Inductor Volume Research Articles

A Novel Hybrid LDC Converter Topology for the Integrated On-Board Charger of Electric Vehicles

Recently, the integrated On-Board Charger (OBC) combining an OBC converter with a Low-Voltage DC/DC Converter (LDC) has been considered to reduce the size, weight and cost of DC-DC converters in the EV system. This paper proposes a new integrated OBC converter with V2G (Vehicle-to-Grid) and auxiliary battery charge functions. In the proposed integrated OBC converter, the OBC converter is composed of a bidirectional full-bridge converter with an active clamp circuit and a hybrid LDC converter with a Phase-Shift Full-Bridge (PSFB) converter and a forward converter. ZVS for all primary switches and nearly ZCS for the lagging switches can be achieved for all the operating conditions. In the secondary side of the proposed LDC converter, an additional circuit composed of a capacitor and two diodes is employed to clamp the oscillation voltage across rectifier diodes and to eliminate the circulating current. Since the output capacitor of the forward converter is connected in series with the output capacitor of the auxiliary battery charger, the energy from the propulsion battery can be delivered to the auxiliary battery during the freewheeling interval and it helps reduce the current ripple of the output inductor, leading to a smaller volume of the output inductor. A 1 kW prototype converter is implemented to verify the performance of the proposed topology. The maximum efficiency of the proposed converter achieved by the experiments is 96%.

Nonlinear Stabilization Controller for the Boost Converter with a Constant Power Load in Both Continuous and Discontinuous Conduction Modes.

The operation of Boost converters in discontinuous conduction mode (DCM) is suitable for many applications due to the, among other advantages, inductor volume reduction, high efficiency, paralleling, and low cost. Uses in biomedicine, nano/microelectromechanical, and higher power systems, where wide ranges of input/output voltage and a constant power load (CPL) can coexist, are well-known examples. Under extremely wide operating ranges, it is not difficult to change to a continuous conduction mode (CCM) operation, and instability, chaos, or bifurcations phenomena can occur regardless of the conduction mode. Unfortunately, existing control strategies consider a single conduction mode or linearized models because only slight resistive/CPL power level or input/output voltage variations (and no conduction mode changes) were expected. In this paper, new mathematical models for the Boost converter (with resistive or CPL) that are conduction mode independent are presented and validated. Since the open-loop dynamics of the proposed CPL model is unstable, a nonlinear control law capable of stabilizing the boost converter regardless of the conduction mode is proposed. A stability analysis based on a common-Lyapunov function is provided, and numerical and experimental tests are presented to show the proposal’s effectiveness.

Interleaved Bidirectional Chopper With Auxiliary Converters for DC Electric Railways

This article presents an interleaved bidirectional chopper with auxiliary converters for onboard energy storage systems that is capable of achieving a significant reduction in the mass and volume of the current-smoothing inductors. The proposed chopper consists of multiple interleaved subconverters, where each subconverter consists of a bidirectional chopper cell, a current-smoothing inductor at the low-voltage side, and an auxiliary converter that is formed by the cascade connection of multiple full-bridge cells. Each auxiliary converter is connected in series with its respective inductor to suppress the ac voltage component that produces ripple current in the inductor of each subconverter; hence, a smaller inductor can be used to meet the ripple current requirement when compared with the conventional bidirectional chopper. In addition, auxiliary converters can be used as dc-circuit breakers to protect the low-voltage side against faults in the power devices of the bidirectional chopper cells. This article discusses the operating principles and control method of the proposed chopper, followed by experiments using a downscaled experimental model.

A Family of High Step-Up Quasi Z-Source Inverters with Coupled Inductor

With the continuous development of new energy, there is more and more research on step-up inverters in photovoltaic and wind power generation systems. The Z-source inverter has become a research hotspot because of its small output THD (Total Harmonic Distortion) and high reliability. However, the traditional Z-source inverters cannot meet the higher boost requirements of new energy power generation. The quasi-z-source inverter with stronger boosting ability came into being. The high step-up Z-source inverters presented in existing literature is only focused on one or several topologies and lacks a comparative analysis on different topologies. Based on the quasi-Z-source inverter, this paper proposes a family of quasi-z-source inverters with a coupled inductor. The required voltage gain can be obtained by changing the turns ratio of the coupled inductor, which provides a new control variable for the system and makes the design of the system becomes more flexible. Through the analysis and comparison of each topology in terms of boost capacity, voltage stress, coupled inductor volume, circuit efficiency, and input ripple, the characteristics of each topology are summarized. The representative topology was simulated and analyzed, and a 1 kVA prototype was developed in the laboratory to verify the correctness of the theoretical analysis.

