Power semiconductor devices are the core of electric energy conversion and electric drive based on the power electronics technology, which have broad application prospects in new energy generation, transportation, aerospace and other fields. However, the problems such as degradation, failure and reliability caused by heat generation have become bottlenecks that limit their further development, and it is urgent to explore effective thermal management methods to improve their reliability and service life. In this paper, based on the introduction of thermal management methods for power modules, the research progress in active thermal management methods is reviewed in detail, and these methods are divided into device-level, system-level and multi-parameter comprehensive methods according to the difference in control parameters. In addition, various methods are analyzed and compared. Finally, the development trend and prospect of technologies for power devices which are related to junction temperature are put forward, providing a reference for the subsequent research and applications.

Press-pack insulated gate bipolar transistor (PP-IGBT) modules are widely used in high-power applications such as flexible DC converter valves owing to their superior electrical performance and reliability. Therefore, an accurate observation of the junction temperature of a IGBT chip is important for monitoring its operating status and evaluating its remaining lifetime. The existing junction temperature observation methods are mostly designed for bonded-lead IGBTs, which cannot be applied directly because the characteristics of PP modules are not taken into account. Aimed at the PP IGBTs in large-capacity converter valves, a practical method for calibrating the on-state voltage drop and junction temperature of modules is proposed, and the online estimation error of junction temperature is comprehensively analyzed. Then, a junction temperature calibration scheme is designed based on a 5SNA 3000K452300 PP IGBT module(4 500 V, 3 000 A) produced by ABB, including experimental circuits, temperature calibration range selection, junction temperature control method, measurement circuits and calibration experimental procedure. Finally, based on a pulse test platform, the proposed method was verified. Experimental results show that the junction temperature calibration and observation scheme proposed was effective, the junction temperature observation error was within ±5 °C, and it can be applied to the case of differences in PP IGBT modules.

As a novel and extensively applied switching device, silicon carbide metal-oxide-semiconductor field-ef fect transistor(SiC MOSFET) offers a faster switching speed and lower device loss in practical applications, thereby en-hancing the converter efficiency and delivering a superior performance. Aimed at the driving characteristics of SiC MOS-FET, the influence of parasitic parameters on its performance was analyzed. To investigate the relationship between the gate-source voltage and turn-on time of SiC MOSFET, a two-pulse experimental platform was also established. However, there are certain drawbacks with the existing domestic SiC MOSFET. Based on the experimental platform and other power products, the changes in conduction time, driving loss and negative voltage amplitude after replacing the imported SiC MOSFET with domestic devices were analyzed.

Owing to its advantages including lower switching stress, harmonic components and a better anti-interference capability, the diode neutral point clamped (NPC) three-level inverter has become a prominent topology for DC-AC converters used in new energy fields such as photovoltaic and energy storage. The NPC three-level insulated gate bipolar transistor(IGBT) power semiconductor module which is widely used in high-power applications is studied. The commutation circuit in the NPC three-level power module is analyzed, and a precise simulation and evaluation method for the corresponding parasitic parameters is given. According to the principle of minimizing the parasitic parameters of the commutation circuit, a dynamic characteristic test circuit suitable for the NPC three-level power semiconductor module is designed. Based on the commutation circuit and the operating principle of circuit, a drive circuit for the NPC three-level power module is designed, and a driving scheme that enhances drive current, prevents shoot-through and allows for adjustable dead time is formulated. Finally, through dynamic testing of the NPC three-level IGBT module, a comprehensive assessment of the dynamic loss in power devices under various operating conditions is conducted.

AC-DC Buck-type power factor correction (PFC) converters are widely applied in low-voltage scenarios. However, they typically suffer from low power factor(PF) and high total harmonic distortions of input current(THDi) caused by the input current dead zones. To solve this problem, firstly, a high PF Buck-type bridgeless PFC converter with hybrid operation modes is proposed by introducing a Buck-Boost converter cell, which operates in the Buck and Buck-Boost modes in the positive and negative half-line cycles, respectively. Although the Buck-Boost cell's efficiency is inferior to that of the Buck cell, the proposed converter can operate in the Buck-Boost mode in the negative half-line cycle, thereby minimizing the dead zones to improve PF and reduce THDi. The proposed converter operates in the Buck mode in the positive half-line cycle, inheriting the high efficiency of the Buck cell. Secondly, the operation modes and PF of the proposed bridgeless converter are analyzed to show its high PF feature. Finally, simulations and experimental tests were conducted to verify the feasibility and theoretical analysis of the proposed converter, and a comparison of performance between the proposed and conventional Buck-type PFC converters was also performed.

