Search

Tap changers are commonly used to maintain the limits in medium-voltage lines. Initially based on electromechanical switches, efforts have been made since the 1990's to reduce maintenance expenses with thyristor-based versions. Among the methods to limit the short-circuiting current in commutating taps, the multiwinding coil has demonstrated, during decades of use in the low-voltage field, to be reliable and cheap. Two previous papers showed that multiwinding changers can be applied to medium-voltage lines up to 34.5 kV, 15 MVA with no parallel or series thyristor association. This paper proposes a new topology, based on a double array of tap switches per phase, allowing for step-up the power from 15 to 36 MVA and insertion in any point of the line with no connection to the head transformer. A comparative cost analysis gives technical and economical results for a typical 10 MVA, 34.5 kV stabilizer demonstrating the advantages of the proposed circuit over the electronic single array topology and the classic mechanical solutions. [ABSTRACT FROM PUBLISHER]

This paper offers a new approach for far-field high-resolution imaging of conducting obstacles based on arrays of frequency-multiplexed subwavelength resonant elements. Each resonator is a circular aperture in a metallic screen that is strongly miniaturized by means of loading by a thin epsilon-negative and near-zero metamaterial (MTM) liner. Each MTM-lined aperture exhibits a fano-shape transmission profile, i.e., a peak followed by a minimum, and the resonance frequencies of different apertures are chosen such that the resonance of one lies within/very close to the antiresonance of the other to ensure strong decoupling. This paper shows that blocking an aperture using a conducting disc removes the corresponding resonance peak/minimum from the transmission/far-field amplitude spectrum, enabling far-field detection of any distribution of such obstacles with a spatial resolution determined by the aperture sizes, which measure less than one-sixth of free-space wavelength at their respective resonance frequencies. The proposed imaging mechanism is verified through full-wave HFSS simulations as well as far-field measurements. Some challenges associated with this approach are then discussed. [ABSTRACT FROM AUTHOR]

This paper proposes a dual-coupled LCC-compen-sated inductive power transfer system with a compact magnetic coupler to improve misalignment performance. In the magnetic coupler, the main coils form the first coupling, and compensation inductors are integrated with the main coils to form a second coupling. In the design presented in this paper, the main coils are unipolar and the compensation inductors are in a Double D structure. The fundamental harmonics approximation method is used to analyze the circuit, and the couplings between the main coils and compensation inductors are considered to determine the net power flow. In misalignment cases, it is shown that the coupling between the compensation inductors, and the cross couplings between the compensation inductors and main coils, contribute to increasing the system power. A 3.5 kW prototype is designed and implemented to validate the proposed dual-coupled system. The primary coil size is \text450 mm\times \text450 mm, and the secondary coil size is \text300 mm\times \text300 mm. Experimental results show that the proposed dual-coupled system can significantly improve the misalignment performance, and retains at least 56.8% and 82.6% of the well-aligned power at 150 mm misalignment in the x- and y-directions, respectively. [ABSTRACT FROM PUBLISHER]

This paper introduces a non-isolated high step-up dc–dc converter with dual coupled inductors suitable for distributed generation applications. By implementing an input parallel connection, the proposed dc–dc structure inherits shared input current with low ripple, which also requires small capacitive filter at its input. Moreover, this topology can reach high voltage gain by using dual coupled inductors in series connection at the output stage. The proposed converter uses active clamp circuits with a shared clamp capacitor for the main switches. In addition to the active clamp circuit, the leakage energy is recycled to the output by using an integrated regenerative snubber. Indeed, these circuits allow soft-switching conditions, i.e., zero voltage switching and zero current switching for active and passive switching devices, respectively. The mentioned features along with a common ground connection of the input and output make the proposed topology a proper candidate for transformer-less grid-connected photovoltaic systems. The operating performance, analysis and mathematical derivations of the proposed dc–dc converter have been demonstrated in the paper. Moreover, the main features of the proposed converter have been verified through experimental results of a 1-kW laboratory prototype. [ABSTRACT FROM PUBLISHER]

This paper presents a procedure for evaluating self-capacitances and parasitic capacitors between physically adjacent turns in multiconductor systems—with a special focus on single-layer air-core inductors. To this end, the paper proposes the use of standard cells, which correspond to a minimal and basic turn, layer, or macrolevel arrangement of a winding in reference to its patterns of stored electrostatic energy. A standard cell embraces mathematical rules derived by means of a curve fitting approach through a set of finite element analysis (FEA) simulations. Besides, it is applied in a matching routine wherein self- and stray capacitances are evaluated according to the relative position of each turn, layer, or macrolevel arrangement along the length of the winding. Finally, the analytical technique is validated by comparing frequency-domain results obtained from an implemented SPICE model and laboratory measurements. [ABSTRACT FROM PUBLISHER]

To support the development of high-frequency ac microgrids in terms of compact design, high-voltage gain and low total harmonic distortion (THD), a buck–boost dual-leg-integrated step-up inverter is proposed in this paper. The inverter is formed by integrating a buck–boost converter into a conventional single-phase full-bridge inverter by sharing the upper switch and the body diode of the lower switch in both bridge-legs. Consequently, the component count is significantly reduced over the step-up inverter counterparts. In addition, to address the drawbacks of hybrid modulation methods adopted by existing dual-leg-integrated inverters, such as double-variable control, and high THD of output voltage/current at high input voltage and heavy load conditions, unipolar frequency doubling sinusoidal pulse width modulation scheme is adopted in this inverter. As a result, the modulation ratio M becomes the only control variable to regulate the output voltage/current and the control is simplified. The THD of the proposed inverter output can remain low throughout the entire input voltage range and load power range. This paper presents the topology derivation procedure, operation principle, and steady-state characteristics of the proposed inverter. To validate the effectiveness of theory, experimental results of a 400 W hardware prototype, where the output voltage frequency is at 500 Hz, are reported. [ABSTRACT FROM PUBLISHER]

