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This paper introduces a new zero current switching topology for parallel balancing of serially connected batteries string. The main advantage of the balancing concept in this study is that energy is transferred only when the cells are unbalanced. As a result, the power losses are significantly reduced since no current circulates through the system when balanced. This has been enabled by a modification of an isolated series-resonant converter operating in a discontinuous conduction mode. A single transformer for two cells is used, as opposed to conventional isolated topologies that require a transformer per cell. The realization is simple and sensorless. Experimental results have been obtained by a prototype of two modules balancing four series-connected batteries. [ABSTRACT FROM AUTHOR]

The integration of switched-capacitor techniques into multilevel inverters (MLIs) with a dc source string contributes to the boosting of voltage gain, renders it particularly attractive in reducing the number of input dc sources in the series string. However, the recent two-stage MLI topologies suffer from high voltage stress across the backend H-bridge. Addressing this concern, an improved topology, namely the one-switched-capacitor integrated MLI (1SCI-MLI) is proposed in this paper. An extended topology of 1SC-MLI is also established by appropriate incorporation of another switched-capacitor circuit. The two proposed topologies are endowed with voltage boosting capability. They also feature low switch count and low number of dc sources. More importantly, they resolve the high voltage stress problem in the existing counterparts. Their corresponding operational analysis and comparisons with recent MLI topologies are discussed. Simulation and experimental results from a laboratory prototype are presented to validate the effectiveness of the proposed topologies. [ABSTRACT FROM AUTHOR]

Recently multilevel inverters (MLIs) have received wide attention from industry and academia, as they are changing into a viable technology for diverse applications. To produce high-quality output using less switch count, development of novel reduced switch MLI (RS MLI) topologies has been a focus of current research theme. This paper presents design and control of a switched-diode dual source single switch MLI (SDDS MLI). The generalized SDDS MLI is first designed using an asymmetric basic unit. Proposed SDDS MLI requires less switch count and driver circuit count compared with the few recently developed RS MLI topologies. To improve the voltage quality by eliminating targeted low-order harmonics, a modified version of fish swarm optimization algorithm is examined for computing optimum switching angles required to control the SDDS MLI. Moreover, suitability and superiority of the derived algorithm are established by comparing with traditional selective harmonic elimination techniques. The developed topology is investigated through several MATLAB simulations as well as experimental tests in the laboratory applying the modified control approach. [ABSTRACT FROM AUTHOR]

This paper deals with the analysis of the input dc-link voltage ripple in multilevel inverter based on H-bridge and level doubling network (LDN). The LDN is basically a half-bridge fed by a floating capacitor, with voltage self-balancing capability, recalling the concept of a flying capacitor configuration. The amplitude of the LDN voltage ripple is analytically determined considering both the low-order and the switching harmonic components. In particular, peak-to-peak distributions of voltage ripples over the fundamental period are analytically determined, making possible the design of dc-link capacitor relying only on the dc-voltage ripple requirements. The case study makes reference to negligible switching ripple in the output current. It well represents either grid connection or passive load having almost sinusoidal currents. Numerical simulations carried out by MATLAB/Simulink and a complete set of experimental verifications are given to confirm the theoretical developments. [ABSTRACT FROM AUTHOR]

In this paper, a novel structure of switched capacitor converter (SCC) is proposed. First, the basic unit of the proposed SCC is presented. After that, a generalized structure of the proposed SCC is discussed. The presented SCC uses one dc source, several switches, diodes, and capacitors to produce multistep dc boosted output voltage. The capacitors in the SCC can be charged in trinary asymmetrical pattern. A detailed comparative study between the proposed and other recently developed SCC structures is presented. It is shown that the proposed SCC can produce an output voltage level with lower total standing voltage and lower maximum switch stress voltage as compared to most of the suggested SCC structures. Further, a switched capacitor multilevel inverter (SCMLI) based on cross-switched multilevel inverter has been developed and analyzed for symmetric and asymmetric dc source configurations. For fair comparison with the existing SCMLI structures, the overall cost of the structures is compared based on a cost function (CF). The proposed SCMLI provides lower cost function/output voltage level (CF/NL) in comparison with most of the other SCMLI structures for both symmetric and asymmetric dc source configurations. Extensive experimental studies validate the operation and performance of the proposed SCMLI structure. [ABSTRACT FROM AUTHOR]

Automated early detection and identification of switch faults are essential in high-voltage applications. Modular multilevel converter (MMC) is a new and promising topology for such applications. MMC is composed of many identical controlled voltage sources called modules or cells. Each cell may have one or more switches and a switch failure may occur in anyone of these cells. The steady-state normal and fault behavior of a cell voltage will also significantly vary according to the changes in the load current and the fault timing. This makes it a challenging problem to detect and identify such faults as soon as they occur. In this paper, we propose a real-time and highly accurate MMC circuit monitoring system for early fault detection and identification using adaptive one-dimensional convolutional neural networks. The proposed approach is directly applicable to the raw voltage and current data and thus eliminates the need for any feature extraction algorithm, resulting in a highly efficient and reliable system. Simulation results obtained using a four-cell, eight-switch MMC topology demonstrate that the proposed system has a high reliability to avoid any false alarm and achieves a detection probability of 0.989, and average identification probability of 0.997 in less than 100 ms. [ABSTRACT FROM AUTHOR]

This paper presents the topology and modulation technique of a three-phase three-level modified Z-source neutral-point-clamped (MZS-NPC) inverter, which combines a modified Z-source impedance network and a three-phase three-level NPC inverter. The boost factor of the proposed MZS-NPC inverter is twice as high as the three existing representative topologies combing an impedance network with a three-level NPC inverter. A modulation scheme for the proposed topology, based on a maximum boost control method, is designed to achieve the maximum voltage gain with simple implementation and to balance the dc-link neutral-point voltage. A closed-loop control of the ac load voltage in the fuel-cell or photovoltaic applications based on the proposed inverter is realized, in order to supply a desired voltage to the critical load in islanding mode of a microgrid. The boosting ability and operation validity of the proposed topology and modulation technique are demonstrated with simulation and experimental results. [ABSTRACT FROM AUTHOR]

