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The classic boost and buck cascaded converter has inductors at the input and output ports of the converters, which makes it ideal interface for bidirectional battery charging applications where accurate current control and low ripple currents are required. This paper proposes a split duty cycle coupled multi-phase variant applied to the cascaded boost-buck converter and utilizing coupled inductor features to achieve very lower current ripples at the output,lower power losses, reduction in magnetic component volume. Moreover, current sharing between each phase is inherently implemented, making it suitable for high conversion ratio bidirectional operation in a systematic energy storage applications where the low voltage port has very high current. The paper covers split duty cycle converter operation principle using coupled inductors between input and the multi-phase output. Magnetic component design and selection guidelines are presented. The proposed control method and coupled inductor structure are validated by simulation and experimental results.

This work deals with the design and implementation of a new interleaved Luo power factor preregulator (PFP)-based electric vehicle (EV) battery charger, which is suitable for low-cost and improved power quality (PQ)-based EV charging. By interleaving two Luo converter cells, the input current is divided between them, which provides reliable and efficient charging of the battery at high-power discontinuous conduction mode (DCM) operation. This reduces the switch conduction loss due to reduced device current stress and thus, the charger efficiency is improved. The interleaved Luo converter incorporates low input and output current ripple due to ripple cancellation. This charger operates in constant current mode up to certain battery state of charge (SOC). However, for higher SOC range, it maintains constant voltage charging using a flyback converter at the next stage. Two converters are designed in DCM to provide inbuilt zero current switching and circuit diodes show good reverse recovery. An inherent PF preregulation is obtained at input mains over a wide range of supply voltages as well as dc-link voltage. The total harmonic distortion of input current is obtained as per PQ regulations. Its prototype is built and tested to validate its improved performance over two-stage solutions.

This article proposes an optimization design procedure for the switching waveform considering a bus bar geometry. In this proposed procedure, three items—the surge voltage, damped oscillation, and switching loss—are evaluated to achieve user-defined design objectives for realizing the optimized switching waveform. This study targets a bus bar geometry for high-speed switching using wide band-gap devices; thus, parasitic parameters in the power converter are considered. The parasitic parameters, which are the inductance, capacitance, and ac resistance, of the bus bar are analyzed by finite element analysis because it should be discussed the frequency characteristics for realizing the optimum switching waveform. The experimentation is performed using buck converter circuits, rated at 400 V and 30 A. As a result, the surge voltage, damped oscillation, and switching loss are, respectively, reduced 13.2%, 49.7%, and 29.7% with respect to user-defined design objectives, simultaneously.

This article presents a buck converter with a large step-down voltage conversion ratio, reduced ripple in inductor current and low semiconductor voltage stress. The proposed converter produces a lower output voltage at a sufficiently higher duty ratio compared to the conventional buck converter. The step-down voltage conversion ratio is modified by a series-parallel transition of two identical capacitors of a switch-capacitor cell. Two parallelly placed switches and two cross-connected identical capacitors are utilized to design the cell. An extra inductor is placed at the input side to oppose the sudden change in input current due to the series-parallel transition of the two identical capacitors. Therefore, two inductors are required to design the converter. These two inductors are coupled directly. The modified voltage conversion ratio reduces the ripple in inductor currents and output voltage. Direct coupling between the two inductors helps to further reduce the ripple in inductor currents and output voltage. The operating principle, analysis of ripple in inductor currents, and ripple in output voltage are discussed. The analysis of small-signal modeling is carried out and a voltage mode PI-controller is designed to enable the closed-loop operation. Finally, the proposed converter is implemented in hardware and the performance of the proposed converter is verified experimentally.

There is a requirement for a simple solution that provides seamless power management control and eliminates the issue of toggling between different operating modes in the stand-alone photovoltaic (PV) battery based hybrid system. The solution for the same is given in this article that uses a simple voltage control strategy. The given solution uses a voltage band technique for eliminating the toggling between charging and discharging modes. Further, the toggling between intermediate PV mode with charging and discharging mode is eliminated using the inner voltage band. Thus, the proposed control strategy provides a smooth and seamless control between different modes based on load voltage information. It avoids the overlap of charging and discharging modes within the switching cycle to improve the life-span of the battery. Also, the given control strategy does not require the power information and complex computations like division, etc., for its operation. The given solution can be easily implemented on any PV-battery-based hybrid system having independent control for charging and discharging of the battery with maximum power point tracking (MPPT). A simulation was done to verify the operation in various modes using seamless control. The simulation results are further justified with experimental results from the developed lab prototype.

