A method for diagnosing open-circuit faults of neutral-point-clamped single-phase three-level inverters

Abstract

The invention discloses a method for diagnosing an open-circuit fault of a neutral-point clamped single-phase three-level inverter. The current information of the neutral-point clamped bus is obtained by changing the detection mode of the current sensor, and the two bridge arms under normal conditions are obtained through off-line calculation. The corresponding relationship between the switch state, phase current and current theoretical value detected by the current sensor is established, and the corresponding relationship between the actual value of the current detected by the current sensor and the open circuit fault of different power tubes when the phase current is different in polarity is established. According to the corresponding relationship between the detected value of the current sensor in the corresponding relationship The fault diagnosis rules are set by changing, and the single-phase three-level inverter open circuit fault diagnosis is carried out by comparing the change relationship between the current theoretical value detected by the current sensor and the actual value collected online and combined with the fault diagnosis rules. The proposed method is independent of the adopted control strategy, simple to implement, no complicated online calculation process, accurate open circuit fault diagnosis, and has good engineering application value.

Description

technical field [0001] The invention relates to an open-circuit fault diagnosis method of a power electronic converter, in particular to an open-circuit fault diagnosis method suitable for a midpoint clamp type single-phase three-level inverter. Background technique [0002] Compared with the single-phase two-level inverter, the single-phase three-level inverter has less voltage stress on each switching device and lower harmonic content of the output waveform, which is suitable for high-voltage and high-power applications. However, due to factors such as overvoltage, overcurrent, and overheating, the single-phase three-level inverter will have an open-circuit fault. If the fault is not diagnosed and located in time, it will affect the working performance of the inverter and deteriorate the output waveform. Diagnose the open circuit fault of the phase three-level inverter. The traditional methods for single-phase three-level inverter open-circuit fault diagnosis are mainly d...

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

Images