In this paper, a new structure of nonisolated boost dc–dc converters based on voltage-lift technique is proposed. In comparison with conventional nonisolated boost dc–dc converters, the proposed converter generates higher voltage gain. In this paper, the relations between voltage and current of all elements in continuous conduction mode and discontinuous conduction mode are calculated as well as voltage gain in each mode. Then, the critical inductance and stress of switch current are extracted. Finally, the validity of given theories is examined by using the experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, two structures are proposed for the switched-inductor quasi-Z-source inverter. In the proposed structures to extend the voltage gain of inverter, two new switched-inductor structures are used. In the proposed structures, voltage across the capacitors in the Z-source network and in the switched-inductor is symmetric and small. The other advantage of proposed inverters is known as achieving higher voltage gain per smaller duty cycle ratio (of shoot-through). Compared with a conventional continuous input current switched-inductor quasi-Z-source inverter at the same gain voltage, there is less of a ripple of input current in the proposed inverters. In this paper, at first the both the conventional and the proposed switched-inductor Z-source inventers are thoroughly investigated to find out their governing relations. Then, the proposed Z-source inverters are compared with the conventional ones by simulating them to assess their performance efficiency. Next, applying the simple boost pulse width modulation the simulation is carried out with PSCAD/EMTDC software. After that, to evaluate the obtained results, the prototypes of the proposed inverters with 48 Vdc input voltage are used. [ABSTRACT FROM PUBLISHER]

A comprehensive analysis for a family of two-level pulsewidth modulation plus phase-shift (PPS)-modulated-isolated-bidirectional dc–dc converters is presented in this paper. Compared with the traditional phase-shift control, the PPS control features reduced current stresses, reduced conduction losses, guaranteed zero-voltage switching (ZVS) operation, and wide conversion-ratio variation range. In this paper, all eight operation modes are revealed, and then the unified solution of the power transmission capability for each mode is proposed, applicable for any two-level PPS converters. Based on the unified solution, component stresses and ZVS operation are analyzed to assist component selection. Most importantly, the control maps for three different combinations of the two-level PPS converters are proposed, to assist converter operation and design in the low-circulating-current region. In the control map, a circuit parameter k is proposed and its upper limit is found, providing a design limit to select switching frequency, leakage inductance, turns ratio, and power level. A 29–67 V/380 V prototype—the combination of group C plus group A—rated at 100–1000 W was built. The analysis is verified by both simulation and experimental results. [ABSTRACT FROM PUBLISHER]

Microinverters require high voltage gain capability for interfacing the low dc voltage output of photovoltaic (PV) module to single-phase ac grid. A two-stage nonisolated inverter is proposed in this paper, with a first boost stage and a second traditional pulse width modulated grid-tied inverter stage. The proposed boost stage consists of a coupled inductor added with a voltage multiplier to achieve the required high voltage gain at high efficiency and to operate over a wide input voltage range. Among the coupled inductor topologies, adding a clamp circuit is a common solution to limit the voltage spike caused by leakage inductance. In the proposed converter, the resonance between the coupled inductor and voltage multiplier is used to address the issue of voltage spike, thereby reducing both component count and device voltage stress. Detailed analysis and design procedure of the proposed converter is presented in this paper. Experimental results of a 250-W microinverter are presented to validate the proposed converter. [ABSTRACT FROM PUBLISHER]

A new modulated carrier control (MCC) method is proposed in this paper for a power factor correction (PFC) boost converter, which provides high power factor (PF) and low total harmonic distortion (THD) in wide input voltage and load range. The proposed MCC method employs a zero current duration (ZCD) demodulator that detects ZCD in each switching cycle to estimate current conduction duration of the boost inductor. Using the estimated signal of the ZCD demodulator, the proposed controller generates a compensated duty signal with a PFC converter to properly operate in continuous conduction mode (CCM) or discontinuous conduction mode (DCM). Unlike the conventional MCC PFC converter where the line current is distorted in DCM resulting in poor PF and high THD, the proposed MCC method can provide higher PFC performance regardless of CCM and DCM while maintaining the simple control loop of conventional MCC control method that does not require inner current loop and using relatively small inductance. In this paper, the operational principle of the proposed method has been discussed. To verify the proposed method, it has been tested on a 400-W PFC boost converter. [ABSTRACT FROM AUTHOR]

This paper proposes a single-phase power factor correction (PFC) rectifier to achieve high power factor, wide output voltage range, and ripple power decoupling without using electrolytic capacitors. It consists of two parts: PFC circuit and output voltage regulation circuit. The load side is involved in both parts, which is different from the regular two-stage conversion structure. The proposed rectifier can be directly applied to low voltage cases due to the wide output voltage range. And the decoupling capacitor voltage can be smaller than the peak grid voltage, which reduces the voltage stress. Besides, the low-frequency ripple power buffer is implemented without a dedicated power-buffering controller. This paper first introduces the circuit structure, operation principles, and control method. Then, the system design consideration is given. Finally, the effectiveness of the proposed topology is verified by the simulations and experimental results. [ABSTRACT FROM AUTHOR]

In this paper, two resistive matching networks are proposed, which can maintain the resistive transferring property under different load conditions. The high-frequency converter based on the resistive network can adequately achieve the soft-switching characteristics within a large load variation range, which helps to reduce switching losses and improve system efficiency. At the same time, a detailed design method for planar spiral inductor is described. In addition, the quality factor characteristics of different winding structures are analyzed. A 20-MHz high-frequency dc/dc converter based on the T-type matching network and circular spiral inductor is designed in this paper. The experimental results verify the advantages of the proposed resistive matching network and spiral inductor. [ABSTRACT FROM AUTHOR]

