Resonant Inductor Research Articles

Design of a Bidirectional CL3C Full-Bridge Resonant Converter for Battery Energy Storage Systems

In this study, a bidirectional CL3C full-bridge resonant converter was developed using a bidirectional active bridge converter as the main framework to improve conventional LLC resonant converters. A resonant inductor and resonant capacitor were installed at the secondary side of the developed resonant converter. The bidirectional operation of this converter enables zero-voltage switching at the supply-side power switch and zero-current switching at the load side. The aforementioned phenomena enhance the overall circuit efficiency and enable the resonant tank voltage to be increased in the reverse mode, which cannot be achieved with conventional bidirectional LLC resonant converters. The electrical equipment isolation function provided by a transformer made electricity usage safer, and digital control technology was adopted to control electrical energy conversion and simulate bidirectional energy conversion. Specifically, the experiment and simulation emulated how the developed converter enables energy transmission from a DC grid to a battery energy storage system through constant current–constant voltage charging and energy transmission from a battery energy storage system to a DC grid through constant power discharging.

Analysis and Comparison of Series Resonant Converter With Embedded Filters for High Power Density DCX of Solid-State Transformer

A series resonant converter (SRC) operating as a DC transformer (DCX) is a candidate for the isolated bidirectional DC/DC converters of solid-state transformers (SSTs). However, the input/output current ripple of the SRC is relatively high, which requires bulky parallel capacitors and low-pass filters such as C/LC filters. These additional components reduce the power density. In addition, to operate an SRC as a DCX, a small resonant inductance is desired to reduce the voltage gain variation and achieve a faster transient response. To resolve these problems, a SRC with embedded filters is studied. Adding a clamping capacitor between split transformers not only significantly reduces current ripples and the harmonic components of the input/output currents but also connects resonant inductors in parallel to reduce the equivalent resonant inductance. In addition, dividing the resonant current into two split windings reduces the RMS current of the transformer. This paper presents a detailed analysis, a design methodology, and a comprehensive comparison with the conventional half-bridge CLLC converter with C/LC filters. 1-kW prototypes with a 600-V input voltage and 200-V output voltage demonstrate the superiority of the proposed converter; the second harmonic of the output current was significantly suppressed by 19.3 dB compared with that of the conventional converter with the same power density. The loss breakdown showed the proposed converter mitigated copper loss by 9.47% and eliminated the losses of the filter and DC-link capacitors. The prototype of the proposed converter had the highest efficiency of 95.4% at full-load among prototypes.

Single-Switch Resonant Soft-Switching Ultra-High Gain DC-DC Converter With Continuous Input Current

An ultra-high gain DC-DC converter with single-switch structure is introduced in this paper. Full soft-witching is provided by simultaneous use of quasi-resonant performance of one resonant tank and leakage inductance of a three-winding coupled inductor (CI). Adopting the secondary and tertiary windings of the CI in separated voltage multiplier cells enables the converter to provide ultra-high voltage gain. The reverse recovery problem is resolved thanks to the quasi zero current switching performance of nearly all diodes, especially output diode because of the second resonant tank, so the total electromagnetic interference is significantly reduced. Continuous input current with low ripple expands the application of the proposed converter, especially in renewable energy applications. Steady-state performance and design considerations of the introduced converter are analyzed thoroughly and compared with recently introduced converters to establish its merits. Experimental results of a 200 W prototype are given to validate its analysis and performance.

External Magnetic Field Minimization for the Integrated Magnetics in Series Resonant Converter

The resonant dc–dc converter is preferred for high-efficiency applications due to its less switching loss and better electromagnetic interference (EMI) characteristics. However, in a wide range of steady-state voltage gain applications, such as the on-board charger application, the wide output voltage range will lead to a bulky resonant inductor, which will decrease the power density. Magnetic integration of the inductor and transformer is an effective way to reduce the total magnetic volume. However, the traditional integrated magnetics of transformer and inductor will result in high magnetic field intensity in the external space nearby the integrated magnetic component. This external magnetic field will cause large eddy current losses in the neighboring metal heatsink and serious EMI issues. In order to deal with this problem, an integrated winding structure with a negligible external magnetic field is proposed in this article. By rebuilding the external winding segments with a better coupling coefficient, the external magnetic field intensity is canceled without efficiency and size sacrifices. Detailed analysis and design procedures of the proposed structure are presented. A 6.6-kW dc–dc prototype is built to verify the cancelation effect of the magnetic field intensity in the neighboring external space.

