CN103487718B - A kind of method of permagnetic synchronous motor interturn short-circuit failure diagnosing - Google Patents

Abstract

The invention discloses a kind of method of permagnetic synchronous motor interturn short-circuit failure diagnosing, for solving the test problems of permanent-magnetic synchronous motor stator winding interturn short-circuit fault.Its technical scheme is: first utilize the amplitude of third harmonic and the initial phase of three-phase phase current first-harmonic in fundamental voltage amplitude and initial phase in coordinate transform theory calculate residual voltage, residual voltage.Secondly, judge whether to occur shorted-turn fault: if Fs & is gt; , then there is shorted-turn fault in thr, and failure judgement phase; Otherwise, not there is shorted-turn fault.Finally, failure judgement phase: when turn-to-turn short circuit, differs from failure judgement phase according to the initial phase of first-harmonic in residual voltage and the initial phase of three-phase phase current first-harmonic.The present invention calculates simply, is easy to realize, and can diagnose shorted-turn fault in real time, and can improve the sensitivity of fault diagnosis.

Description

A kind of method of permagnetic synchronous motor interturn short-circuit failure diagnosing

Technical field

The invention belongs to fault diagnosis technology field, especially a kind of method of permagnetic synchronous motor interturn short-circuit failure diagnosing.

Background technology

Permagnetic synchronous motor (Permanentmagnetsynchronousmachine, PMSM) has the advantages such as power density is high, efficiency is high, torque ratio of inertias large, speed-regulating range width.In recent years, get the attention in the occasion such as electric automobile and wind-power electricity generation and use.

Permagnetic synchronous motor is made up of the electrical systems such as stator, rotor and bearing and mechanical system.During machine operation, have complicated energy converting between mechanical process, in long-time running, by the impact of electric power thus supplied, load behavior and running environment, some parts can lose efficacy gradually or damage.Common fault mode has that motor oscillating is excessive, motor overheating, bearing running hot, rotor/stator coil short etc.In all faults of motor, the failure rate of bearing is 40%, and the failure rate of stator is 38%, and the failure rate of rotor is 10%, and other faults account for 12%.In stator winding faults, the most common with stator winding inter-turn short circuit failure, the stator winding generation turn-to-turn short circuit of motor can produce a large amount of eddy current in short-circuit loop, if this fault is not detected, fault will increase the weight of, and will cause ground short circuit or short circuit between phase and phase, and the temperature of motor is constantly increased, finally cause motor to damage completely, therefore need the shorted-turn fault diagnosing permagnetic synchronous motor in time.

At present, proposed certain methods to diagnose the shorted-turn fault of permagnetic synchronous motor, wherein most popular method is the analytical approach etc. based on stator current signal.Conventional signal analysis technology has Fast Fourier Transform (FFT) (FastFourierTransform, FFT), Short Time Fourier Transform (Short-TimeFourierTransform, STFT), Wigner-Ville distribution (Wigner-VilleDistribution, WVD), wavelet transformation, empirical mode decomposition (EmpiricalModeDistribution, EMD) and order ratio analysis etc.But this method for diagnosing faults exists certain deficiency, the remolding sensitivity of current signal is poor on the one hand, and the calculated amount of these signal analysis technologies is larger on the other hand, not easily realizes fault diagnosis in real time.In addition, this interturn short-circuit failure diagnosing method, can only diagnose shorted-turn fault, can not judge fault phase.

Patent content

Goal of the invention: in order to overcome the deficiencies in the prior art, the invention provides a kind of method of permagnetic synchronous motor interturn short-circuit failure diagnosing, and the method calculates simple, is easy to realize, can diagnoses shorted-turn fault in real time; The method can not only diagnose shorted-turn fault, and can also failure judgement phase; The method can improve the sensitivity of fault diagnosis.

