A 402 MHz and 1.73-VCE Resonance Regulating Rectifier With On-Chip Antennas for Bioimplants.

This paper presents the design and modeling procedure of a wireless power transfer (WPT) system applied to In-wheel-motor (IWM). The system is designed to transmit over 10 kW of power following the physical constraints faced by the IWM applications. The issues of coil misalignment and load change are discussed as particular scenarios in IWM. The finite element model is built for circular, rectangular, and double-D coils, finding that the rectangular coil has the best performance considering the transmission interval and misalignment resistance. The circuit design procedure is presented, and the analysis of the influence of load and mutual inductance change on the WPT system is addressed. Finally, the performance of the design is verified with experiments on a full-scale prototype. It is proved that the WPT system successfully transmits 10 kW of power with a DC–DC efficiency of over 90% under a transmission interval of 140 mm. The output voltage is stable under 40 mm coil misalignment scenarios and over 50% load change.

To ensure electric energy supply at arbitrary directions, omnidirectional Wireless Power Transfer (WPT) system is gaining increasing attention. The cubic structure with three orthogonal coils is becoming one of the optimal technical solutions for omnidirectional WPT system. In this paper, the transfer characteristics, such as load resistance changing and coupling coefficient changing, of a three-transmitter and three-receiver WPT system are analyzed and compared with those of a conventional single-transmitter and single-receiver WPT system. According to the electric circuit theory and 1:1 WPT system model, the theoretical model of M:N WPT system is derived and generalized. And then, a set of 3D orthogonal coils is designed and trial-manufactured for testing the transfer characteristics of the 3:3 WPT system. At last, an experimental platform is built up to test and compare the transfer characteristics of both 1:1 and 3:3 WPT systems. The tested results show that the theoretical analysis is correct and the maximal transmission power is 150W and the maximal transmission efficiency is 43.6% when the 3:3 WPT distance is 20cm. Furthermore, the designed 3:3 WPT system can realize full-space energy transmission for electronic equipment and the output stability can maintain high when the coil spatial offset occurs.

This paper presents the analysis and design of the wireless power transfer (WPT) system based on the inductor‐capacitor‐capacitor/none (LCC/N) magnetic integration compensation circuit. Compared with the traditional compensation circuits, the proposed LCC/N compensation circuit features the magnetic integration and the secondary side without compensation network, which makes the WPT system more compact. First, the fundamental‐harmonic model considering the coupling relationship among magnetically integrated compensation inductor, transmitter coil, and receiver coil is established. Then, the reactive power and turn‐off current of the inverter, transmission power, and efficiency of the WPT system employing LCC/N compensation circuit are analyzed with varied coupling coefficient and load. Furthermore, based on the characteristics analysis of the LCC/N topology, the parameter design criterion of the LCC/N compensation circuit is given. Finally, the analysis and design of the WPT system based on the LCC/N magnetic integration compensation circuit are verified by simulations and experiments. The results show that the characteristics analysis of the WPT system employing the LCC/N compensation circuit is accurate, the inverter can realize zero‐voltage‐switch (ZVS) and the WPT system can achieve the rated power of 1 kW under different offset distances of coils and reach the maximum efficiency of 95.3%.

In order to improve the efficiency of wireless power transfer (WPT) system, the spatial fields are regulated on a two-non-resonant-coil WPT system by hexagon artificial magnetic conductors (AMC). In our configuration, the AMC is located by the side of the two-non-resonant-coil WPT system and close to the transmitter coil. The AMC structure consists of small hexagon copper patches periodically arranged on the dielectric substrate. Each patch is grounded by a via passing through its center hole. Chip capacitors are soldered in the gaps between the adjacent patches. We can design the working frequency of WPT system through the capacitance of these chip capacitors. The results show that the electromagnetic fields are changed between the transmitter coil and the receiver coil in WPT system due to the introducing of the AMC structure. There are two main reasons. First, many resonant modes are excited by near magnetic fields on the AMC structure. Second, near magnetic fields are shielded by the AMC structure. The variation of space electromagnetic field improves the transmission efficiency of WPT system. When the working frequency is 27 MHz and the transmission distance is 3 cm, the experiment verifies that the transmission efficiency increases by 22% in the WPT system with the AMC structure compared with the WPT system without the AMC structure. Simultaneously, the transmission efficiency is raised by 25% at different transmission distances. The simulation results are almost consistent with the experimental results. There is a little difference that the number of resonant modes is different between the simulation and the experiment due to the resistance loss of the chip capacitors in experiment. Therefore, we correct the simulation results under consideration of resistive loss. In addition, the excited multiple resonant modes can supply multiple and adjustable working frequencies in the WPT system with the AMC structure. In practical applications, AMC is low in cost and easy to implement.