Design Method of PCB Inductors for High-Frequency GaN Converters

The new power Gallium Nitride transistors allow to increase the operating frequency of converters to megahertz range, thanks to their low switching time that is of a few nanoseconds or less. This permits to reduce the values and the volume of the passive components, and enhance the power density of power converters. However, inductors needed for energy storage still take a large volume in converters compared with the others components, because of their weak energy density. Furthermore, high-frequency operation require low-losses magnetic materials. In this article, a design method of PCB inductors is proposed. A flexible ferrite sheet is used to enhance the inductance value and ease the realization of custom-shape devices. The design method of the inductor is based on the optimization of the inductor volume taking into account thermal issues of the magnetic sheets. Also a simulation method is proposed to calculate the equivalent stray capacitance of the inductors. The proposed method provides a losses volume tradeoff that helps designers to optimize the inductor for their application.

Variable-Frequency Critical Soft-Switching of Wide-Bandgap Devices for Efficient High-Frequency Nonisolated DC-DC Converters

This paper derives a variable-frequency critical soft-switching control method for nonisolated DC/DC converters using wide-bandgap devices. The critical soft switching control technique under maximum frequency trajectory is introduced to maintain zero voltage switching over a wide range of modulation ratios according to the load variation. The concept prevents turn-on losses that are typically much larger than the turn-off losses in SiC and GaN FETs and the latter can be further reduced by adding external drain-source capacitors. We have derived the boundary conditions for critical soft switching operation. For the reduction of inductor value and volume, a maximum available switching frequency is applied to the converter within the constraints of device requirement and soft switching boundary conditions. We demonstrate experimentally that the proposed concept reduces the power losses in the wide-bandgap devices by a factor of approximately 3, enables an increase of the switching frequency by a factor of about 5, and a decrease of the main inductance by a factor of about 10. Then variable frequency critical soft switching control method is proposed with the constraints to maintain the maximum frequency within soft switching operation. Since our test bench uses off-the-shelf inductors, the inductors are subject to significant high frequency losses. Despite this, the converter efficiency increases by 1%.

Dual-Buck Full-Bridge Converter With Soft-Switching Characteristics for High-Precision Applications

The output distortion of conventional full-bridge inverter is present due to the required switch blanking time. Dual-buck full-bridge inverter (DBFBI) does not experience blanking time problems but requires a bias current to make the inductors operate in continuous conduction mode (CCM) for better output waveform with interleaved switching. The existence of bias current will cause dc-biased magnetization of the inductors and make them easy to saturate. To overcome this problem, the volume of inductors must be sufficiently large to ensure that there is no saturation in CCM of inductors’ operation. This article proposes extra snubber cells to realize soft-switching operation of the converter. The extra snubber cell DBFBI (ESCDBFBI) topology has the advantages of high-precision current output and much lower total inductor volume. The basic operation and properties of the ESCDBFBI topology are explained. Finally, an 800-W prototype of the proposed inverter is built and the experimental results agree with the theoretical analysis.

Reduction of harmonic current distortion for single‐phase grid‐tied inverter operated in discontinuous current mode

AbstractDiscontinuous current mode (DCM) with high‐frequency operation can be an effective way to reduce the volume of inductors for low‐power grid‐tied inverter applications. Unlike the controllers designed for continuous current mode operations, current controllers for DCM are required to address their nonlinear characteristics. A feed‐forward controller can be a good choice for the current control of the grid‐tied inverters operated in DCM. However, distortions in the output current cannot be eliminated, and they can be more severe if devices with large output capacitance are applied. Two harmonic current reduction strategies, namely a partial feedback path and an improved modulation, are proposed to reduce the low‐ and high‐order harmonics for single‐phase grid‐tied inverters operated in DCM. The proposed strategies are discussed and verified by a laboratory prototype in some experiments. It is indicated that the proposed modulation can mitigate the influence of device parasitic capacitance on current distortion and expand the device selections. © 2020 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Innovative Production of Biosurfactant by Candida Tropicalis Ucp 1613 Through Solid-state Fermentation

