Leakage Inductance Research Articles

Modeling and Optimal Design of Magnetic Drive for High‐Voltage Nanosecond Marx Generator

All‐solid‐state high‐voltage pulse generators are widely used in many applications, such as medical lasers and plasma generators. The rise time is a crucial parameter for the generator. This paper focuses on the modeling and optimal design of Marx pulse generator based on silicon carbide (SiC) MOSFETs and magnetic drive. First, based on the model of toroidal transformer and the equivalent circuit model of SiC MOSFETs, the electromagnetic transient model of the Marx generator with the magnetic drive is established to analyze the influence of circuit parameters on the rise time. Then, the toroidal transformer with shell‐type coil structure is proposed, which has a lower leakage inductance. Furthermore, a leakage inductance model is established for the novel transformer structure, and the optimal design is carried out. Finally, the Marx generator test platform is built to validate the model and optimization method. The test results indicate that the pulse generator proposed in this paper has a pulse rise time of 20 ns under the condition of 2 kV/20 A, which represents a 33.3% increase in performance compared to the proposed Marx generator. © 2025 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.

A UV-C LED Lamp Driver Circuit Applied to a Direct-Current-Input Voltage Source for Sterilization and Germicidal Applications

UV-C LEDs, which offer short-wavelength characteristics and serve as an alternative to traditional UV mercury lamps, represent a new light source for applications in space decontamination and surface disinfection. This paper presents the design and development of a UV-C LED lamp driver circuit configured to operate with a DC-input voltage source for sterilization and germicidal purposes. The primary circuit integrates a modified buck converter with a flyback converter, resulting in an innovative single-stage, single-switch DC-DC power converter. Additionally, the proposed electronic driver recovers energy stored in the transformer’s leakage inductors, enhancing overall circuit efficiency. A prototype driver circuit with a 3.3 W power rating (10 V/330 mA) is developed for a UV-C LED lamp intended for sterilization and germicidal applications with a DC-input voltage source. The experimental results from the prototype circuit, tested at an 18 V DC input, confirm the functionality of the proposed electronic driver for UV-C LED sterilization and germicidal lighting. Additionally, the circuit achieves efficiency exceeding 91%.

A modelling technique to determine the high frequency transformer leakage inductance using the winding structure

The operation and efficiency of isolated DC-DC converters, critical components in solid-state transformers, are significantly impacted by leakage inductance in high-frequency transformers (HFTs). Different converters have varying demands regarding leakage inductance, ranging from precise control to minimal inductance. For instance, the performance of bidirectional isolated converters (BIDCs) and resonant converters is dependent on leakage inductance for the delivery of power. This study proposed a method for the control of leakage inductance by altering the winding configuration. The technique involved positioning the primary and secondary windings at predetermined heights to increase the separation between some winding turns, and thus, enhance leakage inductance. By not varying the average length of turns in the winding configuration, the proposed method was able to maintain a consistent copper loss. A modified mathematical model has been put forward to determine the leakage inductance effectively and precisely. The viability and accuracy of this method were validated through simulations and experiments using a three-phase HFT (3P-HFT) in a 3P-BIDC. The results showed that the leakage inductance that was calculated using the theoretical model was closely correlated to that of the simulation model, with only a variance of 3.9% and an error of 4.53% from the experimental results.

Selecting analytical method of leakage inductance calculation for optimizing high-voltage test transformer design

AN ACTUAL PROBLEM in transformer design is to optimize its design, since it allows you to create a competitive transformer. One of the objective functions in optimization algorithms for high-voltage test transformers is the ratio of the leakage inductive reactance of the transformer, reduced to the secondary side, to the load capacitance. Since the objective functions in the optimization procedure must be found many times, it is advisable to use approximate analytical calculation methods to calculate the leakage inductance. THE PURPOSE of the article is to analyze the error of the traditional analytical method for calculating the leakage inductance of power transformers with a rectangular axial cross-sections of the windings, and to develop a refined analytical method that takes into account the main design feature of high-voltage test transformers, which consists in the trapezoidal shape of the secondary winding cross-section. The refined method takes into account the change in the number of turns in the radial direction while maintaining the basic assumptions of the traditional method. METHODS. The error is studied by comparing the calculation results using these methods with the results of a numerical calculation of leakage inductance based on a 3D magnetostatic field, which are accepted as accurate. RESULTS. It is shown that the calculation error using the method proposed in the article is significantly reduced compared to the error of the method developed for power transformers with rectangular winding cross-sections. The ranges of changes in the relative geometric parameters of the base transformer have been determined, in which the error of this calculation method does not exceed 10%. The TGI 50/100 transformer, whose rated power is 5 kVA, was chosen as the base transformer. The developed analytical method is recommended for high-voltage test transformers optimization algorithms.

