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A multi-level boost topology based on a flying capacitor is compared in this work with the hybrid, multi-level, partial power processing topology already presented in the literature for use as a highly efficient and compact dc/dc stage in 1500-V, two-stage, grid-connected PV systems. Different variations of the resonant stage of the hybrid topology are analyzed and compared in terms of losses, volume and complexity. Full multivariable optimization is conducted for the multi-level boost topology with different number of levels and for all the analyzed variations of the resonant stage of the hybrid topology. Appropriately rated new classes of 650-V and 900-V WBG devices are included in the optimization algorithm. It is concluded that due to the dominant conduction losses and gap in the voltage rating of the commercially available WBG devices between 650V and 200V, increase of the number of levels over 4 leads to the deteriorated loss and volume performances. All the analysis related to the resonant stage of the hybrid topology is confirmed by detailed and comprehensive measurements of two prototypes of 4kW of nominal and 7kW of maximal power. Additionally, all the loss models applied in the optimization algorithms presented in this paper are confirmed by detailed measurements, thermal calibration and finite element thermal simulations of the wide bandgap devices and inductor designs employed in this work. [ABSTRACT FROM AUTHOR]

This article aims at developing a multigene symbolic regression model of interfacial tension (IFT) for determining the health index of insulating oil. The oil parameters considered for modeling of IFT are break down voltage, resistivity, acidity, tan delta and water. The unique study undertaken in this article attempts to develop a multigene symbolic regression model for generating and evaluating the relationship between IFT and other oil parameters. Data utilized in this study involves actual oil testing parameters of in-service transformers and reactors of age more than 15 years. A sensitivity analysis has been carried out to investigate the relative contribution of input variables to the model output. The result of sensitivity analysis has further been used to determine the weight of parameters for calculating the health index of insulating oil. Finally, the health index of 400 in-service transformer and reactors are evaluated and analyzed. This research will help in undertaking decisions for the replacement of oil based on health index, thereby increasing the life span of transformer and reactors. The health index so obtained will act as a reference for planning necessary maintenance activities of the equipment and thereby saving unprecedented failure of the oil-filled transformer and reactors. [ABSTRACT FROM AUTHOR]

This article aims at developing a gradient boosting (GB) model with parameters optimized by the Bayesian optimization (BO) method for detecting various types of fault in an oil-immersed transformer and reactor. The developed model depicts higher accuracy in comparison with other machine learning (ML) techniques, such as XGBoost, AdaBoost, random forest, and support vector machine parameters being optimized by BO. A comparison of the skill score depicts the superiority of the developed Bayesian optimization-based gradient boosting (BO-GB) model with respect to Bayesian optimized other ML techniques. Further comparison of the model with conventional Duval pentagon verifies the accuracy of detecting the faults, which were missed by the former. Also, the software has been developed based on the proposed BO-GB method for the on-site detection of the fault. In addition, actual values of dissolved gases with respect to fault confirmed after the internal inspection of the transformer and reactor are tabulated and compared. The data so presented will help in utilizing the authentic dissolved gas data in addition to the already available IEC TC10 databases for future works. The study undertaken in this article will help utilities in diagnosing the incipient faults more accurately and precisely, thereby preventing hazardous operating conditions along with minimizing the downtime cost. [ABSTRACT FROM AUTHOR]

High-frequency converters with high power density have shown promise in recent years. Air-core planar inductors built with printed circuit boards can eliminate problems associated with the use of magnetic materials, such as iron loss and magnetic saturation. However, conventional air-core planar inductors suffer from eddy current loss. Eddy currents affect the resistance and inductance of the inductor. This article proposes a stranded wire structure to reduce eddy currents more than that in the conventional spiral wire structure. Eddy currents can be reduced by splitting the windings as well as currents of each split winding are balanced in the proposed structure. Seven types of air-core planar inductors were built, and their resistances, inductances, and impedances were measured to evaluate the effects of different structures on eddy currents. Furthermore, the temperature distribution of the planar inductors was measured while supplying a sinusoidal voltage with a power amplifier. The experimental results demonstrate the usefulness of the proposed stranded wire structure. Furthermore, the experimental result shows that the stray capacitance of the inductor can be reduced as a by-product of the proposed stranded wire structure. [ABSTRACT FROM AUTHOR]

This article investigates the functional link neural network assisted deadbeat predictive current control for an onboard charger (OBC) of an e-rickshaw with multistep charging capability. This control algorithm is presented for wide load operation of OBC since a multistep charging scheme is introduced to reduce the electricity consumption by OBC in the course of the peak load hours. The presented grid-connected OBC topology has two stages interconnected with the dc link capacitor. The first stage is a front-end converter to regulate the voltage at the dc link capacitor. Moreover, it regulates the power quality within the IEEE-519 standard. Furthermore, a dc–dc converter to regulate the charging current is the second stage of the OBC. Keeping this in view, a bidirectional interleaved isolated single ended primary inductor converter (SEPIC) converter topology is utilized. To analyze the performance of the OBC under distinct operating conditions such as grid voltage variations, an experimental prototype of the bidirectional OBC, is developed. Furthermore, the efficacy of the bidirectional operation of the designed system is analyzed through the vehicle to grid operation. [ABSTRACT FROM AUTHOR]