An optimal dual-phase-shift control strategy of an isolated buck–boost converter is proposed in this paper. The theoretical analysis of dual-phase-shift control strategy is complemented, and the three-dimensional graphs of the output current versus two control variables are given. The optimal operating point is determined by the peak current of a clamped inductor and is shown as control trajectories in the three-dimensional graphs. Moreover, with the optimal dual-phase-shift control strategy, low current value, soft-switching operation, wide input voltage range regulation, whole load range regulation, and high-efficiency performance can be achieved. Furthermore, parameter design method deriving from the minimum peak current of the clamped inductor is given. At the end of this paper, a 1000 W-output prototype is fabricated to verify the effectiveness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

This paper presents a shutdown dose rate (SDR) calculation to estimate a newly developed preliminary concept of the equatorial port model for the Korean fusion demonstration reactor (K-DEMO). The equatorial port model was designed to provide effective radiation shielding abilities adopting the port shielding block and labyrinth structure, which was integrated into the modified K-DEMO neutronic analysis model by the Monte Carlo automatic modeling system. A rigorous two-step method was applied to couple transport (MCNP) and activation (FISPACT) codes according to three steps of calculation procedures. The results of neutron flux and decay gamma transport calculation for the equatorial port area have been indicated in this paper. The SDR calculation result near the equatorial port area reveals that a dose level in the equatorial port interspace was below $100~\mu $ Sv/h after 12 days of the shutdown. Shielding blocks and two labyrinth structures prove that they effectively attenuate neutrons on the current concept of the equatorial port model. [ABSTRACT FROM AUTHOR]

This paper presents a single-stage nonisolated switched capacitor ac–dc converter for power-factor correction (PFC). This converter features reduced passive components, single switch, transformerless high voltage gain, and improves the power factor, reduces total harmonic distortion, and voltage stress across the switch. The peak current mode with a dynamic resonant perturbation scheme compensates the subharmonics that exist at zero crossing of the source current is implemented for PFC. In this paper, the principle of operation, large signal modeling of the circuit, and control method for the proposed PFC converter are provided. [ABSTRACT FROM PUBLISHER]

With offline single-phase power supplies moving toward the megahertz switching frequency range, the converter's bus capacitor becomes the bottleneck of further improvement of power density. Partial constant power operation is effective in reducing the bus capacitance and capacitor current stress for low-power applications. However, its impact on circuit design and operation design has not been studied thoroughly. With the developed circuit operation and loss model, this paper presents design considerations and power loss analysis of megahertz ac/dc converters in partial constant power operation. An adaptive constant power control is also proposed, based on the developed models, to improve the light-load efficiency and power factor. A 65 W, megahertz critical conduction mode GaN-based ac/dc converter prototype has been developed to validate the analysis and circuit operation method. Compared with power factor correction (PFC) operation, partial constant power control exhibits an efficiency drop of less than 1%. However, a 50% reduction of bus capacitance can be realized. With the proposed adaptive constant power control, the light-load efficiency and power factor can be improved to be a level similar to the PFC operation. This paper ends with a discussion of the possibility of extending the proposed operation method to higher power applications. [ABSTRACT FROM PUBLISHER]

This paper presents a systematic and comprehensive approach for differential mode (DM) electromagnetic interference (EMI) filter design in a three-phase boost-type power factor correction (PFC) rectifier. Since the DM EMI filter forms a significant portion of the overall filter as well as converter volume, the reduction of DM filter component size is kept as a major objective in the filter design process in order to improve the power density. In addition to the objectives of volume optimization and conducted emission attenuation requirement to comply with the EMI standard, the filter design process also ensures a near-unity power factor operation with the optimal set of EMI filter parameters. To accomplish this, the paper analyzes the effect of EMI filter component selection on the overall lower order (1–100 kHz) frequency response, which is important for evaluating the dynamic response and stability. The results from the proposed design approach are validated through simulation, the DM Bode plot, and frequency response of the input current with and without EMI filter. As a proof-of-concept verification, the proposed EMI filter is implemented in a 4-kW three-phase boost-PFC prototype, which demonstrates minimal phase displacement (<5°) of the input current. [ABSTRACT FROM PUBLISHER]

A new isolated single-stage soft-switching power-factor-correction (S4 PFC) driver for supplying light-emitting diodes (LEDs) is introduced in this paper. In the proposed LED driver, the switches voltage stress and also the dc-bus voltage is limited to the peak of the line voltage. Hence, low voltage rated mosfets and diodes can be used. The efficiency is improved because the switches are turned on under zero current switching (ZCS) condition and turned off under zero voltage zero current switching (ZVZCS) condition. Also, no current feedback is required since the converter provides an output current independent of output voltage. In this paper, operating principle of the proposed LED driver is presented and design considerations are discussed. To verify the theoretical analysis, a laboratory prototype of the proposed converter for supplying a 50 W/70 V LED module from 220 Vrms/50 Hz ac mains is implemented, and the experimental results are presented. Since current feedback is not used, dimming property and operation for universal voltage range is not achievable. [ABSTRACT FROM PUBLISHER]

In applications that demand single-input dual-output (SIDO) or dual-input single-output (DISO) dc–dc converters, employing two separate single-input single-output (SISO) converters is a solution. However, the number of components is doubled, resulting in high overall cost. In order to reduce costs, this paper proposes a novel topology synthesis methodology, with which a variety of SIDO and DISO dc–dc converters with reduced components can be derived. The principle of topology synthesis states that integrated SIDO and DISO dc–dc converters can be easily developed from conventional SISO converters by replacing a diode with a basic cell inclusive of additional input/output port. The principle is effective for many SISO dc–dc converters, and as an example, topology synthesis based on buck, boost, buck–boost, Cuk, sepic, and zeta SISO converters is performed in this paper. In order to achieve better understanding of the proposed converters, the integrated SIDO Cuk converter is specifically analyzed and experimentally verified. In comparison with the conventional scheme of two separate SISO Cuk converters, good cross regulation is retained while the number of diodes, inductors, and capacitors is reduced in the proposed SIDO Cuk converter. In addition, zero-voltage-switching operation of one switch is achieved, contributing to lower switching losses. Finally, a prototype circuit with 48-V input and 156 V/1 A, 24 V/4 A outputs is built to validate the theoretical analysis. [ABSTRACT FROM PUBLISHER]

