Omnidirectional Wireless Power Transfer System Research Articles

Research on Maximum Power Point Tracking Control in Omnidirectional Wireless Power Transfer System

Research on Maximum Power Point Tracking Control in Omnidirectional Wireless Power Transfer System

A multi‐receiver adaptive design of variable magnetic coupled structure for omnidirectional WPT system

SummaryOmnidirectional Wireless Power Transfer (OWPT) system can provide power to multiple loads in space. The different loads have different requirements for current and power levels under various operating conditions. This paper proposes a Variable Receiving Coil (VRC) structure and its control strategy. Active regulation of the output current is achieved by adjusting the geometric size of the receiving coil. Meets the power supply needs of equipment in different scenarios. This design allows the effective value of the VRC current to remain stable within the range of 1.01–1.62A (transmission distance of 22–27 cm). By adjusting the geometric transformation state of the VRC, different output currents can be obtained under fixed positions, loads, and input voltages. The designed receiver can meet the differential current requirements of multiple spatial loads, and is insensitive to factors such as load, transmission distance, and rotation angle. This system can reduce the design complexity of charging and power supply systems and effectively promote the application of Wireless Power Transfer (WPT) in the field of Internet of Things devices.

Design and Optimization of a Planar Omnidirectional Wireless Power Transfer System for Consumer Electronics

Design and Optimization of a Planar Omnidirectional Wireless Power Transfer System for Consumer Electronics

Enhancement Method of Weak Transmission Area for Omnidirectional Wireless Power Transfer System

Enhancement Method of Weak Transmission Area for Omnidirectional Wireless Power Transfer System

Omnidirectional Wireless Power Transfer System Using Modified Saddle-Shaped Coil Pair for Implantable Capsule Robots

Omnidirectional Wireless Power Transfer System Using Modified Saddle-Shaped Coil Pair for Implantable Capsule Robots

A Novel Three-Phase Omnidirectional Wireless Power Transfer System With Zero-Switching-Loss Inverter and Cylindrical Transmitter Coil

Aiming at the problems of large switching loss and large output power fluctuation in the existing omnidirectional wireless power transfer (OWPT) system, a novel OWPT system with zero-switching-loss inverter and cylindrical transmitter coil is proposed. By introducing an auxiliary resonant network with simple structure and low-loss on each phase arm of the three-phase inverter, zero-voltage switching (ZVS) turn-ON and zero-current switching (ZCS) turn-OFF within the full power range can be acquired. The switching loss in the main circuit of inverter is reliably eliminated. The transmitter coil is a cylindrical coil composed of the three curved rectangular coils, whose excitation current amplitude is equal and the phase difference is 120°. It can arise a spatial rotating magnetic field around the transmitter coil and provide an omnidirectional energy transmission channel. The operating principle of soft-switching is analyzed in detail, and the design rules of soft-switching in full power range and the parameter design method of coupler to reduce the fluctuation of output power are given. Ultimately, an experimental prototype is used to verify the feasibility of the proposed OWPT system. The experimental results indicate that the system output power is retained at 93.4W∼104.7W and transfer efficiency is retained at 71.2%∼78.1% under arbitrary angular misalignment of receiver.

Design and Implementation of an Underwater Spatial Omnidirectional Wireless Power Transfer System

Design and Implementation of an Underwater Spatial Omnidirectional Wireless Power Transfer System

Maximum Power Tracking for Magnetic Field Editing-Based Omnidirectional Wireless Power Transfer

