Resonant Network Research Articles

Resonant wireless charging scheme

In order to reduce the number of switching devices and passive components in the hybrid topology charging system based on resonant power transmission technology, and simplify the control strategy of primary and secondary sides, a hybrid self switching resonant topology based on LCL-LCL/S is proposed. The structure does not need primary and secondary side communication and adds any passive components, and only changes the topology network through the self switching operation of LCL structure can be realized constant current and constant voltage switching of wireless charging system. Then, according to the characteristics of battery charging curve, resonant current threshold and voltage jump threshold, a parameter optimization design method for hybrid resonant topology network is proposed, which can avoid the parameter uncertainty caused by the limitation of empirical selection of resonant network parameters, and provide theoretical basis for parameter selection. In the constant current and constant voltage mode, the input impedance is pure resistance, and the zero phase angle(ZPA) is between the input current and the voltage. The experimental results show that the hybrid self switching wireless charging system with optimized resonant network parameters has better constant current and constant voltage output characteristics. The system realizes ZPA and constant frequency soft switching characteristics, which meets the requirements of constant current and constant voltage charging.

A High Power Density Wide Range DC–DC Converter for Universal Electric Vehicle Charging

This article presents a single stage isolated bidirectional DC–DC converter comprising of LCL-T resonant network for universal electric vehicle (EV) charging. Fixed frequency operation along with phase-shift control enables easier design of passive components, while achieving high efficiency across wide output voltage range. Furthermore, to increase the switching frequency and consequently the power density, gallium nitride (GaN) switches are explored in the proposed solution. In order to facilitate use of commercially available 650 V GaN transistors, a multi-level inverter and a reconfigurable rectifier architecture is utilized along with LCL-T resonant network, accommodating an input voltage of 800 V, generated from an universal three phase ac input supply, and an output voltage ranging from 150 V to 950 V catering to large variation of battery voltages from different vehicle manufacturers. The constant input voltage-to-output current gain property of LCL-T network, along with an efficient phase-shift modulation proposed in this paper enable soft switching of all transistors with minimum circulating currents over constant current (CC), constant power (CP), and constant voltage (CV) modes of battery charging. Experimental results are provided for a single-phase DC–DC converter prototype utilizing 650 V GaN transistors operating from an 800 V DC bus and providing a very wide output voltage from 150 V to 950 V at 6.6 kW maximum power at a constant switching frequency of 500 kHz. The prototype achieves two peak efficiency points of 98.2% and maintains <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$&gt;$</tex-math></inline-formula> 97% efficiency across the entire output voltage range at a power density of 120 W/in <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> (7.3 kW/L).

Passive Paralleling of Multi-Phase Diode Rectifier for Wireless Power Transfer Systems

To improve the power level of a diode rectifier, a multi-phase diode rectifier can be employed to increase the current rating. This brief proposes a passive current balancing method for a multi-phase diode rectifier in a series-series compensated wireless power transfer system. For an N-phase diode rectifier, the receiver-side compensating capacitance is split into N branches, forming a parallel resonant network with the newly added parallel resonant inductors. The circulating currents can be greatly suppressed by the parallel resonant network. The resonant inductors only withstand differential-mode currents, which are small. Thus, these inductors are small and low-cost. Experimental results reveal that the proposed method can well balance the phase currents of the three-phase diode rectifier.

Resonant Network-Based MVDC Circuit Breaker Topologies With Fast Current Breaking Capability

This paper presents two improved circuit breaker (CB) topologies based on resonant networks for medium voltage DC (MVDC) applications, such as shipboard power distribution and subsea oil and gas production. The topologies feature simple LC resonant networks that efficiently suppress fault current in just a few tens of microseconds, making them suitable for integration with existing solid-state or hybrid DC CB. Moreover, they also help to minimize the CB energy and reduce (if not eliminate) the requirement for protection devices like surge arresters during fault events. The proposed topologies are first tested using Typhoon Hardware-in-the-Loop (HiL) simulations at 1.2 MW (6 kV, 200 A) power levels and thyristor-based solid-state circuit breakers (SSCB). Then, scaled-down laboratory prototypes, also based on thyristor-based SSCB, are experimentally validated. The results show that both topologies quickly bring the current of the CB’s main switch to 0 A. The main circuit pathway requires only a small inductor and switch, resulting in a steady-state efficiency of >99.9%. The resonant network-based design allows for a fast response time of less than 50 μs using a simple and low-cost auxiliary circuit, eliminating the need for complex charging circuitry and protection devices typically used to suppress voltage surges during faults.

