Resonant Wireless Power Transfer System Research Articles

Synthesis and Control of a Three-Port LCL Resonant Wireless Power Transfer System for DC Energy Conversion Applications

Synthesis and Control of a Three-Port <i>LCL</i> Resonant Wireless Power Transfer System for DC Energy Conversion Applications

A Wearable All-Printed Textile-Based 6.78 MHz 15 W-Output Wireless Power Transfer System and Its Screen-Printed Joule Heater Application

While research in passive flexible circuits for Wireless Power Transfer (WPT) such as coils and resonators continues to advance, limitations in their power handling and low efficiency have hindered the realization of efficient all-printed high-power wearable WPT receivers. Here, we propose a screen-printed textile-based 6.78 MHz resonant inductive WPT system using planar inductors with concealed metal-insulator-metal (MIM) tuning capacitors. A printed voltage doubler rectifier based on Silicon Carbide (SiC) diodes is designed and integrated with the coils, showing a power conversion efficiency of 80-90% for 2-40 W inputs over a wide load range. Compared to prior wearable WPT receivers, it offers an order of magnitude improvement in power handling along with higher efficiency (approaching 60%), while using all-printed passives and a compact rectifier. The coils exhibit a simulated Specific Absorption Rate (SAR) under 0.4 W/kg for 25 W received power, and under 21 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C increase in the coils' temperature for a 15 W DC output. Additional fabric shielding is investigated, reducing harmonics emissions by up to 17 dB. We finally demonstrate a wirelessly-powered textile-based carbon-silver Joule heater, capable of reaching up to 60 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$^{\circ }$</tex-math></inline-formula> C at 2 cm separation from the transmitter, as a wearable application which can only be wireless-powered using the proposed system.

Research on MLD Modeling and Predictive Control of Magnetically Coupled Resonant Bidirectional WPT System

The recent studies on magnetically coupled resonant bidirectional wireless power transfer (MCR-BWPT) systems disregard the challenges posed by nonlinearity, discrete switching action, and hybrid properties within the system. This research focuses on the D-LCL resonant compensation topology MCR-BWPT system. The switch tube’s switching state dictates the division of various working modes and the determination of the switching conditions between them. The coupling relationship between the continuous dynamic characteristics of the system and discrete events and the constrained conditions of the system are derived. The Hybrid System Description Language (HYSDEL) is used to build the Mixed Logic Dynamic (MLD) model of the system. The MLD model is employed as the prediction model, and the hybrid model predictive controller of the MCR-BWPT system is constructed according to the quadratic performance index. Finally, to verify the accuracy of the MLD model and the feasibility of the control strategy, the simulation model of the MLD model is established in MATLAB/Simulink. The study’s findings show that, in terms of response time at system startup and power fluctuation suppression, the approach put forward in this research performs better than both the conventional bilateral dual-phase-shift control strategy and the PQ-based bilateral power control strategy. The MCR-BWPT system can operate more steadily now that PQ’s bidirectional power control technique is in place. The system’s forward and reverse transmission efficiency is increased by 0.29% and 0.32% compared to the conventional bilateral dual-phase-shift control approach; the increases are 0.28% and 0.09%, each compared to the bilateral power control strategy based on PQ.

A MCR‐WPT system based on LCL‐S/P hybrid compensation network with CC/CV and maximum power optimization suiting for battery charging

AbstractA novel magnetic coupling resonance wireless power transfer (MCR‐WPT) system, which has constant‐current (CC) and constant‐voltage (CV) output characteristics suiting for batteries charging, is proposed in this paper. The hybrid compensation topology is adopted; in detail, the LCL‐P circuit topology is used in the CC mode, while the LCL‐S topology is used in the CV mode. Since the switchable components are only located at the receiving side of WPT, the switching can be controlled by the receiving side based on the batteries’ state without data communication between transmitting side and receiving side. Furthermore, an adjustable frequency tuning method which is based on proportion integration (PI) closed‐loop controlled by the transmitting side is applied to maximize the current of the transmitting coil. This method also can solve the frequency splitting problem, improving the stability and power of the system while the distance of the two sides changes. The performance of the proposed WPT system is verified by simulation and experiments. The experiment results show that the load current variation is less than 3% in the CC mode and the load voltage changes less than 5% in the CV mode, as the load resister changes from 5 to 20 Ω.

