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Due to its unique features, the flyback converter is widely used to convert DC to DC power. This converter has a non‐minimum phase (NMP) dynamic behavior, which is one of its most significant disadvantages. By changing the topology of the flyback converter to a forward‐flyback (FF) converter, the dynamic behavior of the converter can be minimum phase (MP) while the main advantages of the flyback converter such as isolation of the output from the input and simple topology are maintained. This article proposes an innovative FF converter topology by doubling the forward path and adding only one diode and one capacitor. In addition to better dynamic behavior, the proposed double FF (DFF) converter has the same advantages as the conventional FF converter. A new method is used to obtain the transfer function of the output voltage to the duty cycle of the proposed converter. The converter is designed in continuous conduction mode (CCM) with minimum phase dynamics. Finally, simulation and experimental results of both conventional FF and the proposed DFF converters are obtained and compared to validate the superiority of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper introduces a new structure of a multi-level inverter (MLI) to generate high-level AC voltages using a low number of switches with a quasi-sine waveform. The small number of driver circuits utilised in bidirectional switches is a salient characteristic of this inverter. Also, the number of conducting switches at each voltage level is low in this structure. This results in lower conduction losses of the switches. The proposed topology can be used as the cascaded structure with different approaches to select the value of voltage sources. Power losses are discussed for the proposed structure. To compare the proposed multi-level inverter and demonstrate its superiority, a comparison has been made with some recently presented topologies. According to the comparison results, the advantage of the proposed structure is producing high voltage levels with a smaller number of switches and driver circuits. To prove the suitable performance of the proposed MLI, a 21-level symmetric and 37-level asymmetric inverter containing 14 switches are designed and simulated in the MATLAB/Simulink program. A laboratory prototype for each of these inverters is implemented. The experimental results finely verify the simulations. Besides, an accurate comparison with recently introduced multilevel inverters has been carried out to confirm the effectiveness and superiority of the proposed structure. [ABSTRACT FROM AUTHOR]

Layout stitching is a repetitive and tedious task of the radio frequency integrated circuit (RFIC) design process. While academic research on layout splicing algorithms mainly focuses on analog and digital circuits, there is still a lack of well-developed algorithms for RFICs. An RFIC system usually has a symmetrical layout, such as transmitter and receiver components, low-noise amplifier (LNA), an SPDT switch, etc. This paper aims to address this gap by proposing an automated procedure for the layout of RFICs by relying on the basic device/PCell structure based on the interconnection among circuit topologies. This approach makes the in-series generation of layouts and automatic splicing based on circuit logic possible, resulting in superior stitching performance compared with related modules in Advanced Design System. To demonstrate the physical application possibilities, we implemented our algorithm on an LNA and a switch circuit. [ABSTRACT FROM AUTHOR]

Gallium nitride high electron mobility transistors outperform Silicon devices due to their excellent physical properties. However, being an immature technology, it exhibits dynamic on-state resistance ($R_{\text{ds}, \text{on}}$). This causes increased conduction loss and leads to reduced operating efficiency. To evaluate the dynamic $R_{\text{ds}, \text{on}}$ of the device, a measurement circuit is required. In literature, a standardized double pulse test is widely used for the measurement of $R_{\text{ds}, \text{on}}$. However, due to the uncontrolled off-state time and inability to independently adjust, the test conditions result in restricted measurement. This article proposes a measurement circuit of the device in power electronics operations. The circuit uses an H-Bridge-derived topology with capacitive storage to enable forward and reverse conduction mode measurement of the device. In all the modes, the circuit allows measurement from the first switching cycle and independent control over the testing conditions by using a hysteresis current control. The proposed measurement circuit is validated using simulation and experimentation. Finally, analytical efficiency compared with the state-of-the-art measurement circuits is provided. [ABSTRACT FROM AUTHOR]

This article introduces a new nonisolated soft-switching coupled-inductor (CI) step-up dc/dc converter. The presented topology utilizes a three-winding CI (TWCI) along with a voltage multiplier circuit to increase the voltage conversion ratio without needing a high duty cycle. Using this circuit, a high voltage gain can be achieved without requiring a large number of turns ratio in the CI. The input current ripple of the introduced converter is very low, which is very desirable for renewable energy sources applications. The TWCI also creates an additional design freedom to increase the voltage gain, which indicates more circuit flexibility. Additionally, the voltage stress across the single power switch is limited with the help of a regenerative clamp capacitor. The leakage inductor of the CI is used to create a resonant tank to reduce power losses further. The leakage inductances help provide the zero-current switching conditions for the single power switch and decrease the reverse-recovery issues for all diodes, leading to an efficiency improvement. The operation principle, steady-state analysis, and design considerations are discussed thoroughly. Finally, the theoretical analysis is validated through experimental results obtained from a 200 W prototype with 250 V output voltage. [ABSTRACT FROM AUTHOR]

