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...

Examples

Embodiment Construction

[0041] An embodiment of the present invention will be further described below in conjunction with accompanying drawing:

[0042] The topology of the neutral-point clamped single-phase three-level inverter is as follows: figure 1 As shown, among them, i ph is the phase current value, i o1 is the clamp current at the midpoint of the left bridge arm, i o2 is the midpoint clamping current of the right bridge arm, S 1 ~S 8 is the power triode, D 1 ~D 4 is the freewheeling diode, U d is the DC side voltage, C 1 and C 2 is the capacitor, o is the midpoint of the capacitor, and each phase bridge arm of the inverter is composed of four power transistors. The relationship between the midpoint clamp current of the two bridge arms and the current sensor current is as follows: figure 2 As shown, it is agreed that the positive direction of the reference current of the current sensor is from the inside to the outside, i o1 Penetrate the current sensor with one pass in the positiv...

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...

Examples

Embodiment Construction

[0041] An embodiment of the present invention will be further described below in conjunction with accompanying drawing:

[0042] The topology of the neutral-point clamped single-phase three-level inverter is as follows: figure 1 As shown, among them, i ph is the phase current value, i o1 is the clamp current at the midpoint of the left bridge arm, i o2 is the midpoint clamping current of the right bridge arm, S 1 ~S 8 is the power triode, D 1 ~D 4 is the freewheeling diode, U d is the DC side voltage, C 1 and C 2 is the capacitor, o is the midpoint of the capacitor, and each phase bridge arm of the inverter is composed of four power transistors. The relationship between the midpoint clamp current of the two bridge arms and the current sensor current is as follows: figure 2 As shown, it is agreed that the positive direction of the reference current of the current sensor is from the inside to the outside, i o1 Penetrate the current sensor with one pass in the positiv...

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