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Reduced switch active phase converters (APC) are cost-effective solutions for running three-phase loads from single-phase grids. This paper proposes a novel auxiliary-capacitor-based APC (AC-APC) for this application. The combination of the topological location of the auxiliary capacitor and the control of the AC-APC reduces current stress on the semiconductor devices. In this paper, a selection criterion for the optimal auxiliary capacitor value is formulated to reduce the device currents in such a way that the overall efficiency is enhanced. This paper presents a comparative analysis of converter volt-ampere (VA) rating and device power loss for conventional H-bridge active front-end and inverter-based topology, APC, and AC-APC. To evaluate the efficacy of the proposed AC-APC, an experimental study is conducted on the APC and the AC-APC feeding a 3-hp three-phase induction motor. At a full load of $\text{2.5}\,\text{kW}$ and $\text{0.8 } \text{power factor}$ , the measured maximum efficiency of the AC-APC is $2\%$ higher than that of the APC. Analytical evaluation of converter currents and device power loss are in close agreement with experimental observations. [ABSTRACT FROM AUTHOR]

This paper proposes a new developed switched-capacitor converter to achieve high-voltage pulses with adjustable voltage level and frequency. The proposed topology generates repetitive high-voltage pulses by using low-voltage power supply with reduced number of components, including power semiconductors and capacitor. Therefore, a converter based on switched-capacitor units with high voltage gain and high efficiency can be achieved. Operation principles and design steps of the converter as well as comparative study with conventional converters are described in this paper. Finally, simulation and experimental results of a two-stage structure of the proposed circuit validate the operation principles and features of this topology. [ABSTRACT FROM AUTHOR]

This paper presents three unidirectional step-up ac–dc converter topologies with voltage multiplication on their outputs. The first topology is the hybrid boost rectifier and the other two are novel bridgeless structures, all based on the integration of boost rectifier and the ladder switched-capacitor (SC) cell. The new hybrid structures provide high voltage gain with low voltage stress across the switches, high-power factor, and output voltage regulation. This paper presents the principle of operation, steady-state and dynamic analysis, design methodology, and experimental verification. A different approach is also presented for the design methodology of the SC cell and for the analysis of its influence on the dynamic model. Three 1000-W prototypes with a 220-V input voltage, 800-V output voltage, and 100-kHz switching frequency were designed to corroborate the theoretical study. The best efficiency was 97.1$\%$ in the proposed bridgeless versions and the voltage stress across the switches stands around 400 V. Furthermore, a comparison between the proposed structures and previous topologies is also presented. [ABSTRACT FROM PUBLISHER]

Circuit analysis and design criteria of a two-phase bidirectional converter with high voltage gain are presented in this paper. The operating principle of the forward or reverse mode is similar to that of the conventional buck or boost converter. Compared with the conventional converter, the switch stresses can be reduced significantly depending on the operating region of the voltage ratio in the two-phase converter. The power losses can also be reduced due to the use of low-voltage rating switches. The derivate converters are discussed to demonstrate the advantages of the proposed topology. A 200 W/1 MHz two-phase prototype converter with gallium nitride (GaN) devices is built and tested to verify the feasibility. [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]

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]

This paper presents a three-phase open-end winding induction motor drive. The drive consists of a three-phase induction machine with open stator phase windings and dual-bridge inverter supplied from a single dc voltage source. To achieve multilevel output voltage waveforms, a floating capacitor bank is used for the second of the dual bridges. The capacitor voltage is regulated using redundant switching states at half of the main dc-link voltage. This particular voltage ratio (2:1) is used to create a multilevel output voltage waveform with three levels. A modified modulation scheme is used to improve the waveform quality of this dual inverter. This paper also compares the losses in the dual-inverter system in contrast with a single-sided three-level neutral point clamped converter. Finally, detailed simulation and experimental results are presented for the motor drive operating as an open-loop v /f controlled motor drive and as a closed-loop field-oriented motor controller. [ABSTRACT FROM PUBLISHER]