Existing dc and ac bypass-assisted two-level three-φ inverter topologies can only reduce the peak-to-peak (P-to-P) common mode voltage (CMV) value by 66.6%. However, the dv/dt of CMV remains unchanged. This issue can be easily addressed by using a multilevel inverter but it increases the size, cost, and complexity of the system. As an alternative, this article proposes a novel three-phase inverter topology where one leg (out of three) of the inverter is configured to produce three-level pole voltage while the other two legs produce two-level pole voltages. This results in a unique space vector (SV) diagram with 12 SVs, whereas a 2-level inverter has only 8 SVs. A new pulsewidth modulation scheme is proposed that can utilize the SV diagram in such a way that dv/dt of CMV is reduced by 50% along with a 66.6% reduction in CMV P-to-P value in each switching cycle. Another advantage of the proposed topology is the reduced conduction losses due to fewer switches conducting at any given time. The proposed topology is compared with the existing solutions to prove its advantages. Simulation and experimental results are presented for a three-phase induction motor load to validate the various claims. [ABSTRACT FROM AUTHOR]

Most modern world appliances have an intermediate AC to DC rectifier, whether used for DC (LEDs, chargers) or applications with internal motors (refrigerator, washing machine). The conventional rectifiers distort the power factor and introduce harmonics in the grid. Multilevel rectifiers (MLR) with power factor correction (PFC) and high load handling capability have gained much research focus, and numerous topologies have been reported. However, most of them either fail to maintain the unity power factor (UPF) across the entire power range or to maintain UPF employ external circuitry and control. Further, capacitor voltage balancing is another major issue in MLR. In this regard, this brief proposes a sensor less self-balanced MLR topology that maintains UPF in all operating conditions. Experimental results have been presented for validation of the claims mentioned above of the implemented topology. A quantitative comparison with the recent literature has also been included. [ABSTRACT FROM AUTHOR]

In this article, an improved soft-switching quadratic boost converter is proposed. Instead of inserting an additional active clamp or auxiliary zero-voltage transition circuit at the switching node, the proposed topology connects the high-voltage switching node to the input diode node by replacing one of the input diodes with a low-rated switch. The proposed topology can attain soft-switching condition for all the switches and input diode turns-off under zero-current switching (ZCS). The operation of input-side switch not only aids zero-voltage switching (ZVS) turn-on for the main switch but also helps in reducing the conduction loss. Also, the input-side switch operates under ZCS turn-on and ZVS turn-off, making it a loss economical solution. An adaptive timing scheme for driving the input switch is proposed, which can ensure soft-switching condition under varying gain and load range. The detailed operational modes, analysis, and design considerations of the proposed topology are presented. A 250 W hardware prototype is built to validate the performance of the proposed converter operating at 100 kHz switching frequency. Results with adaptive soft-switching scheme shows that the converter is modulated to achieve its best efficiency condition under various system conditions. A peak efficiency of 96.1% at 155 W and efficiencies above 95.75% over a wide load range are achieved using all Si devices. [ABSTRACT FROM AUTHOR]

The modular multilevel converter based solid state transformer (MMC-SST) is characterized by a large number of switches and large-size submodule (SM) capacitors, complex system control schemes. In this article, a novel high-frequency link (HFL) interconnection scheme based on MMC-SST (MHFL-SST) is proposed. All the SM capacitors are connected to the common bus (CB) through the full bridges triggered by the same driver signals, operating as a switched-capacitor conversion. The low frequency currents of SMs are decoupled on the CB; thus, the SM capacitance value can be reduced significantly and the circulating currents are also suppressed substantially. Furthermore, the voltages of all SM capacitors are always clamped with each other to be the same due to the switched-capacitor circuits. The bidirectional power conversion of the low voltage dc bus is implemented by phase shift control between a multiplexed H-bridge cell and the CB. The parameter constraint of the switched-capacitor loop circuit and the closed-loop control scheme for MHFL-SST are also carried out. The correctness and effectiveness of the proposed scheme are verified by simulations and experiments. [ABSTRACT FROM AUTHOR]

This letter proposes a switched capacitor (SC)-based continuously adjustable modular bidirectional dc–dc converter. The structure of the proposed converter consists of three types of modules, series–parallel SC converter module, regulating module, and resonant SC converters module. A basic configuration of three modules working in buck operating mode is analyzed in detail. The boost mode operation is symmetrical to the buck mode. The regulation module provides all regulation capability, and the other two modules operate at fixed duty cycle and provide the main conversion ratio. A prototype of the basic configuration was built to verify the theory. The peak efficiency of the prototype is 97.15%. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this article, we introduce a model predictive control with optimal switching sequence (OSS-MPC) for a multilevel static synchronous compensator (STATCOM). The studied STATCOM is based on a hybrid multilevel inverter named HC-FNPC formed by the cascaded connection of H-bridge cells with a full-bridge neutral point clamped cell (FNPC). In this article, the optimal switching sequences are derived for HC-FNPC STATCOM by considering the impact of each switching sequence on the voltage of capacitors. Then, the control objectives of hybrid multilevel STATCOM, i.e., ac current control and capacitors’ voltages balancing, are formulated in terms of OSS-MPC for the first time. In contrast to the conventional MPC, this method provides a fixed-switching frequency. Also, by a combination of optimal switching sequences in MPC, the regulation of capacitors’ voltages with unequal values is realized. The control system's performance is verified on a nine-level (9L) 2.4 Mvar/11 kV HC-FNPC STATCOM in MATLAB/Simulink. Also, the experimental results are provided on a 9L 1.25 kvar/220 V scaled-down hardware prototype. [ABSTRACT FROM AUTHOR]