A pulsewidth-modulation bidirectional ac–dc converter (i.e., active rectifier) with dc-fault-blocking and self-pre-charge capabilities is proposed in this paper for low voltage dc (LVdc) applications. The proposed converter, which is named as “H5 + converter,” consists of an H4 bridge, a bidirectional switch, and a transient-voltage-surge (TVS) diode. The bidirectional switch and the TVS diode enable the dc fault blocking and dc bus self-pre-charge, while preserving the low common-mode voltage noise and low leakage current of the converter. Additionally, the proposed H5+ converter has advanced features under a dc-side short-circuit fault, such as fault diagnosis and fault recovery. Operation principles of the proposed converter are presented and analyzed. A down-scaled prototype is built. Experiment results are shown and analyzed, including steady-state waveforms, common-mode performance, start-up dynamics, as well as dc fault blocking, fault diagnosis, and fault recovery. Moreover, the proposed converter is compared with other two dc-fault-blocking converters for LVdc applications, in terms of converter capabilities, required devices, and power switch losses. [ABSTRACT FROM AUTHOR]

In this paper, the performance and reliability of a cost-effective novel integrated power converter (NIPC) are investigated in comparison to the asymmetric half-bridge power converter (AHBPC) for switched reluctance drive (SRD) system. First, with the soft chopping manner, the working modes and voltage equations of NIPC are illustrated to develop the conventional control strategies. Second, given that the power switches are the reliability-critical devices of converters, a novel control strategy is put forward to shorten the operation time and lower the electrical stress of power switches. Besides, the SRD system with NIPC can still operate with the faults of power switches, especially the output torque of faulty phase is not zero when the open-circuit fault happens. But in order to further enlarge the output torque of faulty phase and lower the torque ripple, the fault-tolerance strategy is proposed. Next, to effectively evaluate the topologies from the perspective of reliability, a unified Markov model is introduced to conduct the static and dynamic reliability analysis, illustrating that the reliability of NIPC is evidently higher than AHBPC. Finally, the simulation and experiments on a prototype SRD system are developed to verify the effectiveness of proposed NIPC and corresponding control strategies. [ABSTRACT FROM AUTHOR]

This paper describes a theory to synthesize nonisolated dc–dc converters. It uses the fundamental flux balance equation across the inductors of a converter as a starting point in this synthesis process. The flux balance equations are the linear equations of the input voltage, capacitor voltages, and duty cycle (D). The coefficients of these linear equations can be selected from a finite set of choices. These choices define the converter topologies that are subsequently used to synthesize a converter. The synthesis procedure applies to a converter of multiple order. All the possible converters are identified for a first-order topology. In the case of second-order converters, all the choices of the flux balance equation are defined. Based on these choices, three new quadratic topologies are derived and verified to demonstrate the effectiveness of the theory. The procedure to synthesize a converter from a given voltage conversion ratio is also outlined. [ABSTRACT FROM AUTHOR]

This paper presents a new five-level T-type nested neutral point clamped (T-NNPC) converter. The proposed five-level T-NNPC topology is very attractive for medium-voltage applications as it can work in a wide range of voltages without the need of devices in series, and fewer components compared to the other five-level topologies. A model predictive control (MPC) strategy is also developed for the proposed converter to control the output currents at different output frequencies, and control flying capacitor voltages. A discrete-time model of the converter is developed and the control objectives that are the output currents and flying capacitor voltages are defined regarding switching states. A cost function is defined to minimize the deviation of the predicted values of the control objectives from their desired values. During each sampling time, the best switching state is selected and applied to the converter. The performance of the proposed five-level T-NNPC and the developed MPC strategy is studied in the MATLAB/Simulink environment, and the feasibility of the converter is evaluated experimentally. [ABSTRACT FROM AUTHOR]

High step-up boost converters with coupled inductor have attracted much attention in the fuel cell or photovoltaic grid-connected generation system, however, there are few literatures elaborated on the construction ideas and derivation methods of them. Accordingly, in order to obtain a clear roadmap on the derivation and inner connection of these converters, a comprehensive review and analysis are presented in this paper. First, the basic boost converter with coupled inductor is regarded as the basic topology, and its merits and demerits are analyzed in detail. Then, in order to address these demerits, various step-up techniques are introduced, such as the rectifier circuit, the active-clamped circuit, the multi-winding coupled inductor, and the voltage doubler rectifier; and numerous new topologies are continuously proposed by combinations and equivalent simplifications. In addition to a detailed synthesis of each topology, a comparative and quantitative analysis among some important converters is presented, and the optimal one is chosen to build a 250 W prototype. Finally, based on comparisons and analysis, the main characteristics and inner connections of these high step-up boost converters with coupled inductor are identified and clarified. [ABSTRACT FROM AUTHOR]

Phase-shift full-bridge (PSFB) converter is a widely used topology for high-efficiency and high-power applications, thanks to low voltage/current stress of all components and zero-voltage-switching operation of primary mosfets. The critical drawback of the PSFB converter is hard-switching characteristics of primary mosfets at a very light load, which causes severe thermal explosion and extremely high input power consumption, especially with the latest super-junction mosfet. To minimize the switching loss of the PSFB converter at a very light load, a new optimal dead-time control scheme with burst-mode operation is proposed in this paper and its validity is verified experimentally with the implemented 2.2-kW server power supply unit. [ABSTRACT FROM AUTHOR]

