Misalignment Tolerance Research Articles

Novel Designs of Magnetic Coupled Structure With 360° Rotation Misalignment Tolerance for AUVs’ Wireless Charging System

Novel Designs of Magnetic Coupled Structure With 360° Rotation Misalignment Tolerance for AUVs’ Wireless Charging System

A dual‐excitation inductive power transfer system with decoupled transformer for high misalignment tolerance

AbstractThis study delves into the design and optimization of a 4 kW dual‐excitation inductive power transfer system designed to accommodate large misalignments. The system utilizes a bipolar‐solenoid inductive coupled transformer as its coupling mechanism. Detailed simulation and analysis of this coupling mechanism are conducted. Additionally, the system employs a control strategy aimed at optimizing the coordination between output power and efficiency. This control strategy dynamically adjusts the power of the two transmitters, aiming to enhance system efficiency to the maximum extent possible under favourable coupling conditions. Moreover, it ensures that the system's output power remains at or above the rated value even when coupling conditions deteriorate. During the experiment, the system can optimize the output power and efficiency at the same time by using a suitable control strategy when the coils are misaligned. Meanwhile, the system can achieve a minimum efficiency of 81.5% even when the misalignment distance reaches 300 mm (60% of per transmitting coil size). The system and control strategy proposed in this paper can effectively overcome the deterioration of the output characteristics of the wireless power transfer system when misalignment occurs.

High-efficiency and easy-processing thin-film lithium niobate edge coupler

Fiber-to-chip coupling with ultralow loss and broadband operation wavelength range is essential in the practical applications of thin-film lithium niobate (TFLN) integrated photonic devices. However, the existing edge couplers often require electron beam lithography overlaying and multiple etching processes, which are expensive and complex. In this Letter, we demonstrate an edge coupler that includes only a vertically tapered TFLN waveguide and silicon dioxide cladding. The coupling efficiency between a lensed fiber and an on-chip LN waveguide is down to 1.43 dB/facet, while the 3-dB bandwidth exceeds the range from 1510 to 1630 nm. These edge couplers also show reliable fiber misalignment tolerance. Furthermore, the fabrication complexity is greatly reduced since only a single etching step for the TFLN waveguide is needed. The minimum waveguide width of 1.3 μm guarantees compatibility with i-line photolithography, providing a potential for massive production of TFLN devices.

Novel analysis of alignment error on spherical Fizeau interferometer and uncertainty evaluation of sphericity calibration system based on random ball test

The National Metrology Institute of Japan (NMIJ) has developed a high-precision sphericity calibration system utilizing a Fizeau interferometer and conducted a thorough evaluation of the system's measurement uncertainty. Generally, there are two principal sources of uncertainty in the measurement outcomes when utilizing a spherical Fizeau interferometer. First, the accuracy of the system is significantly influenced by the prior knowledge of the reference sphere surface's absolute profile. To address this, the study established a straightforward yet effective calibration system for the reference sphere surface using a random ball test method. Second, the system's precision is affected by misalignment aberration, which occurs when there is any lateral or longitudinal displacement of the test sphere from the confocal position relative to the reference sphere. This misalignment can introduce both high-order shape errors (misalignment aberrations) and low-order shape errors (alignment errors). Through analytical consideration of an observation coordinate system on the camera plane, this study delves into misalignment aberrations, suggesting that the impact of misalignment should be determined experimentally for each reference sphere unit due to potential imperfections that may be revealed by misalignment. Furthermore, the study proposes that uncertainties related to misalignment aberrations are theoretically confirmed to be smaller than previous studies by conducting an in-depth uncertainty analysis of the misalignment, with a focus on the observation coordinate system on the camera plane. Notably, the research demonstrates that a measurement uncertainty level of λ/100 is achievable, maintaining a broader tolerance for misalignment than previously reported studies. The uncertainty of calibration of the reference sphere unit's absolute profile was 4.2 nm and the uncertainty of sample measurement was determined to be 4.6 nm with misalignment tolerance of ±λ/10. This advancement marks a stride toward improving the accuracy and reliability of sphericity measurements, offering potential for widespread application in precision engineering and metrology.