Resonant Scattering-Inspired Deep Networks for Munition Detection in 3D Sonar Imagery

Resonant Scattering-Inspired Deep Networks for Munition Detection in 3D Sonar Imagery

An Intrinsic Faulty Feeder Selection Approach for Resonant Grounded Power Distribution Networks in Bushfire Prone Areas Using Zero-Sequence Current Ratio

An Intrinsic Faulty Feeder Selection Approach for Resonant Grounded Power Distribution Networks in Bushfire Prone Areas Using Zero-Sequence Current Ratio

Novel Zero-Voltage Zero-Current Transition Buck Converter With Minimal Impact of Active Auxiliary Cell on Overall Dynamics

This paper presents a novel zero-voltage zero-current transition DC/DC buck converter, which uses an active auxiliary resonant network to achieve soft switching operation of semiconductor switches and soft-recovery of power diodes over wide output power range and offers high efficiency. The auxiliary cell in the proposed converter does not cause any additional current stress on the semiconductor switches and has minimal impact on overall dynamics of the converter. Steady-state performance of the converter has been presented with detailed theoretical analysis of all operating modes. The design of auxiliary cell components and development of small signal model of the converter have been carried out from the mathematical equations depicting its dynamic behaviour. A closed loop voltage mode controller with a type III compensator has been developed for the converter to achieve the desired transient response under the influence of external disturbances. Power loss analysis and superiority of the proposed converter over other conventional configurations are also presented here. Finally, soft-switching behaviour and step-input transient response of the converter are verified by hardware experimentation on a 150W, 100 kHz prototype model. The experimental measurements have successfully validated the theoretically predicted behaviour of the converter.

Frequency offset suppression method for wireless power transfer based on nonlinear resonant network

SummaryIn magnetically resonant wireless power transfer (MR‐WPT) systems, transmitter, and receiver usually operate at the same resonant frequency. However, parameters of inductor, capacitor, or other components are susceptible to changes due to environmental factors and cause resonant frequency deviation. This would lead to decrease of transmission performance. To solve the problem, a wireless power transfer system based on a nonlinear compensation network is proposed to suppress frequency offset. The modeling of the nonlinear MR‐WPT system is first established. On this basis, the mathematical equation of the equivalent nonlinear circuit is deduced and the amplitude‐frequency response characteristics are analyzed. The influence of inductance parameter on the nonlinear characteristic is studied. Furthermore, the effects of excitation amplitude, compensation capacitance, load, and magnetic ring turns on the operating characteristics of the nonlinear resonant circuit are analyzed. The proposed nonlinear resonant wireless power transfer system is constructed and is experimentally studied. Compared with the traditional linear MR‐WPT system, the results show that frequency offset can be effectively suppressed, which ensures efficient transmission performance with the proposed method.

Insulation Parameter Online Measurement Technology Based on Extended Zero-Sequence Circuits for Resonant Grounding Distribution Networks

To eliminate the measurement errors of insulation parameters caused by the internal impedance of VT (voltage transformer) and the damping resistance in resonant grounding distribution networks, a new online measurement technology based on an extended zero-sequence circuit is proposed. A constant current signal with variable frequency is injected into distribution network through a VT, and the return voltage is measured from another unloaded VT. An extended zero-sequence circuit is established to ensure that the injected current and the return voltage directly act on the insulation branch to ground; thus, the influence of the VT internal impedance can be eliminated. The resonance frequency is obtained according to the phase difference between the injected current and the return voltage, and the measurement error caused by damping resistance can be eliminated. Then, the capacitance to ground and leakage conductance can be accurately calculated. A measuring device based on the proposed technology was developed, and tests were carried out on a 10-kV distribution network laboratory and an actual 10-kV substation. The test results show that the proposed method has high measurement accuracy. The measurement process does not require a power interruption, and it does not affect the normal operation of the power system.

A comprehensive review of control techniques for compensating the fault current in resonant grounded distribution networks: From the perspective of mitigating powerline bushfires

Powerline faults are responsible for major bushfires around the world where arcs provoked from ground faults are common causes for igniting such fires. The grounding techniques (mainly resonant grounding) used in distribution substations and arc suppression devices play a crucial role for compensating fault currents in order to extinguish arcs so that the likelihoods of powerline bushfires are significantly reduced. Though passive arc suppression devices (e.g. Petersen coils) are extensively used for compensating the reactive component of the fault current, the active component of this current is still large enough to ignite the fire in bushfire prone areas for which active arc suppression devices are recently used. These active arc suppression devices incorporate residual current compensation inverters and the full compensation of the fault current rely on the control scheme of these inverters. This paper comprehensively reviews different control schemes that are used for compensating the fault current in resonant grounded power distribution systems. The existing control schemes are discussed in terms of the model used during the controller design process, loop structures, control block diagrams, and performance analysis frameworks (i.e. the type of fault impedances). It is worth mentioning that faults on resonant grounded power distribution networks exhibit the characteristics of high impedance faults and it important to consider this aspect for performance analysis of the control scheme. This paper also covers a brief overview of different grounding techniques used for mitigating fault currents and finally, the challenges with the existing controllers are identified in terms of extinguishing powerline bushfires. The comprehensive review motivates and guides future research activities on developing more efficient fault compensation techniques.

