Showing papers on "Buck–boost converter published in 2020"

Generalized State Space Average Model for Multi-Phase Interleaved Buck, Boost and Buck-Boost DC-DC Converters: Transient, Steady-State and Switching Dynamics

Abstract: This paper presents a generalized state space average model (GSSAM) for multi-phase interleaved buck, boost and buck-boost converters. The GSSAM can model the switching behavior of the current and voltage waveforms, unlike the conventional average model which can model only the average value. The GSSAM is used for the converters with dominant oscillatory behavior such as resonant converters, high current ripple converters, and multi-converter systems. The maximum current and voltage through the system can be predicted by modeling the switching behavior of voltage and current. The GSSAM in the literature is introduced for single-phase converters only, and it is not introduced for multi-phase converters due to the high complexity associated with it. Hence, the GSSAM for multi-phase buck, boost and buck-boost converters are introduced in this paper and the proposed models can fit with converters of any number of phases. The number of operating phases in the multi-phase interleaved converters is proportional with the output power to achieve the maximum efficiency over the operating range. Therefore, the proposed GSSAMs can describe the operation at any number of operating phases with switching dynamics of phases. The proposed GSSAM is validated by comparing the transient and steady-state dynamics between the GSSAM and a switching model from PLECS.

Non-Isolated High-Gain Triple Port DC–DC Buck-Boost Converter With Positive Output Voltage for Photovoltaic Applications

Abstract: The solar PV based power generation systems are growing faster due to the depletion of fossil fuels and environmental concerns Combining PV panels and energy buffers such as battery through multi-port converter is one of the viable solutions to deal with the intermittency of PV power The goal of this paper is to design and analyze the proposed triple port DC-DC buck-boost converter for high step-up/step-down applications It has two unidirectional ports (port-1 and port-3) and one bi-directional port (port-2) for harnessing photovoltaic energy and charging the battery At port-1, the combined structure of buck and buck-boost converter is used with a particular arrangement of switches and inductors The step-up/step-down voltage conversion ratio is higher than the conventional buck-boost converter, and the polarity of the output voltage is maintained positive The battery is added at the bi-directional port, for the storage of energy through the bi-directional boost converter The switches operate synchronously for most of the modes making the control strategy simple The characteristics and modes of operation along with a switching strategy, are elaborated Experimental results are presented which validate the agreement with the developed theoretical expectation

A High Efficiency Nonisolated Buck–Boost Converter Based on ZETA Converter

Abstract: In this paper, a new transformerless buck–boost converter based on a ZETA converter is introduced. The proposed converter has the ZETA converter advantages, such as buck–boost capability, input-to-output dc insulation, and continuous output current. The suggested converter voltage gain is higher than the classic ZETA converter. In the presented converter, only one main switch is utilized. The proposed converter offers low voltage stress of the switch; therefore, the low on -state resistance of the main switch can be selected to decrease the losses of the switch. The presented converter topology is simple; hence, the control of the converter is simple. The converter has the continuous output current. The mathematical analyses of the presented converter are given. The experimental results confirm the correctness of the analysis.

99% Efficient Isolated Three-Phase Matrix-Type DAB Buck–Boost PFC Rectifier

Abstract: Three-phase power factor correction rectifiers are an essential area of power electronics, supplying a direct current load with tens of kilowatts, or more, from the public three-phase mains and achieving sinusoidal input currents. In many applications, isolation is required between the mains and the load, for example, due to safety reasons or different grounding schemes. This paper describes the modulation, design, and realization of a buck–boost-type, unity-power-factor, isolated matrix-type, dual-active-bridge, three-phase rectifier. It uses a circuit similar to a conventional dual-active-bridge converter, but employs a direct matrix converter to connect the high-frequency transformer's primary winding to the mains. A soft-switching modulation scheme is proposed and comprehensively analyzed, deriving closed-form solutions and numerical optimization problems to calculate switching times that achieve minimal conduction losses. Based on this analysis, the design of an 8-kW 400-V rms three-phase ac to 400-V dc prototype is discussed, striving for the highest possible efficiency. Using 900-V SiC mosfet s and a transformer with an integrated inductor, a power density of ${\text{4}}\; {\text{kW}\cdot \text{dm}^{-3}}$ ( ${\text{66}}\; {\text{W}\cdot \text{in}^{-3}}$ ) is achieved. Measurement results confirm an ultrahigh full-power efficiency of 99.0% at nominal operating conditions and 98.7% at 10% lower input voltage.

