CN110309535B - Permanent magnet local loss-of-field fault simulation method and fault injector - Google Patents
Permanent magnet local loss-of-field fault simulation method and fault injector Download PDFInfo
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Abstract
The invention relates to the technical field of motor faults and discloses a method for simulating a local demagnetization fault of a permanent magnet and a fault injector, which aim to realize the simulation of the local demagnetization fault of the permanent magnet by simultaneously considering the factors of aging demagnetization and temperature demagnetization; the method comprises the steps of establishing a first relation model of magnetic induction intensity and time under aging demagnetization of the permanent magnet; establishing a second relation model of the magnetic induction intensity and the time of the permanent magnet under temperature demagnetization in more than one temperature change period; establishing a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period; establishing a motor stator current signal model; and establishing a motor stator harmonic current amplitude evolution law under the respective action of aging demagnetization and temperature demagnetization and the combined action of the aging demagnetization and the temperature demagnetization in more than one temperature change period to obtain stator harmonic current signal models in the three modes, and carrying out local demagnetization fault simulation on the permanent magnet.
Description
Technical Field
The invention relates to the technical field of motor faults, in particular to a method for simulating local magnetic loss faults of a permanent magnet and a fault injector.
Background
The permanent magnet motor has high efficiency, high torque-mass ratio, high power density and good control performance, and is more and more widely applied to the fields of high-speed trains, wind power generation, electric automobiles, aviation, national defense and the like. Although permanent magnet synchronous motors have received attention for their many advantages. But also has the defects of high cost, difficult starting, loss of magnetism of the permanent magnet and the like, and simultaneously, people also put higher and higher requirements on the running safety and reliability of the permanent magnet motor. Compared with an electric excitation motor such as an asynchronous motor, the permanent magnet motor has the biggest problem that permanent magnet materials have the risk of loss of excitation. When the permanent magnet is demagnetized, the no-load potential of the motor is reduced, the motor is abnormally heated, various performances such as torque and the like are degraded, and even the motor is damaged in serious conditions. Therefore, the method has very important significance for the research of the loss of field fault of the permanent magnet motor. In practical situations, the factors causing the loss of magnetism of the permanent magnet are many, and mainly focus on aging, temperature, external magnetic field, vibration, chemistry and the like. Different use conditions and different effects caused by various demagnetization factors are different. However, aging demagnetization and temperature demagnetization exist no matter under the use condition, and particularly, the temperature demagnetization is a main factor of the permanent magnet motor for generating irreversible demagnetization.
The flux loss of the permanent magnet over time is approximately linear with the elapsed time; the change of temperature can cause the magnetic property of the permanent magnet to change, and the magnetic property of the permanent magnet material can be lost at high temperature. When the permanent magnet rises to a certain temperature, the magnetic performance of the material is gradually reduced along a demagnetization curve, and after the temperature returns to an initial value, the magnetic induction intensity of the permanent magnet is gradually recovered, but the magnetic induction intensity cannot return to the original value, but a part of loss occurs, and the irreversible loss can cause irreversible demagnetization of the permanent magnet. The permanent magnet motor field loss fault research is destructive test research, a plurality of uncontrollable factors exist, in addition, the field loss is an irreversible process, and the faults are difficult to simulate in actual operation environments such as high-speed trains, electric automobiles, wind power systems and the like. The existing permanent magnet motor software simulation mostly takes simulation, simulation and verification of normal operation behaviors of a permanent magnet motor as main targets, and few abnormal working conditions for simulating faults of the permanent magnet motor exist, particularly simulation of a permanent magnet demagnetization evolution rule considering aging demagnetization and temperature demagnetization at the same time.
Therefore, a fault simulation method for the local demagnetization evolution law of the permanent magnet considering both aging demagnetization and temperature demagnetization is needed to be designed.
Disclosure of Invention
The invention aims to provide a method for simulating a local demagnetization fault of a permanent magnet and a fault injector, which are used for realizing the simulation of the local demagnetization fault of the permanent magnet by simultaneously considering the factors of aging demagnetization and temperature demagnetization.
