Leakage Inductance Research Articles

A High Step-Up Integrated Buck-Boost-Zeta Converter Using Three-Winding Coupled Inductor With Current Sharing Considered

This paper proposes a high-gain Buck-Boost-Zeta converter with three-winding coupled inductor, which is generated by differentially connecting the Buck-Boost converter and the Zeta converter and integrating the coupled inductor multiplier cell. An active switched-inductor is obtained at the input side by differential connection, which is used as the primary winding of the three-winding coupled inductor, and the multiplier cell is composed of the secondary winding and diode-capacitor. The diode-capacitor circuit in the topology is multiplexed as a passive clamp branch to absorb the leakage energy and the ZCS turn-on of the switches is achieved. Therefore, the proposed converter achieves higher voltage gain and lower switch voltage stress. At the same time, the proposed converter retains the continuous output current characteristic of the Zeta converter. The operation principles and performances of the proposed converter are analyzed in detail. Meanwhile, the imbalance currents of the primary windings caused by the leakage inductance error is analyzed and the coupled inductor current sharing method is given, which effectively alleviates the current pulsation of the primary winding. A 400W experimental prototype is built to verify the theoretical analysis.

Hybrid model to evaluate the frequency-dependent leakage inductance of partially-filled transformers

Hybrid model to evaluate the frequency-dependent leakage inductance of partially-filled transformers

Full Electromagnetic Integration of Impedance-Balanced EMI Filters for Single-Phase Power Converters

Utilizing passive electromagnetic interference (EMI) filters is the most widely used approach to restrain the conducted emissions from power converters. However, the introduction of these filters will significantly raise the weight and size of the systems. Using the emerging flexible multi-layer foil (FMLF) technique, this paper investigates a complete electromagnetically integrated design concept of single-phase EMI filters based on EE-type cores, which can be applicable to engineering application scenarios with different EMI noise attenuation requirements. Two types of integrated structures are constructed with different well-designed FMLF-windings and terminal configurations. One is a common-mode (CM) choke with controllable leakage inductances, which is able to realize the integration design of CM inductor, CM capacitors and differential-mode (DM) inductors. The other is an EMI choke with integrating the CM and DM inductances & capacitances, which achieves electromagnetic integration of all the CM and DM filtering components. Compared to the existing UU-type core based integration methods, the proposed methods can ameliorate the noise suppression performance while reducing filter's weight and volume. Theoretical analyses for modeling and design of the EMI chokes is presented. Then prototypes of different FMLFs based EMI filters have been built for a 500W 100kHz SiC-MOSFET inverter, experiments demonstrate the feasibility and validity of the proposed structures.

High Step-Up Soft-Switching DC–DC Converter Integrated With Y-Source Network

High step-up dc-dc converter is generally used in micro grid, uninterruptible power supply, hybrid electric vehicle, and other applications. For attaining high boosting and high efficiency, a high step-up soft switching circuit topology with an integrated Y-Source network is presented. Its front end is a Boost structure with the strengths of continuous and low ripple input current. The active clamp circuit may store the energy of leakage inductance in the output capacitor, and then output with reuse. In addition, the switches achieve zero voltage conduction, thereby decreasing its switching loss. At the same time, the coupling inductor achieves zero dc bias, which reduces the core size and core loss. The converter may attain high step-up by selecting the proper turns ratio of the coupling inductor at a reasonable duty cycle. The paper elucidates the working mode of the converter in depth, builds the small signal model, and study the stability of the converter. Finally, an experimental prototype of 200 W 28-380 V 100 kHz is built, and the feasibility of the presented converter is demonstrated in both dynamic and static aspects of the experiment.

A Novel High-Voltage-Gain Quasi-Resonant DC–DC Converter With Active-Clamp and Switched-Capacitor Techniques

We propose an isolated high-voltage-gain quasi-resonant dc-dc converter with a bi-functional circuit for the renewable energy applications. The proposed converter adopts an interleaved connection in the primary side, reducing input current ripple, and includes the bi-functional circuit operating as the switched-capacitor cells and two active-clamped circuits simultaneously. The converter realizes high voltage conversion ratio without using extreme duty ratio, and the voltage spike due to the leakage inductance of the isolation transformer is clamped. In addition, an output voltage doubler in the secondary side comprises a series resonant circuit and then obtains zero current switching (ZCS) turn-off of rectifying diodes; the diode reverse recovery problems are also alleviated. A 320W laboratory prototype that operates at input of 26 V-34 V and output of 400 V is fabricated to verify the effectiveness of the proposed converter.