Multi‐objective optimization of inductive power transfer system with reconfigurable topology for misalignment tolerance

AbstractAt present, most of the analyses or studies about inductive power transfer (IPT) with constant current (CC) output and constant voltage (CV) output are carried out without considering misalignment conditions or different gaps. An IPT system satisfying battery charging demand and anti‐misalignment requirements simultaneously is infrequent. This paper proposes a multi‐objective particle swarm optimization method of IPT reconfigurable topology to realize CC and CV modes at varying resistance conditions and wide coupling ranges. The output characteristics of an inductor–capacitor–capacitor (LCC)–LCC compensation circuit have been explored, and it is found that the secondary‐side compensated capacitors have a greater impact on the output power, which can be used to improve power regulation ability accompanied by coupling varying. Eight optimization compensated parameters of the reconfigurable topology are obtained from the Pareto front to achieve the required CC and CV charging outputs. By switching the compensated capacitors, the selected parameters can make the current and voltage fluctuation less than 9.3% and 7.9%, respectively, during the coupling charging range from 0.3 to 0.22. Moreover, primary zero voltage switching operation is achieved to enable high efficiency. The simulation and the experimental verification are carried out to verify the validity of the proposed method.

A New Magnetic Coupler with High Misalignment Tolerance and Inherent Constant Current–Constant Voltage for Underground Wireless Charging

In an underground inductive power transfer (IPT), it is inevitable to produce the phenomenon of misalignment between the transmitter and the receiver, which will reduce the output current, voltage and output efficiency of the whole IPT system. Aiming to solve this problem, a universal hybrid coupler is proposed, which can still stabilize the output in the expected range and has the ability of anti-misalignment when the X and Z directions are misaligned. The coupler is composed of a BP coupler and Γ type network. The secondary edge of the coupler introduces a Γ network, which decouples the two main coils on the same side of the receiver from the auxiliary coil and reduces the complexity of the system. The coupler can effectively reduce the coupling fluctuation caused by physical movement between the downhole transmitting end and the receiving end, thereby ensuring the stable output of the coupler. As a widely used IPT system, it can access the rest of the circuit topology whose output is independent of the load and achieve misalignment-tolerant output. Finally, based on the proposed hybrid IPT coupler theory, a 500 W misalignment-tolerant coupler prototype was built, and the compensation topologies were configured as series–series (SS) and series/inductance/capacitance/capacitor (S/LCC) structures. When the X and Z direction is misaligned, the constant current and voltage independent of the load can be output by switching the compensation topology. The experimental results are the same as the theoretical analysis.

Design of Docking Interfaces for On-Orbit Assembly of Large Structures in Space

Considering the complexity of on-orbit assembly during space missions and the super-large size of space structures, this paper presents the design for a new type of docking interface with an androgynous body that exhibits a number of advantages, including high connection strength and a compact structure. The androgynous body has a conical guided symmetric design with a symmetry of 90°. The geometric design of the docking surface is described in detail in order to prove its advantages. Structural design was carried out using UG modeling as well as dynamic simulation using Recur Dyn to obtain the displacement coordinate curves of the docking port. The geometry of the docking port’s high docking misalignment tolerance was verified, and misalignment tolerance and lens splicing experiments were also performed. The docking port’s ability to be quickly connected or disconnected within a translation tolerance of 23.5 mm and a tilt tolerance of 24° was verified. This article provides a useful reference for space missions in terms of module docking and on-orbit assembly.

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%.

Analysis and Design of a 6.78 M Wireless Power Transfer System With Strong Misalignment Tolerance Based on Simplified Impedance Trajectory Tracing

Analysis and Design of a 6.78 M Wireless Power Transfer System With Strong Misalignment Tolerance Based on Simplified Impedance Trajectory Tracing

A Parameter Identification and Control Method Based on Compensation Topology With Strong Misalignment Tolerance

A Parameter Identification and Control Method Based on Compensation Topology With Strong Misalignment Tolerance

Enhanced Axial Misalignment Tolerance in a 10-kW Autonomous Underwater Vehicle Wireless Charging System Utilizing a Split Solenoid Coupler

Enhanced Axial Misalignment Tolerance in a 10-kW Autonomous Underwater Vehicle Wireless Charging System Utilizing a Split Solenoid Coupler

A Single-Transmitter Multi-Receiver Wireless Power Transfer System with High Coil Misalignment Tolerance and Variable Power Allocation Ratios