Switched-capacitor converter (SCC) featuring high efficiency and power density has attracted industry interest, but weak output voltage regulation hinders its application. This paper presents an optimized phase-shift (PS) control strategy for a bridge modular SCC, utilized in energy storage system, to obtain continuous conversion ratio and high-efficiency operation. By employing a small inductor as current buffer, the control strategy could be implemented to regulate output voltage conveniently with excellent steady and dynamic performance in step-down mode as well as step-up mode. Most importantly, the high-efficiency operation mechanism never reported before is revealed here. Correspondingly, the active circumfluence could be controlled through optimizing the range of PS time, which will avoid the loss in circuit self. Meanwhile, the soft-switching conditions of all the switches are comprehensively analyzed and soft-switching operations are achieved according to the logic timing control of the power devices, improving efficiency further. Finally, the prototype of the proposed converter was built and the experimental results validated the principle and features of the conversion method. [ABSTRACT FROM AUTHOR]

Conventional two-level as well as multilevel voltage-source-inverter topologies with a hexagonal voltage-space vector structure generate low-order harmonics in the machine terminal voltages when operated beyond the linear modulation range in variable speed drive application. Progressing from hexagonal to a higher sided polygonal voltage-space-vector structure (VSVS) suppresses significant low-order harmonics throughout the modulation range. In addition, the linear modulation range will also be enhanced very near to the base speed. In this paper, for the first time, the generation of a multilevel 24-sided VSVS using a single dc source for induction-motor drives is proposed. A cascaded topology with a dc-source-fed flying-capacitor inverter and two low-voltage capacitor-fed H-bridge cells forms the power circuit. The features and advantages of the proposed scheme are validated through experimental results and discussions. [ABSTRACT FROM AUTHOR]

In this paper, a family of automatic interleaved Dickson switched-capacitor converters (AIDSCC) and its zero-voltage switching (ZVS) resonant configuration are proposed. Different from the traditional Dickson switched-capacitor converter, the AIDSCC has symmetrical configuration with the features of automatic interleaved input current, small output voltage ripple, and lower peak capacitor voltage stress. To improve the line regulation capability, one small resonant inductor is inserted and two bulky capacitor banks are replaced by two much smaller resonant capacitors, forming the resonant AIDSCC. The transistors are ZVS turned on and diodes are zero-current switching turned off by operating above the resonance. With frequency modulation within a reasonable range, the voltage-gain range of the resonant AIDSCC is expanded significantly, while sacrificing the maximum efficiency due to the higher conduction loss. A 3X AIDSCC and a 3X resonant AIDSCC below 140 W were built to verify the analysis. [ABSTRACT FROM AUTHOR]

Microinverters operating into the single-phase grid from new energy source with low-voltage output face the challenges of efficiency bottleneck and twice-line-frequency variation. This paper proposed a multilevel inverter based on bridge modular switched-capacitor (BMSC) circuits with its superiority in conversion efficiency and power density. The topology is composed of dc–dc and dc–ac stages with independent control for each stage, aiming to improve system stability and simplify the control method. The BMSC dc–dc stage, which can be expanded to synthesize more levels, not only features multilevel voltage gain but also partially replaces the original bulk input capacitor and functions as an active energy buffer to enhance power-decoupling ability between dc and ac sides. In dc–ac stage, the control strategy of optimized unipolar frequency doubling sine-wave pulse width modulation is proposed to improve the quality of output waveform. Meanwhile, the multilevel voltage phase has been optimized to further reduce the power loss. Finally, a prototype has been built and tested. Associated with the simulation, the experimental results validate the practicability of these analyses. [ABSTRACT FROM PUBLISHER]

Direct current voltages unbalance of respective power cells is an inherent and critical problem in a cascaded multilevel converter, which is widely used in the solid-state transformer. In this paper, an n -dimension space vector pulse width modulation is presented to address this issue in a three-level H-bridge-based cascaded multilevel converter. This algorithm utilizes the redundant switching pairs of the inner cell and the redundant vectors of mutual cells to balance capacitors’ and cells’ voltages. Meanwhile, a smooth vector transition strategy is included in this algorithm to avoid the level-skip phenomenon. The calculation processes are analyzed in one-cell, two-cells, and three-cells modes, respectively. It is simple, calculable, and flexible to extend in n-cells mode. Finally, the voltage balancing capacity of the inner cell and mutual cells with smooth level transition are verified by simulations and experiments not only at startup but also with unbalanced loads. [ABSTRACT FROM PUBLISHER]