Analysis on Leakage Inductance and Winding Resistance of High Frequency Toroidal Transformer with Interleaved Winding and Litz Wire

Analysis on Leakage Inductance and Winding Resistance of High Frequency Toroidal Transformer with Interleaved Winding and Litz Wire

An Improved Model Predictive Current Control of BLDC Motor With a Novel Adaptive Extended Kalman Filter–Based Back EMF Estimator and a New Commutation Duration Approach for Electrical Vehicle

ABSTRACTAs a result of the increasing use of electric vehicles, ensuring high‐performance speed and torque control of brushless direct current (BLDC) motors has become of great importance for energy efficiency. In order to prevent the torque ripple of the finite control set model predictive current control (FCS‐MPCC), commutation moments are detected by Hall effect sensors in conventional methods. However, this method cannot exhibit a long‐life structure because of physical strain damaging the sensors and electrical connections. In this study, commutation moments and durations are captured and determined with a new approach. Commutation moments are captured with zero crossing detectors and commutation durations are determined by using the position information obtained from the encoder. Moreover, three‐phase back electromotive forces (EMFs) of the BLDC motor applied to FCS‐MPCC to predict the stator phase currents are estimated with a novel adaptive extended Kalman filter (AEKF) which has the estimation capability without any speed sensor. Furthermore, another improvement is implemented in the calculation of the cost function of FCS‐MPCC by taking into account the difference between the predicted and the reference torque of the BLDC motor different from the conventional MPCC methods. The proposed drive system is tested under different scenarios at various speeds under load torque, stator resistance, and leakage inductance variations in simulation. It is proven by simulation results that phase commutations can be achieved stably with the proposed phase commutation determination method. In addition, the simulation results show that the proposed novel AEKF estimator and the FCS‐MPCC in which the cost function is calculated by regarding not only the current error but also the moment error have impressive prediction and control performance, respectively.

A Novel Methodology for Detecting and Quantifying Transformer Winding Deformation Using Frequency Response Analysis

A transformer has windings and its structural integrity depends on several factors such as system short circuits,mechanical shocks during transporting,reduction of pressure of winding clamping etc.A transformer can experience severe electromagnetic forces on its winding structure during short circuits. These electromagnetic stresses can lead to winding deformation in both the radial and axial directions.Obviously it will lead to transformer failure. Historicallythe winding deformation and movement in transformer winding is detected by the measurement of leakage inductance. However immediate radial deformation results in a significant change in the leakage inductance. But axial deformation has less change in leakage inductance. Thus leakage inductance measurement method has less sensitivity.Another method was introduce in 1978 based on the frequency response analysis(FRA). In FRA testing method a signal is injected in to one terminal at the same time the response at the other terminal is measured. The commonly used methods for signal injection are swept frequency method(SFRA) and Impulse method(IFRA). This topic proposes a methodology for locating and quan tifying winding deformation in transformers.It is based on the fitting of a Gray Box transformer model to FRA measurements. Here the FRA measurements were recorded both before and after the fault. The refined variations in the key parameters of the model can be then used to quantify winding deformation with in power transformers. Key words: Frequency response analysis, Swept frequency response analysis (SFRA), Impulse response analysis (IFRA), Gray box transformer model. Winding deformation. Keywords: Frequency response analysis, Swept frequency response analysis (SFRA), Impulse response analysis (IFRA), Gray box transformer model. Winding deforma tion,Buckling

