Saturable Inductor Research Articles

Paralleled Variable Inductor Phase-Shifted Full-Bridge Converter With Full-Load Range ZVS and Low Duty Cycle Loss

This paper presents a new phase-shifted full-bridge topology using a new variable inductor. In this topology, a variable inductor is connected in parallel with a near-ideal transformer. The ZVS of the switches is achieved over the full load range using the parallel current provided by the variable inductor. And the adjustable parallel current reduces conduction losses. Under the orthogonal DC magnetic potential, the variable inductor has similar characteristics to the saturated inductor, which is beneficial to reduce the conduction loss caused by the parallel current. Since the topology has no series inductor and the leakage inductor is extremely small, the proposed converter has the advantages of extremely small duty cycle loss, larger transformer turns ratio, smaller primary current stress, smaller secondary voltage stress, and smaller output current ripple, which are beneficial to improve the efficiency and frequency of the converter. An experimental platform was established. Theoretical analysis and experimental verification were carried out.

A novel cost-effective power supply model for industrial appliances based on triangular magnetic shunt transformer design

This paper presents a new design of a magnetic shunt transformer for use in industrial microwave generators. The proposed transformer has a triangular shape and offers several advantages over existing transformer designs, including reduced volume and maintenance costs. We provide a detailed analysis of the transformer's dimensions and an equivalent model of the three-phase high voltage power supply system. The results of this study have significant implications for the field of industrial microwave generator design and could lead to the development of more efficient and costeffective systems. The resulting model is comprised of saturable inductors capable of accounting for the non-linear phenomena of saturation. The power supply is simulated using MATLAB/Simulink with a neuro-fuzzy ANFIS approach. The results are compared to experimental validations of a single-phase reference power supply for a magnetron, validating the proposed power supply. Additionally, the simulation results demonstrate the effectiveness of the proposed design, which outperforms existing transformers in terms of volume, energy efficiency and maintenance costs.

The Development of a Compact Pulsed Power Supply with Semiconductor Series Connection

In this study, high-voltage switching was performed by connecting semiconductors in series. By employing Snubber circuits and voltage divider resistors for each semiconductor, the destruction of the semiconductors was prevented. Additionally, a pulse transformer was installed between the function generator and the photocoupler to isolate the gate circuit, preventing electrical discharges in the circuit and enabling operation at an output voltage of 10 kV and an operating frequency of 200 Hz. The temperature of the semiconductors increased with the increase in operating frequency, which was counteracted by connecting charging resistors and capacitors to limit the current to the semiconductors. As a result, operation at 430 Hz became possible. Furthermore, a saturable inductor (SI) was connected to enable continuous operation. The SI delays the rise of the current and creates a phase difference, thereby reducing the power consumption of the conductor and mitigating the temperature rise, enabling continuous operation at 300 Hz. Moreover, by increasing the number of semiconductor series stages to six, an output voltage of 20 kV was confirmed in tests. By using two semiconductor series circuits, the pulsed power supply that can be changed to any pulse width was also created. As a result, output voltages with arbitrary pulse widths from 5 μs to 30 μs were confirmed.

Use of a Partially Saturating Inductor in a Boost Converter with Model Predictive Control

Increasing the power density in switched mode power supplies is one of the main goals in power electronics. This aim can be achieved by using smaller inductors operating at partial magnetic saturation. In this work, a partially saturating ferrite core inductor is exploited in a switching DC-DC boost converter, regulated through nonlinear model predictive control. A nonlinear behavioral inductor model, identified through experimental measurements, accounts for both magnetic saturation and losses. The simulation results show that the converter output voltage is correctly regulated and the imposed current constraints are fulfilled, even when partial magnetic saturation occurs. Comparisons with traditional control techniques are also presented.