Synchronous Rectification Based on Resonant Inductor Voltage for CLLC Bidirectional Converter

Synchronous rectification (SR) is an effective method to reduce the secondary side conduction loss of CLLC bidirectional resonant converter and improve its efficiency, but the SR driving signal in CLLC converter is hard to determine. Existing SR signal generating methods can be divided into three categories: theoretical calculation, voltage detection, and current detection. Compared with the other two methods, the current detection method has wider applicability and is insensitive to parasitic parameters, but usually requires lossy, bulky and costly current sensors, increasing the cost and size of the converter. This article proposed a SR scheme based on resonant inductor voltage. The polarity of the resonant current is obtained indirectly through the inductor voltage, thereby avoiding the use of current sensors. To handle the false pulses problem caused by parasitic oscillation, a corresponding SR control strategy is proposed. The SR driving signal is then adjusted according to the delay and transient requirements. Experimental results on a 380V/270V 3kW CLLC converter prototype were presented to verify the effectiveness of the proposed SR method.

Modelling and Implementing a Resonant Inductive Coupling Circuit Using Python and Cost-Effective Components for Wireless Power Transfer

Modelling and Implementing a Resonant Inductive Coupling Circuit Using Python and Cost-Effective Components for Wireless Power Transfer

High-Performance Power Converter for Charging Electric Vehicles

This paper presents the analysis, modeling, simulation and practical studies of resonant inverters with a voltage limitation on the resonant capacitor. The power circuits obtained in this way are characterized by the fact that the power consumption does not depend on the load changes, but is a function of the operating frequency, the value of the resonant capacitor and the supply voltage—these are the so-called inverters with energy dosing. Analytical dependences, simulations and experimental results were determined, which described the behavior of the studied power electronic devices. The obtained expressions for the inverter current in the different stages of the converter operation were the basis for the creation of the engineering methodology for their design and prototyping. Based on the derived basic ratios and characteristics, the capabilities of these devices for self-adaptation to the needs and changes of the load were demonstrated. A comparison of the characteristics of classical resonant inverters and those with energy dosing was made, thus demonstrating their qualities and advantages. The presented results display the properties of this class of circuits and the challenges to their effective application to find the optimal solution for the implementation of charging stations for different specific needs. On the other hand, the limitations in the use of these circuits were that no power was consumed from the power supply during the whole period, the lack of limitation of the maximum current through the transistors and the need for sufficient time to dissipate energy in the resonant inductor when working with high-resistance and low-power loads.

Efficient Authentication Protocol and Its Application in Resonant Inductive Coupling Wireless Power Transfer Systems

Chaos theory and its extension into cryptography has generated significant applications in industrial mixing, pulse width modulation and in electric compaction. Likewise, it has merited applications in authentication mechanisms for wireless power transfer systems. Wireless power transfer (WPT) via resonant inductive coupling mechanism enables the charging of electronic devices devoid of cords and wires. In practice, the key to certified charging requires the use of an authentication protocol between a transmitter (charger) and receiver (smartphone/some device). Via the protocol, a safe level and appropriate charging power can be harvested from a charger. Devoid of an efficient authentication protocol, a malicious charger may fry the circuit board of a receiver or cause a permanent damage to the device. In this regard, we first propose a chaos-based key exchange authentication protocol and analyze its robustness in terms of security and computational performance. Secondly, we theoretically demonstrate how the protocol can be applied to WPT systems for the purposes of charger to receiver authentication. Finally, we present insightful research problems that are relevant for future research in this paradigm.