In order to achieve the aim, the invention provides a local field loss fault simulation method for a permanent magnet, which comprises the following steps of:
s1: establishing a first relation model of the magnetic induction intensity and the time under the aging demagnetization of the permanent magnet according to the timeliness of the permanent magnet; establishing a second relation model of the magnetic induction intensity and the time of the permanent magnet under temperature demagnetization in more than one temperature change period according to the temperature loss characteristic of the permanent magnet;
s2: establishing a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period according to the first relation model and the second relation model;
s3: collecting stator current fault characteristic frequency when a permanent magnet local loss of excitation fault occurs in the permanent magnet motor, and establishing a motor stator current signal model under the condition of the permanent magnet local loss of excitation fault according to the stator current fault characteristic frequency and the permanent magnet local loss of excitation evolution model;
s4: and establishing a relationship between the magnetic induction intensity variation and the stator harmonic current under the loss of the permanent magnet according to the motor stator current signal model, establishing a motor stator harmonic current amplitude evolution rule under the respective action of aging demagnetization and temperature demagnetization and the combined action of the aging demagnetization and the temperature demagnetization in more than one temperature variation period to obtain stator harmonic current signal models under the three modes, and carrying out local loss of the permanent magnet fault simulation according to the stator harmonic current signal models under the three modes.
Preferably, the S1 specifically includes the following steps:
s11: the magnetic flux loss of the permanent magnet along with time is approximately in a linear relation with the elapsed time, a first relation model of the magnetic induction intensity and the time under the aging demagnetization of the permanent magnet is established, and the calculation formula is as follows:
Bs＝B0-k1t；(1)
in the formula, BsFor the magnetic induction of permanent magnets under aging demagnetization, B0Is the initial magnetic induction of the permanent magnet, k1Is an aging demagnetization factor, and t is time;
s12: establishing the relationship between the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet, wherein the calculation formula is as follows:
in the formula, BwIs the magnetic induction of the permanent magnet under temperature demagnetization, k2Is a temperature demagnetization factor;
establishing a second relation model of the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet in more than one temperature change period, wherein the calculation formula is as follows:
in the formula (I), the compound is shown in the specification,
the magnetic induction intensity of the permanent magnet under temperature demagnetization in n temperature change periods,
the initial working temperature T is the jth repeated work0The corresponding initial magnetic induction intensity is obtained,
for the jth repeated working temperature T1The corresponding magnetic induction, j is 1,2, …, n, n is the total number of repeated work; t is tj-1，jFor the jth repeated working temperature T1Corresponding time, and tj-1＜tj-1，j＜tj，k3Is the magnetization factor in a single cycle.
Preferably, before the second relation model of the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet in more than one temperature change period is established, the method further comprises the following steps: establishing a relation curve of the permanent magnet magnetic induction intensity and time under temperature demagnetization in more than one temperature change period
Said relation curve
And calculating according to the irreversible demagnetization quantity in each temperature change period.
Preferably, the calculation formula of the local loss-of-magnetization evolution model of the permanent magnet is as follows:
in the formula, B is the magnetic induction intensity of the permanent magnet under the combined action of aging and temperature demagnetization in n temperature change periods, delta BaddThe total demagnetization quantity under the combined action of aging demagnetization and temperature demagnetization in n temperature change periods.
Preferably, the S3 specifically includes the following steps:
s31: when a permanent magnet has a local loss-of-field fault, the fault characteristic frequency of the stator current when the motor operates is collected, and the calculation formula is as follows:
in the formula (f)sFor fault characteristic frequency, f1A fundamental frequency of a stator current signal is provided, p is a pole pair number, k is an integer, and k is 1,2 and 3;
s32: establishing a motor stator current signal model when the permanent magnet is in local loss of field fault according to the formula (5), wherein the calculation formula is as follows:
in the formula i1Is stator fundamental current, A1Is the fundamental component amplitude, θ1Is the initial phase angle of the fundamental wave, ifFor stator harmonic currents in the event of local loss of field failure of the permanent magnet, A2、A3Is the amplitude of the harmonic component, and is more than or equal to 0 and less than or equal to A2≈A3≤A1，A2＝A3When it is 0, it means no loss of magnetism, A2＝A3＝A1Time indicates complete loss of field, θ2And theta3Is the harmonic component phase angle, w (t) is the noise signal.
Preferably, in S4, the calculation formula of the harmonic current evolution law of the motor stator under aging demagnetization in more than one temperature change period is as follows:
in the formula ifsFor stator harmonic currents in aging demagnetization, A2sThe amplitude of the stator harmonic current under aging demagnetization;
the calculation formula of the motor stator harmonic current evolution law under temperature demagnetization in more than one temperature change period is as follows:
in the formula ifwFor stator harmonic currents under temperature demagnetization, A2wThe amplitude of the harmonic current of the stator under temperature demagnetization;
the formula for calculating the harmonic current evolution law of the motor stator under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period is as follows:
in the formula ifThe harmonic current of the stator under the combined action of aging demagnetization and temperature demagnetization.
