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In recent years, very high frequency (VHF) converter has attracted much attention. However, with rich parasitic parameters and complex resonance links, there are some great difficulties to the modeling of such systems. Taking the on-off controlled VHF resonant boost converter as an example, this paper presents an accurate modeling and analysis method that considers multiple parasitic parameters. First, the closed-loop VHF converter system is divided into a main network and a parasitic oscillation network. Then, based on the operation analysis, an equivalent circuit model characterized by a time-varying input voltage source and two variable duty-cycle controlled switches is proposed. It worth noting that both the time-varying input and the controlled switches take into account the influences of the parameters. Furthermore, the periodic approximate analytical solution of the output voltage in the on stage is obtained by using the equivalent small parameter method to the proposed circuit model. And then combining the solution of the parasitic oscillation network and on-off state switching conditions, the steady-state waveform of output voltage can be obtained quickly. Finally, a prototype with operating frequency of 21.44 MHz is built to verify the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

The main standard for avionic equipment DO-160G defines a set of tests that require compliance before the employment of a device in aircraft. An important test involves the generator voltage and consequential current distortion of the three-phase load in the variable 360–800 Hz frequency grid. The main purpose of this paper is to present and analyze a systematic design methodology for three-phase boost and buck rectifiers in order to meet with the voltage distortion test requirement. For a given voltage harmonic profile, the current harmonic limits that have to be satisfied are translated into equivalent per-harmonic admittances and a profile of maximum rectifier input admittance versus frequency is obtained. The defined profile, due to normalization, is applicable to arbitrary power level with simple shifting by the base admittance governed by the converter nominal power. It is shown that for boost-type rectifiers there is a tradeoff between current controller bandwidth and input inductor size, while for the buck-type rectifiers main limitation lies in the input LC filter design used for differential electromagnetic interference filtering. The experimental results conducted on an SiC three-phase 10 kW VIENNA rectifier are tightly backing up the proposed theoretical analysis. This paper is accompanied by three videos demonstrating experimental measurement of d-axis open-loop duty cycle to inductor current transfer function, loop-gain of d-axis current controller with 3.8 kHz bandwidth and variable grid frequency 360–800 Hz operation of the converter under 0% and 10% input three-phase voltage total harmonic distortion. [ABSTRACT FROM AUTHOR]

Various methods have been presented in the past to emulate the electrical behavior of modular multilevel converters (MMCs). To meet the demands for the reliability aspect study of MMCs, this paper proposes a viable setup to emulate the thermal behavior and to investigate its feasibility for reliability testing and thermal model validation of the power modules in the MMC. The proposed mission profile emulator has three distinctive features: 1) capable of emulating and measuring the thermal stresses of power modules; 2) capable of implementing practical switching profile as a full-scale MMC; and 3) having significantly reduced requirement for dc power supply compared to existing setups used for electrical studies. Theoretical discussions, and simulations as well as the experimental results are presented to demonstrate the capability of the mission profile emulator both electrically and thermally. Moreover, this paper is accompanied by a video demonstrating how to measure the junction temperature of the power devices using the optical fiber and the thermal camera. [ABSTRACT FROM AUTHOR]

With the increasing demand for flat displays, slim telecom/IT power supplies, and portable devices, the use of planar transformers (PTs) is becoming mandatory to achieve slim, compact converter designs. In particular, PTs present a significant opportunity to replace tall and bulky wire-wound transformers in industry standard LLC converters. However, the common-mode (CM) noise generated by PTs remains a significant obstacle to make LLCs effective. The CM noise issues are originated by large capacitances in overlapping primary and secondary layers of PTs, leading to serious electromagnetic interference issues. This paper develops a new winding method to overcome CM noise in LLC PTs. By minimizing noise, the proposed method prevents the use of bulky CM chokes, helping to keep a slim/flat form factor for LLC converters with high-power density. As well, the proposed winding method maintains low ac resistance and leakage inductance, two desirable features in high-efficiency transformers. The paper explains the root cause of CM noise in LLC PTs and develops a comprehensive method that targets all sources of CM noise in the transformer and is applicable to any type of PTs. The proposed winding method successfully shields problematic turns with high $dv/dt$ and overlaps the turns with the same $dv/dt$. As a result, circulating currents between primary and secondary (which are known as CM noise) are prevented, which leads to significant reduction of the converter's noise. Experimental results show that the proposed PT generates 11–20 dBμV less CM noise than a traditional PT with the same parasitic capacitance, which is the result of using the proposed winding method. [ABSTRACT FROM AUTHOR]

Analytical expressions that have been derived to calculate ac resistance and losses of magnetic devices at high frequencies have primarily used a one-dimensional approximation, and have used Cartesian coordinates or approximations that are equivalent to Cartesian coordinates. The result is Dowell's equation. This paper examines the effect of winding curvature on the losses relative to Dowell's equation by solving the problem completely in cylindrical coordinates. The error in Dowell's equation relative to a full cylindrical solution is found to be as great as 33% for some designs. A mathematical model is derived for the relative error between the two solutions, which can be used to assess the accuracy of Dowell's equation for a particular design, as well as a correction factor for Dowell's equation. The corrected Dowell's equation using the model is validated using finite-element analysis simulations as well as previously published experimental data. This paper is accompanied by Python codes to generate all data and figures used in the paper, a Python object that implements the derived mathematical model, and Lua scripts to run the finite-element simulations using FEMM. [ABSTRACT FROM AUTHOR]

In this paper, a new dc–dc high voltage gain converter with low-voltage stresses on switches and diodes is proposed. Even though, in the topology of the proposed converter there are not any coupled inductors and transformer utilized, the voltage conversion ratio of the proposed converter is considerable in comparison to its conventional types. Also, two switches of the proposed converter provide longer charge time for two inductors which make the proposed converter capable of providing high voltage gain without preselecting extremely large duty cycles. In addition, the number of power circuit components of the proposed structure are few and the voltage stresses on semiconductor elements are low. In this paper, theoretical analysis of the proposed converter for each operating mode is presented and the voltage gain, voltage and average current stresses of elements, maximum input current ripple, efficiency and equations of critical inductances are calculated. Moreover, to verify the capability of the proposed converter, it is comprehensively compared with other similar recently presented high voltage gain boost converters. Finally, an approximately 12 V/380 V and 520-W prototype of the proposed converter is implemented in laboratory to demonstrate its practical performance, then, the experimental results reconfirm each other and theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper presents bidirectional grid-connected modular multilevel converters (MMC) with direct digital control and division-summation processes to achieve power-injection and rectification functions. A direct digital control is developed to track current references, regulate dc-bus voltage and cell voltage, and balance the upper and lower dc-bus voltages. It can accommodate wide filter-inductance variation and take care of source voltage harmonics to achieve tight current tracking and low distortion output current. Based on the power-balance principle, the commands of arm currents can be determined directly. In this paper, the MMC configuration is introduced first, and then the control laws for current tracking and voltage regulation are derived in detail. Experimental and simulated results obtained from two 50 kW MMCs operated in power-injection and rectification modes have verified the analysis and discussion. [ABSTRACT FROM AUTHOR]