A new adaptive dead time compensation method for dual three-phase permanent magnet synchronous motor

This paper proposes a new adaptive dead time compensation method for dual three-phase permanent magnet synchronous motors with two sets of three-phase windings spatially shifted by 30 electrical degrees. The stator resistance and leakage inductance are the only 5th and 7th harmonic impedances in the dual three-phase motor, which leads to a more pronounced current distortion due to dead time in the dual three-phase motor than in the three-phase motor. Therefore, dead-time compensation has significant implications for the application of dual three-phase motors. In this paper, the minimum value tracking algorithm is used to adjust the compensation voltage amplitude adaptively, and the compensation voltages are added to the output reference voltage in stationary frames. The proposed computation method has some significant advantages, such as simple implementation without additional hardware, easy mathematical computations, and no offline experimental measurements. Simulation results are provided to validate the performance of the proposed method.

Experimental analysis of phase shift modulation methods effects on EMI in dual active bridge DC-DC converter

Dual active bridge DC-DC converters (DAB) are one of the bidirectional converters and mainly used in electric vehicles and micro grids. With the increasing number of electric vehicles in use, and the increasing amount of batteries in these vehicles and rapidly spanning micro grids, the importance of DAB converters has increased and they are expected to be smaller in size and operate at higher power levels. The reduction in size has increased the importance of power density and efficiency, which are two significant parameters of DAB circuits. One of the methods to increase efficiency and power density is to increase the switching frequency. However, with the increase at the switching frequency, electromagnetic interference (EMI) in the DAB circuit also increases.In this manuscript, the change in the EMI values emitted by conduction, according to the phase shift modulation methods at DAB converters are evaluated. Also the effect of type of MOSFETs on conducted EMI is examined. Prototypes of the DAB converters by using Si and SiC MOSFETs with power rating of 1 kW are designed and developed. Switching frequency of converter is 25 kHz and leakage inductance is determined 81uH and 75uH. Si based circuit is operated with %88.5 efficiency. SiC based circuit is also operated with %88 efficiency. The designed circuits are operated using the phase shift modulations SPS and DPS. Conducted emission noise emitted by these circuits are analyzed by dividing them into common mode and difference mode noises. It has been observed that the EMI value when using SPS method is 15–20 dBµV lower than the EMI when using DPS method. The relationship between the measured noises and the efficiency of the circuits was observed.

Continuous pH monitoring using a sensor for the early detection of anastomotic leaks.

Anastomotic leaks (AL) and staple line leaks are a serious post-operative complication that can develop following bariatric surgery. The delay in the onset of symptoms following a leak usually results in reactive diagnostics and treatment, leading to increased patient morbidity and mortality, and a clinical and economic burden on both the patient and the hospital. Despite support in literature for pH as a biomarker for early detection of AL, the current methods of pH detection require significant clinician involvement and resources. Presented here is a polyaniline (PANI)-based pH sensor that can be connected inline to surgical drains to continuously monitor peritoneal secretion in real time for homeostatic changes in pH. During this study, the baseline peritoneal fluid pH was measured in two pigs using the PANI sensor and verified using a benchtop pH probe. The PANI sensor was then utilized to continuously monitor the changes in the pH of peritoneal effluent, as a gastric leak was simulated. The inline sensors were able to detect the resulting local changes in drainage pH within 10 min of leak induction. The successful implementation of this sensor in clinical practice can both enable high efficiency continuous monitoring of patient status and drastically decrease the time required to detect AL, thus potentially decreasing the clinical and economic burden incurred by gastric leaks.