Optimal Design of Fully Integrated Magnetic Structure for Wireless Charging of Electric Vehicles

Optimal design of a fully integrated magnetic structure for electric vehicle (EV) wireless charging is proposed in this article. The proposed approach helps save ferrite material, reduce the implementation cost, shrink the size of the converter, and improve the cost and power density. Typically, in a wireless charging system, an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC</i> resonant network and the receiver dc–dc converter are used, which require a bulky inductor in their structures. The integration of resonant inductor with the transmitter-side coil has been studied in the literature to reduce the overall cost and improve the power density of an EV wireless charger. The integration of the dc–dc inductor with the vehicle-side receiver coil is also introduced in the literature. However, the full integration of both resonant inductor and dc–dc inductor into the transmitter and receiver coils of the wireless charging system creates new design challenges that have not been addressed before. In this article, the proposed fully integrated magnetic structure and its design challenges are studied in detail. A procedure for achieving the optimal design of the fully integrated structure is presented. An optimization problem is defined to design the best magnetic structure and select the best values for the resonant elements and dc–dc inductor. The outcome of this integration is an all-integrated magnetic structure, compact converter, and efficient wireless charger. A 2.2-kW/85-kHz system is built to verify the feasibility of the proposed integrated wireless charging system, and its performance is evaluated through the experiment.

Fixed-Frequency Current-Fed LCL Series Resonant Soft-Switching Converter With Capacitive Doubler

Electrification of power take-off (ePTO) system is an effective way to minimize the fossil fuel consumption from heavy duty electric vehicles, where a high gain dc/dc converter is needed to integrate PV/fuel-cell. Popular high-gain dc/dc converters such as PWM type, clamped and unclamped quasi-resonant converters cant serve such applications as they fail to achieve high-efficiency, wide load and input voltage range for soft-switching, constant switching frequency and high transformer utilization (TUF) simultaneously. In this paper, a LCL series resonance based high-gain load resonant dc/dc converter is proposed to eliminate the above-mentioned drawbacks. A series resonant tank in the converter is able to adapt tank current in proportion to load demand leading to minimum losses and high TUF. Further, energy is stored in the series and parallel resonant inductors, in proportion to load demand and constant load voltage respectively, ensures soft-switching of the converter through full load to light load conditions. On the other hand, proposed converter operates with constant switching frequency to adopt simple PWM modulation to regulate load voltage against input and load disturbances. This paper presents operation, analysis, modeling and design of the proposed converter. Hardware setup has been mounted and tested to verify he proposed theory.

A Strong Misalignment Tolerance Dual-Channel Coupler for Wireless Power Transfer System

In order to improve the transmission performance of the wireless power transfer (WPT) system under misaligned conditions, a novel type of dual-channel DDP type transmitter coil is proposed inspired by the traditional LCC compensation circuit and DD coil. The proposed DDP coil is a combination of DD coil and P coil, which jointly establishes the main flux for magnetic coupling and power transmission. At the same time, the P coil also acts as the resonant inductor of the LCC compensation circuit of the WPT system. When the system parameters are well designed, we can achieve relatively more stable output current during the offset of the primary and secondary sides. Experimental results indicate that when the misalignment varies from 0 m to 0.15 m, the output current variation range is 2.92 A to 3.68 A, the current fluctuation rate is 11.5%. Compared with the traditional DD coil with LCC topology, the proposed dual-channel transmitter DDP coil shows better performance in misalignment tolerance.

Analysis of Slip Ring Induction Motor Drive Using Slip Power Recovery Scheme with Inverter and Chopper Control for Id Fan in Power Plant

Abstract: Induction motors are used as industrial drive and for various applications in power plant due to their rugged, robust and simple construction as well as low cost. The speed control of SRIM is dexterous by slip power recovery scheme consisting of inverter control, chopper control, and rotor resistance control techniques. This paper presents the boost in the performance characteristics and energy saving of SRIM drive by inverter and buck-boost chopper based slip power recovery scheme (SPRS). The simulation model of a WRIM drive using inverter and based buck-boost chopper control has been executed in the Simulink platform. The simulation results using inverter and chopper control have been studied. The active power and reactive power have been taken as parameter for analyzing the energy saving by the drive. The simulation result has shown that inverter chopper control SPRS large amount of energy saving.