This paper presents an adaptive multi-loop control scheme for inverters interlinking dc voltage sources to single-phase, low-voltage ac grids. Control self-adaptation is particularly useful in the case of weak grids that, due to frequent physical modifications (e.g., network reconfigurations and disconnection of generators/loads) and intrinsic lack of inertia, present strongly time-variant characteristics. The solution presented in this paper is based on a high-performance converter controller with auto-tuning capabilities. It is shown that the applied auto-tuning method can significantly widen the stability region of the interlinking converter, covering a broad range of grid impedance values. In addition, within the stable region, the controller maintains the nominal performance. Experimental results are reported validating the proposed approach in realistic operating conditions, including grid voltage distortion and variations of amplitude and frequency. [ABSTRACT FROM AUTHOR]

This paper introduces a novel modeling approach that allows to obtain fast simulations of pulsewidth-modulated dc–dc switched-mode power supplies (SMPS). The proposed methodology combines the use of precise switched models during transient evolutions and averaged models during steady-state or slowly varying conditions. In that way, the resulting mixed modeling approach enables to obtain the detailed switching behavior of SMPS in the context of long-term simulations. The commutation between models is automatically performed in runtime by an algorithm that detects the transient or slowly varying condition according to the evolution of some model variables. When the precise switched model is used, the mentioned algorithm also adjusts the averaged model parameters so that its results are accurate irrespective of the operating point. This paper also describes the implementation of the methodology in the Modelica language and reports simulation experiments showing that the results are as accurate as those obtained using precise switched models, but several times faster. [ABSTRACT FROM AUTHOR]

This paper presents an interleaved boost converter with a bifold Dickson voltage multiplier suitable for interfacing low-voltage renewable energy sources to high-voltage distribution buses and other applications that require a high-voltage-gain conversion ratio. The proposed converter was constructed from two stages: an interleaved boost stage, which contains two inductors operated by two low-side active switches, and a voltage multiplier cell (VMC) stage, which mainly consists of diodes and capacitors to increase the overall voltage gain. The proposed converter offers a high-voltage-gain ratio with low voltage stress on the semiconductor switches as well as the passive components. This allows the selection of efficient and compact components. Moreover, the required inductance that ensures operation in the continuous conduction mode (CCM) is lower than the one in the conventional interleaved boost converter. The distinction of the proposed converter is that the inductors’ currents are equal, regardless of the number of VMCs. Equal sharing of interleaved boost-stage currents reduces the conduction loss in the active switches as well as the inductors and thus improves the overall efficiency, as the conduction power loss is a quadratic function. In this paper, the theory of operation and steady-state analysis of the proposed converter are illustrated and verified by simulation results. A $\text{200-W}$ hardware prototype was implemented to convert a $\text{20-V}$ input source to a $\text{400-V}$ dc load and validate both the theory and the simulation. [ABSTRACT FROM AUTHOR]

In a dual active bridge (DAB) dc–dc converter, modulating the phase-shift ratios can suppress reactive power and increase the efficiency under non-unity voltage gain conditions. Derivation of the optimal phase-shift ratios to achieve the minimum reactive power is challenging because a DAB can operate in four different scenarios (forward/backward, buck/boost) and each scenario has five operating modes. This paper first introduces a transformation in which different DAB operating scenarios (forward/backward, buck/boost) can be equivalent to one another; then optimization of only one scenario (forward/buck) is required. Next, for the five modes in forward/buck scenario, based on a graphical method, this paper proves that each operating point of Modes 1, 2, and 5 can be mapped into that of Mode 3 with lower conduction losses, and only two modes require detailed analysis. The optimization process of these two modes are derived step-by-step. Global optimal phase-shift signals that minimize the reactive power under four different DAB operating scenarios (forward/backward, buck/boost) are presented. A simple table and control block diagram are presented for practical implementation of global reactive-power minimization control. Experimental comparison with other modulation schemes verifies the efficiency improvement of the proposed control method. [ABSTRACT FROM AUTHOR]

This paper proposes a new class of topologies of single-stage high-frequency ac-link power converters, which is capable of providing both voltage step up/down within a wide frequency and voltage ranges. The proposed family, which supports bidirectional power flow, can interface various single/multi-port dc and/or single/multi-phase ac systems to provide dc–dc, dc–ac, ac–dc, or ac–ac power conversion. In this family of converter, which offers a very modular structure, a small inductor that forms the link exchanges power entirely or partially between the source and load. The proposed family can function in buck, boost, and/or buck–boost modes of operation, and a combination of these modes of operation is also feasible. In comparison to the parallel inductive four-quadrant link converters, the proposed family features a significantly reduced link peak current, reduced switch ratings, and reduced total number of power switches. These features enhance the efficiency, reduce the total cost, and increase the power density of the system. In order to further improve the overall efficiency of the system, minimize the current/voltage stress over all utilized semiconductor devices, and lower electromagnetic interference (EMI), a small capacitor is placed in parallel with the link inductor to realize soft-switching operation for the proposed configurations. Moreover, the proposed converters have the potential to incorporate a lightweight single-phase high-frequency transformer for electrical isolation. The proposed circuit topologies prevent reverse recovery issues and eliminate losses corresponding to body diodes of power switching devices via utilizing power switches in conjunction with external fast recovery diodes. The proposed family offers a very high level of reliability owing to its immunity from short circuit of input and output terminals and open circuit of the link inductor, which may occur in other power converters due to commutation problem resulting from a short deadtime or an overlap time between switches, unwanted control command, delay in electronic circuits, or EMI noise's misgating on or off, in addition to the absence of electrolytic capacitors in the power circuit. A control approach is also developed to regulate input and output currents in one stage of power conversion. A detailed theoretical analysis, operation, design methodology, and control strategy of the proposed family are provided in this paper, and the effectiveness and performance of the proposed converter family are verified via simulation results and experimentally. [ABSTRACT FROM AUTHOR]

