Virtual flux linkage construction prediction control system for one-phase-lacking fault of permanent magnet synchronous motor

Abstract

The invention relates to the technical field of multi-phase motor control, and particularly discloses a permanent magnet synchronous motor one-phase-lacking fault virtual flux linkage construction prediction control system, which comprises a model analysis module used for analyzing a mathematical model of a permanent magnet synchronous motor when a one-phase-lacking fault occurs according to a mathematical model of the permanent magnet synchronous motor without a fault; the evaluation function construction module is used for constructing an evaluation function related to a torque flux linkage and a zero sequence on the basis of a mathematical model of the permanent magnet synchronous motor when the permanent magnet synchronous motor lacks a phase fault and a motor equation virtual flux linkage construction scheme based on a virtual variable; the optimal control module is used for obtaining an optimal voltage vector based on an evaluation function related to a torque flux linkage and a zero sequence, and obtaining an optimal control result of the permanent magnet synchronous motor based on the optimal voltage vector; the method is used for unifying various one-phase-lacking faults of the permanent magnet synchronous motor, controlling a system through a calculated optimal voltage vector, and continuously adjusting a zero-sequence weight coefficient so as to obtain an optimal control effect.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-phase motor control, and in particular to a virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase failure. Background Art

[0002] At present, permanent magnet synchronous motors have high torque density and power density, as well as strong fault tolerance and reliability, and are the subject of extensive research attention by scholars. However, traditional permanent magnet synchronous motors use deep and narrow slots, which results in a small proportion of effective magnetic flux in the motor stator teeth and limited torque density. At the same time, existing control strategies also fail to fully consider the large inductance and operating characteristics of the motor. In response to the above problems, starting from the control strategy, a predictive control strategy for constructing virtual flux linkage for permanent magnet synchronous motors with one-phase missing fault is proposed.

[0003] However, the traditional direct torque control is a strong and effective driving solution for permanent magnet synchronous motors due to its fast torque flux control capability. When combined with the large inductance characteristics of permanent magnet synchronous motors, it can simultaneously obtain the dual advantages of good dynamic performance and excellent current performance. However, the disadvantage is that the selection of the offline optimal switch table does not consider the influence of speed and load. At the same time, the dual three-phase permanent magnet synchronous motor has many switch vectors, and it is difficult to construct the optimal switch vector table. The situation is even more complicated when considering zero-sequence current suppression.

[0004] Therefore, the present invention proposes a virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase failure. Summary of the invention

[0005] The present invention provides a prediction control system for constructing a virtual flux linkage of a permanent magnet synchronous motor with a missing phase fault, which is used to add prediction control to direct torque control, and simultaneously analyzes a mathematical model when a missing phase fault occurs, derives torque, flux linkage and zero-sequence mathematical models applicable to various missing phase faults, and proposes a missing phase fault-tolerant control strategy based on a new virtual variable, so that various missing phase faults can be unified, and finally a voltage vector that minimizes an evaluation function is selected as an optimal voltage vector to be substituted into the calculation of the optimal voltage vector, through which the system can be controlled, and the zero-sequence weight coefficient is continuously adjusted to obtain the best control effect.

[0006] The present invention provides a virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault, comprising:

[0007] A model analysis module is used to analyze the mathematical model of the permanent magnet synchronous motor when it is in a state of one-phase failure based on the mathematical model of the permanent magnet synchronous motor when it is fault-free;

[0008] An evaluation function construction module is used to construct an evaluation function related to torque flux and zero sequence based on a mathematical model of a permanent magnet synchronous motor in the event of a one-phase failure and a virtual flux construction scheme of a motor equation based on virtual variables;

[0009] The optimal control module is used to obtain an optimal voltage vector based on an evaluation function related to torque flux and zero sequence, and to obtain an optimal control result of the permanent magnet synchronous motor based on the optimal voltage vector.

