Key Takeaways & Executive Findings
- •• Comprehensive investigation of dynamic avalanche in FS-IGBT under UIS with varying circuit parameters. • Identification of gate voltage, load inductance, and temperature as key factors influencing avalanche reliability. • Proposal of a circuit parameter optimization method to enhance dynamic avalanche capability. • Practical guidelines: reduce gate voltage, increase load inductance, and lower temperature for improved reliability.
Abstract
The dynamic avalanche effect is a critical factor influencing the performance and reliability of the field-stop insulated gate bipolar transistors (FS-IGBT). Unclamped inductive switching (UIS) is the primary method for testing the dynamic avalanche capability of FS-IGBTs. Numerous studies have demonstrated that factors such as device structure, avalanche-generating current filaments, and electrical parameters influence the dynamic avalanche effect of the FS-IGBT. However, few studies have focused on enhancing the avalanche reliability of the FS-IGBT by adjusting circuit parameters during operation. In this paper, the dynamic avalanche effect of the FS-IGBT under UIS conditions is comprehensively investigated through a series of comparative experiments with varying circuit parameters, including bus voltage VDC, gate voltage VG, gate resistance Rg, load inductance L, and temperature TC. Furthermore, a method to enhance the dynamic avalanche reliability of the FS-IGBT under UIS by optimizing circuit parameters is proposed. In practical applications, reducing gate voltage, increasing load inductance, and lowering temperature can effectively improve the dynamic avalanche capability of the FS-IGBT.
1. Introduction
IGBTs are essential components in power electronic devices, frequently employed in medium to high-voltage applications, including motor drives for electric and hybrid vehicles[1−4]. A crucial aspect of their operation is the capacity to withstand high energy levels during UIS, an operating condition that can result in catastrophic device failure if not adequately managed[5−7]. The UIS test, a standard procedure for assessing the reliability of IGBTs, involves subjecting the device to an inductive load that, when interrupted, drives the device into avalanche mode, thereby stressing its capacity to manage the resulting energy surges[8−10].
The dynamic avalanche capability of an IGBT is affected by various electrical parameters, particularly current density, the rate of voltage change, and the device’s thermal management. During the UIS, the current path within the device and the resulting energy distribution can vary significantly, leading to non-uniform current conduction and the potential formation of localized hot spots that may trigger device failure through a process known as current filamentation[11−13]. Current filaments are regions of concentrated current that may migrate across the device due to the complex interplay of the electric field, impact ionization, and thermal effects, as demonstrated in experimental studies.
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Jingping Zhang, Houcai Luo, Huan Wu, Bofeng Zheng, Xianping Chen (2025). Dynamic avalanche reliability enhancement of FS-IGBT under unclamped inductive switching. SinoTechIntel Verified Research. https://doi.org/10.1088/1674-4926/25020006
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Frequently Asked Questions
What is the dynamic avalanche effect in FS-IGBTs?
The dynamic avalanche effect refers to the avalanche multiplication occurring during switching transients in field-stop insulated gate bipolar transistors (FS-IGBTs), which can lead to localized current filamentation and potential device failure if not properly managed.
How is the dynamic avalanche capability of FS-IGBTs tested?
The dynamic avalanche capability is typically tested using unclamped inductive switching (UIS), where the device is subjected to an inductive load that, when interrupted, forces the device into avalanche mode, stressing its ability to handle energy surges.
Which circuit parameters influence the dynamic avalanche reliability of FS-IGBTs?
Key circuit parameters include bus voltage (VDC), gate voltage (VG), gate resistance (Rg), load inductance (L), and temperature (TC). The study found that reducing gate voltage, increasing load inductance, and lowering temperature can improve dynamic avalanche capability.
What practical recommendations are provided for enhancing FS-IGBT avalanche reliability?
The paper recommends reducing gate voltage, increasing load inductance, and lowering operating temperature to effectively enhance the dynamic avalanche capability of FS-IGBTs in practical applications.
What is the significance of this research?
This research provides a comprehensive investigation of dynamic avalanche in FS-IGBTs under UIS and proposes a method to enhance reliability by optimizing circuit parameters, which is crucial for improving the robustness of power electronic systems.
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