Preferably, when the evolution law of the harmonic current of the motor stator is calculated, the local demagnetization part of the permanent magnet is regarded as a local reverse permanent magnet superposed on the original normal permanent magnet, wherein the harmonic current ifThe induced electromotive force u generated in the winding by the magnetic induction Δ B of the opposing permanent magnet and the stator winding phase resistance R are considered to beSThe ratio of the current to the current of the reverse permanent magnet is equal to the current generated by the local demagnetizing part of the permanent magnet, and the directions of the currents are opposite.
As a general technical concept, the present invention also provides a fault injector for fault injection by using the method for simulating a local loss of field fault of a permanent magnet, comprising:
the user setting module is used for receiving the fault injection time and the fault parameters set by the user and whether noise is added or not;
the permanent magnet field loss simulation module is used for performing fault simulation by adopting the fault simulation method;
and the control unit is used for performing data interaction with the user setting module and sending out a control signal, and is also used for setting injection time and fault parameters.
The invention has the following beneficial effects:
the invention provides a method for simulating local demagnetization faults of a permanent magnet and a fault injector, which comprises the steps of establishing a first relation model of magnetic induction intensity and time under the aging demagnetization of the permanent magnet according to the timeliness of the permanent magnet; establishing a second relation model of the magnetic induction intensity and the time of the permanent magnet under temperature demagnetization in more than one temperature change period according to the temperature loss characteristic of the permanent magnet; establishing a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period according to the first relation model and the second relation model; collecting stator current fault characteristic frequency when a permanent magnet local loss of excitation fault occurs in the permanent magnet motor, and establishing a motor stator current signal model under the condition of the permanent magnet local loss of excitation fault according to the stator current fault characteristic frequency and a permanent magnet local loss of excitation evolution model; establishing a relationship between the magnetic induction intensity variation and the stator harmonic current under the loss of the permanent magnet according to a motor stator current signal model, establishing a motor stator harmonic current amplitude evolution law under the respective action of aging demagnetization and temperature demagnetization and the combined action of the aging demagnetization and the temperature demagnetization in more than one temperature variation period to obtain stator harmonic current signal models under the three modes, and performing local loss of the permanent magnet fault simulation according to the stator harmonic current signal models under the three modes; the method provided by the invention realizes the simulation of the local demagnetization fault of the permanent magnet by simultaneously considering the aging demagnetization and the temperature demagnetization factors, is simple and effective, and has important significance for the permanent magnet demagnetization fault research.
The present invention will be described in further detail below with reference to the accompanying drawings.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this application, illustrate embodiments of the invention and, together with the description, serve to explain the invention and not to limit the invention. In the drawings:
FIG. 1 is a flow chart of a method for simulating a local field loss fault of a permanent magnet motor according to a preferred embodiment of the invention;
FIG. 2 is a device frame diagram of a portion of an experimental simulation platform according to a preferred embodiment of the present invention;
FIG. 3 is a graph of magnetic induction versus time B for a ferromagnetic material under temperature demagnetization according to a preferred embodiment of the present inventionfm-a t-relation curve;
FIG. 4 is the magnetic induction versus time | B of a permanent magnet in accordance with a preferred embodiment of the present inventionfmThe i-t relationship and its upper envelope Bw-a schematic diagram of the t-curve;
FIG. 5 is a graph of permanent magnet flux density loss over a single temperature change cycle in accordance with a preferred embodiment of the present invention;
FIG. 6 is a graph of permanent magnet magnetic induction versus time over multiple temperature variation cycles in accordance with a preferred embodiment of the present invention
A relation curve;
FIG. 7 is a fault injection parameter setting interface of a preferred embodiment of the present invention;
fig. 8 is a time domain waveform of three-phase stator current of a local demagnetization permanent magnet motor under the combined action of aging demagnetization and temperature demagnetization according to the preferred embodiment of the invention;
fig. 9 is a graph of a stator current spectrum of a local demagnetized permanent magnet motor phase a under the combined action of aging demagnetization and temperature demagnetization according to the preferred embodiment of the invention.
Detailed Description
The embodiments of the invention will be described in detail below with reference to the drawings, but the invention can be implemented in many different ways as defined and covered by the claims.