Analysis and Design of a New High Voltage Gain Interleaved DC–DC Converter with Three-Winding Coupled Inductors for Renewable Energy Systems

In this article, a new non-isolated interleaved DC–DC converter is proposed to provide a high voltage conversion ratio in renewable energy systems. The converter configuration is composed of a two-phase interleaved boost converter integrating a voltage-lift capacitor and three-winding coupled inductor-based voltage multiplier modules to achieve high step-up voltage conversion and reduce voltage stresses on the semiconductors (switches and diodes). The converter can achieve a high voltage conversion ratio when working at a proper duty ratio. The voltage stresses on the switches are significantly lower than the output voltage, which enables engineers to adopt low-voltage-rating MOSFETs with low on-state resistance. The switches can turn on under zero-current switching (ZCS) conditions because of the leakage inductor series reducing switching losses. Some diodes can naturally turn off under ZCS conditions to alleviate the reverse–recovery issue and to reduce reverse–recovery losses. The input current has small ripples due to the interleaved operation. The leakage inductor energy is recycled and voltage spikes on the switches are avoided. The proposed converter is suitable for applications in which high voltage gain, high efficiency and high power are required. The principle of operation, steady-state analysis and design considerations of the proposed converter are described in detail. In addition, a closed-loop controller is designed to reduce the effect of input voltage fluctuation and load change on the output voltage. Finally, a 1000 W laboratory prototype is built and tested. The theoretical analysis and the performance of the proposed converter were validated by the experimental results.

Applying a Multiple-Input Single-Output Interleaved High Step-Up Converter with a Current-Sharing Device Having Different Input Currents to Harvest Energy from Multiple Heat Sources

In this paper, a thermoelectric conversion system for multiple heat sources is proposed. For design convenience, the overall system employs only a single-stage converter. Such a converter uses coupling inductors and switched capacitors to increase the voltage gain. In order to reduce the high-frequency voltage oscillation of the turn-off of the main switches created from leakage inductors, two active clamp circuits with zero voltage switching (ZVS) turn-on are employed. By doing so, although the current-sharing device with interleave control is embedded in the proposed converter, the input currents can be unequal. Therefore, the inputs of the converter can operate under individual maximum power points and transfer the energy from different thermoelectric generators (TGs) to a single load. Furthermore, the main switches have low voltage stress during the turn-off period. As for the maximum power point tracking (MPPT) method, it utilizes a three-point-weighting method to improve the tracking stability. In addition, the number of inputs of this converter can be extended. The MPPT simulation is presented to verify the feasibility as well as several experimental waveforms to demonstrate the effectiveness. The field programmable gate array (FPGA) is used as a digital control kernel to control the thermoelectric conversion system.

A Design Method of Partially Interleaved Winding Structure With Low Leakage Inductance for Planar Transformer Application

For the planar transformer with turns ratio away from 1:1, the leakage inductance of fully interleaved winding structure is not the minimal and the structure should be optimized. In this paper, a design method for partially interleaved winding structure is proposed to achieve the minimal leakage inductance at arbitrary turns ratio. According to the analysis of magnetomotive force (MMF), the tradeoff among the total number of layers, the number and the position of consecutive primary-side layers will be executed through the recursive design flow to minimize the leakage inductance. Based on this design method, the optimal partially interleaved structures for the transformers with 16:12 turns ratio and 25:3 turns ratio are “(P-S-P-S-P-S-P) <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> ” and “5P-S-5P-S-5P-5P-S-5P”, respectively, and the leakage inductances are verified by the finite element analysis (FEA) and the experiment data. For the proposed structure, the measured leakage inductance drops 50%, and its dependence of frequency and the series resistance also decrease compared to the fully interleaved structure. Furthermore, the transformers with the proposed structures were tested in an LLC converter, where the loss of the converter and the change of resonant frequency are the smallest compared to other structures.

Design and Implementation of a High Step-Up DC-DC Converter with Active Switched Inductor and Coupled Inductor

In this paper, a high step-up dc-dc converter is presented. The proposed converter features a with high voltage conversion ratio and high efficiency with a reasonable duty cycle by adopting an active switched inductor and a coupled inductor. The voltage stresses on the power switches are lower, and with the energy stored in the leakage inductor being recycled, its efficiency is improved. Moreover, current stresses of the power switches are greatly reduced as caused by inductors parallel charging and series discharging on the active switched inductor. Loss analyses of its components are also presented. A comparison including component counts, voltage gain and voltage stresses of power switches with other relevant converters are analyzed. Eventually, a laboratory prototype with an input voltage of 24 V-36 V and an output voltage of 400 V with 400 W rated power is implemented to validate the correctness and effectiveness of the theoretical analyses.