Piezoelectric energy harvester (PEH) arrays are practical solutions to the low and unreliable power output of a single PEH. However, most PEH circuits are developed for addressing the one-channel ac input from a single PEH. In this article, an extensible rectifier-less synchronized switch harvesting on inductor (ReL-SSHI) array interface with the maximal power point tracking (MPPT) function to manage the multiple ac inputs from the PEH arrays is designed. The ac–dc conversion is performed by the ReL-SSHI topology with passive peak switches featured with self-powered characteristic and fast cold-start. Only one shared inductor is employed, greatly reducing the circuit volume and cost. The MPPT module for each channel is implemented by a simple envelope detector and an ultra-low power hysteresis controller and achieves continuous energy extraction by adapting the fractional normal-operation voltage method. A developed discrete array interface able to handle three PEHs effectively executes the MPPT for each channel with the uphill and downhill response speeds of 2.0 and 7.1 V/s, and a maximal MPPT efficiency of 97.1%. This circuit boosts the power output by 485% compared with that by the traditional full-bridge rectifier, around 33% higher than that from existing synchronous electric charge extraction array interfaces. [ABSTRACT FROM AUTHOR]

This study introduces a new modified high-gain single-switch single-ended primary-inductor converter-based dc/dc converter. The low input ripple of the proposed converter makes it very suitable for renewable energy applications. In the proposed topology, a three-winding coupled-inductor and a voltage doubler rectifier are used to achieve high voltage gain without needing an extreme duty cycle. This circuit can provide an ultra-high voltage conversion ratio without requiring a large number of the turns ratio of the three-winding coupled-inductor (TWCI). Due to a regenerative clamped circuit, the leakage energy of the coupled-inductor is recycled; thus, the maximum voltage spike across the single-power switch is restricted. Therefore, mosfet with a low maximum voltage rating can be utilized, which can alleviate the conduction power dissipations of the converter. Here, the switching power losses have been reduced significantly due to the circuit's soft-switching operation for the switch and all diodes. The steady-state analysis of the proposed converter is discussed thoroughly. Finally, the theoretical analysis is verified through the experimental results from a sample prototype (400-W, 25-400 V). [ABSTRACT FROM AUTHOR]

A single-stage high power factor (HPF) improved power quality charging solution for light electric vehicles (LEVs) is presented in this work. The charger topology comprises a bridgeless isolated modified SEPIC (BIMSEPIC) HPF ac–dc converter, to accomplish various charging modes with high performance at the supply side. Unlike conventional bridgeless SEPIC topologies, the presented topology ensures zero circulating current through the antiparallel diode of the switch, utilizes a single switch structure, and requires simple gate drive circuitry. Further, the discontinuous conduction mode operation of the charger significantly simplifies the control complexities and associated cost of implementation. Additionally, the magnetic component's volume and switching losses are reduced considerably. Finally, the presented topology is designed, simulated, and implemented to verify its efficacy for the LEVs charging applications. A comprehensive analysis is carried out at various operating conditions, and the relevant test results are demonstrated for the performance verification. Moreover, a comparative analysis with existing chargers verifies the excellent performance of the presented charger topology. [ABSTRACT FROM AUTHOR]

This article presents a self-configurable and self-poweredactive rectifier that operates from 0.25–20 V for energy harvesting applications. The proposed circuit self-startups from a low voltage using a charge pump and amplifies the voltage with a voltage doubler topology to provide succeeding circuits such as boost converters with a higher voltage. When the voltage of the energy harvester reaches a high threshold, the circuit switches its topology to a full-wave rectifier that does not amplify the voltage. The start-up circuit can limit its voltage intake to prevent boosting the high voltage, which may damage the whole circuit. Comparators with a maximum operating voltage of 5.5 V used in the implementation of the rectifier are protected by a diode and resistor based circuit. A piezoelectric energy harvester (PEH) that has a wide open-circuit voltage of 0.4–15 V under the acceleration of 0.04–0.3 g was used to test the circuit. The experiment results showed the rectifier can startup from 0.25 V and switch its topology according to the PEH voltage. The voltage and power conversion efficiencies are over 90% in most cases. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLIs) with switched-capacitor (SC) units have been a widely rehearsed research topic in power electronics since the last decade. Inductorless/transformerless operation with voltage-boosting feature and inherent capacitor self-voltage balancing performance with a reduced electromagnetic interference make the SC-MLI an attractive converter over the other available counterparts for various applications. There have been many developed SC-MLI structures recently put forward, where different basic switching techniques are used to generate multiple (discrete) output voltage levels. In general, the priority of the topological development is motivated by the number of output voltage levels, overall voltage gain, and full dc-link voltage utilization, while reducing the component counts and stress on devices for better efficiency and power density. To facilitate the direction of future research in SC-MLIs, this article presents a comprehensive review, critical analysis, and categorization of the existing topologies. Common fundamental units are generalized and summarized with their merits and demerits. Ultimately, major challenges and research directions are outlined leading to the future technology roadmap for more practical applications. [ABSTRACT FROM AUTHOR]