[0010] Preferably, the model analysis module analyzes the mathematical model of the permanent magnet synchronous motor when one phase is missing according to the mathematical model of the permanent magnet synchronous motor without fault, and the method comprises:

[0011] The first two rows of the transformation matrix from the natural coordinate system to the two-phase stationary coordinate system of the permanent magnet synchronous motor when there is no fault [T α ] and [T β ] is expressed as:

[0012]

[0013] Among them, K α and K β is the coefficient of the permanent magnet synchronous motor without fault, γ j (j=1, 2, 3, 4, 5, 6) is the torque angle of the permanent magnet synchronous motor when there is no fault;

[0014] The first two rows of the transformation matrix [T α ] and [T β ], determine the motor torque expression of the permanent magnet synchronous motor when one phase is missing.

[0015] Preferably, the coefficient of the permanent magnet synchronous motor without fault is:

[0016]

[0017] Preferably, the torque angle γ of the permanent magnet synchronous motor when there is no fault j (j=1, 2, 3, 4, 5, 6) is:

[0018]

[0019] Preferably, the first two rows of the transformation matrix [T α ] and [T β ], determine the motor torque expression of the permanent magnet synchronous motor when one phase is missing, including:

[0020] The first two rows of the transformation matrix from the natural coordinate system to the two-phase stationary coordinate system of the permanent magnet synchronous motor when one phase is missing are [Tα′ ] and [T β′ ] is expressed as:

[0021]

[0022] Among them, K α and K β′ is the coefficient of the permanent magnet synchronous motor when one phase is missing;

[0023] The first two rows of the transformation matrix [T α′ ] and [T β′ ], and obtain the motor torque T of the permanent magnet synchronous motor when one phase is missing e The expression is:

[0024]

[0025] Among them, n p is the pole pair number, ψ′ sα is the α-axis flux component of the permanent magnet synchronous motor when one phase is missing, ψ′ sβ is the β-axis flux component of the permanent magnet synchronous motor when one phase is missing, i′ sα is the α-axis current component of the permanent magnet synchronous motor when one phase is missing, i′ sβ is the β-axis current component of the permanent magnet synchronous motor when one phase is missing, L sσ is the phase winding leakage inductance.

[0026] Preferably, the coefficient of the permanent magnet synchronous motor when one phase is missing is:

[0027]

[0028] Preferably, the evaluation function construction module is based on the mathematical model of the permanent magnet synchronous motor when one phase is missing and the motor equation virtual flux construction scheme based on virtual variables, and the method for constructing the evaluation function related to the torque flux and zero sequence includes:

[0029] According to the current relationship before and after the permanent magnet synchronous motor is missing, the α-axis virtual current i is established. xsα and the β-axis virtual current i xsβ ;

[0030] Construct the virtual magnetic flux ψ of the α axis xsα and the β-axis virtual flux ψ xsβ ;

[0031] α-axis virtual current i xsα and the β-axis virtual current i xsβ and the α-axis virtual flux ψ xsα and the β-axis virtual flux ψ xsβ , the new torque formula is as follows:

[0032] T e =n p [ψ sα -ψ sβ i sα ];

[0033] Among them, ψ sα is the α-axis magnetic flux component, ψ sβ is the β-axis magnetic flux component, i sα is the α-axis current component;

[0034] Based on the new torque formula, the evaluation function of torque flux and zero sequence is constructed.

[0035] Preferably, according to the current relationship before and after the permanent magnet synchronous motor is out of phase, the α-axis virtual current i is established. xsα and the β-axis virtual current i xsβ ,include:

[0036]

[0037] Preferably, construct the α-axis virtual magnetic flux ψ xsα and the β-axis virtual flux ψ xsβ ,include:

[0038]

[0039] Among them, L sm =(L dm +L qm ) / 2,L rs =(L dm -L qm ) / 2,L dm is the main flux d-axis inductance, L qm is the main flux q-axis inductance, θ r is the rotor position angle; ψ f is the magnetic flux.