Zero-Loss Switching in $LLC$ Resonant Converters Under Discontinuous Conduction Mode: Analysis and Design Methodology

Many thriving applications where isolation is required, such as LED drivers, traction and EV fast charging, implement <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converters, particularly when voltage regulation is not required or an additional conversion stage is in charge of it. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter can be operated under discontinuous conduction mode (DCM), due to its advantages such as unregulated and sensorless operation, fixed switching frequency and voltage gain, and zero-current switching (ZCS). However, ZCS results in EMI and switching losses in the primary converter, particularly for ≥1200-V devices. Alternatively, zero-loss switching (ZLS) can be accomplished by means of a proper design of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter, overcoming the drawbacks of ZCS. The focus of this paper is to perform an exhaustive research on the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter under DCM-ZLS: discontinuous conduction mode with lossless switching in the primary and secondary sides. As a result of this analysis, a set of design boundaries are deduced for parameters such as the magnetizing inductance, the leakage inductance, and the gate resistance. A comprehensive, step-by-step design methodology is proposed and applied to a 18-kW, 200-kHz test bench. The designed parameters are implemented in the converter and several experiments are conducted, including a test at rated input voltage and rated power (600 V, 18 kW). The conduction states studied theoretically in the analysis of the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter are identified in the experimental results, and the operation of the test bench under DCM-ZLS is verified.

Fully-Integrated Transformer With Asymmetric Primary and Secondary Leakage Inductances for a Bidirectional Resonant Converter

Typically, inserted-shunt integrated transformers have symmetric primary and secondary leakage inductances. However, bidirectional resonant converters typically operate more efficiently with different primary and secondary series inductances. In this paper, a new topology for an inserted-shunt integrated transformer which can provide tunable, asymmetric leakage (series) inductances on the primary and secondary sides is presented. Two magnetic shunts, with appropriate air gaps, are inserted between two E-cores and the primary and secondary windings are separated by being placed at opposite sides of the shunts. The proposed transformer is analysed in detail and modelling and design guidelines are provided. It is shown that the magnetising inductance and the primary and secondary leakage inductances are decoupled from each other, and they can be determined separately. The design has the advantage of using planar E-cores and magnetically permeable sheets that are commercially available. The theoretical analysis is verified by simulation and experimental results. In addition, to demonstrate the performance of the proposed integrated transformer in practice, an exemplar bidirectional CLLLC resonant converter is designed, constructed and tested using the new integrated transformer.

An Interleaved High Step-Up DC/DC Converter-Based Three-Winding Coupled Inductors With Symmetrical Structure

This paper proposes an interleaved high step-up converter based on three-winding coupled inductor (TW-CI) with symmetrical structure. By utilizing the TW-CI along with a voltage multiplier cell, the proposed converter achieves high power transfer ability as well as minimized voltage stress across power switches and diodes. The converter has significantly improved the voltage gain by integrating two TW-CIs with the passive clamp circuit. The leakage inductor energy of the TW-CI is recycled to improve the voltage gain and efficiency while facilitating the soft switching condition for the power switches. Additionally, the voltage stress across the power switches is decreased with the help of the clamping capacitors. Therefore, low-voltage-rated semiconductors with small on-resistance can be chosen which reduce conduction losses and improve the overall performance. Moreover, two series-connected capacitors of the primary side are introduced, which effectively balance the voltage between the power switches and the capacitors during steady and dynamic states. Finally, a 400W experimental prototype with 24V-400V is built to is verify the accuracy of proposed converter.

Design Trade-Off Between Torque Density and Power Factor in Surface-Mounted PM Vernier Machines Through Closed-Form Per-Unit Equations

Benefited from flux modulation effects, surface-mounted permanent magnet vernier machines (SPMVMs) present the high-torque low-speed properties, which can become the potential candidates for direct-drive applications. However, their power factor is inferior to conventional PM machines due to the large inductance caused by parasitic no-working harmonics. This paper is devoted to propose some design considerations of SPMVMs to make a good compromise between torque density and power factor. Via constructing closed-from per-unit equations, the cross-coupling influences of slot/pole combinations and normalized geometric variables on machine performances are revealed. It is found that there is a tradeoff between torque density and power factor. The high magnet thickness to air-gap length ratio is beneficial to decrease inductance, while the flux modulation effect under the large equivalent air-gap length would be impaired. Moreover, the pole-pair ratio, i.e., the PM pole-pair to armature winding pole-pair, should be carefully selected, where the SPMVMs with high pole-pair ratio have the relatively high magnetic loading owing to the strong flux modulation effects, whereas they suffer from the low power factor due to serious harmonic leakage inductance. In particular, taking the end-winding length into consideration, the high torque advantages of high pole-pair ratio SPMVMs under the same copper losses can be well performed with high length-radius ratio. Combined with the analysis, the preferable selections of critical parameters to satisfy various technical indexes are determined. Then, the general design approach is proposed, and two design examples are built and compared. Meanwhile, finite element analysis (FEA) and prototype experiments are carried out to verify the feasibility.