The transient response control is one of the most important tasks in the control system design. The transient response has characterized based on the relationship between characteristic ratios and time domain specifications. The characteristic ratios are the design parameters of the characteristic ratio assignment (CRA) approach. This article presents a novel polynomial controller for all types of linear second-order systems. The proposed controller is designed using CRA. The important features of this controller are that it has simple design steps, set-point tracking, and disturbance rejection capabilities. Initially, the proposed controller is designed for an unstable nonminimum-phase second-order system to demonstrate the performance and robustness. Subsequently, the presented controller is analyzed and validated on the nonideal dc–dc buck converter. The buck converter is highly sensitive to the suddenly changing load conditions. The major issue of output voltage control in the dc–dc buck converter is addressed in this article. In addition, the robustness and performance of the proposed controller are verified for the sudden change in supply input voltage, the sudden change in the reference voltage, the parametric uncertainty in inductor ( $L$ ) and capacitor ( $C$ ), and the sudden change in load. Furthermore, the efficacy of the proposed controller is evaluated by comparing it with the recently published control schemes for this converter. The proposed controller is implemented using dSPACE 1104 real-time controller. Applicability of the presented controller is corroborated experimentally on the nonideal dc–dc buck converter. The simulation as well as hardware results recommend that the proposed controller is suited for the nonideal dc–dc buck converter under such conditions.

This article proposes a nonisolated wider step-down conversion ratio dc–dc converter having minimum phase behavior at nominal operating condition, for point-of-load applications. Compared to existing quadratic/stacked buck converter variants, the proposed topology shows effective switch utilization at low output voltages, lesser ripple content in source current, and reduced voltage/current stress on components. Time-domain analysis is formulated to anticipate the steady-state converter performance and establish design equations for L–C components. The state-space average model is derived and linearized transfer functions are evaluated to subsequently design a fixed-frequency sliding-mode controller. Step-by-step design procedure is presented to fulfil sliding surface existence, reachability, and stability conditions. Equivalent control law devised in this scheme is duly constituted from source side inductor current dynamics and load voltage error information, so it provides simple realization as well as better transient response. The distinctive features of proposed converter are studied analytically and demonstrated through experimental measurements on a laboratory prototype.

This article presents an online electrochemical impe-dance spectroscopy (EIS) technique for a Li-Ion battery. A frequency sweeping method and a precise impedance measurement algorithm are used for the proposed online EIS technique. The proposed algorithm consists of fast Fourier transformations, peak amplitudes, and phase difference estimations. Additional instrumentation with offset clipping and amplifying circuits expand the accuracy of the signal measurement. The offset clipping circuit increases the ripple to measurement voltage ratio without phase delay. The amplifying circuit gives more resolution for the ripple voltage. The proposed instrumentation ensures the precise measurement of ripple voltage and current. The proposed impedance measurement algorithm fulfills the precision level required for industrial Li-Ion battery. To validate the proposed approach, a 40-Ah 13.6 V Li-Ion battery charger was built using a synchronous buck converter and an Opal-RT based controller. The proposed spectroscopy technique will be useful to track and estimate internal electrochemical conditions of a battery.

With the significant reduction in board space occupied by the smaller GaN transistors, topologies that require a greater number of active devices as a tradeoff for reduced passive size, the main barrier to higher power density, have become attractive. Switched capacitor multilevel converters are good examples of topologies that can effectively reduce or eliminate passive components. Two GaN-based proof-of-concept designs, based on the three-level buck converter, one for a low-voltage (LV) 48-V server application and the other as a candidate for a higher voltage (HV) 400-V power factor correction circuit application, are discussed in this article. As a result of using lower figure-of-merit devices, significant efficiency gains are observed for the LV and HV converters developed in this article compared to a two-level topology. Smaller passive size (mainly inductors) also provides a significant increase in power density for the LV converter. A startup scheme is discussed, which eliminates the need for extraneous control loops or high-voltage-rated devices for the top switch. Finally, the thermal benefit of the three-level converter is demonstrated when compared to a two-level system for the 48-V server application.

