Intermediate Coil Research Articles

A Reconfigurable IPT System With CC‐CV Output Characteristics and High Misalignment Tolerance

ABSTRACTMisalignment between transmission coils is an inevitable challenge in inductive power transfer (IPT) systems, particularly affecting the constant current (CC) and constant voltage (CV) outputs essential for battery charging. A reconfigurable IPT system with high misalignment tolerance and CC‐CV output characteristics is proposed in this article. The main circuit of the system is composed of a LCC‐LCC and LCC‐S topology with two intermediate coils, and two switches equipped with single unidirectionally blocking MOSFETs are incorporated on the secondary side to transition from CC to CV mode. A comprehensive analysis of the output characteristics for the proposed hybrid topology in both CC and CV modes is provided. Furthermore, the parameter optimization design based on BP coil for wide misalignment tolerance is presented. The experimental results demonstrate that the proposed reconfigurable IPT system can maintain stable CC and CV outputs within 50% lateral and vertical offset (the coupling factor varies from 0.1 to 0.21), when the load varies from 11 to 80 Ω, and the output current and voltage fluctuations remain below 5%.

Wireless Charging System With Dual Switchable Constant Voltage and Constant Current Outputs Based on Intermediate Coils

Wireless Charging System With Dual Switchable Constant Voltage and Constant Current Outputs Based on Intermediate Coils

30kW Bidirectional Inductive Power Transfer Charger with Intermediate Coil for EV Applications

30kW Bidirectional Inductive Power Transfer Charger with Intermediate Coil for EV Applications

Improvement in Power Transmission Efficiency of Wireless Power Transfer System Using Superconducting Intermediate Coil

We have demonstrated that using a high-quality-factor intermediate (IM) coil with a high temperature superconductor (HTS) wire improves the power transmission efficiency (PTE) of a wireless power transfer (WPT) system for long-distance power transmission. The IM coil is placed at the center of Cu transmitting (Tx) and receiving (Rx) coils and consists of a previously developed double-sided HTS coated conductor (CC) wire. A WPT system with the HTS IM coil was designed on the basis of the design theory for a third-order bandpass filter. The measured PTE of the system was compared with that of one with a Cu IM coil. The resonant frequencies of the Tx, Rx, and IM coils in both systems were each about 9 MHz. When the distance between the Tx and Rx coils was 160 cm, the PTEs of the systems were 49.7% and 17.5%, respectively, demonstrating that the PTE of a WPT system can be greatly improved by using an HTS IM coil rather than a Cu one.

A Misalignment Tolerate Integrated S-S-S-Compensated WPT System with Constant Current Output

This paper proposes a cooperative (Cx) coil design for the series-series-series (S-S-S)-compensated wireless power transfer (WPT) system to improve the horizontal misalignment tolerance and the system efficiency. The Cx coil is formed by four series-connected rectangular coils and integrated into the transmitter (Tx) coil to provide a coupling variation opposite to that of the Tx coil, obtaining the constant equivalent mutual inductance (MI). The design overcomes the problem that the decoupling-designed intermediate coil does not participate in system energy delivery under the well-aligned condition. A misalignment tolerant design with the zero-phase-angle (ZPA) input and load-independent constant current (CC) output conditions is presented based on the Delta-Wye network transform and linear regression. A comparison between the proposed design and a two-coil system using a similar amount of copper, i.e., the Tx coil plus the Cx coil, is made. Finally, a 218.08 W/85.85 kHz scaled-down prototype with the proposed Cx coil is demonstrated to validate the performance and effectiveness of the design. The proposed design can maintain at over 82% efficiency, and offer the ZPA input and load-independent CC output within a misalignment tolerant range of 50% of the length of the receiver coil, as the load varies from 10 Ω to 25 Ω.

