CN116243093A - Single-sensor phase current reconstruction three-phase voltage source type inverter fault diagnosis method - Google Patents
Single-sensor phase current reconstruction three-phase voltage source type inverter fault diagnosis method Download PDFInfo
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Abstract
The invention provides a fault diagnosis method for a single-sensor phase current reconstruction three-phase voltage source type inverter, which solves the problems of feasibility and diagnosis time of open-circuit fault diagnosis of the single-current sensor three-phase voltage source type inverter; the method comprises the following steps: firstly, analyzing the existence mechanism of a current unobservable area of a direct-current bus single sensor and the voltage vector synthesis mechanism under four faults of single-tube open circuit, heterogeneous same-side double-tube open circuit, heterogeneous different-side double-tube open circuit and in-phase double-tube open circuit; then, two complementary effective voltage vectors replace zero vectors, so that reliable reconstruction of fault phase current in a current invisible area is realized; finally, the fault diagnosis method of the inverter, which consists of three diagnostic criteria of a current vector phase angle, an average current vector module value and a phase angle, realizes the fault diagnosis of the three-phase voltage source inverter under a single current sensor. The method realizes open-circuit fault diagnosis under single-sensor phase current reconstruction, and can effectively and rapidly locate the fault power tube.
Description
Technical Field
The invention relates to the technical field of inverter fault diagnosis, in particular to a single-sensor phase current reconstruction three-phase voltage source type inverter fault diagnosis method.
Background
The single-sensor three-phase voltage source type inverter can reduce the system cost and the volume, and can eliminate the influence of the parameter difference of multiple current sensors on the performance of a control system, but when a power switch tube of a core device works in a high-voltage and high-current state, the power switch tube is possibly broken under the influence of overvoltage or overcurrent and the influence of a heating effect, so that open-circuit faults are caused. The inverter fault diagnosis research based on single sensor phase current reconstruction is developed, the rapid diagnosis and positioning of faults are realized, and the method has important significance for improving the reliability of the inverter.
Three-phase current information is an important parameter for inverter fault diagnosis. A core problem with single sensor phase current reconstruction is to eliminate the effect of current non-observable areas. Currently available research methods include vector pulse insertion, phase shifting, complementary non-zero vector methods, and the like. The document [ Shen Yongpeng, zheng Zhufeng, yang Xiaoliang, etc. ] DC bus current sampling voltage space vector pulse width modulation [ J ]. The technical school of electrician, 2021,36 (08): 1617-1627 ] proposes a hybrid pulse width modulation method which ensures that the reconstructed current stably follows the actual current and improves the current distortion problem. Document [ GU YIKUN, NI FENGLEI, YANG DAPENG, et al, switching-state phase shift method for three-phase-current reconstruction with a single DC-link current sensor [ J ]. IEEE Transactions on Industrial Electronics,2011,58 (11): 5186-5194 ] employs a phase shifting method to increase sampling time at non-zero voltage vectors, but asymmetry in PWM waveforms in the unobservable region will cause current distortion. The document [ Shen Yongpeng, wang Qiancheng, wang Yanfeng, et al, error self-correcting hybrid pulse width modulation strategy [ J ]. Programming, 2022,37 (14): 3643-3653] proposes a hybrid modulation method of non-zero voltage vectors and traditional SVPWM, which expands the reconstruction range while reducing current distortion. The literature [ SHEN yongpen, LIU Di, LIU Pu, et al error Self-calibration of Phase Current Reconstruction Based on Random Pulse Width Modulation [ J ]. IEEE Journal ofEmerging and Selected switchable viewer in Power Electronics,2022 ] proposes a hybrid pulse width modulation method with error Self-correction function, which achieves Self-detection and Self-correction of the current zero drift amount while eliminating the current unobservable region. The literature [ Xiaofei, xu Guanda, even pass intensity, etc. ] the three-phase current reconstruction strategy of the single current sensor system of the permanent magnet synchronous motor [ J ]. The electrician technical report, 2022,37 (7): 1609-1617 ] provides a single current sensor vector control strategy based on an adaptive observer, reduces the total current harmonic and torque error, but increases the operation burden of a processing unit. The literature [ SHEN Yongpen, LIU Di, LIANG Weihua, et al Current Reconstruction of Three-phase Voltage Source Inverters Considering Current Ripple [ J ]. IEEE Transactions on Transportation Electrification,2022 ] proposes a midpoint value random space vector pulse width modulation phase current reconstruction strategy for the influence of current ripple on reconstruction accuracy, and the method does not need to insert redundant voltage vectors and a large amount of calculation, thereby improving the current reconstruction accuracy.