In this paper, a current controller for a parallel operation of inverters is described. When inverters operate in parallel, it is a well-known fact that the inverter current is composed of the average current (AVC) and the zero-sequence circulating current (henceforth ZSCC), which inevitably flows between inverters under the parallel operation. Considering this, previous studies concentrated on reducing ZSCC. However, in this paper, it is found that the inverter current has another component, a differential current, in addition to the two components of AVC and ZSCC. Based on these three decomposed current components, three equivalent circuits are derived from n-paralleled inverters. To minimize the differential current and improve the regulation performance of the total output phase current, a decomposed current control scheme is proposed from equivalent circuit models. The proposed algorithm is applied to a system consisting of three paralleled two-level inverters with small shared inductance whose dc links are connected in common. Additionally, synchronous pulsewidth modulation is employed as the PWM method for each inverter. The proposed current controller is compared with two conventional current controllers, one where each inverter controls its own currents and the other where only AVC is controlled. Through experiments, it is shown that these conventional controllers have limitations and the proposed current controller overcomes these limitations. The effectiveness and feasibility of the proposed control scheme are verified through experimental results. Especially, both theoretical analysis and experiment results verify that the proposed method is robust with regard to parameter errors. [ABSTRACT FROM AUTHOR]

Switching behavior analysis is an indispensable step for evaluating the steady-state performance of a bidirectional dc–dc converter and a prerequisite for soft-switching modulation design. For dual-bridge series resonant dc–dc converters (DBSRCs), the commonly used fundamental harmonic approximation (FHA) does not usually provide predictions accurate enough for reliable analysis and design. This paper discloses the exact closed-form solution for the zero-voltage switching (ZVS) operation conditions of DBSRCs for the most general case, in which all modulation quantities—i.e., phase shift, duty cycles, and switching frequency—are included. The proposed approach relies on a geometrical analysis of the converter state-plane trajectory, and allows us to analytically predict the ZVS or hard-switching state of any switch and for any given converter operating point. By inherently capturing the effects of all tank harmonics, the model disclosed in this paper shows higher accuracy than the conventional FHA-based approach, and translates into a practical tool for ZVS prediction and optimization at the converter design stage. Based on the derived analytical results, switching behavior of DBSRCs with minimum rms current trajectory (MCT) modulation is investigated, and an effective design choice of resonant-to-switching frequency ratio is presented, which contributes to reduced switching losses and enhanced efficiency. Furthermore, a variable frequency modulation scheme is formulated, achieving ZVS operation of all transistors over a wide input/output voltage range and efficiency improvement versus MCT technique. The analysis and conclusions are validated via extensive experimental tests on a 700 W DBSRC prototype. [ABSTRACT FROM AUTHOR]

In this paper, a novel high-conversion-ratio isolated bidirectional dc–dc converter for distributed energy storage systems is proposed. In the buck mode, the proposed converter is equivalent to that of a cascade consisting of an isolated buck–boost converter and a buck converter, thus achieving a high step-down ratio. Likewise, in the boost mode, the converter is equivalent to the cascaded structure consisting of a boost converter and an isolated buck–boost converter, and then, a high step-up ratio is achieved. Therefore, the proposed topology exhibits a high conversion ratio with low transformer turns ratio, improving the efficiency of high-frequency transformers and the integration and reliability of the control system. In addition, voltage spikes caused by the leakage inductance can be avoided as the leakage inductance energy is released to capacitors in a high-voltage side or a low-voltage side. Moreover, a zero-voltage-switching (ZVS) operation reduces switching losses and improves the conversion efficiency. The operating principles and theoretical derivations of the proposed converter along with ZVS implementations are discussed in detail in this paper. Furthermore, the validity and performance of the proposed converter are verified using a prototype with 600-V high voltage, 48-V low voltage, and 2-kW output power. [ABSTRACT FROM AUTHOR]

In this paper, a new class of bidirectional partial-resonance power converters is presented. The proposed family can be configured to interface single- or multi-port dc, single- or multi-phase ac systems at input-side and/or output-side. The proposed family offers a very modular structure, which can lead to cost reduction from a common designed module. In this converter, which accomplishes power conversion in a single stage, a small inductor placed in series with the input and output switch-bridges forms the link. This small link inductor is responsible for transferring power between different ports of the system. The proposed topologies can operate in buck, boost, and buck–boost modes of operation to step up and/or step down the voltage. In buck–boost mode of operation, the converter is controlled such that the power is entirely transferred through the link inductor; whereas, in buck or boost modes of operation only a fraction of the power is transferred through the link inductor, and the remaining power is directly transferred from input phases to the output phases. Galvanic isolation, which is typically a prominent factor contributing to power density of a converter, can be provided by means of a compact and lightweight single-phase high-frequency transformer added to the link. In comparison with earlier generations of partial-resonance inductive-link power converters, in the proposed converter, the level of link peak current and consequently power-loss, as well as voltage and current stress of switches are dramatically decreased. A very small film capacitor can be placed in parallel with the link inductor to facilitate zero-voltage-switching (ZVS) operation for all the switches/diodes. Apart from increasing the overall efficiency, minimized dv/dt stress and improvement in power density are achieved by adding the link capacitor. The proposed converter employs four-quadrant switches, i.e., bidirectional-conducting bidirectional-blocking switches, and charges the link inductor in both positive and negative directions in each cycle. In view of this, better utilization of the link inductor and lower total harmonic distortion (THD) are offered. Furthermore, two distinct switching algorithms are developed for the proposed family of converters. In this paper, the detailed behavior of the proposed family is investigated analytically, and simulation and experimental results are presented to evaluate the performance and effectiveness of the proposed converter. A low-power proof-of-concept prototype with input voltage of 59 V/161 V, load voltage of 178 V/73.5 V, maximum switching frequency of 4.9 kHz/3.65 kHz at 215 W/450 W in a step-up/step-down operation is considered for the experimental verification. [ABSTRACT FROM AUTHOR]

In this paper, a new non-isolated two-input single-output dc–dc converter with high voltage gain is proposed. In the proposed converter, there are two three-winding coupled inductors used to achieve a high voltage gain and ripple-free input currents. The proposed converter has two switches, and their control pulses are the same as the control pulses of the two-phase interleaved converters with a phase shift equal to $\text{180}^{\circ} $. The voltage stresses of switches and diodes are reduced and are always lower than the high output voltage. The proposed converter is extendable to a four-input single-output converter in which the switches have the control pulses the same as those in four-phase converters with phase shifts equal to $\text{90}^{\circ} $. In this paper, the proposed topology is analyzed in all operating modes, and the values of current and voltage stresses of all switches and diodes, voltage gain, and required conditions for input current ripple cancelation are calculated during a switching period. Finally, the accuracy performance of the proposed converter is reconfirmed through experimental results for 225- and 298-W prototypes. [ABSTRACT FROM AUTHOR]

