With the rapid development of ultra high voltage direct current(DC) power transmission technology, the stability of valve base electronics (VBE) device is crucial for ensuring the reliability and efficiency of DC power transmission. The defects in VBE device circuit boards, such as short circuits and failed components, directly affect the system stability. However, the existing detection methods including manual microscopic inspection and automatic detection algorithms are often limited by their low efficiency and insufficient accuracy. In this paper, an automatic visual inspection method based on point pattern matching is proposed to address these challenges. This method significantly improves its detection accuracy and efficiency by generating point patterns that represent key areas and further matching them, which is particularly suitable for rapid quality control on production lines. Experimental validation shows that the proposed method significantly outperforms the traditional methods in terms of detection speed and accuracy, providing an effective technical solution for improving the quality of DC power transmission equipment and demonstrating important practical value.

At present, multi-level three-phase voltage source inverters are widely applied in high-voltage and high-power electronic equipment. To solve the problem of DC-side capacitor voltage imbalance during the operation of the traditional three-phase voltage source inverter, the inverter structure is optimized in this paper based on the space vector modulation switch DC power supply. The equivalent model of a multi-level three-phase voltage source inverter is established, the space vector modulation algorithm of the 60° coordinate is used to realize the space vector modulation, and the capacitor voltage balance algorithm is used to fully take into account the switching sequence between different vectors, thus realizing the capacitor current balance. Experimental results show that compared with the traditional method, the proposed method can modulate the multi-level three-phase voltage source inverter, the output line voltage waveform distortion rate is 0.18%, and the voltage fluctuation at the capacitor point can be controlled within 3 V, indicating that this method is superior to the comparison method and has a better application performance.

Accurately obtaining the electromagnetic characteristics of high-voltage and high-power switching devices is crucial for predicting the electromagnetic interference in a system in which the devices are located. Research is focused on an equivalent method of switch waveforms for analyzing the electromagnetic characteristics of high-voltage and high-power switching devices. Aimed at the problem that the existing equivalent waveforms are too ideal to reflect the complex spectral components in the switching transients of devices, an analytical model for the electromagnetic characteristics of devices considering their switching processes is proposed. Starting from the time-domain analytical formula for the analytical model and based on the Fourier transform theory, the frequency-domain analytical formula for the analytical model is derived, and the spectral envelope characteristic parameters are analyzed to obtain the spectral characteristics of the analytical model. The theoretical analysis was verified by using the measured switching waveforms of Si IGBT and SiC MOSFET devices.

The thermal resistance model of a thyristor converter valve considering its water-cooling circuit is estab-lished by combining the mechanism of a thyristor connected in series with the water-cooling circuit, which can calculate the water temperature at the inlet of each heat sink, as well as the junction temperature of each thyristor accordingly. This model is used to calculate the thermal resistance of each component in the converter valve in an example, and a steady-state thermal resistance model is built to calculate the junction temperature of the thyristor. Calculation results show that the maximum calculation error of thyristor junction temperature can reach 10.81% when considering the differ-ence of coolant temperature in the water-cooling circuit.

The power control mechanism of cascaded island microgrids (MGs) composed of dispatchable and non-dis-patchable distributed generations (DGs) is complex, and the voltage and frequency regulation is difficult. Aimed at these problems, a novel decentralized master-slave power distribution control method is proposed in this paper to realize the voltage and frequency regulation and power distribution of the cascaded island MGs including second-class DGs. The control methods for master and slave DGs are designed, respectively. The master DG is responsible for adjusting the fre-quency and voltage of MG. Meanwhile, the slave DGs in MPPT mode can run under certain bus voltage, which can max-imally use the output power from non-dispatchable DGs and perform automatic power reduction under the light load condition, thereby effectively guaranteeing the safety and stability of the system. Finally, the effectiveness of the pro-posed method is verified by simulation and experimental results.