For a three-phase voltage source inverter, a single current sensor at the dc bus may reflect the phase current under any power switching tube fault. The traditional inverter fault diagnosis method mainly extracts phase current fault characteristic values. The literature [ CECATI C, TOMMASO AO D, GENDUSO F, et al, comprehensive Modeling and Experimental Testing of Fault Detection and Management of a Nonredundant Fault-Tolerant VSI [ J ]. IEEE Transactions on Industrial Electronics,2015,62 (6): 3945-3954 ] proposes a fault diagnosis method based on the slope of a current vector track, and the method extracts vector phase angle characteristics through a Lissajous diagram of the current vector track, thereby realizing the positioning of a fault power tube, but the detected fault type is less and has a risk of misdiagnosis. The literature [ in swimming, jiang Shengcheng, yang Rongfeng, etc. ] frequency converter IGBT open-circuit fault diagnosis method [ J ]. Chinese motor engineering report, 2011,31 (09): 30-35 ] provides a normalized inverter open-circuit fault diagnosis method based on Fourier transformation, which adopts Fourier transformation to separate direct current components and odd harmonics of single-phase current and positions fault devices according to the normalized direct current components, but is not suitable for double-power switch open-circuit fault detection. The literature [ Zhang Jianghan, zhao Jin, zhou Dehong, et al high-performance fault diagnosis in PWM voltage-source inverters for vector-controlled induction motor drives [ J ]. IEEE Transactions on Power Electronics,2014,29 (11): 6087-6099 ]) proposes a normalization method of current error combined with phase current fundamental period average value, and realizes the positioning of fault power tube by setting empirical threshold, but the diagnosis time needs more than two fundamental periods. The method for rapidly diagnosing and positioning the open-circuit fault of the inverter based on the characteristic analysis of the current vector is disclosed in the literature [ Chen Yong, liu Zhilong, chen Zhangyong ]. The technical report of electrician [ J ]. 2018,33 (04): 883-891.] according to the characteristic of the phase angle of the current vector after Park conversion, when a certain power switching tube is in fault, the scanning time of a sector where the fault is located is changed, so that the positioning of different fault positions is realized. The literature [ ESPINOZA-TREJO D R, CAMPOS-DELGADO D U, bossiog, et al fault diagnosis scheme for open-circuit faults in field-oriented control induction motor drives [ J ]. IET Power Electronics,2013,6 (5): 869-877 ] proposes a fault diagnosis method based on a nonlinear observer, and fault detection and localization are performed by using stator currents and residuals obtained by the nonlinear observer, but the diagnosis accuracy is greatly affected by the residuals. The inverter open-circuit fault diagnosis method based on a switching function model [ An Quntao, sun Li, zhao Ke, etc. ] is realized by performing a double fourier transform spectrum analysis on the direct-current side current by 2010,30 (06): 1-6 ], but the diagnosis result is affected by noise disturbance. The three-phase inverter fault diagnosis based on spectrum estimation [ Cui Bowen, chapter, technical science of electrician [ J ]. 2009,24 (11): 192-198 ] determines a fault switching element and its fault property based on spectrum estimation and a neural network, but the calculated amount is large and the real-time performance is poor. The method for diagnosing the open-circuit fault of the inverter based on the interval sliding mode observer [ Chen Chaobo, wang Xiaxia, gao Song, etc. ] is based on the theory of motor engineering in China, 2020,40 (14): 4569-4579+4736 ] estimates the current value in the normal state through the sliding mode observer, and performs fault location according to the residual errors of the actual system and the observer, thereby improving the robustness of the system, but being more sensitive to the residual error parameters.
Disclosure of Invention
Aiming at the feasibility and diagnosis time problems of open-circuit fault diagnosis of a single-current sensor three-phase voltage source type inverter, the invention provides a fault diagnosis method of the single-sensor phase current reconstruction three-phase voltage source type inverter, which comprises the steps of firstly analyzing the existence mechanism of a single-current-observable area of a direct-current bus and the voltage vector synthesis mechanism under four faults of single-tube open-circuit, heterogeneous same-side double-tube open-circuit, heterogeneous different-side double-tube open-circuit and homogeneous double-tube open-circuit; then, two complementary effective voltage vectors replace zero vectors, so that reliable reconstruction of fault phase current in a current invisible area is realized; further, an inverter fault diagnosis method composed of three diagnostic criteria including a current vector phase angle, an average current vector module value and a phase angle is constructed, and fault diagnosis of the three-phase voltage source type inverter under a single current sensor is realized.
The technical scheme of the invention is realized as follows:
a fault diagnosis method for a single-sensor phase current reconstruction three-phase voltage source type inverter comprises the following steps:
step one: analyzing the existence mechanism of a current unobservable area of a direct-current bus single sensor and a voltage vector synthesis mechanism under four types of faults, namely single-tube open circuit, heterogeneous same-side double-tube open circuit, heterogeneous different-side double-tube open circuit and in-phase double-tube open circuit;
step two: by adopting complementary non-zero vectors to replace the original zero vectors, two new sampling windows meeting the minimum sampling time are provided in the carrier period, the influence of an unobservable area is eliminated, and three-phase current reconstruction is realized;
step three: and calculating a current vector phase angle, an average current vector module value and an average current vector phase angle according to the reconstructed three-phase current, and performing fault location by taking the current vector phase angle, the average current vector module value and the average current vector phase angle as diagnosis criteria to obtain a diagnosis result.