A New High Voltage Gain Common‐Ground Step‐Up DC‐DC Converter Integrating Coupled‐Inductors and Switched‐Capacitors

ABSTRACTThis study proposes a new high‐voltage gain quadratic‐structured common‐ground step‐up DC‐DC converter, integrating coupled‐inductors and switched‐capacitors. This configuration achieves a significant voltage gain without necessitating either a substantial duty cycle or an elevated turn ratio in the coupled‐inductors. A critical innovation is the embedding of the secondary windings of the coupled‐inductors into the switched‐capacitor cell, which not only enhances voltage gain but also effectively suppresses the inrush current typical in such cells. The converter's features include the successful recycling of energy from the leakage inductors; low voltage stress exerted on power switches; zero‐current switching (ZCS) turn‐on of the main switch; ZCS conditions for the diodes' turn‐off; reduced switching losses because of the application of a quasi‐resonant (QR) operation between the leakage inductors and middle capacitors; simultaneous operation of the power switches; continuous input current; a wide duty cycle range; and a common‐ground output–input connection. The operating principle, steady‐state analysis (CCM and DCM), design considerations, efficiency calculation, small‐signal modeling with controller design, and comparisons with other related converters are provided. Finally, experimental results from a 100‐ to 300‐W prototype with 20‐ to 30‐V input and 400‐V output are given to validate the proposed converter's theoretical analysis and feasibility.

Analysis and Design of Stacked Coupled Inductor Quadratic Boost Converter With a Lossless Snubber Cell

ABSTRACTThis paper introduces the stacked coupled inductor quadratic boost converter with an inductorless, passive lossless snubber cell suited for high step‐up applications with various microgrids. Some design constraints can be selected from the voltage gain techniques of the high step‐up converters to obtain the solution of improvement performance of converter. The proposed converter utilizes quadratic boost converter and coupled inductor to attain high voltage gain beyond the voltage multiplier/lift cells. In this proposed converter, the use of a stacked coupled inductor type introduces the leakage inductor to snubber cell as an inductor without using an extra inductor in proposed snubber cell. Thus, a regenerative snubber cell is used to achieve a high system efficiency. Compared with earlier counterparts, the solution of attaining a high voltage gain in the proposed converter and passive lossless snubber cell leads to an increase in the converter's performance, reliability, and robustness. The theoretical expectations are supported by simulations and verified by experimental results obtained by implementing a 300‐V, 120‐W prototype.

Assessment of Non-Linear Modeling of Ladle Furnace Transformer Using Finite Element Analysis

This paper assesses a non-linear model of a three-phase Ladle Furnace Transformer, on slow front transients under no-load conditions. The model is designed to maintain accuracy and reduce complexity in estimating equivalent circuit parameters using three methods: analytical calculations, finite element analysis, and test measurement. The results reveal that analytical and finite element methods show discrepancies lower than 1%. Tests measurement, on the other hand, shows discrepancies higher than 5%, when compared to ones obtained from analytical and finite elements methods. Such discrepancy is particularly high in the estimation of leakage inductances and capacitances, and it is attributed mainly to differences between the transformer design and its actual assembly. Additionally, there are inherent inaccuracies in test procedures and instrumentation errors. The proposed model does not require difficult-to-obtain parameters and incorporates the non-linearity of magnetizing inductance, contributing to more accurate simulations. This simplified model is suitable for analyzing slow front transients and can be integrated into future studies addressing vacuum circuit breaker switching in electric arc furnace power systems, contributing to performance improvements in industrial applications. Additionally, the methodology for parameter determination can be applied to conventional power transformers, highlighting its versatility.

Postfault Strategy for Dual Three-Phase PMSM With Reduced Current Loops Considering Leakage Inductance

Postfault Strategy for Dual Three-Phase PMSM With Reduced Current Loops Considering Leakage Inductance

Investigation of a fast gate driver based on a half-turn planar transformer.