A Position-Insensitive Nonlinear Inductive Power Transfer System Employing Saturable Inductor

Most of the practical inductive power transfer (IPT) systems are the ones with variable coupling coefficients and loads. The output voltage, current and power are affected by the variation in coupling coefficient and load. In this paper, a novel approach based on a nonlinear resonator is proposed to obtain stable output voltage, which is independent of coupling coefficient and load variation. First, the theory and properties of nonlinear resonators are analyzed by Duffing equation. Then, a nonlinear IPT system with a magnetic saturation inductor is proposed, and the saturable inductor modeling and its effect on system performance are further studied. Finally, the experimental prototype is built to validate the effectiveness of the nonlinear IPT system. The experimental results show that when the coupling coefficient varies from 0.32 to 0.24 and the load resistance varies from 80Ω to 120Ω, the system works in a nonlinear state, the output voltage ripple is 1.77%, and the overall efficiency of the system is not less than 82.60%. The experimental results are basically consistent with the theoretical analysis. The novel design approach improves the output voltage stability with respect to position misalignment and load variation, and the bandwidth of the system is also enhanced.

Auxiliary Resonant Snubber‐Based Soft‐Switching Converter with Saturable Inductor to Reduce Reverse Recovery Current and Loss

The auxiliary resonant snubber‐based converter (ARSC) has the advantages of low dead‐time effect and low switching loss. However, the auxiliary switches suffer from high reverse recovery loss and high reverse recovery current in high‐switching frequency application. Thus, the ARSC with saturable inductor is proposed to solve the problem above. In this paper, the operating principle of ARSC with saturable inductor is analyzed, and the duty cycle operating range that can realize ZVS in the full load range is deduced. The reverse recovery model of the auxiliary switching device body diode is established to analyze the circuit parameters' influence. Then, the influence of the saturable inductor on the reverse recovery peak current and reverse recovery loss is analyzed. Based on the analysis results, the saturable inductance parameters are designed. Finally, based on the experimental platform of the ARSC, the effectiveness of the proposed method is verified. © 2023 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

ZVS Realization of H-Bridge Low-Voltage High-Current Converter via Phase-Shift and Saturable Control

A zero-voltage switching (ZVS) H-bridge phase-shifted low-voltage high-current converter with saturable inductors is proposed in this paper. The introduction of saturable inductors solves the short circuit problem caused by high-frequency on–off of the power tube, and effectively inhibits high-frequency voltage oscillation and voltage spikes of the rectifier tube. In addition, when the current flowing through the saturable inductor does not change rapidly, it exhibits a low impedance and consumes very little power. The detailed design process of main parameters in the converter is presented to provide design reference for power supply workers. To verify the effectiveness of design, a 3 kW(15 V/200 A) prototype converter is built. This low-voltage high-current prototype has around 90% efficiency, and can suppress high-frequency voltage oscillation and voltage spikes, avoiding the short circuit problem of power tube, all of which are verified by experimentation.

Design and modelling of a controlled saturable inductor for an LCC-S compensated WPT system

This paper analyses the design of a controlled variable inductor adopted as the series inductance of an LCC-S compensation network in an Inductive Wireless Power Transfer system. In this compensation topology, the power transfer to the load can be controlled by varying the differential inductance of the component through a DC bias. The analytical design process of a double E ferrite core variable inductor is presented, and the specifications for an experimental prototype are proposed. The design output is verified with FEM simulations to validate the obtained differential inductance profile and with circuit simulations to test the non-linear behaviour of the component under the typical current and voltage waveforms of the LCC-S compensated Wireless Power Transfer system. Finally, a prototype is realized, characterized and tested in an experimental Wireless Power Transfer system.

Performance of a Multigap Multiaperture Pseudospark Switch in Series With the Saturable Inductor

In this study, experimental investigation has been performed for discharge characteristics of a multigap multiaperture (MGMA) configuration of pseudospark switch (PSS) with a saturable inductor (SI) in series at the anode. The impact of the number of inductor cores on the commutation process is studied experimentally. Initially, in the commutation process, when the anode voltage is 40 kV with five toroid cores, the inductor is unsaturated, and it offers high impedance, resulting in a slow current rise rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx 2.5$ </tex-math></inline-formula> kA/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> with fast voltage drop rate. During the second phase, when the inductor gets saturated and offers low impedance, it leads to a fast-current rise rate of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\approx 4.35$ </tex-math></inline-formula> kA/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{s}$ </tex-math></inline-formula> . Due to the SI, the discharge current rise lags behind the breakdown voltage drop of MGMA-PSS. It results in a significant reduction in power dissipation across the switch during the commutation process. Furthermore, equivalent electrical circuit modeling has also been proposed for the estimation of power losses during the commutation process. During the application of 40-kV anode voltage with five inductor cores at 30-Pa background H2 gas pressure, the commutation losses have been reduced up to ≈95%, which also enhanced the performance of PSS. The proposed analysis and optimization of the inductor core would be very much useful for the reduction in the anode erosion and improved the switching performance of the MGMA-PSS.