The existence mechanism of the current unobservable area of the direct current bus single sensor is as follows: in the SVPWM modulation mode, the switching state of each phase bridge arm switching device can be controlled by a variable S p (p.epsilon. { a, b, c }) represents S when the upper arm is on p =1, S for conducting the lower arm p =0; space voltage vector u i (S a ，S b ，S c ) I e {0,1,2,3,4,5,6,7} represents 8 different switch states, including 6 effective voltage vectors and 2 zero voltage vectors; the whole working area can be divided into 6 sectors, and each sector comprises a normal area, a sector boundary and a low modulation area, wherein the normal area belongs to an observable area, and the sector boundary and the low modulation area belong to an unobservable area.
In the second step, the specific implementation method is as follows:
when referring to voltage vector u ref In the observable region, taking an example of an I sector, where the effective voltage vector u 1 、u 2 Sum zero vector time of action T 1 、T 2 and T0 The method comprises the following steps of:
wherein ,
u is a modulation degree dc Representing a DC bus voltage; t (T) s Is a carrier period; θ is the phase angle range of the target vector;
when referring to voltage vector u ref When in the unobservable region, the zero voltage vector u is calculated 0 、u 7 Instead of being complementary non-zero vectors u 3 、u 6 The action time is as follows:
in the complementary non-zero vector compensation, the synthesized voltage vector of the I sector is set as u' ref ：
u' ref T s ＝u 1 T 1 +u 2 T 2 +u 3 T 3 +u 6 T 6 ；
Due to
Synthetic vector u' ref The method meets the following conditions: u's' ref T s ＝u 1 T 1 +u 2 T 2 ＝u ref T s ；
Effective voltage vector u 1 (100) The action time satisfies the minimum sampling time T min Located in the observable area, can generate sampling points T sam1 ；u 2 (110) Does not satisfy the minimum sampling time T min Located in an unobservable region; at this time, the zero voltage vector u is calculated according to the complementary non-zero vector compensation principle 0 、u 7 Replacement by complementary non-zero vector u 3 、u 6 The action time is T 0 2, and in u 6 Current sampling is carried out during the action, and the sampling point is T sam2 ；T sam1 and Tsam2 Obtaining phase A and phase C currents i respectively are 、-i bre Thereby realizing three-phase current reconstruction.
The minimum sampling time T min The expression of (2) is:
T min ＝T on +T db +T rise +T sr +T con ；
wherein ,Ton For switching device on time, T db For PWM dead time, T con For AD conversion time, T rise In order to sample the circuit current rise time,T sr is the slew rate of the operational amplifier voltage.
The method for calculating the current vector phase angle, the average current vector module value and the average current vector phase angle according to the reconstructed three-phase current comprises the following steps:
reconstructing three-phase current i are 、i bre 、i cre Two-phase components in the alpha beta coordinate system can be obtained through Park transformation:
wherein ,iα Representing the alpha-axis current component, i, after Park conversion β Representing the beta-axis current component after Park conversion; i represents i α and iβ A composite current vector in a two-phase coordinate system;
i α 、i β average current vector over 1 cycle
The average current vector synthesis formula is:
wherein v=α, β, i v (N) represents a current vector, N represents a summation start value, N represents a summation end value, N * Is the number of current samples in a1 cycle,
is the alpha-axis average current component; />
Is the beta-axis average current component; />
Is the average current vector after synthesis;
the current vector phase can be obtained by inverse trigonometric functionCorner angle
Average current vector modulus>
And average current vector phase angle
The method comprises the following steps of:
when the three-phase voltage source type inverter works normally in steady state, i is converted by Park α and iβ The resultant current vector i in the two-phase coordinate system rotates in a circular trajectory, i.e
Two-phase current i α and iβ Average current vector in any period +.>
Is 0; when an open circuit fault occurs in a single or two power switching tubes, the motion trail of a current vector i is changed and the average current vector +.>
Is +.>
Phase angle->
Not constantly 0.
The method for obtaining the diagnosis result by using the current vector phase angle, the average current vector module value and the average current vector phase angle as diagnosis criteria for fault location comprises the following steps:
calculating the phase angle of the current vector i
By comparison->
And->
Judging the motion trail;
calculating an average current vector
Is +.>
Phase angle>
By comparison->
And->
And->
Locating a fault position; />
Output fault location variable S dio Obtaining a diagnosis result;
wherein ,
for the current vector phase angle threshold, k=1, 2, < ->
For the average current vector modulus threshold, k' =1, 2,3, ++>
Is the average current vector phase angle threshold, p is the fault location, S dio For locating the variable for the fault, S dio The tens and units of the number of (2) correspond to the fault positions respectively.
