More Like this

1. An Adaptive Method for Mitigating Overvoltage Stress on Motor Windings Driven by SiC Inverters

   https://doi.org/10.1109/TIE.2025.3574543  

   Sadoughi, Milad; Fateh, Fariba; He, JiangBiao; Mirafzal, Behrooz (January 2025, IEEE Transactions on Industrial Electronics)

   High-performance switching devices like SiC MOSFETs introduce high-frequency ringing and overvoltage transients at motor terminals, leading to uneven voltage distribution across windings. In SiC-driven motors, the first coil and initial turns experience significant overvoltage stress, increasing the risk of insulation degradation and inter-turn faults. This study proposes an analog circuit to mitigate overvoltage stress. The circuit detects high dv/dt in the first coil and adaptively inserts a ceramic capacitor via a GaN switch, forming a low-impedance path for high-frequency currents. This diverts part of the transient energy to the second coil, reducing stress on the first coil and promoting uniform voltage distribution. The GaN switch remains closed to sustain the high-frequency current path through the capacitor, adapting to different operating conditions and cable lengths. The circuit was prototyped and experimentally validated on a 2hp induction motor driven by a SiC inverter, demonstrating its effectiveness in mitigating overvoltage stress. This compact solution enhances the reliability of SiC-driven motor systems by addressing uneven high-frequency voltage distribution. 

   more » « less
2. Smart Coils for Mitigation of Motor Reflected Overvoltage Fed by SiC Drives

   https://doi.org/10.1109/APEC43580.2023.10131221  

   Fard, Majid T.; He, JiangBiao; Sadoughi, Milad; Mirafzal, Behrooz; Fateh, Fariba (March 2023, IEEE)

   High dv/dt from the emerging SiC variable-frequency drives can easily induce overvoltage across the motor stator winding terminals, especially for long-cable-connected and high-voltage motor-drive systems. Due to the fast switching speed and surge impedance mismatch between cables and motors, this overvoltage can be two times or even higher than the DC-bus voltage of the inverter, resulting in motor insulation degradation or irreversible breakdown. The most common solution to mitigate such overvoltage is to install a dv/dt or a sinewave filter at the output of the drive, which decreases the efficiency and power density of the system. Among different stator coils, the first one (close to the drive side) is the most susceptible to insulation breakdown since it experiences higher overvoltage than the others due to the nonlinear distribution of the reflected surge voltages. In this paper, an innovative high-efficiency ultracompact mitigation solution is introduced, which is a tiny auxiliary circuit embedded inside the motor stator (or at the motor terminal box), specifically across the first few coils of each phase (i.e., smart coils). The proposed smart coil circuit effectively mitigates the surge overvoltage, which can be scalable to any type of motor-drive systems, regardless of cable length and semiconductor rise time. The proposed solution can dramatically improve the reliability, efficiency, and power density of motor-drive systems. 

   more » « less
3. A Comprehensive Review of Mitigation Strategies to Address Insulation Challenges within High Voltage, High Power Density (U)WBG Power Module Packages

   https://doi.org/10.1109/TDEI.2024.3382070  

   Adhikari, Pujan; Ghassemi, Mona (January 2024, IEEE Transactions on Dielectrics and Electrical Insulation)

   Within the expanding domain of electrical power demand, the future of power module packaging is entwined with the progress of (ultra) wide bandgap (UWBG) materials. These materials, like silicon carbide (SiC), aluminum nitride (AlN), and diamond, offer advantages with higher power density, decreased weight, and expanded operational abilities regarding temperature, voltage, and frequency. However, the pursuit of pushing these limits confronts challenges within insulation systems, which may struggle to endure the demands of these parameters, potentially resulting in unfavorable conditions like high electric field, space charge accumulation, electrical treeing, and partial discharge (PD), leading to insulation failure. The emphasis of this paper is to review the insulation challenges within (U)WBG power modules and recent research in mitigating the electric field stress at triple points (TPs) and resolving the PD issues. The manuscript first discusses the high electric field stress issue at triple points. Then, ceramic substrate materials, encapsulation materials, and the influence of harsh weather conditions on them are reviewed. The space charge, electrical treeing, and PD issues within encapsulation materials are analyzed under practical operation conditions of (U)WBG power modules like high frequency, temperature, and square wave pulses. Finally, the various strategies to alleviate the associated insulation challenges are meticulously discussed. While the identified mitigation strategies are able to strengthen insulation systems for packaging, their validation under actual operational conditions of (U)WBG power modules remains relatively unexplored, representing a potential avenue for further investigation. This review offers a valuable framework by providing the constraints of the current studies and recommendations for the future that can be utilized as a reference point for future research endeavors. 

   more » « less
4. A Review of Insulation Challenges and Mitigation Strategies in (U)WBG Power Modules Packaging

   https://doi.org/10.1109/TPEC60005.2024.10472278  

   Adhikari, Pujan; Ghassemi, Mona (February 2024, 2024 IEEE Texas Power and Energy Conference (TPEC))

   In the ever-growing landscape of electrical power demand, the future of power electronics module packaging lies in the realm of wide-bandgap (WBG) materials, including silicon carbide (SiC), gallium nitride (GaN), and cutting-edge ultra WBG (UWBG) materials like diamond, aluminum nitride (AlN), and hexagonal-boron nitride (h-BN). These materials offer superior properties to traditional silicon-based devices, promising higher power density, reduced weight, and increased operating temperature, voltage, and frequency. However, pushing the boundaries for power electronics modules presents challenges in insulation systems as the encapsulation material and the ceramic substrate may not withstand the functional parameters, potentially leading to unfavorable conditions like high field stress and partial discharge (PD), ultimately resulting in insulation failure. This paper presents a thorough analysis of the characteristics of the electrical insulation materials used in power electronics devices based on the research in WBG packaging conducted in recent years. The significance of maximum electric field stress at triple points (TPs) is examined. Furthermore, the paper reviews the strategies and techniques employed to mitigate the challenges related to maximum field stress and PDs in both encapsulation and substrate materials. It is concluded that the mitigation strategies are promising in improving insulation systems for packaging, but the studies lack their implementation under actual operating conditions of WBG power modules. 

   more » « less
5. A Review of Insulation Challenges and Mitigation Strategies in (U)WBG Power Modules Packaging

   Adhikari, Pujan; Ghassemi, Mona (March 2024, IEEE Texas Power and Energy Conference (TPEC))

   In the ever-growing landscape of electrical power demand, the future of power electronics module packaging lies in the realm of wide-bandgap (WBG) materials, including silicon carbide (SiC), gallium nitride (GaN), and cutting-edge ultra WBG (UWBG) materials like diamond, aluminum nitride (AlN), and hexagonal-boron nitride (h-BN). These materials offer superior properties to traditional silicon-based devices, promising higher power density, reduced weight, and increased operating temperature, voltage, and frequency. However, pushing the boundaries for power electronics modules presents challenges in insulation systems as the encapsulation material and the ceramic substrate may not withstand the functional parameters, potentially leading to unfavorable conditions like high field stress and partial discharge (PD), ultimately resulting in insulation failure. This paper presents a thorough analysis of the characteristics of the electrical insulation materials used in power electronics devices based on the research in WBG packaging conducted in recent years. The significance of maximum electric field stress at triple points (TPs) is examined. Furthermore, the paper reviews the strategies and techniques employed to mitigate the challenges related to maximum field stress and PDs in both encapsulation and substrate materials. It is concluded that the mitigation strategies are promising in improving insulation systems for packaging, but the studies lack their implementation under actual operating conditions of WBG power modules. 

   more » « less