Gallium nitride (GaN) high electron mobility transistor (HEMT) has a lateral device structure with wafer-level packaging, which is advantageous in minimizing parasitic parameters and overall device size. This type of packaging also has better thermal performance than conventional packaging due to low junction-to-bottom thermal resistances. It indicates copper layers in printed circuit boards can effectively serve as heat dissipation channels for the switching devices. When these copper traces and pours in the vicinity of the switching devices are carefully designed and shaped, they can also be utilized as an integrated output filter. In this article, a synchronous buck converter with a single-turn air-core integrated planar inductor is proposed to achieve both zero-voltage switching and high thermal performance of the GaN HEMTs. A new planar inductor design flowchart is introduced, and analytically estimated inductance and resistance are verified with simulation and experiment. Three different inductors are designed and fabricated to prove the improved thermal performance of the proposed converters.

Achieving high-efficiency power conversion with high power density for a large conversion ratio is crucially needed yet challenging in point-of-load applications because of increasing demands of loads. This article presents a new hybrid converter to address this need. The converter uses two interleaved inductors for complete soft charging of flying capacitors to provide high output currents with no capacitor hard-charge loss. This dual inductor hybrid (DIH) converter features a smaller number of switches and more effective switch utilization than a recently reported hybrid Dickson converter, yielding substantially less switch losses represented by smaller volt–ampere products and smaller equivalent output resistance. Converter operation principle is analyzed in detail to confirm the feasibility and benefits, and design considerations are provided to identify a practical design process. Experimental results verify the converter's operation principles and advantages with a 300-kHz 20-W prototype achieving 95.02% peak efficiency and 225-W/in3 power density. The converter's advantages and performance make the point-of-load converter architecture a good candidate for demanding applications, such as in data centers, telecommunications, and high-performance digital systems.

This paper presents the design, fabrication, and characterization on silicon integrated magnetics for high-frequency power applications. The presented device achieves superior characteristics in terms of energy density, electrical resistance, current capability, and inductance versus frequency stability. In order to demonstrate the effectiveness of use of the presented device for high-frequency power applications, it is tested with two different buck point of load (PoL) dc–dc converters, one of them is off-shelf chipset and the other is designed specifically for the microdevice. Experimental measurements show that the microdevices achieve a maximum inductance of about 50 nH, electrical resistance of 300 mΩ, rated current capabilities up to 1 A, and stable L versus f characteristics up to 100 MHz. Also, the PoL buck converters with the microdevices achieve a peak efficiency of up to 82% with a flat efficiency curve at switching frequencies up to 30 MHz while providing tight output voltage regulation (

IEEE Applied Power Electronics Conference and Exposition (APEC) (33th, 2018, San Antonio, Texas), This work has been supported by Asturias regional government under research grants GRUPIN14-076 and Severo Ochoa PA-17-PF-BP16151.

This paper presents an isolated auxiliary power supply for medium-voltage power electronics systems. The proposed converter comprises two stages: a non-isolated ac/dc stage that connects directly to the medium-voltage line, and an isolated dc/dc stage that provides 100-W output power at 24 V, with 10 kV isolation. The proposed modular ac/dc stage uses just one active semiconductor device per module, features an internal capacitor voltage balancing, and achieves power factor correction by employing predictive current control. High switching frequency operation of both converter stages enable a reduction in system size and weight when compared to traditional low-frequency transformer-based approach. The proposed converter is simulated and its operation is validated experimentally on a 100-W prototype.

Recently, a flyback converter with universal serial bus power delivery (USB-PD) specification is widely used in low-power adaptor application. However, the wide output-voltage-range operation of USB-PD makes the stability issue of the flyback converter more severe. This paper provides a brief discussion of two stability improvement methods for the peak-current-mode-controlled flyback converter at variable frequency and completely interprets those detailed techniques. Simulation validates the performances of the two methods. Furthermore, a control circuit and a flyback converter are built for experimental validation of the two stability improvement methods. Finally, some comments are also summarized.

The importance of online system identification (SI) in power electronics is ever increasing. It enables the tracking of system parameters, which in turn can be used for online controller tuning. Hence, SI is a key element for improving a converter's dynamic performance, stability, reliability. In this paper, a novel state-space-based SI approach utilizing the step-adaptive approximate least squares estimation algorithm with observation matrix randomization is proposed. The presented concept yields an accurate state-space model of the converter while simultaneously achieving a fast convergence rate and low computational complexity. Consequently, the estimated state-space model is utilized to automatically tune a full state feedback controller. This results in an improved converter performance in terms of overshoots, undershoots, and settling times. The proposed concept is verified by a prototype system comprising a two-phase buck converter and a field-programmable gate array. The provided measurement results highlight the effectiveness and benefits of the presented method over the state-of-the-art algorithms, as well as $z$ -domain estimation. It is shown that the number of required estimation iterations is more than halved in comparison with the state-of-the-art parametric SI approaches, while accuracy is improved.