Unless otherwise defined, all terms of art used hereinafter have the same meaning as commonly understood by one of ordinary skill in the art. The use of "first," "second," and similar terms in the description and in the claims of the present application do not denote any order, quantity, or importance, but rather the intention is to distinguish one element from another. Also, the use of the terms "a" or "an" and the like do not denote a limitation of quantity, but rather denote the presence of at least one.
Example 1
Referring to fig. 1, the present embodiment provides a method for simulating a local field loss fault of a permanent magnet, including the following steps:
s1: establishing a first relation model of the magnetic induction intensity and the time under the aging demagnetization of the permanent magnet according to the timeliness of the permanent magnet; establishing a second relation model of the magnetic induction intensity and the time of the permanent magnet under temperature demagnetization in more than one temperature change period according to the temperature loss characteristic of the permanent magnet;
s2: establishing a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period according to the first relation model and the second relation model;
s3: collecting stator current fault characteristic frequency when a permanent magnet local loss of excitation fault occurs in the permanent magnet motor, and establishing a motor stator current signal model under the condition of the permanent magnet local loss of excitation fault according to the stator current fault characteristic frequency and a permanent magnet local loss of excitation evolution model;
s4: the method comprises the steps of establishing a relationship between the magnetic induction intensity variation and the stator harmonic current under the condition of permanent magnet demagnetization according to a motor stator current signal model, establishing a motor stator harmonic current amplitude evolution law under the respective action of aging demagnetization and temperature demagnetization and the combined action of the aging demagnetization and the temperature demagnetization in more than one temperature variation period to obtain stator harmonic current signal models under the three modes, and carrying out local demagnetization fault simulation on the permanent magnet according to the stator harmonic current signal models under the three modes.
According to the method for simulating the local demagnetization fault of the permanent magnet, the aging demagnetization and temperature demagnetization factors are considered at the same time to realize the simulation of the local demagnetization fault of the permanent magnet, and the method is simple and effective and has important significance for the research of the local demagnetization fault of the permanent magnet.
Specifically, the embodiment is described in an environment of Simulink software of a virtual simulation platform, and as shown in fig. 2, the simulation platform includes a power supply, an inverter, a permanent magnet synchronous motor, a control circuit, a fault injector, and the like. The permanent magnet synchronous motor part parameters are shown in table 1.
TABLE 1 partial experimental parameters of PMSM
In practical application, the embodiment of the present invention may further add the following steps to optimize:
s11: the magnetic flux loss of the permanent magnet along with time is approximately in a linear relation with the elapsed time, a first relation model of the magnetic induction intensity and the time under the aging demagnetization of the permanent magnet is established, and the calculation formula is as follows:
Bs＝B0-k1t； (1)
in the formula, BsFor the magnetic induction of permanent magnets under aging demagnetization, B0Is the initial magnetic induction of the permanent magnet, k1Is an aging demagnetization factor, t is time, where k is1The size of (2) reflects the aging demagnetization rate of the permanent magnet and is related to the permanent magnet material.
S12: establishing the relationship between the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet, wherein the calculation formula is as follows:
in the formula, BwIs the magnetic induction of the permanent magnet under temperature demagnetization, k2Is a temperature demagnetization factor; it is largeThe temperature demagnetization rate of the permanent magnet is small and is obtained through an actual demagnetization data fitting curve.
Establishing a second relation model of the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet in more than one temperature change period, wherein the calculation formula is as follows:
in the formula (I), the compound is shown in the specification,
the magnetic induction intensity of the permanent magnet under temperature demagnetization in n temperature change periods,
the initial working temperature T is the jth repeated work0The corresponding initial magnetic induction intensity is obtained,
for the jth repeated working temperature T1The corresponding magnetic induction, j is 1,2, …, n, n is the total number of repeated work; t is tj-1，jFor the jth repeated working temperature T1Corresponding time, and tj-1＜tj-1，j＜tj，k3Is the magnetic flux rise factor in a single period;
further, according to the aging demagnetization and temperature demagnetization change rule of the permanent magnet, a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization in a plurality of (more than one) temperature change periods is established, and the method specifically comprises the following steps:
obtaining the aging demagnetization delta B in a plurality of temperature change periods by the formula (1)sThe formula is as follows:
obtaining the temperature demagnetization delta B in a plurality of temperature change periods according to the formula (3)wThe formula is as follows:
calculating the total demagnetization quantity delta B under the combined action of aging demagnetization and temperature demagnetization in a plurality of temperature change periodsaddThe calculation formula is as follows:
obtaining a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization, wherein the formula is as follows:
in the formula, B is the magnetic induction intensity of the permanent magnet under the combined action of aging and temperature demagnetization in a plurality of temperature change periods.