Analysis of a synergetically controlled two-stage three-phase DC/AC buck-boost converter

Abstract: Three-phase DC/AC power electronics converter systems used in battery-powered variable-speed drive systems or employed in three-phase mains-supplied battery charger applications usually feature two power conversion stages. In both cases, typically a DC/DC stage is attached to a three-phase DC/AC stage in order to enable buck-boost functionality and/or a wide input-output voltage operating range. However, a two-stage solution leads to a high number of switched bridge-legs and hence, results in high switching losses, if the degrees of freedom available for controlling the overall system are not utilised. If the DC/DC stage is used to vary the DC link voltage with six times the AC-side frequency, a pulse width modulation (PWM) of always only one phase of the DC/AC stage is sufficient to achieve three-phase sinusoidal output currents. The clamping of two phases (denoted as 1/3 PWM) leads to a drastic reduction of the DC/AC stage switching losses, which is further accentuated by a DC link voltage which is lower than for the conventional modulation schemes. This paper details the operating principle of a three-phase buck-boost converter system using 1/3 PWM and outlines an appropriate control system design. Subsequently, the switching losses and the voltage/current stresses on the converter components are analytically derived. There, a more than 66% reduction of the DC/AC stage switching losses is calculated without any increase of the stress on the remaining converter components. The theoretical considerations are finally verified on a hardware demonstrator, where the proposed modulation strategy is experimentally compared against several conventional modulation techniques and its clear performance advantages are validated.

Analysis and Modeling of a New Coupled-Inductor Buck–Boost DC–DC Converter for Renewable Energy Applications

Abstract: A new coupled-inductor buck–boost converter (CIBuBoC) is proposed in this article. In the proposed CIBuBoC, an ultra-high step-up/step-down voltage conversion ratio and step-up/step-down boundary adjustment are achieved compared to the other related buck–boost converters using two power switches with simultaneous operation along with a coupled inductor. This circuit has a simple structure with two cascade semistage and some features including ultra-extended output voltage, continuous input current with low ripple, positive polarity of the output voltage, and common ground. These features make the CIBuBoC more suitable for many applications such as photovoltaic systems. Moreover, the voltage stress across each power switch is much lower than the other buck–boost converters, which led to power mosfet s selection with lower drain-source on -resistance ( R ds). Therefore, the proposed converter has also enough high efficiency. All steady-state and stress analysis, and also, comparisons with other related converters in continuous conduction mode are provided in detail. Also, using the state-space averaging technique, the low-frequency behavior of the proposed CIBuBoC is studied completely. Experimental results of a 100-W step-up 30–200 V and a 35-W step-down 30–22 V confirm the theoretical advantages of the proposed circuit.

Three-Phase Bidirectional Buck-Boost Current DC-Link EV Battery Charger Featuring a Wide Output Voltage Range of 200 to 1000V

Abstract: High power EV chargers connected to an AC power distribution bus are employing a three-phase AC/DC Power Factor Correction (PFC) front-end and a series-connected isolated DC/DC converter to efficiently regulate the traction battery voltage and supply the required charging current. In this paper, the component stresses and the design optimization of a novel two-stage three-phase bidirectional buck-boost current DC-link PFC rectifier system, realized solely with SiC power MOSFETs and conveniently requiring only a single magnetic component, are introduced. This topology offers a high efficiency in a wide operating range thanks to the synergetic operation of its two stages, the three-phase buck-type current source rectifier stage and the subsequent three-level boost-type DC/DC-stage, which makes it suitable for on-board as well as off-board charger applications. The calculated voltage and current component stresses of the proposed converter system, considering an output voltage range of 200 to 1000V and up to 10kW of output power, help to identify its operating boundaries, maximizing the utilization of the power semiconductors and of the DC-link inductor. The optimum values of the circuit parameters are selected after evaluating the converter average efficiency $\bar \eta $ and volumetric power density ρ in the Pareto performance space and analyzing its design space diversity, focusing on the semiconductor losses and on the characteristics of the inductor. Considering typical EV battery charging profiles, i.e. taking both full-load and part-load operation into account, a power converter realization featuring $\bar \eta = 98.5\% $ and ρ =13.9kW/dm3 is achieved.