Compared with the prior art, the invention has the beneficial effects that:
1) The invention adopts two complementary effective non-zero vectors to replace zero vectors, thereby ensuring that the current sampling time at the DC bus is longer than T min Reliable reconstruction of fault phase current in the current invisible area is realized.
2) The invention adopts the inverter fault diagnosis method with the current vector phase angle, the average current vector module value and the phase angle as diagnosis criteria, and the diagnosis time is 0.5ms, thereby realizing the rapid positioning of the fault power tube.
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In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a block diagram of a three-phase voltage source inverter dc bus single current sensor system of the present invention.
Fig. 2 shows space voltage vectors and distribution diagrams of regions according to the present invention.
Fig. 3 is a schematic diagram of normal region phase current sampling and reconstruction in accordance with the present invention.
FIG. 4 is a diagram of the invention S 2 Voltage vector analysis under faults; (a) Is u 3 (010) Current flow diagram under action, (b) is u 3 (010) Current flow diagram under action, (c) is u 3S2 (010) Vector composite map, (d) is u 5S2 (001) Vector composite map, (e) is S 2 Voltage vector distribution map under fault.
FIG. 5 is S of the present invention 1 S 3 Voltage vector analysis under faults; (a) Is u 4 (011) Current flow diagram under action, (b) isu 6 (101) Current flow diagram under action, (c) is u 4S13 (011) Vector composite map, (d) is u 6S13 (101) Vector composite map, (e) is S 1 S 3 Voltage vector distribution map under fault.
FIG. 6 is S of the present invention 1 S 4 Voltage vector analysis under faults; (a) Is u 2 (110) Current flow diagram under action, (b) is u 5 (001) Current flow diagram under action, (c) is u 2S14 (110) Vector composite map, (d) is u 5S14 (001) Vector composite map, (e) is S 1 S 4 Voltage vector distribution map under fault.
FIG. 7 is a diagram of the invention S 1 S 2 Voltage vector analysis under faults; (a) Is u 2 (110) Current flow diagram under action, (b) is u 3 (010) Current flow diagram under action, (c) is u 5 (001) Current flow diagram under action, (d) is u 6 (101) Current flow diagram under action, (e) is u 2S12 (110) Vector composite map, (f) is u 3S12 (010) Vector composite map with (g) u 5S12 (001) Vector synthesis map, (h) is u 6S12 (101) Vector composite map, (i) is S 1 S 2 Voltage vector distribution map under fault.
Fig. 8 is a schematic diagram of complementary non-zero vector compensation of the present invention.
Fig. 9 is a graph of PWM waveforms under complementary non-zero vector compensation of the present invention.
Fig. 10 is a fault diagnosis flow chart of the present invention.
FIG. 11 is an experimental platform of the present invention.
Fig. 12 shows PWM waveforms and sampling times in the invisible area of each sector according to the present invention.
FIG. 13 is a diagram of the invention S 2 And (3) actually reconstructing a three-phase current waveform diagram under the fault condition.
FIG. 14 is a diagram of the invention S 1 S 3 And (3) actually reconstructing a three-phase current waveform diagram under the fault condition.
FIG. 15 is a diagram of the invention S 1 S 2 And (3) actually reconstructing a three-phase current waveform diagram under the fault condition.
Fig. 16 is a graph of current vectors after an open circuit fault of the present invention.
Fig. 17 is a post-fault current vector phase angle of the present invention.
FIG. 18 shows the average current vector modulus of the present invention
FIG. 19 is an average current vector phase angle of the present invention
Fig. 20 is a failure diagnosis result of the present invention.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without any inventive effort, are intended to be within the scope of the invention.
The embodiment of the invention provides a fault diagnosis method for a single-sensor phase current reconstruction three-phase voltage source type inverter, which solves the problems of feasibility and diagnosis time of open-circuit fault diagnosis of the single-current sensor three-phase voltage source type inverter; the method comprises the following steps: firstly, analyzing the existence mechanism of a current unobservable area of a direct-current bus single sensor and the voltage vector synthesis mechanism under four types of faults, namely single-tube open circuit, heterogeneous same-side double-tube open circuit, heterogeneous different-side double-tube open circuit and in-phase double-tube open circuit; secondly, by adopting complementary non-zero vectors to replace the original zero vectors, two new sampling windows meeting the minimum sampling time are provided in the carrier period, the influence of an unobservable area is eliminated, and three-phase current reconstruction is realized; finally, calculating a current vector phase angle, an average current vector module value and an average current vector phase angle according to the reconstructed three-phase current, and carrying out fault location by taking the three parameters as diagnostic criteria to obtain a diagnosis result; the fault diagnosis of the three-phase voltage source type inverter under the single current sensor is realized.
The phase current reconstruction system of the direct current bus single current sensor performs time-sharing acquisition on the direct current bus current information corresponding to each voltage vector in the action process in one carrier period, so that three-phase current is reconstructed, and the system structure is shown in figure 1.