It should be noted that, in this embodiment, before establishing the second relationship model between the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet in more than one temperature change period, the method further includes the steps of: establishing a relation curve of the permanent magnet magnetic induction intensity and time under temperature demagnetization in more than one temperature change period
Relation curve
And calculating according to the irreversible demagnetization quantity in each temperature change period. Preferably, in this embodiment, a curve B of the relationship between the magnetic induction intensity of the ferromagnetic material under temperature demagnetization and time is first constructedfmT, as shown in FIG. 3, the negative part of the curve is completely changed into a positive curve, and the magnetic induction intensity of the permanent magnet under temperature demagnetization and | B of the time are plottedfmI-t relation (| B)fmL is BfmAbsolute value of). B plotted by formula (2)w-t curve is said | BfnThe upper envelope of the i-t relationship, as shown in FIG. 4, is plotted using equation (3)
Curve along said Bw-a sawtooth curve with a decreasing t-curve.
In particular, the magnetic induction of the permanent magnet is dependent on time under temperature demagnetization over a plurality of temperature change periods
The relationship curve is obtained by the following steps:
firstly, calculating the irreversible demagnetization quantity of the permanent magnet in a single temperature change period; the relationship between the magnetic induction intensity of the permanent magnetic material and the working temperature is as follows:
Br(Tw)＝Br(Tc)(1+α1(Tw-Tc)+α2(Tw-Tc)2)； (8)
in the formula, Br(Tw) Is the magnetic induction of the permanent-magnet material at operating temperature, Br(Tc) As the magnetic induction of the permanent-magnet material at the reference temperature, TwTo the operating temperature, TcFor reference temperature α1、α2The first order and second order temperature difference coefficients are respectively, and are abnormal numbers.
The working temperature range of the permanent magnet motor in a single temperature change period is assumed to be T0，T1]The temperature T is calculated according to the formula (7)0Corresponding to Br(T0) Temperature T1Corresponding to Br(T1) When the temperature is from T0Is raised to T1When, Br(T0) Gradually decreases to B along the demagnetization curver(T1) When the temperature is from T1Falls back to T0Time, magnetic induction Br(T1) Rise back to B 'along another curve'r(T0) Instead of Br(T0) And B isr(T1)＜B′r(T0)＜Br(T0) As shown in fig. 5 below; within a single temperature variation period (temperature by T)0Is raised to T1From T1Falls back to T0) The magnetic induction intensity generates irreversible loss, the irreversible loss causes irreversible demagnetization of the permanent magnet, and the calculation formula of the irreversible demagnetization quantity is as follows:
IL＝Br(T0)-B′r(T0)； (9)
in the formula, Br(T0) For a single period of temperature variation T0，T1]Internal initial operating temperature T0Corresponding initial magnetic induction, B'r(T0) For a single period of temperature variation T0，T1]Inner by T0Is raised to T1Again from T1Falls back to T0The magnetic induction intensity corresponding to the time;
further establishing magnetic induction intensity and time of permanent magnet in more than one temperature change period
A relation curve;
assuming that the temperature range of each repeated work of the permanent magnet is T0，T1]The time of each repeated work is delta t; considering irreversible demagnetization, the irreversible demagnetization quantity IL of the permanent magnet when the j time of repeated workjThe formula is as follows:
in the formula (I), the compound is shown in the specification,
represents the initial working temperature T of the j-th repeated work0The corresponding initial magnetic induction intensity is obtained,
indicates the j-th repeated operation by T0Is raised to T1(this time is denoted by t(j-1)jFor example, the operating temperature is first determined by T0Is raised to T1Corresponding to the time t01) Again from T1Falls back to T0The magnetic induction intensity that corresponds during the time, and have:
j is 1,2, …, n, n is the total number of repeated work, and the initial time is tj-1The start of the meter, the working time is tj＝tj-1+ Δ t ═ j · Δ t; when j is equal to 1, the value of j,
is the initial magnetic induction of the permanent magnet with initial time t 00, working time t1＝t0+Δt＝Δt，t01The time corresponds to the 1 st working temperature T1(ii) a When the j is 2, the sum of the j,
initial time from t1The start of the meter, the working time is t2＝t1+Δt＝2Δt，t12At the moment corresponding to the 2 nd working temperature T1(ii) a When j is 3
Initial time from t2The start of the meter, the working time is t3＝t2+Δt＝3Δt，t23The time corresponds to the 3 rd working temperature T1(ii) a …, respectively; and so on;
drawing n times of repeated work (t within n temperature change periods) of the permanent magnet according to the formula (3), the formula (8) and the formula (10)nN.Δ t) magnetic induction versus time
A relation curve, i.e. along said BwThe-t curve falls on a sawtooth curve as shown in FIG. 6 below.