Analysis, Modeling and Implementation of a Switching Bi-Directional Buck-Boost Converter Based on Electric Vehicle Hybrid Energy Storage for V2G System

Abstract: This paper presents a switching bi-directional buck-boost converter (SBBBC) for vehicles-to-grid (V2G) system. The topology can provide an energy bi-directional flow path for energy exchange between the Li-battery/supercapacitor (SC) hybrid energy storage system (HESS) of the electric vehicle and the grid. This topology not only has buck-boost capability, but also has the function of energy management. In this paper, the state-space averaging method is used to analyze the stability of the topology in boost and buck modes. The control strategy is given according to the state of charge (SOC) of the energy storage system to ensure that the output voltage and current are stable. And the Li-battery is charged in constant current (CC) and constant voltage (CV) mode. The voltage and current controllers are designed in the frequency domain based on bode plots. Finally, the electrical feasibility of the topology, the suitability of the design controller and control strategy are verified by simulation and experiment.

Two-Phase, Dual Interleaved Buck–Boost DC–DC Converter for Automotive Applications

Abstract: A two-phase buck–boost converter utilizing dual interleaving is presented in this article. The dual interleaving consists of an interphase transformer (IPT) that doubles the ripple frequency together with two conventional buck–boost switching arms, mitigating the inductor ripple current and aiding to increase the power density of the converter. A description of the design and selection of the power devices is presented for a 32-kW, 75-kHz dual interleaved SiC prototype with an IPT, such that a power density of 7.4 kW/kg is achieved. The operation of the circuit is verified experimentally using a prototype with 315–385 V supply range and 350-V output voltage, achieving 97.1% peak efficiency at 32 kW. The experiments reveal that the interleaved coupled currents are equalized without an active balancer.

Development of an Improved Input-Parallel Output-Series Buck-Boost Converter and Its Closed-Loop Control

Abstract: In this article, design and development of a new input-parallel output-series buck-boost converter (IOBBC) is presented, which produces high voltage gain, multiple output voltage, better efficiency, and exhibits lesser ripples in output voltage as well as in source current. IOBBC is based on the parallel–series combination of two different topologies of buck-boost converters (BBCs), where two converters operate in an interleaving state with 180° phase displacement during one complete switching cycle. The proposed converter produces noninverting output voltage unlike the conventional single switch based BBC and will produce wider range of output voltage even with a small change of duty cycle. A closed-loop controlled IOBBC has been fabricated utilizing a generalized optimized Type-III controller that has been designed by ‘‘ K -factor” method and particle swarm optimization technique for maintaining overall stability and to produce satisfactory dynamic response of proposed converter. IOBBC exhibits better performance than interleaved buck-boost converter in terms of voltage gain, efficiency, dynamic response, and ripple content in source current and in output voltage.

Bidirectional Buck–Boost Current-Fed Isolated DC–DC Converter and Its Modulation

Abstract: In this article, a bidirectional buck-boost current-fed isolated dc-dc converter is proposed to realize the bidirectional and buck/boost voltage conversion and accordingly extend the operating range. The basic modulation is proposed and the operation principle is analyzed in detail. Furthermore, the voltage conversion ratio as the functions of the duty cycle ratio of the buck unit and shoot through ratio of the H-bridge converter is derived. The control rule of the two controllable variables is determined based on minimizing the average inductor current. In addition, the optimal starting moment of active period of the buck unit in the switching cycle is determined based on minimizing the inductor current ripple. The detailed experimental results verify the correctness and feasibility of the proposed topology and modulation.

Highly Efficient Single-Phase Buck–Boost Variable-Frequency AC–AC Converter With Inherent Commutation Capability

Abstract: This paper introduces a novel single-phase buck–boost noninverting variable-frequency ac–ac converter that offers higher efficiency compared to the competitors. This converter utilizes a lower number of semiconductors. A simple and flexible switching strategy is also proposed, which generates the desired output waveform avoiding unnecessary high-frequency switching operation of semiconductor devices. A high reliable operation due to the elimination of the input source shoot-through risk, an inherent commutation capability that mitigates the voltage spikes across the semiconductors, a lower semiconductors rating requirement, an improved input current waveform quality, and a smaller required input filter inductor are the main advantages of the proposed converter. Thus, the proposed converter can be successfully applied to many industrial applications such as medium-frequency transformer isolation for traction and wind turbine converters, ac–dc high-voltage conversion based on Cockcroft–Walton circuit and induction heating systems. The theoretical achievements and claims are all confirmed through extensive experimental tests on a 200-W laboratory setup.