This paper proposes a new family of multilevel inverter topology that is able to generate seven voltage levels by utilizing one or two floating capacitors and 10 power switches. This novel boost switched-capacitor seven-level inverter possesses voltage boosting capability with an achievable maximum voltage level 1.5 times the input direct current (dc) voltage. The generation of higher output voltage does not incur high-voltage stress on any power switch in this topology, as the peak inverse voltages of all power switches do not exceed the input source voltage. In addition, capacitor voltage balancing is not essential since the floating capacitors are effectively balanced during the charging and discharging processes. Furthermore, the proposed topology eliminates the need for multiple isolated dc sources, and a single dc source is sufficient in both its single-phase and three-phase topologies. The operating principle and steady-state analysis of the proposed topology are elaborated. Experimental results from a single-phase prototype are then presented to verify the validity of the proposed topology. [ABSTRACT FROM AUTHOR]

In high-voltage bus-based photovoltaic systems, a power electronic interface is required to manage the power flow in between the photovoltaic (PV) panel, battery, and the high-voltage dc bus. In this paper, a novel three-port dc/dc topology is proposed for this application. Pulsewidth and phase-shift offer two degrees of freedom to effectively regulate the power flows. On the primary side, the input current ripple is reduced due to the interleaved structure. This avoids the usage of the bulky electrolytic capacitors on the PV terminal. On the secondary side, a voltage sixfolder rectifier is employed to boost the step-up ratio. This reduces the transformer's secondary-side turns number. Moreover, the voltage stresses of secondary-side mosfets and diodes are reduced to one-third of the output voltage. Zero-voltage switching and zero-current switching are realized among all power mosfets and diodes, respectively, and in an extended range. A 500-W converter prototype, linking a battery pack, a PV panel, and a 760 V dc bus, is designed and tested to verify the proof-of-concept. Both the circuit functionality and theoretical analysis are validated by the experimental results. [ABSTRACT FROM AUTHOR]

This paper addresses the design of a solid-state bipolar pulsed-power modulator based on a series of stacked power cells that realize a simple and robust structure. Each cell is charged in parallel by an LCC resonant converter independently of the discharging loop. A passive cell-balancing design is implemented. The power cell using insulated gate bipolar transistors (IGBTs) can operate in bypass mode without an additional component, and the circuit operation was analyzed. A simple gate driving method, which provides synchronized gate signals without an extra power source of each gate driver using two control loops and isolation transformers, is implemented for the proposed bipolar pulsed-power modulator based on stacked cells. Moreover, an unexpected gate turn-on problem was solved by an additional off signal. To validate the proposed structure and the gate driving scheme, a three-cell, 1.2-kV, 110-A, 1.5- to 4- $\mu \text{s}$ , 3-kHz laboratory experimental prototype test was conducted. The results proved the reliability of the proposed solid-state bipolar pulsed-power modulator. [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]

This paper presents a single-stage single-switch soft-switching (S6) power factor correction (PFC) converter to enhance the current shaping performance and reduce the total harmonic distortion. This improvement is achieved by the aid of an auxiliary winding which is used to lower the input current harmonics and also achieve soft-switching condition. As a result, the switching losses are reduced and harmonic content of the input current is improved noticeably in comparison to the conventional S6 PFC converter. Also, the total number of semiconductor elements is reduced in the proposed topology which results in lower cost and higher efficiency. The operating modes of the proposed converter are discussed in detail and the design procedure is presented. A 200-kHz prototype of the proposed converter is implemented and the obtained results are provided to verify the converter theoretical analysis and operation. [ABSTRACT FROM AUTHOR]

In order to provide high and extendable power levels for inductive power transfer (IPT) system, a parallel multi-inverter system based on modular inverter is presented. Various power requirements can be implemented by an adjustment of the number of paralleled inverters, which provides a high modularity. A master−slave scheme is employed for the switching-driver signals of parallel inverters, where one acts as a leader while others act as followers. Despite the master−slave scheme, the proposed circuit topology has natural robustness because of the equality in terms of the hardware configuration of each modular inverter. For proper parameters, the output phase (current lagging corresponding voltage) of an inverter is lower than the average of output phase of all inverters, when its output voltage lags behind others, and vice versa. Based on this approach, PI controllers are designed to implement phase synchronization for output voltages of all inverters. An IPT prototype supplied by the proposed parallel multi-inverter with three inverters was designed, built, and tested. Experiments show that the proposed parallel multi-inverter system has not only good circulating current suppression capacity but also excellent performance of phase synchronization. The maximum dc−dc efficiency was 94% at a 35.1 kW receiving power. This paper is accompanied by a Matlab/Simulink file demonstrating phase synchronization control. [ABSTRACT FROM AUTHOR]

This paper proposes a new 7-level inverter topology for induction motor drives. It is a hybrid topology formed by cascading a 5-level active neutral-point-clamped inverter with a 3-level T-type converter. It is obtained using low-voltage semiconductor devices with voltage blocking capability of Vdc/3 and Vdc/6. The topology uses three floating capacitors per phase, which are balanced within a pulsewidth modulation (PWM) switching duration using switching-state redundancies for each pole-voltage level. Topology forms two stacks at the front-end, which requires individual symmetrical dc source. The analysis of switching loss and conduction loss is performed and compared with some of the existing 7-level multi-level inverters reported in various literatures to show the advantages of the proposed topology. Furthermore, the single dc source operation with two stacked capacitors and closed-loop control of neutral-point voltage using symmetrical six-phase induction motor is proposed. The voltage-control algorithms for floating capacitors and dc-link stacked capacitors are proposed, which are independent of load power factor and modulation index. Open-loop V/f and closed-loop rotor field oriented control are performed, and various results at steady and transient states are presented to validate the aforementioned claims. [ABSTRACT FROM AUTHOR]