Importance of Functional Parameters on the Effective Operation of Resonant Multi-receiver Wireless Power Transfer System

Importance of Functional Parameters on the Effective Operation of Resonant Multi-receiver Wireless Power Transfer System

Research on dual‐coupled wireless power transfer system for cardiac pacemaker based on integrated coils

SummaryIn order to reduce the implantation volume and improve the transmission efficiency of the magnetically coupled resonant wireless power transfer system for cardiac pacemakers, a dual‐coupled wireless power transfer system for cardiac pacemakers that integrates a compensation coil into the main coil was designed. First, the mutual inductance equivalent model of the dual‐coupled wireless power transfer system was established and the impedance matching parameters were solved. The double‐sided inductor–capacitor–inductor (DS‐LCL) circuit simulation model considering the equivalent series resistance was established with MATLAB. The influence of different inductance ratios on the output power and transfer efficiency of the system was analyzed in the range of 200–300 kHz, and the system parameters for optimal transfer efficiency were determined. Second, the compensation coil on the same side was naturally decoupled by changing the aspect ratio of the compensation coil. The magnetic field distribution between the internally integrated dual‐coupled structure proposed in this paper and the conventional integrated structure was compared using COMSOL, and the safety assessment of the system was conducted, considering parameters such as temperature rise and specific absorption rate. Finally, an experimental platform was established to verify the system's output performance and safety. The results showed that compared with conventional integrated structures, the proposed integrated structure increased the output power by 0.229 W and transmission efficiency by 10.08% at a transmission distance of 8 mm. The maximum temperature rise is 1.9°C.

Rotation manipulation of high-order PT-symmetry for robust wireless power transfer

Magnetic resonance coupling plays an important role in the non-radiative wireless power transfer without cables. However, the basic near-field coupling also has some key limitations on the resonance wireless power transfer (WPT). On the one hand, when the transfer distance is short, the eigenfrequencies of the WPT system will split because of the strong near-field coupling between the resonance transmitter and receiver. On the other hand, although the working frequency is fixed for the long-distance case, the transfer efficiency will be significantly dropped for the weak coupling strength. Therefore, a long-captivated problem of the resonance WPT systems is that it is difficult to balance the fixed working frequency and high efficiency of the devices. In this work, we put forward the composite transmitter with a pair of resonance coils of different size. By assisting the rotational degrees of freedom in the composite transmitter, a high-order parity-time-symmetric non-Hermitian system can be established. Especially, in contrast to the conventional resonance WPT scheme, the robust WPT can maintain fixed working frequency and efficiency over a varying transfer distance in the optimized WPT system with composite transmitter, since this eigenfrequency is insensitive to the operational conditions. Our findings demonstrate that the composite transmitter possesses better performance for WPT than its single counterpart, offering the opportunities for engineering novel designer electromagnetic transfer states with unique robustness.

Axial magnetic quadrupole mode of dielectric resonator for omnidirectional wireless power transfer

To achieve omnidirectional wireless power transfer (WPT) with high efficiency, a high Q-factor transmitter generating homogeneous magnetic field is crucial. Traditionally, orthogonal coils of different shapes are used to realize transmitters. In this paper, we develop an omnidirectional magnetic resonant WPT system based on a dielectric disk resonator with colossal permittivity and low loss operating at the axial magnetic quadrupole mode. The constant power transfer efficiency of 88% at the frequency of 157 MHz over the transfer distance of 3 cm for all azimuth angles of a receiver is experimentally demonstrated. The possibility of multi-receivers charging is also studied demonstrating a total efficiency of 90% regardless of azimuth angle between two receivers with respect to the transmitting disk resonator. The minimized exposure of biological tissues to the electric and magnetic fields as well as a low specific absorption rate is observed that makes the WPT system safer for charging with higher input power.