A Single-Inductor Multiple-Output Buck/Boost DC–DC Converter With Duty-Cycle and Control-Current Predictor

Abstract: A single-inductor multiple-output (SIMO) buck/boost dc–dc converter with average-current control is presented in this article. With the proposed duty-cycle and control-current predictor, fast and robust reference tracking of inductor current is achieved. The conventional charge-balance method is modified together with an auto-tuning-divider-based duty generator to release the cross-regulation to the last channel. Moreover, an anti-right-half-plane zero method is also proposed to suppress cross-regulation during large loading transient when the SIMO dc–dc converter operating in the boost mode. The proposed SIMO buck/boost dc–dc converter has four output channels which are adaptive to both boost and buck operations and is implemented in a standard 0.35-μm CMOS process. Measurement results show that the proposed dc–dc converter achieves a peak efficiency of more than 89% at a total output power of about 0.5 W, load transient's response time of less than 40 μs, cross-regulation within 0.05 V/A when a 300-mA loading transient is applied to a boost channel.

Low-Voltage Stress Buck-Boost Converter With a High-Voltage Conversion Gain

Abstract: The conventional buck-boost converter has the advantages of simple structure, low cost, and the capability to achieve both voltage step-up and down. However, due to the negative impacts of the parasitic parameters of the device, the voltage conversion gain of the conventional buck-boost converter is greatly limited. A low-voltage stress buck-boost converter with a high voltage conversion gain based on a coat circuit is proposed in this paper to address the problem. Similar to a coat that can enhance human’s resistance to cold weather, by adding the proposed coat circuit to the conventional buck-boost converter, not only the range for the voltage conversion can be extended, but also the voltage stresses of the semiconductor components are effectively reduced. In this work, comprehensive analysis on the working principles and performance characteristics of the coat converter are provided. Experimental results are obtained and analyzed to validate of the theoretical analysis based on a 300W closed-loop prototype platform.

11.7 A Voltage-Tolerant Three-Level Buck-Boost DC-DC Converter with Continuous Transfer Current and Flying Capacitor Soft Charger Achieving 96.8% Power Efficiency and 0.87µs/V DVS Rate

Abstract: In recent years, buck-boost converters have been widely utilized for battery-powered mobile systems such as RF power amplifiers, battery chargers, and LED drivers. However, in a wide battery voltage range, they face challenges including dynamic voltage scaling (DVS), wide load current range, and dynamic line/load transients while ensuring reliability for an industrial usage. To resolve these issues, the conventional buck-boost (CBB) converter should overcome the characteristic of discontinuity in the output transfer current (OTC) which causes degradation of loop dynamics and transient response. Several past works with continuous OTC have been proposed to resolve these problems, but their voltage conversion ratios are limited [1], [2]. Moreover, in [3], [4], a high-voltage (HV) process, which necessitates large active area and incurs high fabrication cost, is required to withstand voltage stresses over 10V (2×V IN ) applied across power switches. To overcome the above challenges, this paper proposes a voltage-tolerant three-level buck-boost (TLBB) converter. The TLBB has continuous OTC and uses only normal 5V CMOS devices for its switches. In addition, a voltage-tolerant dual channel-interleaved three-level buck-boost (DTLBB) converter is suggested for applications [5] requiring a wide range of load current and high conversion ratio while supporting fast DVS transition.

Single-Stage Bidirectional Buck–Boost Inverters Using a Single Inductor and Eliminating the Common-Mode Leakage Current

Abstract: This paper presents novel single-phase single-stage buck–boost inverters. The proposed inverters provide buck–boost operation for a wide variation of the input dc voltage. In addition, the proposed inverters are bidirectional and provide reactive power. Further, they require only one inductor. The proposed inverters also eliminate the common-mode leakage current by connecting the output neutral to the midpoint of input capacitors or directly to input voltage sources. Therefore, they are well suitable for photovoltaic applications. Although six switches are required, two switches are working at line frequency, resulting in negligible switching loss. Of the four remaining switches, only two are switching at high frequency at a time. The circuit operations are demonstrated through the analysis of the proposed inverters. A 120 Vrms/60 Hz/400 W hardware prototype was constructed and tested. The experimental results verified the theoretical analysis.