A switched-capacitor-based dual-switch dc–dc converter with a high-boost voltage gain is proposed in this paper. The proposed converter can obtain a high-voltage gain with a small duty cycle, which decreases the voltage stress and the conduction loss on the power switches. This paper presents the key waveforms, the operating principles at the continuous conduction mode and the discontinuous conduction mode, and the parameter design. Moreover, a comparison between the proposed converter and other nonisolated converters has been completed. To verify the operating principle, a 200 W prototype is constructed with an input voltage of 25–50 V and an output voltage of 200 V. The simulation and experimental results are shown. [ABSTRACT FROM PUBLISHER]

This paper proposes a decentralized current-sharing control strategy to endow fast transient response to paralleled dc–dc converters systems, such as dc microgrids or distributed power systems. The proposed controller consist of two main control loops: an external voltage droop control for current-sharing proposes and an internal current loop. The external droop control loop is designed as a voltage loop with embedded virtual impedance, which avoids the use of a slow voltage loop and a separate extra virtual impedance loop that may limit the system bandwidth. The internal current loop, thanks to the external control loop simplification, plays a major role in the system bandwidth, so that an adaptive proportional-integral (PI) controller is proposed for this matter. In the paper, two different droop control methods have been modeling, designed, simulated, and tested: The conventional virtual-impedance-loop based V–I droop and the proposed embedded-virtual-impedance based I–V droop. In order to compare the dynamic response performances between two droop controllers, their state-space models have been developed and analyzed in this paper. The results show that the dynamic response of the I–V droop control is faster than that of the conventional V–I droop control. Furthermore, by analyzing the effects from I–V droop control parameters, the errors can be reduced faster by enlarging the proportional terms, but with no fluctuations, and then completely eliminated by restoring back to small proportional values. Meanwhile, there exists a tradeoff phenomenon between the fast dynamic response and good steady-state performance; thus, an adaptive PI controller is proposed to both improve dynamic response and guarantee good steady-state performance simultaneously. Experimental results are shown to verify the accuracy of the models and the effectiveness of the proposed control framework. [ABSTRACT FROM PUBLISHER]

The halogen volatile organic compound (VOC) is a common industrial pollutant, mainly including trichloroethylene, dichloromethane, trichloroacetic acid, chloro-fluoro-carbons, carbon tetrachloride, trihalomethans, chlorodifuoromethanes, hydrofluorocarbons, and some other fluor alkaline, ether, and amine. The halogen VOCs have reproductive toxicity, immunotoxicity, and neurotoxicity. The traditional methods for treating them include masking method, dilution method, chemical oxidation method, incineration method, UV oxidation method, photocatalytic oxidation method, absorption method, and biological method. In this paper, advantages and disadvantages of traditional methods have been studied and analyzed. A new plasma technology has been put forward, which has the advantage of the rapid reaction to ambient temperature, wide applications, system compactness, simplicity of operation and short residual time, and the plasma technology is especially appropriate for the decomposition of VOCs. At present, as for the control of VOCs, the plasma technology has drawn much attention as an energy-saving technology. In this paper, the equipment for the decomposition of halogen VOCs has been analyzed, including the plasma rectors, power characteristics, operation conditions, and the decomposition mechanisms of C2HCl3, CH2Cl2, C2H3Cl3, CCl4, CHCl3, CF4, C2F6, and SF6 have been investigated and concluded. Finally, it is concluded that the combination of the plasma technology with traditional methods would be main direction of study in the future. [ABSTRACT FROM AUTHOR]

In this paper, new half-bridge and full-bridge topologies for a switched-boost inverter are proposed. These topologies have a high boost factor in comparison with conventional types. In addition, the proposed topologies have continuous input current and can generate zero-voltage level in output. In this paper, the operation of the proposed inverters in different operating modes is analyzed. Then, the values of inductors and capacitors are designed. Moreover, the used switching pattern and its logical diagram are introduced. A comprehensive comparison between the proposed and conventional topologies in terms of the boost factor, the number of elements, and the efficiency shows the good features of the proposed inverters. Finally, to verify correct operation of the proposed topologies and derived equations, simulation and experimental results are presented. [ABSTRACT FROM AUTHOR]

This paper presents a phase-shifted dual-half-bridge converter, which achieves zero-voltage switching (ZVS) for the leading-leg switches and zero-current switching (ZCS) for the lagging-leg switches. The proposed converter contains two paralleled half-bridge inverters in the primary side. The rectifier stage is composed of six diodes connected with the form of full-bridge rectification. The ZVS condition is created by the output filter inductor and leakage inductor, while the ZCS condition is created by the blocking capacitors. A wide range of soft-switching operation can be achieved with small leakage inductors. Compared with the traditional phase-shifted full-bridge converter, the proposed converter can obtain a three-level output rectified voltage, and the power is transferred from the primary side to the secondary side during the whole period, which can significantly reduce the current ripple of the output filter inductor. In this paper, the operation principle and relevant analysis are presented. A laboratory prototype is built to verify the performance of the proposed converter. [ABSTRACT FROM PUBLISHER]

