Shumei Cui’s research while affiliated with Harbin Institute of Technology and other places

With the development of high-frequency and high-voltage traction machines (TM) incorporating hairpin windings (HW) and SiC inverters for electric vehicles (EV), both the interturn voltage stress and temperature within HW are rising, increasing the risk of partial discharge (PD), and presenting significant challenges to insulation safety. Therefore, this paper addresses this issue and proposes potential solutions. Firstly, the paper examines an 8-pole, 48-slot, 6-layer HW TM to highlight the unique characteristics of this winding structure, and explains the uneven distribution of interturn voltage stress and temperature. Subsequently, a high-frequency equivalent circuit model of the HW TM prototype is developed. The error of simulation and experiment is only 5.7%, which proves the accuracy of the model. Then, an improved HW scheme is proposed to lower the maximum voltage stress by 29.3 %. Furthermore, the temperature distribution of HW TM is analyzed to facilitate a detailed examination of the impact of temperature on insulation PD. Finally, the partial discharge inception voltage (PDIV) of interturn insulation, considering temperature effects, is calculated and verified through experiment. The paper proposes a reliability-oriented design method and process for HW TM. It demonstrates that the reliability-oriented design can achieve PD-free performance in the design stage of HW.

A proper lifetime model is beneficial to the reliability evaluation of power converters. In this paper, a lifetime model for solder layer aging of power module is proposed, with thermal resistance growth rate as the characteristic quantity. The focus is on the effect of pulse duration on module lifetime in power cycling test. The increase in thermal resistance of the solder layer is extracted by transforming the transient thermal impedance curve. A double linear damage accumulation model is proposed to describe the initiation and propagation of cracks in the solder layer during the aging process of the module. The effect of different pulse durations on the aging of solder layers is analyzed through finite element simulation and power cycling test results. By comparing with conventional models, the accuracy of the proposed model for lifetime prediction under variable load conditions is demonstrated.

The acoustic signal contains a wealth of features and information, which can be used as a promising substitute for vibration signals in some cost-limited applications for motor fault diagnosis. This work presented a method involving the detection of motor rotor faults using acoustic signals, to diagnose the demagnetization faults and the eccentricity faults. The acoustic signals in different motor conditions are first de-noised by wavelet packet transform to remove the irrelevant components, then the MFCCs are extracted as the features by the reason of satisfactory performance in sound recognition. Next, the features are converted into 2D images, and the fault diagnosis and classification are realized by the DeiT classifier. Experiments show that compared with other time-frequency domain analysis, e.g. HHT, or the processing method that does not convert to 2D feature images, the accuracy of the proposed method is the highest, reaching 99.26%, proving that the method is reliable and effective for accurate fault diagnosis in a non-invasive manner.

Thermal network models provide an indirect and noninvasive method for on-line junction temperature estimation of power semiconductor devices. Currently, thermal network model parameters are mainly extracted from finite element models (FEM) or calculated from material property parameters and geometries. However, as the power module ages, the parameters of the thermal network model change, resulting in inaccurate junction temperatures estimated by the preset thermal network model. This paper proposes a thermal network model for long-term junction temperature monitoring of power modules, taking into account cooling conditions and thermal coupling between chips. By measuring the junction temperature cooling curves in the standby state existing in the operating conditions and updating the parameters of the thermal network model using the identification results of the artificial intelligence algorithm, the synchronisation between the thermal network model and the health state of the power module is achieved, and the aging degree and aging location of the power module are monitored. The algorithm, implementation and result analysis of the proposed method are presented in this article. Experimental verification is given to prove the effectiveness, accuracy and convenience of the proposed method.

Wireless power transfer (WPT) technology applied to underwater environments has the advantages of no electrical contact, high safety, and high applicability. Underwater capacitive power transfer (UCPT) technology shows great potential in the field of underwater wireless power transfer as it has more advantages compared to underwater inductive power transfer (UIPT) technology. This paper begins with the system principles of UCPT and explains the advantages of UCPT technology for underwater applications. It then reviews the coupler and equivalent circuit models currently used for UCPT in various underwater environments, which indicates the direction for the design of underwater couplers in the future. In addition, compensation networks currently applied in UCPT systems are summarized and compared. Furthermore, different application examples of UCPT are introduced, and the key factors constraining UCPT development are pointed out. Research directions for future development of UCPT technology are also investigated.