When the permanent magnet has local magnetic loss fault, the fault characteristic frequency exists in the stator current when the motor runs:
in the formula，fsFor fault characteristic frequency, f1The fundamental frequency of the stator current signal is shown, and p is the pole pair number; k is an integer, k being 1,2,3.
A motor stator current signal model during the local loss of field fault of the permanent magnet is established according to a formula (10), and the calculation formula is as follows:
in the formula i1Is stator fundamental current, i1＝A1cos(2πf1t+θ1)，A1Representing the magnitude of the fundamental component, θ1Is the initial phase angle of the fundamental wave; i.e. ifIn order to generate stator harmonic current when the local loss of field fault of the permanent magnet occurs,
A2、A3representing the amplitude of the harmonic component, the amplitude reflects the severity of the loss-of-magnetization fault, and A is more than or equal to 02≈A3≤A1，A2＝A3When it is 0, it means no loss of magnetism, A2＝A3＝A1Time indicates complete loss of field, θ2And theta3Is the harmonic component phase angle; w (t) is a noise signal.
Respectively establishing a motor stator harmonic current evolution law under aging demagnetization and temperature demagnetization in a plurality of temperature change periods, wherein formulas are as follows:
in the formula ifsFor stator harmonic currents in aging demagnetization, A2sThe amplitude of the stator harmonic current under aging demagnetization;
in the formula ifwFor stator harmonic currents under temperature demagnetization, A2wFor stator harmonic current amplitude under temperature demagnetizationValue step 3: establishing a motor stator harmonic current evolution law under the combined action of aging demagnetization and temperature demagnetization in a plurality of temperature change periods, wherein the formula is as follows:
the formula for calculating the harmonic current evolution law of the motor stator under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period is as follows:
in this embodiment, the stator harmonic current evolution law is obtained by the following steps:
the local demagnetizing part of the permanent magnet is regarded as a local reverse permanent magnet superposed on the original normal permanent magnet, and the harmonic current ifCorresponding to the induced electromotive force u generated in the winding by the magnetic induction Delta B of the reverse permanent magnet (namely the magnetic induction variation under the loss of the permanent magnet) and the phase resistance R of the stator windingSThe current of the reverse permanent magnet is equal to the current generated by the local demagnetizing part of the permanent magnet, the reverse directions are equal to each other, and the directions are opposite to each other, and are expressed as follows:
in the formula, N is the number of turns of the winding coil, l is the effective length of the coil cutting magnetic field, and v is the linear velocity of the coil cutting magnetic field.
From the equation (16), it can be seen that the harmonic current i is obtained when the motor rotation speed is constantfAmplitude of (I)fmAnd the amplitude U of the induced electromotive force UmAnd the magnetic induction intensity variation delta B is in a direct proportion relation, namely:
Ifm∝Um∝ΔB；(17)
in the formula IfmAnd A in the formula (12)2、A3Corresponds to, Ifm＝A2＝A3。
Combining the formula (4) and the formula (17), obtaining the motor stator harmonic current amplitude evolution law under aging demagnetization in a plurality of temperature change periods, and expressing as follows:
combining formula (5) and formula (17), obtaining the motor stator harmonic current amplitude evolution law under temperature demagnetization in a plurality of temperature change periods, wherein the calculation formula is as follows:
thus, there are obtained:
A2＝A2s+A2w＝A3；(20)
obtaining stator harmonic current signal models under aging demagnetization and temperature demagnetization respectively according to a formula (18) and a formula (19), namely a formula (13) and a formula (14);
as a switchable embodiment, the harmonic current i of the motor stator under the combined action of aging demagnetization and temperature demagnetizationfFor stator harmonic currents i under the action of bothfsAnd ifwAdding, or calculating A from equation (20)2Then get i againfTherefore, a harmonic current signal model of the motor stator under the combined action of aging demagnetization and temperature demagnetization in a plurality of temperature change periods is obtained, as shown in formula (15) in the embodiment.