Under SVPWM (Space Vector Pulse Width Modulation) modulation mode, the switching state of each phase bridge arm switching device can be controlled by variable S p (p.epsilon. { a, b, c }) represents S when the upper arm is on p =1, S for conducting the lower arm p =0. As shown in fig. 2, the space voltage vector u i (S a ，S b ，S c ) I e {0,1,2,3,4,5,6,7} represents 8 different switch states, including 6 effective voltage vectors and 2 zero voltage vectors. The entire operating area may be divided into 6 sectors, each of which includes a normal area, a sector boundary, and a low modulation area, wherein the normal area belongs to an observable area, and the sector boundary and the low modulation area belong to an unobservable area, as shown in fig. 2.
Let the carrier period be T s Taking an I sector as an example, in a normal region, the reference voltage vector u ref Can be represented by the effective voltage vector u 1 、u 2 Zero voltage vector u 0 、u 7 And (5) synthesizing. As shown in fig. 3, according to the effective voltage vector u 1 、u 2 Time of action, respectively to T sam1 and Tsam2 Direct current bus current i dc Sampling to obtain two-phase current i are and -icre Third phase current i bre Can be derived from kirchhoff's current law.
According to the method, the direct current bus current under the action of different voltage vectors of each sector is sampled, so that the sampling result shown in the table 1 can be obtained, and further, the phase current reconstruction is realized.
TABLE 1 Voltage vector and DC bus Current
In actual circuit, due to the on-time T of the switching device on PWM dead time T db The dc bus does not immediately exhibit phase currents when vector-acted. At the same time, receive AD conversion time T con Sampling circuit current rise time T rise Operational amplifier voltage slew rate T sr The bus current sampling results typically require some time to stabilize, limiting. Therefore, the minimum time required for accurately completing the acquisition of the DC bus current is defined as the minimum sampling time T min ，
T min ＝T on +T db +T rise +T sr +T con (1)
In the current invisible area such as sector boundary, low modulation area, etc., at least one effective voltage vector does not satisfy T min The current cannot be sampled accurately. Thus, the key to single sensor phase current reconstruction is to ensure that there are two or more coincident T's within each carrier period min Is provided for the different effective voltage vectors of (a).
Common open faults for a three-phase voltage source inverter include single-tube open faults, out-of-phase on-side double-tube open faults, out-of-phase off-side double-tube open faults, and in-phase double-tube open faults, for a total of 4 types of 21 fault conditions, as shown in table 2.
Table 2 inverter fault type and fault location
(1) Single tube open circuit fault
By S 2 Open circuit failure is exemplified by a b-phase partial pressure of U dc The partial pressure of the phase/2, c is-U dc /2. The current flow in the fault state is shown in fig. 4 (a) and 4 (b) for a specific load. At this time, u 1 、u 2 、u 6 、u 0 and u7 Is not affected; u (u) 3 (010) Becomes as follows
As shown in fig. 4 (c); u (u) 5 (001) Become->
As shown in fig. 4 (d); u (u) 4 (011) Becomes a zero vector. In this fault state, the fault can be defined by u only 1 、u 2 、u 6 、u 3S2 and u5S2 The target vectors are synthesized as shown in fig. 4 (e).
(2) Double-pipe open circuit fault at different same side
By S 1 S 3 For example, in the case of an open fault, the current flow in the fault state is shown in fig. 5 (a) and 5 (b) for a specific load. At this time, u 5 、u 0 and u7 Is not affected; u (u) 4 (011) Becomes as follows
As shown in fig. 5 (c); u (u) 6 (101) Becomes as follows
As shown in fig. 5 (d); u (u) 1 (100)、u 2 (110)、u 3 (010) Becomes a zero vector. In this fault state, the fault can be defined by u only 5 、u 4S13 and u6S13 The target vectors are synthesized as shown in fig. 5 (e).
(3) Dissimilar side double-tube open circuit fault
By S 1 S 4 For example, in the case of an open fault, the current flow in the fault state is shown in fig. 6 (a) and 6 (b) for a specific load. At this time, u 3 、u 4 、u 0 and u7 Is not affected; u (u) 2 (110) Becomes as follows
As shown in fig. 6 (c); u (u) 5 (001) Becomes as follows
As shown in fig. 6 (d); u (u) 1 (100)、u 6 (101) Becomes a zero vector. In this fault state, the fault can be defined by u only 3 、u 4 、u 2S14 and u5S14 Synthesizing target vectors, e.g.Fig. 6 (e) shows the structure.
(4) In-phase double-tube open circuit fault
By S 1 S 2 For example, in the case of an open fault, the current flows in the fault state are shown in fig. 7 (a), 7 (b), 7 (c), and 7 (d) for a specific load. At this time, u 0 and u7 Is not affected; u (u) 2 (110) Becomes as follows
As shown in fig. 7 (e); u (u) 3 (010) Becomes as follows
As shown in fig. 7 (f); u (u) 5 (001) Become->
As shown in fig. 7 (g); u (u) 6 (101) Becomes as follows
As shown in fig. 7 (h). In this fault state, the fault can be defined by u only 2S12 、u 3S12 、u 5S12 and u6S12 The target vectors are synthesized as shown in fig. 7 (e).
