The underwater wireless power transfer (UWPT) technology provides a feasible way to solve the problems of the traditional power supply method of the autonomous underwater vehicle (AUV). The magnetic coupler is the most essential component in the wireless power transfer system. Its configuration determines its applicable scenarios, and its parameter design and optimization will directly affect the system's overall output power and efficiency. In this article, an arc-shaped underwater wireless power transfer magnetic coupler is proposed, which is suitable for AUV's curved shell. Especially, the proposed novel magnetic coupler utilizes Fe-based nanocrystalline alloy soft magnetic material as the magnetic core. Both volume and weight of the receiver are reduced compared with the traditional Mn-Zn ferrite material. Fe-based nanocrystalline alloy material provides a novel design idea for the magnetic coupler on electrical equipment with special-shaped shell due to its flexibility. A prototype of the UWPT system for 320 mm diameter AUV is built, and it can transfer 3 kW power in the experiment with a dc–dc efficiency of 91.9% at the forward maximum output power point. Compared with the structure with ferrite core, the volume of the proposed structure is reduced by 41.1%, and the weight is reduced by 42.6%, so that the expected effect has been achieved.

This paper presents a multiphase permanent magnet synchronous motor (PMSM) for the more electric aircraft propulsion. The stator winding of the motor is composed of multiple sets of multiphase windings with different parameters. The purpose of the motor design is to modify the distribution of the high efficiency area of the motor by reasonably matching the winding parameters of each set, thereby making the motor more suitable for the working condition of more electric aircraft and improving the working efficiency of the motor. This paper analyzes the selection principle of slot-pole combination and the influence that asymmetric windings have on the motor magnetic field. Three basic matching modes are proposed: equal torque matching, equal power matching and equal speed matching. The motor model is established, with the external characteristics, efficiency and dynamic response of different matching modes being compared and analyzed. The results show that equal torque matching and equal speed matching can reduce the total loss of the motor in a complete flight working condition, whereas equal power matching is not suitable for more electric aircraft.

The multiphase receiver for more steady output is proposed in this paper. The conventional power supply rail with multipole such as I-type has a main drawback: the induced voltage of the double-D coil of receiver has a sinusoidal fluctuation. The multiphase receivers are proposed to solve the problem. The fluctuation factor, effective value of induced voltage and mutual inductance, cost and loss of different numbers of phase in different connection modes are analyzed and compared. The applicable conditions of different types are given. The structural size of single-phase coil is optimized to achieve larger coupling coefficient. The influence of distance between phases on fluctuation factor and induced voltage are calculated and the design principle of the distance between phases is determined. Design guideline is proposed including the constraints of installation environment and the distribution of different phases. The structural size of single-phase coil and the distance between phases are optimized to improve the coupling coefficient and reduce cost, loss and voltage level of resonator. A four-phase receiver of 10kW DWC system is designed and constructed. In the dynamic 10kW experiment, the fluctuation factor is reduced to 0.146 from 0.3 of two-phase receiver and 1.0 of single-phase receiver.

A novel magnetic coupling mechanism with steady output and low cost is proposed in this paper. It composed of n-type power supply rail and dual-phase coil receiver. The conventional I-type power supply rail has advantages of narrow width, large lateral tolerance and low electromagnetic field (EMF) radiation which are suitable for dynamic wireless charging. The double-D (DD) coil is used as the receiver which is also seen as single-phase coil receiver. However the induced voltage of the receiver has a sinusoidal variation with large fluctuation and has zero point along driving direction. The dual-phase coil receiver is proposed to solve this issue and enhance the output power simultaneously. Compared with I-type power supply rail, the n-type power supply rail is proposed to improve the utilization of the magnetic core and reduce the construction cost which are crucial for commercialization of dynamic wireless charging of electric vehicles in the future. The advantages of I-type are also preserved. The enhanced output power of dual-phase coil receiver is verified by circuit analysis. We focus on the influence of the structure size by finite element analysis (FEA) simulation and the design method of structural parameters is proposed to achieve larger lateral tolerance, greater coupling performance and lower cost. The structure size is optimized and the analyses are verified by a 10 kW prototype system. The fluctuation of induce voltage has been reduced from 100% to 30%. When the lateral displacement of the receiver is 30 cm at airgap of 20 cm, induced voltage drops by only 30%. The EMF is also measured to ensure safety on the environment.

To address the problem of high-frequency ac loss of hairpin winding, a hybrid transposed hairpin winding (HTHW) scheme, which combines flat wire and litz wire, is proposed. The HTHW can effectively reduce the high-frequency ac loss, while maintaining a relatively high slot fill factor. In this article, the ac loss generation mechanism under high-frequency excitation is first analyzed. Then, based on the field-circuit-coupled finite element method, the current density distribution, and ac loss of hairpin winding with different transposed topologies are calculated and compared. Finally, an experimental platform enabling direct measurement of hairpin winding loss is built to verify the simulation. The simulation and experimental results show that the ac loss of the proposed HTHW is much lower than that of the traditional hairpin winding, for medium to high running frequency. In our case, the ac and dc resistance ratio of the presented HTHW is 2.12 at the frequency of 1200 Hz, contrasting that of the ratio of traditional hairpin winding, which is 10.2.

This article proposes an interturn short-circuit fault diagnosis method for permanent magnet synchronous machines for electric vehicles based on search coils (SC) with a unique structure. In this proposed structure, the SCs are uniformly wound in the main flux direction of each phase, and the number of SCs is twice the number of phases, resulting in significant cost savings. Based on this structure, a novel fault feature based on the negative-sequence components of the second carrier frequency sideband harmonics in the voltage signal of the SC is proposed. As a result, this fault characteristic frequency component is not only more obvious than the fundamental component used in the traditional SCs method but also can be transformed to a dc indicator by two coordinate transformations, which is conducive to online implementation in both stationary and nonstationary conditions. Finally, experiments are presented to verify the proposed diagnosis strategy.