Microbial surfactants are amphipathic molecules mainly produced by submerged fermentation, and capable of decreasing the surface and interfacial tension between two immiscible phases. However, their obtention by solid state fermentation (SSF) has gained attention due to the less complex equipment involved, less energy demand, low volumes of water and requirement of less solvent for extraction. Hence, the aim of this study was to evaluate the ability of Candida tropicalis UCP 1613 to produce biosurfactant through solid-state fermentation and determine its stability under different environmental conditions. A factorial design 24 was performed to determine the influence of four variables, which were inoculum size, temperature, and particle size and inductor volume on the surface tension. In addition, the stability of the biomolecule was analysed in different pH, temperature and salinity ranges. The results showed that yeast synthesized biosurfactant under all conditions tested. From the statistical analysis, it was bserved that all variables except the inductor concentration had a significant influence on the surface tension decrease. The lowest value 25.8 mN/m was detected at condition 8 (10-6 cells/mL; 31 °C; 32 mesh and 0 mL of the inductor). The biosurfactant displayed a good performance when analysing its activity in different temperature, salinity and pH ranges. The study showed the feasibility of the solid-state fermentation to obtain a biosurfactant with excellent activity produced by a yeast. At the same time this is the first report of its kind in the literature.

Characteristic analysis of inductor in pulsed power supply changing with shape ratio

Solenoid inductor is an important component of pulse power source, its volume, electrical performance, stress and magnetic field generated during discharge directly affect the relevant parameters and performance of pulse power source. This paper presents a calculation model for solenoid inductor in pulsed power supply, given the inductance value and the wire, the volume, stress, resistance and external magnetic intensity of the five inductance values inductor under different shape ratio are calculated by changing the number of turns, and discusses and analyzes the changes and extremum in the volume, resistance, stress, and magnetic intensity of inductor with shape ratio. This article has certain guiding significance for the design of solenoid inductors.

Feasibility Study of Interleaving Approach for Quasi-Z-Source Inverter

This paper presents a comprehensive feasibility study of an interleaving approach for a quasi-Z-source inverter. The state-of-the-art approach revealed that an interleaving approach is often used to improve the efficiency and power density that can overcome the problem of oversized passive elements of quasi-Z-source-based converters. The focus is on the application of the interleaving approach in terms of the comparison of several important parameters of a quasi-Z-source inverter. Our analysis includes losses, capacitor and inductor sizes, as well as semiconductor costs. The theoretical comparison is based on the quasi-Z-source inverter model and the losses model. Simulation and experimental verification of theoretical statements are provided. It was found that a 40% reduction of inductor volume, along with 15–20% of efficiency improvements, are achievable. The results are discussed in the conclusion.

GaN‐based split phase transformer‐less PV inverter with auxiliary ZVT circuit

This paper explores performance enhancement of the common ground dynamic dc-link (CGDL) inverter for single phase photovoltaic (PV) applications by a combination of gallium nitride (GaN) devices, split phase topology, coupled inductors, and zero voltage transition (ZVT) scheme. The CGDL inverter has the inherent advantage of minimised dc-link capacitance and negligible leakage current due to the common ground configuration, but its reported efficiency was usually lower because of the higher dc-link voltage used for the reduction of decoupling capacitance to a great extent. To solve the efficiency problem, in this study, a soft switching circuit is proposed for the first stage, while a coupled inductor integrated magnetics is incorporated in the second stage to reduce inductor loss, volume, and cost. Both of these topological improvements combined with the use of GaN devices facilitate in achieving high efficiency without compromising converter power density. Extensive experimental results are provided from a GaN based 1 kVA hardware prototype to demonstrate the superior performance of the CGDL inverter attaining a peak efficiency of 98.7% and a California Energy Commission efficiency of 98.5% at 75/50 kHz switching frequency.