From the above analysis, it is found that, when an open circuit fault occurs, the phase angle range θ of the target vector is shown in table 3, and the phase angle range of the current vector is shown at the same time
And is the same as θ.
TABLE 3 Voltage vector phase Angle Range under failure
As can be seen from table 3, there is an overlap in the current vector phase angle ranges for the different open faults. It is therefore not feasible to use this as a fault diagnosis criterion only in the phase angle range.
When referring to voltage vector u ref In the observable area, taking the I sector as an example, as shown in FIG. 8 (a), in which the effective electricity isPressure vector u 1 、u 2 Sum zero vector time of action T 1 、T 2 and T0 The method comprises the following steps of:
wherein M is modulation degree, U dc Representing a DC bus voltage; t (T) s Is a carrier period; θ is the phase angle range of the target vector.
When referring to the vector u ref When the current is in the non-observable areas such as sector boundary, low modulation area and the like, two new satisfying T are provided in the carrier period by adopting the complementary non-zero vector to replace the original zero vector min The non-observable region effects are eliminated. As shown in FIG. 8 (b), by combining the zero voltage vector u 0 、u 7 Instead of being complementary non-zero vectors u 3 、u 6 The action time is that,
in the original SVPWM period of time,
in the complementary non-zero vector compensation, the composite voltage vector of the I sector is set as u' ref ：
u' ref T s ＝u 1 T 1 +u 2 T 2 +u 3 T 3 +u 6 T 6 (6)
Also, because of the fact that the liquid,
synthetic vector u' ref The method meets the following conditions:
u' ref T s ＝u 1 T 1 +u 2 T 2 ＝u ref T s (8)
visible u' ref The size and the direction of the (B) are not changed, and the (B) accords with the principle of volt-second balance.
As shown in fig. 9, the effective voltage vector u 1 (100) The action time satisfies the minimum sampling time T min Located in the observable area, can generate sampling points T sam1 ；u 2 (110) Does not satisfy the minimum sampling time T min Located in an unobservable region; at this time, the zero voltage vector u is calculated according to the complementary non-zero vector compensation principle 0 、u 7 Replacement by complementary non-zero vector u 3 、u 6 The action time is T 0 2, and in u 6 Current sampling is carried out during the action, and the sampling point is T sam2 ；T sam1 and Tsam2 Obtaining phase A and phase C currents i respectively are 、-i bre Thereby realizing three-phase current reconstruction.
Reconstructing three-phase current i are 、i bre 、i cre Two-phase components in the alpha beta coordinate system can be obtained through Park transformation:
wherein ,iα Representing the alpha-axis current component, i, after Park conversion β Representing the beta-axis current component after Park conversion; i represents i α and iβ The resultant current vector in the two-phase coordinate system.
i α 、i β Average current vector over 1 cycle
The average current vector synthesis formula is:
wherein ,v＝α,β ，i v (N) represents a current vector, N represents a summation start value, N represents a summation end value, N * Is the number of current samples in a1 cycle,
is the alpha-axis average current component; />
Is the beta-axis average current component; />
Is the average current vector after synthesis.
The phase angle of the current vector can be obtained by an inverse trigonometric function
Average current vector modulus>
And average current vector phase angle
The method comprises the following steps of: />
When the three-phase voltage source type inverter works normally in steady state, i is converted by Park α and iβ The resultant current vector i in the two-phase coordinate system rotates in a circular trajectory, i.e
Two-phase current i α and iβ Average current vector in any period +.>
Is 0; when an open circuit fault occurs in a single or two power switching tubes, the motion trail of a current vector i is changed and the average current vector +.>
Is +.>
Phase angle->
Not constantly 0.
The diagnostic criteria intervals shown in table 4 are obtained by calculating the average value of the current vector in each fault state. Analysis found that the average current vector
Is +.>
Can be used as diagnostic criterion for distinguishing fault types and phase angle +.>
The interval in which the fault location is located is subdivided.
TABLE 4 average current vector diagnostic criteria interval
A specific fault diagnosis flow is shown in fig. 10. First, the phase angle of the current vector i is calculated
By comparison->
And->
Judging the motion trail; second, calculate the average current vector +.>
Is +.>
Phase angle>
By comparison->
And->
And (3) with
Locating a fault position; finally, outputting fault location variable S dio And obtaining a diagnosis result. Wherein (1)>
For the current vector phase angle threshold, k=1, 2, < ->
For the average current vector modulus threshold, k' =1, 2,3, ++>
Is the average current vector phase angle threshold, p is the fault location, S dio For locating the variable for the fault, S dio The tens and units of the number of (2) correspond to the fault positions respectively.