Underwater wireless power transfer (UWPT) system has attracted widespread attention. It has been used for power delivery for underwater equipment in the marine environment with high safety and convenience. However, the material of metal plates and the shape which will affect the high frequency alternating electromagnetic fields and the high frequency alternating electric fields for the inductive wireless power transfer (IPT) system and the capacitive wireless power transfer (CPT) system. This paper presents the effects of the hull of the autonomous underwater vehicle (AUV) on the underwater wireless power transfer system including the underwater capacitive wireless power transfer (UCWPT) system and underwater inductive wireless power transfer (UIWPT) system. The features of underwater wireless power transfer systems have been carefully studied with simulation and experimental work. The experimental water tank has been constructed with the 35‰ salinity water. The hull of AUVs has been respectively simulated and built with rectangle metal plates and curved metal plates. The original experimental data and phenomenon have been presented in this paper. The different performance of the UCWPT system and UIWPT system is provided and discussed in this paper. The comparison work with the related paper has been analyzed. This paper could be acted as the reference for designing the underwater wireless power transfer system for AUVs.

The performance of wireless power transfer (WPT) systems depends on antenna radiation efficiency and operating resonant frequency. In HF WPT systems, nearby objects have a certain impact on antenna characteristics and consequently on the WPT system performance. In this paper, human-WPT system interaction is investigated in order to provide basic recommendations regarding WPT system design and the human exposure to WPT systems. Preliminary results show that an efficient WPT system with four-arm SHAs is less susceptible to the degradation of system performance due to the influence of the nearby fantom, in comparison with the inefficient WPT between spirals. Also, it is possible to achieve a smaller risk of the electromagnetic human exposure to WPT systems when using an efficient WPT system rather than an inefficient one or a standalone transmitter.

Most of the coil designs for wireless power transfer (WPT) systems have been developed based on the “single transmitter to a single receiver (S-S)” WPT systems by the empirical design approaches, partial domain searches, and shape optimization methods. Recently, the layout optimizations of the receiver coil for S-S WPT systems have been developed using gradient-based optimization, fixed-grid (FG) representation, and smooth boundary (SB) representation. In this paper, the new design optimization of the transmitter module for the “single transmitter to multiple receivers (S-M)” WPT system with the resonance optimization for the S-M WPT system is proposed to extremize the total power transfer efficiency while satisfying the load voltage (i.e., rated power) required by each receiver and the total mass used for the transmitter coil. The proposed method was applied to an application model (e.g., S-M WPT systems with two receiver modules). Using the sensitivity of design variables with respect to the objective function (i.e., total power transfer efficiency) and constraint functions (i.e., load voltage of each receiver module and transmitter coil mass) at each iteration of the optimization process, the proposed method determines the optimal transmitter module that can maximize the total power transfer efficiency while several constraints are satisfied. Finally, the optimized transmitter module for the S-M WPT system was demonstrated through comparison with experiments under the same conditions as the simulation environment.

<p>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.</p>

The objective of this paper is to study a 22 kW high-power wireless power transfer (WPT) system for battery charging in electric vehicles (EVs). The proposed WPT system consists of a three-phase half-bridge LC–LC (i.e., primary LC/secondary LC) resonant power converter and a three-phase sandwich wound coil set (transmitter, Tx; receiver, Rx). To transfer power effectively with a 250 mm air gap, the WPT system uses three-phase, sandwich-wound Tx/Rx coils to minimize the magnetic flux leakage effect and increase the power transfer efficiency (PTE). Furthermore, the relationship of the coupling coefficient between the Tx/Rx coils is complicated, as the coupling coefficient is not only dominated by the coupling strength of the primary and secondary sides but also relates to the primary or secondary three-phase magnetic coupling effects. In order to analyze the proposed three-phase WPT system, a detailed equivalent circuit model is derived for a better understanding. To give a design reference, a novel coil design method that can achieve high conversion efficiency for a high-power WPT system was developed based on a simulation-assisted design procedure. A pair of magnetically coupled Tx and Rx coils and the circuit parameters of the three-phase half-bridge LC–LC resonant converter for a 22 kW WPT system are adjusted through PSIM and CST STUDIO SUITE™ simulation to execute the derivation of the design formulas. Finally, the system achieved a PTE of 93.47% at an 85 kHz operating frequency with a 170 mm air gap between the coils. The results verify the feasibility of a simulation-assisted design in which the developed coils can comply with a high-power and high-efficiency WPT system in addition to a size reduction.