This paper proposes and implements an optimized omnidirectional wireless power transfer (WPT) system using distributed transmitter coils is proposed. Under the consideration of practical WPT applications which involve human safety concerns, such as daily home apparatus or wireless rechargeable medical implants, the proposed system can achieve the shortest charging time within the safe limits of human exposure to radiofrequency electromagnetic energy. Based on the calculation of the magnetic intensity generated by multi-coupling WPT systems, a more processable magnetic threshold model is presented and analyzed based on the common standard. A newly developed optimization model of the transmitter currents and accordant control strategy is designed and presented to realize both maximum power tracking and flux suppression at target positions. The double-resonant circuit topology with LCC compensation is adopted to reach the stable and synchronized transmitter currents. The cross-coupling problem in multi-input WPT systems will be solved as well. Full-range magnitude control is realized with a single controller and direct current power source. The hybrid frequency pacing technique is adopted for lower switching frequency and higher system efficiency under weak coupling operations. Taking practical wireless rechargeable medical implant as the research object, both simulation and experimental results validate the feasibility and the prospect of the proposed system.

Compact and Free-Positioning Omnidirectional Wireless Power Transfer System for Unmanned Aerial Vehicle Charging Applications

Compact design in receiver and misalignment tolerance are two basic considerations for practical applications of wireless power transfer (WPT) in unmanned aerial vehicles (UAVs). To balance these two requirements, a novel magnetic design with the composite interval-acted parallel- & vertical-flux throw, orthogonal two-dimensional flux pick-up, and power-flow summed output is proposed in this letter. The resulting magnetic structure includes a target-shaped transmitter and two quadrature receivers, and the transmitter consists of four annular-type coils which are magnetized in a bipolar mode, making it possible to form a magnetic field with a parallel- and vertical-flux complementary distribution. Moreover, by integrating two orthogonal receiving coils into one receiver, a stable summed output current can supply the UAV onboard load with only a small size receiver. A UAV WPT prototype is established based on the proposal. The results show that the prototype can deliver 325 W with a system efficiency of 86%, and especially the variation of the output current is within ±0.76 A for different landing positions and directions. The overall system efficiency is from 87.3% down to 83.1%.

A Reticulated Planar Transmitter Using a Three-Dimensional Rotating Magnetic Field for Free-Positioning Omnidirectional Wireless Power Transfer

This article proposes a free-positioning omnidirectional wireless power transfer (WPT) system with a reticulated planar transmitter, which enables multiple receivers to be powered simultaneously in arbitrary positions and orientations. The reticulated planar transmitter is equipped with four interleaved and overlapped meander coils, thus, a three-dimensional (3-D) rotating magnetic field is generated with the designed excitation current. Therefore, only a planar single-coil (such as a loop-type coil) is required to realize free-positioning omnidirectional WPT. According to the theoretical modeling of the magnetic field, the excitation current that can generate a 3-D rotating magnetic field is given. To obtain a uniform and strong magnetic field distribution, the transmitter grid width is optimized. Furthermore, an excitation current modulation strategy based on phase-shift control is presented to regulate the amplitude of the excitation current. The experimental results show that the output power is greater than 13.1 W no matter how the center of the receiver moves or rotates freely within 400 × 400 mm. When five receivers are powered simultaneously in different positions and orientations, 82.5 W total output power and 55.6% efficiency can be achieved. The experimental results demonstrate that free-positioning omnidirectional WPT can be realized with only planar single-coil receivers by using the proposed reticulated planar transmitter and its excitation current modulation strategy.

High-Efficiency Omnidirectional Wireless Power Transfer System

To achieve omnidirectional wireless power transfer (WPT), it is crucial to tune the direction of the total magnetic field from the transmitter (Tx) coils toward the receiver coil (Rx) that can be placed at different positions with respect to Tx. Several methods, such as amplitude modulation, phase-shifting, and frequency modulation, have been proposed to vary the Tx currents, depending on the angular position of Rx, but complex sensing and feedback control systems are required. In this article, we propose an efficient omnidirectional WPT system that is capable of self-tuning the power flow without any feedback from the Rx-side. It only requires a simple Tx current switching rather than complex feedback control system for detecting the Rx position. The proposed system consists of three orthogonal transmitter–repeater (Tx-Rp) channels that deliver power to Rx. In this configuration, the Tx currents are proportional to the mutual coupling between the Rp and Rx in the same channel, which ensures the self-tuning of the optimal power flow through channels. Both theoretical and experimental studies are performed to validate the proposed method. The prototype of the proposed approach enables the Rx to harvest power with almost uniform high efficiency (about 90%) regardless of its angular position.

