This paper proposes an LLC-DAB integrated high-frequency isolated DC-DC converter topology structure to reduce the loss and cost of the DC power distribution system. Furthermore, the complexity and efficiency of the system also can be improved. The proposed converter consists of a DAB converter and two input-parallel-output-parallel half-bridge LLC resonant converters. It provides two DC voltage level buses, namely the HVDC bus and the LVDC bus. Compared with the typical converter topology of the DC power distribution system, the number of power semiconductors of the proposed converter topology is reduced by sharing the power semiconductors of the DAB converter and LLC resonant converter. As a result, with the number of power semiconductors decreasing, the cost and loss of the system are reduced. Moreover, the proposed converter can control the flow direction of power conversion and supply power to the loads. The single-phase-shift modulation method is adopted for the DAB converter, and two LLC resonant converters operate as the DC transformer under resonant frequency with open-loop control. The operation principles and characteristics of the proposed converter are discussed. Finally, the simulation is carried out and an experimental prototype is developed to verify the effectiveness of the proposed topology.

Compared with traditional remoting image, there is a large amount of spectral information in the hyperspectral image (HSI), which makes HSI better reflect the actual condition of surface features. However, due to the limitations of imaging conditions, HSI tends to have a lower spatial resolution. In order to overcome this issue, we propose a spectral-spatial attention-based U-Net named SSAU-Net for HSI and multispectral image (MSI) fusion. The SSAU-Net constructs a spectral-spatial attention module by a coordinate-attention (CA) module and an efficient pyramid split attention (ESPA) module, which can enhance the image's spectral information and spatial information. Meanwhile, the proposed network fully extracts the shallow and deep features of the images, and finally generates high-resolution (HR) hyperspectral images. Compared with state-of-the-art HSI-MSI fusion methods, the experimental results verify that the proposed method has a better subjective and objective fusion effect.

A shell-type medium frequency transformer (MFT) using amorphous alloy material is designed for high-power electronic applications. The optimal area product design method is adopted to design an MFT, which maximizes the high efficiency and power density, minimizes the loss and volume, and meets the limitations of insulation and temperature rise. Then, a 20 kVA/10 kHz MFT is designed. To ensure the rationality of the MFT design, the magnetic properties of the amorphous alloy material are measured, and finite element simulations are carried out based on measured magnetic properties. The magnetic flux density, loss, and temperature rise of the designed MFT are analyzed. Finally, a 20 kVA/10 kHz MFT prototype is fabricated, and experimental tests are carried out. The loss and temperature rise of the MFT prototype are within reason, which verifies the effectiveness of the proposed scheme.

In order to solve the problems of poor thermal stability and high frequency noise of transformer in traditional DC-DC converter, the medium frequency transformer in isolated DC-DC converter is designed and studied, which adopts 0.15 mm ultra-thin silicon steel sheet. Firstly, the magnetism of ultra-thin silicon steel is measured by using singlepiece silicon steel sheet measuring device, and the B-H curves and B-P curves at different frequencies are given. According to the magnetic measurement results, the electromagnetic scheme of three port medium frequency transformer is designed by AP method and applied the particle swarm algorithm to further design under the constraint of loss minimization. Secondly the three-winding transformer of DC-DC converter is optimized and simulated. The magnetic flux density, loss, temperature field distribution, output voltage and current waveform of the transformer under different working conditions are given. Finally, the 20 kW DC-DC converter was manufactured and the magnetic characteristics of the medium frequency transformer were experimented to verify the correctness of the proposed scheme.

This paper presents the performance of vector modulation technology in the open-winding permanent magnet synchronous motor (OW-PMSM) considering the unity power factor control. And a topology structure is proposed to optimize the fault tolerance of inverter. Matlab software and Maxwell software collaborative simulation are supplied to obtain the reactive power, speed, terminal voltage, electromagnetic torque etc. under normal and fault status. Finally, the simulation results of an open-winding permanent magnet synchronous motor are verified by the experimental results.