Misalignment Tolerance Improvement for Loosely Coupled Transformer of IPT Systems via an Intermediate Coil With Detuned Compensation

Misalignment Tolerance Improvement for Loosely Coupled Transformer of IPT Systems via an Intermediate Coil With Detuned Compensation

A Hybrid IPT System Implementing Misalignment Tolerance and Constant Current Output With Primary Intermediate Coil

Inductive power transfer (IPT) systems have advantages of safety, flexibility, and convenience compared to plug-in charging systems. However, in practical applications, pad misalignment is still an almost inevitable issue which may cause variation in magnetic couplings, thus affecting the power transmission and reducing the system efficiency. Therefore, IPT systems are usually expected to achieve tolerance for misalignment. To fulfill this feature, a hybrid IPT system is proposed in this article. By adopting two coils compensated by different topologies in receiver side and an additional intermediate coil in transmitter side, load-independent constant output current with improved misalignment tolerance can be achieved. In addition, when the receiver pad is very far away from the transmitter pad, the proposed system can operate safely due to the inherent limitation ability of the primary inverter current. The design process is presented to optimize the misalignment performance. Based on the experimental results of a 3.3-kW prototype, the fluctuation of the output current is less than 5% within ±300-mm misalignment in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$y$ </tex-math></inline-formula> -axis, −30- to +60-mm misalignment in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$z$ </tex-math></inline-formula> -axis, and −80- to +60-mm misalignment in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$x$ </tex-math></inline-formula> -axis. The system efficiency is 96.7% at nominal operating point (NOP) and varies from 94.7% to 97.8% with variable loads and misalignment.

Distributed Control System for Agrotechnical Processes Using Customizable Procedural Regulations

Nowadays, the technical and technological capabilities achieved in the field of agriculture permit to implement quickly convertible (adaptive) crop production systems. This, along with increased efficiency, also greatly complicates the management process. Automated control systems (ACS) with adaptive properties are needed. The concept of creating an ACS assumes the implementation of the principle of modularity and flexible changes in the structure of the management hierarchy, powers, tasks and functions for geographically distributed decision-making centers and executors. Key technologies in the design of such ACS are: synthesis of a temporary control loop from geographically distributed elements and synthesis of procedural regulations for a decision-making center included in the temporary control loop. The article formulates the problem of synthesis of procedural regulations in the form of a tensor transformation problem of the original electrical network (library of procedures) into a network with specified properties. A method for obtaining the tensor equation of transformation of the original network is presented based on the requirements for the composition of the input and output data of the synthesized procedural regulations. The solution obtained after tensor transformation has the form of a matrix of connections and a vector of voltages on the intermediate coils of the original electrical network (library of procedures). This forms structural links for the synthesized procedural rules. The demonstrated approach can be extended to solve a wide range of problems of adaptive changes in the structures of organizational management systems.

Реалізація прийняття рішень організаційного управління на основі онтології діяльності

The complexity of the tasks of making decisions in organizational management is stipulated by the extremely large dimension of the management space, the weak structure of the tasks being solved due to their uniqueness, the uncertainty of conditions, and the changeability of the goals (aspects) of management. The ontological approach provides a range of advantages in solving the problem of organizational management automatization. The use of the activity ontology makes it possible to significantly expand the scope of formalized methods application to organ-izational multi-aspect management. Due to the ontology, the detailing of managerial alterna-tives is increased, and the factors of the performers’ activity and the multi-aspect nature of management are taken into account. The article considers the interpretation of the process of forming managerial alternatives as a process of the threefold grouping of elements of the activi-ty ontology and discrete moments of time. The method of distributed formation of an ontologi-cal network with the grouping of its elements using expert methods, implemented in the prac-tice of designing corporate ACS, is described. The topical scientific tasks of the development of the scientific and methodological apparatus of organizational management based on ontology are formulated. These tasks include the formation of decision-making spaces that are invariant to aspects of management, the concretization of characteristics-invariants and reconfiguration of procedural regulations concerning the actual aspect of management, synthesis of alternatives based on the ontology elements. Some approaches to solving the formulated tasks are shown. The formulation of the problem of synthesizing a system of procedures with given input and output parameters is presented as a problem of tensor transformation of an initial multi-coil electrical network (library of procedures) into a network with the given parameters. A tensor equation is proposed. Its solution allows determining the values of voltages on the intermediate coils of the original electrical network which forms the structural connections for the synthe-sized procedural regulations.

