Magnetic Coupling Resonant Wireless Power Research Articles

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.

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 Review of Metamaterials in Wireless Power Transfer.

Wireless power transfer (WPT) is a technology that enables energy transmission without physical contact, utilizing magnetic and electric fields as soft media. While WPT has numerous applications, the increasing power transfer distance often results in a decrease in transmission efficiency, as well as the urgent need for addressing safety concerns. Metamaterials offer a promising way for improving efficiency and reducing the flux density in WPT systems. This paper provides an overview of the current status and technical challenges of metamaterial-based WPT systems. The basic principles of magnetic coupling resonant wireless power transfer (MCR-WPT) are presented, followed by a detailed description of the metamaterial design theory and its application in WPT. The paper then reviews the metamaterial-based wireless energy transmission system from three perspectives: transmission efficiency, misalignment tolerance, and electromagnetic shielding. Finally, the paper summarizes the development trends and technical challenges of metamaterial-based WPT systems.

Analysis of transmission performance on wireless power transfer system with metamaterial

Abstract In order to solve the problems of low power transfer efficiency (PTE) and limited distance in magnetic coupling resonant wireless power transfer (MCR-WPT) technology. In this paper, based on the magnetic field control ability of metamaterials (MMs), the way to improve the performance of MCR-WPT systems is studied. First, the influence of MMs on the coupling of MCR-WPT system is theoretically analyzed by establishing an equivalent circuit model. Through a series of simulations and experiments, the relationships between the PTE and the array and placement of the MM slab are investigated. The results demonstrate that when one MM slab is placed in the middle, near the Tx coil or the Rx coil, the optimal PTE can be obtained by inserting one slab with $6 \times 6$ , $1 \times 1$ , and $6 \times 6$ arrays, respectively. Moreover, the systems with multilayer MM slabs are also studied. The measured PTEs on one, two, and three layers of MM slabs can increase by 20.6%, 29.3%, and 22.6%, respectively. The efficiency improvement capability of one MM slab is better than three slabs but worse than two slabs. This paper discusses the application of MMs in MCR-WPT systems, which has a certain reference significance.

A secured wireless charging scheme with data transmission

This research task proposes a magnetic resonant coupling wireless power transfer(MRC-WPT) scheme for electric vehicles, which realizes secure data communication between the wireless charging station and the electric vehicle using binary phase shift-keying (BPSK) data transmission, thereby waving any radio frequency(RF) communication links. The secondary side is designed to accept power, while it transmits data back to the primary side simultaneously. The BPSK design ensures data transmission robustness to against disturbance interference. The data are encrypted by the user's biometric features for information security. The magnetic resonance performs better than that of the traditional magnetic induction in the power transmission efficiency against coil misalignments. With the Internet of Thing(IOT) architecture, the encrypted data can be stored and retrieved via the cloud server.

Analysis of four-coil magnetic resonance coupling wireless power transfer system based on LCC-SSS compensation network

The classical four-coil magnetic resonance coupling wireless power transfer (MRC-WPT) system usually uses a Series-Series-Series-Series (SSSS) compensation network, while its input series resistance and load resistance are designed approximately. I It is a remarkable fact that the power loss of the input series resistance adversely affects the overall efficiency of the WPT system, but the absence of the resistance will lead to the input current surge when the four-coil system is detuned, which is not conducive to the stability of the security of the circuit system. With this aim in mind, an Inductance-Capacitance-Capacitance-Series-Series-Series (LCC-SSS) compensation network is proposed in this paper, which removes the input series resistance to improve the total efficiency on the premise of ensuring the reliability of the system. Relation between transmission efficiency, transmission power and parameters of LCC-SSS compensation network, the parametric calculation method of LCC compensation network is presented. Finally, the experimental results compare the transmission power and efficiency of the two compensation networks and verify the correctness of the LCC-SSS compensation network.

Communication-Less Receiver-Side Resonant Frequency Tuning for Magnetically Coupled Wireless Power Transfer Systems

Compensating for deviations in the resonant frequency is crucial in magnetic resonance coupling wireless power transfer (WPT) systems. Thus, this study proposes a communication-less receiver-side resonant frequency-tuning scheme that compensates for the reactance in the receiver without communicating with the transmitter. The proposed scheme comprises an inductor-capacitor-capacitor compensation topology at the transmitter and a half-bridge circuit at the receiver, whose operating phase is set to be orthogonal to the receiver current. Resonant frequency tuning can be achieved by adjusting the DC voltage applied to the half-bridge circuit to maximize the power received at the load. The reactance compensation ability of the proposed scheme is analyzed through experiments on a 200 kHz WPT system. When the secondary capacitance deviated from –20% to +20%, the efficiency degradation was maintained within 6.7% with the proposed scheme, whereas the efficiency degraded by up to 33.3% without compensation.