LLC resonant converters are widely applied in on-board power supplies owing to their high power density, high efficiency and small size, and their reliability is critical to the driving safety and passenger experiences. However, the complicated working conditions and harsh environment under which vehicles operate have become a huge challenge to power devices. When a switch failure occurs, the resonant converter cannot maintain a stable output voltage while operating at a resonant point, and both efficiency and output capability of the system will decrease substantially. To make the converter more compatible with fault occasions, an improved LLC topology and its control strategy are proposed in this paper, which can ensure that the output voltage remains unaffected when a switch failure occurs and the converter operates near the resonant frequency. Additionally, an optimized Burst control strategy is designed to suppress the overvoltage of the resonant capacitor during the fault tolerance transition and guarantee a smooth fault tolerance process. Finally, simulation and experimental results verified the effectiveness of the proposed method.

In the burgeoning field of new energy vehicles, silicon carbide representing a new generation of semi-conductor power devices is progressively replacing silicon-based IGBTs, which also sets higher standards for the motor control performance within the corresponding innovative technological ecosystem. The precision of motor parameters is becoming increasingly critical for enhancing the performance of electric control systems as they evolve from the tradi-tional PI control and direct torque control to advanced algorithms such as model predictive control and neural network control. Aimed at the problem that the classic linear model for permanent magnet synchronous motors cannot adapt to complex and variable conditions due to nonlinear factors such as cross-saturation, a nonlinear magnetic flux identifica-tion method based on Gaussian process regression is proposed. By employing a second-order generalized integrator to acquire the magnetic flux data under dynamic conditions, the system identification is completed. Finally, the effective-ness of the proposed approach and the accuracy of parameter identification were verified through simulation and experi-mental results.

The application of wide bandgap semiconductor devices makes the motor drive system of electric vehicles (EVs) more compact and lightweight, but it also causes more serious electromagnetic interference (EMI), which makes the reliability of the drive system face severe challenges. To solve this problem, a 24 V/2 A EMI DC filter is taken as an example, and through the analysis of noise source, filter principle and impedance influence, the filter parameters are designed according to the index of insertion loss. At the same time, considering the starting impact at the starting time of the whole vehicle, a soft starting circuit is added to further improve the reliability of the EV drive system. Experimental results verified the EMI suppression effect and the soft starting function of the filter, proving the feasibility and effectiveness of the filter design.

In the development of technologies for power electronic devices used in automobiles, the power modules are developing towards the direction of miniaturization and high power density. As a result, the high-frequency switching of power devices used in automobiles will increase the fatigue failure risk of bonding wires. To improve the strength and reliability of bonding, the action mechanism of bonding parameters at different stages was revealed from the perspective of the bonding principle at first, and the optimization intervals for different parameters were obtained using single-factor experiments. Subsequently, a systematic investigation of the influence of wire bonding materials on bonding reliability was conducted through numerical simulations and aging tests. Results indicate that compared with Al bonding wires, Cu bonding wires exhibited higher maximum temperatures and higher maximum equivalent stress. However, due to material properties, Cu bonding wires only achieved half the maximum plastic strain of Al bonding wires. Based on power cycling tests, the lifetime of Cu bonding wires was approximately four times that of Al bonding wires. Moreover, Cu bonding wires exhibited a higher degree of variability in bonding quality, with the phenomenon of stepwise signal escalation due to the detachment of a single wire serving as an early warning signal for potential failures in daily operations.

Press-pack IGBT power devices are the core component in the new power system application equipment, and health management can improve their service lifetime and operational reliability, thus guaranteeing the safety and stability of new power systems. First, the package structure and main failure modes of press-pack IGBT devices are introduced. Second, the existing health condition monitoring methods are classified and analyzed according to different types of characteristic parameters. Third, the principles and characteristics of the existing lifetime prediction methods for press-pack IGBTs are summarized. Finally, a comprehensive comparative analysis of the existing health management technologies is performed, and the problems in the health management methods for press-pack IGBTs which need to be further studied and the development trends in the future are pointed out.