This paper studies the high power density bidirectional dc–dc converter with interleaving, soft-switching, and near critical conduction mode (near-CRM) operation. Systematic design and control methods are proposed to enhance the effectiveness of passive currents balancing between multiple interleaved phases without using individual phase current feedbacks. This paper first analyzes the zero voltage turn-on operation, including the turn-off energy diversion by the added snubber capacitor and the turn-off resonance models. Second, the intrinsic inverse co-relation between the phase current deviation and the resulting effective duty cycles variation is quantitatively formulated and modeled as a closed-loop mechanism that balances the currents passively. Then, the design constraints of the system parameters including the snubber capacitance, dead time, and valley currents of the near-CRM mode are formulated to guarantee the effectiveness of counteracting the current unbalance. Finally, a variable switching frequency control is proposed to actively control the valley current and maintain the current balancing effectiveness throughout the operating range. An IGBT-based 20-kW three-phase interleaved prototype with the maximum efficiency of 99.1% is constructed to verify the proposed design and control methods. [ABSTRACT FROM AUTHOR]

This paper proposes a novel active-clamp forward converter (ACFC) with a lossless-snubber on the secondary-side, which combines a resonant capacitor and a clamping diode with an output inductor in parallel. The conventional ACFC achieves zero-voltage-switching on switches of the primary-side during dead time for reducing the switching loss and voltage spike. Unfortunately, on the secondary-side of transformer, the voltage spike damages the free-wheeling diode and rectifier diode due to the reverse recovery current and junction-capacitor of the diode and leakage inductance of the transformer. This paper proposes a lossless-snubber on the secondary-side operation for reducing the voltage spike on the free-wheeling diode and forward-rectifier diode. Therefore, the converter proposed in this paper is suitable for high-output-current applications. Experimental results are shown to verify the analysis and design procedure of the proposed forward converter. [ABSTRACT FROM AUTHOR]

This article develops a series of improved Z-source dc–dc converters to realize additional voltage pumping and high power density through two propositions. Proposition 1 develops two improved positive- and negative-connected Z-source dc–dc converters (IPZSC and INZSC), using the same number of components as in the existing voltage pumping Z-source converter. Based on Proposition 1, Proposition 2 proposes four novel embedded Z-source dc–dc converters (EZSCs) by placing the source in a specifically designed position, which realizes lower voltage stresses across capacitors. Various technical aspects of the proposed EZSCs, including operations, power losses, and small signal stability analyses are detailed in this paper. Besides, comparisons between the proposed series of improved Z-source dc–dc converters and other existing Z-source dc–dc converters are thoroughly made to demonstrate the better performance of the EZSCs. Finally, experiments are conducted to well validate the effectiveness and superiority of the proposed converter circuits. [ABSTRACT FROM AUTHOR]

The instantaneous output power of the two-stage single-phase grid-connected photovoltaic (PV) inverter pulsates at twice the line frequency ($2f_{{\text{o}}}$), generating second harmonic current (SHC) in the front-end dc–dc converter and PV panel, which will affect the maximum power point tracking operation and deteriorate the overall conversion efficiency. The generating mechanism of the SHC is analyzed in this paper and it is pointed that in order to eliminate the SHC in the front-end dc–dc converter and PV panel, the voltage loop gain of the front-end dc–dc converter should be high enough at $2f_{{\text{o}}}$. Since there is a −180° phase abrupt at the resonant frequency of the input side filter capacitor and the inductor, the system may be unstable. To cope with this problem, the inductor current feedback active-damping scheme (ADS) is adopted. For further improving the loop gain at $2f_{{\text{o}}}$ , proportional–integral–resonant regulator with ADS (PIR + ADS) is proposed in this paper. Besides, a step-by-step closed-loop parameters design method is presented. Finally, a 3-kW two-stage single-phase grid-connected PV inverter has been fabricated and tested, and the experimental results verify the feasibility of the proposed control schemes. [ABSTRACT FROM AUTHOR]

This paper presents two high-voltage direct-current circuit breakers that have the capability of interrupting a short-circuit current within several milliseconds. They consist of a current-limit inductor, a current-control inductor, one or two mechanical switches, and a multilevel converter with phase-shifted-carrier pulsewidth modulation. The two breakers can commutate an almost zero current from the main branch to the auxiliary branch. This paper proposes an original breaker with low-voltage and high-voltage mechanical switches connected in series, followed by a simplified breaker with a single high-voltage mechanical switch. Finally, this paper includes experimental verification by two slightly different downscaled breakers rated at 300 Vdc and 150 Adc, as well as confirmation of an actual original breaker by circuit simulation using the “PSCAD/EMTDC” software package. [ABSTRACT FROM AUTHOR]

Inductor current is an important feedback parameter in synchronous buck converters (SBCs). It is used for overcurrent protection, current sharing among interleaved modules, and current-mode feedback regulation, among others. While implementing a digital controller, inductor current is sensed and fed into the controller through a high sampling frequency analog to digital converter (ADC). As the switching frequency of the converter becomes higher, the need for an even higher sampling frequency ADC also goes up, which is a distinct disadvantage in terms of the overall cost. This paper discusses a simple current estimation technique that avoids use of any expensive current sensor and high sampling frequency ADCs. The paper shows that in a buck converter, inductor current can be estimated by tracking the width of the switch node voltage. Implementation and limitations of the proposed current estimation scheme are discussed in detail. The proposed method is validated using a 3.3 V–15 A SBC prototype and results show the estimation technique is accurate within 5% with a converter switching frequency of 800 kHz. In order to prove the effectiveness of the technique in feedback regulation, the current estimation technique is used to implement average current mode and hysteretic current mode control on a SBC. To prove the effectiveness of the proposed current estimation scheme, it is used in closed-loop control of the SBC to verify the dynamic responses, such as start-up transient, step change in load, and reference. [ABSTRACT FROM AUTHOR]

