CN111458666B - Permanent magnet synchronous motor winding open-circuit fault diagnosis method - Google Patents

Abstract

The invention discloses a method for diagnosing open circuit faults of a permanent magnet synchronous motor winding, which comprises the steps of collecting a plurality of bits of current data at equal time intervals to form an original sequence of a gray prediction model, substituting the original sequence into a gray prediction mathematical model to predict current data at the next moment, and then performing difference between the predicted data and the original data and comparing the difference with a set threshold value to judge whether faults exist and feed back fault signals. The method has high reliability, does not need an additional sensor, can quickly and accurately diagnose the open-circuit fault of the permanent magnet synchronous motor winding, and judges the fault position.

Description

Permanent magnet synchronous motor winding open-circuit fault diagnosis method

Technical Field

The invention relates to the field of motor fault diagnosis, in particular to a permanent magnet synchronous motor winding open-circuit fault diagnosis method.

Background

Some electrical faults often occur in the permanent magnet synchronous motor driving system, and can be generally classified into four types: power tube open circuit faults, power tube short circuit faults, winding open circuit faults and winding short circuit faults. Compared with the open-circuit fault, the short-circuit fault has a plurality of mature diagnosis schemes, and compared with the short-circuit fault, the motor can still run after the open-circuit fault occurs, so the short-circuit fault is not easy to be found, but the damage is larger, and because the rest IGBTs flow larger current under the condition, the overcurrent fault is easy to occur; and the direct current component exists in the motor current, which can cause the problems of torque reduction, heating, insulation damage and the like, and if the open-circuit fault is not processed in time, a larger accident can be caused. Therefore, it is very important to research fault diagnosis technology for normal operation of the driving system of the permanent magnet synchronous motor.

At present, there are three methods, i.e., an expert system method, a current detection method, and a voltage detection method. The expert system method is based on experience accumulation, lists possible faults one by one, generalizes rules and establishes a knowledge base, only needs to observe fault phenomena and query the knowledge base to judge fault types when faults occur, and has the difficulty that all fault phenomena are difficult to be exhausted and a complete fault knowledge base is obtained, and some fault modes are very similar to a certain state when a system normally operates, so that faults are difficult to be accurately matched. The voltage detection method has the advantages of strong robustness, high diagnosis speed and the like, but the universality is poor, and the cost and the complexity of the system are increased due to the additional arrangement of the voltage sensor. Considering the independence of system parameters and control strategies, current detection is the most common open-circuit fault diagnosis method at present, and does not need an additional sensor.

Motor winding faults are one of the most common faults, so fault diagnosis technologies for motor windings need to have higher reliability, rapidity and accuracy. In previous permanent magnet synchronous motor drive systems, the diagnosis of faults is not fast enough by relying on calculating the current in one or more cycles, which means that the motor will run in a fault state for more time, increasing system losses and risks. Meanwhile, the system has the defects of needing more electrical equipment, inevitably causing the design of the system to become more complicated, and the diagnosis is not intelligent enough.

Disclosure of Invention

The invention aims to overcome the defects in the prior art, provides the method for diagnosing the open-circuit fault of the permanent magnet synchronous motor winding, is simple and easy to implement, has high reliability and short diagnosis time, and can intelligently and effectively detect and position the open-circuit fault of the permanent magnet synchronous motor winding.

The invention adopts the following technical scheme for solving the technical problems:

a permanent magnet synchronous motor power tube open-circuit fault diagnosis method comprises the following specific steps:

step 1: collected permanent magnet motor ABC three-phase winding current i_A、i_B、i_CCarrying out abc/dq coordinate transformation to obtain dq axis actual current i_dAnd i_qThe collected actual rotation speed omega_rAnd a given rotational speed omega_rOutputting given q-axis current i after PI regulation_qWill give q-axis current i_qActual current i of x and q axes_qOutputting given q-axis voltage V after PI regulation_qWill give d-axis current i_dAnd d-axis actual current i_dOutputting given d-axis voltage V after PI regulation_dWill give q-axis and d-axis voltages V_qAnd Vd obtaining an alpha and beta axis reference voltage V through dq/alpha and beta coordinate transformation_α*、V_βReference voltage V of α β axis_α*、V_βObtaining three-phase PWM wave and inverse through voltage space vector pulse width modulationThe transformer receives the three-phase PWM wave after the voltage space vector pulse width modulation and drives the permanent magnet motor to operate;