This paper presents a magnetically isolated gate driver for the fast switching of IGBT (Insulated Gate Bipolar Transistor) in compact pulsed power sources with sharp rising edges and flat-top pulses for the application of electromagnetic launch and food processing. The proposed gate driver is implemented based on a planar transformer with a half-turn winding arrangement to increase the amplitude of the driving voltage pulse. With the half-turn winding arrangement, the leakage inductance of transformers decreases by 31.1% compared to the interleaving structure. This decrease enables a fast rise time of the driving voltage pulse. Furthermore, the gate drivers are used to drive the IGBT switching a Blumlein pulse forming network. The results show that the di/dt of the applied commercially available Si IGBT is about 10.10 A/ns with a gate voltage of 50V and a gate capacitance charging time of about 88ns, proving the effectiveness of the gate driver and providing a high-performance driving scheme for the fast switching of Si IGBT.

A single switch high step-up DC-DC converter derived from coupled inductor and switched capacitor for a photovoltaic system

This study suggests a single switch high step-up DC-DC Converter derived from coupled inductor and switched capacitor used in Grid-Connected Photovoltaic systems. In the suggested converter, a part of the yield voltage is produced by parallel charging of the capacitors on the side of the secondary winding and their series discharge together with the secondary winding. The other part of the output voltage is obtained by simultaneously charging the boost and buck-boost capacitors and discharging them in series with the input voltage source. Finally, these two parts make the output voltage in series, so that high voltage gain with proper duty cycle is obtained. In addition, boost and buck-boost capacitors absorb leakage inductance energy leading to a reduction of the switch voltage stress. As a result, switching losses are reduced and by choosing a switch with lower RDS(ON), conduction losses are also reduced. Finally, a prototype with an output power of 200 Watts, and a voltage conversion of 24–400 Volts was made to confirm the performance in the laboratory, which has the highest efficiency of 95.89%.

Hierarchical equalization scheme for retired lithium-ion battery packs based on inductor-flyback transformer

Some lithium-ion batteries can be reused after sorting and recombination. Equalization of these batteries during the process of step utilization is an effective way to improve the inconsistency of battery packs and extend their lifespan. This paper proposes a hierarchical equalization topology based on a combination of inductor and transformer, which is divided into intra-group and inter-group battery equalization. The intra-group equalization circuit achieves energy transfer between non-adjacent individual batteries through an improved Buck-Boost circuit. The inter-group equilibrium circuit exchanges energy between any battery subpackages and the entire battery pack using a flyback transformer. An LCD (Inductance-Capacitor-Diode) lossless absorption network is added to the transformer to absorb voltage spikes caused by leakage inductance while achieving soft switch to reduce switch losses. Considering that retired lithium-ion batteries can affect battery capacity and State of Charge (SOC) estimation accuracy due to aging issues, a modified Extended Kalman Filter (EKF) algorithm is proposed to improve battery SOC estimation accuracy. A fuzzy logic controller is introduced into the SOC-based control strategy to improve the equalization efficiency of the battery pack. Finally, to validate the effectiveness of the proposed equalization scheme, a model is built and simulated using MATLAB/Simulink software. The experimental results show that compared with the traditional double-layer inductor equalization scheme using the most value equalization algorithm and fuzzy logic control algorithm respectively, this equalization scheme has a faster equalization speed and higher equalization efficiency.

Energy regulation of impulse current generator modulated DC arc discharge

AbstractThis paper proposes a method of impulse current generator modulated DC arc by combining the advantages of pulse and the RF to solve the low electron energy problem of direct current arc. Through experimental analyzing the electrical, spectral, and optical characteristics of the arc, the effect of impulse current generator (ICG) on improving electron energy is discussed. The results show that the ICG consumes more energy to enhance the strength of arc discharge, and therefore electron energy is increased in a microsecond scale. In addition, it is found that the electron energy of the arc discharge can be adjusted by varying inductance, capacitance, and discharge tube: increasing the inductance or capacitance can increase the electron energy firstly and then decrease it. In adjusting the three adjustable components, adjusting the inductor is the most effective method, followed by adjusting the capacitor, and adjusting the repetition frequency has the least effect. The reason is discussed, and it is believed that the results are related to leakage inductance and distributed capacitance.