Light-emitting diodes (LEDs) are solid-state devices with specific $v$ – $i$ characteristics. In this paper, we study the basic requirement of the driving circuits and discuss the proper approach to drive LEDs in view of their characteristics. We compare voltage source driving and current source driving, and discuss their relative advantages and constraints. We specifically introduce the use of circuit duality principle for developing new current-source-mode (CSM) drivers that are less known but are theoretically more versatile compared to their conventional voltage-source-mode counterparts. The study highlights the effects of the choice of driving circuits in terms of the number and size of circuit components used, duty cycle variation, sensitivity of control, nonlinearity and control complexity of LED drivers. We propose a CSM single-inductor multiple-output (SIMO) converter, which demonstrates the advantage of having inductorless and easily controlled current-source drivers, and present a comparison of the CSM SIMO converter with the existing SIMO converters. We further illustrate that a high-voltage-step-down ratio can be naturally achieved by the CSM high-voltage-step-down converter without the use of transformers. This paper presents a systematic and comparative exposition of the circuit theory of driving LEDs, with experimental evidence supporting the major conclusions. [ABSTRACT FROM AUTHOR]

This paper presents a new digital control scheme for active virtual ground-bridgeless PFC (AVG-BPFC), which is able to obtain an optimized solution between the system efficiency and electromagnetic interference performance in the PFC stage. However, a resonant characteristic is generated from the input LCL filter structure of the converter. In addition, there is a phase difference between two inductor currents which also leads the controller design in the AVG-BPFC to become challenging, especially on the system stability and current quality. Thus, a triple loop control's architecture together with an integrated state machine is proposed as the control methodology of the AVG-BPFC. Under the simple control structure in the digital platform, a stable system is achieved together with a precise grid current tracking function. Such control scheme was implemented digitally on a 1.5 kW prototype. In this paper, theoretical models of the whole system were analyzed and the system performance was successfully verified in both steady state and transient state conditions. The experimental results show a good agreement with the theoretical knowledge. [ABSTRACT FROM AUTHOR]

This paper discusses an alternative to reduce harmonic current distortion in a 12-pulse rectifier. The circuit is based on a generalized autotransformer connection with low power-to-core that feeds two isolated SEPIC converters. Compared to other passive devices operating as conventional 12-pulse rectifiers, besides a tight dc bus, the use of static converters can, by means of an active current imposition, provide very low harmonic distortion of current. This paper presents a theoretical analysis which is corroborated by computational and experimental results. The results show that the performance of the proposed converter is similar to the performance provided by three-phase unity power factor PWM rectifiers, however, only two active switches are deployed. [ABSTRACT FROM AUTHOR]

Recent studies have proved that sustainable saturation operation of Ferrite Power Inductors (FPIs) allows reducing the inductor size and increasing the power density in Switch-Mode Power Supply (SMPS) applications. This paper discusses a new behavioral model for reliable prediction of ac power loss in FPIs, including the effects of saturation. The new model has been identified by means of the Genetic Programming (GP) algorithm combined with a Multi-Objective Optimization (MOO) technique, starting from large sets of power loss experimental measurements. The proposed ac power loss model uses as input variables the voltage and switching frequency imposed to the inductor by the SMPS operation, while the dc inductor current is used as a parameter expressing the impact of saturation. Such quantities can be easily determined for whatever converter topology and in real-world switching operation, thus confirming the readiness and the easiness-to-use of the proposed behavioral model. The results of experimental tests presented in this paper prove the reliability of the power loss predictions, also by correctly accounting for the impact of inductors saturation. [ABSTRACT FROM AUTHOR]

The influence of a filter inductor on the steady-state performance of a parallel-type resonant converter is elaborated and analyzed in this paper. By steady-state operation analysis, it is shown that the ripple current of the filter inductor results in an inaccurate prediction of fundamental harmonic approximation (FHA), and such problem would become serious when the filter inductance is small. In order to portray such feature, an improved fundamental harmonic approximation (IFHA) is proposed. Unlike an FHA equivalent circuit, an equivalent inductor is added to the ac resistance parallelly in an IFHA equivalent circuit. Due to that, the equivalent inductor branch takes account of the ripple current of the filter inductor, and the IFHA is expected to own higher accuracy and can be used in a parameter design procedure. In this paper, the equivalent inductor expressions of full-bridge rectifier and current-doubler rectifier are derived as examples. In order to verify the theoretical analysis, a 500 W LCC resonant converter is built as a prototype. The close-loop experiment results show that small filter inductance would lead to the failure of output voltage regulation and hard-switching operation of power switches. And open-loop experiment results show the IFHA gives more accurate predictions than those of FHA. [ABSTRACT FROM AUTHOR]

This paper proposes a high-power-density and reliable inverter topology, which transfers the maximum power of a PV array to the load in one power conversion stage. The single-stage power conversion, along with the soft-switching capability of the proposed three-phase PV inverter promises high efficiency at all operating points. Instead of a capacitive dc link that decouples the dc–dc converter and the voltage source inverter in traditional two-stage PV inverters, a high-frequency capacitive ac link is employed in the proposed inverter, which enables exploiting a very small film capacitor, rather than a bulky electrolytic capacitor, for transferring power. Eliminating electrolytic capacitors prolongs the lifetime of this inverter. Considering the long lifetime of PV modules, this feature is of high importance in PV applications. The high-frequency ac link also allows using high-frequency transformers for providing galvanic isolation. Therefore, this inverter is expected to have a very high power density. This paper presents principles of the operation and control, design, and analysis of this inverter, and verifies the performance of the inverter through two prototypes: a 2-kW Si-based prototype and a 2-kW SiC-based prototype operating at different switching frequencies. [ABSTRACT FROM AUTHOR]

In data center and telecommunication power supplies, the front-end dc–dc stage is required to operate with a wide input voltage range to provide hold-up time when ac input fails. Conventional LLC converter serving as the dc–dc stage is not suitable for this requirement, as the normal operation efficiency (at 400 V input) will be penalized once the converter is designed to achieve high peak gain (wide input voltage range). This paper examined the operation of the LCLC converter and revealed that the LCLC converter could be essentially equivalent to a set of LLC converters with different magnetizing inductors that are automatically adjusted for different input voltages. In nominal 400 V input operation, the LCLC converter behaves like an LLC converter with large magnetizing inductor, thus the resonant current is small. In the hold-up period, when the input voltage reduces, the equivalent magnetizing inductor will reduce together with switching frequency reducing, thus the converter achieves high peak gain. In this paper, a new design methodology is also proposed to achieve optimal utilization of the two resonant capacitors for high power application. To verify the effectiveness of the LCLC converter for hold-up operation, comprehensive analysis has been conducted; a detailed step by step design example based on capacitor voltage stress is introduced; an experimental LCLC prototype optimized at 400 V, with input voltage range of 250–400 V and 12 V/500 W as output has been presented. [ABSTRACT FROM AUTHOR]