Experiment and result analysis
The experimental platform is shown in fig. 11. In the experiment, the PWM carrier frequency was set to 10kHz. When three-phase current is reconstructed, the sampling signal is sampled twice per period, and the sampling frequency is 20kHz. The experiment uses a three-phase induction motor MODV K48T17D200K, and the parameters are shown in Table 5. Experimental data were collected by an a150 current probe and MDA805A electrically driven analyzer.
Table 5 three-phase induction motor parameters
As shown in fig. 12 (a) - (f), the PWM signal and the sampling pulse of each sector can be seen that the position of the sampling point dynamically changes with the current observation window under different voltage vectors of the sector boundary, and the sampling window satisfies T min Requirements.
In order to verify the phase current reconstruction effect after failure, S is respectively set in the experiment 2 、S 1 S 3 、S 1 S 2 Open circuit failure. The experimental results are shown in fig. 14, 15, and 16. Therefore, the reconstructed three-phase current after the fault can still accurately track the actual current change.
In order to more intuitively represent the phase angle range of the current vector, as shown in fig. 16 (a), park transformation is performed on the three-phase current reconstructed after the fault to obtain the current vector under a two-phase coordinate system, wherein the subscript of the current vector i is the fault position, and the current vector can be found to rotate in the corresponding phase angle range.
FIG. 17 shows vector phase angles for each fault obtained by inverse trigonometric functions
When the current vector is located at the boundary of the coordinate axis, it will cause the inverse trigonometric function operation to be wrong, i.e. +.>
Can only be used as a diagnostic criterion of the current vector motion trail.
The average current vector diagram obtained by averaging the current vectors in fig. 16 (a) with a period of 0.067s is shown in fig. 16 (b). Average current vector modulus
Phase angle->
As shown in fig. 18 and 19, both can respond to and distinguish fault types, and can serve as diagnostic criteria.
Setting occurrence time t of various faults in experiment on =0.067 s, and the fault diagnosis result is shown in fig. 20. It can be seen that the system responded to the fault at t=0.0675 s and correctly distinguished the fault type, with a diagnostic time of 0.5ms.
Aiming at the feasibility and diagnosis time problems of open-circuit fault diagnosis of an inverter under a single sensor of a three-phase voltage source type inverter, the embodiment provides an inverter fault diagnosis strategy based on complementary non-zero vector compensation and average current vector single sensor phase current reconstruction. Through experimental verification, the effectiveness of the proposed strategy is shown in: (1) By adopting two complementary effective non-zero vectors to replace zero vectors, the current sampling time at the position of the direct current bus is ensured to be longer than T min Reliable reconstruction of fault phase current in the current invisible area is realized. (2) By adopting the inverter fault diagnosis method with the current vector phase angle, the average current vector module value and the phase angle as diagnosis criteria, the diagnosis time is 0.5ms, and the rapid positioning of the fault power tube is realized.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, alternatives, and improvements that fall within the spirit and scope of the invention.
Claims (6)
1. A fault diagnosis method for a single-sensor phase current reconstruction three-phase voltage source type inverter is characterized by comprising the following steps:
step one: analyzing the existence mechanism of a current unobservable area of a direct-current bus single sensor and a voltage vector synthesis mechanism under four types of faults, namely single-tube open circuit, heterogeneous same-side double-tube open circuit, heterogeneous different-side double-tube open circuit and in-phase double-tube open circuit;
step two: by adopting complementary non-zero vectors to replace the original zero vectors, two new sampling windows meeting the minimum sampling time are provided in the carrier period, the influence of an unobservable area is eliminated, and three-phase current reconstruction is realized;
step three: and calculating a current vector phase angle, an average current vector module value and an average current vector phase angle according to the reconstructed three-phase current, and performing fault location by taking the current vector phase angle, the average current vector module value and the average current vector phase angle as diagnosis criteria to obtain a diagnosis result.
2. The single-sensor-phase-current-reconstruction three-phase-voltage-source-type inverter fault diagnosis method according to claim 1, wherein the existence mechanism of the direct-current bus single-sensor-current unobservable region is: in the SVPWM modulation mode, the switching state of each phase bridge arm switching device can be controlled by a variable S p (p.epsilon. { a, b, c }) represents S when the upper arm is on p =1, S for conducting the lower arm p =0; space voltage vector u i (S a ，S b ，S c ) I e {0,1,2,3,4,5,6,7} represents 8 different switch states, including 6 effective voltage vectors and 2 zero voltage vectors; the whole working area can be divided into 6 sectors, and each sector comprises a normal area, a sector boundary and a low modulation area, wherein the normal area belongs to an observable area, and the sector boundary and the low modulation area belong to an unobservable area.