And 2, step: several bits of current data at equal time intervals are collected and stored as the original sequence of the grey prediction model, which is recorded as:

and step 3: and substituting the original sequence into the established gray prediction model, and predicting the current value of the next step or the next steps according to the model, wherein the gray prediction model is shown as the following formula:

wherein alpha is_A、α_B、α_CA, B, C development gray scale, reaction prediction development situation, mu_A、μ_B、μ_CA, B, C three-phase control coefficients respectively reflecting the relation of data change, and alpha_A、α_B、α_CAnd mu_A、μ_B、μ_CAll can be solved according to the collected current data;

and 4, step 4: setting a fault judgment threshold r' according to the actual operation parameters of the permanent magnet synchronous motor, and predicting the current data of the next moment

With the value of the actually sampled current i_A、i_B、i_CComparing, if the absolute value of the difference between the predicted value and the actual value of one phase exceeds the threshold r', taking phase A as an example

Judging that the winding has an open-circuit fault and feeding back a fault signal; if the difference is less than or equal to the threshold, take phase A as an example

It is indicated that no failure has occurred.

The invention has the beneficial effects that: compared with the prior art, the method has the advantages of high reliability, difficulty in misjudgment, no need of an additional sensor, strong universality and capability of intelligently and effectively detecting and positioning the open-circuit fault of the permanent magnet synchronous motor winding. The diagnosis speed is high, the diagnosis variables do not need to be calculated in one period or even multiple periods, the fault can be judged only in a plurality of sampling values, and the damage to the motor caused by fault operation is greatly reduced. In addition, the fault of the one-phase or multi-phase winding can be judged, and the fault winding can be accurately positioned.

Drawings

FIG. 1 is a block diagram of an open-circuit fault diagnosis strategy for a permanent magnet synchronous motor winding according to the present invention;

FIG. 2 is a schematic diagram of a gray prediction model of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the specification, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, belong to the scope of the present invention.

As shown in fig. 1, the method for diagnosing the open-circuit fault of the power tube of the permanent magnet synchronous motor of the present invention comprises the following specific steps:

step 1: collected permanent magnet motor ABC three-phase winding current i_A、i_B、i_CCarrying out abc/dq coordinate transformation to obtain dq axis actual current i_dAnd i_qThe collected actual rotation speed omega_rAnd a given rotational speed omega_rOutputting given q-axis current i after PI regulation_qWill give q-axis current i_qActual current i of x and q axes_qOutputting given q-axis voltage V after PI regulation_qWill give d-axis current i_dAnd d-axis actual current i_dOutputting given d-axis voltage V after PI regulation _dWill give q-axis, d-axis voltage V_q*、V_dObtaining alpha beta axis reference voltage V through dq/alpha beta coordinate transformation_α*、V_βReference voltage V of α β axis_α*、V_βAnd the inverter receives the three-phase PWM waves after the voltage space vector pulse width modulation and drives the permanent magnet motor to operate.

And 2, step: several bits of current data at equal time intervals are collected and stored as the original sequence of the grey prediction model, which is recorded as:

and 3, step 3: and substituting the original sequence into the established gray prediction model, and predicting the current value of the next step or the next steps according to the model, wherein the gray prediction model is shown as the following formula:

wherein alpha is_A、α_B、α_CA, B, C development gray scale, reaction prediction development situation, mu_A、μ_B、μ_CA, B, C three phases respectively generate control coefficients reflecting the relation of data change, and alpha_A、α_B、α_CAnd mu_A、μ_B、μ_CAll can be solved according to the collected current data.

And 4, step 4: setting a fault judgment threshold r' according to the actual operation parameters of the permanent magnet synchronous motor, and predicting the current data of the next moment

With the value of the actually sampled current i_A、i_B、i_CComparing, if the absolute value of the difference between the predicted value and the actual value of one phase exceeds the threshold r', taking phase A as an example

Judging that the winding has an open-circuit fault and feeding back a fault signal; if the difference is less than or equal to the threshold, take phase A as an example

It is indicated that no failure has occurred.