Multioutput converters with single input source are currently studied as an alternative to conventional dc–dc topologies in order to improve power density in low-power multiload applications. This paper reviews three different ways in which a boost topology can be customized to supply multiple outputs. The first way uses a charge-sharing approach using individual switches to distribute inductor energy to different capacitors. The second method of creating a multiport converter (MPC) combines two converters with similar front end to generate two outputs using only one controlled switch. Using this method, a boost converter can be combined with single–ended primary–inductor converter (SEPIC), Cuk, and current source converter topologies. The third method uses time multiplexing of switches to produce two regulated ports and is referred to as switched-boost action. This method uses relatively less number of switches and allows regulation and control of all the outputs. Practical utility of switched-boost action based MPC is reported in this paper. This switched-boost MPC is applied to a renewable power converter system to interface a solar panel, a battery, and home loads to produce a 12-V and a 48-V bus. The 12-V bus is interfaced to battery and capable of optimally charging the battery in constant current–constant voltage (CC-CV) mode. The converter is demonstrated to operate with solar panel as it supplies a 12-V battery and a 48-V load bus. When the solar power is not available, the converter automatically goes into a mode in which the 12-V battery supplies the loads on the 48-V bus.

This paper presents the operation principle and benefits of a novel power converter topology named three-level two-stage decoupled active neutral point clamped (3L-TDANPC) converter, which is implemented based on a hybrid utilization of silicon (Si) insulated gate bipolar transistors (IGBTs) and silicon carbide (SiC) metal–oxide semiconductor field-effect transistors ( mosfet s). The 3L-TDANPC converter can achieve high efficiency with limited number of SiC mosfet modules while keeping balanced loss distribution among the switching devices, which helps increase the converter power ratings. In addition, in this 3L-TDANPC converter, the SiC mosfet has a potential to ride through short-circuit fault because of the presence of Si IGBTs. The key challenges that are associated with system resonant current are investigated and the methods to damp such resonant current are proposed and explained in detail. The simulation and experimental results based on a 1-MW 3L-TDANPC converter prototype confirm the expected benefits of this proposed converter and the effectiveness of the proposed resonant current damping methods.

In this paper, a dc-ac buck converter is proposed as a grid-side converter in high voltage dc (HVdc) transmission systems for high-power renewable energy source grid integration. The proposed architecture consists of multimodules of half-bridge voltage source converters (HB-VSCs). The dc terminals of the HB-VSCs are connected in series across the entire dc link (i.e., capacitor tapped), whereas their ac outputs are connected to multiwinding transformers to provide the three-phase terminals for ac grid integration. The proposed grid-connected capacitor-tapped multimodule converter (CT-MC) architecture, inspired from the HVdc shunt tap proposed by ABB, provides a dc-ac conversion with a relatively moderate voltage rating of semiconductor devices. It also provides operation with a lower number of semiconductor devices, gate driver circuits, voltage sensors, and lower total MVA rating of semiconductor devices (67%) compared with the conventional three-phase HB modular multilevel converter, which positively affects the system cost and reduces the computational burden of the employed controller. In this paper, the operational concept and control of the CT-MC are presented along with a capacitor voltage balancing approach. Simulation results are presented during normal and abnormal conditions to show the viability of the proposed architecture. Finally, a scaled down prototype for the CT-MC is employed to validate the converter operation. This work was supported by the National Priorities Research Program (NPRP) from the Qatar National Research Fund (a member of Qatar Foundation) under Grant 9-092-2-045 Scopus

The paper proposes an optimal control strategy for the interleaved flyback based microinverter to improve its efficiency over the entire operating range. This control scheme is based on the choice of an appropriate operating mode [1-converter discontinuous conduction mode (DCM), 1-converter boundary conduction mode (BCM), 2-converter DCM, and 2-converter BCM] at various instantaneous power magnitudes. The proposed control method reduces the fixed losses associated with the gate driver and the transformer at the low power level. It also reduces the switching losses that may result due to the extremely high-frequency operation of the BCM at the low power level. Additionally, it also reduces the conduction losses through low current peak due to BCM and equal current sharing between the two converters at the high power level. Switching losses, due to the low-frequency operation of the BCM at a high power level, are also reduced. Operating mode selection of the interleaved inverter at a particular power level is based on the information of optimal efficiency. Detailed calculations of peak current references have been carried out for the various operating modes of the interleaved flyback based microinverter. Simulation and experimental results have validated that the proposed control method results in better efficiency compared with the conventional (DCM, hybrid DCM/BCM, hybrid 1-converter/2-converter) control methods with the output current total harmonic distortion remaining within the specified limits.