Analytical Derivation and Design of 20-MHz DC–DC Soft-Switching Resonant Converter

In this article, a novel 20-MHz high-frequency high-performance dc-dc resonant converter is analyzed, which owns the characteristics of soft-switching, low voltage stress, and small volume. The numerical analysis is conducted in time domain and the resonant parameters can be accurately calculated based on the corresponding expressions. A full resonant rectifier stage is adopted without using choke inductors, and the value and volume of inductors can be greatly reduced. A 12-V input, 5 V/5 W output prototype is proposed in the laboratory and the experimental results verify the feasibility of the proposed converter and numerical design methodology.

Novel ZVS S-TCM Modulation of Three-Phase AC/DC Converters

For three-phase AC-DC power conversion, the widely-used continuous current mode (CCM) modulation scheme results in relatively high semiconductor losses from hard-switching each device during half of the mains cycle. Triangular current mode (TCM) modulation, where the inductor current reverses polarity before turn-off, achieves zero-voltage-switching (ZVS) but at the expense of a wide switching frequency variation (15× for the three-phase design considered here), complicating filter design and compliance with EMI regulations. In this paper, we propose a new modulation scheme, sinusoidal triangular current mode (S-TCM), that achieves soft-switching, keeps the maximum switching frequency below the 150 kHz EMI regulatory band, and limits the switching frequency variation to only 3×. Under S-TCM, three specific modulation schemes are analyzed, and a loss-optimized weighting of the current bands across load is identified. The 2.2 kW S-TCM phase-leg hardware demonstrator achieves 99.7% semiconductor efficiency, with the semiconductor losses accurately analytically estimated within 10% (0.3 W). Relative to a CCM design, the required filter inductance is 6× lower, the inductor volume is 37% smaller, and the semiconductor losses are 55% smaller for a simultaneous improvement in power density and efficiency.

Evaluation of high power density achievement of optimum 4‐level capacitor‐clamped DC–DC boost converter with passive lossless snubber circuit by using Pareto‐Front method

This study presents the evaluation of the proposed optimum 4-level capacitor-clamped DC-DC boost converter (CCBC) for high power density achievement by using Pareto-Front method. The 4-level CCBC with considering high switching frequency can greatly reduce the inductor size and volume. High switching frequency caused the switching devices to suffer high semiconductor losses. Consequently, the cooling device volume is increased as well. Thus, this study presents soft-switching technique in the 4-level CCBC for semiconductor losses reduction. The combination of optimum design of inductor, improvement of circuit structure and soft-switching technique may lead to the highest power density of the converter. A 400 W of the 4-level CCBC converter is designed and experimentally verified. The results show that the inductance and inductor volume required in the 4-level CCBC is reduced by 88.89 and 80.75%, respectively. Besides, Pareto-Front curve shows the highest power density of soft-switching technique with the proposed 4-level CCBC is 6.51 kW/dm 3 at 800 kHz of switching frequency with efficiency of 97.20%.

Single-Phase AC–DC Converter With SiC Power Pulsation Buffer for Pulse Load Applications

Single-phase ac–dc converter for low-frequency pulse load normally requires high-capacitance electrolytic capacitors, which reduces the lifetime and may cause reliability problem. To meet the challenges of voltage ripple, this article introduces a power pulsation buffer (PPB) that smooths the output voltage and provides essential pulse power to the load simultaneously. The proposed PPB is realized by a discontinuous current mode (DCM) bidirectional buck/boost converter with real-time duty-cycle calculation (RDC) and peak voltage control. The proposed control method can relieve the capacitance requirement and achieve good dynamic response. The electrolytic capacitor is replaced with the film capacitor which has better reliability. SiC devices are adopted to further reduce the inductor volume of PPB. The core-less design is also proposed to design an integrated air-core inductor for further volume deduction. To meet the DCM requirement of PPB in various operating conditions, the phase shift between the line voltage and pulse load is taken into account. An electrolytic capacitor-less prototype with 1800-W peak power is built to verify the advantages of the proposed method.