Self-Tuning Omnidirectional Wireless Power Transfer Using Double-Toroidal Helix Coils

In this article, we suggest and study a novel omnidirectional wireless power transfer (WPT) system based on unusual double-toroidal helix coils. The suggested antenna is a double-helix coil wounded around a torus. It creates two mutually orthogonal magnetic fields. One is toroidal and confined inside the torus, and another one is poloidal and is distributed outside it. The intensities of these two fields can be independently tuned via the geometry of the turns. The coupling coefficients are tailored to ensure high efficiency regardless of the receiver position and orientation, without active circuitry for tuning or control. This topology provides self-tuning functionality which is achieved when the coupling between the transmitter and receiver is minimized while the coupling in the pairs transmitter–repeater and repeater–receiver is strong. The system consists of three transmitter–repeater pairs orthogonal to each other, ensuring omnidirectional functionality. Experimental results confirm self-tunability and high efficiency for any position and orientation of receivers. The proposed double-helix antenna is applicable to different WPT applications where the coupling/decoupling between coils can be freely controlled.

Power stability analysis of three-phase omnidirectional wireless power transfer system based on tripolar pad

Power stability analysis of three-phase omnidirectional wireless power transfer system based on tripolar pad

Planar Omnidirectional Wireless Power Transfer System Based on Novel Metasurface

In this article, we propose a novel metasurface-basedmagnetic coupling resonant wireless power transfer (MCR-WPT) system to realize planar omnidirectional WPT at a mid-range distance. The resonator devices—dielectric-constant disks or planar helixes—are located on both sides of the metasurface, which comprises conducting wires placed in a planar sunburst pattern. Transmission efficiency of >40% is achieved on a circular plane with a diameter of ∼40 cm. In addition, the transfer efficiency is insensitive to the placement of a human hand near the proposed MCR-WPT system. The maximum permissible input powers for the coil and dielectric resonator versions of the proposed MCR-WPT system are 0.83 and 2.56 W, respectively, in compliance with the limit prescribed in the International Commission of Non-Ionizing Radiation Protection guidelines. The proposed design may help realize many potential WPT applications, especially for the desktop wireless charging of household devices, such as mobile phones, tablets, and LED desk lamps.

A Tripolar Plane-Type Transmitter for Three-Dimensional Omnidirectional Wireless Power Transfer

This article proposes a tripolar plane-type (TPT) transmitter enabling three-dimensional (3-D) omnidirectional wireless power transfer (WPT) for consumer electronics, such as mobile phones and tablet computers. The proposed TPT transmitter is a 2-D plan-type structure, but it shows a 3-D omnidirectional power transmitting capability. This structure consists of two crossed bipolar coils and a unipolar circular coil, and the three coils are mutually decoupled naturally. By calculating the magnetic field distribution generated by the TPT transmitter, a 3-D omnidirectional magnetic field can be obtained. Then, a detailed circuit topology based on the inductor-capacitor-capacitor-series compensation networks and full-bridge inverters with phase-shift control is modeled and analyzed. On this base, an excitation current vector modulation strategy based on a targeting magnetic field is designed, which can improve and stabilize the system output power and efficiency. Finally, an experimental prototype is set up to verify the 3-D omnidirectional power transmitting capability of the proposed TPT transmitter and the effectiveness of the designed current vector modulation strategy. Besides, the superiority of the proposed 3-D omnidirectional WPT system is verified by comparison with other methodologies. The experimental results show that the system output power and efficiency are maintained at 61.4–80.6W and 80.7%–85.2% under arbitrary angular misalignment of the receiver.