Technical scheme: for achieving the above object, the scheme that the present invention adopts is:

A method for permagnetic synchronous motor interturn short-circuit failure diagnosing, comprises the steps:

(1) coordinate transform theory calculate residual voltage V is utilized _{0, m}middle fundamental voltage amplitude V ₁with initial phase θ ₁, residual voltage V _{0, m}the amplitude V of middle third harmonic ₃, the initial phase θ of three-phase phase current first-harmonic _a, θ _b, θ _cwith residual voltage V _{0, m}the initial phase difference δ of first-harmonic in the initial phase of middle first-harmonic and A phase current;

(2) judge whether to occur shorted-turn fault: if residual voltage V _{0, m}middle fundamental voltage amplitude V ₁with residual voltage V _{0, m}the amplitude V of middle third harmonic ₃ratio Fs be greater than first threshold thr, namely then there is shorted-turn fault, and failure judgement phase; Otherwise, not there is shorted-turn fault;

(3) failure judgement phase: when turn-to-turn short circuit, according to residual voltage V _{0, m}the difference of the initial phase of middle first-harmonic and the initial phase of three-phase phase current first-harmonic carrys out failure judgement phase.If | θ ₁-δ-θ _a| < θ _thr, then A phase winding generation turn-to-turn short circuit, i.e. FlagA=1; If | θ ₁-δ-θ _b| < θ _thr, then B phase winding generation turn-to-turn short circuit, i.e. FlagB=1; Otherwise, C phase winding generation turn-to-turn short circuit, i.e. FlagC=1, wherein θ _thrfor Second Threshold.

In described step (1), utilize coordinate transform theory calculate amplitude and initial phase, its method is:

To calculate residual voltage V _{0, m}middle fundamental voltage amplitude and initial phase are example.Conveniently analyze, only consider first-harmonic and third harmonic herein, suppose residual voltage V in case of a fault _{0, m}be expressed as

In formula: ω _sfirst-harmonic angular frequency, V ₁residual voltage V _{0, m}middle fundamental voltage amplitude, V ₃residual voltage V _{0, m}the amplitude of middle third harmonic, θ ₁the initial phase of first-harmonic and third harmonic is respectively with φ.

Utilize coordinate transform theory to convert formula (1), the voltage that can obtain d axle and q axle is

Do further computing to formula (2) can obtain

Utilize low-pass filter filtering formula (3) high frequency components, can obtain

$\left\{\begin{array}{c}{V}_{\mathrm{dl}}=\frac{1}{2}{V}_1\sin \left({\mathrm{\&theta;}}_1\right)\\ V_{\mathrm{ql}}=\frac{1}{2}{V}_1\cos \left({\mathrm{\&theta;}}_1\right)\end{array}\right.---\left(4\right)$

Can obtain according to formula (4), residual voltage V _{0, m}amplitude and the initial phase of middle first-harmonic are respectively

$\left\{\begin{array}{c}{V}_1=2\sqrt{{V_{\mathrm{dl}}}^2+{V_{\mathrm{ql}}}^2}\\ {\mathrm{\&theta;}}_1={\tan }^{-1}\left(\frac{V_{\mathrm{dl}}}{V_{\mathrm{ql}}}\right)\end{array}\right.---\left(5\right)$

Equally, the method is utilized can to calculate residual voltage V _{0, m}the amplitude of middle third harmonic and the initial phase of three-phase phase current.

A method for permagnetic synchronous motor interturn short-circuit failure diagnosing, first threshold thr and Second Threshold θ _thrdefining method be respectively:

For first threshold thr, first, under permagnetic synchronous motor normal operation, record the value of Fs at different operating point, be then set to first threshold thr, finally these threshold values set are preserved in the table, call when fault diagnosis.

For Second Threshold θ _thr, the main impact by permagnetic synchronous motor power factor angle, generally its power factor (PF) can reach more than 0.9, considers and stays certain allowance, by Second Threshold θ _thrbe set to 20.