Study on a Three-Phase Inductor Based on Equal Magnetic Flux Path

Owing to a uniform air-gap distribution of the magnetic powder materials, it is found that the conventional structure of a three-phase inductor made of magnetic powder cores will cause the three-phase magnetic flux paths to be unequal, thereby making the three-phase input voltages of a pulsewidth modulation (PWM) rectifier imbalanced. This paper presents a novel magnetic powder core structure applicable to a three-phase inductor for PWM rectifier. An equal magnetic flux path for the inductor core is designed to solve the imbalance problem of three-phase voltages. The proposed design is based on measuring the maximum flux density and the inductance values, modeled with electromagnetic simulation of a three-dimensional finite-element method. Simulation and experimental results of the proposed design show that it reduces the three-phase voltage imbalance to less than 3%. Furthermore, the unit volume of the three-phase inductor is reduced by 34% and 23%, and the efficiency is increased by 1.2% and 0.9%, compared to those of a conventional three-phase silicon-steel core inductor and three single-phase inductors, respectively.

Half-Bridge Integrated Phase-Shifted Full-Bridge Converter With High Efficiency Using Center-Tapped Clamp Circuit for Battery Charging Systems in Electric Vehicles

In this article, a half-bridge (HB) integrated phase-shifted full-bridge (PSFB) converter with a new center-tapped clamp circuit is proposed to achieve high efficiency in electric vehicle battery charging systems. The proposed converter has the benefits of HB integrated PSFB converters, such as the extended zero-voltage-switching range and the reduced conduction loss on the primary side. In addition, by using a new center-tapped clamp circuit, which consists of two diodes and one capacitor, the proposed converter can solve the drawbacks of conventional PSFB converters, such as the substantial circulating current, the severe voltage stress and switching loss in the secondary full-bridge rectifier, and a large output inductor. With these improvements, the efficiency is fairly increased, and the volume of the output inductor is reduced. In order to validate the feasibility of the proposed converter, a 3.3-kW prototype was built and tested.

A Voltage-Edge-Rate-Limiting Soft-Switching Inverter Based on Auxiliary Resonant Pole

To increase switching frequencies while limiting switching losses in voltage-source inverters, power switches have been made significantly faster with achievable switching times now less than 100 ns. However, faster switches generate larger inverter output voltage edge rates ( ${dv/dt} $ ) and result in deleterious effects in variable-speed drive systems including transient overvoltages at motor terminals, electromagnetic interference, and bearing failures due to microarcs. A common approach for limiting peak ${dv/dt} $ involves using a ${dv/dt} $ filter. However, the ${dv/dt} $ filter introduces extra power losses and increases the overall size and weight of the system. Soft-switching circuits, which were originally developed to reduce switching losses, can help reduce ${dv/dt} $ , but using soft-switching to accurately control ${dv/dt} $ has not been fully explored. In this paper, a new soft-switching circuit, entitled the auxiliary resonant soft-edge pole (ARSEP), is set forth. ARSEP improves the available soft-switching circuits so that ${dv/dt} $ can be accurately controlled through the circuit parameter design. An ARSEP inverter prototype was designed, simulated, and constructed to verify its performance and benefits. Compared to a conventional hard-switched inverter with a ${dv/dt} $ filter, the ARSEP inverter prototype results in a significant reduction in overall power loss, inductor volume, and weight.

Modeling and Design of the Magnetic Integration of Single- and Multi-Stage EMI Filters

A magnetic integration method of single- and multi-stage electromagnetic interference (EMI) filters is presented. Common-mode and differential-mode inductors are integrated into a single magnetic core unit to significantly reduce the filter volume. A 500-W silicon carbon (SiC) single-phase inverter is used as an experimental platform. The magnetic integration model is designed, and the magnetic circuit analysis is conducted in a simulation to ensure that the core will not reach magnetic saturation under full-load conditions. The feasibility of the proposed method is verified by an EMI test in a simulation and an experiment. Compared with a traditional discrete passive EMI filter, the proposed integrated EMI filters can reduce 40% of the total volume and 69% of the inductor volume in an integrated single-stage EMI filter with satisfactory EMI suppression ability. Although the weight of integrated inductor of integrated multi-stage EMI filter (IMSEF) has 23.8% increment, the IMSEF shows a better EMI suppression ability and 4.6% inductor volume reduction.