Wireless Power Charging Research Articles

Analysis of Typical Principles and Popularisation Measures of Wireless Charging for Electric Vehicles

Currently, the tram and tanker markets are competing fiercely, and whether wireless charging for electric vehicles can be successfully promoted in the future depends largely on whether the tram market can gain an advantage. Wireless charging has developed to the point where the overall system is not too perfect, so optimising the power system and developing more efficient and safer wireless charging methods is necessary. This paper introduces the basic principles of wireless energy transmission technology and some of the wireless charging methods. The two wireless charging methods of microwave electric power wireless charging and magnetic coupling resonant wireless charging are introduced in principle and the advantages and disadvantages are compared. The safety of wireless charging is maintained, and today's lifestyle is analysed to provide different charging methods for different people. The paper also gives the corresponding measures for the various kinds of dangerous situations that may occur. Finally, the paper gives an outlook and conclusion for the future of wireless charging.

The power control and efficiency optimization strategy of dynamic wireless charging system for multiple electric vehicles

PurposeThis study aims to solve the problem that both the speed and the required driving power of electric vehicles (EVs) will change during the dynamic wireless charging (DWC) process, making it difficult to charge EVs with a constant power considering the overall efficiency of DWC system, the numbers of EVs and the power supply capacity. Therefore, this paper proposes the power control and efficiency optimization strategies for multiple EVs.Design/methodology/approachThe wireless power charging system for multiple loads with a structure of double-sided LCC compensation topology is established. The expressions of optimal transmission efficiency and optimal equivalent impedance are derived. Taking the Tesla Model 3 as an example, a method to determine the number of EVs allowed by one transmitter coil and the overall charging power is proposed considering EV speed, power supply capacity, safe braking distance and overall efficiency. Then, the power control strategy, which can adapt to the changes of EV speed and the efficiency optimization strategy under different numbers of EVs are proposed.FindingsIn this paper, a method to determine the numbers of EVs allowed by one transmitter coil and the overall charging power is proposed considering EVs speed, power supply capacity, safe braking distance and overall efficiency. The accuracy of the charging power is good enough and the overall efficiency reaches a maximum of 91.79% when the load resistance changes from 5Ω to 20Ω.Originality/valueIn this paper, the power control and efficiency optimization strategy of DWC system for multiple EVs are proposed. Specifically, a method of designing the number of EVs and charging power allowed by one transmitter coil considering the factors of EV speed, power supply capacity, safe braking distance and overall efficiency is designed. The overall efficiency of the experiment reaches a maximum of 91.79% after adopting the optimization strategy.

Oblong-shaped piezoelectric ultrasound energy harvester for high-performance wireless power charging

Wireless power charging for implantable biomedical electronics (IBEs) can potentially eliminate the need for frequent battery-replacement surgeries, ultimately improving patients’ quality of life. Ultrasound wireless power transfer (US-WPT) based on piezoelectric receivers has demonstrated significant potential, particularly for deep-seated IBEs. However, most studies on US-WPT have overlooked the optimization of piezoelectric receiver dimensions relative to transmitted ultrasound beam profiles for maximizing battery-charging efficiency for IBEs. This study revealed that a piezoelectric receiver should have dimensions corresponding to the main lobe width of the transmit beam profile within a focal area. Moreover, its output power should be proportional to the cube of the receiver area. Considering these findings, an oblong-shaped ultrasound transmitter and receiver (OsUTR) was developed for efficient WPT, capable of fully charging commercial batteries. In water, the OsUTR produced an output power per unit area of 246.93 mW/cm2, which is 6.588 times higher than that achieved by previously reported methods. This resulted in an average charging rate of 1.64 mC/s, enabling the fully charging of a 30 mAh commercial battery in 1.33 h. Experiments with a 50 mm thick porcine tissue demonstrated that the OsUTR provided an output voltage and current of 38.4 Vp-p and 103.4 mAp-p, respectively. Consequently, full charging of the battery was successfully achieved in 1.80 h. This high-performance OsUTR can enable long-term use of IBEs. This innovation reduces the burden of battery replacement and expands the applicability of implantable devices, driving significant advancements in the IBEs industry.