Beneficial effect: the method for a kind of permagnetic synchronous motor interturn short-circuit failure diagnosing provided by the invention, can not only diagnose shorted-turn fault in real time, and can tracing trouble phase; In failure diagnostic process, calculated amount is little, is easy to realize inline diagnosis, can overcome the deficiency of existing diagnostic method; Improve real-time, the validity and reliability of diagnosis.

Accompanying drawing explanation

Fig. 1 is magneto turn-to-turn short circuit isoboles;

Fig. 2 is interturn short-circuit failure diagnosing method process flow diagram;

Fig. 3 is the block diagram of permagnetic synchronous motor interturn short-circuit failure diagnosing method in vector controlled situation.

Embodiment

Below in conjunction with accompanying drawing, the present invention is further described.

A method for permagnetic synchronous motor interturn short-circuit failure diagnosing, comprises the steps:

(1) coordinate transform theory calculate residual voltage V is utilized _{0, m}middle fundamental voltage amplitude V ₁with initial phase θ ₁, residual voltage V _{0, m}the amplitude V of middle third harmonic ₃, the initial phase θ of three-phase phase current first-harmonic _a, θ _b, θ _cwith residual voltage V _{0, m}the initial phase difference δ of first-harmonic in the initial phase of middle first-harmonic and A phase current;

(2) judge whether to occur shorted-turn fault: if residual voltage V _{0, m}middle fundamental voltage amplitude V ₁with residual voltage V _{0, m}the amplitude V of middle third harmonic ₃ratio Fs be greater than first threshold thr, namely then there is shorted-turn fault, and failure judgement phase; Otherwise, not there is shorted-turn fault;

(3) failure judgement phase: when turn-to-turn short circuit, according to residual voltage V _{0, m}the difference of the initial phase of middle first-harmonic and the initial phase of three-phase phase current first-harmonic carrys out failure judgement phase.If | θ ₁-δ-θ _a| < θ _thr, then A phase winding generation turn-to-turn short circuit, i.e. FlagA=1; If | θ ₁-δ-θ _b| < θ _thr, then B phase winding generation turn-to-turn short circuit, i.e. FlagB=1; Otherwise, C phase winding generation turn-to-turn short circuit, i.e. FlagC=1, wherein θ _thrfor Second Threshold.

There is turn-to-turn short circuit for permagnetic synchronous motor A phase (B phase and C similar) to be below described this case:

(1) according to Fig. 1, magneto is when there is shorted-turn fault in A phase, and the voltage equation of stator winding is expressed as under abc coordinate system

$\left[V_{\mathrm{sf},\mathrm{abc}}\right]=\left[R_{\mathrm{sf}}\right]\left[i_{\mathrm{sf},\mathrm{abc}}\right]+\left[L_{\mathrm{sf}}\right]\frac{d}{\mathrm{dt}}\left[i_{\mathrm{sf},\mathrm{abc}}\right]+\left[e\right]+\left[V_0\right]---\left(6\right)$

In formula: [V _{sf, abc}]=[V _av _bv _c0] ^t, [i _{sf, abc}]=[i _ai _bi _ci _f] ^t, [V ₀]=V ₀[1110] ^tfor residual voltage, $\left[R_{\mathrm{sf}}\right]=\left[\begin{array}{cccc}{R}_s& 0& 0& -\mathrm{\&mu;}{R}_s\\ 0& R_s& 0& 0\\ 0& 0& R_s& 0\\ \mathrm{\&mu;}{R}_s& 0& 0& -\mathrm{\&mu;}{R}_s-R_f\end{array}\right],\left[L_{\mathrm{sf}}\right]=\left[\begin{array}{cccc}L& M& M& -\mathrm{\&mu;L}\\ M& L& M& -\mathrm{\&mu;M}\\ M& M& L& -\mathrm{\&mu;M}\\ \mathrm{\&mu;L}& \mathrm{\&mu;M}& \mathrm{\&mu;M}& -{\mathrm{\&mu;}}^{2}L\end{array}\right],$ $\left[e\right]=\frac{d}{\mathrm{dt}}\left[\begin{array}{c}{\mathrm{\&lambda;}}_{\mathrm{PM},a}\\ {\mathrm{\&lambda;}}_{\mathrm{PM},b}\\ {\mathrm{\&lambda;}}_{\mathrm{PM},c}\\ {\mathrm{\&lambda;}}_{\mathrm{PM},f}\end{array}\right],$ μ is A phase winding short circuit turn ratio, i _fshort-circuit loop electric current, R _fshort-circuit resistance, R _sbe stator resistance, L is self-induction, and M is mutual inductance, λ _{pM, a}, λ _{pM, b}, λ _{pM, c}, λ _{pM, f}be the permanent magnet flux linkage of A, B, C three-phase windings and short-circuit loop respectively, it is expressed as