5G Magnetic Resonance Coupling Planar Spiral Coil Wireless Power Transfer

Wireless Power Transfer in the 5G frequency band is the most promising technology to power up ubiquitous small electronic devices as well as IoT devices. A strongly coupled magnetic resonance WPT technique that focuses on near-field electromagnetic energy has been proposed in this paper. However, most Magnetic Resonance Coupling Wireless Power Transfer (MRC WPT) applications have been designed in kHz and MHz frequency spectrum. This paper demonstrates Planar Spiral Coil Magnetic Resonance Coupling (PSC MRC) WPT designs at 5G (GHz) frequencies. Also, the transformation technique of the low frequency (kHz and MHz) magnetic resonance circuit model equations to high frequency (GHz) circuit model equations to achieve a high-efficiency power transfer. PSC MRC WPT designs structure antennas are designed at 3.4 - 3.5 GHz in the form of circular and square shapes with 1 turn coil. The proposed antenna structures are firstly being optimized in a full-wave electromagnetic simulator, CST Microwave Studio to resonate at the 3.4 - 3.5 GHz band. Then, the close-loop equations to determine the efficiency of 5G Magnetic Resonance Coupling Planar Spiral Coil Wireless Power Transfer is designed. Lastly, the results are compared with the simulation and calculated parts. The highest efficiency of the PSC MRC circular antenna is 31.58 % when the distance is at 2 mm, and 31.26 and 31.02 % when the distance is at 3 and 4 mm, respectively. The efficiency of circular PSC MRC is found to be 25 % better than the efficiency of square shape design. HIGHLIGHTS IoT devices need to be charged and maintained as the network system has massive numbers of sensors. Wireless power transfer is a promising technology to power up IoT devices This paper proposed, a WPT technique based on strongly coupled magnetic resonance which focuses on the near-field electromagnetic energy. This technique can extend the distance of the power transfer between the transmitter and the receiver The transformation technique of the low frequency (kHz and MHz) magnetic resonance circuit model equations to high frequency (GHz) circuit model equations to achieve a high-efficiency PSC MRC WPT design structure is introduced in this paper This novel technique can be applied to effectively design PSC MRC Antenna WPT for 5G applications. Most reported Magnetic Resonance Coupling Wireless Power Transfer (MRC WPT) applications have been designed in kHz and MHz frequency spectrum GRAPHICAL ABSTRACT

A Linear-Power-Regulated Wireless Power Transfer Method for Decreasing the Heat Dissipation of Fully Implantable Microsystems.

Magnetic coupling resonance wireless power transfer can efficiently provide energy to intracranial implants under safety constraints, and is the main way to power fully implantable brain-computer interface systems. However, the existing maximum efficiency tracking wireless power transfer system is aimed at optimizing the overall system efficiency, but the efficiency of the secondary side is not optimized. Moreover, the parameters of the transmitter and the receiver change nonlinearly in the power control process, and the efficiency tracking mainly depends on wireless communication. The heat dissipation caused by the unoptimized receiver efficiency and the wireless communication delay in power control will inevitably affect neural activity and even cause damage, thus affecting the results of neuroscience research. Here, a linear-power-regulated wireless power transfer method is proposed to realize the linear change of the received power regulation and optimize the receiver efficiency, and a miniaturized linear-power-regulated wireless power transfer system is developed. With the received power control, the efficiency of the receiver is increased to more than 80%, which can significantly reduce the heating of fully implantable microsystems. The linear change of the received power regulation makes the reflected impedance in the transmitter change linearly, which will help to reduce the dependence on wireless communication and improve biological safety in received power control applications.

Extensible Low-Profile Coplanar Wireless Power Transfer System for Multiload Applications With Load-Independence Constant Current Output

This article proposes a low-profile coplanar magnetic coupling resonance wireless power transfer system, which can be expanded segment by segment to power more receivers over a long distance with load-independent constant current output. Due to the low structural profile, it can easily conform to the environment such as desktops, floors, and walls, occupying a small space. By placing low-profile ferrite plates on or under the junctions of adjacent coplanar coils, the main coupling coefficients of the adjacent coils are significantly enhanced, and therefore, the power transmission efficiency (PTE) of the system is greatly improved. With the fixed operating frequency, load-independent current characteristics, simple structure, coplanarity with the environment, good scalability, and high PTE, the system can be easily utilized in various medium and long-range multiload WPT applications. The article describes its principle in detail and clarifies the influence of losses on system performance such as output current characteristics, PTE, and the maximum number of the charging segments. The experimental platform with two and three receivers was established to verify the theory, and the measurement results are in good agreement with the theoretical analysis. The maximum measured PTE reached 93.8% and 93.6% for two and three receivers, respectively.

Modern Advances in Magnetic Materials of Wireless Power Transfer Systems: A Review and New Perspectives.