A single-stage three-phase ac–ac converter benefiting from a high-frequency alternating link voltage is proposed in this paper. In this converter, a very small film capacitor can transfer the energy from the input to the output, owing to the high-frequency alternating voltage of the link. This eliminates the need for large electrolytic capacitors that are typically used in dc-link ac–ac converters. Moreover, a compact high-frequency transformer at the link can replace the bulky low-frequency transformers, in case isolation is required. These features increase the power density as well as reliability of the proposed converter in comparison with the conventional dc-link converters. The number of required switches in the proposed converter is 12, which is less than the number of switches needed in matrix converters, leading to lower switching and conduction losses. Despite being single-stage, the proposed ac–ac converter is capable of both stepping up and stepping down the voltage and also frequency transformation. This eliminates the need for using cascaded power converters. In this paper, the operation principles of the proposed ac–ac converter are investigated, and variable switching frequency and fixed switching frequency control methods for operating this converter are introduced. The performance of the converter is verified through simulation and experiment. [ABSTRACT FROM AUTHOR]

In this paper, a new structure for a nonisolated boost dc–dc converter is proposed. The proposed converter generates higher voltage gain than some conventional nonisolated boost dc–dc converters. In this paper, the voltage and current equations of the elements and voltage gain in continuous conduction mode and discontinuous conduction mode are extracted. Then, the critical inductance converter is extracted and the current stresses in the switches are calculated. To achieve high voltage gain, a generalized structure based on the proposed structure generates for dc–dc converters. Meanwhile, the root mean square current relations of devices are obtained for an extended structure. Finally, the results of PSCAD/EMTDC software and laboratory prototype are used to reconfirm theoretical concept. [ABSTRACT FROM AUTHOR]

In the paper by Patra et al., a single-inductor multiple-output switcher was presented to produce buck, boost, and inverted outputs simultaneously. Unfortunately, this study showed some unexpected mistakes, especially in state-space equations and in the calculation of output voltages. The objective of this note was to provide correct analysis and rectify the errors in this paper. Some tables and equations have been modified that were present in the initial draft of this paper. The obtained parameters in this work could be an effective supplement and extension for the original work in the paper by Patra et al. [ABSTRACT FROM AUTHOR]

Soft magnetic powder cores with their high saturation flux density and low core loss are excellent alternatives for filter inductors in inverter-based applications. However, their nonlinear current-dependent inductance characteristics pose a challenge for control of grid-connected inverter with LCL filter. In this paper, the variable inductance conundrum is discussed and a modified direct digital control method based on a variable-structure inductance estimation model that takes into consideration wide nonlinear variation in both inverter- and grid-side inductances is proposed. The proposed method is shown to have better grid-voltage harmonic rejection and improved stability margins. However, investigation of stability which is conventionally based on nominal values of filter inductors cannot predict instabilities over the entire range of inductance variation. Hence, a parametric approach to conventional stability methods with a parameter space defined by variation in actual and estimated inductance is explored in this paper. The effect of line impedance on stability is also investigated with impedance-based stability criterion by considering line inductance as an additional dimension in the parameter space. A pattern in stability margins is observed due to inductance variation, with inductance at its minimum being most vulnerable to instability. Experimental results measured from a 5 kW single-phase grid-connected inverter with various LCL filters have verified the feasibility of the proposed control method. The experimental results also match the analytical results with reasonable accuracy. [ABSTRACT FROM AUTHOR]

This paper proposes an improved zero current detection for critical conduction mode (CRM) control, which can compensate the input current distortion caused by the signal propagation delay and the existence of the negative resonance current. A unified variable on-time calculation method is also proposed to unify the formulas under the zero-voltage-switching condition and the valley-switching condition. Since these two methods are dependent on the boost inductance and device junction capacitance, which may be different from the nominal values, effort is needed to compensate the deviation on these two parameters. In this paper, an online monitoring method is proposed to compensate the numerical deviation. The proposed method only needs to sense the input voltage, output voltage, and the reverse flow time of the inductor current, leading to a high power quality in the entire input and load conditions. The experimental results of the proposed methods are demonstrated on a 200-W GaN-based CRM boost power factor correction prototype. With the proposed methods, the input current total harmonic distortion is only 0.78% at 110 VAC input with full load and 2.1% at 220 VAC input with full load. [ABSTRACT FROM AUTHOR]

This paper proposes a high-efficiency single-phase T-type boundary conduction mode (BCM) microinverter. The conventional full-bridge BCM microinverter has achieved zero voltage switching (ZVS) and thereby improved the efficiency, but it suffers from high switching losses under light load conditions. The proposed T-type BCM microinverter reserves ZVS and uses a multilevel technique to further decrease the switching losses. The BCM operation with multilevel technique will have too low switching frequency when the grid voltage approaches half of the dc link voltage. To solve this problem, this paper adopts a third operation mode for the T-type switching leg to maintain the switching frequency above a minimum value. The corresponding mode transitions are also detailed to ensure a smooth operation. Because of the turn-offdelay of the freewheeling transistor, the actual lower current boundary deviates from the programmed one, which will distort output current. To address this issue, this paper also proposes a boundary compensation method. A prototype has been built for performance verification, which can test both full-bridge and T-type topology. Compared with the full-bridge BCM microinverter, the proposed T-type BCM microinverter has a higher efficiency over the whole load range. [ABSTRACT FROM AUTHOR]

In this paper, a new soft-switching bridgeless single-phase power factor correction (PFC) converter is presented and analyzed. Employing an auxiliary switch, the input current dead angle that is the main drawback of the existing buck-type PFCs is omitted, and thus, the power factor (PF) is improved, which is the main contribution of the paper. Proposed PFC converter operates under discontinuous conduction mode (DCM) and draws sinusoidal input current from power supply inherently. All switches and diodes are turnedonandoffunder soft switching, which leads to low switching losses and elimination of diode reverse recovery problems. Also, minimum numbers of semiconductor devices are in the power flow path that reduce the conduction losses. A 120-W laboratory prototype is implemented and experimental results verify the validity of theoretical analysis and show efficiency of 92.1%. In addition, total harmonic distortion (THD) of 3.3% is achieved and the input current harmonics complies with IEC61000-3-2 Class D requirements. [ABSTRACT FROM AUTHOR]