$\left\{\begin{array}{c}{\mathrm{\&lambda;}}_{\mathrm{PM},a}={\mathrm{\&lambda;}}_{\mathrm{PM},1}\cos \left(\mathrm{\&theta;}\right)\underset{v=2k+1}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{\mathrm{PM},v}\cos (\mathrm{v\&theta;}-{\mathrm{\&theta;}}_v)\\ {\mathrm{\&lambda;}}_{\mathrm{PM},b}={\mathrm{\&lambda;}}_{\mathrm{PM},1}\cos (\mathrm{\&theta;}-\frac{2\mathrm{\&pi;}}{3})+\underset{v=2k+1}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{\mathrm{PM},y}\cos (\mathrm{v\&theta;}-{\mathrm{\&theta;}}_v-2v\frac{\mathrm{\&pi;}}{3})\\ {\mathrm{\&lambda;}}_{\mathrm{PM},c}={\mathrm{\&lambda;}}_{\mathrm{PM},1}\cos (\mathrm{\&theta;}+\frac{\mathrm{\&pi;}}{3})+\underset{v=2k+1}{\mathrm{\&Sigma;}}{\mathrm{\&lambda;}}_{\mathrm{PM},v}\cos (\mathrm{v\&theta;}-{\mathrm{\&theta;}}_v+2v\frac{\mathrm{\&pi;}}{3})\\ {\mathrm{\&lambda;}}_{\mathrm{PM},f}=\mathrm{\&mu;}{\mathrm{\&lambda;}}_{\mathrm{PM},a}\end{array}\right.---\left(7\right)$

In formula: λ _{pM, 1}be the amplitude of first-harmonic magnetic linkage, v is overtone order, λ _{pM, v}be the amplitude of v subharmonic magnetic linkage, θ is rotor electrical angle, θ _vit is the angle between v subharmonic magnetic linkage and first-harmonic magnetic linkage.

Formula (7) substituted into (6) and does computing, can obtain

$V_0=\frac{1}{3}(V_a+V_b+V_c)-\frac{1}{3}{R}_{\mathrm{add}}{i}_a+\frac{1}{3}\mathrm{\&mu;}{R}_s{i}_f+\frac{1}{3}\mathrm{\&mu;}(L+2M)\frac{{\mathrm{di}}_f}{\mathrm{dt}}-\frac{{\mathrm{d\&lambda;}}_{\mathrm{PM},0}}{\mathrm{dt}}---\left(8\right)$

In formula: λ _{pM, 0}=(λ _{pM, a}+ λ _{pM, b}+ λ _{pM, c})/3 are stator zero sequence permanent magnet flux linkage.