One of the recent trends in power electronics field is to achieve high efficiency and compact size by using wide bandgap power devices such as silicon carbide (SiC) or gallium nitride switches. This paper compares the efficiency, the motor terminal voltage quality (dv/dt), and the common mode current of the SiC-based variable frequency drives (VFDs) according to the inverter topologies with and without the output filters. For this purpose, both the 2-level (2L) and 3-level (3L) topologies with SiC devices are built and tested. Here, the well-known 2L half-bridge inverter is compared with the well-known 3L T-type neutral point clamped inverter. A dv/dt filter and a sine wave filter have been discussed to satisfy the National Electrical Manufacturers Association standards as well. The experiments have been carried out with a 380-V/60-Hz, 3.7-kW induction motor and the custom designed power stages. Additionally, the experiments with both a 3-m and a 50-m cable length between the VFD and the induction motor are performed and reported. [ABSTRACT FROM AUTHOR]

An improved bridgeless (BL) Cuk converter-based electric vehicle (EV) battery charger with high power factor and increased efficiency is designed and developed in this paper. It provides low cost and high-power-density-based charging solution for the EV. This charger incorporates less number of devices operating over one switching cycle, which reduces the additional conduction loss incurred by a diode bridge rectifier of the conventional charger. Hence, it improves the charger's efficiency. The added advantage of the proposed topology is that the unwanted capacitive coupling loop is removed, as well as the unwanted conduction through the body diode of the inactive switch in the previously developed BL Cuk converter is avoided. This significantly improves the charger's efficiency. For the constant current and constant voltage charging, the commands are synchronized by a flyback converter. The proposed charger draws a sinusoidal current from ac mains and the total harmonic distortion in the supply current is reduced to the limits specified by the IEC 61000-3-2 guidelines. The improved efficiency and power quality indices of the proposed charger are investigated to demonstrate its satisfactory charging operation at all operating conditions. [ABSTRACT FROM AUTHOR]

In this paper, a new soft-switching bridgeless single-phase power factor correction converter is introduced and analyzed. Employing an auxiliary flyback circuit, existing dead angle in the input current is eliminated while softswitching is achieved. The flyback converter processes only small amount of output power. Therefore, conduction losses of its bridge diode and semiconductor devices are low. Also, the auxiliary flyback converter provides soft-switching condition for buck switches. All semiconductors are turned on and off under soft-switching condition. In addition to reduction of switching losses, diode's reverse-recovery problems are eliminated due to soft-switching condition. The proposed approach takes advantage of operating under discontinuous conduction mode to shape the input current into sinusoidal form inherently. Experimental results are reported for a 120-W prototype at 110 Vrms input and 48-V output. The results demonstrate efficiency of 93% at nominal load condition. Furthermore, the input current harmonics fulfill IEC61000-3-2 (Class D) standard as well. [ABSTRACT FROM AUTHOR]

In this paper, a novel noncoupled inductor high voltage gain single-ended primary-inductor converter (SEPIC) is presented. The proposed converter has various advantages, such as lower voltage stress on the switches, noninverting output voltage, high efficiency, and high voltage gain. Also, the introduced converter has a continuous input current which makes it suitable for renewable energy and fuel cell applications. Moreover, high voltage gain is achieved without using any transformer and coupled inductor, thus there is not any voltage overshoot for the switches during the turn-off process. This effect allows low conduction losses by using lower voltage rating switches and also additional clamping circuit is not needed. The control system of the presented converter is simple and the converter can be easily controlled in continuous conduction mode mode operation. Because, the gating pulses for both of the switches are the same and wide output voltage range is achieved only by changing the duty cycle. Furthermore, the number of the components compared to the other noncoupled inductor, SEPIC-based converters which provide near voltage gain to the proposed converter, is reduced. The detailed operation of the introduced converter and design considerations are discussed. Experimental results are presented to verify the performance of the proposed dc–dc converter. [ABSTRACT FROM AUTHOR]

This paper presents an approach for dealing with the control of five-level, diode-clamped rectifiers. The control of such converters is challenging, as voltage balancing among capacitors is not a trivial task. Some of the existing approaches that cope with this problem use specific modifications of one of the traditional modulation techniques, such as using redundant vectors in space vector modulation (SVM). The main feature of the proposed technique is that part of the modulation is considered in the system equations and, in this way, the voltage balance can be solved designing a specific controller for this problem. As a result, several levels are used within a switching period. Furthermore, it is shown that the proposed approach hardly affects the control of active and reactive powers and total dc-link voltage in such a way that the well-known direct power control can be applied. As a consequence, the resultant modulation stage is simpler than other techniques based on, e.g., SVM. The effectiveness and good performance of the system under the proposed control approach are validated by both simulation and experimental results. [ABSTRACT FROM AUTHOR]

Thanks to the favorable advantage of low cost, integrated three-port dc–dc converters with reduced switches have attracted extensive attention. In order to provide more new topologies, this paper aims to propose a programmable topology derivation method, which effectively simplifies the cumbersome process of the conventional combination method. Instead of the manual connection and examination, the proposed alternative can quickly and rigorously derive multiple viable integrated three-port dc–dc topologies from a great number of possible connections with the aid of computer program. Besides, generalized analysis is also accomplished, with which performance characteristics of all derived converters are simultaneously obtained and then a comprehensive comparison can be easily conducted to select a preferred one for the practical application. Finally, an example-specific application with one input and two outputs is given, with topology selection, design, and experimental results demonstrated in detail. [ABSTRACT FROM AUTHOR]