High Gain Magnetically Coupled Single Switch Quadratic Modified SEPIC DC-DC Converter

This article proposes, analyzes, and tests an improved high voltage gain dc-dc converter based on a single-ended primary-inductor converter (SEPIC). The proposed magnetically coupled quadratic modified SEPIC converter (MCQ-MSC) employs a coupled transformer with an optimized design to obtain a high voltage boost factor by controlling the transformer's turn ratio along with the switching duty cycle. Thanks to the unique structure of the coupled transformer, high voltage gain is obtained at low turns ratio, which is highly desirable for high voltage applications and the compact size of the converter. In addition to the coupled transformer, a voltage-boosting module is utilized to achieve a very high output voltage for a low switching duty cycle. The proposed inverter has a single switch with a wide control range of duty cycle (0<D<1), causing low conducting losses and high efficiency. Furthermore, a clamping circuit is successfully designed to remove the leakage inductance effects of the coupled transformer on the power switch. The proposed MCQ-MSC drains a continuous current from the input dc source, which makes it a suitable choice for renewable energy sources (RES). The hardware prototype of the proposed converter is tested to verify the mathematical expressions and theoretical results.

Design and Optimization of an Integrated Resonant Inductor With High-Frequency Transformer for Wide Gain Range DC–DC Resonant Converters in Electric Vehicle Charging Applications

Large-scale adoption of wide band gap semiconductors in switched mode power converters enables miniaturization of power electronic systems. With switching frequencies approaching a few hundred kilohertz - megahertz range, efficient and compact design of magnetic components are crucial for future generation power supplies in data centers or electric vehicle (EV) applications. In a typical two-stage AC-DC power supply, the DC-DC stage is often constructed using a resonant converter with galvanic isolation provided by a high-frequency transformer. In such systems, the integration of an inductor in the resonant network with the transformer helps improve power density and reduces component count and cost. However, the integration of magnetic components can result in increased losses, deteriorating the performance of the power conversion system. In this paper, a magnetic structure along with an optimization methodology is presented to integrate a predefined resonant inductor as leakage inductance of the high-frequency transformer achieving minimum penalty on converter efficiency using planar core geometry and printed circuit board (PCB) based windings. The proposed methodology is applied to integrate a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$7.8 \mu \rm{H}$</tex-math></inline-formula> inductor with a 2:1 transformer for a 6.6 kW, 500 kHz LCL-T resonant DC-DC stage utilizing GaN transistors in an onboard battery charging converter. On the prototype converter using the optimized integrated magnetic component, a peak efficiency of 98.4% was obtained using PCB windings. Furthermore, the integrated magnetic component achieved 64 kW/L power density in the demonstrator prototype.

A Soft-Switched Current-Fed Dual-Input Isolated DC–DC Converter Topology

A soft-switched current-fed dual-input isolated dc-dc converter topology is proposed in this article. This converter integrates two low-voltage dc sources with similar transferred characteristics such as two PV panels or two batteries into a dc bus using a simple circuit topology and a minimum number of active and passive components. The energy transfer between the input and output ports is controlled by modulating the pulse-width of the control signals. Moreover, the soft-switching operations are discussed, and the smooth connection between the input-side inductor and the transformer leakage inductance is achieved. Furthermore, the operation of the converter in reverse power flow direction is presented to demonstrate the bidirectional operational capability of the converter. Finally, different operation modes of the proposed dual-input converter are verified by the experimental results obtained from a 250 W hardware prototype.

Accurate Leakage Inductance Modeling Using an Artificial Neural Network Based on the Dowell Model

Accurate Leakage Inductance Modeling Using an Artificial Neural Network Based on the Dowell Model