A nonisolated single-stage electronic lighting system with a high power factor for driving power light-emitting diodes (LEDs) is proposed in this paper. The presented topology is based on the integration of a bridgeless boost rectifier with a nonresonant half-bridge converter. Accurate steady-state analyses of the nonresonant- and resonant-based circuits are reported, serving as the basis for designing the lighting systems. The LEDs current is adjusted by means of frequency modulation, being the converter switches driven by complementary symmetrical signals. A small-signal analysis is detailed for the proposed nonresonant scheme, providing fundamental information regarding its dynamic behavior. Also, a step-by-step design procedure based on the performed mathematical analysis is elaborated, allowing the adequate design of the proposed lighting system. In order to confirm the validity and the feasibility of the proposed converter, experimental results for a 42-W, 127- \rmV{\rm{rms}}, 50-kHz, 94.2% peak efficiency prototype are presented. [ABSTRACT FROM PUBLISHER]

This paper presents an optimized topology of 3-$\phi$ , multilevel inverter (MLI) configuration for five or higher level operation with reduced switch count. The proposed solution consists of two basic units (BUs) of multilevel converter and a T-structured 3-level inverter (3-LI). Both BUs are equally shared by the three phases maintaining symmetry among the phases. Moreover, for a higher level operation of the proposed MLI, the modifications required are at two BUs only and not at three legs of the inverter. It further helps in reducing the requirement of extra components for higher level operation compared to the conventional solutions. Furthermore, the topology also has the benefits of reduced switching and conduction loss. An algorithm is also devised to generate the switching pulses for the BUs and the 3-LI, using a carrier-based space vector modulation technique. Presented topology is compared with other existing topologies to prove its advantage. All the details regarding the operating modes and pulse width modulation techniques employed for the proposed system are given and supported by the simulation and experimental results. [ABSTRACT FROM AUTHOR]

Adding the auxiliary switches to the conventional H-bridge inverter is an effective way to eliminate the leakage current for transformerless PV systems, such as H5, H6, etc. Inspired by the newly developed embedded-switch H6 topology, a novel embedded-switch inverter (ESI) is proposed in this paper for three-phase transformerless PV systems. First, the operation principle and characteristics of the proposed ESI are analyzed. Second, the common-mode model of the three-phase ESI is established, based on which the main factors that affect the leakage current are discussed. The finding reveals that the switching states with conventional modulation strategy result in high-frequency common-mode voltage, which is the source of leakage current. In order to solve the problem, a new modulation strategy is presented for ESI to eliminate the high-frequency leakage current. Finally, the time-domain simulation and the experimental tests are carried out. The results verify the effectiveness of the proposed solution. [ABSTRACT FROM AUTHOR]

This paper proposes an interleaved-stage ac–dc bidirectional power converter topology feasible to medium-voltage railway systems. It is based on an arrangement that uses input-series-output-parallel configuration with identical power modules. Each module consists of two interleaved legs employing coupled windings so that it is possible to connect a medium-frequency transformer. The topology conception is presented, followed by the adopted control and modulation technique. An estimation of semiconductor losses is also discussed, while a comparative analysis by means of simulation results validates the improved performance of the introduced approach if compared with similar solutions. The topology results are obtainedt through a medium-voltage high-power railway application, demonstrating the converter functionalities and performance under both steady-state and dynamic conditions. It is then possible to state that good performance in terms of efficiency is achieved even though the power stage presents higher component count if compared with the topology that presents the best result, thus making it suitable to high-power ac–dc machine drive applications. [ABSTRACT FROM AUTHOR]

In this paper, a soft-switching topology is proposed for the bidirectional dc–dc converter. In order to achieve soft-switching conditions, the auxiliary circuits including a small inductor and two capacitors are introduced to the bidirectional dc–dc converter. By generating and keeping a recycle current in the auxiliary circuits, the proposed topology can provide soft-switching conditions for both switches of the bidirectional dc–dc converter in fixed frequency control application. Meanwhile, no auxiliary switches are introduced. Due to the existence of the auxiliary circuits, the proposed topology can also reduce the current ripple in the main inductor. Based on this soft-switching method, a family of bidirectional soft-switching dc–dc topologies is derived. These topologies have the similar structures and the same characteristics. The topology deduction, operating principles, and design guidelines are presented in detail. Finally, an experimental prototype is built to verify the analysis and characteristics of the proposed topologies. [ABSTRACT FROM PUBLISHER]

