Coupling Coils Research Articles

Review on the Applications of Intelligent Algorithm in Wireless Charging System for Electric Vehicles

This paper presents a comprehensive review of the intelligent algorithms (IAs) based optimization of electric vehicle (EV) wireless charging. First, a general overview of EV wireless charging system is introduced in terms of the compensation circuit, coupling coils, and control strategies, followed by the potential application of IAs. Then, the optimization target, parameter optimization, and structure design of the compensation topologies based on IAs are elaborately expounded by citing current research findings. Subsequently, the IAs are deeply explored for optimizing the systematic parameters, structural geometries, and coupling coils. Then, the IA-based research on the control strategies in the wireless charging system is discussed in detail from three aspects, including power controlling, efficiency optimizing, and parameter tracking. Finally, the prospects for the application of IAs to the EV wireless charging system are summarized and delineated. This paper will be highly beneficial to research entities as a ready reference for the wireless charging system of EVs, with information on IA-based system design.

A novel Q-switch technique for ringing-down dissipation of borehole NMR measurement

Abstract Nuclear Magnetic Resonance (NMR) is a crucial logging technique for the unconventional and complex reservoir evaluation. However, the echo spacing is always an issue of borehole NMR measurement, which limits the performance of NMR tools to acquire the short relaxation components. In this paper, we proposed a novel Q-Switch technique aiming at breaking through the limitation of dead-time of borehole NMR logging tool, and to achieve much shorter echo spacing. Instead of using resistors in parallel with the radio-frequency (RF) coil to reduce the active dead-time, an inductive coupling Q-Switch circuit was introduced to decrease the ringing-down time significantly after transmitting the RF pulses with high voltage. The Q-Switch circuit consists of inductive coupling coil, capacitors, resistors and active high-voltage MOSFETs. The ringing-down time of RF system was decreased by at least 10 times compared to the system without using proposed Q-switch scheme, leading to echo spacing lower to 0.3 ms under the condition with resonant frequency lower to 500 kHz. Both simulations and experiments were in great agreements, validating the feasibility and efficiency of proposed Q-switch scheme, which proved to be promising in the borehole NMR applications.

An Overview of Key Technologies for Wireless Charging Systems for Unmanned Aerial Vehicles

With the demand for an intelligent and modernized society, the application of UAVs has become increasingly widespread. However, their performance is limited by battery capacity constraints, making UAV wireless charging an effective solution for prolonging operational time. This thesis focuses on the research of shutdown technology in UAV wireless charging systems. Firstly, it introduces the current research status in this field. It then comprehensively covers the principles of wireless energy transmission, with a particular focus on magnetic coupling resonance. Next, it addresses key issues such as compensation topology mechanisms and coupling coil circuit analysis. Following that, a technical analysis is conducted based on hover charging and landing charging, respectively. Finally, the thesis summarizes the current progress of UAV wireless charging and provides an outlook on areas for improvement in related research.

Research on the sensing properties and vibration reduction performance of self-sensing self-tuning magnetic fluid damper

Abstract The semi-active control damping system has gained popularity due to its quick response time and versatility. However, external sensors are susceptible to environmental interference, affecting system reliability and increasing complexity and maintenance costs, restricting their use. To address this, a self-sensing self-tuning magnetic fluid damper (SSMFD) is proposed. The vibration-measuring induction coil is wound on the damper to sense the magnetic fluid vibration information in real time, and the vibration signal is communicated to the self-tuning control circuit. The control circuit calculates and determines the dominant frequency of structural vibration, then outputs the relevant current signal to set the damper’s natural frequency to track the excitation frequency, resulting in self-tuning vibration reduction. First, the self-sensing unit’s output induced electromotive force model is created, followed by an expression of the damper’s natural frequency, indicating that the self-sensing unit can achieve self-tuning vibration reduction by tracking the excitation frequency. The multi-field coupling simulation model of the magnetic fluid damper is generated, and the induction coil coupling mode and damper excitation angle are defined to obtain the maximum induced voltage. Finally, an experimental platform was developed to assess the damper’s self-sensing and self-tuning vibration reduction performance. The experimental results show that the proposed SSMFD performs well, making it a feasible solution for achieving self-sensing and self-tuning vibration reduction.