This article proposes a single-transmitter multi-receiver wireless power transfer (STMR-WPT) system, which uses a cross-overlapped bipolar coil as the transmitter and multiple square unipolar coils as the receivers. By using this structure, the magnetic field of the system can be adjusted to accommodate different coil misalignment conditions. In addition, the proposed system uses C-CLCs networks to achieve separate load power allocation. Thus, relay coils, complex multi-frequency transmission channels and multiple independent power supplies can be avoided. A mapping impedance-based circuit model was established to analyze the characteristics of the system, and then a single-frequency power allocation method was presented. Through this method, the STMR-WPT system can achieve load power allocation at any specified ratios under different mutual inductance and load impedance conditions. Finally, an experimental STMR-WPT system was built. The side lengths of the transmitter and receiver coils are 400 mm and 160 mm, respectively. The measurement results indicated that when the lateral or longitudinal coil misalignment varies within the range of 0~200 mm, the coupling coefficient decreases by a maximum of 6% compared to the initial value, and when the angular coil misalignment varies within the range of 0~90 degrees, the coupling coefficient decreases by a maximum of 22% compared to the initial value. In four different power allocation scenarios, the experimental STMR-WPT system successfully achieved the expected power allocation goals.

Extending the design space of minimized VA rating inductive wireless power transfer links operating in restricted sub-resonant frequency region with constant current output

Wireless power transfer systems are typically required to operate under varying geometrical positioning (vertical distance, misalignment) between the transmitter and receiver coils while supporting a load with non-constant characteristics. This creates the need for robust systems that can operate over a range of coupling coefficients under time-varying load. Widespread control methods utilized to support such an operation typically suffer from volt-ampere (VA) over-rating of the inductive wireless power transfer link (IWPTL) transmitter. Sub-resonant frequency control has proven to be an effective solution to this problem, attaining robust operation and minimized transmitter VA rating by utilizing operational frequency as the control variable for system output regulation under above-mentioned constraints. However, allowed operating frequency range is usually restricted in practical applications (e.g. to 79 kHz–90 kHz by SAE J2954 EV charging standard), limiting the misalignment tolerance of sub-resonant control method. Recently, extension of the classical sub-resonant control methodology was proposed in order to overcome this limitation. However, no clear guidelines were given for designing practical IWPTLs operating under extended sub-resonant control. To this end, this work bridges the gap between academical findings and practical applications by establishing generalized guidelines for designing sub-resonant controlled series-series (SS) compensated IWPTL with minimized transmitter VA rating, allowing to maximize misalignment tolerance under given operating frequency and output voltage ranges. The proposed methodology is accurately validated by simulations and experiments, demonstrate close correlation with analytical predictions. Experimental framework reveals that IWPTL operating under extended sub-resonant control methodology attains 50 % increase of tolerable coupling coefficients range compared to a classical system designed to operate under sub-resonant control under identical operating conditions while achieving nearly similar DC-to-DC efficiency.

Broadband and low-reflection mid-infrared grating coupler for a perfectly vertical fiber-chip interface.

Short-wavelength mid-infrared (SWMIR) silicon photonics has gained significant attention due to its applications in sensing, spectroscopy, and communications. A perfectly vertical grating coupler is a valuable packaging technique that is convenient for chip-to-chip optical interconnects and has low risks of mechanical failure during testing. However, SWMIR grating couplers have fewer periods to tailor the diffracted light, hindering the improvement of bandwidths and backreflections. Herein, we demonstrate a perfectly vertical subwavelength grating coupler by using a modified inverse design approach. The device exhibits a coupling efficiency of -5.9 dB with a 1-dB bandwidth of ∼122 nm and a low backreflection of -19.2 dB at 2200 nm wavelengths. Besides, the device also exhibits exceptional spatial fiber misalignment tolerance. The study underscores the effectiveness of the inverse design strategy in subwavelength grating couplers, charting a path to advance the mid-infrared silicon photonic packaging.