Example 2
Correspondingly to the method embodiment, the present embodiment provides a fault injector for fault injection by using the method for simulating a local loss of field fault of a permanent magnet, including:
the user setting module is used for receiving the fault injection time and the fault parameters set by the user and whether noise is added or not;
the permanent magnet field loss simulation module is used for performing fault simulation by adopting the fault simulation method;
and the control unit is used for performing data interaction with the user setting module and sending out a control signal, and is also used for setting injection time and fault parameters.
Specifically, when three kinds of local magnetic loss fault injection are implemented, the parameters of a fault injector are respectively set according to a formula (1), a formula (2) and a formula (7); respectively generating motor stator harmonic current i according to a formula (13), a formula (14) and a formula (15)fs、ifw、ifAt the set fault injection time, i is respectively setfs、ifw、ifThe normal stator current signal i is superposed to the permanent magnet motor in a signal superposition mode1And three local demagnetization faults of aging demagnetization and temperature demagnetization in a plurality of temperature change periods and consideration of combined action of the aging demagnetization and the temperature demagnetization are respectively simulated.
In this embodiment, B is set according to the initial magnetic induction of the common neodymium iron boron material of the permanent magnet motor01.35T; setting a failure demagnetization factor k according to a general value rule of a life acceleration test1＝0.05，k2When the fault is not detected, the fault injection time is set to be 1s, and the fault injection time is set to be 0.5. FIG. 7 is a fault injection parameter setting interface; fig. 8 is a time domain waveform diagram of three-phase currents of a stator of a permanent magnet synchronous motor under the combined action of aging demagnetization and temperature demagnetization in the embodiment; FIG. 9 is a frequency spectrum diagram of the A-phase stator current of the PMSM according to the present embodiment, wherein the frequency spectrum diagram is shown in
Obvious harmonic components appear at the position, so that the loss of field fault simulation of the permanent magnet synchronous motor is realized.
The result shows that the method for simulating the local field loss fault of the permanent magnet motor is simple and effective, and has important significance for the field loss fault research of the permanent magnet synchronous motor.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (7)
1. A method for simulating local loss of field fault of a permanent magnet is characterized by comprising the following steps:
s1: establishing a first relation model of the magnetic induction intensity and the time under the aging demagnetization of the permanent magnet according to the timeliness of the permanent magnet; establishing a second relation model of the magnetic induction intensity and the time of the permanent magnet under temperature demagnetization in more than one temperature change period according to the temperature loss characteristic of the permanent magnet;
s2: establishing a local demagnetization evolution model of the permanent magnet under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period according to the first relation model and the second relation model;
s3: collecting stator current fault characteristic frequency when a permanent magnet local loss of excitation fault occurs in the permanent magnet motor, and establishing a motor stator current signal model under the condition of the permanent magnet local loss of excitation fault according to the stator current fault characteristic frequency and the permanent magnet local loss of excitation evolution model;
s4: establishing a relationship between the magnetic induction intensity variation and the stator harmonic current under the demagnetization of the permanent magnet according to the motor stator current signal model, establishing an aging demagnetization and temperature demagnetization action respectively in more than one temperature change period and a motor stator harmonic current amplitude evolution rule under the combined action of the aging demagnetization and the temperature demagnetization, obtaining a stator harmonic current signal model under the combined action of the aging demagnetization and the temperature demagnetization and under the combined action of the aging demagnetization and the temperature demagnetization, and performing local demagnetization fault simulation on the permanent magnet according to the stator harmonic current signal model under the combined action of the aging demagnetization and the temperature demagnetization and the aging demagnetization under the combined action of the aging demagnetization and the temperature demagnetization in more than one temperature change period;
when the evolution law of the stator harmonic current of the motor is calculated, the local field loss part of the permanent magnet is regarded as a local reverse permanent magnet which is superposed on the original normal permanent magnet, wherein the harmonic current is regarded as generated by the ratio of the induced electromotive force generated by the magnetic induction intensity of the reverse permanent magnet in a winding to the phase resistance of the stator winding, and the current of the reverse permanent magnet is equal to the current generated by the local field loss part of the permanent magnet in magnitude and opposite in direction.