Active magnetic bearing (AMB) technology has been widely used in high-speed electrical machines. Power electronics controller amplifier is an important segment in AMB system. Failure of power electronics device is a common threat to the reliability of AMB amplifier and can cause serious damage. In order to improve the robustness of the amplifier, this article proposes open-circuit fault-tolerant control strategies based on different topologies. For single-axis systems, a pair of windings with a single degree of freedom can work in four different working modes based on the three-phase full-bridge structure. It can detect and locate the open-circuit fault of a power electronics switch in operation. After promotion to multiaxis systems, a novel kind of topology for amplifier with fault tolerant strategy has been proposed that can also detect the open-circuit fault of power electronics switch and switch to fault tolerance mode for a multiaxis system. Fault tolerant experiments verify the feasibility and rapid response of different fault tolerance strategies with an AMB testbed in this article. [ABSTRACT FROM AUTHOR]

To balance dc voltage, a two-module structure based on a dc–dc three-level boost converter is utilized. In this article, the possible operating modes for a two-module converter in the steady state are introduced. These modes are performed according to different states of opening or closing of the switches. Total 16 possible operating modes and the operation of different switches in the circuit are shown. The circuits for each operating mode are drawn according to the switch command signals. The relationships governing the system are given in different modes. These equations include the currents through three output capacitors and the inductor voltages of each module. The system is simulated by MATLAB/Simulink. The waveforms of the system are presented in two cases for different operating points. The operating mode of this structure is validated using simulations and experimental results. [ABSTRACT FROM AUTHOR]

This article proposes a single-phase five-level current source inverter with an inductor cell based on the switching-cell (SC) structure. Compared to the conventional inverter, the proposed structure has no open-circuit problem; thus, its reliability is greatly enhanced. The overlap-time inserted in the driving signals can also be minimized to improve the output waveform quality. The proposed inverter's operation is analyzed herein, and the design guideline of SC capacitors is discussed. In addition, the SC extension for the n-level topology is provided. A 1-kW prototype is built and tested to validate the effectiveness of the proposed structure. [ABSTRACT FROM AUTHOR]

The development of a low-voltage dc distribution network has advanced the research on dc circuit breakers. Compared with the Z-source circuit breakers, T-source circuit breakers offer more advantages and greater research value. However, the existing bidirectional Z-source and T-source circuit breakers still suffer from limitations, such as high conduction loss, complex topology, and no physical isolation. Therefore, to solve these limitations, in this article, a novel low-loss bidirectional T-source circuit breaker with physical isolation is proposed. The proposed circuit breaker employs mechanical switches to reduce conduction loss, realize physical isolation, and change the power-flow direction. Since mechanical switches do not need to operate in the fault-clearing stage, the novel circuit breaker does not generate a dc arc and retains the fast self-shut-off characteristic of T-source circuit breakers. Moreover, soft-starting circuit and manual-tripping circuit are integrated into the proposed circuit breaker. The detailed analysis and design equations of the circuit breaker are provided. Finally, the capabilities of the novel circuit breaker are verified by simulation and experiment. [ABSTRACT FROM AUTHOR]

A high voltage gain single switch DC-DC converter with efficient leakage energy recovery is presented in this brief. Effective leakage energy recycling is an important requirement in this class of converters with coupled inductors to overcome the high voltage stress across semiconductor devices. The proposed converter effectively recycles the leakage energy of the coupled inductor through a passive clamp circuit to the load. Hence, the efficiency of the converter is improved considerably. The proposed converter has the lowest switch voltage stress among other similar topologies, thereby making it feasible to select a low rating switch for the same boost gain. The converter has a lower sum of diode voltage stress and improved reverse recovery performance of the output side diode as well. The converter performance has been evaluated on the basis of different factors like efficiency, switch voltage stress, diode voltage stress, etc. The proposed converter performance is compared with that for various competitive topologies and is observed to be performing better. The effect of leakage inductance variation is studied on the gain of the converter. The proposed concept is verified via simulation and experimental prototype. [ABSTRACT FROM AUTHOR]

Two 17-level inverters based on switched capacitor (SC) are presented in this article. Each of them involves two SC units and a neutral-point-piloted unit. A total of four pairs of transistors, a bidirectional switch, two pairs of diodes, and three pairs of capacitors are employed. All of the switching components are controlled by six pulsewidth modulation signals and all capacitors’ voltages are self-balanced. With an improved selective harmonic eliminated modulation strategy, low-order harmonics are effectively suppressed and switches operate in low switching frequency. In addition to the use of fewer components, high-quality output voltage shape is benefited from the unique topology and reduced capacitor voltage ripple accumulation. Experiment results demonstrate the excellent performance of the proposed inverter. High efficiency is also achieved and the maximum value is up to 98.05%. [ABSTRACT FROM AUTHOR]

Accurate estimation of mutual inductance in wireless power transfer (WPT) system is a prerequisite for accurate identification of load parameters, which is critical in system constant output and efficiency tracking control. In this article, a general load decoupling method for WPT system considering soft-start process and battery initial voltage is proposed. Moreover, a double-sided LCC topology is used to explain how to calculate the boundary conditions of load decoupling. Based on the proposed load decoupling method, a mutual inductance identification method is proposed for WPT system with double-sided LCC topology. Within the frequency range recommended, the unique solution of mutual inductance can be obtained by solving high-ordered equivalent impedance equation. In this case, there is no need to discuss the situation for multiple solutions. Based on the WPT prototype, the effectiveness of the proposed load decoupling method is verified, and parameter sensitivity of the identification method is analyzed in detail. Finally, the proposed method is experimentally verified. Results show that high identification accuracy can be achieved even when the coils are misaligned. Compared with the existing identification methods, the proposed method does not need any additional switches and auxiliary circuits, which reduces the complexity and system cost effectively. [ABSTRACT FROM AUTHOR]