Power converters and electric motor drives when tightly regulated behave as constant power loads. These loads are different from resistive loads and have destabilizing negative impedance characteristics, which impact a system's stability. A boost converter is intrinsically nonlinear and is a nonminimum phase system at the output voltage with respect to the control input. The linear approximation of this boost converter loaded with a constant power load has a zero and poles in the right half of the $s$ -plane, making the system unstable and very difficult to control. Control techniques that employ some form of system inversion cannot be implemented for a nonminimum phase system. This paper describes a technique to modify the nonminimum phase boost converter to a minimum phase for a constant power load, further implementing the input–output linearization technique to stabilize the system. This paper also provides a methodological analysis of the problem followed by the proposed solution. Furthermore, it verifies the analysis of the proposed solution through simulation and experimental results. [ABSTRACT FROM AUTHOR]

A high step-up dc–dc converter is proposed in this paper. The presented converter benefits from some advantages such as high voltage gain and continuous input current, which makes it suitable for the renewable energy applications. The presented converter is based on the SEPIC converter. However, the converter voltage gain is improved by employing a coupled inductor and two voltage multipliers. A passive clamp circuit is also added to the proposed converter that increases the voltage gain and reduces the voltage stress on the main switch. Thus, a switch with low $R_{{\text{DS(on)}}}$ will be needed that decreases the conduction loss. Besides, the voltage stress on the output diode in the proposed converter is reduced, which alleviates reverse recovery problem. The steady-state analysis of the proposed converter is discussed in this paper. The analysis is verified with experimental results under the output power of 245 W. [ABSTRACT FROM AUTHOR]

In this paper, a high step-up quasi-Z Source (QZS) dc–dc converter is proposed. This converter uses a hybrid switched-capacitors switched-inductor method in order to achieve high voltage gains. The proposed converter have resolved the voltage gain limitation of the basic QZS dc–dc converter while keeping its main advantages, such as continuous input current and low voltage stress on capacitors. Compared to the basic converter, the duty cycle is not limited, and the voltage stress on the diodes and switch is not increased. In addition to these features, the proposed converter has a flexible structure, and extra stages could be added to it in order to achieve even higher voltage gains without increasing the voltage stress on devices or limiting the duty cycle. The operation principle of the converter and related relationships and waveforms are presented in the paper. Also, a comprehensive comparison between the proposed and other QZS based dc–dc converters is provided which confirms the superiority of the proposed converter. Simulations are done in power systems computer aided design (PSCAD) in order to investigate the maximum power point tracking (MPPT) capability of the converter. In addition, the valid performance and practicality of the converter are studied through the results obtained from the laboratory built prototype. [ABSTRACT FROM AUTHOR]

Multiple coupled inductors are used in power electronics to improve the dynamic cross regulation and to reduce mass and volume, mainly in high performance application, such as space or defense, where manufacturing cost is not the main driver. These elements can be modeled with its inductance matrix which is a symmetric and positive semidefinite matrix. The inductance matrix eases circuit analysis, many known circuital models are directly related to it and it can be used in SPICE simulation via its coupling coefficient component, which can be identified as the normalized matrix of the inductance matrix. Therefore, a precise and correct measurement technique of the inductance matrix or coupling coefficient matrix is needed. This paper analyzes different measuring techniques described in the technical literature and proposes a new method to measure the coupling coefficient or inductance matrix of tight coupled or dissimilar turns’ number windings, where other methods fail. A discussion follows, to know the influence of parasitic elements in the accuracy of the new proposed method called resonance (RE) method. The paper adds three experimental examples to verify the theoretical study and concludes that the RE method provides correct values of the coupling coefficient $k$ of tight coupled or dissimilar turns’ number windings compared to other measurement techniques. [ABSTRACT FROM AUTHOR]

This paper introduces a new bidirectional single-phase inverter topology. The proposed topology has three ports: a dc port, an ac port, and a ripple port. The ac and dc ports are bidirectional to support rectifier or inverter operation. A small inductor, which is of alternating current, exchanges power between different ports of the single-phase system. The proposed topology is capable of accomplishing voltage step-up or step-down, suppressing the ripple power, and performing inversion or rectification operation in one stage of power conversion. The proposed configuration offers an active decoupling function, which not only eliminates the double-frequency ripple power at the dc port but also achieves minimum capacitance requirements to minimize the size of the decoupling capacitor. This facilitates the use of a very small thin-film capacitor, which offers a much longer life-cycle and higher reliability compared with a bulky electrolytic capacitor. A control approach is also developed to regulate the dc-port and ac-port currents and manage the ripple power through proper distribution of power between each port. Moreover, a very small capacitor can be placed in parallel with the inductor to reinforce the proposed configuration with soft-switching operation, which enhances the overall efficiency and minimizes the voltage stress over the semiconductor devices. This converter is capable of accommodating an arbitrary number of dc or single-phase ac sources and/or loads configuring a multiple-input multiple-output inverter without introducing any additional passive elements or sacrificing the performance of the inverter. The primary focus of this paper is dc-to-ac conversion mode of operation, in spite of the fact that it can easily be configured to serve as a rectifier. Experimental and simulation results are presented to validate the operation of the proposed topology and its control strategy. [ABSTRACT FROM AUTHOR]

Most of the two-stage converters for electric bike battery charging comprise of a boost converter for power factor correction (PFC) followed by a dc–dc converter with universal input voltage. These two-stage conversions suffer from poor efficiency and increased component count. In this paper, a single-stage switched inductor Cuk converter based PFC converter is proposed, which offers high step-down gain, low current stress, high efficiency, and reduced component count. The operational analysis and design equations for various components of the proposed converter are carried out in continuous current mode. This paper presents mathematical modeling, analysis, simulation, and experimentation on the proposed converter rated for 500 W, 48 V/10.4 A. The performance investigation of the proposed converter with respect to power quality indices like voltage total harmonic distortion (THD), current THD, and total power factor is carried out with various types of loads such as resistive load and battery load in both constant voltage (CV) and constant current (CC) mode. Furthermore, the dynamic performance of the proposed converter with battery charging is investigated in CV mode and CC mode with respect to the wide range of supply variations. [ABSTRACT FROM AUTHOR]