Multi-objective ant lion optimization for parameter optimization of wireless power transfer systems

The effective transmission distance of a magnetic coupling resonance (MCR) wireless power transfer (WPT) system is an essential index of wireless power transfer. Existing systems often suffer from short transmission distances, low power, and low efficiency. In this paper, a method is proposed for improving the parameters of wireless power transfer systems to enhance the performance of the systems. The main parameters affecting the output power and transmission efficiency are determined by analyzing the MCR WPT system with SS-type topology. In addition, the multi-objective ant lion optimizer is combined with tent chaotic mapping to generate the location information of the initial population by using the distribution and randomness of tent chaotic mapping, which increases the diversity of the people and improves the convergence speed and global search capability of the algorithm to achieve multi-objective parameter optimization, and the optimized model is also analyzed. Experiments show that the optimized MCR WPT system has improved output power and transmission efficiency at a longer distance. The optimal transmission distance of the system is about 0.2 m with a maximum output power of 129.3 W, and the axial offset stability of the system is enhanced. Finally, the effectiveness of the improved model is verified by building a prototype system. It provides a valuable reference for the research of improving wireless power transfer.

A Design of Magnetic Resonant Wireless Power Transfer System using Flexible Resonator Coils

A Design of Magnetic Resonant Wireless Power Transfer System using Flexible Resonator Coils

Power Injection and Free Resonance Decoupled Wireless Power Transfer System with Double-Switch

This article presents a type of power injection and free resonance decoupled wireless power transfer (WPT) system, the double-switch independent power injection and free resonance wireless power transfer (IPIFR-WPT) system working in CCM. Based on the stroboscopic mapping model, the theoretical results show that the operation point of the proposed WPT system is determined by itself instead of the switching control strategy. Specifically, once the voltage on the primary capacitance does not decrease to the input voltage in the free-resonance process, the diode in series would not turn on and the system would not switch to the power injection process. Therefore, there is a wide soft-switching margin to ensure the system operating in soft-switching states. Another characteristic of the proposed WPT system is the monotonicity between output power and operation cycle, which presents a simple power control method. And since the soft-switching margin may have intersection under dynamic coupling coefficient, the proposed system maintains soft-switching states with a fixed switching strategy and presents advantage to resist the dynamic change of coupling coefficient. All the characteristics of the proposed WPT system mentioned above have been verified in both theory and experiment.

Reconfigurable PCB Coil Array Loaded With PIN Diodes for Improving Transmission Efficiency in MCR-WPT Systems

In this letter, we propose a reconfigurable coil array by loading PIN diodes to solve the problem of transmission efficiency degradation due to lateral misalignment in magnetically coupled resonant wireless power transfer (MCR-WPT) systems. The reconfiguration of the coil array is achieved by changing the capacitance of the coil array through the ON/OFF of the PIN diodes, thus adjusting the magnitude of the induced current and achieving higher transmission efficiency. By specifying one of the four loaded PIN diodes in the transmitting (Tx) coil array as ON state by the relative position of the receiving (Rx) coil to the Tx coil array, a significant improvement in transmission efficiency with a wider area of strong coupling can be obtained compared to a conventional Tx coil array without loading PIN diodes. This can be used in high efficient multi-coil versus single-coil WPT systems to provide more positioning freedom for Rx coil.

A Comparative Performance Analysis of Wireless Power Transfer with Parametric Simulation Approach

This paper presents a parametric optimization and normalization approach for coreless Resonant Inductive Coupling Wireless Power Transfer (RIC-WPT) systems. The used system is based on a series–series (SS) compensated circuit via flat spiral coils. Moreover, the recommended approach system finds optimum capacitor values for the best efficiency point where the RIC-WPT system operates. Flat spiral three-dimensional (3D) coils are modelled and parametric analysed with different air gaps in ANSYS-Electronics-Maxwell software which is based on the Finite Element Method (FEM). Then power electronics circuit with a full-bridge inverter is designed in Ansys/Simplorer software. The coils and the power electronics circuit are co-simulated with parametric values. Thus, as a result of parametric simulation studies, the most efficient version of a Wireless Power Transfer (WPT) system structure is proposed with the design and normalized power electronics elements that can be physically applied for the chosen operating frequency value. As a result of the simulation studies, power transmission is realized with an efficiency of approximately 74.31% while the distance between the coils was 200 mm. Furthermore, useful information for WPT designs is been obtained thanks to co-simulation studies by changing power electronics circuit parameters and electromagnetic modelling parameters.