This letter presents a new auxiliary circuit to achieve transient current commutation (TCC) in dc solid-state circuit breakers (SSCBs). The auxiliary circuit consists of two parts: active injection circuits (AIC) and capacitive couplers. There are two contributions. First, coupling capacitors between AIC and the main branch are introduced to prevent short circuit failures in the auxiliary branch. Second, a boost converter-based resonant circuit is presented for AIC to achieve TCC in the main branch through couplers. The presented AIC tunes the duration time and amplitude of injected countercurrent pulses during dc current interruption. The working principle and design procedure of the auxiliary circuit are presented. The proposed topology is verified by experiments of a 2 kV/100 A dc SSCB prototype under load current interruption. The experimental results show that the injected pulse current through couplers reaches 110 A, and it decays to zero within 12.5 μs. The total reaction time interval including the communication delay and the AIC current rising delay is 108 μs. Meanwhile, the peak voltages across the main branch and the coupler reach 2099 V and 2193 V, respectively. [ABSTRACT FROM AUTHOR]

This article presents a new hybrid three-phase cascaded modular multilevel inverter developed with a reduced switch count concept for harvesting renewable energy. The basic module of the proposed inverter consists of six switches, three asymmetric dc links, and two blocking diodes. The inverter can generate six positive voltage states, which are negatively polarized by the end-side H-bridge unit. As a result, a higher number of voltage levels are obtained with a minimum number of switches that ensure reduced total harmonic distortion in the grid current. Additionally, the proposed inverter can operate at a comparatively lower switching frequency, which decreases the switching losses. Most of the switches in each individual module conduct for a small period resulting in low conduction losses. The reduced switch count with the low switching and conduction losses increases the compactness and the efficiency of the proposed inverter. Multiple high-frequency magnetic links are utilized for the dc sources required for the proposed inverter to achieve inherent dc-link voltage balancing ability and galvanic isolation. The performance of the proposed inverter is validated by simulation and experimental investigations. [ABSTRACT FROM AUTHOR]

Multilevel inverters (MLI) are gaining wider popularity owing to their increasing power handling capability and improving power quality output. With an inclining trend towards renewable energy utilization, they find a vital application in wind and solar power generation systems. This article proposes a new multilevel dc–ac inverter. The proposed MLI produces a twenty five level output and offers an inherent capacitor self-balancing capability. The inherent self-balancing eliminates the requirement of auxiliary sensor circuit or capacitors voltage balancing algorithms. Dual asymmetric voltage sources and switched capacitors along with their proper charging/discharging pattern are utilized for the generation of output levels. A voltage gain of 2 and a total standing voltage (TSV) of 10 is achieved though the proposed inverter. In order to realize the merit of the proposed MLI over recently developed topologies, a comparative analysis in terms of system components such as numbers of power electronic switches, gate driver circuits, diodes, and capacitors as well as system parameters such as voltage gain, TSV and power loss is presented. The proposed MLI is developed in the laboratory and is controlled through the digital signal processor TMS320F28379D using nearest level control technique. The experimental results are acquired for different loads and under varying modulation index to validate the feasibility of the proposed inverter. [ABSTRACT FROM AUTHOR]

Multilevel circuits can achieve high-voltage level, power density, and performance. This article considers a dual active bridge (DAB) based on the active neutral-point-clamped (ANPC) three-level circuit (ANPC–DAB). The soft-switching characteristics of the ANPC circuit during the switching process between switching states are analyzed, and the conditions for enabling all 12 switching devices to achieve zero-voltage switching (ZVS) on all the turn-on switching transitions are obtained. Based on this, the distribution of hard-switching turn-off and conduction losses of power devices is further analyzed, and an optimized switching strategy that can balance the loss distribution of power devices is proposed by the evaluation of all zero states and analysis of a switching-state sequence. Moreover, this article examines the effect of the proposed switching strategy by analyzing the loss distribution of power devices and efficiency of the ANPC–DAB. Finally, experiments are conducted using a 1-kW prototype. The simulation and experimental results show that the proposed switching strategy can effectively improve the loss distribution of power devices while all the power devices realize ZVS. [ABSTRACT FROM AUTHOR]

Copyright of Electric Machines & Control / Dianji Yu Kongzhi Xuebao is the property of Electric Machines & Control and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this brief, a new switched capacitor-based structure is presented for a single-phase multilevel inverter. The proposed structure is capable of boosting the input voltage and producing fifteen voltage levels at the output utilizing two separated DC voltage sources along with a switched capacitor unit. The proposed structure also has self-charging capability and can automatically adjust the capacitor voltage without any sensor. A quantitative comparison with similar structures has been performed to confirm the proposed structure. Furthermore, loss and thermal simulations have been performed for the proposed structure. The functionality of the proposed structure is examined by the simulation results. Finally, a laboratory prototype is implemented to verify the effectiveness and accuracy of the proposed structure and its control method. [ABSTRACT FROM AUTHOR]