This paper proposes a new bidirectional resonant dc–dc converter suitable for wide voltage gain range applications (e.g., energy storage systems). The proposed converter overcomes the narrow voltage gain range of conventional resonant dc–dc converters, and meanwhile achieves high efficiency throughout the wide range of operation voltage. It is achieved by configuring a full-bridge mode and a half-bridge mode operation during each switching cycle. A fixed-frequency phase-shift control scheme is proposed and the normalized voltage gain can be always from 0.5 to 1, regardless of the load. The transformer root-mean-square (rms) currents in both the forward and reverse power flow directions have a small variation with respect to the voltage gain, which is beneficial to the conduction losses reduction throughout a wide voltage range. Moreover, the power devices are soft-switched for minimum switching losses. The operation principles and characteristics of the proposed converter are firstly analyzed in this paper. Then the analytical solutions for the voltage gain, soft-switching, and rms currents are derived, which facilitates the parameters design and optimization. Finally, the proposed topology and analysis are verified with experimental results obtained from a 1-kW converter prototype. [ABSTRACT FROM PUBLISHER]

This paper proposes a comprehensive analytical LCL filter design method for three-phase two-level power factor correction rectifiers (PFCs). The high-frequency converter current ripple generates the high-frequency current harmonics that need to be attenuated with respect to the grid standards. Studying the high-frequency current of each element proposes a noniterative solution for designing an LCL filter. In this paper, the converter current ripple is thoroughly analyzed to generalize the current ripple behavior and find the maximum current ripple for sinusoidal pulse width modulation (PWM) and third-harmonic injection PWM. Consequently, the current ripple is used to accurately determine the required filter capacitance based on the maximum charge of the filter capacitor. To choose the grid-side inductance, two methods are investigated. First method uses the structure of the damping to express the grid-side filter inductance as a function of the converter current ripple. Reducing the power loss in the filter and optimizing the grid-side filter inductance is the main focus of the second method which is achieved by employing line impedance stabilization network (LISN). Accordingly, two LCL filters are designed for a 5 kW silicon-carbide-based three-phase PFC. Various experimental scenarios are performed to verify the filters attenuation and performance. [ABSTRACT FROM PUBLISHER]

This paper presents a hybrid nonisolated dc–dc commutation cell, which is generated by the integration between conventional commutation cell and ladder-type passive switched capacitor (SC) cell. From the resulted hybrid cell are derived three different dc–dc converters: a buck-type, a boost-type, and a buck–boost-type. The three structures are analyzed in this paper and are presented the topological stages, static gain characteristics in continuous conduction mode and discontinuous conduction mode, steady-state analysis. The analyses are generalized in relation to the number of switched-capacitor cells employed, which allows the increase of the rated gain of the converters by adding more SC cells. In addition, the proposed hybrid nonisolated dc–dc commutation divides naturally the voltage stress among the semiconductors and capacitors of the power stage. A 1-kW prototype was developed to verify the operation of the three proposed converters and their theoretical analysis. For the buck-type topology, designed with an input voltage of 600 V and output voltage of 450 V, a peak efficiency of 99.2% and efficiency at rated power of 99% were obtained. [ABSTRACT FROM PUBLISHER]

Replacing the batteries of wearable medical devices is an inconvenience to the user. Wireless power transfer (WPT) could be a solution for this problem. However, the structure should be compact to satisfy the wearable device requirements and the power efficiency should be as high as possible for prolonging the user experience. Besides, as algorithms embedded in these devices become more complex, the device power consumption also increases. Fulfilling these specifications in a compact structure with better efficiency is the aim of this research paper. This paper proposes a power processing module for WPT applications. This module is embedded within the WPT path to convert receiving end ac power to dc power, and to simultaneously provide multiple dc–dc power conversion for wearable medical devices. The ac–dc circuit is specifically designed using a compact topology to convert wireless ac power to stable dc power. The dc power is further regulated by different mode controls either to perform battery charging or to provide independent voltage supplies to dc loads. The integrated circuit occupies an area of 1.9 × 2.3 mm when implemented on a 0.25 μm high voltage CMOS process. [ABSTRACT FROM AUTHOR]

A novel hybrid pulse width modulation (PWM) technique is proposed in this paper for two parallel interleaved, two-level, three-phase voltage source inverters (VSIs). The two parallel interleaved VSIs are analyzed as a three-level (3L) inverter. A 3L inverter provides minimum line current ripple when nearest three voltage vectors are applied. In this paper, a novel carrier-based PWM technique is developed that ensures the application of nearest voltage vectors, keeping average circulating current to zero over a switching period. For carrier-based implementation of the proposed PWM, generalized common-mode (CM) offsets are derived in terms of maximum and minimum values of reference signals. Each 3L space-vector sector is divided into seven subsectors. For each subsector, a CM offset is calculated, addition of which to reference signals ensures the minimum line current ripple and zero average circulating current. Simulation and experimental results are provided to validate the proposed technique. [ABSTRACT FROM PUBLISHER]

The phase-shifted full-bridge (PSFB) converter is widely employed in high-power applications. However, circulating current, narrow range of zero-voltage switching (ZVS), duty-cycle loss, and secondary parasitic oscillation are the main drawbacks of the traditional PSFB converter. This paper proposes an improved full-bridge converter to solve the drawbacks of the traditional PSFB converter. In the proposed converter, a coupled inductor with three windings is introduced to adjust the available ZVS energy and to transfer power to the output side during freewheeling period. Due to this structure, output filter requirement, circulating current, the required ZVS energy, and secondary voltage oscillation can be reduced. Thus, the proposed converter can obtain higher conversion efficiency than the traditional PSFB converter. In this paper, the detailed operation principles and experimental results are presented. [ABSTRACT FROM PUBLISHER]