Aimed at the problem that the control modes of interconnecting power converters (IPCs) are complicated to assign and difficult to control when different types of power grids are connected, a novel grid-forming(GFM) control method for IPCs that interconnect high voltage direct current (HVDC) and high voltage alternating current (HVAC) sub-grids is proposed. This method uses modular multilevel converters (MMCs) to control AC and DC terminals simultaneously. In addition, two dual-port GFM MMC control strategies are put forward. Finally, a simulation comparison between single-port GFM control and the proposed two-port GFM control is performed. Results show that compared with the single-port GFM control, the two-port GFM control method is more flexible to emergencies(i.e., line and generator outage), and there is no need to choose the control mode of GFM or grid-following(GFL) for IPC ports in the power grid.

A rapid solution method for the thyristor electro-thermal coupling model based on the conjugate gradient method is developed to address the limitations of traditional solution techniques in terms of processing efficiency and computational cost. By optimizing the iteration process and convergence criteria, the solution efficiency and accuracy are significantly improved. A novel parameter selection strategy is introduced to automatically adjust the algorithm's iteration step size, thus accelerating the convergence speed and reducing the computational resource consumption. Compared with the traditional solution methods, the optimization approach achieves an average reduction of 10% in solution time and an 8% increase in solution accuracy. This progress demonstrates the effectiveness of the adaptive conjugate gradient method in the rapid solution of electro-thermal coupling models, providing an efficient and reliable computational tool for the thermal management of power electronic devices. The proposed method exhibits significant efficiency improvement and good accuracy under various test conditions, offering an innovative solution for efficiently solving the thyristor electro-thermal coupling models. This method is also of practical significance for related research in the field of power electronics.

As the service environment of power semiconductor devices becomes more and more severe, the third-generation semiconductor represented by silicon carbide (SiC) has become the mainstream of industry applications owing to its excellent high-temperature performance. However, the lack of bounding materials which not only match with SiC chips but also have a low cost and a high melting point has become a bottleneck in the development of the industry. Cu-Sn intermetallic compounds (IMCs) are considered to be ideal bounding materials for SiC chips because of their low cost, good conductivity and characteristics that meet the requirements of low-temperature bonding and high-temperature service. Aimed at the power semiconductor device packaging, the preparation and reliability of Cu-Sn full IMC joints at home and abroad in recent years are analyzed and reviewed, and the problems to be solved at present and the development trend in the future are discussed.

With the improvement of the integration degree of power modules, the optimization of their heat transfer structures has become a focus in the development. The topology optimization(TO) can maximize the cooling performance by transforming the morphology and structure of heat sinks, thus receiving extensive attention. However, in the TO process, the temperature distribution of modules and heat sinks needs to be calculated in each iteration step, consuming a large amount of computing resource and calculation time. To accelerate the TO process of traditional heat sinks, a fast iterative method combining neural network (NN) synchronous learning and the traditional solid isotropic material with penalization (SIMP)-based TO methods is put forward. First, an NN prediction model based on the encoder-decoder structure is constructed, which can iteratively evolve the shape of heat sinks to achieve a fast prediction of optimized structures. Second, the NN model is integrated into the TO process of the heat sink based on the SIMP method, and the NN is trained synchronously using the intermediate morphology obtained in the iteration process. Finally, aimed at the single-chip and dual-chip modules, the results obtained by the new method and traditional iterative methods are compared to validate the accuracy and rapidity of the proposed NN synchronous leaning method.

As electronic devices continue to miniaturize and integrate, thermal simulation has become a critical factor during the design phase. The conventional finite element method(FEM) used for the thermal simulation of electronics packaging modules faces a trade-off between computational efficiency and accuracy, and it also encounters difficulties in handling problems of large deformation and grid distortion, which will cause errors in the results. In this paper, a thermal simulation system for electronics packaging modules based on the smoothed particle hydrodynamics (SPH) algorithm is proposed. The SPH algorithm is based on the meshless Lagrange numerical method, and it resolves the heat conduction equation by discretizing the simulation object into a set of particles, thus accurately predicting the heat conduction and heat dissipation in electronics packaging modules. Since it does not need to generate a large number of micro-meshes, there is no grid distortion. Compared with FEM, the SPH algorithm achieves an accuracy error between 1% and 2%, thereby improving the simulation efficiency by approximately 30 times. Therefore, this algorithm is highly suitable in simulating the thermal behavior of a dynamical system with a complex structure.