Fig. 2 shows a process of building a gray prediction model, in this example, continuous 8 bits of data of equal-interval current sampling are stored, and the specific steps are as follows:

step 1: sampling a certain phase current, and recording n equal to 8 sampling data at equal time intervals as:

X⁽⁰⁾＝{x⁽⁰⁾(1),x⁽⁰⁾(2),…,x⁽⁰⁾(n)}

step 2: to X⁽⁰⁾Sequentially accumulating to generate a first-order accumulation generating sequence X⁽¹⁾：

X⁽¹⁾＝{x⁽¹⁾(1),x⁽¹⁾(2),…,x⁽¹⁾(n)}

Wherein x⁽¹⁾Is composed of

Let Z⁽¹⁾Is X⁽¹⁾Adjacent mean equal weight series of

Z⁽¹⁾＝{z⁽¹⁾(1),z⁽¹⁾(2),…,z⁽¹⁾(n)}

Wherein

z⁽¹⁾(k)＝0.5x⁽¹⁾(k)+0.5x⁽¹⁾(k-1)

Since the data in the original sequence are all the current values actually detected, the sequence X⁽⁰⁾Meets the requirement of smoothness inspection and can be used for X⁽¹⁾Establishing a GM (1,1) model;

and 3, step 3: establishing a whitening differential equation:

wherein alpha is the development gray scale, the development situation of the reaction prediction, mu is the internal generation control coefficient, the relation of the data change is reflected, and the following are set:

then order:

can be paired with

A solution is performed in which, among other things,

Y_n＝[x⁽⁰⁾(2) x⁽⁰⁾(3) ... x⁽⁰⁾(n)]^T

and 4, step 4: to be obtained

Substituting the prediction model into a whitening differential equation, solving the equation to obtain a gray GM (1,1) prediction model:

and (3) performing subtraction reduction on the formula to obtain predicted data:

although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that various changes in the embodiments and modifications of the invention can be made, and equivalents and modifications of some features of the invention can be made without departing from the spirit and scope of the invention.

Claims (1)

1. The method for diagnosing the open-circuit fault of the permanent magnet synchronous motor winding is characterized by comprising the following specific steps of:

step 1: collected permanent magnet motor ABC three-phase winding current i_A、i_B、i_CCarrying out abc/dq coordinate transformation to obtain dq axis actual current i_dAnd i_qThe collected actual rotation speed omega_rAnd a given rotational speed omega_rOutputting given q-axis current i after PI regulation_qWill give q-axis current i_qActual current i of x and q axes_qOutputting given q-axis voltage V after PI regulation_qWill give d-axis current i_dAnd d-axis actual current i_dOutputting given d-axis voltage V after PI regulation_dWill give q-axis and d-axis voltages V_q*、V_dObtaining reference voltage V of alpha-beta axis by dq/alpha-beta coordinate transformation_α*、V_βReference voltage V of α β axis_α*、V_βObtaining three-phase PWM waves after voltage space vector pulse width modulation, and receiving the three-phase PWM waves after the voltage space vector pulse width modulation by an inverter and driving a permanent magnet motor to operate;

step 2: a, B, C three-phase current is respectively collected according to equal time intervals, and a plurality of collected results are stored as an original sequence of a gray prediction model and recorded as an original sequence

Wherein:

and step 3: substituting the original sequence into the established grey prediction model, predicting the current value of the next step according to the model, and recording the predicted value as

The grey prediction model is as follows:

wherein alpha is_A、α_B、α_CA, B, C development gray scale, reaction prediction development situation, mu_A、μ_B、μ_CA, B, C three-phase control coefficients respectively reflecting the relation of data change, and alpha_A、α_B、α_CAnd mu_A、μ_B、μ_CAll can be solved according to the collected current data;

and 4, step 4: setting a fault judgment threshold r' according to the actual operation parameters of the permanent magnet synchronous motor, and predicting the current data of the next moment

With the value of the actually sampled current i_A、i_B、i_CComparing, if the absolute value of the difference between the predicted value and the actual value of one phase exceeds the threshold r', taking phase A as an example

Judging that the winding has an open-circuit fault and feeding back a fault signal; if the difference is less than or equal to the threshold, take phase A as an example

It is indicated that no failure has occurred.

Images