The magnetic coupling resonant wireless power transfer (MCR-WPT) system is considered to be the most promising wireless power transfer (WPT) method because of its considerable transmission power, high transmission efficiency, and acceptable transmission distance. For achieving magnetic concentration, magnetic cores made of magnetic materials are usually added to MCR-WPT systems to enhance the coupling performance. However, with the rapid progress of WPT technology, the traditional magnetic materials gradually become the bottleneck that restricts the system power density enhancement. In order to meet the electromagnetic characteristics requirements of WPT systems, high-performance Mn-Zn and Ni-Zn ferrites, amorphous, nanocrystalline, and metamaterials have been developed rapidly in recent years. This paper introduces an extensive review of the magnetic materials of WPT systems, concluding with the state-of-the-art WPT technology and the development and application of high-performance magnetic materials. In addition, this study offers an exclusive reference to researchers and engineers who are interested in learning about the technology and highlights critical issues to be addressed. Finally, the potential challenges and opportunities of WPT magnetic materials are presented, and the future development directions of the technology are foreseen and discussed.

Enhancement of robustness to frequency detuning with wireless power transfer based on Van der Pol resonance

AbstractIn near‐field energy transmission, wireless power transfer based on magnetic coupling resonance is preferred. For efficient power transfer, the quality factor of magnetic coupling resonance wireless power transfer (MCR‐WPT) system should be kept at a high value, which makes the system sensitive to frequency detuning. Different from conventional approaches dealing with the problem in linear MCR‐WPT system, this paper proposes a novel MCR‐WPT system, which is based on Van der Pol nonlinear resonant circuit to address the problem of frequency detuning. A nonlinear resistor is introduced, and the nonlinear Van der Pol MCR‐WPT system is established. Based on the mathematical model and the theoretical analysis, it is found that the frequency band is broadened. To validate the performance of the proposed system, extensive simulation and experimental work are conducted. Unlike the traditional linear system, which only peaks at the resonant frequency, the results show that the output of the proposed system is still high within a certain frequency band when the operating frequency deviates from the original resonant frequency. The impact of frequency detuning caused by variation of capacitance is also studied. It can be concluded that the proposed MCR‐WPT system is effective in coping with the frequency detuning.

Structure Design of Quadrilateral Overlapped Wireless Power Transmission Coupling Coil

The application of wireless power transmission technology is becoming more and more extensive. However, in practical applications, the problem of reducing the energy transmission efficiency caused by the offset of the coupling coil needs to be solved urgently. Changing the coil structure is a widely adopted method to deal with this problem. Based on the characteristics of the existing magnetic coupling resonant wireless power transmission system and the principle of the anti-offset coil, this paper innovatively designs a new type of quadrilateral overlapping wireless power transfer coupling coil, which has a strong anti-offset capability. The new type of coil model was built in the simulation and experiment, and the relevant parameters were measured. Experimental results verify that the proposed coil structure has an excellent anti-offset capability.

Analysis and Design of Wireless Power Transfer System for Rotational Inertial Navigation Application

Cables or slip-rings are often used to power loads on a rotating unit in the rotation modulated inertial navigation system (RMINS). However, these power supply methods have the disadvantages of cable winding and slip ring friction and wear, which reduces the reliability and life of the RMINS. Therefore, this paper applies magnetic coupling resonant wireless power transfer (MCRWPT) technology to the RMINS to avoid the shortcomings of the above power supply methods. Furthermore, according to the structure and working characteristics of the RMINS, a simple design method of the MCRWPT system without any feedback control is proposed. Based on the ANSYS simulation, the magnetic shielding structure is designed to reduce magnetic leakage, and the efficiency of the MCRWPT system is optimized by designing the excitation frequency. Experiments verify the effectiveness of the proposed method. The experimental results show that the designed MCRWPT system can achieve an efficiency of 74.6% with an output power of 10 W and has been successfully applied to the uniaxial rotation module inertial navigation system. Finally, the design method of the MCRWPT system is simple, and it has guiding significance for the design of the wireless power transfer system in the RMINS.

Matching network design for input impedance optimization of four-coil magnetic resonance coupling wireless power transfer systems

Matching network design for input impedance optimization of four-coil magnetic resonance coupling wireless power transfer systems

Analysis of Symmetric Two and Four-coil Magnetic Resonant Coupling Wireless Power Transfer

This study examined the efficiency of power transfer for two-coil and four-coil spiral magnetic resonant coupling wireless power transfer (WPT) using distance to coil diameter (D/dm) ratio and reflection coefficient, S21 value. Adding resonators reduced the total resistance in the two-coil WPT system while increasing the S21 values of the whole system. A same-size spiral coil was proposed for the system and simulated using computer simulation technology (CST). A prototype with similar specifications for a four-coil design was implemented for verification. The proposed method yielded an optimal efficiency of 76.3% in the four-coil system, while the two-coil WPT yielded a 23.2% efficiency with a 1.33 D/dm ratio.