This letter describes two improved 13-level inverters based on switched-capacitor. Compared with their original structure, which is published recently, one less high-voltage capacitor is required in the proposed inverters and the blocking voltage of their inverting half-bridge is reduced by half. In addition, the new inverters inherit various advantages of the original structure, such as a high boost factor of 6, self-balanced capacitor voltages, and reduced voltage ripples. Circuit description, operation principle, hybrid PWM modulation, and capacitor voltage ripples are analyzed and the feasibility of the proposed inverters is finally verified by experimental results. [ABSTRACT FROM AUTHOR]

This paper presents an optimization framework for sequential reconfiguration using an assortment of switching devices and repair process in distribution system restoration. Compared to existing studies, this paper considers types, capabilities and operational limits of different switching devices, making it applicable in practice. We develop a novel multi-phase method to find the optimal sequential operation of various switching devices and repair faulted areas. We consider circuit breakers, reclosers, sectionalizers, load breaker switches, and fuses. The switching operation problem is decomposed into two mixed-integer linear programming (MILP) subproblems. The first subproblem determines the optimal network topology and estimates the number of steps to reach that topology, while the second subproblem generates a sequence of switching operations to coordinate the switches. For repairing the faults, we design an MILP model that dispatches repair crews to clear faults and replace melted fuses. After clearing a fault, we update the topology of the network by generating a new sequence of switching operations, and the process continues until all faults are cleared. To improve the computational efficiency, a network reduction algorithm is developed to group line sections, such that only switchable sections are present in the reduced network. The proposed method is validated on the IEEE 123-bus and 8500-bus systems. [ABSTRACT FROM AUTHOR]

SRM is one of the most attractive electric machines to be used as a S/G in the future MEA thanks to its special physical characteristics that facilitate its direct coupling to the propulsive unit; however, the controllability of the SRG at different operational points, imposed by the specific application, is critical. In this article, a novel active power control scheme which uses a vector-controlled SAF is proposed, in order to efficiently drive the SRG in a wide set point range. Considering the highly non-linearity of the SRM operational behavior, an adaptive phases’ magnetization regulation is applied, aiming at taking full advantage of the SRG's energy production capability, in compliance with the MEA power system specifications and limitations. The mathematical analysis is verified through simulation results, while the SRG concept under study is validated via a RT CHIL implementation. [ABSTRACT FROM AUTHOR]

The emerging switched-capacitor-based multilevel inverters offer interesting merits such as self-balancing of capacitor voltages and boosting of voltage gain. While the switched capacitors (SCs) in these topologies are charged in parallel with the dc source, severe current spikes issue is inevitable, rendering them impractical at high power. This article proposes a novel switched-capacitor-based T-type inverter that mitigates the current spikes by enabling soft charging for its integrated SCs, where both SC in the topological structure charges through a dedicated circuit comprises of an inductor and two switches. The proposed topology is capable of five-level ac voltage generation and when compared to a classical T-type/ANPC (active neutral-point-clamped) inverter, it achieves higher dc-link voltage utilization since its maximum attainable voltage gain is doubled. Theoretical findings of the proposed topology are validated by both the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Multi‐level inverters (MLIs) for medium or high power and voltage utilization have acceptable application in industry and are utilized commercially. The performance of MLIs is considerably preferable to traditional two‐level inverters due to their negligible harmonic content, small filter size, utilization of lower‐rated voltage devices, low electromagnetic interference (EMI), and so on. However, in the face of these many advantages, few disadvantages can be expressed such as more device count and a sophisticated control strategy. This paper presents an improved switched‐ladder topology to enhance the performance of multi‐level inverters by improving the above drawbacks. Compared to existing inverter topologies, the proposed extendable diode‐containing bidirectional structure requires fewer switches and driver circuits. The proposed topology is compared with other similar topologies, and its superiority is examined. Fundamental switching frequency modulation technique is utilized to obtain high‐quality output voltage waveforms with lower harmonic contents and reduced switching losses. This converter, despite the use of diodes, can supply the low power factor inductive‐resistive loads, bidirectionally. To demonstrate the performance of the proposed topology, in addition to simulation with the nearest level modulation technique, a prototype of the proposed structure has been implemented and tested. The results display the proper performance of the proposed topology in the real‐time environment. [ABSTRACT FROM AUTHOR]

The topology of low-voltage distribution systems changes with the load or the on/off position of the circuit switch. This will affect power flows, losses, and so on. This paper submits a new method to identify the topology of a low-voltage feeder using the injection high-frequency signal. An inductor can block the high-frequency signal. It can change the propagation direction of the injected high-frequency signal to make it propagate unidirectionally along the low-voltage feeder. By injecting a 5 MHz sinusoidal signal from the upstream direction of the low-voltage feeder, all the line segments and devices on the feeder can be identified. The wavelength of the high-frequency signal is short. The wavelength of the 5 MHz signal is 60 meters. Through the delay of different observation points on the feeder, the length of the line section can be roughly calculated. The highfrequency signal has an obvious reflection on the feeder. Using this feature, we can roughly calculate the length of the line segment. The correctness of the method is demonstrated by MATLAB simulation verification. [ABSTRACT FROM AUTHOR]