Unlike VSIs, the single-stage inverters (SSIs) from the family of Z-converters are capable of boosting input dc to a desired ac voltage. The Z-network of these converters consists of a symmetric X-shaped network or a combination of inductors and capacitors. The basic Z-source converter (ZSC), connected in X-shaped fashion is modeled as a fourth-order system. This can be further modeled as a second-order system to reduce the sensor count but this may lead to an unstable system if there is an asymmetry in network parameters. Also, the source current of SSIs contains second-order ripple current (SRC) component, which oscillates at twice the supply frequency and has detrimental effects on sources. To alleviate the above problems, a parametric uncertainty compensation and ripple mitigation (PUCRM) control methodology is proposed. PUCRM control can be used to maintain stability and achieve desired performance during parametric uncertainties in the dc–dc stage and to reduce SRC propagating to the sources while feeding ac loads. PUCRM consists of a nominal dual-loop PI controller, which regulates the SSIs to achieve desired performance and a nonlinear integral sliding mode component that mitigates the uncertainties and ripple component. The proposed method is verified using simulation and experimentation. [ABSTRACT FROM AUTHOR]

A 1 MHz active-clamp flyback converter for solar street-lighting applications, featuring a partial power processing, is proposed in this article. The secondary-side resonance between the output capacitor and transformer leakage inductor is utilized to reduce rms current and conduction losses. In comparison with the traditional light-emitting diode drivers based on full power converters (FPCs), the proposed approach that uses partial power converters (PPCs) can significantly improve the overall system efficiency by eliminating the redundant power handling process. The universal schemes are discussed and the optimal solution is eventually determined by the partial power ratio. The advantages of PPC compared with FPC in device stress, losses, and regulation capability are demonstrated by simulation. With GaN devices, a 100 W/1 MHz prototype was built to verify the analysis. The experimental results show that the proposed topology can reduce the power rating of the converter by up to about 80% while increasing the system efficiency by up to 95.8%. [ABSTRACT FROM AUTHOR]

In this article, a multioutput-based transformerless hybrid solar inverter (TLHSI) with no right half-plane zero (RHPZ) and reduced common-mode leakage/ground current is presented for photovoltaic (PV) based microgrid applications. In the proposed multioutput TLHSI, two magnetically coupled inductor coils are placed between the input and dc output sides along with a dc-link capacitor to continuously provide the stored energy to the dc load so that the RHPZ is eliminated and, thus, makes it a minimum phase system. Furthermore, a hybrid unipolar sinusoidal pulsewidth modulation technique is established to nullify the high-frequency components of common-mode voltage across the PV to ground stray capacitor. Also, it normalizes both dc and ac loads at the same instant from a single dc input during each operating state of the proposed TLHSI. The shoot-through issue is resolved in the proposed TLHSI, which increases the system reliability. Furthermore, as the deadtime is not required in between the switching pulses, the quality of the inverter output voltage improves. The performance analysis of the proposed TLHSI is compared with the existing topologies. To validate the performance of TLHSI, a scaled down 340 W laboratory prototype is developed. [ABSTRACT FROM AUTHOR]

In this article, an improved soft-switching quadratic boost converter is proposed. Instead of inserting an additional active clamp or auxiliary zero-voltage transition circuit at the switching node, the proposed topology connects the high-voltage switching node to the input diode node by replacing one of the input diodes with a low-rated switch. The proposed topology can attain soft-switching condition for all the switches and input diode turns-off under zero-current switching (ZCS). The operation of input-side switch not only aids zero-voltage switching (ZVS) turn-on for the main switch but also helps in reducing the conduction loss. Also, the input-side switch operates under ZCS turn-on and ZVS turn-off, making it a loss economical solution. An adaptive timing scheme for driving the input switch is proposed, which can ensure soft-switching condition under varying gain and load range. The detailed operational modes, analysis, and design considerations of the proposed topology are presented. A 250 W hardware prototype is built to validate the performance of the proposed converter operating at 100 kHz switching frequency. Results with adaptive soft-switching scheme shows that the converter is modulated to achieve its best efficiency condition under various system conditions. A peak efficiency of 96.1% at 155 W and efficiencies above 95.75% over a wide load range are achieved using all Si devices. [ABSTRACT FROM AUTHOR]

Global electricity generation by renewable energy sources and the electrification of the transportation system are gaining more importance to mitigate climate change. The dc system plays a significant role in these developments. To protect dc systems, dc circuit breakers with advanced technology are required that are fast and reliable. Various solid-state dc circuit breakers, such as $Z$ -source and $T$ -source circuit breakers, have been presented in the literature to meet the dc system demand; however, these topologies suffer from limitations such as high conduction loss, complexity in design, no physical isolation, and presence of negative current flow in load during reclosing. To overcome the aforementioned limitations, a bidirectional solid-state dc circuit breaker (BD-SSCB) that detects the overload or short-circuit faults and responds instantaneously to mitigate the fault current has been proposed in this article. The controllable shutoff function is much needed in applications where sudden load change occurs continuously during the normal operation, such as varying acceleration of an electric vehicle. The proposed BD-SSCB is validated using spice simulations and hardware experiments with varying system parameters for a system rating of 400 V/10 A. [ABSTRACT FROM AUTHOR]

In this article, a hybrid wireless power transfer system, which combines induction heating (IH) and inductive power transfer functionalities, is proposed to improve the performance of a domestic IH application with small loads weakly coupled to distant inductors. Considering the basic single-inductor domestic IH application, the proposed system adds a secondary inductor with a series compensation capacitor directly attached to the small ferromagnetic cookware. The extended distance can be used to implement the glassless induction concept, where the ceramic glass of typical cooktops is substituted by the kitchen surface itself. The design of the secondary coil is carried out by means of a combination of finite-element and electrical simulations. A design process, including the housing of the resonant capacitors and the selection of the secondary winding number of turns and cabling, is presented. As a result, a prototype is implemented and tested under working conditions up to 1500 W at several distances. Experimental results validate the electrical modeling and simulation. Moreover, thermal results confirm the feasibility of the proposal and validate the adopted strategies for the capacitor housing. [ABSTRACT FROM AUTHOR]