Inductor Saturation Compensation in Three-Phase Three-Wire Voltage-Source Converters Via Inverse System Dynamics

In three-phase three-wire (3P3W) voltage-source converter (VSC) systems, utilization of filter inductors with deep saturation characteristics is often advantageous due to the improved size, cost, and efficiency. However, with the use of conventional synchronous frame current control methods, the inductor saturation results in significant dynamic performance loss and poor steady-state current waveform quality. This article proposes an inverse dynamic model-based compensation (IDMBC) method to overcome these performance issues. For this purpose, two-phase exact modeling of the 3P3W VSC control system is obtained. Based on the modeling, the inverse system dynamic model of the nonlinear system is obtained and employed such that the nonlinear plant is converted to a virtual linear inductor system for linear current regulators to perform satisfactorily. Further, to control phase currents in the synchronous frame, a two-phase coordinate transformation is proposed. The IDMBC method is tested via dynamic command response and waveform quality simulations and experiments that employ saturable inductors reaching down from full inductance at zero current to 1/9th inductance at full current. The results obtained demonstrate the suitability of the method for 3P3W VSCs employing saturable inductors.

Identification of DC Thermal Steady-State Differential Inductance of Ferrite Power Inductors

In this paper, we propose a method for the identification of the differential inductance of saturable ferrite inductors adopted in DC–DC converters, considering the influence of the operating temperature. The inductor temperature rise is caused mainly by its losses, neglecting the heating contribution by the other components forming the converter layout. When the ohmic losses caused by the average current represent the principal portion of the inductor power losses, the steady-state temperature of the component can be related to the average current value. Under this assumption, usual for saturable inductors in DC–DC converters, the presented experimental setup and characterization method allow identifying a DC thermal steady-state differential inductance profile of a ferrite inductor. The curve is obtained from experimental measurements of the inductor voltage and current waveforms, at different average current values, that lead the component to operate from the linear region of the magnetization curve up to the saturation. The obtained inductance profile can be adopted to simulate the current waveform of a saturable inductor in a DC–DC converter, providing accurate results under a wide range of switching frequency, input voltage, duty cycle, and output current values.

An Overview of Saturable Inductors: Applications to Power Supplies

This article presents an overview of saturable inductors that are intentionally saturated by the load current and their applications to power supplies. After introducing the fundamentals of magnetization and nonlinear inductance, three types of saturable inductors are differentiated. They are based on the way nonlinearity of the core material is used. The partial saturation, the saturation of swinging inductors and the full saturation. Subsequently, this article focuses on the application to power supplies: it identifies the main reasons for using saturable inductors, like improving the efficiency or reducing the size of the magnetic component by using stepped air-gaps or partial saturation and gives an overview on this topic and its main publications. Afterwards some concepts and circuits taking advantage of saturable inductors are presented in more detail, especially improving the light load efficiency of a point of load buck converter, ensuring zero voltage switching over a wide load range in a phase-shifted full bridge circuit, a nonlinear commutation circuit, and a passive and active power factor correction.