3. The fault diagnosis method for the single-sensor phase current reconstruction three-phase voltage source type inverter according to claim 2, wherein in the second step, the specific implementation method is as follows:
when referring to voltage vector u ref In the observable region, taking an example of an I sector, where the effective voltage vector u 1 、u 2 Sum zero vector time of action T 1 、T 2 and T0 The method comprises the following steps of:
wherein ,
u is a modulation degree dc Representing a DC bus voltage; t (T) s Is a carrier period; θ is the phase angle range of the target vector;
when referring to voltage vector u ref When in the unobservable region, the zero voltage vector u is calculated 0 、u 7 Instead of being complementary non-zero vectors u 3 、u 6 The action time is as follows:
in the complementary non-zero vector compensation, the synthesized voltage vector of the I sector is set as u' ref ：
u′ ref T s ＝u 1 T 1 +u 2 T 2 +u 3 T 3 +u 6 T 6 ；
Due to
Synthetic vector u' ref The method meets the following conditions: u's' ref T s ＝u 1 T 1 +u 2 T 2 ＝u ref T s ；
Effective voltage vector u 1 (100) The action time satisfies the minimum sampling time T min Located in the observable area, can generate sampling points T sam1 ；u 2 (110) Does not satisfy the minimum sampling time T min Located in an unobservable region; at this time, the zero voltage vector u is calculated according to the complementary non-zero vector compensation principle 0 、u 7 Replacement by complementary non-zero vector u 3 、u 6 The action time is T 0 2, and in u 6 Current sampling is carried out during the action, and the sampling point is T sam2 ；T sam1 and Tsam2 Obtaining phase A and phase C currents i respectively are 、-i bre Thereby realizing three-phase powerStream reconstruction.
4. The method for fault diagnosis of a single-sensor phase current reconstruction three-phase voltage source type inverter according to claim 3, wherein the minimum sampling time T min The expression of (2) is:
T min ＝T on +T db +T rise +T sr +T con ；
wherein ,Ton For switching device on time, T db For PWM dead time, T con For AD conversion time, T rise To sample the rise time of the circuit current, T sr Is the slew rate of the operational amplifier voltage.
5. The method for diagnosing faults of the single-sensor phase current reconstruction three-phase voltage source type inverter according to claim 1, wherein the method for calculating a current vector phase angle, an average current vector module value and an average current vector phase angle according to the reconstructed three-phase current is as follows:
reconstructing three-phase current i are 、i bre 、i cre Two-phase components in the alpha beta coordinate system can be obtained through Park transformation:
wherein ,iα Representing the alpha-axis current component, i, after Park conversion β Representing the beta-axis current component after Park conversion;
i represents i α and iβ A composite current vector in a two-phase coordinate system;
i α 、i β average current vector over 1 cycle
The average current vector synthesis formula is:
wherein v=α, β, i v (N) represents a current vector, N represents a summation start value, N represents a summation end value, N * Is the number of current samples in a1 cycle,
is the alpha-axis average current component; />
Is the beta-axis average current component; />
Is the average current vector after synthesis;
the phase angle of the current vector can be obtained by an inverse trigonometric function
Average current vector modulus>
And average current vector phase angle>
The method comprises the following steps of:
when the three-phase voltage source type inverter works normally in steady state, i is converted by Park α and iβ The resultant current vector i in the two-phase coordinate system rotates in a circular trajectory, i.e
Two-phase current i α and iβ Average current vector in any periodThe amount mu is 0; when an open circuit fault occurs in a single or two power switching tubes, the motion trail of a current vector i is changed and the average current vector +.>
Is +.>
Phase angle->
Not constantly 0.
6. The fault diagnosis method for the single-sensor phase current reconstruction three-phase voltage source type inverter according to claim 5, wherein the fault localization is performed by using a current vector phase angle, an average current vector module value and an average current vector phase angle as diagnosis criteria, and the method for obtaining a diagnosis result is as follows:
calculating the phase angle of the current vector i
By comparison->
And->
Judging the motion trail;
calculating an average current vector
Is +.>
Phase angle>
By comparison->
And->
And->
Locating a fault position;
output fault location variable S dio Obtaining a diagnosis result;
wherein ,
for the current vector phase angle threshold, k=1, 2, < ->
For the average current vector modulus threshold, k' =1, 2,3,
is the average current vector phase angle threshold, p is the fault location, S dio For locating the variable for the fault, S dio The tens and units of the number of (2) correspond to the fault positions respectively. />
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| CN117650737A (en) * | 2023-11-28 | 2024-03-05 | 江南大学 | Novel SVPWM-based PMSM single-current sensor control method |
| CN118244180A (en) * | 2024-03-07 | 2024-06-25 | 青岛水下机器人系统有限公司 | Multi-current sensor fault diagnosis method for motor |
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| CN114114062A (en) * | 2021-11-05 | 2022-03-01 | 郑州轻工业大学 | Fault detection device and method for direct-current bus single-current sensor inverter |
| CN117650737A (en) * | 2023-11-28 | 2024-03-05 | 江南大学 | Novel SVPWM-based PMSM single-current sensor control method |
| CN118244180A (en) * | 2024-03-07 | 2024-06-25 | 青岛水下机器人系统有限公司 | Multi-current sensor fault diagnosis method for motor |
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