A Wireless Power Transfer Mattress Based System for Perpetually Operating Physiological Monitoring Wearables.

This article presents a novel wireless power mattress-based system architecture tailored to guarantee continuous energy for in-home environment healthcare wearables intended to be used in the context of patients who would benefit from long-term monitoring of specific physiological biomarkers. The design demonstrates that it is possible to transfer over 20 mW at a primary-secondary distance of 20.7 cm, whilst still keeping within all FCC/ICNIRP safety regulations, using the proposed simplified beamforming-controlled power transfer multi-input single-output system. Compared with other beamforming-controlled based works, the proposed design used non-coupling coil arrays, significantly reducing the algorithmic complexity. An on-chip wireless power charger system was also designed to provide high-efficiency power storage (89.3% power conversion efficiency and 83.9% power charge efficiency), guaranteeing wearables can continuously maintain their functionality. In contrast with conventional NiMh chargers, this work proposes a trimming function that makes it compatible with batteries of varying capacities. It also employs a four-stage charge loop to ensure safety and sustainability during the charging process. Overall, this work shows that by relying on wireless power transfer, it is, in principle, possible to create a safe wearable that could enable continuous monitoring of certain healthcare biomarkers with little or zero maintenance burden for the patients or carers.

Stochastic Resource Optimization for Wireless Powered Hybrid Coded Edge Computing Networks

With the ubiquitous sensing enabled by the Internet-of-Things (IoT), massive amount of data is generated every second, transforming the way we interact with the world. To manage big data and enable analytics at the edge of the network, large amount of computation power is required to perform the computation intensive tasks. However, the energy-constrained IoT devices are not able to perform the computation tasks without compromising the quality-of-service of the applications. In this paper, we propose a hybrid network in which users can fully offload their computation tasks to edge servers through coded edge offloading or perform local computation with the wireless power transfer derived from coalitions of unmanned aerial vehicles (UAVs) serving as mobile charging stations. To minimize the cost of the network, we consider a two-level optimization approach. At the lower level, an optimal UAV coalition that minimizes the network cost is formed. At the upper level, the computation approach for each user is decided while taking into account the stochastic nature of wireless charging efficiency. Given the interrelation between the two levels, we adopt the backward induction optimization strategy to jointly derive the optimal coalition structure and computation approach for each user. In the performance evaluation, we provide extensive sensitivity analyses to study the performance of the cost minimization approaches amid varying network parameters. Moreover, we show that our approach outperforms deterministic optimization approaches in network cost minimization.

Development and Optimization of a Wireless Power Charging System for an Inspection Drone

Unmanned aerial vehicles (UAVs) have advanced and are now employed in a variety of industries, including aerial photography, the military, and transportation. Due to its low battery life, charging it can be difficult. A good UAV solution has been thought of as wireless charging. In this research, we suggested an inductively coupled wireless power transmission system (WPT) and examined the inductive coupling’s power efficiency. A portable energy receiving device positioned on the base of the UAV and a charging station with an induction coil array were both included in the WPT. Additionally, the WPT equivalent circuit was used to examine power efficiency, and a prototype model of the battery coupled with a quadcopter for testing power efficiency was developed. The results onboard the charging circuit design contributed with polarity modulation and safety charging the battery pack, with very light components that considerably decrease the size and weight as much as possible. The charging power conversion efficiency has achieved 83.76% at the maximum.

Planar spiral coil with characteristic analysis and multi-dimensional optimization for wireless power charging system

Planar spiral coil with characteristic analysis and multi-dimensional optimization for wireless power charging system

UAV-Assisted Wireless Charging Incentive Mechanism Design Based on Contract Theory

In wireless sensor networks, terminal devices with restricted cost and size have limited battery life. Meanwhile, these energy-constrained devices are not easy to access, especially when the terminal devices are located in severe environments. To recharge the energy-constrained devices and extend their network service time, unmanned aerial vehicles (UAVs) equipped with wireless power chargers are leased by the third-party control center. To incent the participation of UAVs with different charging capabilities and ensure the strategy-proofness of the incentive mechanism, a hidden information based contract theory model, specifically adverse selection, is introduced. By leveraging individual rationality and incentive compatibility, a contract theory based optimization problem is then formulated. After reducing redundant constraints, the optimal contract items are derived by Lagrangian multiplier. Finally, numerical simulation results are implemented to compare the prepared algorithm with three other baselines, which validates the effectiveness of our proposed incentive mechanism.