[0040] Preferably, the optimal control module obtains the optimal voltage vector based on the evaluation function of the torque flux and the zero sequence, and the method for obtaining the optimal control result of the permanent magnet synchronous motor based on the optimal voltage vector includes:

[0041] Substitute the voltage vector into the evaluation function related to torque flux and zero sequence to calculate the evaluation function value corresponding to each vector, and take the voltage vector corresponding to the minimum value of the evaluation function as the optimal voltage control vector;

[0042] The permanent magnet synchronous motor is controlled based on the optimal voltage control vector to obtain the best control result of the permanent magnet synchronous motor.

[0043] Compared with the prior art, the beneficial effects of the present invention are as follows: predictive control is added to direct torque control, and a mathematical model of a one-phase failure is analyzed at the same time, torque, flux linkage and zero-sequence mathematical models applicable to various one-phase failures are derived, and a phase failure fault-tolerant control strategy based on a new virtual variable is proposed, so that various one-phase failures can be unified, and finally a voltage vector that minimizes an evaluation function is selected as the optimal voltage vector to be substituted into the calculation of the optimal voltage vector, through which the system can be controlled, and the zero-sequence weight coefficient is continuously adjusted to obtain the best control effect.

[0044] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in this application document.

[0045] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0047] Figure 1 A schematic diagram of the functional modules included in the virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase failure in an embodiment of the present invention;

[0048] Figure 2 A process intention of constructing a predictive control method for a virtual flux linkage of a permanent magnet synchronous motor with a one-phase failure in an embodiment of the present invention;

[0049] Figure 3 A block diagram of the research principle of predictive control for virtual flux linkage construction of a permanent magnet synchronous motor with one-phase missing fault in an embodiment of the present invention. DETAILED DESCRIPTION

[0050] The preferred embodiments of the present invention are described below in conjunction with the accompanying drawings. It should be understood that the preferred embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0051] Embodiment 1:

[0052] The present invention provides a virtual flux linkage prediction control system for a permanent magnet synchronous motor with one phase missing. Figure 1 ,include:

[0053] A model analysis module is used to analyze the mathematical model of the permanent magnet synchronous motor when it is in a state of one-phase failure based on the mathematical model of the permanent magnet synchronous motor when it is fault-free;

[0054] An evaluation function construction module is used to construct an evaluation function related to torque flux and zero sequence based on a mathematical model of a permanent magnet synchronous motor in the event of a one-phase failure and a virtual flux construction scheme of a motor equation based on virtual variables;

[0055] The optimal control module is used to obtain an optimal voltage vector based on an evaluation function related to torque flux and zero sequence, and to obtain an optimal control result of the permanent magnet synchronous motor based on the optimal voltage vector.

[0056] A predictive control method for constructing virtual flux linkage of a permanent magnet synchronous motor with one-phase failure, such as Figure 2 As shown, it includes the following steps:

[0057] Step 1, construct a mathematical model of a permanent magnet synchronous motor with a one-phase failure;

[0058] During normal operation, the first two lines of the natural coordinate system to the two-phase stationary coordinate system are expressed as follows:

[0059]

[0060] in:

[0061]

[0062] The first two lines after missing a phase change as follows:

[0063]

[0064] in:

[0065]

[0066] The known αβ axis magnetic flux formula is as follows:

[0067]

[0068] Substituting formula (5) into formula (7), we can derive:

[0069]

[0070] Among them, ψ′ sα and ψ′ sβ is the αβ axis flux after a phase failure, i′ sα and i′ sβ is the current after one phase is missing, ψ′ rα and ψ′ rβ is the flux component of the rotor flux coupled to the αβ axis, and at the same time:

[0071]

[0072] From formula (9), it can be seen that the main diagonal and the secondary diagonal are not equal. From formula (10), it can be seen that the components of the magnetic flux coupled to the αβ axis are also not equal, and the magnetic flux trajectory is an ellipse.

[0073] The voltage equation is:

[0074]

[0075] By taking the derivative of the magnetic energy with respect to the motor rotor angle, the torque equation is as follows:

[0076]

[0077] Substituting formulas (8) to (10) into formula (12), we obtain:

[0078]

[0079] Formula (13) has two more phases than the normal torque formula, so the flux and torque need to be reconstructed. Here, the motor equation based on virtual variables is used.