The development of a high static gain dc–dc converter with the integration of the voltage multiplier cell and the coupled inductors operating with soft switching is presented in this paper. The use of coupled inductors and voltage multiplier techniques allow the operation with low switch voltage and low conduction losses. The switch turn-on commutation occurs with zero current switching due to the presence of the coupled-inductor leakage inductance. The leakage inductance also reduces the reverse recovery current of all diodes. The zero voltage switching at the power switch turn-off is obtained with the inclusion of only a diode and a snubber capacitor per phase, without the use of auxiliary switches. The soft-switching range is independent of the load and is maintained even with a light load. The theoretical analysis, design procedure, and experimental results are presented in this paper. A two-phase boost converter with one voltage multiplier and coupling inductors was built with an input voltage $V_{{\text{in}}}= { \text{24 V}}, output voltage Vo= { \text{432 V}}, and output power Po= { \text{400 W}}. The efficiency obtained is equal to 94.55% at the nominal power. [ABSTRACT FROM PUBLISHER]

Sheppard–Taylor power factor correction (ST-PFC) rectifier could obtain a high power factor due to its capability of overcoming the control detuning issue. However, it needs a bulky electrolytic capacitor at the load side to buffer the double-frequency ripple power (DFRP), which reduces the reliability and power density significantly. This paper proposes a control method to divert the DFRP to the small energy transfer capacitor. Consequently, the bulky electrolytic capacitor is replaced with a small film capacitor. The proposed method is carried out by introducing the freewheel state (one switch is turned on and the other is turned off) into the control. So no extra hardware is added, which makes the proposed method cost-effective. A low electromagnetic interference emission is also achieved due to the continuous input–output currents. In addition, the proposed method can be extended to other topologies easily. This paper first gives the detailed analysis of the proposed control method, and then introduces the controller design. The selection of the passive components is also briefly discussed. Finally, the simulation and experimental results verify the effectiveness of the proposed control method. [ABSTRACT FROM AUTHOR]

These days, constant on-time current mode (COTCM) control scheme is widely used in the voltage regulator (VR) controllers because it has a higher light-load efficiency and a higher BW design capability while maintaining a simpler compensation requirement. One issue plaguing the COTCM control is its slow transient response which is caused by its fixed TON operation. During the heavy-load step-up transient, the duty cycle becomes saturated and the inductor current increment becomes limited by TON and the minimum off time (TOFF$\_$ MIN) ratio, which can create a large undershoot at load step up. On the other hand, in the load step-down case, if the load step down occurs at the beginning of TON, a large overshoot can be created at the output. To solve this issue, this paper presents a method designed to increase the TON at load step up and then very quickly, decrease at load step down in order to reduce the undershoot and overshoot at output or otherwise save the output capacitor. In this proposed method, the increase or decrease of T ON is proportional to the output change which eliminates the chance of any overcorrection or ring-back problem unlike the methods presented in prior forums. This feature enables the control to work seamlessly in a high-frequency load repetitive case in VR applications. Since this TON change occurs only in the transient period when duty cycle is saturated, it does not affect the small-signal property of the COT control. Moreover, the proposed methods are very much compatible with the state-of-the-art single and multiphase COT control structures. Simulation and test results in both single and multiphase operations are also presented in the paper to verify the proposed concept. [ABSTRACT FROM PUBLISHER]

This paper presents a design method for a resonant class-DE rectifier with a shunt inductance input network. The cass-DE resonant rectifier offers numerous advantages at high operating frequencies and high output voltages. For a high-voltage design, the limiting factor has been the absence of a design process incorporating shunt inductance for low-to-high impedance matching as well as nonlinear capacitance from semiconductor devices. To design a rectifier with a specific input impedance at the fundamental frequency of operation, designers have been relying on either parametric variation in iterative simulations that often takes a long time to complete, or simple equations without considering nonlinear capacitances that renders the analysis inaccurate at high frequencies. In this paper, we propose a design procedure that begins with universal design curves that are applicable regardless of the capacitance nonlinearity. This is followed by parameter selection and a convergence check to ensure the rectifier operates at the desired output voltage. Based on the outlined procedure, we design and experimentally verify a 27-MHz 350-V current-driven rectifier, a 25-MHz 500-V voltage-driven rectifier, and a 27.12-MHz 2-kV four-stage rectifier, all of which the resonant capacitor is nonlinear and the input impedance is resistive at the switching frequency. [ABSTRACT FROM PUBLISHER]

A novel soft-switching interleaved coupled-inductor boost converter is proposed in this paper. Only a single active soft-switching module is needed to simultaneously achieve the soft-switching property of the two switches in the interleaved coupled-inductor boost converter. The better efficiency is achieved with the less components and cost. The two main switches can achieve the ZVT turn-on and smaller-current turn-off simultaneously when the single active soft-switching module is active. Due to the coupling characteristic of the inductors, the voltages across the two inductors are changed at the same time; therefore, the equivalent circuit is equal to the parasitic capacitors of the two main switches in parallel to resonate with the auxiliary inductor. By coupling two input inductors, the volume and cost of the circuit can be reduced. The interleaved coupled-inductor topology can also reduce the input and output current ripples and share the input and output currents. The operating modes, analysis, and design of the proposed circuit have been discussed in this paper. Simulation and experiments are finally conducted to verify the validity of the proposed circuit. [ABSTRACT FROM PUBLISHER]

It is mandatory to keep the total harmonic distortion in the output of most inverters below the limits prescribed by different international standards. The harmonic distortions caused due to nonlinear loads may not get corrected by typical magnitude controller, like PID controller. Repetitive controller is more effective in such situations. Often, repetitive controller is used as add-on block to the conventional magnitude controller. Design of repetitive controller can be easily implemented on digital platform. Rapid change in phase and magnitude of inverter-filter's transfer function near corner frequency causes instability problems in repetitive controller. Various techniques have been proposed by researchers to overcome this problem. Most of the reported techniques rely on digital compensation. However, it is hard to find a digital compensator, which simultaneously meets the phase and gain requirements at moderate computational effort. Here, a new output voltage feedback scheme has been proposed, which simplifies the requirement of digital compensation. The proposed scheme requires an extra hardware but at negligible added cost. In spite of this extra hardware, the proposed circuit turns out to be more energy efficient in comparison to few popular schemes, reported in literature, where some resistance is introduced in the inverter's filter for better stability of controller. In addition to the proposed modification the paper presents a simplified explanation of the various factors affecting stability of repetitive controller. The paper also discusses a novel experimental method for verifying the efficacy of repetitive controller in suppressing distortion of any particular harmonic order. [ABSTRACT FROM PUBLISHER]