Three-phase (3-φ) induction motor drives operated with switched capacitor (SC) inverter circuits offer superior harmonic performance and voltage boosting. The SC network, however, generally requires additional circuitry to precharge the capacitor(s) to prevent inrush current. To obviate the requirement of the extra circuit, an innovative SC precharging scheme is presented, which utilizes the winding inductance of the motor. The inverter circuit is so operated that the motor winding inductance first stores electrical energy from the input dc source and then releases it to the SC. These two actions are continued till the SC is precharged to a voltage equal to the magnitude of the input dc source. The circuit operation during the precharging is similar to the operation of a conventional buck-boost type dc–dc converter. The precharging action is so designed that the voltage of the SC cannot increase further. Therefore, the proposed scheme does not need any voltage sensor. The operation of the circuit during precharging is analyzed extensively to develop a mathematical background for the given method. It is shown that by manipulating the switching frequency during the precharging the precharging time can be controlled as per the user requirements. Various claims are validated using computer simulations and experiments. All the results are presented. [ABSTRACT FROM AUTHOR]

Several exhaust gas regulations are being implemented to prevent the hazardous emissions of volatile organic compounds (VOCs) and particulate matter (PM) from paint and print factories. The VOCs generate photochemical oxidants and suspended PM, such as PM2.5, which has become a global environmental problem. We evaluate the catalytic nonthermal plasma (NTP) technique for controlling the emission of VOCs. The article proposes a wet-type catalysis plasma reactor to extend the treatment of water-soluble VOCs. Initial evaluation of the proposed technique involves simultaneous removal of nanoparticles along with individual VOCs, toluene, acetaldehyde, acetic acid, and ammonia, at a relatively high gas flow rate of 10 L/min. Further, pellets of α-alumina and TiO2 spheres are employed in the NTP reactors for assessing their catalytic performance. We install an MnO2 catalytic reactor downstream of the plasma reactor for ozone removal. Simultaneous treatment of typical VOCs and nanoparticles using dry and wet-type catalytic NTP reactors shows that the wet-type reactor has superior average particle collection efficiency of 100%. However, the dry-type NTP with α-alumina shows a higher toluene removal efficiency of 91% compared to 73% in the wet type. Further, the respective removal efficiencies for acetaldehyde, acetic acid, and ammonia are 100%, 100%, and 95%. Notably, the toluene removal efficiency drops to 65% with the TiO2 catalyst. [ABSTRACT FROM AUTHOR]

The nonminimum-phase property of the dc–dc boost converter can create difficulties in designing a stable, robust, and fast control for the output voltage. In this article, these difficulties are reduced by modifying the state model of the boost converter in such a way that it behaves like a minimum-phase system. More specifically, the control input entering the state equation for the output voltage is treated as an unknown disturbance to make the relative degree of the system equal the system’s order. As a result, the modified model does not exhibit zero dynamics, so that it can be treated as a minimum-phase system for the control design. The modified model is, then, used to derive a dynamic compensator for the output voltage regulation. More explicitly, the dynamic compensator is designed based on combining linearizing feedback control with a disturbance observer. The latter is employed to compensate for model uncertainties and unknown load with a view to ensure asymptotic regulation under the composite controller. The asymptotic regulation is achieved due to the integral action property characterizing the disturbance observer. More interestingly, after simple algebraic manipulation, it turns out that the composite controller reduces to a dynamic state feedback control plus an antiwindup scheme to mitigate the effect of control saturation during transients. The performance of the proposed controller is verified by experimental tests. The experimental results demonstrate the ability of the proposed controller to achieve good transient and steady-state performances. [ABSTRACT FROM AUTHOR]

Maximum power point tracking (MPPT) plays a significant role in a photovoltaic (PV) system's optimal performance. Bypass diodes create multiple peaks on the power–voltage curve during partial shading conditions (PSCs), reducing the PVs overall power extraction capability. This article proposed a new hybridized architecture for switched inductor and switched capacitor circuit based voltage equalizer (VE) topology with reduced switch count to prevent the multiple peaks and increase the energy yield during PSCs. The proposed VE operates with a fixed duty cycle and frequency. The MPPT controller with PSC detection is also proposed to operate VE only when the PSC is detected to avoid unwanted switching and conduction losses. The proposed system's effectiveness for ten modules connected in series has been determined compared with other modular state-of-the-art VEs. The proposed topology can be extended with a smaller number of control switches. On average, the experimental results showed a 30.42% improvement in energy yield in comparison with the conventional systems. Furthermore, the proposed controller offers the MPPT efficiency of 99.28% with a tracking time of 0.10 s for uniform shaded conditions and 0.692 s for PSCs on average. [ABSTRACT FROM AUTHOR]

