An In-Situ On-Board Offline Diagnostic Method of IGBT Modules for Bond Wire Degradation Within High-Power 3L-NPC Converters

An In-Situ On-Board Offline Diagnostic Method of IGBT Modules for Bond Wire Degradation Within High-Power 3L-NPC Converters

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Performing in-situ diagnosis is a crucial task during routine inspections of high-power converter systems, such as mine hoist.This paper presents an on-board precis vodka offline condition assessment method for bond wire degradation of high-power IGBT modules within three-level neutral-point clamped (3L-NPC) converter.This method is based on the increment of the on-state voltage $V_{mathrm {on}}$ during series short-circuit (SSC).The SSC is formed by the conduction of the IGBT modules to be tested and the external constant current switch (CCS).In CCS circuits, a PI-controlled gate drive circuit is employed to achieve high constant short-circuit current and maintain the stability of the $V_{mathrm {on}}$.

The improved $V_{mathrm {on}}$ detection circuit takes the decrement of charging time $t_{mathrm {cp}}$ of the capacitor as the parameter for aging assessment.It simplifies the data processing of $V_{mathrm {on}}$ , while increasing the aging sensitivity.To validate the effectiveness of this method in practical applications, a single-phase 3L-NPC experimental platform was built to simulate the aging state of IGBTs by cutting off the bonding wires.The feasibility of the detection circuit, the influence of short-circuit current and rico reserve clarinet mouthpiece ambient temperature on $t_{mathrm {cp}}$ , and the reliability of the CCS circuit are analyzed in detail.