A study of ferroresonance in underground distribution network for 15MVA, 33/11 kV injection substation

This provides an overview of ferroresonance phenomena, modeling aspects and practical experience in recognizing and mitigating the effect of ferroresonance in the power network. In particular, we will present symptoms of ferroresonance. In this study, ferroresonance phenomenon are investigated under the modelling of the underground cable of 15 MVA, 33/11/0.415 kV with four feeders supply over 31 distribution transformers of Garki 1 service unit, Abuja, conducted using MATLAB/SIMSCAPE software package. The network is subjected to switching resulting in the formation of a series LC combination prone to ferroresonance. The waveforms and total harmonic distortion charts obtained are observed, analyzed and then used to design Harmonic filters which have been implemented to mitigate ferroresonance in the network. The simulated ferroresonance phenomenon was suppressed using Shunt Active Harmonic Filter connected in parallel to the network. A reduced harmonic content and dampened event when compared to a non-filtered event was observed. Application of Shunt Active Harmonic filter reduces ferroresonance effect by 67.743%.&#x0D; Keywords: Ferroresonance, Transformer, MATLAB/Simscape, Harmonic Distortion, Power system Modelling, Saturable inductor, Capacitance

Development of a High-Frequency Burst Pulse Generator for Cancer Cell Treatment and Comparison Between a High-Power Burst Pulse and a Single Pulse

Cancer treatment based on ultrashort pulses of strong electric fields has been developed as a novel biological application. This article focuses on the design of a compact high-power nanosecond pulsed electromagnetic wave generator for realizing cancer treatment via ultrashort pulsed electric fields. For this purpose, we developed a pulsed power generator that continuously outputs multiple pulses via a nonlinear transmission line (NLTL) using magnetic switches. The NLTL comprises a ladder of capacitors and saturable inductors and generates a pulse train by delaying the propagation of each pulse using the magnetic switch of each ladder. In this article, we achieved a higher output frequency compared to the previous generator. The frequency was increased from 13 to 150 MHz by employing a coaxial structure instead of discrete components. In addition, we demonstrate that the application of burst pulses to cancer cells is more effective than single pulses under the same conditions.

Impact of Inductors Saturation on Peak-Current Mode Control Operation

This article analyzes and discusses peak-current mode control (PCMC) in dc-dc voltage regulators using power inductors subjected to saturation. It is proved that the impact of inductors saturation on the operation of the PCMC regulators can be reliably predicted by means of the proposed mathematical model and technique. The results of circuit simulations and experimental measurements, regarding a dc-dc boost regulator, validate the theoretical analysis and the proposed model. The results confirm that the use of saturable inductors is a viable and reliable solution for PCMC regulators and demystify some concerns about the behavior of saturable inductors in the presence of line/load transients and overloads.

Dynamic Wireless Charging: Reflexive Field Containment Using Saturable Inductors

In dynamic wireless charging applications, segmented transmitter coils transfer power to a moving receiver coil. This article proposes a method in which the field strength in coupled transmitter coils automatically adjusts based on the position of the receiver. Specifically, a saturable inductor is applied to provide a high uncompensated inductive reactance in the uncoupled condition. By exploiting the reflected reactance as the system approaches the maximum coupled condition, the inductor saturates and the field strength in the coupled transmitter coils automatically increases. The field strength is at its peak when the transmitting and receiving coils reach their maximum coupling and sharply decreases when the receiver is decoupled from the transmitter. Consequently, the difference between the coupled and uncoupled currents in the transmitter coil is maximized, resulting in a near six-fold improvement in field containment performance compared to previously reported findings. This allows for system-level efficient power transfer and compliance with electromagnetic emission standards without complex shielding circuits and auxiliary active position detection approaches. We present the analysis, design criteria of the compensation network, and experimental validation for the proposed method.

Current Control of Single-Phase VSC Systems With Inductor Saturation Using Inverse Dynamic Model-Based Compensation

In voltage-source converter (VSC) systems, utilization of filter inductors with deep saturation characteristics is often advantageous due to the improved size, cost, and efficiency. However, with the use of conventional current regulation (CCR) methods, the inductor saturation results in significant dynamic performance loss and poor steady-state current waveform quality. This paper proposes the inverse dynamic model (IDM)-based compensation method to overcome these performance issues. The method converts the nonlinear inductor of the plant to a fictitious linear inductor such that linear current regulators can perform satisfactorily. In conjunction, identification of L–R parameters is performed to obtain IDM of the system within an acceptable range of sensitivity yielding satisfactory performance. The performance issues of CCR methods with saturable inductor are demonstrated by simulations and experiments. Then, the proposed method is experimentally verified on a single-phase 1.5-kW grid-connected VSC. The performance improvement over the CCR methods is verified by a detailed comparison of experimental waveforms.