A novel high step‐up, low switching voltage stress DC‐DC converter using leakage inductance for resonant boosting

AbstractA DC‐DC converter with high boost and low switching voltage stress is proposed by combining switched capacitor (SC) and coupled inductor (CL) techniques based on a conventional boost circuit. The design methodology of this converter includes substituting SC for a single switch in the boost converter, combining CL, and integrating a resonant boost circuit for absorbing leakage inductance. The improved power switch topology in this design has lower voltage stress, lower diode current stress, fewer total components, and common ground than other conventional DC‐DC converters. The operating modes and steady state analysis of the converter are provided in terms of leakage inductance utilization, with component stress derivation and theoretical efficiency analysis. In addition, comparisons with other dc‐dc converters are made. Subsequently, experiments were conducted on a 200 W DC‐DC converter prototype to verify the reliability of the converter.

Modeling, design, and performance analysis of a Y‐source DC‐DC converter under limitations of hardware and leakage inductances

Modeling, design, and performance analysis of a Y‐source DC‐DC converter under limitations of hardware and leakage inductances

Design procedures for series–series wpt systems: A comparative analysis

The Series–Series (SS) compensation is one of the most commonly employed topologies for enhancing the efficiency of Wireless Power Transfer (WPT) systems. In this topology, two capacitors are connected in series with the transmitter and receiver coils. Currently, in the literature, these capacitors are tuned to resonate with the self-inductance of the coils at the nominal frequency. Anyway, analyzing the circuit, another interesting possibility emerges: the calibration of the capacitors to resonate with the leakage inductances of the coupled coils. This approach, currently not investigated in the literature, leads to a system with significantly different characteristics. A comparative analysis between these two methods is lacking in the literature. Therefore, this paper aims to fill this gap by proposing an in-depth comparison between the two design procedures, with the aim of providing useful insights to designers in selecting the most appropriate design technique for their application. The analysis includes both steady-state and transient conditions. In particular, the input impedance, voltage transfer function and the transmission efficiency at different frequencies and coupling coefficients are compared. The theoretical results are validated experimentally. The results obtained are extremely interesting and are particularly useful for selecting the most appropriate sizing technique for a given application during the design phase.

Design of a new modular‐isolated‐forward‐based active snubber cell for power switches

AbstractIn this paper, a new modular‐isolated‐forward‐based active snubber cell (SC) for power switches is designed. In the proposed new SC, the zero voltage transition (ZVT) technique is implemented with a forward converter although the current counterparts generally use a flyback converter. In the converter with the new SC, the main switch is turned on with ZVT (full zero voltage switching [ZVS]) and turned off with ZVS, the main diode is turned off with zero current switching (ZCS), the auxiliary switch is turned on with ZCS and turned off with ZVS, and the parasitic capacitor energies are recovered. In addition, thanks to the forward converter, it has been possible to minimize the transformer leakage inductance and greatly reduce the current values of devices in the new SC. The new cell is applied to a single‐phase, grid‐connected, T‐type three‐level inverter (T2‐3LI) as an example. A detailed steady‐state analysis of this inverter was made, and the theoretical analysis was confirmed with measurement results taken from a prototype with 100 kHz and 3.3 kW values. Compared to its hard switching (HS) equivalent, in the converter with soft switching (SS) cell, the total circuit loss was reduced from about 248 W to 86 W, thus achieving an increase in the total efficiency from 92.5% to 97.4%.

Ripple current control for single phase-shift dual active bridge converters

Nowadays, the need for isolated bidirectional DC/DC converters is growing. In these types of equipment, the dual active bridge topology is widespread, where mostly the trans- former leakage inductance value determines its dynamic behavior. Voltage imbalance between the primary and secondary side results in unwanted excessive transformer peak current if the leakage in- ductance is low, thus limiting the load transient response of the converter. In this paper, a ripple current control method is pre- sented, which reduces the transformer peak current to its minimal level, furthermore, allows the magnetizing current components to be distributed between the primary and secondary sides in an ar- bitrary proportion. The proposed control was tested in HIL sim- ulation and on a real 360kW dual active bridge converter. Based on the results the current stress on semiconductors and DC capac- itors were reduced while the utilization and the efficiency of the converter were increased.