This work proposes a light-emitting diode (LED) luminaire for street lighting based on modular drivers. Each module consists of a driver composed by two integrated dc–dc converters. The first one is a buck–boost converter responsible for the power factor correction, and the second is a buck converter that controls the load current. Both of the converters operate in the discontinuous conduction mode of current. In order to make the system robust against failure, each driver supplies an independent set of power LEDs. Thus, in case of failure of one or more drivers, the system is not completely compromised. The design of the electronic drivers is presented. Experimental results of a prototype with rated power of 50 W (two modules of 25 W) are performed in order to show the feasibility of the proposed solution.

This paper proposes a current sensor embedded in a laminated bus bar. The proposed sensor is based on the Rogowski coil principle; the sensor can detect the magnetic flux corresponding to a derivative waveform of the current in a laminated bus bar. The electrical stray elements of the sensor depend on its geometry. The magnetic flux generated by the bus bar depends on the current repartition which is a function of the equivalent frequency during current transients. Both phenomena are discussed using partial element equivalent circuit-based software. Thanks to these investigations, the sensor is designed to measure switching waveforms. It is confirmed that the verification of the proposed current sensor embedded in a laminated bus bar can perform the measurement of a switching waveform using a buck converter circuit rated at 50 V and 8 A.

A new isolated current-fed zero-current switched (ZCS) front-end dc/dc converter based multilevel inverter is proposed for multi-input applications. The proposed front-end converter with only two controllable switches integrates two different renewable energy sources, resulting in an advantageous compact structure and low conduction losses. The ZCS turn- off is achieved in both the controllable switches with the proposed modulation scheme. The converter maintains ZCS turn- off under a wide load, as well as input voltage variations by employing frequency modulation along with a variable duty ratio technique. Simple structure, soft switching, high gain, and automatic load regulation make the converter structure novel for simultaneous power management in multi-input renewable energy applications. Converter operation and design guidelines have been outlined. A laboratory prototype of the proposed converter is developed and tested at 300-W power level. Simulations and experimental results demonstrate the robust performance of the converter under load, as well as input source voltage variations.

Energy storage devices are essential to provide voltage and frequency stability in renewable energy sources, such as solar and wind. Due to operational requirements of distributed generation systems, energy storage devices like batteries and supercapacitors need bidirectional dc-dc converters to allow charge or discharge exchange according with the necessary conditions. In this paper, a new nonisolated bidirectional quadratic converter characterized by high voltage gain in both step-down (Buck) and step-up (Boost) operation modes is proposed. In addition to the wide conversion range, it presents continuous input and output current and reduced charging/discharging ripple. All these features allow an optimized operation between the dc bus and storage devices. The operation principle of the proposed converter in both condition modes (step-down and step-up), the converter design, as well as the theoretical analysis in different conditions will be discussed. Finally, the performance of the proposed converter is confirmed through simulation and experimental results. info:eu-repo/semantics/publishedVersion

A two-stage quasi-resonant LED driver with a digital control method is proposed in this paper. The first stage of this converter is a boost circuit with a power factor correction function, and the second stage is a dual-buck circuit that works in a quasi-resonant zero voltage switching state. Because of the soft-switching characteristics of the converter, switching losses are reduced and efficiency is significantly improved. A digital control method is adopted to detect the peak value of inductor current and enhance system reliability. Moreover, because LEDs are always driven by a current source, a current loop is designed to maintain constant output current. IRS2104 is chosen as the drive chip and the microcontroller is AT90PWM216, which can improve the quality of the drive signals. The output of the converter is a square wave that drives two branches of antiparallel LEDs. A 60-W prototype was designed to demonstrate the theoretical analysis. The obtained power factor was as high as 0.987 and the efficiency reached 92.3%.