Buck-Boost-Buck-Type Single-Switch Multistring Resonant LED Driver With High Power Factor and Passive Current Balancing

Abstract: An integrated buck-boost-buck-type single-switch multistring resonant light-emitting diode (LED) driver is proposed and analyzed. It combines buck-boost and buck converters to achieve passive current balancing and power factor correction. With this circuit configuration, the proposed LED driver employs only one low-side connection active switch, resulting in a very simple control requirement involving one closed-loop controller for regulating one output current. Other output currents can be balanced automatically by resonant capacitor and storage capacitors, making the control strategy economical. In addition, high efficiency is achieved due to single-stage power conversion. Taking three-string LED driver as an example, the proposed buck-boost-buck-type single-switch LED driver is studied in terms of operating principle, current balancing principle, power factor (PF) analysis, voltage gain, and key circuit parameter design. Finally, an 84-W high-PF three-string LED driver prototype with 94.3% peak efficiency is built to verify the analytical results.

Hybrid Buck–Boost Multioutput Quasi-Z-Source Converter With Dual DC and Single AC Outputs

Abstract: This article presents two hybrid multioutput buck–boost quasi-Z-source converters (q-ZSCs) capable of giving two dc and one ac outputs simultaneously from a single dc input. One dc and the ac outputs of the proposed multioutput q-ZSCs have both buck and boost capabilities and the other dc output has the property of boosting the input voltage, thereby capable of giving a wide range of voltage gain both for dc and ac outputs. The rationale behind proposing two variants of the hybrid multioutput q-ZSCs is to have more flexibility on voltage gains as per the load requirements. The proposed converters are derived from the quasi-Z-source concept and hence inherit all the properties of q-ZSI, which realize buck/boost, single-stage inversion, and power conditioning with improved reliability along with inherent shoot-through protection capability. All the three outputs of the proposed converters can be independently controlled making them suitable for various applications. The proposed converters can be utilized for various modern multioutput dc–dc and dc–ac power conversion applications, such as renewables and the uninterrupted power supplies. Detailed steady-state operation, loss/efficiency analysis of the proposed converter, and discussion on the hybrid pulsewidth modulation are presented in this article. In order to bring out the advantages of the proposed multioutput converter, a detailed comparative analysis among the proposed and other closely related existing multioutput converters is carried out in this article. A 310-W prototype is developed to verify the performance of the proposed multioutput buck–boost q-ZSC.

Three-Phase Sinusoidal Output Buck-Boost GaN Y-Inverter for Advanced Variable Speed AC Drives

Abstract: Motor drive systems supplied by a fuel-cell/battery are especially demanding when it comes to the design of the inverter. Besides a high performance (high efficiency η and power density ρ), the inverter has to cope with the wide DC voltage variation of the fuel-cell/battery that supplies the motor drive. A promising three-phase inverter topology, denoted as Y-VSI, is presented in this paper. The Y-VSI is a modular three-phase inverter, and comprises three identical phase-modules connected to a common star “Y” point. Each phase-module is equivalent to a buck-boost DC/DC converter, which allows the AC output voltages to be higher or lower than the DC input voltage. Thereby, the Y-VSI effectively copes with the wide variation of the fuel-cell/battery voltage. Each phase-module can be operated in a similar fashion to a conventional DC/DC converter, independently of the remaining two phases. Accordingly, a straightforward and simple operation/control of the Y-VSI is possible. In addition, the Y-VSI features an integrated output filter. This allows for continuous/sinusoidal motor voltage waveforms, eliminating the need of an additional filter between the inverter and the motor. This paper details the operating principle of the Y-VSI, and comparatively evaluates two modulation strategies. In order to validate the proposed concepts, a Y-VSI hardware prototype is assembled within the context of a high-speed motor drive. In the investigated drive system, a fuel-cell supplies the Y-VSI, which in return controls a 280 krpm 1 kW electric compressor. The Y-VSI hardware prototype is compared against a state-of-the-art hardware prototype, which features two energy conversion stages. It is shown that the Y-VSI is ∆η = +2.3% more efficient and at the same time ∆ρ = +10% more power dense compared to the conventional inverter solution.

