A high-power npc three-level inverter power module current online detection method

Abstract

The present invention provides a method for online detection of power module current of a high-power NPC three-level inverter, comprising the following steps: step 1, detecting the positive and negative busbars and load currents of each phase, and the rate of change of positive and negative busbar currents; step 2 , to count the current paths of the single-phase circuit; Step 3, according to the direction of the single-phase load current, establish the relationship model between the positive and negative busbars and load current in the single-phase topology and the current of the 4 IGBT modules and 2 clamping diode modules; Step 4 , classify short-circuit faults and count the possible short-circuit current paths of single-phase circuits; step five, detect short-circuit currents, and establish short-circuit current path identification rules according to the mutation characteristics of the detected currents; this detection method is simple and can accurately obtain each The switching transient current of the module, and when a short-circuit fault occurs in the inverter, the detection system can quickly identify the fault line and improve the efficiency of short-circuit fault diagnosis.

Description

technical field [0001] The invention relates to the field of detection of power electronic devices, in particular to an online detection method for a power module current of a high-power NPC three-level inverter. Background technique [0002] NPC three-level topology is a very widely used topology in high-power inverter systems at present. Its relatively complicated control algorithm and topology increase the difficulty of reliable operation of power modules. During system debugging, usually only the output voltage and current of the load are detected to observe the operating status of the system, but the detection of the internal power module of the system is ignored, which is not conducive to accurately evaluating the reliability of the system operation. The current of the power module provides switching transient overshoot and oscillation characteristics, which can be used to evaluate the working condition of the power module. It is an important parameter of the power mod...

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Problems solved by technology

The traditional current detection method is to detect the power module separately. However, the NPC type three-level single-phase topology has 4 IGBT modules and 2 clamping diode modules, a total of 6 power modules. If each power module of the three-phase topology is If the module performs independent detection, a total of 18 current detection units are required, which undoubtedly increases the cost of system detection

[0003] In addition, the short-circuit fault of the system is an important factor affecting the reliability of the system. When a short-circuit fault occurs in the system, the secondary fault caused by the short-circuit fault often increases the difficulty of system fault diagnosis. The traditional short-circuit detection method only quickly protects the short-circuit, and The short-circuit state cannot be detected, so when there is a problem with the short-circuit protection circuit and a serious destructive fault occurs, it is difficult to quickly find out the cause of the short-circuit fault

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