Three-phase variable speed drives play a key role in energy conversion systems. To comply with the electromagnetic compatibility standards for the 0–2 $\text{kHz}$ frequency range, magnetic chokes are typically placed at the dc or ac sides of the drive systems. Recently, compatibility levels have been defined at 9–150 $\text{kHz}$ for the public network in accordance with IEC 61000-2-2. At this frequency range, common-mode noise is an important factor affecting electromagnetic compatibility. This article analyzes the effect of choke placement on common-mode noise at the 9–150 $\text{kHz}$ frequency range. In particular, a comparative study on choosing either two dc-link choke inductors or three ac-line inductors is carried out via mathematical calculations. To this end, single-phase common-mode equivalent models are extracted for each placement of dc and ac chokes. Subsequently, by calculating the transfer functions of the currents in the single-phase equivalent circuits, the attenuation rate of common-mode currents from the motor to the grid side is analytically modeled for each choke configuration. The developed theories prove that ac-line inductors are more effective at suppressing low-frequency common-mode contents, while dc chokes are useful in attenuating high-order noise contents. Laboratory test results are used to prove the validity of the presented theoretical modeling and analysis. [ABSTRACT FROM AUTHOR]

A novel single-stage ac/dc isolated onboard charger with modular stacked switches structure utilizing interleaved control is proposed in this article for high-voltage (HV) battery systems in electric vehicles (EVs). In the proposed converter, modular interleaved bridgeless ac/dc boost converters are integrated with modular CLL resonant circuits through sharing the two legs of stacked switches. With this configuration, the voltage stress across each switch is reduced to half of the dc-link voltage, which makes the circuit applicable for HV battery system (such as 800 V) in EVs. In the proposed design, the integrated interleaved boost circuit modules allow low input current ripple to be achieved. Two step-up resonant circuit modules are then connected to the two interleaved legs with their outputs connected in series at the input of a current-fed high-frequency rectifier. Soft-switching commutation is achieved for all switches and diodes in the proposed converter. The descriptions of the proposed converter and its operating principles will be discussed in this article. A silicon-carbide-based hardware prototype with a rated power of 2.4 kW, 90–135 Vac/800 Vdc system has been tested in the laboratory. Results confirmed that a power factor of 0.97 and a peak efficiency of 97.9% were achieved. [ABSTRACT FROM AUTHOR]

A nonisolated integrated multiple output synchronous buck converter is proposed in this article to cater the auxiliary power supply requirements of e-mobility. The converter provides independently controlled multiple outputs with reduced switch count as compared to conventional separate buck converters as well as conventional synchronous buck converter. The operating principle and working of the proposed converter are discussed in detail for better understanding. As the dynamic behavior of the converter is similar to the conventional buck converter, a simple controller is designed and implemented in this work. The converter is simulated in MATLAB-Simulink. A laboratory prototype of single input–quadruple output (SIQO) converter is developed and operated under closed loop condition to validate and demonstrate its advantages. The prototype is developed by designing two inductors on a single core for increased compactness and reduced cost of the converter. Each output of the converter can be independently controlled by varying the duty ratio of the related switch, thereby eliminating the effective cross regulation problem. The efficiency of the proposed SIQO converter is 93.6%, with four output ports, which is higher than its category of converters reported earlier. A significant improvement in the calculated efficiency is observed with the replacement of conventional switches and diodes of the converter by SiC switches (96.1%). [ABSTRACT FROM AUTHOR]

Rapid widespread vehicle electrification has incentivized fast chargers to improve their performances. In this article, an integrated-magnetic-based differential-mode Ĉuk rectifier (IM-DMCR) as a universal battery supercharger is introduced. The design challenges associated with the high-power operation of IM-DMCR are outlined, and optimized solutions are presented. A SiC-based full-scale 60-kW experimental prototype for the IM-DMCR is built and tested to verify the design. [ABSTRACT FROM AUTHOR]

A coupled-inductor-based fourth-order buck converter is introduced in this article. The salient features of this topology are lower source current ripples like in conventional buck converter with input filter, no need of connecting an additional damping network across the input filter capacitor, additional flexibility provided by the coupling in the performance tuning, and the existing input C1–L1m structure itself acts as a ripple steering network. The detailed steady-state analysis is evolved and conditions for source current ripple reductions are formulated. Subsequently, small-signal analysis is established and a proportional plus integral plus derivative type controller is designed to ensure load voltage regulation. To enhance the dynamic performance, a two-loop voltage-mode controller is designed. The stability analysis of the closed-loop coupled-inductor-based buck converter is carried out through the eigenvalue sensitivity and participation factors approach. The impact of converter parameters on the converter system stability is discussed. In comparison with the single-loop voltage-mode controller, the two-loop voltage-mode controller is able to ensure that the closed-loop poles stay away from the jω-axis and, thus, the two-loop voltage-mode controller exhibits better dynamic performance. Analytical findings are validated on a 75 W, 60 to 36 V prototype converter. Steady-state and dynamic performance characterizing measurement results are given for validation of the concept. [ABSTRACT FROM AUTHOR]

To balance dc voltage, a two-module structure based on a dc–dc three-level boost converter is utilized. In this article, the possible operating modes for a two-module converter in the steady state are introduced. These modes are performed according to different states of opening or closing of the switches. Total 16 possible operating modes and the operation of different switches in the circuit are shown. The circuits for each operating mode are drawn according to the switch command signals. The relationships governing the system are given in different modes. These equations include the currents through three output capacitors and the inductor voltages of each module. The system is simulated by MATLAB/Simulink. The waveforms of the system are presented in two cases for different operating points. The operating mode of this structure is validated using simulations and experimental results. [ABSTRACT FROM AUTHOR]