Manitoba Rectifier—Bridgeless Buck–Boost PFC

Abstract: This paper presents a new bridgeless buck–boost power factor corrector with the use of the active virtual ground technique, which is named as the Manitoba Rectifier. The proposed topology can convert the grid ac voltage into a wide range of voltage outputs within a single-stage circuit. It is in a bridgeless structure and simple in design. During the operation, an LC filter is generated at the system input, where continuous grid current is guaranteed in a buck–boost characteristic topology. In addition, the filter capacitor helps to clamp the voltage ripple between the grid and the output bus terminal. Both leakage current and common mode noise are kept in a relatively small value. Thus, a single-stage and low common-mode buck–boost converter system is built. The proposed topology is successfully implemented on an 800 W prototype, and the performance is experimentally verified, which shows good agreement with the theoretical findings.

A Lossless Turn- on Snubber for Reducing Diode Reverse Recovery Losses in Bidirectional Buck/Boost Converter

Abstract: In this letter, we introduce a simple turn- on snubber for the conventional bidirectional converter. This snubber notably reduces the current reduction rate of the converter main diodes at turn- off . Hence, the reverse recovery losses, which are the dominant losses in the bidirectional converter, are almost eliminated. These features are achieved with a minimum circulating current and no extra voltage or current stress. The conventional bidirectional converter with the proposed snubber is analyzed, and to confirm the analysis, the experimental results are presented.

Current Control of the Coupled-Inductor Buck–Boost DC–DC Switching Converter Using a Model Predictive Control Approach

Abstract: Coupled-inductor buck–boost dc–dc switching converter has emerged as an alternative to manage power in several hybrid system architectures. This is due to features such as a noninverting voltage step-up and step-down characteristic, high efficiency, wide bandwidth, and the possibility to regulate its input or output currents as has been reported in previous works. All of them are based on a small-signal linearized model around an operating point. In this article, a model predictive control strategy is proposed to increase the operation point domain. The proposal consists in the use of the mathematical model of the system in discrete time to obtain the optimal switching state to be applied in the converter based on a cost function optimization, which simultaneously improves the current tracking and reduces the converter power losses. Experimental results validate the proposal demonstrating that this is a good alternative for the control of this kind of power converters.

Noninverting Buck–Boost DC–DC Converter Using a Duobinary-Encoded Single-Bit Delta-Sigma Modulator

Abstract: This paper presents a delta-sigma modulation (DSM) control scheme for noninverting buck–boost (NIBB) converter that features a duobinary encoding for four power switch controls. The proposed scheme converts the single-bit output of the modulator into a 1.5-b signal to enable a three-phase operation comprising the charging, bypassing, and discharging phases. This control method reduces both switching and conduction losses by changing only two switches in each period, thus, achieving high conversion efficiency. A smooth mode transition is provided by the DSM controller, which automatically and continuously determines the operating mode of the converter. Thus, the dead zone can be effectively released with improved transient responses. Furthermore, the spurious tones in the output are effectively eliminated by the robust noise shaping capability of the modulator. The proposed DSM-based NIBB converter was implemented on a 180-nm CMOS. It regulated the output in the range of 2.0–4.6 V with input voltage of 2.5–5.0 V, and the maximal load current was 500 mA. The converter showed a peak efficiency of 94.8% at 90-mA load and the output voltage ripples were maintained under 18 mV. A low noise floor with the first spurious peak located –92 dBc below the signal was achieved across all mode operations. In addition, the converter occupied a small chip area of 1.51 mm2.