A simple current-feed single-switch forward resonant converter with secondary diode-clamping is proposed for low-power high-density bus converter applications in this paper. The quasi-zero-voltage-switching turn-on and quasi-zero-current-switching (ZCS) turn-off for switch are both achieved. Due to the quasi-ZCS turn-off , the high voltage spike in traditional single forward converter with a reset winding is much reduced. A small diode connected to the output capacitor is utilized to clamp the voltage stress of the switches. The operating principle of the proposed converter is analyzed and a MHz 66 W 24 V-to-12 V prototype with all Si devices is built up. Experimental results show good soft-switching features, and the prototype achieves 95.3% peak efficiency with 270 W/in3 power density. [ABSTRACT FROM PUBLISHER]

In this paper, a new cascaded high step-up multilevel converter topology is designed, which is based on the series connection of several switched-capacitor submultilevel units. The voltage gain of proposed multilevel converter is related to the number of used switches-capacitor units. The main advantage of proposed topology is inherent voltage balancing of used capacitors. The proposed cascade topology is optimized to minimize the number of capacitors, power switches, and the value of voltage on switches for given levels. The proposed topology is compared with other high step-up multilevel converter topologies and conventional structures. The comparison results show that the presented structure requires the least number of switches and dc sources. Moreover, the voltage on the switches of proposed topology is low. In order to confirm the operation of proposed high step-up multilevel converter, both experimental and simulation works are provided. [ABSTRACT FROM PUBLISHER]

Electrolytic capacitors are the components that mainly impact the lifetime of ac/dc light-emitting diode (LED) drivers. Therefore, eliminating electrolytic capacitors from LED drivers is of vital importance. First, the basic derivation concept of a family of flyback-based three-port converters for electrolytic capacitor-less LED drivers is addressed in this paper, by manipulating the power flow among input port, output port, and storage capacitors. Together with the derivation of existing topologies, new topologies are also proposed. After evaluation, an integrated dual flyback converter (IDFC) is chosen, which requires less switching components and simpler control strategy. Following that, the operation principle and switching modes of the IDFC are elaborated, as well as the parameter design and implementation of control strategy. Finally, experiments on a laboratory prototype are carried out to verify the feasibility of the proposed topology. [ABSTRACT FROM PUBLISHER]

This paper proposes two nonisolated single-stage high power factor converters requiring low dc-link capacitance for power LEDs systems. Both converters result from the integration of the power factor correction and the LEDs driver stages, and require a relatively low dc-link capacitance value. A high power factor is demonstrated to be an inherent property of the proposed topologies and no input current control is necessary. The LEDs current is regulated by a symmetrical soft-switching half-bridge converter associated with a capacitive output filter. An accurate mathematical analysis valid for the two converters is detailed, yielding the elaboration of a step-by-step design procedure. In order to verify the analyses carried out, experimental results for two 90 W, 50 kHz, and 220 V converters are also presented. [ABSTRACT FROM PUBLISHER]

Cascaded converters are adopted in many power systems to manage sources and loads at different voltage levels simultaneously. DC bus capacitor is one of the key components in these converters due to its energy storage and fast response capabilities. However, the ripple current through the capacitor will influence its lifetime and the overall efficiency of the converter. Previous studies showed that the capacitor current of ac systems is optimized when the duty cycles are synchronized under in phase or antiphase condition. In this paper, the bus capacitor ripple current of cascaded two-stage converters for dc systems with different combinations of duty cycles is analyzed. It is found that the optimum capacitor current ripple varies depending on the values of individual duty cycles and the phase-shift angle between them. By properly adjusting the phase shift, the capacitor RMS current value can be reduced without affecting the converter normal operation or the need for extra sensing circuits, hence improving the energy conversion efficiency and prolonging the capacitor lifetime with relatively simple implementation. To illustrate, a case study of a two-stage dc/dc converter is carried out. A laboratory prototype converter confirmed a maximum efficiency improvement of 2.8% if the phase shift is adjusted properly when compared to the same converter with the worst case phase-shift angle. [ABSTRACT FROM AUTHOR]

This paper presents a multilevel step-up dc/dc converter for dc-grid-based offshore wind energy conversion applications. The main features of the proposed multilevel converter are as follows: 1) the voltage stress of the power devices can be reduced, making it suitable for high-voltage applications; 2) the boost inductor can be reduced significantly, leading to the outstanding dynamic performance; and 3) high-voltage gain can be obtained and thus is well-suited for high-gain applications. Theoretical analysis was carried out for a four-level step-up converter, based on which, the converter can be extended to any arbitrary number of levels. The proposed four-level converter was verified by a simulation and evaluated by comparing with a conventional multilevel dc/dc converter in terms of the component stress and power device count. The developed topology was implemented on a 2-kW prototype converter to evaluate its feasibility. [ABSTRACT FROM AUTHOR]