A switching capacitor-based boost converter topological evolution is proposed in this article. Switching capacitor with dual-switch configuration is the basis for the topological evolution with common ground feature. The topologies evolved are capable of yielding high-voltage transformation ratio at smaller duty ratios like in Z-source dc–dc converter topologies. The front-end structure provides a voltage gain of 1/(1 − 2D) while the upstream circuit structure is compatible for embedding the voltage multiplier cells and thus gain enhancement becomes an easier task. On this basis, four different enhanced gain boost topologies with common ground feature [dual-switch-based switching-capacitor converter (DSSCC) Type-1 and -2, and dual-switch-based switching-capacitor fourth-order converter (DSSCFO) Type-1 and -2] are introduced in this article. In all these topologies, a small adjustment in the duty cycle is sufficient enough to ensure load voltage regulation even if the input supply voltage varies over wide ranges. Among these four proposed topologies, DSSCC Type-1 and DSSCFO Type-2 exhibit low source current ripple content due to the presence of inductance at the source side. Of these two, DSSCFO Type-2 exhibits low source current ripples as well as high voltage gain at moderate duty ratios. In view of this, detailed analysis and experimental investigations are established for DSSCFO Type-2. A comprehensive comparison of the proposed topologies with other reported topologies is given, wherein they exhibit identical as well as closely following voltage gain. A 220 V, 120 W, 50 kHz prototype is constructed for performance verification. Measurement results are provided to demonstrate the enhanced gain boosting along with low source current ripple features. [ABSTRACT FROM AUTHOR]

This article proposes the high-frequency link three-phase integrated-optimized power electronic transformer (PET) for electric vehicle (EV) charging infrastructure in the distribution network. The structural elements and configuration of PET significantly affect its design and performance. However, the different topologies of PET available in the literature did not consider the influence of the circuit’s structural elements with their parasitic components. Consequently, it violates the value of control variables which fails to accomplish essential control characteristics required for EV charging infrastructure in the smart distribution network. Therefore, in this article, detailed modeling and analysis of the proposed PET are carried out at each stage by incorporating its structural effect to analyze the circuit behavior during different operating conditions. As a result, it provides the design and operating constraints for the proposed PET, employed in the design procedure and control algorithm. Furthermore, the dual-degree control (DDC) method is proposed to utilize the structural framework and dual control variables of the proposed PET to meet out significant aspects of EV charging infrastructure in the distribution network such as wide range of voltage regulation, active control over the power flow, and soft-switching operation. Finally, a 4-kW prototype of the proposed PET is built up, which has a bidirectional power flow feature and isolated dc dual-port output terminals. Hardware testing and experimental results verify the effectiveness of the proposed PET based on the DDC method. [ABSTRACT FROM AUTHOR]

The control of very high switching frequency power electronic converter systems featuring latest generation wide bandgap devices requires current measurements with a very high bandwidth (BW) to achieve high closed-loop control dynamics. One example is an ultrahigh BW $\mathbf {4.8}$ MHz parallel-interleaved multilevel GaN inverter ac power source with a target large-signal output BW of $\mathbf {100}$ kHz. This work investigates the combination of commercially available low-frequency (LF) Hall-effect current sensors (BW $\mathbf {\approx 1}$ MHz) with suitable high-frequency (HF) sensors to extend the BW above $\mathbf {10}$ MHz, i.e., enough to measure the HF inductor current. Based on a conventional PCB-integrated Rogowski coil, for the HF sensor, three improved pickup coil (PUC) geometries based on proposals in the literature are investigated. The LF and HF sensor signals are combined with a precision fully differential combiner circuit. Design guidelines for the HF sensors as well as the combiner circuit are presented and thereby the influence of mismatches and tolerances is examined. The performance of the proposed HF sensors is experimentally verified and compared with previous solutions based on galvanically isolated inductor voltage sensing and a current transformer. The PUCs reach a BW $\mathbf {>50}$ MHz, which is an improvement by more than a factor of $\mathbf {50}$ compared to the fastest available Hall sensor. Furthermore, it is proven that all investigated sensors are capable to accurately measure the triangular inductor current ripple in a hardware prototype of the aforementioned ac power source. In a final step, the influence of common-mode (CM) disturbances originating from fast $\mathbf {{d}v/{d}t}$ switching transients on the sensor performance is analyzed. The presented current sensors achieve a CM rejection ratio of almost $\mathbf {100}$ dB. [ABSTRACT FROM AUTHOR]

Single-input dual-output (SIDO) converters have a common input and two different outputs. An inversely coupled inductor (CI) makes the converter compact by reducing the core size. This article presents the coupled inductor SIDO (CI-SIDO) buck, boost, and buck–boost converters. It is found that numerous patterns of inductor currents are possible for these CI-SIDO converters depending on the coupled inductor parameters and duty ratios. The inductor current patterns also depend on the gate pulse patterns. With the change in the patterns, inductor current ripples change. It is difficult to analyze the numerous possibilities of inductor current patterns for all the CI-SIDO converters. This article presents an approach to unify inductor current patterns and inductor current ripples in CI-SIDO converters by forming sectors of duty ratios. In each sector, the inductor current patterns and the inductor current ripples are different from other sectors. The formation of sectors of duty ratios is valid for all three CI-SIDO converters. The article also proposes a unified coupled inductor design with reduced inductor current ripples and reduced flux in the core. Experiments verify the analysis using laboratory prototypes. [ABSTRACT FROM AUTHOR]