Investigation of single-stage transformerless buck–boost microinverters

Abstract: The conventional microinverters with transformers and multiple-stage system increases the cost, weight and size, lowering the effectiveness and power density of PV system. It is therefore desirable to prevent using these methods for a microinverter. However, extra care must be taken to prevent component stress, excess switching and conduction losses, ground leakage currents and harmonics. Several transformerless buck–boost inverters have lately been suggested to address various issues. Due to the availability of a number of buck–boost inverter-topology for the solar PV system, it is often difficult to identify when to choose the appropriate topology. Therefore, in order to present a clear view of the advancement of transformerless buck–boost inverters for next-generation grid-integrated PV systems, this article seeks to explore multiple buck–boost topologies with an extensive analytical comparison. Computer simulations for the 70 W system have been conducted in PLECS software to strengthen the results and comparisons, as well as to provide more insight into the features of the distinct topologies for the building-integrated photovoltaic implementation. At the later part, voltage and current stress in each component, efficiency and total harmonic distortion of the system are provided with a general summary, as well as, a technology roadmap.

Modeling, Design and Control of Non-isolated Single-Input Multi-Output Zeta–Buck–Boost Converter

Abstract: In this article, we focus on the analytical modeling of nonisolated single-input multiple-output (SIMO) dc–dc converters governed by linear differential algebraic equations (DAEs). The modeling challenge in nonisolated SIMO converters arises due to the switching among multiple DAEs governing the circuit. Averaged models of such converters, described by an ordinary differential equation, are derived using the notion of quasi-Weierstrass transformation. Using this technique, we derive the averaged model for a nonisolated Zeta–Buck–Boost (ZBB) converter. It is observed that the dynamics of the state variable corresponding to the algebraic constraint is uncontrollable and eliminating this state leads to a fourth-order completely controllable averaged model. This model is used to design a linear state-feedback controller for line regulation. In the case of bipolar SIMO converters, ZBB being an example, regulation of the two outputs can be achieved using any one of the two output integral states. Although the state-feedback controller successfully rejects the disturbance asymptotically, it is found that the deviations from the set point in the transient phase can be large. To see if smaller deviations can be achieved by appending the linear controller with a nonlinear term, we explore a nonlinear controller based on the Lyapunov redesign technique. Smaller deviations with complete disturbance rejection are possible if the disturbance is matched. When it is unmatched, small deviations are achieved at the expense of steady-state errors, whose estimate is explicitly found. The proposed model and control scheme are verified through a laboratory built hardware prototype.

A Reliable Single-Phase Bipolar Buck–Boost Direct PWM AC–AC Converter With Continuous Input/Output Currents

Abstract: In this article, a single-phase bipolar buck–boost direct pulsewidth-modulated ac–ac converter is proposed, comprised of six insulated-gate bipolar transistors, a small film capacitor, and input/output LC filters. The converter can provide discrete noninverting buck (NIBu) and boost (NIBo) operations with voltage gains of D and 1/(1 – D ), respectively. Moreover, it provides symmetric noninverting buck–boost (NIBB) and inverting buck–boost (IBB) operations with voltage gains of D /(1 – D ) and – D /(1 – D ), respectively. It supplies both continuous input/output currents, and it is well suited for reactive loads. It is immune from the commutation problem, and thus, has enhanced the reliability. The various modes of operation of the proposed converter make it suitable for diverse applications, including the following: 1) application as a direct ac voltage regulator when operating in NIBu and NIBo modes; 2) IBB operation can be utilized along with NIBu/ NIBo or NIBB operation to compensate both voltage sag and swell, when used as dynamic voltage restorer; and 3) symmetric NIBB/IBB operations can provide step-changed frequency output, similar to the single-phase matrix converters, for applications as induction motor drive or high-gain ac–dc rectifier. Extensive circuit analysis, component design guidelines, and appropriate comparisons are provided, followed by experimental results obtained using a laboratory prototype.

Novel Transformerless Buck–Boost Inverters Without Leakage Current

Abstract: This article presents novel transformerless single-stage buck-boost inverters with reactive power flow capability. The common-mode voltage of the proposed inverters is constant, which results in negligible leakage current. The output current of the proposed inverters is continuous that lowers the output harmonics and size of the output filtering capacitor. In the proposed inverters, only two switches receive high-frequency switching signals at a time, which reduces the power loss. The proposed topologies can achieve efficient power conversion with a wide input voltage range. A 120-Vrms/60-Hz output voltage, 74–200-V input voltage, and 500-W output power hardware prototype of the proposed inverter is built and tested with resistive, partially inductive, and partially capacitive loads. A peak efficiency of 97.3% is obtained.