Research on Active Power Loss Distribution of Components in Magnetic Coupling Wired Drill Pipe

Abstract The magnetic coupling wired drill pipe achieves high-speed information transmission by installing cable at the rod and embedding magnetic couplers at the joints. However, significant energy attenuation in these connected wired drill pipes necessitates the addition of relay circuit compensation every few hundred meters, increasing system complexity and cost. The equivalent circuit of magnetic coupling wired drill pipe can be regarded as a series connection of a coaxial cable line, high-frequency transformer, and terminal load. Exploring better wired drill pipe parameters to distribute signal power across different frequencies will optimize power at the terminal load and improve relay distance. This research establishes a mathematical model for active power distribution in magnetic coupling wired drill pipes based on circuit analysis. The model’s accuracy is validated through circuit simulation and numerical analysis. Reducing signal energy attenuation in the cable and coupler is achieved by increasing the coil coupling coefficient, reducing the coil resistance, and altering the characteristic impedance of the coaxial cable. This research provides a theoretical tool for analysing active power loss distribution of components in wired drill pipe.

Dynamic Wireless Charging of Electric Vehicles Using PV Units in Highways

Transitioning from petrol or gas vehicles to electric vehicles (EVs) poses significant challenges in reducing emissions, lowering operational costs, and improving energy storage. Wireless charging EVs offer promising solutions to wired charging limitations such as restricted travel range and lengthy charging times. This paper presents a comprehensive approach to address the challenges of wireless power transfer (WPT) for EVs by optimizing coupling frequency and coil design to enhance efficiency while minimizing electromagnetic interference (EMI) and heat generation. A novel coil design and adaptive hardware are proposed to improve power transfer efficiency (PTE) by defining the optimal magnetic resonant coupling WPT and mitigating coil misalignment, which is considered a significant barrier to the widespread adoption of WPT for EVs. A new methodology for designing and arranging roadside lanes and facilities for dynamic wireless charging (DWC) of EVs is introduced. This includes the optimization of transmitter coils (TCs), receiving coils (RCs), compensation circuits, and high-frequency inverters/converters using the partial differential equation toolbox (pdetool). The integration of wireless charging systems with smart grid technology is explored to enhance energy distribution and reduce peak load issues. The paper proposes a DWC system with multiple segmented transmitters integrated with adaptive renewable photovoltaic (PV) units and a battery system using the utility main grid as a backup. The design process includes the determination of the required PV array capacity, station battery sizing, and inverters/converters to ensure maximum power point tracking (MPPT). To validate the proposed system, it was tested in two scenarios: charging a single EV at different speeds and simultaneously charging two EVs over a 1 km stretch with a 50 kW system, achieving a total range of 500 km. Experimental validation was performed through real-time simulation and hardware tests using an OPAL-RT platform, demonstrating a power transfer efficiency of 90.7%, thus confirming the scalability and feasibility of the system for future EV infrastructure.

Optimization of coupling coils for downhole magnetic resonance wireless energy transmission system

Abstract In drilling engineering, resonant wireless energy transmission technology can effectively solve the problem of frequent charging or battery replacement of cable-less electronic tools downhole. However, due to the narrow space, high temperature, and high pressure inside the oil well, as well as the complex environment where oil, water, gas, and sand coexist, the traditional coil shape is not applicable. Therefore, spiral coils with inner and outer casing are usually used. However, in practice, due to the complex downhole environment, resonant wireless energy transmission coupling devices often encounter difficulties when nested downhole, thus affecting the transmission efficiency. To solve these problems and ensure transmission efficiency, a novel coil coupling model is proposed in this paper, and the power and efficiency expressions of the coupled electrical energy transmission system are derived. Subsequently, the spiral cylinder and the novel coil were simulated and analyzed using COMSOL Multiphysics software. The experimental results show that the model maintains a good transmission efficiency and improves the nesting effect in a complex downhole environment. This study provides a valuable reference for the optimization and design of wireless energy transmission systems.

Coupled stack-up volume RF coils for low-field open MR imaging.