The three-level Vienna rectifier is an attractive topology for power factor correction applications. However, for practical high-frequency applications, the nonlinearity caused by snubber circuit and parasitic capacitance of Vienna rectifier's switching device will distort input current. This paper proposes a carrier-based discontinuous space-vector modulation (CB-DSVM) method with varying clamped area for Vienna rectifier in high switching frequency applications. The equivalent circuit of Vienna rectifier considering the nonlinear factors is built and the effect of pulse shaping around current zero-crossing point is investigated. The voltage errors caused by the nonlinearity of switching device will distort terminal voltage, which mainly appears at the zero-crossing time. A DSVM method with the fixed clamped area around the zero-crossing point is proposed to reduce the voltage errors and then the simplified CB-DSVM method with varying clamped area by adding a clamped factor to the judging conditions is further studied, which will reduce low-order harmonics of the CB-DSVM method. Simulations and experiments are carried out in a 600 W Vienna rectifier platform, which demonstrates the validity of the proposed method. Compared with the CB-SVM method, the proposed CB-DSVM method with varying clamped area has comparative neutral-point voltage balancing ability and better input current quality. [ABSTRACT FROM AUTHOR]

A novel single-stage high-frequency link three-phase ($3\phi$) inverter along with a modulation strategy is presented in this paper. The topology is targeted for grid integration of utility scale renewable and alternative energy sources like solar, fuel cell, and wind, where the power flow is unidirectional (from dc to ac). The primary side converter has a $3\phi$ voltage source inverter (VSI) structure along with an additional half-bridge leg. Sinusoidal pulsewidth modulation is implemented in the primary side converter. The three legs of the primary side VSI are zero voltage switched (ZVS) for most part of the line cycle. The additional half bridge leg is ZVS over the complete line cycle. The active switches in secondary side converter are line frequency switched and thus results in negligible switching loss. The converter switching process is described in detail to show the soft-switching of the primary side converter using the device capacitances and leakage inductances of the high-frequency transformers (HFTs). The HFT galvanic isolation results in high power density. A 4-kW laboratory scale hardware prototype is built and tested with the proposed modulation strategy. The experimental results are presented to verify the converter operation. [ABSTRACT FROM AUTHOR]

This paper discussed an active-bridge-active-clamp (ABAC) topology that is suitable for highpower more-electric-aircraft applications. Though conventional modulation techniques can be applied to ABAC converters, they present drawbacks, such as increased low-voltage (LV) current ripple and limited power transfer capability. To address these problems, a phase-shift-modulation (PSM) scheme is proposed to provide clean dc terminal current at the LV side while maintaining high power transfer capability and efficiency in a wide operating range. The proposed PSM has a complete switching harmonics cancellation on the LV terminals independent of the operating conditions. This results in high quality power without any ac components, thus minimizing passive filtering. In addition, when terminal voltages vary from their nominal values, the proposed PSM can improve the maximum power transfer capability of the ABAC converter compared to the conventional approach. The theoretical claims are validated by both simulation and experimental results on a 10-kW 270-V/28-V ABAC converter. [ABSTRACT FROM AUTHOR]

In this paper, a new zero-voltage zero-current transition (ZVZCT) boost converter using coupled inductors is proposed. The feature of this topology is: the main switch can be switched on with ZVZCT, and off with zero-voltage switching, without any voltage and current stress. The auxiliary switch is turned on with zero-current switching. Other semiconductor devices can also achieve soft switching (SS). Due to the existence of the coupling effect, the current impact of the auxiliary switch is completely suppressed when it is turned off. Lower input current and output voltage in the interval of the switch-off for the auxiliary switch are just equivalent to running at a low power level, which is an additional advantage of the coupled inductor ZVZCT solution. Another advantage of the topology is that the SS condition of the main switch for each specific load can be effectively optimized just by setting the ratio of coupling inductance corresponding to the circuit design and application load. Thus, the topology design can be improved to adapt to different load types. A 100 kHz experimental prototype has been verified, different load for 1 and 0.4 kW optimization comparison has been presented, and the case without optimization is also observed. [ABSTRACT FROM AUTHOR]

In this paper, a systematic and analytical study of non-isolated topologies belonging to the family of reduced redundant power processing (R2P2) converters is presented. Based on this study, all the non-isolated R2P2 topologies that can be implemented in reality are derived. Detailed examples clarify all possible cases of this analysis. In addition to this, the voltage ratio and the efficiency for each one of the R2P2 configurations are calculated, being further illustrated with examples. A comparison among configurations is also discussed with criteria the high step-up voltage gain and efficiency, aiming for high-power applications. One of these R2P2 converters is selected for further examination, as the most suitable for such applications. The theoretical analysis, as well as the calculations of the step-up voltage ratio and efficiency of the selected converter, is compared to experimental results conducted on a 2-kW laboratory prototype designed to operate in various step-up voltage ratios and in a high-power range, proving the effectiveness of the proposed investigation. [ABSTRACT FROM AUTHOR]

Modules with series and parallel connectivity add new features and operation modes to modular multilevel converters (MMCs). Compared to full- and half-bridges, the series/parallel modules allow sensorless module balancing and reduce conduction loss with the same semiconductor area. However, in high-voltage applications with limited switching rates, the sensorless operation of the series/parallel modules suffers from large charge-balancing currents. This paper introduces a series/parallel module variant with a small port inductor. The port inductor suppresses the charge-balancing current despite low switching rates. We also propose a carrier-based modulation framework and show the importance of the carrier assignment in terms of efficiency and balancing. The proposed module and the modulation method are verified on a lab setup with module switching rates down to 200 Hz. The module voltages are kept within a narrow band with the charge-balancing currents below 5% of the arm current. The experimental results show practicality and advantages of the new series/parallel modules in high-voltage MMC applications. [ABSTRACT FROM AUTHOR]

