A method for diagnosing open-circuit faults of switching tubes in three-phase bridge pwm rectifiers based on current phase angle

Abstract

The invention discloses a three-phase bridge PWM rectifier switching tube open-circuit fault diagnosis method, and belongs to the field of a three-phase AC / DC converter. The invention aims to solve the problems of inaccurate, poor robustness and the like in multi-tube fault diagnosis in an existing diagnostic scheme. The method uses the characteristic that a fault phase grid-side current occurs to be a zero region when an open-circuit fault happens to any one of switching tubes in a three-phase bridge PWM rectifier, a current phase angle is extracted from a three-phase grid-side current, and fault detection and positioning are achieved according to the variation amount of the current phase angle and a power grid phase angle. The method disclosed by the invention can achieve effective diagnosis of open-circuit faults of both a single switching tube and a plurality of switching tubes in the three-phase bridge PWM rectifier, the software algorithm is simple, no additional hardware circuit is required, and the transient state of a system is highly robust.

Description

technical field [0001] The invention discloses a switch tube open-circuit fault diagnosis method for a three-phase bridge PWM rectifier, which belongs to the field of three-phase AC-DC conversion. Background technique [0002] Compared with the traditional uncontrolled rectification or phase-controlled rectification scheme, the three-phase bridge PWM rectifier has the advantages of controllable DC voltage, unit power factor, small grid-side current harmonics, and bidirectional flow of energy. Power occasions have been widely used. With the large-scale use of power converters, real-time and efficient diagnosis of their faults has gradually become a research hotspot. The survey shows that about 38% of the power conversion system failures are caused by the failure of power switching devices, mainly including short-circuit faults and open-circuit faults. For short-circuit faults, because it will instantly cause damage to other normal components in the system due to overvoltage...

AI Technical Summary

Problems solved by technology

The "per unit mean value method" uses the current PARK vector modulus length to normalize the three-phase current, simplifying the algorithm; by detecting the voltage diagnosis between the midpoint of the DC side and the midpoint of the AC side to eliminate the impact of the load mutation on the diagnosis, but it needs Add a voltage sensor

In addition, the above methods only consider the open-circuit failure mode of a single switch tube. When multiple tube failures occur, faulty tube positioning errors may occur or failures cannot be detected.

From the perspective of reliability, it is not comprehensive enough to study only single-tube open-circuit faults, and it is necessary to study the failure mode of multiple-tube open-circuit at the same time

Some schemes propose to use current phase angle derivatives for fault detection, which achieves good anti-false alarm ability for load mutations, and use normalized phase current average absolute value error for fault location, which can realize multi-tube fault detection, but the detection and Positioning is implemented in two steps, and the algorithm is complex

[0005] To sum up, the open-circuit fault diagnosis method of switching tubes of three-phase bridge PWM rectifiers given by the existing literature and patents can realize multi-tube open-circuit fault diagnosis, reduce There are still many shortcomings in the evaluation of small hardware costs, simple implementation algorithms, and high robustness to system transients.

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