This article discussesthe control method for an ac/dc rectifier system consisting of a three-phase diode rectifier, a buck converter, and an instantaneous reactive power compensator (IRPC). The IRPC makes the grid current sinusoidal by controlling only the instantaneous reactive power. Thus, it is possible to reduce the size of the dc capacitors and ac inductors. This article analyzes the overlap in the rectifier, derives the suitable gain in the damping control, and proposes a modified control method for the IRPC to reduce the current ripple. A 4.5-kW laboratory setup was assembled and examined to verify the theory developed in this article. As a result, the modified control method effectively suppresses the spike current around the overlap duration and damps the overshoot/ringing caused by the resonance. The proposed ac/dc rectifier exhibits an improved power conversion efficiency of 98.2%. [ABSTRACT FROM AUTHOR]

This article focuses on the coupled inductor single input dual output (CI-SIDO) boost converter topology. The CI-SIDO boost converter can be used in many practical applications, such as electric vehicles, renewable energy systems, and portable electronic devices. Several applications, such as battery charging, fuel cells, photovoltaic systems, and ultracapacitors, require ripple-free currents, as the lifetime of sources in these applications gets reduced by higher current ripples. However, there is no method in the existing literature to obtain a zero-ripple input current in the CI-SIDO boost converter. This article proposes an approach to design a CI-SIDO boost converter such that the ripple in input current is either zero or less than the maximum specified ripple limit. The analytical proofs of the design method are presented, and the usability analysis is evaluated by taking practical design examples. The effect of variations in the input voltage, CI parameters, and closed-loop control on the proposed design method is analyzed. The proposed design method is verified in experiments by laboratory prototype and in LTspice simulations. [ABSTRACT FROM AUTHOR]

Impedance-source inverters (ZSIs) are getting more attention in renewable energy generation over conventional inverters due to their inherent boosting ability and shoot-through immunity. However, most of the ZSI expansion abilities are somehow limited by the component stresses and poor performance, particularly at a low modulation index. In this article, a new coupled inductor-based switched quasi-ZSI is proposed to accomplish enhanced boost inversion at a high modulation index. It offers a robust boosting feature even with a very low turns ratio, which significantly reduces the passive circuit element's size. The working principle, steady-state analysis, and the design guidelines for selecting circuit parameters are addressed. The proposed inverter significantly improves the input current ripple with enhanced boosting with appropriate control of the impedance-network active switch. A comprehensive comparative analysis with allied topologies is presented to show the proposed inverter's effectiveness. The superior features offered are more suitable for renewable energy generation from low- and variable-voltage renewable sources, such as solar PV and fuel cells. A laboratory prototype is made for experimental verification. Analytical, MATLAB simulation and experimental results are presented to validate the proposed theory. [ABSTRACT FROM AUTHOR]

Nonisolated dc–dc converterswith multi-inputfeatures are very popular in the area of hybrid energy integration since they are compact and cost efficient compared to the isolated topologies. A dual-input hybrid step-up dc–dc converter (DIHDC) with a compact structure is introduced in this article. DIHDC operates based on the switched inductor technique. DIHDC has two inductors with equal values that are parallelly energized in the initial working modes (i.e., switch on condition) and dissipates the stored energy in series in the final working mode (switch off condition). Also, the proposed converter can be extended up to multiple inputs with slight modifications in the structure. Simple and compact structure, relatively higher efficiency, and good voltage conversion ratio are the potential merits of the new converter. Analysis of DIHDC in steady-state condition is explained elaborately and the simulation results are presented. Detailed dynamic analysis of the converter has been performed based on the small signal model of the converter and the necessary transfer functions are derived. A laboratory scale converter model is developed to confirm the efficient operation of DIHDC in realistic environments. [ABSTRACT FROM AUTHOR]

In this article, the open-circuit fault-tolerant operation of a multimode stacked switch rectifier leg is presented and investigated. A fault-tolerant control technique is proposed through the built-in circuit redundancy operation of the presented multimode stacked switch rectifier leg. A bidirectional CLLC resonant dc–dc converter that employs the presented leg is used to demonstrate the features of the presented control scheme. The proposed control can allow post fault operation of the converter to continue to deliver the demanded load power with soft-switching operation in case any switch experiences an open-circuit fault. In addition, the built-in circuit redundancy of the leg allows the resonant converter to operate in different operating modes, resulting in an enhanced control in regulating the output voltage while avoiding the switching frequency to diverge far from the resonant frequency, leading to better performance and improved efficiency with the complete soft-switching operation before and after the fault. To highlight the merits of the proposed fault-tolerant control in the multimode stacked switch rectifier leg, experimental results are provided on a 300-W resonant converter prototype with an input of 250 V and an output voltage of 400 V. [ABSTRACT FROM AUTHOR]

This article proposes a novel single-phase bridgeless Cuk-derived power factor corrected (PFC) converter with reduced component count for on-board EV charging application. The unique feature of this proposal is to design and operate the output inductor of the converter in discontinuous current mode for the complete power range to attain PFC naturally at ac mains, thereby not requiring the input voltage and input current sensing, which reduces the converter cost, and improves the power density as well as converter robustness to high-frequency noise. The converter control is very simple in operation and easy in implementation with only a single sensor-based voltage control loop. The semiconductor components voltage stress of the proposed power converter is lower when compared to the traditional Cuk converter. The simulation results from PSIM 11 and experimental results are given by testing a proof-of-concept hardware laboratory prototype to demonstrate the high performance of PFC operation of the proposed converter. [ABSTRACT FROM AUTHOR]