Optimal Design of Resonant Network for Resonant Converter

The dc transformer based on <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter is widely researched in the dc microgrid due to its excellent bidirectional power transfer capacity. Many resonant network design methods assume that the resonant current is constant during the deadtime. It may lead to hard switching or large conduction loss. Besides, the effects of deadtime on soft switching have not been closely analyzed. This article proposes an optimized design method to minimize conduction losses while achieving zero voltage switching, and it can easily obtain the optimal region and deadtime selection range. Parametric design and deadtime selection principles are derived based on the time-domain models, and then the design method and corresponding procedure are developed. Finally, a 4-kW 500-kHz <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">CLLC</i> resonant converter prototype is built to verify the feasibility of the proposed optimal design method.

A High-Voltage Capacitor Charger Based on a Novel LCCL Resonant Converter

High-voltage/high-power capacitor chargers are primarily interested in many industrial applications. Resonant converters have been a proper choice in such applications because of their advantages. However, the performance of the resonant converter is highly affected by the parasitic elements of the high-voltage/high-power transformer. Also, a short-circuit condition is a frequent event in high-voltage applications, so that the resonant converter should be robust against the short-circuit condition. This article presents a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCCL</i> resonant converter with current-source characteristics used as a high-voltage capacitor charger. The proposed resonant converter eliminates the undesirable effect of the stray capacitance in high-voltage devices and is robust against the short-circuit condition inherently. It also provides a semitrapezoidal resonant current wave, which produces a lower crest factor. Furthermore, a frequency-sweep operation is applied, which has advantages in reducing the resonant current's peak value and the resonant network's size. Simulation results show a satisfactory performance of the proposed resonant converter. Moreover, experimental results confirm the effectiveness of the proposed resonant converter in the application of capacitor charging.

An Interleaved Soft Switched High Step-Up Boost Converter With High Power Density for Renewable Energy Applications

In this article, a novel soft switched interleaved boost structure with a simple auxiliary circuit is proposed which is suitable for stand-alone loads or ac grid applications. In this topology, coupled inductors and switched capacitor cells of parallel modules are merged to obtain high voltage conversion ratio. The converter also has the capability of adding extra switched capacitor cells to attain very high voltage gain. To provide soft-switching condition in the wide range of output power, a new zero-voltage transition auxiliary circuit is employed which is responsible for soft switching of both phases and benefits from low conduction losses, the minimum number of semiconductor elements, and only one auxiliary gate-driver. These merits provide very high efficiency at both full-load and light loads. More importantly, no auxiliary magnetic components are utilized by taking advantage of the leakage inductance of coupled inductors for the resonant network. All semiconductor components operate under soft switching alleviating the reverse recovery problem and switching losses. Besides, the converter benefits from common ground between input and output which simplify voltage feedback. The experimental results of the interleaved converter prototype with 400-V output voltage at 400 W and 100 kHz switching frequency are provided. The full load efficiency of 98% was achieved and the power density was observed 1.9 W/Cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> .

Sliding mode synchronization of complex resonant Josephson junction network

In this paper, we discuss a sliding mode synchronization control strategy in complex resonant Josephson junction network with two sliding mode techniques. First, an integral sliding mode controller is designed by taking into consideration of integral sliding surface along with its switching function in order to find an integral sliding mode control law for synchronization between the drive and response systems. For this controller, the error variables between the drive and response system is selected to obtain the appropriate sliding variable. Then, a terminal sliding mode controller is obtained by selecting an appropriate sliding surface in order to obtain synchronization. We compare the two control synchronization strategies to verify which of the techniques are faster, accurate and posses chattering avoidance properties. Finally, we verify with respective numerical experiments along with the conclusions and discussions.

ZVT High Step-Up Boost Converter With Wide Input Voltage and Wide Output Power for Renewable Energy Applications

In this article, a high-efficiency, high step-up dc–dc converter is introduced by utilizing a new soft-switching circuit based on the zero-voltage transition (ZVT) technique. Soft-switching performance is independent of the output load and input voltage. The simple auxiliary circuit benefits from a low number of components. The resonant circuit comprises merely one switch and one small capacitor, and in comparison to the existing ZVT high step-up converters, no extra auxiliary diode and resonant inductor are used to provide soft switching. The proposed auxiliary circuit can be applied to coupled inductor (CI)-based step-up topologies, because of exploiting the leakage inductance of the CI cell in the resonant network. Providing soft-switching performance for all the semiconductor elements alleviates the reverse recovery and switching losses, which considerably enhances the efficiency. The proposed topology is a competitive structure in terms of efficiency, voltage gain ratio, and the number of components due to the mentioned features. The theoretical results are validated on a 200-W laboratory prototype with a 400-V output voltage.