Parameters of Passive Ferroresonance Suppression Circuit (FSC) Affecting Ferroresonance Damping and Normal Operating Voltage and Current of Capacitive Voltage Transformer (CVT)

This paper discusses the effect of parameters of passive Ferroresonance Suppression Circuit (FSC) on Capacitive Voltage Transformer (CVT) in not only the mitigation of ferroresonance oscillation, but also the normal operating voltage and current of CVT. The passive FSC composed of a resistor paralleled with a saturable reactor that has been a series circuit of a resistor and a saturable inductor. In this study, the resistance values have been varied. Then, one of the resistance variations has been used to damp the ferroresonance oscillation during the simulation with load variation of CVT. The opening and the reclosing of the circuit breaker have been utilized to initiate the ferroresonance on CVT. The results have showed that the existence of passive FSC with the given parameter values could effectively suppress the highly distorted overvoltage and overcurrent of ferroresonance oscillation, but the normal operating voltage and current of CVT have been increased during FSC resistor variation and have been decreased during saturable reactor resistor variation. The resistance value of FSC has been linear with the peak voltage and the ripple of waveform, whereas the resistance value of saturable reactor has been opposite with the peak voltage and the ripple of waveform. Furthermore, the load variation of CVT affected the ferroresonance behaviour and the peak voltage and current of CVT. Regarding those results, the electrical engineer should be able to choose the design of FSC appropriately in order to not only get the effective ferroresonance mitigation, but also to maintain the normal operating conditions of CVT in the future.

Discharge Characteristics of a Pseudospark Switch in Series With a Saturable Inductor

High power pseudospark switches (PSSs) can control pulsed high voltage, high peak current discharges. In this paper, a PSS in series with a saturable inductor at the anode is investigated. The commutation process is analyzed with a time-resolved method. And the effects of the number of magnetic cores and anode voltages on discharge characteristics are studied experimentally. At the beginning of commutation process, when the anode voltage is 10.4 kV with four magnetic cores, the inductor is unsaturated, and there is a flat plateau of the forward voltage drop after the anode voltage drops rapidly to about 200 V, at the same time the current rise rate is 2.8 kA/ $\mu \text{s}$ . When the inductor is saturated, there is a voltage spike that occurs at the end of the flat plateau, and the current simultaneously rises rapidly at the rate of 6.4 kA/ $\mu \text{s}$ . The current sharp rise lags behind the voltage drop of the pseudospark gap, and the electrode erosion and energy dissipation reduce significantly. When the anode voltage is 15.6 kV, the commutation losses reduce by about 30% with seven cores in series at the anode. As a result, it is evident that the discharge process will speed up if the anode voltage is higher. And the trigger delay decreases by up to 8% when the anode voltage varies from 5.2 to 15.6 kV. Finally, in order to obtain a reproducible pseudospark discharge by the use of a saturable inductor, the number of magnetic cores has to be optimized for different anode voltages.

Influence of Parasitic Parameters on DC–DC Converters and Their Method of Suppression in High Frequency Link 35 kV PV Systems

Photovoltaic (PV) power generation has shown a trend towards large-scale medium- or high-voltage integration in recent years. The development of high-frequency link PV systems is necessary for the further improvement of system efficiency and the reduction of system cost. In the system, high-frequency high-step-up ratio LLC converters are one of the most important parts. However, the parasitic parameters of devices lead to a loss of zero-voltage switching (ZVS) in the LLC converter, greatly reducing the efficiency of the system, especially in such a high-frequency application. In this paper, a high-frequency link 35 kV PV system is presented. To suppress the influences of parasitic parameters in the LLC converter in the 35 kV PV system, the influence of parasitic parameters on ZVS is analyzed and expounded. Then, a suppression method is proposed to promote the realization of ZVS. This method adds a saturable inductor on the secondary side to achieve ZVS. The saturable inductor can effectively prevent the parasitic elements of the secondary side from participating in the resonance of the primary side. The experimental results show that this method achieves a higher efficiency than the traditional method by reducing the magnetic inductance.