Research on collaborative locking strategy for distributed locking system of space manipulator

In this paper, the dynamic interaction between the locking system and the space manipulator is analyzed, and a misalignment tolerance capability analysis method for the distributed locking system of the space manipulator is proposed. Based on the structure and layout characteristics of the locking mechanism, the collision dynamics analysis between the manipulator and the locking system during the locking process is carried out, and the factors for the locking failure caused by the escape of the locking frame on the passive end of the locking mechanism are obtained. Aiming at the factors of escape of the locking frame and improving the misalignment tolerance of the locking system, the locking action matching of the active end of the locking system is carried out, which lays a foundation for the design of a collaborative locking strategy. The collaborative locking strategy model of the locking system was established to match the locking speed of the hook in the locking stage. Using the proposed misalignment tolerance capability analysis method combined with simulation software to simulate the conventional locking strategy and the collaborative locking strategy. By comparing the simulation results, the large misalignment tolerance capability of the collaborative locking strategy is verified.

Enhancing Misalignment Tolerance in Hybrid Wireless Power Transfer System With Integrated Coupler via Frequency Tuning

Enhancing Misalignment Tolerance in Hybrid Wireless Power Transfer System With Integrated Coupler via Frequency Tuning

Dual-Receiver Based Naturally Decoupled Coil Structure With Improved Rotational Misalignment Tolerance for WPT Systems

Dual-Receiver Based Naturally Decoupled Coil Structure With Improved Rotational Misalignment Tolerance for WPT Systems

Misalignment‐tolerant coupling cell of 2‐D modular WPT system for charging area simplified extension

Abstract2‐D modular wireless power transfer (WPT) system needs to have stable output when coil misalignment occurs. In order to improve the misalignment tolerance of the system coupling unit, this article proposes a magnetic coupling structure based on the LCC‐S compensation topology by combining a rectangular coil with two sets of mutually orthogonal solenoidal compensation coils. The rectangular coil is used to receive the vertical magnetic flux, and the two sets of compensating coils are used to receive the magnetic flux in the directions of X‐axis and Y‐axis on the horizontal plane, separately. The receiving side of the 2‐D wireless power transmission array cells cascaded half‐bridge rectifiers to connect each group of coils. This arrangement effectively compensates for the voltage drop of the rectangular coil caused by positional offset in any direction, so that the output voltage of the receiving side remains stable. The article firstly establishes the equivalent circuit model of the proposed design and deduces in detail the relationship equations between the output characteristics of the system and each influence factor. Secondly, the magnetic coupling structure is designed by finite element electromagnetic simulation software, and the total equivalent mutual inductance fluctuation of the proposed design is verified to be within 3.9% over the range of 2‐D transmission array cells. Finally, a 150 W experimental platform is built to verify the misaligment‐tolerant of the proposed design in the range of 2‐D transmission array cells. The experimental results show that the output voltage fluctuation of the proposed design within 4.27% at all directional offsets. Moreover, the stable output performance can be obtained in the case of vertical and rotational misalignment.

A 1 kW, 76% efficiency underwater single‐capacitor coupled WPT system with a 1 m separation distance single‐capacitor coupled

AbstractIn this paper, an underwater single‐capacitor coupled wireless power transmission (USCC‐WPT) system is proposed, which operates at 200 kHz and can transmit 1 kW of power at 1 m in seawater with an efficiency of 76%. The USCC‐WPT system produces no eddy current losses in seawater, and the distance is increased compared to conventional inductive power transfer systems. The system proposed in this paper has a wide range of applications underwater. The load‐independent constant voltage (CV) output and misalignment tolerance properties of the USCC‐WPT system are analyzed and validated by an equivalent circuit model constructed from the stray capacitance. The 1 kW prototype demonstrates the feasibility of the USCC‐WPT system proposed in this paper, while the system can work properly with 50 cm misalignment.

A novel arc‐shaped magnetic coupler with dual‐channel receiver for rotational misalignment tolerance in AUV underwater wireless power transfer systems

AbstractTraditional wet plug charging for autonomous underwater vehicles (AUVs) limits its application. Inductive power transfer (IPT) is an effective solution to this problem. This paper proposes an arc‐shaped magnetic coupler incorporated with solenoid coils to achieve a stable and efficient output against rotational misalignment for charging AUV. The novel magnetic coupler consists of two solenoid coils and an arc‐shaped coil with a reverse winding, guaranteeing a relatively constant total mutual inductance and decoupling from each other. This magnetic coupler has the characteristics of a compact structure, an ultra‐wide coupling range, and a relatively stable equivalent mutual inductance. The experimental IPT prototype can deliver 1.29 kW with a dc–dc efficiency of 93% under the fully aligned case and 1.2 kW with a dc–dc efficiency of 91% under the misaligned case.