Asymmetric fault diagnosis method and system for stator of permanent magnet synchronous motor

Abstract

The invention discloses an asymmetric fault diagnosis method and system for a stator of a permanent magnet synchronous motor. The method includes the steps: performing FFT (fast Fourier transformation) on three-phase current and voltage signals of the stator to obtain fundamental waves of each phase of current and voltage; applying a symmetrical component analysis method for computation to obtain fundamental wave negative sequence current and voltage; then computing to obtain fundamental wave negative sequence impedance and fundamental wave negative sequence current phase angle difference, and acquiring maximum phase angle deviation of the fundamental wave negative sequence current; taking the maximum phase angle deviation of the fundamental wave negative sequence current, magnitude of the fundamental wave negative sequence current and the fundamental wave negative sequence impedance as three input variables of fuzzy logic, and utilizing a weighted fuzzy logic algorithm to judge whether an asymmetric fault exists or not and fault degree. The system comprises the permanent magnet synchronous motor, a Hall current and voltage sensor, a signal conditioning circuit, a data acquisition instrument, a fault diagnosis center and a vehicle-mounted display circuit. The method and system is high in reliability, wide in application range and capable of being used for asymmetric fault diagnosis of the stator for different reasons.

Description

technical field [0001] The invention relates to a fault diagnosis method and system for stator asymmetry of a permanent magnet synchronous motor, belonging to the field of state detection and fault diagnosis of a driving motor. Background technique [0002] The driving motor is the core equipment of electric vehicles and the source of power for vehicles. Its reliability directly affects the driving safety of electric vehicles. The high power density, high efficiency, wide speed range and high overload capacity of permanent magnet synchronous motors make them an ideal choice for electric vehicle drive motors, and my country has rich rare earth resources, so the permanent magnetization of electric vehicle drive bodies is very important. Important trends in its drive system development. However, permanent magnet synchronous motors, like other rotating motors, may have various faults during long-term continuous operation, which seriously affects the reliability and safety of mot...

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Problems solved by technology

[0004] (1) Some scholars have studied the operating characteristics of self-starting permanent magnet synchronous motors under three-phase asymmetrical voltage, but their focus is on analyzing the external performance of permanent magnet synchronous motors, such as torque, speed and rotor copper loss etc., did not study the negative sequence component, and the starting point is not the diagnosis of asymmetrical faults;

[0005] (2) In the relevant literatures that use the negative sequence component to analyze the short-circuit fault between the stator turns of the traditional asynchronous motor and the synchronous motor, the focus is only on one of the two parameters of the negative sequence current or the phase angle difference of the negative sequence current. Analysis, because the negative sequence current is easily affected by the load size and speed, the stability is limited to a certain extent, which reduces the accuracy of fault judgment. Therefore, how to integrate other methods to improve the accuracy and stability of fault diagnosis is an urgent task. One of the problems to be solved;

[0006] (3) The literature is more focused on the fault diagnosis method caused by a specific cause based on the specific harmonic analysis of the stator current. The early fault harmonic signal is relatively weak, the motor operating environment is different, and the external signal interference is also different. How to effectively Extracting the real signal is a problem worthy of in-depth study; different signal processing methods have their own advantages and scope of application, what kind of signal processing method to use after extraction to obtain the real harmonic components, research in this area is controversial, there is no one yet Consensus approach to analysis and therefore flawed

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