Modern GPUs feature an increasing number of streaming multiprocessors (SMs) to boost system throughput. How to construct an efficient and scalable network-on-chip (NoC) for future high-performance GPUs is particularly critical. Although a mesh network is a widely used NoC topology in manycore CPUs for scalability and simplicity reasons, it is ill-suited to GPUs because of the many-to-few-to-many traffic pattern observed in GPU-compute workloads. Although a crossbar NoC is a natural fit, it does not scale to large SM counts while operating at high frequency. In this paper, we propose the converge-diverge crossbar (CD-Xbar) network with round-robin routing and topology-aware concurrent thread array (CTA) scheduling. CD-Xbar consists of two types of crossbars, a local crossbar and a global crossbar. A local crossbar converges input ports from the SMs into so-called converged ports; the global crossbar diverges these converged ports to the last-level cache (LLC) slices and memory controllers. CD-Xbar provides routing path diversity through the converged ports. Round-robin routing and topology-aware CTA scheduling balance network traffic among the converged ports within a local crossbar and across crossbars, respectively. Compared to a mesh with the same bisection bandwidth, CD-Xbar reduces NoC active silicon area and power consumption by 52.5 and 48.5 percent, respectively, while at the same time improving performance by 13.9 percent on average. CD-Xbar performs within 2.9 percent of an idealized fully-connected crossbar. We further demonstrate CD-Xbar's scalability, flexibility and improved performance per Watt (by 17.1 percent) over state-of-the-art GPU NoCs which are highly customized and non-scalable. [ABSTRACT FROM AUTHOR]

Cascaded H-bridge (CHB) is a promising topology for medium-voltage high-power applications. CHB consists of low-power H-bridge modules in each phase, and these modules are connected in a cascade manner to achieve multilevel operation. However, CHB requires a phase-shifting transformer with multiple secondary windings to generate an isolated dc source for each module, and this requirement increases the overall system cost. In this paper, a series connection of low-power modules is employed to realize a new power converter called a series-connected multilevel converter. Each phase of the proposed topology requires a single isolated dc source. Hence, the required number of secondary windings is considerably reduced. This approach also minimizes the complexity and cost of the overall system. The operation of the proposed topology is presented by using three-level neutral point clamped modules in each phase. Model predictive control (MPC) is employed to control the dc-bus capacitor voltage and output currents of the proposed topology. A discrete-time mathematical model of the proposed topology is also developed to predict the future behavior of control variables. The performance of the proposed topology with MPC is verified through MATLAB simulations and a scaled-down laboratory prototype. [ABSTRACT FROM AUTHOR]

In this paper, a fully soft-switched bidirectional dc–dc converter is proposed. All semiconductor devices are soft switched, while its control circuit remains pulsewidth modulated. This condition is achieved only by one auxiliary switch. So, the proposed topology has less complexity in comparison with other similar structures. The energy conversion through the proposed topology during buck and boost modes is highly efficient due to achieved soft-switching condition. The auxiliary circuit operates once during each switching cycle. The converter is analyzed and a 250-W laboratory prototype of the proposed converter is constructed. The experimental results are presented that confirm the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper proposes two coupled-inductors-based Z-source networks, called the modified series and tapped switched-coupled-inductors quasi-Z-source networks (mSSCL-qZSN and mTSCL-qZSN, respectively). These networks offer high voltage gains with less-than-unity winding turn ratios $(n < {\text{1)}}$ , resulting in a reduced inductive element size. Other advantages include a less number of active components and their lower ratings and a higher efficiency. In addition, a lower magnetic core size is required for the proposed ZSNs due to the lower peak magnetizing current. The performance principles and detailed comparative analysis are provided and confirmed through experiments on a 200-W dc–dc converter. [ABSTRACT FROM AUTHOR]

Most fuel cell electric vehicles require wide voltage-gain DC–DC converters to increase and equalize the relatively low voltage of fuel cell stacks with DC link bus or energy-storage devices, such as supercapacitors or batteries. This paper proposes two new non-isolated DC–DC converters suitable for such applications, which can be extended to other electric vehicles as well. The proposed converters combine the main characteristics of both quadratic Boost and Ćuk converters, offering high step-up voltage and control simplicity using only one ground referenced active power switch. Additionally, the proposed topologies present reduced voltage stress across the active power switch when compared to other boost converters. Considerations about the design of the proposed converters will also be presented. Experimental results obtained using a laboratory prototype validate the effectiveness and feasibility of the proposed topologies and its suitability for fuel cell electric vehicles. [ABSTRACT FROM AUTHOR]

This paper presents a generalized analysis of the Class-E power amplifier (PA) with a shunt capacitance and a shunt filter, leading to a revelation of a unique design flexibility that can be exploited either to extend the maximum operating frequency of the PA or to allow the use of larger active devices with higher power handling capability. The proposed PA fulfills zero voltage switching (ZVS) and zero voltage derivative switching (ZVDS) conditions, resulting in a theoretical dc-to-RF efficiency of 100%. Explicit design equations for the load-network parameters are derived, and the analytical results are confirmed by harmonic-balance simulations. Two PA prototypes were constructed with one designed at low frequency and the other at high frequency. The first PA, which employs a MOSFET and a lumped-element load-network, delivered a peak drain efficiency $(\!D\!E)$ of 93.3% and a peak output power of 37 dBm at 1 MHz. The second PA, which employs a GaN HEMT and a transmission-line (TL) load-network to provide the drain of the transistor with the required load impedances at the fundamental frequency as well as even and odd harmonic frequencies, delivered a peak $D\!E$ of 90.2% and a peak output power of 39.8 dBm at 1.37 GHz. [ABSTRACT FROM AUTHOR]

Power conditioning system (PCS) is the crucial component of superconducting magnetic storage system (SMES), which determines its power control performance and ability. This paper investigates the feasibility of applying Z source converter (ZSC) as the PCS for SMES. A ZSC-based PCS (ZSC-PCS) for SMES is presented, parameter design methods are analyzed, and a novel minimum power losses control scheme is proposed. By dynamically regulating open zero vector duty ratio to its minimum required level, the ZSC-PCS can enlarge both active and reactive power capability of SMES with lowest power losses. The feasibility of the proposed approach is verified by the experimental results on a kVA scale prototype. [ABSTRACT FROM AUTHOR]