Level pinning of anti-PT-symmetric circuits for efficient wireless power transfer.

Wireless power transfer (WPT) technology based on magnetic resonance (a basic physical phenomenon) can directly transfer energy from the source to the load without wires and other physical contacts, and has been successfully applied to implantable medical devices, electric vehicles, robotic arms and other fields. However, due to the frequency splitting of near-field coupling, the resonant WPT system has some unique limitations, such as poor transmission stability and low efficiency. Here, we propose anti-resonance with level pinning for high-performance WPT. By introducing the anti-resonance mode into the basic WPT platform, we uncover the competition between dissipative coupling and coherent coupling to achieve novel level pinning, and construct an effective anti-parity-time (anti-PT)-symmetric non-Hermitian system that is superior to previous PT-symmetric WPT schemes. On the one hand, the eigenvalue of the anti-PT-symmetric system at resonance frequency is always pure real in both strong and weak coupling regions, and can be used to overcome the transmission efficiency decrease caused by weak coupling, as brought about by, for example, a large size ratio of the transmitter to receiver, or a long transmission distance. On the other hand, due to the level pinning effect of the two kinds of coupling mechanisms, the working frequency of the system is guaranteed to be locked, so frequency tracking is not required when the position and size of the receiver change. Even if the system deviates from the matching condition, an efficient WPT can be realized, thereby demonstrating the robustness of the level pinning. The experimental results show that when the size ratio of the transmitter coil to the receiver coil is 4.29 (which is in the weak coupling region), the transfer efficiency of the anti-PT-symmetric system is nearly 4.3 (3.2) times higher than that of the PT-symmetric system when the matching conditions are satisfied (deviated). With the miniaturization and integration of devices in mind, a synthetic anti-PT-symmetric system is used to realize a robust WPT. Anti-PT-symmetric WPT technology based on the synthetic dimension not only provides a good research platform for the study of abundant non-Hermitian physics, but also provides a means of going beyond traditional near-field applications with resonance mechanisms, such as resonance imaging, wireless sensing and photonic routing.

High-efficiency bidirectional resonant WPT system for electric vehicles

&lt;p&gt;The wireless power transfer (WPT) system has become popular given its safety and flexibility in electric vehicle (EVs) charging applications. Due to the increasing number of EVs, vehicle to grid (V2G) can be implemented in the future in which a bidirectional WPT is one of the key features. A high-efficiency bidirectional resonant WPT system is studied and implemented in this study. Besides bidirectional capability, single stage and regulated output voltage are other features of this work. It is done by using the variable frequency control without sacrificing efficiency and conforming to the typical frequency range of the WPT system for EVs application. The analysis of the series-series compensated WPT is presented, followed by the design consideration of the developed bidirectional WPT system. At last, the implementation and experimental results for a 3 kW laboratory prototype are also presented to show the validity and the feasibility of the proposed scheme. A 96.8% efficiency at a 210-mm gap and a 95% efficiency at a 250-mm gap can be achieved under a rated power condition.&lt;/p&gt;

A Six-Switch Mode Decoupled Wireless Power Transfer System with Dynamic Parameter Self-Adaption

For the fully resonant wireless power transfer (WPT) system, the high coupling of the converter and the resonant network introduced many problems, such as frequency splitting, the power curve peak limit, and the strict switch strategy. To solve these problems, this paper proposed a new six-switch topology based on the full–-bridge converter. With the unique structures containing two capacitor-isolated switches and a source-isolated diode, the system decouples the converter and the resonant network, and its modes have been decoupled, called the independent power injection and free resonance WPT (IPIFR–WPT) system. The capacitor-isolated switches and the source-isolated diode make the converter operate only when the voltage on the primary capacitor is equal to the source voltage, and the source will be isolated by the diode when the capacitor voltage is great than the source, which provides a wide time margin for the switches of the converter to turn on in advance. In this margin, the operation point is self-determined the same whenever the switches turn on so that the system’s performance is consistent. Based on this characteristic, the system can self-adapt a dynamic change in system parameters, with at least 15% tolerance for the coupling coefficient and 14% for the load resistance.