Development and analysis of three‐coil wireless charging system for electric vehicles

SummaryWireless charger has become a potential solution for charging electric vehicles (EVs) due to its intrinsic convenience and further scope of countering range anxiety issue. However, ground clearance of the EVs varies with the vehicle type, manufacturer, and so on, which reduces the power transfer efficiency (PTE) and power delivered to load (PDL) by the wireless charger. To overcome these limitations, this paper focused to revamp the design of a three‐coil wireless charging system through optimized size and position of intermediate coil (InC). Further, the system is tested for different loads at different input voltages, misalignment conditions, and distances for 100‐kHz frequency and compared with a two‐coil system under the same conditions. Angular misalignment of InC near the transmitter coil (TxC) (50‐mm gap) showed increased efficiency compared to other misalignment conditions. Three‐coil system results at different distances of InC from TxC showed that the maximum efficiency region shifted to different loads. Maximum efficiency for designed three‐coil was achieved when the InC was placed in the center between the TxC and RxC. Maximum efficiency for power transfer distance (D) of 150 and 200 mm obtained are 76% and 70% for 25Ω and 35Ω.

Wireless Power Transfer Systems Optimization Using Multiple Magnetic Couplings

Multiple magnetic couplings used to increase the link distance in wireless power transfer systems (WPTSs) are not new. An efficient power transfer in conditions of an extended link distance requires a series connection of the intermediate coils. However, all four connections of the emitter and receiver coils are equally possible. This present paper conducts an extensive analysis of WPTSs utilizing three magnetic couplings. The type of connection of the emitter and receiver coils represented the criterion utilized for the WPTS optimization assessment. The first step requires the determination of the schematic of the sinusoidal equivalent circuit. Then, one synthesizes the functions describing the system performances (e.g., the amount of delivered active power or efficiency) by applying the entirely symbolic and or the hybrid symbolic-numerical formalism. The output of such functions consists of appropriate representation in the frequency domain, based upon Laplace state variable equations (SVE) or complex or Laplace modified nodal equations (MNE). The dependency of the WPTS performance on the number of magnetic couplings and their parameters included a study on resistive loss minimization. The minimization applies to the intermediate coils, whereas the outcomes are the active delivered power and the power transfer efficiency—the first study case aimed at a comparison between two distinct WPTSs: three magnetic couplings versus two. The second case of the study compared the WPTSs having a series connection of three magnetic couplings with those built with the emitter-receiver resonators in parallel. One determined the normalized sensitivities as frequency functions, which depend on circuit resistances, load resistance and the coupling factor between the second and the third coil. The optimization algorithms are suitable for computing optimal parameters of the given circuit to ensure maximum and minimum values of the performance value. Good simulation examples followed the proposed optimization techniques.

Calculating the magnetic force of solenoid inductor wound by rectangular cross‐section wire

A new semi-analytical expression is presented based on two integrations for calculating the magnetic force of a solenoid inductor wound by rectangular cross-section wire. The authors simplified the solenoid inductor coil to a collection of circular coils, and the current density of the coils in the radial direction which was inversely proportional to its radius is considered. The obtained expressions can be implemented by adaptive Gaussian quadrature integration with MATLAB programming. In addition, they used the filament method and the finite element method to calculate the magnetic force on the solenoid inductor coil. The correctness of the semi-analytical expressions was verified by comparing the results of the semi-analytical numerical method with those of the filament method and the finite element method, respectively. The derived semi-analytical expressions of magnetic force allow a low computational time compared with the filament method and the finite element method to a specific accuracy. The calculation results show that: the solenoid inductor coil tends to compress in the axial direction, and the axial magnetic force on the outermost coils is the largest; the solenoid inductor coil tends to expand outward in the radial direction, and the radial magnetic force on the intermediate coil is the largest.

