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.

With the applications of an ultra-wideband pulse signal system in many important fields such as the intelligent sensing technology for new energy automobile, the research and development of high-amplitude and fast-front pulse sources has been widely studied. To meet the demand of an ultrafast power semiconductor switch in nanosecond front pulses, the terminal failure mechanism of avalanche bipolar junction transistor in voltage ramp triggering mode is studied in this paper. The static characteristics of a simulation model are compared with those of a sample device, and the dynamic switching characteristics of the sample device were tested. On the basis of a successful device with a nanosecond switching speed, its failure phenomenon in voltage ramp triggering mode was analyzed.

Press-pack IGBT power devices are one of the core components in new power system application equipment. Due to the complex working environment and variable working conditions of power equipment, the fatigue failure of power devices will be caused over time. To ensure the safe and stable operation of key equipment in power systems, it is necessary to assess the remaining lifetime of press-pack IGBT devices, thereby timely taking appropriate actions before a device failure occurs. First, a multi-physics field model of press-pack IGBT devices is established, and the mechanical parameters affecting their aging process are analyzed. Based on the analysis results, a suitable model for press-pack IGBTs is selected from the existing lifetime prediction models, and a lifetime assessment software applicable to press-pack IGBTs is developed. Finally, a case study is conducted based on the developed lifetime assessment software, and the assessment result of devices is obtained, providing guidance for the applications of devices.

In a direct current(DC) power transmission system, the stable operation of a valve base electronics(VBE) device is crucial for its safety. However, the traditional methods for detecting the component failures in VBE device circuit boards rely on time-consuming manual inspections or rule-based automation systems, which are often inefficient and limited in the detection accuracy. To address this problem, a method for identifying the component failure areas in VBE boards is proposed in this paper, which uses an enhanced SqueezeNet deep learning model. By incorporating depth-wise separable convolutions and residual connections, the enhanced SqueezeNet model aims to improve the accuracy of component failure detection while reducing the demand for computational resources. Experiments on a VBE board component failure dataset demonstrate that the proposed method outperforms the traditional methods and the standard SqueezeNet model in terms of detection accuracy and computational efficiency, and it achieves an accuracy rate of 95.27%, which is 4.45% higher than that of the standard model. The results of this research not only enhance the efficiency and accuracy of component failure detection in VBE boards, but also provide a novel technical reference for the diagnosis of component failures in similar equipment in power systems.

The accurate and reliable switching current information is important for power electronic converters to realize closed-loop control, harmonic suppression and short-circuit protection, which is conducive to further improving the reliability of power devices. The PCB Rogowski coil current sensor has an important research value and application prospect owing to its advantages of high bandwidth, small size, low cost and low intrusion. However, its measurement accuracy is seriously limited by the drift error and droop error in the traditional integral processing circuit. A resettable integrator is used to avoid the continuous accumulation of drift error while eliminating the influence of droop error. At the same time, a digital compensation strategy for the drift error and offset error in the resettable integrator is proposed, which uses a digital signal processor to control the digital-to-analog conversion module to generate an analog compensation signal and eliminates errors by means of a high-speed subtractor. As a result, this method has advantages of a high compensation accuracy and simple adjustment, and it can greatly reduce the influence due to integral errors. Finally, double-pulse, multiple-pulse and short-circuit protection experiments were carried out based on a double-pulse test platform, and the performance of the proposed PCB Rogowski coil current sensor was verified.

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.

Compared with that in a Si device, the area of near interface oxide traps in a SiC MOSFET is wider, and the corresponding density of traps is two orders of magnitude higher. A lot of traps which are continuously capturing or releasing charges will cause the threshold voltage (Vt) to fluctuate with time, leading to the difficulty in accurately and repeatedly measuring the value of Vith. In the standard method, the value of Vith is measured using a preprocessing method to ensure the consistence in measuring the trap charge state in each time. However, the preprocessed trap state which is affected by drain-source voltages is not taken into account in the standard method, which will bring errors to the Vth test. Aimed at this problem, the transfer curves under the influences of different drain-source voltage pulses were measured at first, which show the effects of different drain-source voltages on Vth. Second, the influence of drain-source voltage on the trap charge state was analyzed based on the transient current method, thus clarifying the mechanism of the influence of drain-source voltage on traps. Finally, the influences of different drain-source voltages on Vith measurement were com-pared. Results indicate that the drain-source voltage affects the positive and negative electric field between the gate and drain, thereby affecting the trap charge state and causing the Vith drift. It is suggested that a smaller drain-source voltage should be used when measuring Vith to improve the measurement accuracy and reduce errors caused by testing factors in reliability experiments.

To study the degradation mechanism of silicon carbide metal-oxide-semiconductor field effect transistors (SiC MOSFETs) under dynamic drain-source stress, a dynamic reverse bias test platform with an adjustable dVds/dt capability up to 80 V/ns was developed. A dynamic high-temperature reverse bias test of commercial SiC MOSFET was carried out, and the effect of dynamic drain-source stress with a high voltage change rate on the electrical characteristics of SiC MOSFET was discussed. Experimental results show that the threshold voltage and forward conduction voltage of the bulk diode increased, indicating that the gate oxygen layer and the bulk diode above the JFET region of the device may be degraded. Sentaurus TCAD was used to analyze the weak position of plane-gate SiC MOSFET under high drain-source voltage and a high voltage change rate, and hole traps were set at the gate oxygen layer junction and the body diode region to simulate the effect of dynamic high-temperature reverse bias on the dynamic and static parameters of SiC MOSFET.