A conventional Flyback converter's controller is based on the primary side of the coupled inductor–requiring isolated coupling for both the output voltage measurement and for any synchronous rectification gate signal. A novel communication approach is proposed here, whereby the need for such signal coupling is eliminated by moving the controller to the secondary side and communicating back to the primary switch through the coupled inductor itself. This simultaneously allows direct access to the output voltage, reduced component count, synchronous rectification, and soft primary switch turn-on without optoisolator propagation delay or additional magnetic coupling. This paper presents a novel drain–source voltage sensing method that provides reliable turn-on signals for the primary switch along with the principles of the secondary-side control. Concept feasibility is proven using a 65 W demonstrator with a simple constant-on-time control scheme. The benefits, limitations, and suggested improvements are presented.

A novel hybrid five-level voltage source converter for high-efficiency applications is investigated in this paper. Compared with traditional multilevel converters, this hybrid multilevel converter generates desired staircase voltage levels with a reduced number of power devices and isolated drivers at higher voltage levels. It has redundant switching state combinations in hybrid multilevel converter, which makes it easy to balance flying capacitor voltages and realize fault-tolerant operation. A voltage balancing control strategy based on switching state redundancies is presented for the hybrid multilevel converter, to generate desired levels and also keep voltage balance of flying capacitors at the same time. The performance of the hybrid multilevel converter under various operating conditions is investigated in MATLAB/Simulink. The effectiveness of the proposed hybrid multilevel converter is validated by experiment results.

This paper presents an improved efficiency impedance control network (ICN) resonant dc–dc converter that maintains zero-voltage switching (ZVS) and near-zero-current switching (ZCS) across wide ranges in input and output voltages and output power. The improvement in efficiency in this burst mode operated converter is achieved through an optimized startup control that minimizes its startup transient and helps the converter maintain ZVS and near-ZCS operation, even during the startup for each burst cycle. This optimization of startup is made possible by a new accurate time domain model for the ICN converter waveforms that helps reduce the number of non-ZVS transitions by 75%. A prototype 200 W, 500 kHz ICN resonant converter designed to operate over an input voltage range of 25–40 V and output voltage range of 250–400 V is built and tested. The prototype ICN converter achieves a peak efficiency of 97.2% and maintains greater than 96.2% full power efficiency at 250 V output voltage across the nearly 2:1 input voltage range, and maintains full power efficiency above 94.6% across its full input and output voltage range. The converter also maintains efficiency above 93.6% over a 10:1 output power range across its full input and output voltage range.

In this paper for power factor correction (PFC), a modified Landsman converter is introduced. The application is targeted for high-brightness (HB) projection application with brightness control for HB red–green–blue (HB-RGB) light-emitting diode (LED). A pulse-width modulation (PWM) technique is used for intensity control to achieve brightness control of the LED driver. The proposed PFC converter is used to feed a dual output flyback dc–dc converter that supplies power to the forced cooling unit and the LED module with galvanic isolation. The brightness control of LED is performed by synchronous buck converter. The modified Landsman converter operates in discontinuous output inductor current mode for PFC at universal ac mains. A prototype of the proposed LED driver is experimentally verified. The performance of proposed driver is evaluated at full and light-load condition for universal ac mains (90–265 V) over a full range of brightness. The power quality parameters are found within the acceptable limits of harmonic standard IEC 61000-3-2 for universal ac mains.

This paper proposes a dual-input central capacitor dc/dc converter for distributed photovoltaic (PV) power harnessing, which can be used to boost dual input sources with minimized semiconductor voltage/current stress and converter rating. Also the proposed circuit could realize the independent maximum power point tracking capability for two input PV sources. This paper analyzes the operational principle of the proposed dual-input central capacitor dc/dc converter under both continuous conduction mode and discontinuous conduction mode and presents a comparative study between dual-input central capacitor converter and its counterparts. Besides, an adaptive control method considering PV power difference, operational safety and efficiency is elaborated. Finally, the proposed converter along with its adaptive control method was verified through matlab simulation and a laboratory prototype.

This paper presents the flexible dc capacitor voltages balancing control method for star-connected cascaded H-bridge converters. In this paper, the power flows are analyzed by investigating all the converter's control freedoms. Based on the analyses, users can accomplish the dc capacitor voltage balancing with both negative-sequence current and zero-sequence voltage. These two kinds of control options are further integrated together with the defined weighting factor $K$ . The low-voltage ride-through operation of a proposed control method is also discussed in this paper. The control method is verified with a 220-V 1-kVA static synchronous compensators based on the star-connected cascaded H-bridge converters, and the experimental test results show that all the dc voltages are well regulated at the commanded value with different weighting factor $K$ .

