Wuhan University

Weiwei Zhang

Yigang He

Liulu He

Lie Li

Mingyun Chen

Xiaoyu Liu

Chuankun Wang

Xiao Wang

A method and a system for diagnosing an open circuit (OC) fault of an insulated gate bipolar transistor (IGBT) of a T-type three-level (T3L) inverter under multiple power factors based on instantaneous current distortion are provided. Similar characteristics of current distortion may be caused by an OC fault of a T3L inverter, making it is difficult to locate the fault. The method for diagnosing an OC fault of a grid-connected T3L inverter, can diagnose the OC fault hierarchically; four switch transistors in a phase can be divided into two groups according to the similarity analysis of current distortion under different power factors; group-based fault diagnosis is realized by half cycles in which a zero domain occurs; and then, a specific switching signal is injected to realize equipment-based OC fault diagnosis. The OC fault diagnosis of a T3L inverter is realized without additional hardware circuits.

Method and system for diagnosing open circuit (OC) fault of T-type three-level (T3L) inverter under multiple power factors

The invention discloses a method and a system for correction of the junction temperatures of an IGBT module in a photovoltaic inverter. The method includes: constructing an electrothermal coupling model of an IGBT model based on a photovoltaic inverter topology, a light radiation intensity, and an ambient temperature; selecting an IGBT collector-emitter on-state voltage drop as an aging parameter and designing an on-state voltage drop sampling circuit to ensure measurement accuracy; constructing an aging database for IGBT modules in different aging stages based on large current and small current injection methods; comparing a junction temperature value output by the electrothermal coupling model with the calibrated junction temperature value and calibrating an aging process coefficient of an electrothermal coupling model correction formula; comparing an IGBT aging monitoring value with the aging threshold to determine the aging process and selecting a corresponding aging process coefficient to ensure accuracy of junction temperature data.

Method and system for online correction of junction temperatures of IGBT in photovoltaic inverter considering aging process

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Hubei, China

Weiwei Zhang