A novel electrostatic precipitator was developed for collecting and decomposing soot in exhaust gas from combustion devices, including diesel engines. In the precipitator, the dielectric surface works as a collection electrode.As one of the key processes in this technique is charging the dielectric surface, the surface potential distributions were first investigated using glass plates as the dielectric surfaces with a positively biased ac voltage applied to discharge electrodes placed on the glass plate. Results showed that positive ions created by the breakdown of air charged the surface, and the associated intermittent voltage was sufficient for building the surface potential. The area of PM adhesion was then investigated experimentally using real exhaust gas and numerically by simulating the trajectories of the charged particles. The results showed that the uneven surface potential was the essential factor involved in the collection of particles and that the unevenness was due to the intermittent voltage applied to the glass surface. Creating and utilizing the potential unevenness along the dielectric surface for particle collection made this system unique among ESPs (electrostatic precipitator) that have been researched. [ABSTRACT FROM AUTHOR]

An isolated matrix rectifier is promising as it can provide galvanic isolation and maintain high power density due to the high-frequency link when compared with dc link in voltage source converter based solutions. To increase power rating or extend the output dc voltage range, this article proposes the input-parallel–output-parallel (IPOP) and input-parallel–output-series (IPOS) modular structures. These modular structures can achieve favorable features such as modularity and scalability without circulating current issues. To facilitate the operation of an IPOS- or IPOP-connected isolated matrix rectifier, this article proposes a carrier-based modulation strategy. Compared to space vector modulation methods, the proposed carrier-based modulation strategy is preferable due to the low complexity even under a high number of modules. The proposed modulation method can well compensate for the duty cycle loss to reduce current harmonics. Compared to conventional modulation methods, the narrow pulse is reduced to achieve high current quality even at a low modulation index. Moreover, the common-mode voltage is reduced by 50%. Simulation and experimental results are provided to validate the feasibility and performance of the proposed carrier-based modulation method. [ABSTRACT FROM AUTHOR]

Local-measurement-based algorithms are relevant as primary protection for high voltage direct current (HVdc) grids due to the restriction in operation speed. The communication time delay significantly affects communication-based algorithms, therefore, they are mostly implemented as backup protection or for high-resistance fault detection. This article proposes a local derivative-based protection scheme for HVdc grids. Primary protection is based on the voltage derivative. Conversely, the backup and busbar protections are based on the current derivative. The proposed system is evaluated against low- and high-resistance fault case scenarios via simulation in PSCAD software. The voltage derivative-based algorithm provides a fast and accurate primary protection. On the other hand, the current derivative-based algorithm is implemented to operate when a failure is produced in the primary protection. The parallel operation of these two algorithms saves time when it comes to backup operation after primary protection's failure. Likewise, the busbar protection operates rapidly and selectively. Influence of the limiting inductor's size, sampling frequency, fault resistance, and noise disturbance on the performance of the proposed protection scheme are also analyzed. The presented protection scheme is capable of rapidly and selectively detecting faults up to 200 Ω while covering primary, backup and busbar protections. Moreover, only common local derivative-based algorithms are employed in addition to typical limiting inductor's sizes and relatively low sampling frequencies. [ABSTRACT FROM AUTHOR]

Dual-active-bridge (DAB) converters have been widely recognized as one promising topology for high-frequency-link power conversion applications. However, one critical issue concerning DAB converters is the transient dc-bias current due to the voltage-second imbalance, which may occur frequently in typical dynamic operations of DAB converters such as the start-up, sudden load or output voltage change, and power flow direction change. Due to the high-frequency operation, the dc-bias current of DAB converters will impose more harm to magnetic components because of the limited range of operating flux density and possible magnetic saturation compared with the counterpart low-frequency dc-bias current. Over the past several years, extensive researches have been conducted to address the high-frequency transient dc-bias current of DAB converters under different phase-shift modulation strategies such as single phase shift, extended phase shift, and triple phase shift. In this article, a comparative review of typical dc-bias current mitigation strategies under typical phase-shift strategies for DAB converters is presented. An experimental evaluation of selected strategies under various scenarios is conducted in terms of the settling time, inductor current stress, efficiency, switching number, and implementation complexity. This article ends up with an overview of high-frequency dc-bias mitigation strategies and a discussion for the further optimization. [ABSTRACT FROM AUTHOR]

This article deals with the impact of harmonic filters’ interactions in the aircraft grid, in particular, their influence on the control performance of each subsystem. The study has been carried out on a notional electrical system composed of two three-phase power converters—a voltage source inverter and an active front end. The beginning of the article presents the origin of the issue—trend of reducing the filter size and weight, which is especially true in the aircraft industry. Then, the roles of the filter and their design challenges are discussed. The next part of the article describes the controller’s constraints, its design, and the control system modeling approach, including a specially developed simulation tool used for the interactions analysis. Simulation results with the experimental verification are presented showing the interactions impact on the system dynamics. Finally, optimization of the filters under dynamic control constraints considering system’s components interaction are presented as the simulation tool application. [ABSTRACT FROM AUTHOR]

This article provides a simple methodology to achieve an optimized parameter design of the dual-loop control for grid-forming voltage source converters (VSCs) with LC filters. The optimized parameter design is conducted for the current inner loop and voltage outer loop independently without any coupling, and the design processes of these two loops are exactly the same. Moreover, in the proposed design, standard analysis and design tools, e.g., pole map and Bode-plot can be directly employed while complex formula solving is needless. Therefore, this methodology is easy to implement for a practical engineering. In addition, contrary to common sense, it has been identified that the proportional controller in the outer loop has a negligible impact on the control bandwidth of typical medium power rating VSCs and thus can be eliminated to further simplify the design process and control structure. The left resonant controller can then be refined to achieve a significantly improved dynamic performance of the output voltage of VSCs. Detailed processes and considerations of the proposed design methodology are introduced and analyzed. Its effectiveness and performance are carefully verified by experimental results from a single-phase scaled-down VSC prototype. [ABSTRACT FROM AUTHOR]