2. The method for simulating the local loss of field fault of the permanent magnet according to claim 1, wherein the step S1 specifically includes the following steps:
s11: the magnetic flux loss of the permanent magnet along with time is approximately in a linear relation with the elapsed time, a first relation model of the magnetic induction intensity and the time under the aging demagnetization of the permanent magnet is established, and the calculation formula is as follows:
Bs＝B0-k1t； (1)
in the formula, BsFor the magnetic induction of permanent magnets under aging demagnetization, B0Is the initial magnetic induction of the permanent magnet, k1Is an aging demagnetization factor, and t is time;
s12: establishing the relationship between the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet, wherein the calculation formula is as follows:
in the formula, BwIs the magnetic induction of the permanent magnet under temperature demagnetization, k2Is a temperature demagnetization factor;
establishing a second relation model of the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet in more than one temperature change period, wherein the calculation formula is as follows:
in the formula (I), the compound is shown in the specification,
the magnetic induction intensity of the permanent magnet under temperature demagnetization in n temperature change periods,
the initial working temperature T is the jth repeated work0The corresponding initial magnetic induction intensity is obtained,
for the jth repeated working temperature T1The corresponding magnetic induction, j is 1,2, …, n, n is the total number of repeated work; t is tjOperating time for repeated operation, tj-1For an initial time of repeated operation, tj-1,jFor the jth repeated working temperature T1Corresponding time, and tj-1＜tj-1,j＜tj，k3Is the magnetization factor in a single cycle.
3. The method for simulating the local loss of excitation fault of the permanent magnet according to claim 2, wherein before the second relation model of the magnetic induction intensity and the time under the temperature demagnetization of the permanent magnet in more than one temperature change period is established, the method further comprises the following steps: establishing a relation curve of the permanent magnet magnetic induction intensity and time under temperature demagnetization in more than one temperature change period
Said relation curve
And calculating according to the irreversible demagnetization quantity in each temperature change period.
4. The method for simulating the local loss of excitation fault of the permanent magnet according to claim 2, wherein the calculation formula of the local loss of excitation evolution model of the permanent magnet is as follows:
in the formula, B is the magnetic induction intensity of the permanent magnet under the combined action of aging and temperature demagnetization in n temperature change periods, delta BaddThe total demagnetization quantity under the combined action of aging demagnetization and temperature demagnetization in n temperature change periods.
5. The method for simulating the local loss of field fault of the permanent magnet according to claim 2, wherein the step S3 specifically comprises the following steps:
s31: when a permanent magnet has a local loss-of-field fault, the fault characteristic frequency of the stator current when the motor operates is collected, and the calculation formula is as follows:
in the formula (f)sFor fault characteristic frequency, f1A fundamental frequency of a stator current signal is provided, p is a pole pair number, k is an integer, and k is 1,2 and 3;
s32: establishing a motor stator current signal model when the permanent magnet is in local loss of field fault according to the formula (5), wherein the calculation formula is as follows:
in the formula i1Is stator fundamental current, A1Is the fundamental component amplitude, θ1Is the initial phase angle of the fundamental wave, ifFor stator harmonic currents in the event of local loss of field failure of the permanent magnet, A2、A3Is the amplitude of the harmonic component, and is more than or equal to 0 and less than or equal to A2≈A3≤A1，A2＝A3When it is 0, it means no loss of magnetism, A2＝A3＝A1Time indicates complete loss of field, θ2And theta3Is the harmonic component phase angle, w (t) is the noise signal.
6. The method for simulating the local loss of excitation fault of the permanent magnet according to claim 5, wherein in S4, the calculation formula of the evolution law of the harmonic current of the motor stator under aging demagnetization in more than one temperature change period is as follows:
in the formula ifsFor stators under aging demagnetizationHarmonic current, A2sThe amplitude of the stator harmonic current under aging demagnetization;
the calculation formula of the motor stator harmonic current evolution law under temperature demagnetization in more than one temperature change period is as follows:
in the formula ifwFor stator harmonic currents under temperature demagnetization, A2wThe amplitude of the harmonic current of the stator under temperature demagnetization;
the formula for calculating the harmonic current evolution law of the motor stator under the combined action of aging demagnetization and temperature demagnetization in more than one temperature change period is as follows:
in the formula ifThe harmonic current of the stator under the combined action of aging demagnetization and temperature demagnetization.
7. A fault injector for fault injection by using the method for simulating local loss of field fault of permanent magnet according to any of claims 1-6, comprising:
the user setting module is used for receiving the fault injection time and the fault parameters set by the user and whether noise is added or not;
the permanent magnet field loss simulation module is used for performing fault simulation by adopting the fault simulation method;
and the control unit is used for performing data interaction with the user setting module and sending out a control signal, and is also used for setting injection time and fault parameters.
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