Current sharing controller/functionality is commonly utilized for multiphase converters to achieve current balancing between converter phases. Conventional current sharing control schemes generally require sensing the current of each phase, leading to increased size and cost in addition to issues associated with current sensing inaccuracies. A sensorless current sharing control scheme is proposed in this paper that utilizes the difference between the input capacitor voltage ripple values to indicate the phases' current distribution status. The duty-cycle value of each phase is autotuned in a way to minimize the difference between the input capacitor voltage ripple values based on a single voltage sensing point, which results in equal current sharing with no need for current sensing. In addition, the input capacitor voltage ripple sensing does not need to be very accurate, and the sinusoidal frequency component of interest of the ripple is obtained by using a low-cost bandpass filter for improved ripple sensing resolution and noise immunity. Experimental results obtained from a digitally controlled two-phase synchronous buck converter prototype are presented to validate the feasibility of the proposed concept.

In this paper, we propose a 500-MHz on -chip digitally controlled buck converter in which active and passive components are fully integrated on a single CMOS chip. To achieve high-power density, a two-phase interleaving buck converter with negatively coupled inductors is adopted to reduce the silicon area for both inductors and output capacitors. In addition, the proposed on -chip stacked L/C structure can achieve 20% area-saving. Furthermore, to support a 500-Hz switching frequency, we present a low-power digital pulsewidth modulation (PWM) controller that includes a 9-bit time-based analog-to-digital converter and a 15%–90% wide-range digital pulsewidth modulator (DPWM), which occupies only $0.075 \text{ mm}^{2}$ and dissipation of 3 mW. The prototype IC fabricated in 65-nm CMOS can convert a 2.2-V input to a 1.2-V output and achieve a peak power efficiency of 76.2% and maximum power density of $0.76\ {\rm W/mm}^{2}$ . Simultaneously, it can deliver 0.84 W and occupy $1.1 \text{ mm}^{2}$ of effective area that includes a pair of 1.54-nH on -chip inductors and 2.63-nF on -chip capacitors.

This paper presents an energy-efficient buck-type capacitor charger integrated circuit (IC) that can deliver high instantaneous power from a low-capacity battery using a capacitor as an energy buffer. The prototype IC, which was designed and fabricated in 250-nm CMOS, reduces capacitor charging losses by driving the buck converter with gradually increasing pulsewidths and then recycles the remaining energy by operating the buck converter in the reverse direction. The presented digital pulsewidth modulator (DPWM) supports a wide range of duty cycles from 4% to 96% with a fine resolution of 0.36% and a high switching frequency of 1.5 MHz. The optimal switching frequency and transition time that can minimize the charging/discharging losses are analyzed. The prototype charger IC can charge a $10\text{-}\upmu{\rm F}$ capacitor to 4.2 V with a transition time of 1.25 ms with a peak charging efficiency of 93% while operating at a 1.5-MHz switching frequency.

In this paper, an electric vehicle (EV) battery charger with interleaved Landsman converter (ILC) followed by a flyback converter, is designed and evaluated for improved power quality (PQ) charging of battery. A built-in wave-shaping is obtained at the charger front-end due to improved PQ characteristics of ILC. This PFC converter consists of two Landsman converter cells, which are designed in discontinuous conduction mode (DCM) to share the input and output currents. The current sharing at input results into lower input current ripple as well as peak current stress through the switch, is reduced. This, further improves the input current harmonics profile. Moreover, the reduced output voltage ripple gives reduced rms current in the output capacitor. A phase shift PWM scheme (PSPWM) is used for ILC and the duty cycle for the switches is selected below 50%. This allows the ripple cancellation at line and load sides. The interleaving at PFC stage as well as DCM based design ensures a low cost charging solution as compared to the conventional Landsman converter (CLC) based chargers in this power range. However, the flyback converter provides the current control during the charging of the battery in constant current (CC) and constant voltage (CV) regions. The harmonics spectrum of mains current follows the recommended PQ regulations over a range of varying line voltages and loadings.