Numerical Evaluation of Circuit Model for Fast Computational Analysis of Resonant Wireless Power Transfer System

Numerical Evaluation of Circuit Model for Fast Computational Analysis of Resonant Wireless Power Transfer System

Gallium Nitride Power Devices in Magnetically Coupled Resonant Wireless Power Transfer Systems

The main function of power devices is to convert electrical energy through high-speed switching, such as AC/DC, high and low voltage conversion, etc. Therefore, the performance of the device directly affects the performance of the power electronic device, thereby further affecting the conversion efficiency of electrical energy. The arrival of the 5G era has greatly increased the demand for gallium nitride (GaN). The development of the wireless communication market has made GaN play a key role in many aspects of human activities. The main aim of this article is to research the application of GaN power devices in magnetically coupled resonant wireless power transfer (WPT) systems. This paper first introduces the related concepts of GaN power devices, magnetic coupling resonance and WPT, and analyzes the construction of magnetic coupling resonance WPT system in detail. Secondly, the energy transmission structure is analyzed, the system is designed and the system loss is calculated and analyzed. The system loss experiment shows that by using the output capacitor of the GaN device, the dead time is optimized, the conduction loss of the switch tube is reduced, the efficiency of the converter device is improved, and the practical application of the GaN device is provided.

Coupler Loss Analysis of Magnetically Coupled Resonant Wireless Power Transfer System

The demand for electric vehicles has increased over the past few years. Wireless power transfer for electric vehicles provides more flexibility than traditional plug-in charging technology. Charging couplers are critical components in wireless power transfer systems. The thermal effect produced by the magnetic coupler in work will cause the temperature of the device to rise rapidly, affecting the work efficiency, transfer power, operation reliability, and service life. This paper modeled and analyzed each component's temperature distribution characteristics and thermal behavior. Firstly, the magnetic coupler's mutual inductance and magnetic circuit model are established, and the thermal model of the magnetic coupler analyzes the heat generation process. The thermal models of the coupler under three different magnetic core distributions are established, and the temperature rise of each component is obtained. The temperature rise of different parts of the coupler is verified by the temperature rise test structure of the experiment.

An Adaptive Control Strategy for Underwater Wireless Charging System Output Power with an Arc-Shaped Magnetic Core Structure

Aiming at the problem of unstable output power of wireless charging systems for autonomous underwater vehicles (AUVs), a magnetic coupler (MC) with an arc-shaped core structure is introduced and an output power stabilization control strategy based on mutual inductance identification algorithm is proposed. Firstly, an arc-shaped MC with high tolerances, excellent magnetic coupling and weak electromagnetic interference (EMI) is designed for the cylinder-shaped AUV. Based on ANSYS Maxwell simulation, an analysis of the magnetic field and comparative misalignment tests are carried out for the arc-shaped and the double dipole core structures. Secondly, a mathematical model of the LCC-S type magnetically coupled resonant wireless power transfer (MCR-WPT) system is developed, and a particle swarm parameter identification algorithm with adaptive inertia weights is proposed. Finally, the output power is steadily controlled by real-time adaptation of the duty cycle for the Buck-Boost circuit. The results show there is a maximum error within 2.5% in mutual inductance identification when the load is changed from 0 Ω to 12 Ω and the mutual inductance is changed from 25 μH to 50 μH. The system output power is steady at around 680 W with a maximum fluctuation rate of 4.90%, which verifies the efficiency of the power stabilization control strategy.