A multiphase-interleaved non-isolated high step-up dc/dc resonant converter for high-current applications with wide load range is proposed in this paper. The converter consists of an inverter stage with multiple resonant inverters in parallel interleaving operation that is cascaded to a common diode–capacitor rectifier stage. The topology of the inverter stage is a variation of class E inverter, which is designed for voltage boosting and of which the voltage gain is insensitive to load change. The rectifier stage comprises multiple pairs (correlated to the number of inverters in parallel) of diodes in parallel and a small output capacitor, which makes it simple to implement and of low cost. Together, the voltage gain variance of the converter can be confined within a small value and zero voltage switching operation can be maintained over a wide load range. A detailed mathematical analysis of the proposed converter is conducted for systematizing its design. A prototype of the proposed converter with an input voltage of 23.6 V, a rated output voltage of 190 V, and a rated output power of 80 W at 486 kHz is constructed for verification. A frequency controller is implemented to achieve fine regulation of the output voltage. [ABSTRACT FROM AUTHOR]

In this paper, a highly efficient isolated resonant converter with a novel modulation method is proposed for delivering power from photovoltaic (PV) modules to the dc microgrid. The proposed modulation method allows the converter to boost low input voltages and regulate a wide input voltage range. The converter design is based on a series resonant converter (SRC) that operates at the resonant frequency to achieve highest efficiency under nominal input voltage condition. Under shadowed or low irradiance conditions of PV panels, the converter will operate with the proposed “double-pulse duty cycle” modulation method to step up the voltage for the dc microgrid connection. With the proposed modulation method, the output switches serve for both synchronous rectification and voltage boost function. This method enables a higher voltage boost ratio than the SRC without adding additional switches while operating at the resonant frequency. A 300-W hardware prototype with gallium-nitride devices is built to verify the performance of the proposed converter and modulation method. The converter achieved a peak efficiency of 98.9% and a California Energy Commission weighted efficiency of 98.7% under nominal input voltage condition. [ABSTRACT FROM AUTHOR]

This paper investigates basic stability properties of the three-level flying-capacitor Buck converter when operated under current-mode control (CMC). The proposed analysis is developed for both peak CMC (P-CMC) and valley CMC (V-CMC), and addresses both the static instability of the inductor current and the flying capacitor (FC) voltage runaway phenomenon. Conditions for avoiding current subharmonic oscillations are derived first, along with the expressions of the minimal compensation ramp, which guarantee current stability throughout the entire operating range. As for the stability of the FC voltage, P-CMC results to be inherently unstable unless the converter operates with a relatively large peak-to-peak inductor-current ripple, a feature not yet recognized in the literature. However, V-CMC results to be inherently stable once the static instability of the current is eliminated with an external compensating ramp—a property that has been highlighted in the literature but never formally proven. The proposed analysis is verified both using a simulation model and experimentally using a 3.3-V, 500-mA, 500-kHz prototype. [ABSTRACT FROM AUTHOR]

This paper proposes a novel open-winding brushless doubly-fed reluctance generator (OW-BDFRG) with dual two-level converters in order to reduce the converter rating and switching frequency for large-scale wind turbine applications. The new converter topology is equivalent to a three-level converter directly connected to the control winding of typical BDFRG. The OW-BDFRG system with this topology structure requires lower converter rating and switching frequency, and has a more flexible control mode, better operation performance, and fault redundancy capability. For the OW-BDFRG, this paper also proposes a new control scheme combining direct power control (DPC) with sliding mode variable structure (SMVS) control to implement the power tracking. The voltage-vector switching table of DPC is redesigned according to the error signals of active and reactive powers of the power winding, as well as the sector location of control winding flux. The active and reactive powers of the OW-BDFRG can be directly decoupled and independently controlled by properly selecting the switching voltage vectors. The novelty of this paper lies in an OW-BDFRG topology driven by dual two-level converters to improve the system characteristics, and the use of SMVS control to improve the DPC accuracy and robustness to parameter variations. Finally, the effectiveness of the proposed system is verified through simulation and experimental studies. [ABSTRACT FROM AUTHOR]

The hybrid modular multilevel converter with cascaded full bridges (HMMC-CFB) is a recently proposed dc fault tolerant converter topology for high-power applications. It has a director part (DP) consisting of a series of connected half-bridge submodules, and a wave-shaping part (WSP) composed of a series of connected full-bridge submodules (FBSMs). The submodules in DP avoid high voltage stresses and improve synchronization between DP and WSP by slowing down the change rate of DP output voltage. This slowdown is achieved by using a trapezoidal reference signal for DP. The WSP attenuates the voltage harmonics produced by DP. However, the energy exchanged by WSP changes with modulation index, which may cause improper voltage regulation of the submodule capacitors. This paper proposes a new control technique to regulate the energy exchanged by WSP, which uses a variable slope trapezoidal reference signal of DP. To obtain this slope, the feedforward and feedback controllers are used. The feedforward controller gives the value of slope depending on the modulation index (mv) to keep the energy exchanged by WSP nearly equal to zero, whereas the losses and nonideality of the converter are taken care of by the feedback controller. This technique guarantees proper voltage regulation of the submodule capacitors for all modulation indices. The efficacy of the proposed technique is confirmed using simulations and experimentations. This paper also presents a circulating current suppressing controller for HMMC-CFB. The proposed control schemes and dc fault tolerant capability of HMMC-CFB are tested on a grid-connected model built in PSCAD. [ABSTRACT FROM AUTHOR]