High Misalignment Tolerance in Efficiency of WPT System With Movable Intermediate Coil and Adjustable Frequency

Offsets between the primary and secondary coils of loosely coupled transformers (LCT) are attributable to the efficiency decline of the wireless power transfer (WPT) system. To improve the misalignment tolerance of efficiency in WPT system, this paper presents a LCT system with a movable intermediate coil and adjustable system frequency, which can promote the efficiency of the WPT system under misalignment condition. First, the influences of the position and compensation parameter of intermediate coil on the system efficiency during migration are summarized. The optimal compensation parameter and optimal position selection method of intermediate coil are proposed. Then, the influence of frequency on system efficiency is studied, and the detailed control strategy of intermediate coil’s position and system frequency is proposed. A 3-kW prototype WPT with the proposed three-coil LCT is manufactured and experimental validations are also performed. The results show that the efficiency declines of three-coil LCT with the proposed control strategy is 1.8% when the lateral offsets reach 300mm, namely 43% of the outer diameter of coil.

Optimal Position of the Intermediate Coils in a Magnetic Coupled Resonant Wireless Power Transfer System

Coaxial coil topology is used as the transfer medium in traditional MCR-WPT (Magnetic Coupled Resonant Wireless Power Transfer) systems to improve the transfer characteristics. The intermediate coils are added to extend the transmission distance, whose positions are critical. This paper focuses on the optimal intermediate coil positions for an MCR-WPT system with four coaxial planar circular spiral coils. By modeling the MCR-WPT system, the mathematical expression of the self-inductance and the mutual inductance are used to calculate the load power of the MCR-WPT system, which is composed of four planar circular spiral coaxial coils, and using MATLAB. The optimal distance ratio between the adjacent coils for maximizing the power of load is proposed. Furthermore, the experiments are implemented from the network analyzer and the experimental platform. In the platform, the load power is measured at the different intermediate coil positions, and the optimal position at which the load power is maximized is found. Both experimental results obtained by the network analyzer and the experimental platform have validated the theoretical and simulation results and provided the correctness of the suggested ratios.

Design and voltage regulation of inductively coupled wireless power transfer circuits with an intermediate coil

An inductively coupled wireless power transfer (WPT) circuit consisting of the transmitter, the receiver, and an additional intermediate coil is studied. It is assumed that the intermediate coil is located coplanar with the transmitter coil. Although it has been known that the intermediate coil serves as a power repeater, its effect on the three-coil WPT circuit characteristics has not been thoroughly investigated. Accordingly, this study analyses how the intermediate coil affects the voltage transfer function and the input impedance of the WPT circuit. Based on the analysis result, design considerations are presented and output voltage regulation via operation frequency adjustment is discussed. A design example for the three-coil WPT circuit is presented and the simulation and experimental results are provided.

A Misalignment Tolerant IPT System With Intermediate Coils for Constant-Current Output

Misalignment in an inductive power transfer (IPT) system is inevitable for most of the cases, which leads to system performance degradation due to the variation of system parameters. A novel IPT topology with two intermediate coils, one for primary side and the other for secondary one, is proposed to improve an anti-misalignment characteristic. With the merit of the proposed topology, a constant-current output characteristic is achieved, and the system can operate safely without any secondary side. Then, the parameter design and optimization method of the magnetic coupler with intermediate coils are elaborated to improve misalignment performance. Finally, a 3.4-kW experimental setup is built to verify the feasibility of the proposed method. Experimental results show that the four-coil IPT system can tolerate ±225 mm X- misalignment, −30 to +50 mm Y- misalignment, and −20 to +70 mm Z- misalignment with load varying from 40 to 60 Ω, while the fluctuation of the output current is within ±5%. The system efficiency of the IPT system is from 92.1% up to 96.3% with misalignment and variable load (40–60 Ω).