In this paper, a nonisolated dc–dc converter with high voltage gain is presented. Three diodes, three capacitors, an inductor, and a coupled inductor are employed in the presented converter. Since the inductor is connected to the input, the low input current ripple is achieved, which is important for tracking maximum power point of photovoltaic panels. The voltage stress across switch S is clamped by diode D 1 and capacitor C1. Therefore, a main switch with low on-resistance RDS (on) can be employed to reduce the conduction loss. Besides, the main switch is turned on under zero current. This reduces the switching loss. The steady-state analysis of the proposed converter is discussed in this paper. Finally, the proposed converter prototype circuit is implemented to justify the validity of the analysis. [ABSTRACT FROM PUBLISHER]

DC electric springs (DCES) are emerging technologies for the (i) regulation of mains voltage against the intermittent renewable generations and (ii) harmonic cancellation in dc microgrids. When conventional converter topologies (e.g., half-bridge or full-bridge converter) are adopted as DCES, the battery storage of the DCES has to process both the dc power and the ac harmonic power. The pulsating ac power can severely reduce the lifetime of the battery. To address this issue, a hybrid-DCES (H-DCES) is proposed in this paper to perform (i) and (ii) in a decoupled manner. With a modified topology and control method, the H-DCES can divert the ac current to the ground and retains the function of manipulating noncritical load for dc voltage regulation. The immediate benefits of this H-DCES are the reduction of storage capacity and a prolonged lifetime of the battery. Both the operating principle and the mathematical model of the proposed H-DCES are analyzed in this paper. A prototype of the H-DCES is practically tested in a 48-V dc grid. The experimental results show that the H-DCES can realize the decoupled operation of dc voltage regulation and harmonic cancellation. Simulation studies further demonstrate that the H-DCES requires less storage capacity than its counterparts. [ABSTRACT FROM AUTHOR]

This paper documents a new three-switch, isolated boost dc–dc converter. The major features of the proposed converter are as follows: 1) continuous input current; 2) reduced one active switch, one additional diode, and one additional capacitor; 3) unchanged primary and secondary voltage waveforms of the transformer when the duty cycle is changed; and 4) removal of the snubber circuit. This paper presents the operating principles, analysis, parameter design guidelines, and simulation results for the proposed converter. To verify the performance of the proposed converter, a 400 W prototype was constructed with a 40–60 V dc input. A PID controller was used to maintain the dc output voltage at 400 V. The simulation and experimental results matched those of the theoretical analysis. [ABSTRACT FROM AUTHOR]

Adjustable speed drive (ASD) and motors, if selected as a prime mover for compressors, pumps, extruders, etc., can provide various electromechanical benefits to its operators and stakeholders. Their benefits and application considerations have been well documented in past papers and tutorials. However, a successful installation of a multimegawatt motor and ASD system requires detailed application, engineering, manufacturing, testing, and installation considerations. Many times testing is requested by the operator and/or consultant, but navigating the types of tests available, test procedures, plans, and how they comply with appropriate standards is often not fully understood. This can lead to surprises, shipment delays, price adders, and ultimately the equipment itself not being in compliance with the stated project objectives. This paper attempts to address the factory acceptance testing phase of a medium voltage motor and ASD system whether procured separately or as a package. Issues such as type of test selection, specifications, standards, preparation, acceptance criteria, and finally string testing will be covered. This paper serves as a guideline of how one can select, prepare, witness, and sign off on a medium voltage motor and ASD test. [ABSTRACT FROM AUTHOR]

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

This paper investigates and evaluates the performance of a single-phase split-source inverter (SSI), where an alternative unidirectional dc–ac configuration is used. Such configuration is utilized in order to use two common-cathode diodes in a single device instead of using two separate diodes, resulting in minimum parasitic inductance in the commutation paths. In this paper, the analysis and modulation of the single-phase SSI using this alternative configuration is discussed, and the analysis of the low-frequency component in the dc side is introduced. Moreover, the features behind employing the triangular, the trailing-edge sawtooth, and the leading-edge sawtooth carriers with the single-phase SSI are discussed, and the differences among these carriers are highlighted. In order to highlight the performance of the proposed SSI, a comparative study is conducted with the two-stage architecture and the single-phase quasi-Z-source inverter (qZSI). The introduced analysis is enhanced with simulation results using MATLAB/PLECS models, where a 1-kVA single-phase SSI is designed and simulated. Finally, the designed 1-kVA single-phase SSI is implemented experimentally and tested at different operating points, i.e., at different voltage gains, and a maximum efficiency of $95.5\%$ is obtained. [ABSTRACT FROM PUBLISHER]

In order to match voltages between the fuel cell stacks and the DC link bus of fuel cell vehicles, a single-switch Boost dc–dc converter with diode-capacitor modules is proposed in this paper. The capacitors are charged in parallel and discharged in series. The wide voltage-gain range can be obtained by using a simple structure. In addition, the basic operating principles, the extended stages, the fault tolerant operation, and steady-state characteristics of the converter are analyzed and presented in this paper, and the small-signal model is also derived. A 400 V, 1.6 kW experimental prototype is developed, and the wide voltage-gain range (3.3 ∼ 8) is demonstrated with a maximum efficiency at 97.25%. The experimental results validate the effectiveness and feasibility of the proposed converter and its suitability as a power interface for fuel cell vehicles. [ABSTRACT FROM PUBLISHER]