This paper presents a new formulation of a finite control set model-predictive control (FCS-MPC) algorithm, allowing to determine the best commutation instant in order to optimize the converter current tracking. This algorithm, mixing properties of FCS-MPC method and time resolution related to pulse width modulation schemes, is illustrated in a parallel flying capacitor converter. The parallel association of classical commutation cells is a good solution for increasing the output current driven by the converters, while the standard semiconductor technology is used. The control strategy used with this type of connection must be able to ensure not only a good distribution of the output current among the different legs, but also the balancing of the floating capacitor voltages. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to present a new structure for switched-capacitor multilevel inverters (SCMLIs) which can generate a great number of voltage levels with optimum number of components for both symmetric and asymmetric values of dc-voltage sources. The proposed topology consists of a new switched-capacitor dc/dc converter (SCC) that has boost ability and can charge capacitors as self-balancing by using the proposed binary asymmetrical algorithm and series–parallel conversion of power supply. The proposed SCC unit is used in new configuration as a submultilevel inverter (SMLI) and then, these proposed SMLIs are cascaded together and create a new cascaded multilevel inverter (MLI) topology that is able to increase the number of output voltage levels remarkably without using any full H-bridge cell and also can pass the reverse current for inductive loads. In this case, two half-bridge modules besides two additional switches are employed in each of SMLI units instead of using a full H-bridge cell that contribute to reduce the number of involved components in the current path, value of blocked voltage, the variety of isolated dc-voltage sources, and as a result, the overall cost by less number of switches in comparison with other presented topologies. The validity of the proposed SCMLI has been carried out by several simulation and experimental results. [ABSTRACT FROM PUBLISHER]

A hybrid switched-capacitor/interleaved boost converter able to provide a high voltage gain and to cancel the input current ripple at a preselected duty cycle was recently presented in the literature. This paper extends that work by proposing an optimized switching strategy for operating conditions at other values of duty cycle. The switching strategy effect on the converter's voltage gain and input current ripple is quantified and compared against the performance under the conventional switching strategy. The approach is validated in the laboratory through hardware prototyping. [ABSTRACT FROM PUBLISHER]

This paper analyzes the interleaved boost with coupled inductors (IBCI) converter, which is an isolated topology that is suitable for high step-up applications. Two main contributions are given: an exhaustive steady-state analysis and an accurate small-signal model. The former allows for deriving a closed-form noniterative design procedure for the power-stage active and passive components. In addition, it reveals an interesting equivalence with an apparently different converter, i.e., the single active bridge. Subsequently, the IBCI converter dynamic behavior is investigated, deriving a nonlinear average model that, under small-signal approximation, can be linearized around a given operating point and used for feedback controller design. A single photovoltaic module interface converter, rated for 300-W output power, is considered as a case study to validate the analysis outcome and the design procedure. Both are fully validated by measurements taken on the laboratory prototype. [ABSTRACT FROM PUBLISHER]

A photovoltaic (PV)-based stand-alone power system is usually used to manage the energy supplied from several power sources such as PV solar arrays and battery and deliver a continuous power to the users in an appropriate form. Traditionally, three different dc/dc converters would have been used. To reduce the cost and improve the power density of the power system, an integrated solution of PV isolated dc/dc three-port converter (TPC) is proposed in this paper. Zero current switching can be achieved for all main diodes and MOSFETs to improve the efficiency, and a continuous input current of solar array is maintained by adding a magnetic switch derived from a fourth winding of the half-bridge transformer. Based on the energy-balancing part formed by boost, the control methods for the single module to realize maximum power point tracking (MPPT), battery charge control, and main bus regulation are proposed. The power system control method for multimodules in parallel is also derived, and the operation of the TPC power system can be transited between conductance mode and MPPT mode automatically. Finally, the experimental results verify that the proposed TPC, together with the proposed control method, meets the requirements of a high-power-density stand-alone PV-battery power system. [ABSTRACT FROM PUBLISHER]