Design Considerations with Different Shielding Barriers and HTS Resonance Coils for Wireless Power Charging Unit in High-Speed Magnetic Levitation Train

Design Considerations with Different Shielding Barriers and HTS Resonance Coils for Wireless Power Charging Unit in High-Speed Magnetic Levitation Train

Operating Characteristics of Wireless Multi-Charging Module Based On Multi-Magnetic Resonance Couplings for High Speed Superconducting MAGLEV Train

The various wireless power charging (WPC) units for high speed train such as superconducting magnetic levitation (MAGLEV) and hyperloop train should be practically required to supply electric power without overhead wire power lines of pantographs, since such a unit can reduce the construction cost for pantographs, which charge electric power for superconducting levitation and electric devices inside of traveling train. The wireless charging technology via magnetic resonance method can be able to enable the wireless charging for multiple charging using multiple resonance frequencies from watts or more even meter-level distance. The interference effect for multi resonance frequencies among multi resonance coils should be investigated to design the structure of optimized coupled coils and keep stability. In this paper, authors investigated the intensity and distribution of electric and magnetic fields, as well as thermal distributions for multi magnetic resonant couplings (MRC-WPC) system with multi-resonance frequencies under magnetic shielding structure. In order to examine the interference effects by multi-electromagnetic propagations, charging characteristics for the multi-resonance coupling structure including HTS resonance coil were measured using 100, 370 and 750 kHz power sources.

초고속 자기부상열차용 다중 무선충전장치에서 차폐 장벽조건에 따른 동작특성 조사

We have developed a wireless power charging(WPC) unit for the high-speed superconducting magnetic levitation train to improve the transfer efficiency and stability given that the WPC system can supply electric power without overhead wire power lines of pantographs. Various multi charging units have been required in the super high-speed transportation systems given that their utilization can improve the charging capability and reduce the construction cost of pantographs. Practically, the antenna (Tx) is installed adjacent to the shielding barriers. This way affects the transferred power considering that the Tx and multi-receiver (Rx) coils are intrinsically sensitive to impedance variation due to the external shielding barriers. Thus, the investigations of electric field (E) and magnetic field (B) between Tx and Rx coils should be conducted to control the charging rates. In this study, the authors present the intensities of electric and magnetic fields, as well as the thermal distributions and transfer efficiency between Tx and Rx coils using an RF generator of 370 kHz and 250 W.

Intracranial EEG Recordings of High-Frequency Activity From a Wireless Implantable BMI Device in Awake Nonhuman Primates.

Wireless implantable brain machine interfaces (BMIs) are a promising tool to restore communication and motor functions for individuals with severe motor disability. Prior to clinical application, recording performance must be sufficiently confirmed by animal experiments. In this paper, we aimed to evaluate the performance of a novel BMI wireless device for recording brain activity in two nonhuman primates. We customized a wireless device for implantable BMIs for clinical application. We used a battery instead of a wireless power charging system. Thirty-two electrodes were subdurally implanted over the left temporoparietal cortex. We evaluated the recording performance of the wireless device by auditory steady-state responses (ASSRs) and ketamine-induced responses. The devices successfully recorded broadband oscillatory activities up to the high-frequency band from the temporal cortex in two awake macaque monkeys. Spectral analysis of raw signals demonstrated that the devices detected characteristic results of a 40-Hz ASSR and prominent high-frequency band activity induced by ketamine injection. We confirmed the functionality of the wireless device in recording and transmitting electrocorticography (ECoG) signals with both millisecond precision and recording stability. These results provide confidence that this wireless device can be a translational tool for other fundamental neuroscientific studies in free-moving models.

