Coil Wireless Power Transfer System Research Articles

A Double-Transmitting Coil Wireless Power Transfer System Based on Parity Time Symmetry Principle

A Double-Transmitting Coil Wireless Power Transfer System Based on Parity Time Symmetry Principle

Optimal Design of Transmission Characteristics for Hexagonal Coil Wireless Power Transfer System Based on Genetic Algorithm

Effective optimization methods are used to guide the optimal design of coil parameters, which is significant for improving the transmission performance of the wireless power transfer (WPT) system. Traditional methods mostly rely on the exhaustive attack method and finite element analysis (FEA) to achieve the coil parameter design, which have the disadvantages of complex modeling and time-consumption. To overcome these limitations, this study proposes an optimization strategy based on the genetic algorithm (GA), which considers the actual requirements of the efficiency and power of the WPT system. First, a direct integration method is proposed to simplify the analytical solution process of the mutual inductance between the hexagonal coils. Based on the mutual inductance model, the transmission characteristics of the hexagonal coil WPT system are deeply analyzed by the control variable method. Most importantly, with the proposed optimization objective function and its constraints, the GA is used to automatically achieve multi-parameter optimization of the hexagonal coil. Finally, a 500 W WPT system experimental platform is established, and the experimental results verify the feasibility of the proposed optimization method.

PT Symmetry-Based AUV Dual Transmission Coil Wireless Power Transfer System Design

Autonomous underwater vehicles (AUVs) are widely used for ocean exploration; however, the way they are replenished becomes the biggest issue limiting their range and efficiency. A dual transmission coil wireless power transfer (DTCWPT) system based on parity–time (PT) symmetry is proposed in this paper to realize an autoadaptive constant power transmission. A shielded housing structure for coils is equipped to realize WPT in the ocean. In the offset experiments, the proposed dual transmitting coil structure was able to achieve a stable power transmission of 39 W within an offset range of 8.1 cm. It is obvious that the DTCWPT system based on PT symmetry could charge an AUV in the ocean with high robustness. This paper provides a novel solution based on DTCWPT for AUV energy supply. The proposed DTCWPT system could offer remarkable improvements in the navigation performance of AUVs.

A Three-Coil Wireless Power Transfer System using Self-Resonant Open-Bifilar Coils

A common trend in the field of wireless power transfer consists in the use of more than two coils in order to extend the link distance in terms of efficiency, in which the 3-coil system is of great interest due to its high efficiency. In these circuits, usually, the preferred method of compensation is the series (capacitor and inductor in series), mainly due to its simplicity. Another promising topic is the use of coils tuned at their self-resonant frequency, mainly because it could avoid the use of external capacitors to achieve the resonant state in the involved circuits. However a multiple-coil self-resonant frequency with series compensation system was not yet presented in literature. In this paper, using open-bifilar coils, we present a self-resonant 3-coil wireless power transfer system that behaves as common series compensated circuit. Practical results confirm the validity of proposed solution, in a proof of concept methodology, that is, without any optimization strategy applied. For this sake, three different distances between transmitter and relay coil are adopted, while a 10 Ω resistor is used as load, allowing a maximum efficiency of 47% at a distance of 8 cm between relay and load coil (coils diameter are 15 cm).

Analysis and Modeling of a Wireless Power Transmission System for Multiple Receivers

In this article the model for the study of wireless power transfer to several receivers is presented. The problem of determining the ideal loads to obtain the maximum transfer of energy in a connection between a transmitter and several receivers was considered and solved by applying the maximum power transfer theorem for N ports. This condition is derived from the circuit analysis and discussed together with the respective efficiency of the Wireless Power Transfer (WPT) system (). In sequence, it is shown that a WPT system with multiple coils without loss of energy in the two communication circuits presents, from the maximum transfer of power and efficiency point of view, performance similar to that of a 2 coil WPT system. Simple analytical expressions for the load impedances were validated through experiments and circuit simulations. These expressions are also valid in the case of mutual coupling between receivers.

Design and experiment： u-shaped transmitting coil wireless power transfer system for micro gastrointestinal capsule robot

Design and experiment： u-shaped transmitting coil wireless power transfer system for micro gastrointestinal capsule robot

Research on optimal receiver radius of wireless power transfer system based on BP neural network

In order to improve transmission performance of Wireless Power Transfer (WPT) system, this paper proposes the concept of optimal receiver radius. The planar square transmitter coil WPT system is studied to explore the variation rule of optimal receiver radius with the parameters of WPT system. The key parameters that affect optimal radius are transmitter coil turns, turn spacing, side length and transmission distance. On this basis, by introducing BP neural network to learn the variation rule, the accurate prediction of optimal receiver radius under different parameters is realized. Finally, the finite element simulation proves the existence of optimal receiver radius and the accuracy of the prediction value.

Optimal Design of a 3-Coil Wireless Power Transfer System for Deep Micro-Implants

This paper presents a design methodology for a 3-coil magnetic resonance wireless power transfer (WPT) system with a long transfer distance (up to 20 cm) and a small implanted receiver (RX) (2mm in diameter) at a specific frequency. The methodology aims to find out the optimal value of dimensional parameters (i.e., coil diameter, gap interval and coil turn number) of the transmitter (TX) coils to maximize the magnetic field strength at the target distance while keeping the coil self-resonant frequency (SRF) twice of the target operational frequency. Firstly, the circuit model of the TX circuits is developed, which include a single-turn coupling coil and a multi-turn primary coil. Secondly, the co-dependences between the dimensional parameters are analyzed, which shows the dominant factors and secondary factors of each dimensional parameter, and how the optimal values of dimensional parameters are changed by these factors. Based on the analysis, design flow of the TX circuit is proposed to decide the optimal values of dimensional parameters given the transfer distance, source voltage, operational frequency and wire diameter. Using the design flow, optimal values of dimensional parameters are predicted for 20-cm transfer distance and 16-cm transfer distance and are verified with finite element analysis (FEA) software COMSOL Multiphysics. With the optimal TX design, the power received by a 2-mm ferrite core solenoid RX is calculated. At 20 cm transfer distance, up to 4.3 mW can be achieved in air, and 0.8 mW can be achieved in conductive human tissue.