An Extended Model for Ripple Analysis of 2–4 Phase Resonant Electrostatic Induction Motors

Electrostatic motors are promising forms of actuation for future robotic devices. The study of their different implementations should accelerate their adoption. Current models for resonant electrostatic induction motors were found not to be able to properly describe their behavior, namely, with regard to changes with position. This paper reports a new analytical model for these motors, aiming to address this issue. The model is based on identification of all capacitance harmonics, through a simplified method. Using these, equations for different motor parameters, notably, thrust force, were obtained and compared to previous literature. The new equations model position dependent properties, such as force ripple. The outputs of this model were validated through experimentation with a prototype, with the results confirming the new model better describes motor behavior. An analysis into how to decrease this ripple was also discussed and tested. We concluded that the use of a higher number of harmonics resulted in a much more accurate model, capable of adequately characterizing motor outputs with changes in position.

Procedure for the Accurate Modelling of Ring Induction Motors

This paper proposes a procedure for the accurate modelling of the ring induction motors (RIMs), based on the Monte Carlo (MC) method and the relations presented in the relevant metrology guidelines. Modelling was carried out based on the measured data for the torque-slip characteristic (TSC) and using the equivalent circuit for the RIM. The parameters included an extended Kloss equation (EKE) and the associated uncertainties were determined using the MC method. The polynomial procedure was applied as a numerical tool to complement the MC method to determine the power losses in the stator iron and the relevant uncertainty. This is in line with international standards for the theory of uncertainty application in the field of engineering. The novelty of this paper refers to the accurate modelling of the RIMs obtained by determining the corresponding uncertainties. The procedure presented in this paper was developed based on the assumption that the parameters of the equivalent circuit are independent of the temperature, influence of core saturation, and the phenomenon of current displacement. Our procedure can be successfully used for both the theoretical calculations related to the modelling of the RIMs, and in practical applications involving detailed measurements and the corresponding uncertainties. The use of the MC method allowed for significant improvement in the modelling results, in terms of both the TSC and EKE.

A Novel Repetitive High-Voltage Resonant Pulse Generator for Plasma-Assisted Milling

This article puts forward a high repetition rate and high-voltage resonant pulse generator for plasma-assisted milling. This circuit uses only one semiconductor switch with an antiparallel diode and works in the resonant mode with the help of a resonant inductor, a resonant capacitor, and a pulse transformer to generate high-voltage pulses. An equivalent circuit of the proposed topology considering parasitic elements is established. Based on the equivalent circuit, the working principle of the pulse generator is analyzed in detail. In order to verify the theoretical analysis and circuit operation, a laboratory prototype with a 150-V dc input is implemented. The pulse repetition rate can be adjusted from 5.32 to 18.90 kHz, and the peak output voltage correspondingly varies between 8.84 and 11.7 kV. The pulse generator is used to drive a dielectric barrier discharge plasma-assisted milling chamber. Experimental results show that the pulse generator can work stably.

A Case Study: Influence of Circuit Impedance on the Performance of Class-E2 Resonant Power Converter for Capacitive Wireless Power Transfer

The evolution of power electronics led to rapid development in wireless charging technology; as a result, a single active switch topology was introduced. The present market utilizes inductive wireless power transfer (IPT); because of the disadvantages of cost, size, and safety concerns, research on wireless power transfer was diverted towards capacitive wireless power transfer (CPT). This paper studies the optimal impedance tracking of the capacitive wireless power transfer system for maximum power transfer. Compared to prior methods developed for maximum power point tracking in power control, this paper proposes a new approach by means of finding impedance characteristics of the CPT system for a certain range of frequencies. Considering the drone battery as an application, a single active switch Class-E2 resonant converter with circular coupling plates is utilized. Impedance characteristics are identified with the help of equations related to the input and resonant impedance. The impedance tracking is laid out for various resonant inductors, and the difference in current peak is observed for each case. Simulations verify and provide additional information on the reactive type. Additionally, hardware tests provide the variation of input current and output voltage for a range of frequencies from 70 kHz to 300 kHz. Efficiency at the optimal impedance points for a resonant inductor with 50 μH and 100 μH are tested and analyzed. It is noted that the efficiency for a resonant inductor with 50 μH is 8% higher compared to the CPT with a 100 μH resonant inductor. Further hardware tests were performed to investigate the impact of frequency and duty cycle variation. Zero-voltage-switching (ZVS) limits have been discussed with respect to both frequency and duty cycle.

