Open-circuit fault diagnosis method for neutral-point clamped single-phase three-level inverter

Abstract

The invention discloses an open-circuit fault diagnosis method for a neutral-point clamped single-phase three-level inverter. The method comprises the following steps of: obtaining neutral-point clamping bus current information by changing a detection mode of a current sensor, and obtaining a corresponding relationship among a switching state of two bridge arms under a normal condition, a phase current and a theoretical current value detected by the current sensor through off-line calculation; establishing a corresponding relation between a current sensor detection current actual value and different power tube open-circuit fault conditions when the phase current has different polarities, and setting a fault diagnosis rule according to the change of the current sensor detection value in thecorresponding relation; and carrying out the open-circuit fault diagnosis of the single-phase three-level inverter by comparing the change relationship between the theoretical current value detectedby the current sensor and the actual value acquired on line and combining a fault diagnosis rule. The method provided by the invention is independent of an adopted control strategy, is simple to implement, does not need a complex online calculation process, is accurate in open-circuit fault diagnosis, and has a good engineering application value.

Description

technical field [0001] The invention relates to an open-circuit fault diagnosis method for a power electronic converter, in particular to an open-circuit fault diagnosis method suitable for a neutral point clamp type single-phase three-level inverter. Background technique [0002] Compared with single-phase two-level inverters, single-phase three-level inverters have smaller voltage stress on each switching device and lower harmonic content in output waveforms, making them suitable for high-voltage and high-power applications. However, due to factors such as overvoltage, overcurrent, and overheating, single-phase three-level inverters will have open-circuit faults. If the fault is not diagnosed and located in time, the working performance of the inverter will be affected and the output waveform will be deteriorated. Diagnose open-circuit faults of three-phase three-level inverters. The traditional open-circuit fault diagnosis methods for single-phase three-level inverters a...

AI Technical Summary

Problems solved by technology

The hardware-based fault diagnosis method needs to add additional hardware circuits, which increases the system cost. At the same time, the introduction of hardware circuits will affect the reliability of the system; the software-based fault diagnosis method is usually realized by collecting voltage or current information and using data processing algorithms. The data processing algorithms used mainly include coordinate transformation and Fourier analysis, etc., but this type of data processing algorithm has the disadvantages of large data processing volume and difficulty in online implementation, and the data processing results are usually affected by the working conditions of the inverter, so it is not applicable in a dynamic work environment

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