Cross Interference Minimization and Simultaneous Wireless Power Transfer to Multiple Frequency Loads Using Frequency Bifurcation Approach

Simultaneous power distribution to multiple loads using a single source in the wireless power transfer (WPT) system is a challenging issue due to cross-coupling between the load coils, which reduces the power transfer efficiency. In a resonant WPT system, when two or more coils operated under over coupled condition, the original operating resonant frequency gets bifurcated, and thereby reduction in the power transfer efficiency. Different techniques are investigated in the literature to mitigate the frequency bifurcation phenomena in the resonant WPT system. However, the utilization of frequency bifurcation approach for the simultaneous power transfer to multiple loads is not addressed. This paper proposes a simultaneous power transfer approach using frequency bifurcation for the multiple load system designed with different operating frequency. Mathematical, simulation, and experimental studies performed for dual, triple, and four coil WPT systems with multiple loads. In addition, an automatic power flow control method is implemented to estimate the load current from the source, which helps to select a new set of load coils to be charged. The experimental results confirm the proposed power transfer, helps to attain higher power transfer efficiency of 39.34%, 49.31%, 68.22% and cross interference of −31.2 dBV, −36.2 dBV, −41.2 dBV for dual, triple, and four coil WPT system, respectively.

High Efficiency Tracking Scheme for Magnetic Resonance based Wireless Power Transfer System

Objective: The motivation of the work is to track the maximum efficiency of magnetic resonance based wireless power transfer system which uses either two, three or four coils. Analysis: The system consists of two sections namely transmitter side and receiver side, where the supply is given to the transmitter side and when any receiver is connected to the load by tracking the maximum energy efficiency operating point of the system and controlling the duty cycle ratio. The analysis is carried out for 2, 3 and 4 coil system in simulation and experimental test setup. Findings: This paper implements the maximum energy efficient tracking method for the 2, 3 and 4 coil wireless power transfer system. Applications: This system can be employed in electric vehicle charging, Bio implants, micro robots and so on.

Experimental Analysis of 2,3 and 4 Coil Wireless Power Transfer System with Different Medium and Distance

Objective: The main theme of this paper is to analyze the wireless power transfer system efficiency in real time with different medium, distance and angle between the source and load coil. Analysis: The transmitter side of Wireless Power Transfer (WPT) system connected to the supply and receiver side is connected with load. The analysis is carried out for 2, 3 and 4 coil system in experimental test setup. Based on the experimental results it has been observed that the 4 coil WPT system gives better performance as compared with other two. Also it shows higher efficiency, if the angle of orientation of the load coil is small with the source coil.Findings: The four coil WPT system can be used in low power wireless charging devices with the distance of 3 to 15c.m between transmitter and receiver. Application: This system can be employed in electric vehicle charging, Bio implants, microrobots and so on.

Characteristics analysis on a superconductor resonance coil WPT system according to cooling vessel materials in different distances

The interest in wireless power transfer (WPT) that can send power without using wires has been increasing recently. Especially, there is a great interest in the wireless power devices for portable IT devices. The WPT devices that have been developed so far use the magnetic induction method, and they are not active due to their distance problem. A magnetic resonance WPT method was developed and has been actively researched to resolve this problem. A superconductor coil was applied in this study to increase the efficiency of the magnetic resonance WPT. FRP, bakelite, polystyrene, aluminum, and iron were applied as the cooling vessel material to analyze the WPT distance. The distance between the transmitter and receiver coils started from 800mm and was increased by 200mm. The reflection coefficient was measured at each distance. As a result, FRP, bakelite, plastic PVC, polystyrene of the reflection coefficient was similar. From among these FRP being used for the cooling vessel made the transmission characteristics higher than any other materials when the distance between the transmitter and receiver coils was 2,000mm. On the other hand, the reflection coefficient dropped when iron was used. It is estimated based on the experimental results that the wireless power transmission characteristics and distance of sending power can be improved in the superconductor coil if the cooling vessel is made with FRP.

Optimal single relay position of a 3‐coil wireless power transfer system

It seems a good idea to place the relay coil in the middle to maximise the load voltage in a 3-coil wireless power transfer system; however, no literature points out clearly the reason and the necessary conditions that it holds. In this study, the complex relationship between coupling coefficients and distances is approximated by a simple polynomial, and then a rigorous analysis is carried out to show clearly that the optimal relay coil position of a 3-coil wireless power transfer system is just the middle of the drive loop and the load loop under the symmetrical condition that coil quality factors of the drive loop and the load loop are equal, and furthermore the middle is not the optimal position if the symmetrical condition is destroyed. Finally, the theoretical results are confirmed by the physical experiments.

On the analysis of using 3-coil wireless power transfer system in retinal prosthesis.

Designing a wireless power transmission system(WPTS) using inductive coupling has been investigated extensively in the last decade. Depending on the different configurations of the coupling system, there have been various designing methods to optimise the power transmission efficiency based on the tuning circuitry, quality factor optimisation and geometrical configuration. Recently, a 3-coil WPTS was introduced in retinal prosthesis to overcome the low power transferring efficiency due to low coupling coefficient. Here we present a method to analyse this 3-coil WPTS using the S-parameters to directly obtain maximum achievable power transferring efficiency. Through electromagnetic simulation, we brought a question on the condition of improvement using 3-coil WPTS in powering retinal prosthesis.