According to Fig. 1, the electric current sum flowing through three balance resistances is zero, namely

$\frac{V_a-V_{0,c}}{R}+\frac{V_b-V_{0,c}}{R}+\frac{V_c-V_{0,c}}{R}=0---\left(9\right)$

According to formula (9), can obtain

$V_{0,c}=\frac{1}{3}(V_a+V_b+V_c)---\left(10\right)$

According to Fig. 1

V ₀=V _0,c+V _0,m（11）

According to formula (8), (10) and (11), can obtain

$V_{0,m}=\frac{1}{3}\mathrm{\&mu;}{R}_s{i}_f+\frac{1}{3}\mathrm{\&mu;}(L+2M)\frac{{\mathrm{di}}_f}{\mathrm{dt}}-\frac{{\mathrm{d\&lambda;}}_{\mathrm{PM},0}}{\mathrm{dt}}---\left(12\right)$

As can be seen from formula (12), utilize balance resistance can make residual voltage V _{0, m}not by the impact of transducer, only by the impact of motor itself.Known according to formula (12), at PMSM under normal circumstances, i _fbe 0, residual voltage V _{0, m}only depend on λ _{pM, 0}differential.Therefore, residual voltage V _{0, m}in only have third harmonic and its odd-multiple subharmonic.But, when shorted-turn fault appears in PMSM, residual voltage V _{0, m}not only by λ _{pM, 0}the impact of differential, more importantly by short-circuit current i _fimpact.In this case, residual voltage V _{0, m}in except having third harmonic and its odd-multiple subharmonic, also have the first-harmonic that amplitude is larger, and 5 times and 7 inferior odd harmonics etc.Therefore, residual voltage V can be utilized _{0, m}first-harmonic become assign to diagnose shorted-turn fault.

(2) short-circuit current i _f

Ignore higher hamonic wave, short-circuit current i _fbe expressed as

i _f=I _fsin(ω _st+φ)（13）

In formula: I _fthe amplitude of short-circuit current, being the initial phase of short-circuit current, is determined by the equal factor of the fault occurred.The present invention considers that shorted-turn fault occurs Α phase, therefore, in the ideal case, substantially be consistent with the initial phase of Α phase current.

Formula (13) is substituted into formula (12) can obtain

$\begin{array}{c}{V}_{0,m}=\frac{1}{3}\mathrm{\&mu;}{R}_s{I}_f\sin ({\mathrm{\&omega;}}_{s}t+\mathrm{\&phi;})+\frac{1}{3}\mathrm{\&mu;}{\mathrm{\&omega;}}_s{I}_f(L+2M)\cos ({\mathrm{\&omega;}}_{s}t+\mathrm{\&phi;})-\frac{d{\mathrm{\&lambda;}}_{\mathrm{PM},0}}{\mathrm{dt}}\\ =A\sin ({\mathrm{\&omega;}}_{s}t+\mathrm{\&phi;}+\mathrm{\&delta;})-\frac{{d\mathrm{\&lambda;}}_{\mathrm{PM},0}}{\mathrm{dt}}\end{array}---\left(14\right)$

In formula: $A=\sqrt{{\left(\frac{1}{3}\mathrm{\&mu;}{R}_s{I}_f\right)}^2+{\left(\frac{1}{3}\mathrm{\&mu;}{\mathrm{\&omega;}}_s{I}_f(L+2M)\right)}^2},$

$\mathrm{\&delta;}={\tan }^{-1}(\frac{1}{3}\mathrm{\&mu;}{\mathrm{\&omega;}}_s{I}_f(L+2M)/\left(\frac{1}{3}\mathrm{\&mu;}{R}_s{I}_f\right))={\tan }^{-1}\left({\mathrm{\&omega;}}_s\right(L+2M)/R_s).$

Residual voltage V can be found out from formula (13) and (14) _{0, m}the difference of the initial phase of middle first-harmonic and the initial phase of short-circuit current is δ, that is to say residual voltage V _{0, m}in the initial phase of middle first-harmonic and A phase current, the initial phase difference of first-harmonic is δ.

(3) coordinate transform theory is utilized to extract residual voltage V _{0, m}the amplitude of middle first-harmonic and initial phase, residual voltage V _{0, m}the amplitude of middle third harmonic and the initial phase of three-phase phase current first-harmonic.