Given the recently available IGBT switch modules up to 6.5 kV, 1200 A rating, the prospect of the diode-free variant topology of the three-level neutral-point-clamped (3-level T-type, NPC) inverter in certain medium-voltage applications is bright due to its small part count and low conduction losses compared to the diode-clamped NPC inverter. However, within this voltage range, the input dc voltage rating of 50% of the switches per inverter phase-leg still poses limitations to the deployment of a 3-level T-type inverter. In view of these limitations, a reconfigured four-switch per phase-leg power circuit for a 3-level inverter (F-type) is presented in this article. The common node of the bidirectional switch in the T-type inverter is explored to have only one power switch rated at input dc voltage and three switches rated at half the input dc voltage per inverter leg. This reduced voltage stress has inverter cost and loss implications. The performances and competitiveness of the three-level F-type inverter are analyzed in detail and demonstrated with a hardware prototype. Results reveal that it has the potentials of being considered a real alternative to 3-level T-type inverters for certain low- and medium-voltage applications. [ABSTRACT FROM AUTHOR]

Due to the continuously increasing demand on switched-mode power converters (i.e., dc–dc, dc–ac, ac–dc, and ac–ac) that can achieve high efficiency at high switching frequency, soft-switching techniques have received much attention in the area of power converter applications over recent years. This article provides a comprehensive review of the state-of-the-art soft-switching techniques used to achieve the zero-voltage switching and zero-current switching supplied by power switching devices. First, the auxiliary-circuit-based and nonauxiliary-circuit-based techniques that perform soft switching are systematically classified according to power converter. Next, soft-switching techniques for each power converter are comprehensively classified and reviewed in detail. Unlike the existing review papers that only categorize the soft-switching techniques used in dc choppers and inverters, this article offers further helpful categorization for all types of power converters. Further, it provides the merits, demerits, and suitable applications for each soft-switching technique. Finally, it suggests future research issues for soft-switching techniques in power converters. [ABSTRACT FROM AUTHOR]

Switched-capacitor-based multilevel inverters have been gaining increasing attention in recent years in view of their voltage-boosting capability and capacitor self-balancing properties. However, the existing topologies, which comprise frontend switched-capacitor cells and a backend H-bridge, result in longer discharging duration in some of their switched-capacitors. In addition, the adoption of backend H-bridge introduces common-mode voltage and necessitates multiple dc sources for voltage level extension. To resolve these problems, this article proposes a novel topology comprises a T-type inverter and n cascaded switched-capacitor cells. It requires only a single dc source and it manages to mitigate the common-mode voltage by connecting the neutral of ac output to the mid-point of dc link. All switched-capacitors in the proposed topology are ensured to be charged for at least half of the fundamental period to alleviate the capacitor voltage ripples and current spikes. The operation of the proposed topology is analyzed and experimental results are presented for validation. [ABSTRACT FROM AUTHOR]

This article presents a three-port dc/dc converter along with a new control system to integrate solar panels and energy storage in a dc nanogrid. The proposed control system utilizes the duty cycle as well as the switching frequency to control the power flow between the three ports. The proposed converter offers a low number of components, low cost, and high reliability. Moreover, it is capable of providing bidirectional power flow for the energy storage system and the dc grid while having soft-switching for power semiconductors. The converter demonstrates high design flexibility in accommodating different applications. Theoretical analysis and experimental results verify the feasibility and demonstrate the superior performance of the proposed converter. [ABSTRACT FROM AUTHOR]

Multilevel inverter concepts (MLIs) with switched capacitor (SC) are emerging due to their scope in sustainable energy systems as well as high-voltage applications. In the SC technique, required voltage levels can be achieved with the lesser number of dc sources in combination with the capacitor voltage. In this perspective, the design of high-gain MLI with reduced sources as well as switch count is a challenging task. This letter proposes a single-source-driven quadruple boost multilevel inverter topology (QB-MLI) with lesser order of resources over the other SC MLIs. The proposed QB-MLI is capable to produce nine levels of voltage in output by effectively balancing the two capacitor's voltage with the associated control logic. The different SC MLIs are compared to verify the pros and cons with respect to the contribution of the proposed QB-MLI topology. Detailed experimental results at various test conditions of a laboratory set-up have been presented to validate the performance of the proposed QB-MLI. [ABSTRACT FROM AUTHOR]

The resilient consensus of multi-agent systems with trusted agents under switching topologies is addressed in this brief. A novel assumption on switching topologies is proposed, which is different from the existing works dependent on the classical graph robustness condition. Correspondingly, the trusted-region-based sliding-window weighted (TSW) algorithm is proposed to filter the received sampled data. It is successfully shown that the resilient consensus can be guaranteed under the assumption on switching topologies and TSW algorithm. Finally, numerical examples are conducted to validate the results. [ABSTRACT FROM AUTHOR]

This article introduces a cascaded packed U cell (CPUC) multilevel converter (MLC) to achieve a higher-level count in converter voltage with a minimum number of switches. Here, two five-level packed U cell topologies are connected in a cascaded manner to obtain 25 levels in its output converter voltage. The switch count in CPUC is reduced to 12, as compared to the number of semiconductor devices used for obtaining 25 levels in converter output. A binary-quintuple progression is used for selection of voltage ratios between dc voltage sources and capacitors. CPUC is operated at low-frequency switching, using the nearest level modulation technique. The fundamental switching frequency ensures reduced switching losses as compared to pulsewidth modulation schemes. The converter performance is analyzed for grid-tied and standalone applications. The performance parameters such as total harmonic distortion (THD) of converter voltage and THD of grid/load current are examined. The CPUC configuration is modeled and simulated in MATLAB/Simulink, and test results are taken using OPAL-RT test bench. The acquired simulation and test results confirm viability, practicability, acceptability, and cost-effectiveness of CPUC-MLI converter over existing MLC topologies for efficient power conversion. [ABSTRACT FROM AUTHOR]