Three-Mode Variable-Frequency ZVS Modulation for Four-Switch Buck+Boost Converters With Ultra-High Efficiency

This article introduces a three-mode variable-frequency zero-voltage switching (ZVS) modulation method for the four-switch buck+boost converter. This method makes this circuit concept well suited for applications, such as wireless power charging of electric vehicles, where this circuit operates as a power buffer between the resonant converter and the battery with the function to implement the required charging profile. Herein, the buck+boost converter operation is subdivided into three operating regions according to the converter static voltage gain, i.e., buck-, buck-boost- and boost-type modes. A ZVS turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> triangular current mode (TCM) control is adopted for buck-type and boost-type modes. In the buck-boost-type mode when the input-to-output voltage gain is close to unit, all the possible modulation cases are studied thoroughly based on the phase shift of the two half bridges in a full switching period. The selection of the most suitable modulation scheme is performed to minimize the rms value of the inductor current while taking into account the simplification of the practical implementation. Closed-form equations are derived, which makes it easy to implement in practice. The proposed strategy is described, analyzed, and finally verified through a 3 kW surface mounted device (SMD) silicon carbide (SiC) <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> -based laboratory prototype with designed input voltage of 300–600 V and the typical output voltage of 400 V class battery. The efficiency from the measured results is remarkably high, i.e., between 99.2% and 99.6% in a power range from 1 to 3 kW. Finally, tests for the operating mode transitions demonstrated the feasibility of the proposed modulation method. The power density of this converter is 4.86 kW/L.

Comparison of Series/Series and Parallel/Series Resonance Circuit in 1.5 kW Inductive Wireless Power Transfer for EV Applications

Wireless power transfer system plays a key role in the present and future days, because of their upgraded comfort and safety and their merits of less green-house gas (GHG) emissions, cell phones, laptops and electric vehicle charging. In this paper, the basic two resonance circuits were analyzed using an inductive wireless power transfer (IWPT) system, at 1.5 kW, 120-mm, and 85 kHz resonance frequencies. It includes analyzing, designing, and comparing this resonance circuit to choose a suitable resonant circuit for the particular application of an IWPT system. The main analysis and comparison were: Mutual Inductance Effect (Misalignment), stresses on the components, Effect of mutual inductance on the efficiency, Effect of distance on the efficiency, Effect of frequency on the efficiency, Effect of the coupling coefficient (k) on the efficiency and transferred power, Effect of coupling coefficient (k) on the input impedance, Effect of distance on the coupling coefficient (k) and Mutual inductance, and both S/S and P/S circuits have same battery output dc power, current, voltage levels. Both resonance circuits designing formulas derived, electrical parameters are calculated for the given wireless power charger level reaches SAEJ2954 standards. In the end, both resonance circuits are verified through MATLAB simulation of the equivalent circuits.

Effect and Influence of Double Resonance Couplings With Dual Resonance Frequencies for Wireless Power Multi-Charging Module in Superconducting MAGLEV Train

The wireless power charging (WPC) system based on the resonance coupling method, which is composed of separate coils with same resonance frequency, is feasible for exchanging electric energy within 2 m. We have been developed the WPC unit for high speed superconducting magnetic levitation (MAGLEV) train to improve the transfer efficiency and stability since the WPC system can supply electric power without overhead wire power lines of pantographs. Practically, the various WPC units have been required in the super high speed transportation systems since it can reduce the construction cost of pantographs as well as multi charging units to inside and outside of traveling train. From this point of view, authors proposed the enhanced WPC system using multi antenna (Tx) coils with dual-resonance frequencies to expand the practical way. As the multi Tx and multi-receiver (Rx) coils of WPC unit are intrinsically sensitive to impedance variation from external factors such as double resonance coupling coils and the electromagnetic propagations, the effect and influence of charging characteristics for double resonance coupling coils with dual-resonance frequencies should be exanimated. In this paper, the effect and influence of charging characteristics and thermal distributions were investigated under the different resonance coupling modeling with 370 and 750 kHz power sources. In addition, the effect of reflected power at Tx coils was investigated under double resonance coupling coils.