In this paper, we first proposed a novel hybrid loop array (HLA) for low leakage electromagnetic field (EMF) level and high efficiency in a wireless high power transfer system. The proposed HLA effectively enhances the system efficiency and shields leakage EMF in a wireless power transfer (WPT) system using kHz range resonant frequency. The key originality of the proposed HLA is the combination of two types of loop coil; shielding loop coil (SLC) and amplifying loop coil (ALC). SLCs reduce leakage EMF, and ALCs significantly enhance the magnetic field from a Tx coil. The simulation and experiment results show that the proposed solution successfully overcomes the limitations of the existing solutions. Analytical modeling and design procedure are introduced and discussed. In addition, the experimental verification of the simulation result is included. We first designed and modeled an HLA considering the coupling effect of neighboring loop coils to evaluate its efficiency and leakage EMF. With the proposed HLA, we demonstrated a 9.36% improvement in the efficiency and 3 dBm reduction in the leakage EMF near the WPT system.

Nowadays, magnetic coupling is becoming more and more popular as one mean of transferring power energy over medium distance for loosely coupled wireless power transfer (WPT) systems. However, the DC-DC converters in WPT systems are inherently time-varying and nonlinear as for their switching operation, it's difficult to get enough output voltage with stability and high efficiency. This paper proposes one method to maintain the stability of WPT systems using operator theory and the tracking performance is achieved. Also, one proposed voltage reference set can be used to achieve high efficiency in WPT systems. In the end, simulation results are shown to confirm the effectiveness of the proposed method.

The wireless power transfer (WPT) system for electric vehicles requires high efficiency, lightweight, compact and be suited to big air gap. The WPT system has low coupling coefficient, which is far different from the traditional transformer. Optimal parameters design approach for resonant converter with S-S compensation for WPT is investigated. 85kHz and 20kHz parameters design are introduced in the paper. The validity of the proposed parameters design of 85kHz and 20kHz are verified by experimental results obtained from a 10kW resonant converter prototype with 150mm air gap. Finally the results of 85kHz and 20kHz optimal parameters design experiment are compared.

This paper presents a newly-designed optimal current algorithm for high-temperature superconductor (HTS)-based multi-input wireless power transfer (WPT) systems. In this way, both high controllability and lower AC losses can be achieved in the proposed systems, and they are especially superior for long-range and long-time operations. Simplified AC loss modeling for HTS windings is developed for the designed transmitter coils. The accordant optimal current vector is derived and analyzed in order to achieve the highest output power and the lowest primary AC losses. With the proper current control of multiple transmitters and the use of a designed HTS coupler, the system controllability can be greatly improved compared with conventional WPT systems. Based on the information on the impedance characteristics on the primary side, the magnetic field generated by different transmitters can be maximized at the target position. Thus, the maximum output power tracking can be realized with a relatively long transmission distance and a low coupling coefficient. Both active and passive solutions are designed and presented to deal with the cross-coupling issue in multi-input WPT systems. For numerical validation, a practical prototype of the HTS couplers is fabricated. An experimental platform is established with a liquid nitrogen cooling system. The test results further validate the feasibility and the high controllability of the proposed system.

In this paper, a self-excited inverter is utilized to construct the inversion stage of the wireless power transfer (WPT) system without the PWM generator and digital signal processor, which could dramatically simplify the hardware structure. Meantime, soft-switching and automatic frequency tracking could be achieved without additional strategies which also decrease the complexity in control. Generally, in a WPT system, the current of primary-sided coils is expected to be kept constant despite the variation of load, which is helpful to achieve the constant voltage (CV) or constant current (CC) output of the WPT system. Accordingly, the parallel-series (PS) resonance topology is utilized to achieve the high robustness of the primary-sided current without additional compensation networks. The analysis and design procedure for the WPT system are provided and a low-power prototype is built. The simulation and experimental results validate the design of the WPT system. When the load resistor changes from 30Ω to 10 Ω, the fluctuation of primary-sided current is only 4.3%, and a dc–dc transfer efficiency of 85.82% with a 9-cm distance and 73.16-W output power is reached.

In wireless power transfer (WPT) system, the structure of coils can affect the power and efficiency performance of WPT system. In this paper, transmission coils with different structures is designed and analyzed in magnetically coupled resonant WPT system. An eight-Figure coil structure is designed. Moreover, an array is built by two eight-Figure coils. The system is simulated under the same magnetic excitation. Finite element method is used to simulate transmitting coils to obtain the distribution of magnetic fields. The current and voltage of eight-Figure coil WPT system are analyzed in the case that receiver shifts from middle axis. The current and voltage of from 50 mm and 200 mm above transmitting coil under the same excitation are compared. The results show that eight-Figure coil is able to relieve coil misalignment issue in WPT system. Moreover, coil array can reduce the influence of the radial offset to entire WPT system.