Design and Analysis of Quasi-Omnidirectional Dynamic Wireless Power Transfer for Fly-and-Charge

This paper proposes and implements a novel quasi-omnidirectional dynamic wireless power transfer (WPT) system using double 3-D coils for drone applications. In the traditional omnidirectional WPT system, the receiver direction is always facing the 3-D transmitter center to maximally pick up the magnetic flux. However, the on-drone receiver normally proceeds horizontal or vertical movements so that it is unable to fully utilize the magnetic flux and result in serious magnetic flux leakage. Thus, by newly proposing the 3-D intermediate coil and artfully aligning specific quadrant of double 3-D coils to the center of the flying area, the proposed WPT system can flexibly and efficiently power the drone in the specific space. Moreover, only one single power source is needed to drive the transmitter coil without using the sophisticated current phase control. Therefore, the proposed system can simultaneously achieve both quasi-omnidirectional WPT and dynamic WPT for the drone so that its flying time can be significantly extended. The theoretical, simulated, and experimental results are given to validate the feasibility of the proposed WPT system.

Reconfigurable Intermediate Resonant Circuit Based WPT System With Load-Independent Constant Output Current and Voltage for Charging Battery

In this letter, a compact battery charger based on wireless power transfer (WPT) technology without any communication requirement is proposed. Here, a new intermediate coil is developed to achieve load-independent constant current (CC) and constant voltage (CV) outputs. The intermediate coil is split into two coils and is overlapped with the receiver coil to form a compact structure. Two switches on the receiver side are used to reconfigure the intermediate resonant circuit in order to select different charging modes, i.e., CC mode or CV mode. The communication between the transmitter side and the receiver side as well as complex control strategies is not needed in the proposed structure. Besides, the proposed system can achieve zero phase angle operation, fixed operating frequency, and zero-voltage switching, which not only can lower the power rating of power devices but also improve the efficiency. A laboratory prototype with a 3.6 A charging current and a 48 V charging voltage is built to verify the feasibility of the proposed method.

Three-coil Magnetically Coupled Resonant Wireless Power Transfer System with Adjustable-position Intermediate Coil for Stable Transmission Characteristics

Three-coil Magnetically Coupled Resonant Wireless Power Transfer System with Adjustable-position Intermediate Coil for Stable Transmission Characteristics

Optimization of Time-Weighted Average Efficiency for Reconfigurable IPT Battery Charging System

Constant current (CC) and constant voltage (CV) combined charging is considered as the most popular and efficient method for charging batteries. There are a lot of works done to achieve CC/CV characteristics by utilizing reconfigurable circuits for easy control but without the consideration of efficiency optimization in the CV mode. In this paper, the optimization of mutual-inductance proportion between transmitter/receiver mutual inductance and transmitter/intermediate mutual inductance of the three-coil circuit is investigated to maximize the time-weighted average efficiency (TWAE). With two switches, a section of receiver coil of the series-series (SS) circuit, which corresponds to the optimized mutual inductance proportion, can be converted into an intermediate coil of the three-coil circuit. Therefore, the system can be transferred from the CC mode to CV mode, and with the optimized mutual-inductance proportion, the efficiency in the CV mode can be improved. An experimental prototype is built to validate the feasibility of the proposed approach. In the CC (CV) mode, the impedance range is 30-108 Ω (108-500 Ω), and the maximum fluctuation for current (voltage) is 3.37% (4.55%). Besides, the TWAE is 94.5% (maximum 95.3% and minimum 94.49%) for the three-coil circuit, while that of SS circuit with control is 91.54% (maximum 95.20% and minimum 85.31%).