Efficiency of the Wireless Power Transfer System with Planar Coils in the Periodic and Aperiodic Systems

This article presents the results of the proposed numerical and analytical analysis of the Wireless Power Transfer System (WPT). The system consists of a transmitting surface and a receiving surface, where each of them is composed of planar spiral coils. Two WPT systems were analysed (periodic and aperiodic) considering two types of coils (circular and square). In the aperiodic system, the adjacent coils were wound in the opposite direction. The influence of the type of coils, the winding direction, the number of turns, and the distance between the coils on the efficiency of the WPT system was compared. In periodic models, higher efficiency was obtained with circular rather than square coils. The results obtained with both proposed methods were consistent, which confirmed the correctness of the adopted assumptions. In aperiodic models, for a smaller radius of the coil, the efficiency of the system was higher in the square coil models than in the circular coil models. On the other hand, with a larger radius of the coil, the efficiency of the system was comparable regardless of the coil type. When comparing both systems (periodic and aperiodic), for both circular and square coils, aperiodic models show higher efficiency values (the difference is even 57%). The proposed system can be used for simultaneous charging of many sensors (located in, e.g., walls, floors).

Magnetic Coupler Optimization for Inductive Power Transfer System of Unmanned Aerial Vehicles

Unmanned aerial vehicles (UAVs) have been widely used in military and civilian applications. However, the insufficient cruising range restricts the development of UAVs due to the limitation of their battery. Inductive power transfer (IPT) is an effective way to charge the battery and solve this problem. Magnetic coupler is a key component of the IPT system, which greatly affects the power transfer and efficiency of the IPT. This paper proposes a new magnetic coupler with vertical spiral coils and ferrite PQI cores for the IPT system of UAVs, which can enhance the magnetic coupling and improve the performance of the IPT system. Finite element simulations are used to investigate the magnetic field distribution and coupling capability of the proposed magnetic coupler. In addition, an experimental platform is built to prove the validity of the IPT system using the proposed magnetic coupler. The results show that the coupling coefficient can reach 0.98, and the system transfer efficiency is 89.27% with an output power of 93 W. The IPT system also has a perfect misalignment tolerance and can achieve a stable output power.

Optimization and Analysis of Multilayer Planar Spiral Coils for the Application of Magnetic Resonance Wireless Power Transfer to Wearable Devices

In this study, small multilayer planar spiral coils were analyzed and optimized to wirelessly charge an in-ear wearable bio-signal monitoring device in a wine-glass-shaped transmitter (Tx) based on magnetic resonance wireless power transfer (MR-WPT). For analysis of these coils, a volume filament model (VFM) was used, and an equivalent circuit formulation for the VFM was proposed. The proposed method was applied to design effective multilayer coils with a diameter and height of 6 and 3.8 mm, respectively, in the wearable device. For the coils, a printed circuit board having a 0.6 mm thick dielectric substrate and a 2 oz thick copper metal was used. Moreover, the coils on each layer were connected in series. The dimensions of the double-, four-, and eight-layer coils were optimized for the maximum quality factor (Q-factor) and coupling efficiency. The operating frequency was 6.78 MHz. The optimal dimensions for the maximum Q-factor varied depending on the number of coil layers, pattern width, and turn number. For verification, the designed coils were fabricated and measured. For the four-layer coil, the coupling efficiency and Q-factor using the measured resistance and mutual inductance were 58.1% and 32.19, respectively. Calculations showed that the maximum Q-factor for the four-layer coil was 40.8 and the maximum coupling efficiency was 60.1%. The calculations and measurement were in good agreement. Finally, the entire system of the in-ear wearable bio-signal monitoring device, comprising a wine-glass-shaped transmitter, the designed receiving coil, and a monitoring circuit, was fabricated. The measured dc-dc efficiency of the MR-WPT system was 16.08%.

Integrating Electromagnetic Acoustic Transducers in a Modular Robotic Gripper for Inspecting Tubular Components

Tubular structures are critical components in infrastructure such as power plants. Throughout their life, they are subjected to extreme conditions or suffer from defects such as corrosion and cracks. Although regular inspection of these components is necessary, such inspection is limited by safety-related risks and limited access for human inspection. Robots can provide a solution for automatic inspection. The main challenge, however, lies in integrating sensors for nondestructive evaluation with robotic platforms. As part of developing a versatile lizard-inspired tube inspector robot, in this study the authors propose to integrate electromagnetic acoustic transducers into a modular robotic gripper for use in automated ultrasonic inspection. In particular, spiral coils with cylindrical magnets are integrated into a novel friction-based gripper to excite Lamb waves in thin cylindrical structures. To evaluate the performance of the integrated sensors, the gripper was attached to a robotic arm manipulator and tested on pipes of different outer diameters. Two sets of tests were carried out on both defect-free pipes and pipes with simulated defects, including surface partial cracking and corrosion. The inspection results indicated that transmitted and received signals could be acquired with an acceptable signal-to-noise ratio in the time domain. Moreover, the simulated defects could be successfully detected using the integrated robotic sensing system.

Inductive power transmission through printed sprial coils for seizure application

This thesis proposes a realistic model for transcutaneous inductive power link for seizure applications using PSCs (Printed Spiral Coils). The benefit of this model is smaller size implanted coil compared to its counterparts while maintaining high loaded system efficiency. The introduced Printed Spiral Coil (PSC) geometric parameters are achieved using MATLAB that searches for the highest efficiency of the inductive coil within the given constraints. The output from the MATLAB simulation is used to created optimum design in AMDSpro tool and is verified. The outer diameter of the implanted coil is introduced to be d₀₂ = 6mm while the simulated efficiency is calculated as η [subscript] sim = 46.67% operating at f [subscript] sim = 2.52MHz for the relative distance of D = 10mm filled with layers of modeled human skull (Outer Compact Layer, Spongiosum, and Inner Compact Layer). The coupling coefficient of the spiral was calculated to be k = 0.69. The implanted PSC is associated with load capacitance and resistance of R [subscript] L = 4.5Ω and C [subscript] L = 95nf.

Inductive power transmission through printed sprial coils for seizure application

This thesis proposes a realistic model for transcutaneous inductive power link for seizure applications using PSCs (Printed Spiral Coils). The benefit of this model is smaller size implanted coil compared to its counterparts while maintaining high loaded system efficiency. The introduced Printed Spiral Coil (PSC) geometric parameters are achieved using MATLAB that searches for the highest efficiency of the inductive coil within the given constraints. The output from the MATLAB simulation is used to created optimum design in AMDSpro tool and is verified. The outer diameter of the implanted coil is introduced to be d₀₂ = 6mm while the simulated efficiency is calculated as η [subscript] sim = 46.67% operating at f [subscript] sim = 2.52MHz for the relative distance of D = 10mm filled with layers of modeled human skull (Outer Compact Layer, Spongiosum, and Inner Compact Layer). The coupling coefficient of the spiral was calculated to be k = 0.69. The implanted PSC is associated with load capacitance and resistance of R [subscript] L = 4.5Ω and C [subscript] L = 95nf.