Search

This paper presents the machine learning-based detection of foreign metal object for the wireless power transfer device including differential coils. To test the proposed method, the differential voltages are computed using finite element method for about 1500 cases with and without an aluminum cylinder at driving frequency of 85 kHz considering misalignment between the primal and secondary coils. It has been shown that gradient boosting decision tree and random forests classifier have the accuracy over 90% when input voltages and differential voltages are inputted together.

This article proposes a novel 2.5-D multi-phase topology optimization method using a Gaussian basis function for permanent magnet motors. The design region in the rotor was sliced into cylindrical layers; the 2-D topology optimization was performed for each layer such that the average torque was maximized, while the torque ripple was suppressed to the maximum possible extent. The proposed topology optimization could determine the rotor core and magnet shapes, as well as the magnetization direction. It was shown that the optimized 2.5-D topology optimization led to better torque performance when compared to conventional 2-D optimizations.

This study proposes a method for wireless power transfer systems to identify the existence of foreign metal objects and simultaneously predict the misalignment distance between the primary and secondary coils. The proposed method is based on a neural network (NN) trained using electromagnetic field simulations. The training data for the NN consist of the differential voltages in the detection coils, together with the input voltage of the primary coil. Although the metallic objects and coil misalignment induce confusing voltages, the trained NN exhibits over 90% accuracy for the validation dataset, and mean prediction errors of less than 1 mm for the misalignment distance and ground clearance variance.

In this study, we propose a fast topology optimization (TO) method based on a deep neural network (DNN) that predicts the current-dependent motor torque characteristics using its cross-sectional image. The trained DNN is shown to provide the current condition that provides the maximum torque under the assumed motor control method. The proposed method helps perform TO with a reduced number of field computations while maintaining a high search capability.

This article proposes a novel analysis method for the losses in a litz wire considering the circulating and eddy currents. In the proposed method, the macroscopic complex permeability is introduced to evaluate the eddy current loss owing to the proximity effect. Homogenization-based finite element analysis using the macroscopic complex permeability can effectively compute the proximity effect loss. The loss owing to the circulating currents is evaluated by solving the corresponding circuit equation. It is shown that the eddy current loss is dominant for the solenoidal and spiral coils without magnetic cores because of the uniform magnetic field distribution along the wire. Moreover, the magnetic reactors in which the circulating current loss cannot be ignored are analyzed using the proposed method. It is shown that the losses computed by the proposed method agree well with the measured results.

This article proposes a novel topology optimization method using the Gabor filter, which is widely used in the field of image processing. The proposed method is applied to the optimization of a synchronous reluctance motor; its average torque is maximized, and simultaneously, the torque ripple is minimized. It is shown that the proposed method results in a motor with thin layer-shaped flux barriers, which achieves a better torque performance in comparison with a conventional model and a motor optimized using normalized Gaussian network (NGnet).

In this paper, the multi-objective topology optimizations of wireless power transfer (WPT) devices with two different coil geometries are proposed for obtaining the designs with good balance between transfer efficiency and safety. For this purpose, the proposed method adopts the normalized Gaussian network (NGnet) and Non-dominated Sorting Genetic Algorithm II (NSGA-II). In addition, the optimization under the different constraint on ferrite volume is carried out to verify its influence on optimization results. It has been shown that the proposed method successfully provides the Pareto solution to the design problem of the WPT device.

This paper presents three-dimensional topology optimization of magnetic cores for wireless power transfer with double-sided winding coils. In this optimization, the magnetic core shape is represented by the linear combination of the normalized Gaussian functions. The core shape is optimized so that the coupling coefficient between the transmitting and receiving coils is maximized. Moreover, robustness against misalignment between the coils is taken into account in the optimization. It is found that the optimized core shape effectively increases the net magnetic flux interlinked with the receiving coil, and outperforms the conventional core shapes.

This paper presents the topology optimization of the magnetic core for a wireless power transfer (WPT) device. In this optimization, the coil and magnetic-core shapes for WPT are represented by the Gaussian basis functions. They are sequentially optimized using the genetic algorithm and 3-D finite-element analysis so that the coupling coefficient of the WPT device is maximized. Moreover, a robust optimization method is proposed to keep the interlinkage flux as large as possible against misalignment in the coils. It is shown by the computational and experimental results that the optimized device outperforms the conventional devices.

A new method is introduced to evaluate the macroscopic permeability of a litz wire which is composed of stranded conductors. In this method, an integral equation is solved for the complex magnetization in the litz wire generated due to the proximity effect. The macroscopic permeability computed from the magnetization is used in the homogenization-based finite-element analysis of eddy currents in a litz-wire coil. It is shown that the wire twist has a little effect on the complex permeability.

In this work, the multi-turn coil used in a wireless power transfer (WPT) device is modeled as a uniform material using the homogenization method to consider the proximity effect. By fitting the coil impedance to the numerical results, the Cauer equivalent circuit of the multi-turn coil is synthesized for design and optimization of the power circuits in the WPT device. It is shown that the results obtained from the equivalent circuit and measurement are in good agreement. Moreover, the impedance of a flat WPT coil composed of a Litz wire is shown to be accurately evaluated by the proposed method when contribution of capacitance is negligible.