In this article, the arm phase-shift conducting modulation (PSCM) is proposed for the alternate arm multilevel converter (AAMC). With the PSCM strategy, the half-bridge (HB) structure could be applied as the submodule (SM) topology to reduce the circuit complexity of the full-bridge submodule based AAMC. First, the phase-shift angle is introduced to match the voltage modulation ratio and power factor of ac grid. The energy stored in the submodule capacitors are balanced by regulating the phase-shift angle. Then, the design criteria and operation performance for HBSM-AAMC with the proposed PSCM strategy are analyzed and presented. Compared with HBSM-modular multilevel converters (MMC), 18% HBSMs and 9% power devices are reduced with the proposed topology and modulation, resulting in the lower construction cost. Furthermore, the loss distribution is analyzed, and the operating losses of HBSM-AAMC are smaller than that of HBSM-MMC. Finally, the simulation and experiment are performed to verify the effectiveness of the derived topology and the proposed modulation strategy. [ABSTRACT FROM AUTHOR]

This study focuses on a zero voltage transition multi‐input quasi‐Z‐source converter (qZSC). This topology can be used for input sources with different voltages and currents to provide a constant output voltage. In the proposed structure, several qZSCs are combined and the output filter of all stages is eliminated. Therefore, the overall number of circuit elements, cost, volume and weight are reduced in comparison with when they are in a separate operation. In this converter, the soft‐switching conditions are provided for all stages by using only one auxiliary circuit. The employed technique provides zero‐voltage zero‐current switching (ZVZCS) and zero‐voltage switching for main switches at turn‐on and turn‐off instants, respectively. The auxiliary switch turns on under zero‐current switching and turns off under ZVZCS. Furthermore, the reverse recovery losses of diodes are reduced. The theoretical foundation of the proposed converter is presented and its performance is simulated by OrCAD software. The obtained results show 3.5% improvement in the efficiency at nominal loads, compared to its hard‐switching counterpart. A dual‐input prototype of the proposed structure is successfully built to support the validity of the theoretical analysis. [ABSTRACT FROM AUTHOR]

Boost type switched-capacitor inverter topologies are highly suitable for photovoltaic based distributed power generation and electric vehicle applications. This brief proposes a new single-stage boost type inverter topology with features of self-voltage balancing capability of floating capacitors (FCs), seven-level (7L) stepped output voltage generation with peak output voltage three times higher than the input voltage. The modes of operation are discussed in detail emphasizing the self-voltage balancing. Further, the proposed topology uses less number of semiconductor devices. A detailed comparison with other recent 7L inverter topologies is presented to attest to the merits of the proposed topology concerning a reduced number of components. Finally, a laboratory prototype is employed to validate the proposed topology’s operability, and the obtained experimental results are presented. [ABSTRACT FROM AUTHOR]

A new boosting multilevel inverter with switched-capacitors is presented in this brief. By employing 13 switches, two diodes, and three capacitors, a 13-level voltage waveform is synthesized. The capacitor voltages are self-balanced as they are connected in parallel with the input voltage source for several instances in every fundamental cycle. A simple logic gate based pulse-width modulation scheme ensuring power balance among the capacitors is presented. Experimental results obtained from a laboratory prototype are presented for validating the operation and ability of the proposed inverter to boost the input by a factor of six. Finally, a detailed comparison with existing topologies proves the cost-effectiveness, a simpler structure requiring lesser space and footprint area of the proposed topology. [ABSTRACT FROM AUTHOR]

The modular multilevel converter (MMC) has been proven to be an effective solution for grid-tied applications with medium/high voltage ratings. The MMC contains a large amount of floating capacitors, which require the voltage balancing control. The voltage balancing control complexity is normally increased with the number of floating capacitors. As a result, the computation burden of the controller as well as the corresponding hardware cost will be high. This article proposed a novel Z-type MMC, which can achieve capacitor voltage self-balancing without any balancing control. Therefore, the overall control of the converter is significantly simplified. Both mathematical analysis and experimental results have confirmed the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The noninverting buck–boost (NIBB) converter is a step-up and step-down dc–dc converter suitable for applications with a wide input voltage range. However, this circuit will face the problem of operating mode switching when the input voltage is close to the output voltage. Considering this problem, the principles of the NIBB converter are analyzed in this article. The duty cycle combinations of an NIBB converter are analyzed, and an analysis method for the mode transition problem from a geometric perspective is proposed. Using the two-edge pulsewidth modulation method, a novel bumpless mode transition control method is proposed. A nonlinear feedforward controller with hysteresis is designed according to the state equation of the circuit. Moreover, the inductor current reference value is compensated when the mode is switched so that the mode transition problem of the NIBB circuit is effectively solved. In addition, a small-signal analysis of the proposed method is performed. The analysis shows that the proposed method has good stability and dynamic performance in various typical conditions. A 10-kW NIBB prototype is built in this article, and the corresponding experimental scenarios are designed. The experimental results show that compared with the results of unified PI control during the mode transition, the transient oscillation of the output voltage is smaller, and the duration of the transient process is shorter. [ABSTRACT FROM AUTHOR]