitors balancer example by Barbi (2021) by means of a classical noninverting buck–boost converter, demonstrating the results similarity.

Wireless power transfer (WPT) technology has become a developing trend with the advantages of flexibility and security. However, WPT systems also face some challenges, such as output power fluctuations caused by misalignment or dynamic charging, accurate modeling of high-order systems, system integration, load estimation, and simultaneous transmission of power and data. Therefore, advanced topologies and magnetic coupler design for WPT systems are becoming critical topics. This Special Section on Advanced WPT Systems With High Efficiency and Misalignment Tolerance Characteristics in IEEE Transactions on Power Electronics (TPEL) provides an insight into some of the newly emerging challenges and potential solutions to overcome those issues. For this Special Section, 120 submissions were received. Twenty-three are published in the October issue. The rest of the papers will be published in the November and December issues of TPEL.

Presents corrections to the paper, A Novel Filter With High Harmonics Attenuation and Small Dimension for Grid-Connected Inverter.