Low-field open magnetic resonance imaging (MRI) systems, typically operating at magnetic field strengths below 1 Tesla, has greatly expanded the accessibility of MRI technology to meet a wide range of patient needs. However, the inherent challenges of low-field MRI, such as limited signal-to-noise ratios and limited availability of dedicated radiofrequency (RF) coils, have prompted the need for innovative coil designs that can improve imaging quality and diagnostic capabilities. In response to these challenges, we introduce the coupled stack-up volume coil, a novel RF coil design that addresses the shortcomings of conventional birdcage in the context of low-field open MRI. The proposed coupled stack-up volume coil design utilizes a unique architecture that optimizes both transmit/receive efficiency and RF field homogeneity and offers the advantage of a simple design and construction, making it a practical and feasible solution for low-field MRI applications. This paper presents a comprehensive exploration of the theoretical framework, design considerations, and experimental validation of this innovative coil design. We demonstrate the superior performance of the coupled stack-up volume coil in achieving 47.7% higher transmit/receive efficiency and 68% more uniform magnetic field distribution compared to traditional birdcage coils in electromagnetic simulations. Bench tests results show that the B1 field efficiency of coupled stack-up volume coil is 57.3% higher compared with that of conventional birdcage coil. The proposed coupled stack-up volume coil outperforms the conventional birdcage coil in terms of B1 efficiency, imaging coverage, and low-frequency operation capability. This design provides a robust and simple solution to low-field MR RF coil design.

Review of Compensation Topologies Power Converters Coil Structure and Architectures for Dynamic Wireless Charging System for Electric Vehicle

The increasing demand for wireless power transfer (WPT) systems for electric vehicles (EVs) has necessitated advancements in charging solutions, with a particular focus on speed and efficiency. However, power transfer efficiency is the major concern in static and dynamic wireless charging (DWC) design. Design consideration and improvements in all functional units are necessary for an increase in overall efficiency of the system. Recently, different research works have been presented regarding DWC at the power converter, coil structure and compensators. This paper provides a comprehensive review of power converters incorporating high-order compensation topologies, demonstrating their benefits in enhancing the DWC of EVs. The review also delves into the coupling coil structure and magnetic material architecture, pivotal in enhancing power transfer efficiency and capability. Moreover, the high-order compensation topologies used to effectively mitigate low-frequency ripple, improve voltage regulation, and facilitate a more compact and portable design are discussed. Furthermore, optimal coupling and different techniques to achieve maximum power transfer efficiency are discussed to boost magnetic interactions, thereby reducing power loss. Finally, this paper highlights the essential role of these components in developing efficient and reliable DWC systems for EVs, emphasizing their contribution to achieving high-power transfer efficiency and stability.

Mutual inductance identification of non-contact excitation system

Due to the presence of brush and slip ring in the excitation method of electrically excited synchronous motors, this article proposes a new excitation method - non-contact excitation system. This method transfers electrical energy from the stator to the rotor through magnetic coupling, replacing slip ring and brush. However, the magnetic coupling coils at the primary and secondary ends of the system will deviate, which will affect motor operation quality. In order to effectively reduce the changes caused by mutual inductance, this article proposes an improved particle swarm optimization algorithm for mutual inductance identification. This improved algorithm can effectively reduce the shortcomings of low accuracy and easy to fall into local optima in particle swarm optimization. Simulation and experimental results show that the improved particle swarm optimization algorithm can improve search accuracy.

Design and Analysis of Receiver Coils with Multiple In-Series Windings for Inductive Eddy Current Angle Position Sensors Based on Coupling of Coils on Printed Circuit Boards.

We present a method for improving the amplitude and angular error of inductive position sensors, by advancing the design of receiver coil systems with multiple windings on two layers of a printed circuit board. Multiple phase-shifted windings are connected in series, resulting in an increased amplitude of the induced voltage while decreasing the angular error of the sensor. The amplitude increase for a specific number of windings can be predicted in closed form. Windings are placed electrically in series by means of a differential connection structure, without adversely affecting the signal quality while requiring a minimal amount of space in the layout. Further, we introduce a receiver coil centerline function which specifically enables dense, space-constrained designs. It allows for maximization of the number of possible coil windings while minimizing the impact on angular error. This compromise can be fine-tuned freely with a shape parameter. The application to a typical rotary encoder design for motor control applications with five periods is presented as an example and analyzed in detail by 3D finite-element simulation of 18 different variants, varying both the number of windings and the type of centerline functions. The best peak-to-peak angular error achieved in the examples is smaller than 0.1° electrically (0.02° mechanically, periodicity 5) under nominal tolerance conditions, in addition to an amplitude increase of more than 170% compared to a conventional design which exhibits more than twice the angular error. Amplitude gains of more than 270% are achieved at the expense of increased angular error.