Magnetic resonance coupling wireless power transfer for green technologies

Wireless <span>power transfer (WPT) is a technology that is considered the focus of scientists' attention for its development and creation to be compatible with many devices that are used today and also consider one of the green technology apps which means any technology can reduce the effect of people on the environment which is today grow continuously. In this paper, a wireless power transfer for a mobile charger had been discussed to get a maximum power and efficiency power transfer. WPT is considered as a reliable technology, efficient, fast, not using wires, and can be used for short and long-range. There are three methods for WPT, electromagnetic induction, magnetic resonance coupling, and radio waves which are classified by the distance that sends the power. Magnetic resonance coupling is the method that has been focused on in this paper because of compatibility with short or medium distances as battery chargers which depend on the magnetic field to transfer power without wires that can protect devices from damages and heating. As result the effect of distance on efficiency has been discussed with reached to nearer distance can improve efficiency however by using magnetic resonance technique, acceptable efficiency can be obtained with appropriate distance.</span>

Wireless power transfer system with enhanced efficiency by using frequency reconfigurable metamaterial

The wireless power transfer (WPT) system has been widely used in various fields such as household appliances, electric vehicle charging and sensor applications. A frequency reconfigurable magnetic resonant coupling wireless power transfer (MRCWPT) system with dynamically enhanced efficiency by using the frequency reconfigurable metamaterial is proposed in this paper. The reconfigurability is achieved by adjusting the capacitance value of the adjustable capacitor connected in the coil of the system. Finite element simulation results have shown that the frequency reconfigurable electromagnetic metamaterial can manipulate the direction of the electromagnetic field of the system due to its abnormal effective permeability. The ultra-thin frequency reconfigurable metamaterial is designed at different working frequencies of 14.1 MHz, 15 MHz, 16.2 MHz, 17.5 MHz, 19.3 MHz, 21.7 MHz and 25 MHz to enhance the magnetic field and power transfer efficiency (PTE) of the system. Frequency reconfigurable mechanism of the system with the frequency reconfigurable metamaterial is derived by the equivalent circuit theory. Finally, further measurement which verifies the simulation by reasonable agreement is carried out. PTE of the system by adding the metamaterial are 59%, 73%, 67%, 66%, 65%, 60% and 58% at different working frequencies. PTE of the system with and without the metamaterial is 72% and 49% at the distance of 120 mm and the frequency of 15 MHz, respectively.

Wireless power transfer system based on frequency and impedance matching hybrid adjustment against system detuning

System detuning caused by a variation in the distance between the transmitting and receiving terminals can greatly reduce the transmission power and efficiency of a magnetic resonance-coupled wireless power transmission (WPT) system, which limits the WPT application scope. This paper proposes a magnetic resonance coupling wireless power transmission system, which is based on jointly and continuously adjustable frequency compensation (CAFC) and two-transistor-controlled variable capacitor circuits (TCVCs). Therefore, this system can reach the resonant state by using CAFC and two-TCVCs when the transmission distance is changed. The proposed system can adaptively adjust combinations of the operating frequency and equivalent compensation capacitor’s capacitance to achieve impedance matching avoiding the phase difference caused by the imaginary part of the impedance, thus maintaining stable transmission efficiency under the condition of transmission distance variation. Compared to the traditional magnetic coupled resonant circuit based on impedance matching or variable resonant frequency, the proposed system achieves higher efficiency and stability and dynamic distance adaptation.

Multifrequency and Multiload MCR-WPT System Using Hybrid Modulation Waves SPWM Control Method

To satisfy independent and controllable power supply requirements for loads with different frequencies and power levels, a multifrequency and multiload (MFML) magnetic coupling resonant wireless power transfer (MCR-WPT) system using hybrid modulation waves sinusoidal pulsewidth modulation (HMW-SPWM) control method is proposed in this article. Based on SPWM, loading a hybrid modulation wave formed by superimposing multifrequency modulation waves to drive the inverter, so the multifrequency hybrid current on the primary side can be obtained. According to the principle of mutual inductance coupling, inductive power with different frequencies is obtained and then separated by multiresonant networks on the secondary side for loads with different frequencies. First, the structure and working principle of a MFML MCR-WPT system controlled by HMW-SPWM are introduced. Then, taking a dual-frequency and dual-load MCR-WPT system as an example, the system is mathematically modeled. Besides, parameters design criteria for reducing interfrequency interference is studied. After that, load characteristics and power factor are analyzed to select appropriate parameters. Furthermore, dynamic characteristics are analyzed. Finally, theoretical results are validated by experiments. The experimental results show that the MFML MCR-WPT system controlled by HMW-SPWM realizes independent and controllable wireless power supply for loads with different frequencies and power levels.