[0080] Step 2: Reconstruct the motor equation based on new virtual variables;

[0081] According to the current relationship before and after phase loss, the virtual current is established as follows:

[0082]

[0083] Using virtual current to represent actual current, the formula is as follows:

[0084]

[0085] The virtual magnetic link is constructed as follows:

[0086]

[0087] Using virtual magnetic flux to represent actual magnetic flux, the formula is as follows:

[0088]

[0089] Substituting formulas (8) to (10) into formula (16), we can obtain:

[0090]

[0091] Substituting (14) into (18), we obtain:

[0092]

[0093] Substituting formulas (15) and (17) into formula (13), another torque expression can be obtained as follows:

[0094]

[0095]

[0096] It can be seen from formula (19) that the diagonal coefficients of the flux equation are equal, indicating that the flux trajectory is a circle. If the virtual stator flux trajectory is controlled to be a circle, the motor torque pulsation will be reduced; the virtual stator current determines the virtual stator flux, so the virtual stator current must be controlled to be a circle. The stator current when one phase is missing can be obtained by formula (14) and formula (5), but formula (5) needs to be changed according to different phase missing conditions, so the one-phase missing condition must be handled uniformly. First, calculate i′ by formula (5) sα and i′ sβ When the current component corresponding to the fault and the corresponding transformation component in formula (5) are no longer removed, the fault phase current is regarded as a "sub-healthy" state where the current is always zero, and then directly transformed by formula (5); secondly, formula (5) is no longer used as the transformation matrix, but i′ is obtained according to the relationship between formula (1) and formula (5): sα and i′ sβ From the above, we can see that the αβ axis current component obtained by the normal coordinate matrix formula (1) is i sα and i sβ , and the αβ axis current component obtained in the first step by equation (5) and considering the fault phase current as zero is i′ sα and i′ sβ , the relationship between the two is as follows:

[0097]

[0098] Simplifying, we get:

[0099]

[0100] From formula (14) and formula (22), we can get:

[0101]

[0102] Substituting formula (23) into formula (19), we get:

[0103]

[0104]

[0105] Therefore, the torque formula of formula (20) can be expressed as:

[0106] T e =n p [ψ sα -ψ sβi sα ] (25)

[0107] Therefore, the motor equation reconstruction of the proposed virtual variables is completed, various phase-lack faults are unified, and the control is simplified.

[0108] Construct the evaluation function of torque flux and zero sequence, substitute the voltage vector to calculate the evaluation function value corresponding to each vector, the voltage vector corresponding to the minimum value of the evaluation function is the optimal voltage vector, through which the system can be controlled, and the zero sequence weight coefficient is continuously adjusted to obtain the best control effect. The control principle block diagram is shown in the figure. Figure 3 shown.

[0109] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase failure, characterized in that: include: A model analysis module is used to analyze the mathematical model of the permanent magnet synchronous motor when it is in a state of one-phase failure based on the mathematical model of the permanent magnet synchronous motor when it is fault-free; An evaluation function construction module is used to construct an evaluation function related to torque flux and zero sequence based on a mathematical model of a permanent magnet synchronous motor in the event of a one-phase failure and a virtual flux construction scheme of a motor equation based on virtual variables; The optimal control module is used to obtain an optimal voltage vector based on an evaluation function related to torque flux and zero sequence, and to obtain an optimal control result of the permanent magnet synchronous motor based on the optimal voltage vector.

2. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 1 is characterized in that: The model analysis module analyzes the mathematical model of the permanent magnet synchronous motor when one phase is missing according to the mathematical model of the permanent magnet synchronous motor without fault, including: The first two rows of the transformation matrix from the natural coordinate system to the two-phase stationary coordinate system of the permanent magnet synchronous motor when there is no fault [T α ] and [T β ] is expressed as: Among them, K α and K β is the coefficient of the permanent magnet synchronous motor without fault, γ j (j=1, 2, 3, 4, 5, 6) is the torque angle of the permanent magnet synchronous motor when there is no fault; The first two rows of the transformation matrix [T α ] and [T β ], determine the motor torque expression of the permanent magnet synchronous motor when one phase is missing.

3. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 2 is characterized in that: The coefficient of permanent magnet synchronous motor without fault is:

4. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 2 is characterized in that: Torque angle γ of permanent magnet synchronous motor when there is no fault j (j=1, 2, 3, 4, 5, 6) is:

5. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 4 is characterized in that: The first two rows of the transformation matrix [T α ] and [T β ], determine the motor torque expression of the permanent magnet synchronous motor when one phase is missing, including: The first two rows of the transformation matrix from the natural coordinate system to the two-phase stationary coordinate system of the permanent magnet synchronous motor when one phase is missing are [T α′ ] and [T β ] is expressed as: Among them, K α and K β′ is the coefficient of the permanent magnet synchronous motor when one phase is missing; The first two rows of the transformation matrix [T α′ ] and [T β′ ], and obtain the motor torque T of the permanent magnet synchronous motor when one phase is missing e The expression is: Among them, n p is the pole pair number, ψ′ sα is the α-axis flux component of the permanent magnet synchronous motor when one phase is missing, ψ′ sβ is the β-axis flux component of the permanent magnet synchronous motor when one phase is missing, i′ sα is the α-axis current component of the permanent magnet synchronous motor when one phase is missing, i′ sβ is the β-axis current component of the permanent magnet synchronous motor when one phase is missing, L sσ is the phase winding leakage inductance.

6. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 5 is characterized in that: The coefficient of permanent magnet synchronous motor when one phase is missing is:

7. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 6 is characterized in that: The evaluation function construction module is based on the mathematical model of the permanent magnet synchronous motor when one phase is missing and the virtual flux construction scheme of the motor equation based on virtual variables, and constructs a method for evaluating the torque flux and zero sequence, including: According to the current relationship before and after the permanent magnet synchronous motor is missing, the α-axis virtual current i is established. xsα and the β-axis virtual current i xsβ ; Construct the virtual magnetic flux ψ of the α axis xsα and the β-axis virtual flux ψ xsβ ; α-axis virtual current i xsα and the β-axis virtual current i xsβ and the α-axis virtual flux ψ xsα and the β-axis virtual flux ψ xsβ , the new torque formula is as follows: T e =n p [ψ sα -ψ sβ I sα ]; Among them, ψ sα is the α-axis magnetic flux component, ψ sβ is the β-axis magnetic flux component, i sα is the α-axis current component; Based on the new torque formula, the evaluation function of torque flux and zero sequence is constructed.

8. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 7 is characterized in that: According to the current relationship before and after the permanent magnet synchronous motor is missing, the α-axis virtual current i is established. xsα and the β-axis virtual current i xsβ , include:

9. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 7 is characterized in that: Construct the virtual magnetic flux ψ of the α axis xsα and the β-axis virtual flux ψ xsβ , include: Among them, L sm =(L dm +L qm ) / 2,L rs =(L dm -L qm ) / 2,L dm is the main flux d-axis inductance, L qm is the main flux q-axis inductance, θ r is the rotor position angle; ψ f is the magnetic flux.

10. The virtual flux linkage prediction control system for a permanent magnet synchronous motor with one-phase missing fault according to claim 1, characterized in that: The optimal control module obtains an optimal voltage vector based on an evaluation function related to torque flux and zero sequence. The method for obtaining an optimal control result of the permanent magnet synchronous motor based on the optimal voltage vector includes: Substitute the voltage vector into the evaluation function related to torque flux and zero sequence to calculate the evaluation function value corresponding to each vector, and use the voltage vector corresponding to the minimum value of the evaluation function as the optimal voltage control vector; control the permanent magnet synchronous motor based on the optimal voltage control vector to obtain the best control result of the permanent magnet synchronous motor.

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