A soft-switching capacitive wireless power transfer system with asymmetric bilateral LCL resonant network

This paper presents a soft-switching capacitive power transfer (CPT) system based on asymmetric bilateral LCL resonant network for shipborne charging base station applications. CPT system is composed of high frequency inverter, resonant network and coupling mechanism. In this paper, a double E-class inverter which can realize constant power output and soft-switching operation of switching tube is adopted. Based on the analysis of asymmetric bilateral LCL resonant network, a method for calculating the parameters of resonant network parameters with constant power transmission is designed. Finally, a simulation model is established by using the system parameters obtained from the application, and the simulation results verify the constant power output characteristics of the proposed CPT system.

Review of research progress and application of magnetic resonant WPT technology

Compared with traditional contact charging, wireless power transfer technology (WPT) has the advantages of convenience and flexibility, strong environmental adaptability, safety and reliability, and has attracted the research interest of a large number of researchers. Among them, the resonant wireless power transmission technology has good application value because of its long transmission distance and high-efficiency energy transmission characteristics, and is one of the important development directions in the field of wireless power transmission. This paper mainly introduces the concept and classification of wireless power transmission technology, reviews the development history of resonant WPT technology, and summarizes the basic structure and working principle of resonant WPT technology, hot technical issues, and product development and practical application status. It is pointed out that the resonant network including the non-contact transformer is the key to restrict the whole resonant WPT system.

Hybrid Waveguide Feed Network for Aperiodic Subarray Beamforming

In this letter, a hybrid waveguide feed network for an aperiodic subarray beamforming antenna is presented. The feed structure is divided into vertical and horizontal parts. Vertical parts have inclined slots with a reduced-height waveguide, and the horizontal part has unequal <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -plane septum power dividers to achieve a compact feed network with acceptable electrical characteristics. The angle of each inclined slot and the position of each septum were designed for amplitude weighting and in-phase characteristics. For comparison, a simple resonant feed network without septum power dividers (i.e., with waveguides and inclined slots) was simulated to access the effectiveness of the proposed network. The proposed structure was fabricated using computer numerical control milling and diffusion bonding. The input reflection coefficient was less than −15 dB, and the transmission phase difference between 20 ports was less than 72° within a bandwidth of 2.4%. This feed network design has potential applications in electronically scanned arrays and subarray antennas for a limited field of view.

Passive Current Sharing of a Multiphase Inverter Based on Parallel Resonance

To balance the phase output currents of a multiphase inverter, negatively coupled inductors (NCIs) can be used to achieve a larger differential mode (DM) loop impedance than the common mode (CM) loop impedance. For a good current sharing effect, the inductances of the NCIs should be large, leading to bulky size and cost ineffectiveness, which should be avoided in high-power applications. This article proposes a novel current balancing method based on parallel resonance. A parallel resonant network (PRN) is inserted between any two phases. With <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta $</tex-math></inline-formula> -Y transform, the inductor common point and the capacitor common point are generated, either of which can be used as the CM output node. For a series–series compensated wireless power transfer system, part of the existing compensating capacitance can be employed to form PRNs with the added parallel inductors. The DM currents are suppressed by the large impedance of the PRNs. Compared with the existing method, the inductances of the NCIs can be greatly reduced to achieve better current balancing performance. The added parallel inductors are of small current ratings, which are only visible to DM currents. A prototype is implemented to validate the proposed method.

Synchronization Strategy Based on Resonant Current Detection for Bidirectional Wireless Charging System

Bidirectional wireless power transfer (BWPT) greatly improves the reliability of power supply. However, wireless communication between the primary and pickup controllers is usually required to transmit load information, which has time delay and is easily interfered by electromagnetic fields. Existing solutions to avoid the use of communication can be divided into three categories: additional DC/DC circuit, primary side bridge control and secondary side bridge control. Compared with the other two methods, the secondary side bridge control has low loss and good robustness. But it usually requires Phase-Locked Loop (PLL) to eliminate the frequency error between primary and secondary side bridges, which increases the complexity. In this paper, a constant current control strategy without communication is proposed. It is based on the secondary side bridge control and the switching sequence of the secondary side bridge is periodically synchronized according to the phase of the resonant current. It works robustly without the need for additional hardware such as PLL or Multiplier. The harmonic sensitivity analysis, parameter optimization design and stability analysis are carried out to improve the control efficiency. Experimental results based on a 1kW prototype with dual LCC resonant network are presented to verify the effectiveness of the proposed control strategy.