Automotive embedded electronic systems have been increasing in power and complexity and, therefore, more advanced power electronic converters are necessary in these vehicles. Several dual-voltage (42 V/14 V) bidirectional converter architectures have been proposed for automotive systems in recent years. However, most of them have low efficiency or are based in series and parallel configurations with large number of semiconductors and magnetics devices. Therefore, in this paper, we propose a bidirectional high-efficiency converter with lower number of components. This converter was created by merging a switched-capacitor converter and a conventional bidirectional converter, resulting in a hybrid topology. The voltage across the semiconductors of the proposed converter is equal to half of the highest voltage source value. Furthermore, the topology is composed of only one inductor to control the power flow between the two voltage sources. To verify all the mentioned features, a prototype was implemented experimentally, reaching a maximum efficiency of 97.5%. [ABSTRACT FROM PUBLISHER]

In this paper, novel topologies for symmetric, asymmetric, and cascade switched-diode multilevel converter are proposed, which can produce many levels with minimum number of power electronic switches, gate driver circuits, power diodes, and dc voltage sources. The number of required power electronic switches against required voltage levels is a very important factor in designing of multilevel converter, because switches define the reliability, circuit size, cost, installation area, and control complexity. For asymmetric and cascade converter, new algorithms for determination of dc voltage sources values are presented. To produce maximum number of levels at the output voltage, the proposed cascade topology is optimized for different goals, such as the minimization of the number of power electronic switches, gate driver circuits, power diodes, dc voltage sources, and blocking voltage on switches. Comparison of the results of various multilevel converters will be investigated to reflect the merits of the presented topologies. The operations of the proposed multilevel converters have been analyzed with the experimental and simulation results for different topologies. Verification of the analytical results is done using MATLAB simulation. [ABSTRACT FROM PUBLISHER]

This paper presents a single-phase transformerless grid-connected photovoltaic converter based on two cascaded full bridges with different dc-link voltages. The converter can synthesize up to nine voltage levels with a single dc bus, since one of the full bridges is supplied by a flying capacitor. The multilevel output reduces harmonic distortion and electromagnetic interference. A suitable switching strategy is employed to regulate the flying-capacitor voltage, improve the efficiency (most devices switch at the grid frequency), and minimize the common-mode leakage current with the help of a novel dedicated circuit (transient circuit). Simulations and experiments confirm the feasibility and good performance of the proposed converter. [ABSTRACT FROM PUBLISHER]

In this paper, a new fifth-order boost point of load converter is proposed, and then, a digital controller is designed using a Tchebyshev polynomial approach. The proposed converter has a reduced source ripple current together with a better boosting capability at lower duty ratios. Discrete-time models of the converter are formulated and then used in the identification of the direct digital controller stabilizing region. These discrete-time transfer functions are transformed into a Tchebyshev representation, consisting of converter control-to-output and controller transfer functions, which are then used to ascertain the existence of a stabilizing controller, and if stabilization is possible, then the entire set of gains is constructively determined. Using this method, the controller gain range is obtained as a set of inequalities in two variables for a fixed third variable. By sweeping the third variable over its entire range, the complete stabilizing sets are obtained. Within these ranges, the optimal digital controller parameters are obtained through a constrained optimization problem using a genetic algorithm. An integral time absolute error performance index is used in the optimization. A 30-W, 12- to 28-V, and 100-kHz laboratory prototype closed-loop converter has been developed and then tested, both as a simulation and experimentally, for its voltage regulation capability against source and load perturbations. Both the simulated and experimental results confirm the effectiveness of the proposed design. [ABSTRACT FROM PUBLISHER]

This paper unifies the underlying concepts of all basic single-switch, two-state, dc-to-dc voltage-sourced converters, by duality, as generic related current and voltage-sourced converters. By using ac and dc circuit theory, the three basic converters can be transformed to yield all known transfer functions and realizes a proliferation of 33 topologies, three being previously unidentified topologies with unique characteristics. The circuit based systematic unifying approach offers new insight and an alternative interpretation to the origin of the 33 topologies including the Zeta, Cuk, \pmLuo, CSC, Landsman, and Sepic converters. Converter time-domain simulations and corresponding practical results of the three new topologies extol and culminate the concepts and analysis presented. [ABSTRACT FROM PUBLISHER]