The coupled inductor single-input dual-output (CI-SIDO) dc–dc converter is an alternative to multiple parallel dc–dc converters for applications requiring multiple regulated supplies. CI-SIDO exhibits the merits of reduced ripple, small volume, and high efficiency. However, the coupling of inductor currents results in coupled outputs leading to cross-coupling and cross-regulation problems. Due to cross-coupling of the output voltages, the compensator design becomes complex. This article proposes a decoupled voltage-mode control to address the issue of cross-coupling of output voltages. It also demonstrates the stability boundary for controller design. The proposed controller is designed using simple analog Type-II compensator. A systematic compensator design procedure is also developed. The proposed controller decouples the output voltages, ensures good stability margin as well as good load regulations and audio-susceptibility. The design is verified through simulation and experiments. The experimental results shows that the decoupled control significantly suppresses the cross-regulation with fast transient response speed for the load, input, and reference variation. A transient performance comparison of proposed decoupled voltage-mode control for the CI-SIDO buck converter with state-of-art control methods for the single-inductor SIDO buck converter is also presented.

The existing chargers for electric vehicles (EVs) use rugged nonlinear diode bridge rectifier to avail dc voltage at the input of dc–dc converter, and introduce serious power quality issues in the input ac current. These issues set the formidable need to improve the power quality (PQ) performance of existing battery chargers by eliminating the input bridge. This is achieved in this work, by the addition of an improved PQ based bridgeless (BL) Luo converter. This power factor correction (PFC) converter is the combination of two Luo converters, which operate independently in the respective half cycles, with common input inductor. The converter provides low cost and high power density based EV charging solution as fewer number of components conduct over single switching cycle due to elimination of input diode bridge in the conventional PFC converter. The charger input current is made to follow the source voltage, exactly in phase and high input power factor is achieved. Moreover, the source current total harmonic distortion is reduced below 5% as per the IEC 61000-3-2 standard under steady state and during sudden variations at load and line side.

The conventional step-down dc–dc converters under the single pulsewidth modulation (PWM) control scheme may not provide enough step-down voltage conversion capabilities with considering the minimum on -time and the switching frequency of the power switch. In order to overcome this difficulty, a dual PWM control scheme for designing the high step-down dc–dc converter is proposed in this article. Both high-frequency and low-frequency PWM waveform generators are utilized in synthesizing the dual PWM control of buck converters. The resulting PWM waveform will lead to various switching cycles, and five operating modes of the buck converter, which can be defined accordingly. The operation principle of the proposed converter and its small-signal switched model are presented in detail. One salient feature of the proposed design is that if the duty cycle of the high-frequency PWM is exactly equal to that of the low-frequency PWM, by exploring the volt–second balance condition, the voltage gain can be expressed as the quadratic formula of the duty cycle of the PWM signal when power switches are operated under the continuous conduction mode. Thus, a high step-down conversion ratio and significant reductions of the inductor current ripple can be ensured simultaneously. Since no modifications of the conventional circuit topology are made, the proposed scheme is very cost-effective. Simulation studies and hardware prototype circuit implementations are conducted to validate the proposed design with satisfactory performance.

This paper proposes a new isolated three-port bidirectional dc–dc converter for simultaneous power management of multiple energy sources. The proposed converter has the advantage of using the least number of switches and soft switching for the main switch, which is realized by using an inductor–capacitor–inductor ( $LCL$ ) -resonant circuit. The converter is capable of interfacing sources of different voltage–current characteristics with a load and/or a dc microgrid. The proposed converter is constructed for simultaneous power management of a photovoltaic (PV) panel, a rechargeable battery, and a load. Simulation and experimental results show that the proposed converter is capable of maximum power point tracking control for the PV panel, when there is solar radiation, and controlling the charge and discharge of the battery, when there is surplus energy and power deficiency with respect to the load, respectively.

A new prototype of a zero voltage soft-switching (ZVS) utility frequency ac (UFAC) to high-frequency ac (HFAC) resonant power converter for induction heating (IH) applications is presented in this paper. The series resonant ac-ac converter proposed herein can process the frequency conversion without any diode bridge rectifier (DBR), thereby reducing the relevant conduction power losses. In addition, power factor correction (PFC) can be naturally achieved by the inductor-based boost half-bridge(BHB) circuit with the non-smoothed dc (NSDC)-link. The operation principle together with a IH load power regulation scheme is described, and the converter performances including ZVS operations and PFC are demonstrated in an experiment with a 3.0kW–30 kHz prototype by comparing with the previously developed converter. Finally, the feasibility of the proposed ac-ac converter is evaluated from a practical point of view.