Coil Parameter Optimization Method for Wireless Power Transfer System Based on Crowding Distance Division and Adaptive Genetic Operators

In a Magnetically Coupled Resonant Wireless Power Transfer (MCR-WPT) system, the magnetic coupling coil is one of the key factors that determines the system’s output power, transmission efficiency, anti-offset capability, and so on. This article proposes a coil parameter optimization method for a wireless power transfer system based on crowding distance division and adaptive genetic operators. Through optimizing the design of decision variables, such as the numbers of transmitting and receiving coil turns, the spacings between transmitting and receiving coil turns, the inner radii of the transmitting and receiving coils, and the vertical distance of the coil, the best transmission performance can be achieved. This study improves the NSGA-II algorithm through proposing a genetic operator algorithm for average crowding and high crowding populations based on adaptive operators, as well as a genetic operator algorithm for low crowding populations based on information entropy. These improved algorithms avoid problems inherent to traditional genetic operators such as fixed genetic proportions, do not easily cause the algorithm to fall into a local optimal solution, and show better convergence in the ZDT1–ZDT3 test functions. The optimization design method in this article is not only independent of commercial software such as ANSYS Maxwell 2021 R1, but can also significantly improve the calculation speed compared with traditional simulation software.

A Novel Rotating Wireless Power Transfer System for Slipring with Redundancy Enhancement Characteristics

This study investigates the dynamics of wireless power supply technology under rotation and its system redundancy, aiming to design a redundant, rotating wireless power supply system. In order to satisfy specifications of redundancy and fault tolerance, the circuit design of the wireless power transmission system was developed, and a planar three-sector coil coupling mechanism was designed; finally, the stability and power output characteristics of the system were assessed under static and dynamic working conditions, and the results show that the maximum output power of the system can reach 3 kW and the efficiency is more than 91% under both static and dynamic working conditions. The study improved the rotating wireless charging system’s efficiency, which improves the energy utilization efficiency.

A digital twin for parallel liquid-state nuclear magnetic resonance spectroscopy

One approach to increasing nuclear magnetic resonance measurement sample throughput is to implement multiple, independent detection sites. However, the presence of radio frequency interference poses a challenge in multi-detector systems, particularly in unshielded coil arrays lacking sufficient electrical isolation. This issue can lead to unwanted coupling of inductive coils, resulting in excitation pulse interference and signal transfer among multiple detection sites. Here we propose a theoretical framework that combines electromagnetic simulation with spin-dynamic calculations. This framework enables the evaluation of coil coupling effects, the design of parallel pulse sequences to mitigate inter-channel coupling, and the separation of composite free induction decays obtained from multiple detectors. The parallel pulse compensation scheme was validated by a 2-channel parallel spectroscopy experiment. These results provide valuable insights for the design of parallel nuclear magnetic resonance hardware and for exploring the limits of parallelization capacity within a fixed magnet system.

Erratum to: Synthesis of a Simulation Model of Coupled Coils in an Electric Vehicle Wireless Charging System

Erratum to: Synthesis of a Simulation Model of Coupled Coils in an Electric Vehicle Wireless Charging System

Design and Optimization of Coil for Transcutaneous Energy Transmission System

This article presents a coil couple-based transcutaneous energy transmission system (TETS) for wirelessly powering implanted artificial hearts. In the TETS, the performance of the system is commonly affected by the change in the position of the coupling coils, which are placed inside and outside the skin. However, to some extent, the influence of coupling efficiency caused by misalignment can be reduced by optimizing the coil. Thus, different types of coils are designed in this paper for comparison. It has been found that the curved coil better fits the surface of the skin and provides better performance for the TETS. Various types of curved coils have been designed in response to observed bending deformations, dislocations, and other coupling variations in the curved coil couple. The numerical model of the TETS is established to analyze the effects of the different types of coils. Subsequently, a series of experiments are designed to evaluate the resilience to misalignment and to verify the heating of the coil under conditions of severe coupling misalignment. The results indicated that, in the case of misalignment of the coils used in artificial hearts, the curved transmission coil demonstrated superior efficiency and lower temperature rise compared to the planar coil.