A method for extending the duty cycle range of series-input interleaved forward converter (SII-FC) is proposed in this paper. A family of novel SII-FC topologies is derived by integrating two switching legs, which belong to two forward cells, into one switching leg shared by both the two forward cells in the SII-FC. By employing the proposed method, the derived topologies have the advantages of extended duty cycle, reduced components, and conduction losses, which help to achieve high power density and high efficiency. These advantages make the SII-FC topologies suitable for such applications with wide input voltage range. A series-input interleaved two-switch forward converter (SII-TS-FC) is analyzed in detail, which is a typical SII-FC topology developed by the proposed method. It is composed of two low-voltage switching legs and a high-voltage switching leg. Detailed analysis indicates that the maximum duty cycle of the SII-TS-FC can reach 2/3, which is 1.33 times of that of the two-switch forward converter. The switches of the high-voltage leg can be soft-switched when duty cycle is less than 0.5, while the switches of the low-voltage legs can be soft-switched when duty cycle is larger than 0.5. As a result, high efficiency is achieved over a wide voltage range. In addition, the output filter can be reduced due to the interleaving operation of the two forward cells. The operational principles, characteristics, and design considerations for the proposed SII-FC are presented. Experimental results on the SII-TS-FC prototype with 200–400 V input 48 V/12 A output verify the proposed method and analysis. [ABSTRACT FROM PUBLISHER]

This paper presents the hybrid seven-level cascaded active neutral-point-clamped (ANPC)-based multilevel converter. The converter topology is the cascaded connection of a three-level ANPC converter and an H-bridge per phase. The voltage of the H-bridge is actively maintained to the required level through selection of the switching states of the converter. The topology is operated under selective harmonic elimination pulsewidth modulation (SHE-PWM), maintaining the switching frequency of the converter to a minimum. The operating principles, voltage balancing methods, and limitations of the converter are analyzed together with extensive simulation results of the topology. Experimental results from a low-power laboratory prototype are presented that verify the operation of the hybrid converter under SHE-PWM. [ABSTRACT FROM PUBLISHER]

A new scheme for nine-level voltage space-vector generation for medium-voltage induction motor (IM) drives with open-end stator winding is presented in this paper. The proposed nine-level power converter topology consists of two conventional three-phase two-level voltage source inverters powered by isolated dc sources and six floating-capacitor-connected H-bridges. The H-bridge capacitor voltages are effectively maintained at the required asymmetrical levels by employing a space vector modulation (SVPWM) based control strategy. An interesting feature of this topology is its ability to function in five- or three-level mode, in the entire modulation range, at full-power rating, in the event of any failure in the H -bridges. This feature significantly improves the reliability of the proposed drive system. Each leg of the three-phase two-level inverters used in this topology switches only for a half cycle of the reference voltage waveform. Hence, the effective switching frequency is reduced by half, resulting in switching loss reduction in high-voltage devices. The transient as well as the steady-state performance of the proposed nine-level inverter-fed IM drive system is experimentally verified in the entire modulation range including the overmodulation region. [ABSTRACT FROM PUBLISHER]

This paper is devoted to the step-up dc/dc converter family with a cascaded quasi-Z-source network (qZS-network). The cascaded (two-stage) qZS-network could be derived by the adding of one diode, one inductor, and two capacitors to the traditional quasi-Z-source inverter (qZSI). The proposed cascaded qZSI inherits all the advantages of the traditional solution (voltage boost and buck functions in a single stage, continuous input current, and improved reliability). Moreover, as compared to the conventional qZSI, the proposed solution reduces the shoot-through duty cycle by over 30% at the same voltage boost factor. Theoretical analysis of the two-stage qZSI in the shoot-through and non-shoot-through operating modes is described. The proposed and traditional qZS-networks are compared. A prototype of a step-up dc/dc converter with the cascaded qZS-network was built to verify the theoretical assumptions. The experimental results are presented and analyzed. Finally, a further optimization method of the cascaded qZS-network is proposed, and some practical design issues are discussed. [ABSTRACT FROM PUBLISHER]

In this paper, a new topology for cascaded multilevel converter based on submultilevel converter units and full-bridge converters is proposed. The proposed topology significantly reduces the number of dc voltage sources, switches, IGBTs, and power diodes as the number of output voltage levels increases. Also, an algorithm to determine dc voltage sources magnitudes is proposed. To synthesize maximum levels at the output voltage, the proposed topology is optimized for various objectives, such as the minimization of the number of switches, gate driver circuits and capacitors, and blocking voltage on switches. The analytical analyses of the power losses of the proposed converter are also presented. The operation and performance of the proposed multilevel converter have been evaluated with the experimental results of a single-phase 125-level prototype converter. [ABSTRACT FROM PUBLISHER]