Wireless Power charging system with Self-Adjusting Charge nodes for Electric Vehicles

Electrical Vehicles wireless charging emerges every year with new trends. Charging Techniques for Electric Vehicles has progressed competently in the wireless charging market. Wireless charging takes upon two coupled coils and its mutual inductance is relative to each other. In this work, a self-aligning Wireless Electric Vehicle Charging is proposed. The major idea is to upgrade the efficiency of Electric Vehicle charging through proper alignment for the Receiver and Transmitter of Electric Vehicles.

Research on Optimization of Horizontal Omnidirectional Misalignment Tolerance of WPT Based on Double D Coupler

DD (Double D) coils have been researched and utilized due to their excellent misalignment tolerance. Here, a compound DD coupler sets for stationary wireless power chargers, which has significantly better anti-misalignment performance than single DD coupler in all directions, is proposed. The transmitting coils are composed of two parts of DD coils wound in opposite directions. Moreover, to obtain the low-level variation of mutual inductance between compound transmitting coils and receiving coils when offset occurs, a parameter optimization strategy of compensation coils is also proposed. With the properly designed parameters, the mutual inductance between transmitting and receiving coils could remain basically constant when misalignment occurs, which means that the efficiency and power remain relatively constant when offset occurs. Finally, both single DD coils and compound DD coils experimental prototypes are built to compare anti-misalignment ability performance. The results show that the proposed system is basically more stable and has a higher output power and more stable efficiency than that of unoptimized coupler during migration. In particular, with the employment of the antiparallel winding, the efficiency fluctuates from 85.5% to 85% when the 0.1-m offset in the X-axis and Y-axis occurs simultaneously. Moreover, the higher and basically more stable output power is also achieved.

Integrated Double-Sided LCC Compensation Topology for an Electric Vehicle Wireless Charging System

Wireless power transfer (WPT) is a necessary solution for removal of high power cables (direct electrical contact) that provides safer charging solution, waterproof and dust-proof capability, sterile environment application, etc. The double-sided LCC (DSLCC) compensation topology offers a high efficient Electric Vehicle (EV) wireless charging operations. Due to the number of elements utilized in DSLCC, it requires large space. In order to reduce the space and cost, class-E converters are utilized to design a low power wireless charging system. Class E converters have such benefits as less components, high reliability, and soft switching. Thus, to have a compact efficient Wireless Charging System (WCS) by reducing the space occupancy of DSLCC, an integrated DSLCC based wireless charging system for low power applications is proposed. This method was realized by utilizing the MATLAB simulation and achieved more than 90% of efficiency for 1 kW system with 85 kHz frequency.

Characteristic Study for Wireless Charging System

Power is an essential requirement in these modern lifestyles. Electronic gadgets like cell phones, laptops, etc., need the least power to charge. The utilization of Wireless Power Transmission (WPT) has been a hot issue among researchers these days. Nowadays, the application of wiring is becoming very inconvenient since everything cannot be used as there are some limitations and dangers. Therefore, several techniques have been found to carry out the wireless charging purpose in this study. The power transmission through the air is much easier to implement, more efficiently and persistently charged without the demand of connection physically. In this paper, a comparison between the three techniques for wireless power chargers has been determined. Among these three, it is found that the utilization of inductive coupling techniques is the best way to implement the system.

전기자동차용 무선 전력 충전의 적정 선정을 위한 자기 공진 회로구조의 비교 분석

In this paper, four circuits of magnetic resonance circuit systems for improving the performance of wireless power charging for electric vehicles were compared and analyzed. Currently, wireless charging is widely used in real life and commercialized, and a wireless charging method is being studied to compensate for the problems of the wired charging method of electric vehicles. In order to wirelessly charge an electric vehicle, a magnetic resonance method is used, and to compare the efficiency of the most basic four magnetic resonance circuit system structures, parameters are obtained through the design formula of the magnetic resonance circuit system, and the efficiency of each magnetic resonance circuit system are compared and analyzed through PSIM.