Insulated gate bipolar transistors (IGBTs) are the key semiconductor power devices in the systems of power electronics due to the advantages of large capacity, fast switching speed, easy to drive, low on-voltage and high input impedance. Due to the temperature swinging and mismatches of the coefficients of thermal expansion (CTE) of internal materials in IGBT modules, electrical-thermal-mechanical coupling is generated and inevitably results in thermal deformation. This thermal deformation is one of the key factors causing IGBT reliability issues. Therefore, it is of great significance to study the electrical-thermal-mechanical deformation characteristics of IGBT modules.

Switching mechanical wave (SMW) effect has attracted extensive attention over the past few years owing to its broad application prospects in condition monitoring for insulated gate bipolar transistor (IGBT) devices. The latest research suggests that the method of directly measuring the mechanical vibration signal on IGBT bare die by laser vibrometer is of great significance and potential to the mechanism revelation of SMW effect and the accurate extraction of its physical characteristics. Nevertheless, the measured vibration signals in IGBT modules by laser vibrometer typically contain a variety of other interference signals, such as thermal deformation signal, electromagnetic jamming, and background noise, in addition to the expected target SMW signals. Therefore, the aim of this work is to develop an effective signal decoupling method to realize the extraction of SMW signal from the aliasing signals obtained by laser vibration measurement.

Switching mechanical wave (SMW) occurring at switching moment in insulated gate bipolar transistor (IGBT) has attracted extensive attention in recent years. However, AE sensors widely utilized in current researches can hardly realize the SMW detection in the local area of single-tube IGBTs due to the limitations of large volume and low spatial resolution, thus hindering the further investigation of SMW effect mechanism revelation and physical properties. Therefore, this work aims to develop a high spatial resolution laser interferometric detection system to capture SMW signals at different spatial locations of single-tube IGBTs, thus enhancing the comprehension on the underlying mechanisms and physical properties of SMW effect in single-tube IGBTs.

The recently proposed induced current thermo-electrical impedance tomography (ICTEIT) is a nondestructive evaluation method for nonferromagnetic metal materials. The method reconstructs the defect profile by solving conductivity distribution from eddy currents, which has shown good performance in simple defects, but worse performance in complex defects (such as multiple adjacent defects and defects with complex contours). The main reason is that the unidirectional excitation produces low eddy current regions near the defect, which lacks reliable reconstruction information. For the problem, multidirectional excitation is able to make up for the low eddy current regions. However, previous methods simply superimpose the information of all eddy currents, and cannot integrate them for reconstruction. To solve the problem, we present a multidirectional information fusion method for defect reconstruction. The proposed method uses least squares optimization and transforms the information of multidirectional currents into a system of linear equations associated with conductivity, which constrains the solution and makes the solution satisfy each current simultaneously. Furthermore, to solve the ill-conditioning in the inverse problem, the total variation regularization method is introduced. Experiments are conducted on multiple neighboring defects and defects with complex shapes to validate the proposed method's performance.

This paper presents an investigation of dynamic thermal deformation characteristics in insulated gate bipolar transistor (IGBT) modules under bonding wire cracking condition by means of finite element simulation and experimental validation. Firstly, a realistically restored three-dimensional geometric model for IGBT modules is constructed and simulated to investigate thermal deformation field. Then the thermal deformation field characteristics under bonding wire intact and cracked conditions are compared and analyzed indepth. The result shows that the thermal deformation fluctuation amplitude of the cracked bonding wire decreases by 82%, while the thermal deformation value of other unbroken wires increases by 35% on average. Finally, the experimental verification is carried out, and the conclusion shows that it coincides well with the simulation results. This work provides confident evidence and important data to facilitate more precise life-time predictions and thermal-mechanical reliability assessment for power electronic modules.

This work emphasises the bipartite flocking of leader-follower Cucker-Smale model on cooperation-competition networks under Denial-of-Service (DoS) attacks. The DoS with limited energy is the periodic signal that consists of active periods and asleep periods. It interruptes the information interactions among agents during the activation stages, while it concentrates on storing own energy for the next attack moment during the asleep stages. Meanwhile, the control strategy to defend against DoS attacks is established. The products convergence of infinite sub-stochastic matrices method is employed to implement the bipartite flocking behavior. Based on this method, a algebraic condition which is related to initial states, the topological structure and the weight function is constructed. Moreover, the obtained theoretical results are demonstrated by numerical simulations.