To calculate residual voltage V _{0, m}middle fundamental voltage amplitude and initial phase are example.Conveniently analyze, the present invention only considers first-harmonic and third harmonic, supposes residual voltage V in case of a fault _{0, m}be expressed as

In formula: ω _sfirst-harmonic angular frequency, V ₁residual voltage V _{0, m}middle fundamental voltage amplitude, V ₃residual voltage V _{0, m}the amplitude of middle third harmonic, θ ₁the initial phase of first-harmonic and third harmonic is respectively with φ.

Utilize coordinate transform theory to convert formula (15), the voltage that can obtain d axle and q axle is

Do further computing to formula (16) can obtain

Utilize low-pass filter filtering formula (17) high frequency components, can obtain

$\left\{\begin{array}{c}{V}_{\mathrm{dl}}=\frac{1}{2}{V}_1\sin \left({\mathrm{\&theta;}}_1\right)\\ V_{\mathrm{ql}}=\frac{1}{2}{V}_1\cos \left({\mathrm{\&theta;}}_1\right)\end{array}\right.---\left(18\right)$

Can obtain according to formula (18), residual voltage V _{0, m}amplitude and the initial phase of middle first-harmonic are respectively

$\left\{\begin{array}{c}{V}_1=2\sqrt{{V_{\mathrm{dl}}}^2+{V_{\mathrm{ql}}}^2}\\ {\mathrm{\&theta;}}_1={\tan }^{-1}\left(\frac{V_{\mathrm{dl}}}{V_{\mathrm{ql}}}\right)\end{array}\right.---\left(5\right)$

In addition, similar method is utilized can to extract residual voltage V _{0, m}the amplitude of middle third harmonic and the initial phase of three-phase phase current first-harmonic.

(4) method for diagnosing faults

In order to represent fault degree quantitatively, definition coefficient Fs

$\mathrm{Fs}=\frac{V_1}{V_3}---\left(20\right)$

In formula: V ₁for residual voltage V _{0, m}the amplitude of middle first-harmonic, V ₃for residual voltage V _{0, m}the amplitude of middle third harmonic.

In order to realize fault diagnosis, being divided into three steps: first, utilizing coordinate transform theory to extract residual voltage V _{0, m}the amplitude V of middle first-harmonic ₁and phase theta ₁, third harmonic amplitude V ₃with the initial phase θ of three-phase phase current first-harmonic _a, θ _b, θ _cwith residual voltage V _{0, m}the initial phase difference δ of first-harmonic in the initial phase of middle first-harmonic and A phase current.Secondly, judge whether to occur shorted-turn fault: if residual voltage V _{0, m}middle fundamental voltage amplitude V ₁with residual voltage V _{0, m}the amplitude V of middle third harmonic ₃ratio Fs be greater than first threshold thr, namely then there is shorted-turn fault, and failure judgement phase; Otherwise, not there is shorted-turn fault.Finally, failure judgement phase: when turn-to-turn short circuit, according to residual voltage V _{0, m}the difference of the initial phase of middle first-harmonic and the initial phase of three-phase phase current first-harmonic carrys out failure judgement phase.Its Troubleshooting Flowchart as shown in Figure 2, θ in figure _thrfor Second Threshold.If | θ ₁-δ-θ _a| < θ _thr, then A phase winding generation turn-to-turn short circuit, i.e. FlagA=1; If | θ ₁-δ-θ _b| < θ _thr, then B phase winding generation turn-to-turn short circuit, i.e. FlagB=1; Otherwise, C phase winding generation turn-to-turn short circuit, i.e. FlagC=1.Fig. 3 is the block diagram of permagnetic synchronous motor interturn short-circuit failure diagnosing method in vector controlled situation.

For first threshold thr, first, under permagnetic synchronous motor normal operation, record the value of Fs at different operating point, be then set to first threshold thr, finally these first threshold thr set are preserved in the table, call when fault diagnosis.For Second Threshold θ _thrdetermination, the main impact by permagnetic synchronous motor power factor angle, generally its power factor (PF) can reach more than 0.9, considers and stays certain allowance, by Second Threshold θ _thrbe set to 20.

