Permanent magnet synchronous motor field failure diagnosis method based on residual voltage after ac dump

Abstract

The invention discloses a permanent magnet synchronous motor field failure diagnosis method based on residual voltage after ac dump and belongs to the field of electric automobile motor failure diagnosis. The method includes the steps of collecting a voltage momentary signal of any phase of a stator end at the alternating current dumping moment, capturing the waveform of the residual voltage after ac dump since the alternating current dumping moment from the voltage momentary signal, initially judging the probability of the field failure, conducting frequency spectrum conversion on the captured residual voltage after ac dump, determining a fundamental component amplitude, determining the ratio of the fundamental component amplitude to the motor speed as a failure feature, setting a failure pre-warning threshold value, determining the ratio of the failure feature to the failure pre-warning threshold value as a failure factor, and judging whether the field failure exists or not according to the failure factor. The method is not influenced by the converter supply, a permanent magnet synchronous motor is detected without being influenced by the load, the defect that the traditional diagnosis is conducted through the stator current is effectively overcome, and the field failure of the electric automobile permanent magnet synchronous motor can be quite flexibly and quite reliably diagnosed.

Description

technical field [0001] The invention relates to a method capable of diagnosing the demagnetization fault of a permanent magnet synchronous motor of an electric vehicle, and belongs to the field of fault diagnosis of a drive motor of an electric vehicle. Background technique [0002] Due to its compact structure, small size, light weight, high efficiency, high torque, high power density, reliable operation, low noise and other performance characteristics, the permanent magnet synchronous motor has the best comprehensive index for electric vehicle drive, and is very suitable for electric vehicles drive field. However, the operating environment of electric vehicle drive motors is harsh and the operating conditions are complex. The rotor permanent magnets will demagnetize under electrical, magnetic, thermal, mechanical and other stresses. Once the permanent magnets have irreversible demagnetization failures, it will lead to performance indicators of permanent magnet motors. The...

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Problems solved by technology

However, using the stator current to diagnose the motor rotor loss of excitation fault, whether it is a steady-state analysis or a transient analysis, still has certain limitations:

[0004] (1) Other types of faults of the rotor will also generate the same harmonics as above, such as dynamic eccentricity, which makes it difficult to distinguish loss of field faults from other types of faults

In addition, the output voltage of the inverter as a driving power supply is non-sinusoidal and contains a large number of time harmonics, resulting in a large number of harmonic components in the current, which brings difficulties to the use of current harmonics to diagnose demagnetization faults

[0005] (2) When the rotor has a slight demagnetization fault, the ratio of the fault frequency component to the fundamental frequency component in the stator current is very small, and the ratio is even smaller when the motor is running at light load, which brings difficulties to signal processing and makes Decreased diagnostic sensitivity

This makes it difficult to visually see whether there is a fault frequency component on the spectrogram

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