Analysis of an Oscillatory System With Three Coupled Coils for Wireless Power Transfer

Analysis of an Oscillatory System With Three Coupled Coils for Wireless Power Transfer

Analysis and design of wireless power transfer system with anti-misalignment constant voltage output characteristics

PurposeThis study aims to solve the problem of high output voltage fluctuation and low efficiency caused by the misalignment of the magnetic coupling structure in the wireless charging system for electric vehicles. To address these issues, this paper proposes a dual LCC-S wireless power transfer (WPT) system based on the double-D double-layer quadrature (DDDQ) coil, which can realize the anti-misalignment constant voltage output of the system.Design/methodology/approachFirst, this paper establishes the equivalent circuit of a WPT system based on dual LCC-S compensation topology and analyzes its constant-voltage output characteristics and the relationship between system transmission efficiency and coupling coefficient. 1. Quadruple D (Ahmad et al., 2019) and double-D quadrature pad (DDQP) (Chen et al., 2019) coils have good anti-misalignment in the transverse and longitudinal directions, but the magnetic induction intensity in the center of the coils is weak, making it difficult for the receiving coil to effectively couple to the magnetic field energy. 2. Based on the double-D quadrature (DDQ) structure coil that can eliminate the mutual inductance between coupling coils and cross-coupling, Gong et al. (2022a) proposed a parameter optimized LCC-LC series-parallel hybrid topology circuit, which ensures that the output current fluctuation is controlled within 5% only when the system is misaligned within the 50% range along the X direction, achieving constant current output with anti-misalignment. The magnetic coupling structure’s finite element simulation model is established to analyze the change in magnetic induction intensity and the system’s anti-misalignment characteristics when the coil offsets along the x and y axes. Finally, an experimental prototype is developed to verify the constant voltage output performance and anti-misalignment performance of the system, and the proposed anti-misalignment system is compared with the systems in existing literature, highlighting the advantages of this design.FindingsThe experimental results show that the system can achieve a constant voltage output of 48V under a time-varying load, and the output voltage fluctuates within ±5% of the set value within the range of ±60 mm lateral misalignment and ±72 mm longitudinal misalignment.Originality/valueBased on the dual LCC-S WPT system, the mutual inductance between the same side coils is reduced by adding decoupling coils, and the anti-misalignment characteristics and output power of the system are improved in a certain range. It is aimed at improving the stability of the system output and transmission efficiency.

MR Safety of Inductively Coupled and Conventional Intraoral Coils.

Intraoral coils (IOCs) in magnetic resonance imaging (MRI) significantly improve the signal-to-noise ratio compared with conventional extraoral coils. To assess the safety of IOCs, we propose a 2-step procedure to evaluate radiofrequency-induced heating of IOCs and compare maximum temperature increases in 3 different types of IOCs. The 2-step safety assessment consists of electric field measurements and simulations to identify local hotspots followed by temperature measurements during MRI. With this method, 3 different coil types (inductively coupled IFC, transmit/receive tLoop, and receive-only tLoopRx) were tested at 1.5 T and 3 T for both tuned and detuned coil states. High SAR and regular MRI protocols were applied for 2 coil positions. The measured E field maps display distinct hotspots for all tuned IOCs, which were reduced by at least 40-fold when the IOCs were detuned. Maximum temperature rise was higher when the coils were positioned at the periphery of the phantom with the coil planes parallel to B 0 . When neither active nor passive detuning was applied, maximum temperature increase of ΔT = 1.3/0.5/1.8 K was found for IFC/tLoop/tLoopRx coils. Hotspots detected by E field measurements, and simulations were consistent. In the simulations, the results were different for homogeneous phantoms compared with full anatomical models. The 2-step test procedure is applicable to different coil types. The results indicate that a risk for radiofrequency-induced heating exists for tuned IOCs, so that adequate detuning circuits need to be integrated in the coils to ensure safe operation.

Mutual Inductance Identification and Bilateral Cooperation Control Strategy for MCR-BE System

Considering that the excitation method of an electric excitation synchronous motor has the disadvantages of the brush and slip ring, this article proposes a new brushless excitation system, which includes two parts: a wireless charging system and a motor. To meet the requirements of maximum transmission efficiency and constant voltage output of the system, a bilateral cooperation control strategy is proposed. For the strategy, the buck converter in the receiving side of the system can maintain maximum transmission efficiency through impedance matching, while the inverter in the transmitting side can keep the output voltage constant through phase shift modulation. In the control process, considering that the offset of coupling coils will affect the control results, a grey wolf optimization–particle swarm optimization algorithm is proposed to identify mutual inductance. Simulation and experimental results show that this identification algorithm can improve the identification accuracy and maximize the avoidance of falling into local optima. The final experimental result shows that the bilateral cooperation control strategy can maintain the output voltage around 48 V and the transmission efficiency around 84.5%, which meets the expected requirements.