The subject of this paper falls under the development of power electronics for more electric aircraft systems. The study concerns the design of a converter whose function is to generate a 300-V dc bus from a standard 28-V dc avionic network. Various systems, such as motor drives, need to be connected to the 28-V dc network. Their design could be simplified significantly, and standardized, by introducing this intermediate 28–300-V stage. The step-up converter in the proposed configuration is integrated as a part of the system. The power specification is 10 kW, which leads to very high-current values on the 28-V side. The choice of the converter topology, therefore, needs to match this central constraint. The proposed converter uses six boost cells, associated to constitute a series–parallel architecture. This arrangement leads to significantly more optimal sizing for high step-up ratios than conventional boost-cell configurations. Cell interconnection is implemented by means of a monolithic InterCell transformer to reduce the weight of the magnetic part. This paper describes the topology, design, and construction of the lab prototype, as well as experimental results obtained during testing. [ABSTRACT FROM PUBLISHER]

In high-power applications, parallel operation is required to improve both efficiency and reliability. In an LLC converter, it is difficult to achieve parallel operation due to the gain sensitivity to component tolerance. This paper proposes a new structure of a common resonant capacitor for a multiphase LLC converter, which can achieve very good current-sharing performance with no additional components or control. To evaluate the current-sharing performance, a new first harmonic approximation (FHA) model is built in this paper to analyze the LLC converter with coupled resonant tanks. Both FHA analysis and powersim (PSIM) simulation results demonstrate the load-sharing improvement of the proposed common capacitor LLC resonant converter over the conventional two-phase LLC converter. The current-sharing performance from the FHA analysis and the PSIM simulation are compared, and the error of the FHA analysis is evaluated and explained. A 600 W two-phase LLC converter prototype based on the proposed method is also built to verify the feasibility. Excellent current-sharing performance (6% resonant current sharing error at a wide load range) has been achieved. [ABSTRACT FROM PUBLISHER]

The demand on mobile electronics to continue to shrink in size while increasing in efficiency drives the demand on the internal passive components to do the same. Power amplifiers require inductors with small form factors, high quality factors ( Q\texts ), and high operating frequency in the single-digit gigahertz range. This paper explores the use of magnetic materials to satisfy the demands of power amplifier inductor applications. This paper then discusses the optimization choices regarding material selection, device design, and fabrication methodology. The inductors achieved here present the best performance to date for an integrated magnetic core inductor at high frequencies with a 1-nH inductance and peak $Q$ value of four at about 3 GHz. Such compact inductors show potential for efficiently meeting the need of mobile electronics in the future. [ABSTRACT FROM AUTHOR]

In this paper, a new zero voltage zero current transition (ZVZCT) boost DC–DC converter using a coupled inductor is proposed. This topology provides the main switch ZVZCT for the turn-on and zero voltage switching (ZVS) for the turn-off. Moreover, the auxiliary switch turns on at zero current switching (ZCS) and turns off at ZVS. The main diode turns on with ZVT and turns off with ZCS, and other diodes also operate under soft-switching conditions. Besides, due to the coupling effect, the proposed converter improves efficiency additionally since resonant energy in the resonance tank could be transferred to the output, and the circulating current can be limited as well. The soft-switching can be realized in almost all the load rang. In this design, there always exist energy releasing circuits to conduct magnetic flux leakage currents, such that the surge currents are eliminated and switch current stress can be accordingly reduced. All the devices resonate in a unique direction within less than half of a resonance period, so power losses with respect to the resonance can be decreased. In this paper, the converter design and operation principles of the converter are given. It also has been verified by a 1-kW experimental prototype with switching frequency of 100 kHz, and the related experimental results are presented. [ABSTRACT FROM PUBLISHER]

This paper presents the analysis and experiments of a variable inductor (VI) based LED driver for dc grid lighting applications. The proposed driver requires only a series inductor and a transformer as major components to drive the LED lamp from a half-bridge inverter. By introducing a VI as the series inductor, the LED current can be controlled independently from any other parameter, which makes it possible to drive and regulate several LED branches from the same half-bridge output. Other advantages of the proposed converter include inherent open-circuit and short-circuit protections, zero-voltage switching for the bridge transistor and zero-current switching for the output rectifier diodes, simple dynamics, possibility of analog and pulse width modulation dimming, constant switching frequency operation, and high efficiency. The converter is thoroughly analyzed and modeled for both steady-state and dynamic operation. As another novelty of this paper, the dynamic response of the VI has been studied and taken into account to obtain the complete transfer function of the VI-controlled system. In addition, some housekeeping issues that usually arise when dealing with VI, e.g., how to drive the VI bias winding, are solved in this work. Experimental results provided from a 50 W laboratory prototype demonstrate the correctness of the performed analysis and the good possibilities of the proposed converter. [ABSTRACT FROM PUBLISHER]

This paper presents a comparative study on different microfabricated inductors (microtransformers), which are suitable for high-frequency power application. The main topic of this study is comparing and analyzing the effect of some factors such as material type, number of turns, and coil form on microinductor performance considering a fixed chip size, fixed magnetic core size, and core form. Two different microtransformer designs with different magnetic core materials are considered in this work. The core materials used in this work are NiFe45/55 and CoFe45/55. Also, two types of device packages are developed, namely, Quad Flat No-Lead and FR4 embedded packages. For device testing, different high-frequency switching regulators available on the market are used. This study shows the influence of different parameters on the performance of a certain high-frequency application. In this paper, we discuss the influence of the design, magnetic material, and package type on thermal performance and the efficiency of the power application. [ABSTRACT FROM AUTHOR]