The limited voltage gain characteristic of the mainstream dc–dc converter restricts the application in single-stage light electric vehicles’ (LEVs) chargers. Typically, the battery voltage of an LEV is in the range from 24 to 72 V. Thus, while implementing the single-stage LEVs’ chargers, a line- or high-frequency transformer is essentially required. The utilization of transformer, however, compromises the overall cost, size, and efficiency of LEV chargers. Therefore, a transformerless single-stage bridgeless charger topology is presented in this article, aiming to realize a simple, reliable, efficient, and low-cost charger for the LEVs. The presented topology utilizes a switched inductor single ended primary inductance converter (SISEPIC) to achieve a high step-down dc voltage gain. Furthermore, the active power factor correction is incorporated to ensure enhanced power quality (low total harmonics distortion and unity power factor) at the ac supply side during constant current and constant voltage state charging. Additionally, this charger is controlled by employing reduced sensing devices and control complexities. Both simulation and experimental validations are provided to manifest the effectiveness of this SISEPIC charger topology for LEVs. [ABSTRACT FROM AUTHOR]

There is a growing demand in the marketplace for wirelessly powered consumer applications. Some of these low-power applications require wireless power transfer with bidirectional power flow. For such consumer applications, this article proposes a new bidirectional wireless power transfer (BD-WPT) topology that facilitates wireless power transfers in both directions using fewer components. This article describes the operating principles of the topology in detail and presents a mathematical model to predict and investigate its performance. Besides, a control method with synchronization is also proposed for this topology to regulate power transfer in both directions. Simulations and theoretical results are presented in comparison to the measured results of a 60-W prototype BD-WPT to demonstrate the viability of the proposed converter topology. Results are convincing and indicate that the proposed converter is suitable for low-power applications being low cost, reliable, and efficient. [ABSTRACT FROM AUTHOR]

Current-fed dual active bridge dc–dc converters are suited for renewable energy systems such as solar photovoltaic and fuel cells, due to the advantages of small input current ripple and wide input voltage range. In this article, a current-fed dual active bridge dc–dc converter based on pulse width modulation plus phase shift control is studied. The working principle and zero-voltage switching (ZVS) conditions of the converter are analyzed in depth, and it is proved mathematically for the first time that all switches can naturally achieve ZVS independently of dc inductance and leakage inductance under a wide input voltage range within full load range. Based on maximum power transfer, peak current, and root mean square (RMS) current analysis, optimal dc inductance and leakage inductance design to obtain low inductor RMS current is proposed. In addition, the detailed loss breakdown was implemented by comparing it with the nonoptimized case. The effectiveness of the theoretical analysis and design method has been verified by experimental results. [ABSTRACT FROM AUTHOR]

The high-step-up dc–dc converter is a key for numerous renewable-energy-based applications such as photovoltaic and fuel cells. Due to the low-voltage output of these renewable sources, a high-step-up stage is required, which bridges the gap of renewable to utility state. In this article, a noncoupled high-step-up $Z$ -source dc–dc converter, utilizing a quasi- $Z$ -source (QZS) network, is presented. The proposed topology is a combination of QZS structure and switched-capacitor cells, which maintains continuous input current and low-voltage stress across capacitors. In addition to these merits, the converter can achieve a high-step-up voltage at a low duty cycle, which results in lower conduction losses on semiconductor devices. The working principle, steady-state waveforms, related expressions, and comparative study are included in this article. The proposed converter can be extended for the use of a single-stage step-up $Z$ -source inverter and also for hybrid output applications. Finally, experimental results are presented to verify the feasibility of the converter in both open and closed loops. [ABSTRACT FROM AUTHOR]

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

In this article, a robust adaptive controller based on active disturbance rejection control algorithm is proposed for interleaved dc–dc Boost converter for fuel cell application. The unknown load power and parametric variations are regarded as part of the total disturbance, which is estimated by extended-state-observer (ESO), and then canceled in the control law. Within the proposed controller, the parameter ${b_0}$ is adapted in real-time to reduce the estimation burden of ESO. It is shown that compared with the conventional controller, the proposed controller can achieve significant improvement in terms of robustness, the strong antidisturbance performance can be maintained with the varied number of active phases. Finally, simulation and experimental results validate the effectiveness and superiority of the proposed controller. [ABSTRACT FROM AUTHOR]

A reduced sensor based bridgeless boost (BLB) power factor correction (PFC) converter fed full-bridge inductor–inductor capacitor (FBLLC) converter for electric vehicle (EV) charging, is presented in this article. This converter is a twin stage converter, where the first stage is a PFC-BLB converter operating in continuous conduction mode of its boost inductors, and the second stage is an FBLLC converter, which converts the output voltage of the PFC-BLB converter to an isolated low voltage for constant current/constant voltage (CC/CV) charging of an EV battery. The BLB converter is switched at fixed frequency using pulsewidth modulated control, whereas FBLLC converter employs a pulse frequency modulation control to enable CC/CV charging of EV battery. An experimental prototype of EV charger is developed and the digital control of PFC-BLB and FBLLC converter, is implemented using a 32 bit $TMS320F28035$ digital signal processor to charge an EV battery with a maximum power of $2.7\text{ kW}$ and a current of $50\text{ A}$. [ABSTRACT FROM AUTHOR]