Laboratory setup for teaching resonant converters and induction heating

In this study, a laboratory prototype is implemented for electrical and electronics engineering students to have theoretical and practical knowledge about the resonant power conversion and induction heating systems. For this purpose, a safe low voltage induction heater laboratory prototype with full bridge series resonant inverter is set up and tested with different workpieces. Experimental studies for different load types are achieved and quality factor, resonant frequency, maximum inverter current, inductance and resistance values are investigated. The unique value of this study is that students will have knowledge about second order circuits, resonant converters and learn what conditions affect the circuit parameters of an induction heater. The properties of induction heaters will also be learned on this circuit.

Air-Cored Resonant Induction Machines: Comparison of Capacitor Tuning Criteria and Experimental Validation

The operation of air-cored resonant induction machines is very sensitive to the tuning of the capacitors. By using the equivalent circuit equations, this article explores in detail the machine performances under four different tuning criteria: (a) both stator and rotor capacitors resonating with the stator and rotor self-inductances; (b) both capacitors resonating with the leakage inductances; (c) stator capacitors tuned to compensate for the overall stator terminal reactance and no rotor capacitors; (d) stator capacitors only to cancel out the machine ideal input reactance neglecting resistances, which is the new option introduced in this article. Extensive comparisons of all tuning options in torque, efficiency, power factor, capacitor size, and feasibility are presented and their performances are compared with a pure air-cored induction machine without capacitors. Analytic expressions for the maximum efficiency and maximum torque and related slip values are also derived as functions of the machine parameters, which provides a valuable tool for design optimization. A numerical case study based on parameters of a real air-cored induction machine is discussed and the article includes the first experimental validation to be carried out on a spinning air-cored resonant induction machine prototype. Results show that using only stator capacitors to compensate for the machine equivalent terminal reactance can be a practical choice to achieve both high torque and high efficiency and avoid rotor capacitors.

CLL Resonant Converter With Secondary Side Resonant Inductor and Integrated Magnetics

A <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant converter with transformer–inductor-integrated magnetics is proposed. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLL</i> resonant converter is derived by placing the resonant inductor of an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter on the secondary side of the transformer. In comparison with an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> resonant converter, the circulating current associated with the magnetizing current of the transformer is removed from the resonant inductor. More importantly, the phase difference between the flux in the magnetic cores of the transformer and the resonant inductor becomes larger. Therefore, the flux of the transformer and inductor can be cancelled with each other, resulting in a reduced loss and volume of the magnetic core. A novel structure is proposed to integrate the transformer and inductor with integrated winding structures. Detailed analysis and optimized design of the integrated transformer–inductor are presented. The effectiveness and feasibility of the proposed solutions are verified with simulation and experimental results.

A soft-switching high gain DC–DC converter for renewable energy systems

ABSTRACT In order to improve the efficiency of high gain DC-DC converter using MOSFET as switching device, a novel zero-voltage soft-switching high gain DC-DC converter is presented. A main switch tube is used to replace the output diode in the conventional boost converter, and an auxiliary network is added to make the two switches realise true ZVS soft turn-on and all diodes realise true ZCS soft turn-off, which improves the efficiency and effectively suppresses the negative effect of diode reverse recovery. Furthermore, the output end of the converter is composed of three output capacitors in series, which avoids the converter working at the limit duty cycle, increases the voltage gain and reduces the switch voltage stress. Therefore, MOSFET with low voltage level and low on resistance can be selected as switching devices. The resonant capacitor and leakage inductance are used to reduce the current at the turn-off time of the switch. The operating principle and steady-state characteristics of the converter are analysed in detail. The design idea of the main parameters is given, and the efficiency and loss of the converter are evaluated. Finally, the experimental results on a 100 W prototype show that the efficiency reaches 95.79% at rated power.