This paper investigates the problem of sensor-network-based distributed control for large-scale networked control systems, in which the communication constraint and topology switching problems are addressed. In the considered system, a discrete-time interconnected process is controlled by a network of sensors, controllers, and actuators that collect information about the plant, and apply control actions to manage the plant dynamics. The motivation for this paper is that the communication between the plant network and the controller network can be exploited for the system-wide purpose. To deal with the communication constraint problem, strategies such as the event-based communication and logarithmic quantization are applied. Furthermore, in a networked environment, the real-time information of the topology switching is not always available at the controller network side, hence a bunch of synchronous/asynchronous controllers are designed such that the closed-loop system is exponentially stable and achieves a prescribed H_\infty disturbance attenuation level. Finally, an illustrative example on a benchmark continuous stirred-tank reactor system is presented to demonstrate the effectiveness of the proposed new control technique. [ABSTRACT FROM PUBLISHER]

A three-phase three-level (TPTL) converter is an optimal alternative for high-input and high-power dc/dc conversion system. The voltage stress on the primary switch is only half of the input voltage due to its three-level (TL) structure, and the current rating of power devices can be reduced by the three-phase configuration. To achieve soft switching and improve efficiency, the resonant tank can be introduced to optimize the performance of the converter. In this paper, a novel TPTL LC-type series resonant converter with few switches and simple configuration is proposed. The voltage stress on all switches can be reduced to the half of the input voltage, and the voltage across output rectifiers is clamped to the output voltage; as a result, the proposed converter is suitable for high-input/output applications. Meanwhile, the ripple frequency of the output current can be increased significantly, resulting in a reduced filter requirement. Variable frequency control strategy is adopted in order to obtain zero-voltage switching for all switches and zero-current switching for all rectifier diodes in wide input voltage and load range. In this paper, the comprehensive analysis on the proposed converter is carried out, including the operation mode classification, the operating mechanism under different operation mode, along with the circuit model, and gain characteristics of the converter by the fundamental harmonic analysis. Experimental results from a 440–590 V input and 400 V/5 A output are presented to verify the theoretical analysis and the performance of the converter. [ABSTRACT FROM AUTHOR]

In this paper, a new space vector pulse width modulation method to extend the linear modulation range of a cascaded five level inverter topology with a single dc supply is presented. Using this method, the inverter can be controlled linearly and the peak phase fundamental output voltage of the inverter can be increased from 0.577 to 0.637 V\text{dc} without increasing the dc bus voltage and without exceeding the induction motor voltage rating. This new technique makes use of cascaded inverter pole voltage redundancy and property of the space vector structure for its operation. Using this, the induction motor drive can be operated till the full speed range (0–50 Hz) with the elimination of lower order harmonics in the phase voltage and phase current. The five-level topology presented in this paper is realized by cascading a two-level inverter and two full bridge modules with floating capacitors. The inverter topology and its operation for extending the modulation range is analyzed extensively. Simulation and experimental results for both steady-state and dynamic operating conditions are presented in this paper. [ABSTRACT FROM AUTHOR]

This paper extends the voltage-doubler concept to the single-phase SEPIC rectifier in discontinuous conduction mode and, as a consequence, novel rectifiers are proposed. A comparison with the classic SEPIC rectifier shows that the proposed converters can either provide reduced voltage stress on the semiconductors for the same output voltage level or supply double the gain of the output voltage with the same voltage stress. The proposed voltage-doubler SEPIC rectifiers provide a high power factor with no current control and they can be applied in order to improve the static gain of the structure, which can make the SEPIC rectifier suitable for applications that require a high voltage level. In this paper, the generic structure based on a three-state switch, four different implementations of the proposed concept (including bridgeless structures), steady-state analysis, a dynamic model, system control, and experimental results are presented. The proposed rectifiers were verified by experimental results obtained with a prototype built with the following specifications: 1000 W output power, 220 V input voltage, 400 V output voltage, and 50 kHz switching frequency. Peak efficiency of 95.84%, THD of 2%, and power factor of 0.9997 were obtained and, most importantly, double the gain of the output voltage was verified. [ABSTRACT FROM AUTHOR]

The leaderless consensus problem in a class of high-order multiagent systems with Lipschitz nonlinearities is studied in this paper. Despite existing leaderless consensus protocols devoted to high-order multiagent systems with Lipschitz nonlinearities, the proposed protocol in this paper guarantees achieving consensus in networks of agents with jointly connected topologies. To achieve this goal, first a consensus protocol for high-order multiagent systems with general linear models is proposed. By introducing a common Lyapunov candidate for the set of switching topologies and based on the Cauchy convergence criterion, achieving consensus under the proposed protocol is studied. Then, sufficient conditions are derived under which the results are extended to the case of Lipschitz nonlinearities in agents models. Numerical examples validate the proposed consensus protocol. [ABSTRACT FROM PUBLISHER]

For the conventional PFC rectifiers, the high efficiency cannot be achieved over a wide input range, and the efficiency will be greatly decreased at low-input voltages. In order to overcome the efficiency bottleneck under low-line input, a flexible mode bridgeless boost power factor correction (PFC) rectifier is proposed in this paper. According to the input voltage, the proposed rectifier can be flexibly adapted to the suitable operating mode to obtain the maximum efficiency. Meanwhile, the circuit components can be reused by different operating modes, so the extra cost is low. In the proposed rectifier, a back-to-back bridgeless boost PFC topology is adopted at high-line conditions and a three-level bridgeless boost PFC topology is rebuilt to reduce the switching losses at low-line conditions. Compared with the traditional bridgeless boost PFC rectifier, an extra low-voltage bidirectional switch (usually composed of two switches) is added, so the increased cost is low. In addition, the low common-mode noise can be achieved at both high- and low-line conditions due to the direct connection between the input mains and the output electrolytic capacitor. The detailed principle analysis about the proposed rectifier is presented in this paper. Finally, an experimental prototype is built to verify the feasibility and the effectiveness of the proposed topology. [ABSTRACT FROM AUTHOR]