This paper proposes a new high-efficiency photovoltaic (PV) converter for grid connection through a high-leg delta transformer. The converter is composed of a symmetrically connected boost converter and three half-bridge inverters. One of the three half-bridge inverters is connected to the boost converter, and the others are directly connected to the PV terminals. As a result, this circuit configuration enables to reduce the power losses in both boost converter and inverters. This paper also proposes a new cooperative control method between the symmetrically connected boost converter and inverter. The control method can reduce the average switching frequency to 75% of that in a conventional one, resulting in a great reduction in the switching power loss. Experimental results confirm that the proposed circuit configuration makes it possible to improve its European efficiency from 91.6% to 94.5%. Moreover, system performance is evaluated on the assumption of maximum power point tracking operation. [ABSTRACT FROM AUTHOR]

This paper presents a unified framework for the modeling, analysis, and design of load-independent Class E and Class EF inverters and rectifiers. These circuits are able to maintain zero-voltage switching and, hence, high efficiency for a wide load range without requiring tuning or use of a feedback loop, and to simultaneously achieve a constant amplitude ac voltage or current in inversion and a constant dc output voltage or current in rectification. As switching frequencies are gradually stepping into the megahertz (MHz) region with the use of wide-bandgap (WBG) devices such as GaN and SiC, switching loss, implementing fast control loops, and current sensing become a challenge, which load-independent operation is able to address, thus allowing exploitation of the high-frequency capability of WBG devices. The traditional Class E and EF topologies are first presented, and the conditions for load-independent operation are derived mathematically; then, a thorough analytical characterization of the circuit performance is carried out in terms of voltage and current stresses and the power-output capability. From this, design contours and tables are presented to enable the rapid implementation of these converters given particular power and load requirements. Three different design examples are used to showcase the capability of these converters in typical MHz power conversion applications using the design equations and methods presented in this paper. The design examples are chosen toward enabling efficient and high-power-density MHz converters for wireless power transfer (WPT) applications and dc/dc conversion. Specifically, a 150-W 13.56-MHz Class EF inverter for WPT, a 150-W 10-MHz miniature Class E boost converter, and a lightweight wirelessly powered drone using a 20-W 13.56-MHz Class E synchronous rectifier have been designed and are presented here. [ABSTRACT FROM AUTHOR]

This paper discusses dynamic behavior of a dual-active-bridge (DAB) dc–dc converter. Conventional phase-shift control methods for the DAB converter may cause dc offsets in both inductor current and transformer magnetizing current in transient states. The dc offset in the inductor current would introduce an excessive peak current through the switching devices. The dc offset in the magnetizing current may induce magnetic-flux saturation. Conventional methods simultaneously turn on and off the diagonal switches in each H-bridge converter and produce a square-wave voltage with a 50% duty ratio. In contrast, the proposed method in this paper independently controls each switch to modify the duty ratio in transient states. This paper clearly derives the requirements of each switch to eliminate the dc offsets in both currents with a settling time shorter than half the switching period. Experimental results using a 5-kW 20-kHz system verify the validity of the proposed control method, which is effective not only in a single step change, but also in a continuous change in the phase-shift reference. [ABSTRACT FROM AUTHOR]

Constant on-time V^2 control for point-of-load buck converters has instability issues in the cases that the output capacitors' RC time constants are small. This paper intensively studies the proposed solution using capacitor current ramp compensation, which is a superior solution featuring fast response and universality. A frequency-domain small-signal model based on describing function method is proposed in this paper. The time-domain large-signal response to the load step change is analyzed. The analysis illustrates the unique transient response behaviors of the capacitor current ramp compensated V^2 control. The design optimization methodology based on frequency-domain and time-domain analysis is presented. The proposed model and the design guidelines are verified by the experimental results. [ABSTRACT FROM AUTHOR]

Class $E^2$ DC–DC converter composed of Class $E$ power amplifier (PA) and rectifier is a promising candidate for MHz wireless power transfer. It is soft-switching based and able to achieve high efficiency at MHz frequency. However, the converter implemented through traditional static design is sensitive to the variations of operation condition. Its performance gets deteriorated when DC load and coil coupling deviate from their respective optimum values. This paper demonstrates that the degradation of system efficiency is mostly due to the mismatch of PA load, and the efficiency drop can be efficiently improved by adding an L-type impedance matching network (IMN) after PA. A fixed IMN is sufficient to maintain a high efficiency, while a tunable IMN is required to ensure stable output power when operation condition dramatically changes. Key techniques, particularly system-level optimization, are discussed in this paper that ensure high efficiency over a wide range of variation in operation condition and also with reduced capacitor/inductor tuning ranges in the IMN. The 6.78-MHz Class $E^2$ DC–DC converters with and without the fixed/tunable IMN are fabricated and measured for validation purposes. The experimental results show that both high efficiency ( $>$66%) and stable output power (around 9 W) are maintained for the tunable converter when there are variations in the DC load and coil coupling. [ABSTRACT FROM AUTHOR]

This paper proposes a variable off-time control method for a single-phase microinverter operating in the discontinuous conduction mode (DCM) for efficiency improvement. First, the fixed off-time control method is analyzed. The concept is to fix the off-time of the active switch throughout a line cycle for all output powers and scale the on-time of the active switch to shape a sinusoidal output current. Then, based on the fixed off-time control method, a variable off-time control method is proposed to modulate the preset fixed off-time in order to decrease the switching frequency during ac line zero-crossings and light load conditions. Compared with existed fixed-frequency DCM control or boundary conduction mode control, the variable off-time control is more flexible to optimize the efficiency under different load conditions as the switching frequency range can be automatically adjusted according to the output power. The switching frequency is high at heavy loads to limit the maximum peak current and is low at light loads to increase the light load efficiency. In addition, a predictive on-time method is adopted to simplify inverter control and reduce hardware costs. The parameter design principle is detailed in this paper. A 300 W prototype is built to verify the performance of the proposed method. [ABSTRACT FROM AUTHOR]

This paper proposes a new single-phase single-stage switched-boost inverter with four switches. Like the quasi-Z-source inverter and quasi-switched boost inverter (qSBI), the proposed inverter has the main features as continuous input current, buck/boost voltage with single-stage conversion, and shoot-through immunity. Compared to the qSBI, the proposed inverter uses one more capacitor and one less switch. This paper presents the operating principles, pulse-width modulation control strategy, parameter design guidelines, and simulation results for the proposed inverter. To verify the performance of the proposed inverter, an 800-W prototype was built with an 110 V/50 Hz output voltage in stand-alone and grid-connected modes. The simulation and experimental results matched those of the theoretical analysis. [ABSTRACT FROM AUTHOR]