Magnetic Field Analysis and Excitation Currents Optimization for an Omnidirectional WPT System Based on Three-Phase Tubular Coils

This article proposes an omnidirectional wireless power transfer system for powering up electronic devices inside a tubular structure, which has good received voltage stability (RVS) no matter how the receiving coil self-rotates on its own axis or revolves around the <i>z</i>-axis. Three-phase tubular coils are taken as the transmitter at the primary side, and a circular coil works as the receiver at the secondary side. Based on a three-phase half-bridge inverter and inductor capacitor capacitor-series (LCC-S) compensated topology, the expression of the received voltage is derived. To achieve the best RVS, the rotating magnetic field of the transmitter is modeled theoretically, and the essence of the RVS under angular misalignment of the receiver is analyzed. The phase difference of excitation currents is optimized to achieve the best RVS under two typical connection types of the transmitter. The finite-element method simulations are conducted to obtain the magnetic field distribution and the relationship between the received voltage and rotation angle. Finally, the experimental results show that the received voltage pulsation can be efficiently reduced within &#x00B1;15.6&#x0025; under arbitrary angular misalignment of the receiver.

Load Detection and Power Flow Control Algorithm For an Omnidirectional Wireless Power Transfer System

This article presents a control scheme for an omnidirectional wireless power transfer system. A system architecture is proposed to implement the current amplitude control. To focus power transfer towards targeted loads, a smart detection algorithm for identifying the positioning and orientation of receiver devices based on the input power information is presented. The system efficiency is further improved by a maximum efficiency point tracking function. A novel power flow control with a load combination strategy to charge multiple loads simultaneously is explained. Finally, the proposed control scheme is successfully applied to an example 6.78 MHz omnidirectional wireless charging bowl system. The experimental results confirm the accuracy of the load detection algorithm and validate the power flow control strategy.

Resonant Network Design Method to Reduce Influence of Mutual Inductance between Receivers in Multi-Output Omnidirectional Wireless Power Transfer Systems

Many studies have been conducted on multi-output systems that transfer power to multiple receivers in conventional planar-type wireless power transfer (WPT) systems; however, few studies and analyses have taken into account the mutual inductance between receivers in multi-output omnidirectional WPT systems. In this paper, the correlation between the mutual inductance between receivers and the power transfer efficiency (PTE) in a multi-output omnidirectional WPT system is analyzed, and a limitation in terms of a reduction in the PTE with an increase in the influence of the mutual inductance between the receivers is presented. To solve this problem, a resonant network design method is proposed to reduce the influence of mutual inductance between receivers, and appropriate canceling capacitor values are selected using the weighted sum method among multi-objective optimization methods. The proposed method is through simulations and experiments, and it presents the potential for improvement in the problems that occur when transferring power to multiple receivers.

LCCL-LC Resonant Converter and Its Soft Switching Realization for Omnidirectional Wireless Power Transfer Systems

Recently, omnidirectional wireless power transfer (WPT) systems have been studied intensely, due to their improved flexibility as compared to their planar counterparts. The LCCL-LC resonant converter topology is selected due to its current source characteristics in this article. The system frequency is pushed to megahertz (MHz) to increase the spatial charging freedom. In a megahertz WPT system, the reactance of the full bridge rectifier can no longer be neglected; therefore, an analytical model of the full bridge rectifier input impedance is built. Furthermore, zero-voltage switching (ZVS) of the switching devices is essential in reducing the switching loss and noise in a megahertz system. A design methodology of the LCCL-LC circuit is proposed to achieve the ZVS operation in the case of one transmitter and one receiver. Then, the ZVS analysis is extended to the scenario of multiple transmitter coils and one receiver coil. Finally, a 6.78-MHz wireless charging system is built according to the proposed design methodology. Experimental results validate the accuracy of the ZVS analysis, and the ZVS operation is well achieved under different coupling and load conditions. The peak system efficiency of 82% at 5-W output power is achieved.

Omnidirectional wireless power transfer system with a multidirectional receiver inside a cubic transmitter

Omnidirectional wireless power transfer system with a multidirectional receiver inside a cubic transmitter