Utilize the method that the present invention proposes, effectively can diagnose the shorted-turn fault of permagnetic synchronous motor.The present invention can not only diagnose shorted-turn fault in real time, and can tracing trouble phase; In failure diagnostic process, calculated amount is little, can overcome the deficiency of existing diagnostic method, is a kind of method for diagnosing faults that effectively can improve permagnetic synchronous motor safety, reliability.

Claims (2)

1. a method for permagnetic synchronous motor interturn short-circuit failure diagnosing, is characterized in that: steps of the method are:

(1) coordinate transform theory calculate residual voltage V is utilized _{0, m}middle fundamental voltage amplitude V ₁with initial phase θ ₁, residual voltage V _{0, m}the amplitude V of middle third harmonic ₃, the initial phase θ of three-phase phase current first-harmonic _a, θ _b, θ _cwith residual voltage V _{0, m}the initial phase difference δ of first-harmonic in the initial phase of middle first-harmonic and A phase current;

(2) judge whether to occur shorted-turn fault: if residual voltage V _{0, m}middle fundamental voltage amplitude V ₁with residual voltage V _{0, m}the amplitude V of middle third harmonic ₃ratio Fs be greater than first threshold thr, namely then there is shorted-turn fault, and failure judgement phase; Otherwise, not there is shorted-turn fault;

(3) failure judgement phase: when turn-to-turn short circuit, according to residual voltage V _{0, m}the difference of the initial phase of middle first-harmonic and the initial phase of three-phase phase current first-harmonic carrys out failure judgement phase, if | θ ₁-δ-θ _a| < θ _thr, then A phase winding generation turn-to-turn short circuit, i.e. FlagA=1; If | θ ₁-δ-θ _b| < θ _thr, then B phase winding generation turn-to-turn short circuit, i.e. FlagB=1; Otherwise, C phase winding generation turn-to-turn short circuit, i.e. FlagC=1, wherein θ _thrfor Second Threshold;

Described step (1) utilizes coordinate transform theory calculate residual voltage V _{0, m}middle fundamental voltage amplitude and initial phase, its method is:

Residual voltage V in case of a fault _{0, m}be expressed as

In formula: ω _sfirst-harmonic angular frequency, V ₁residual voltage V _{0, m}middle fundamental voltage amplitude, V ₃residual voltage V _{0, m}the amplitude of middle third harmonic, θ ₁the initial phase of first-harmonic and third harmonic is respectively with φ;

Utilize coordinate transform theory to convert formula (1), the voltage that can obtain d axle and q axle is

Do further computing to formula (2) can obtain

Utilize low-pass filter filtering formula (3) high frequency components, can obtain

$\left\{\begin{array}{c}{V}_{dl}=\frac{1}{2}{V}_1\sin \left({\mathrm{\&theta;}}_1\right)\\ V_{ql}=\frac{1}{2}{V}_1\cos \left({\mathrm{\&theta;}}_1\right)\end{array}\right.---\left(4\right)$

Can obtain according to formula (4), residual voltage V _{0, m}amplitude and the initial phase of middle first-harmonic are respectively

$\left\{\begin{array}{c}{V}_1=2\sqrt{{V_{dl}}^2+{V_{ql}}^2}\\ {\mathrm{\&theta;}}_1={\tan }^{-1}\left(\frac{V_{dl}}{V_{ql}}\right)\end{array}\right.---\left(5\right)$

Equally, the method is utilized can to calculate residual voltage V _{0, m}the amplitude of middle third harmonic and the initial phase of three-phase phase current first-harmonic.

2. the method for a kind of permagnetic synchronous motor interturn short-circuit failure diagnosing according to claim 1, is characterized in that: first threshold thr and Second Threshold θ _thrdefining method be respectively:

For first threshold thr, first, under permagnetic synchronous motor normal operation, record the value of Fs at different operating point, be then set to first threshold thr, finally these threshold values set are preserved in the table, call when fault diagnosis;

For Second Threshold θ _thr, be set to 20.