A dynamic virtual voltage vector synthesis method in model predictive control of multiphase permanent magnet motor

Abstract

The application belongs to the technical field of electric machines, and discloses a dynamic virtual voltage vector synthesis method in model prediction control of a multiphase permanent magnet motor, comprising the following steps: judging a sector where a reference voltage vector is located according to an angle of the reference voltage vector, and obtaining two basic virtual voltage vectors; determining the action proportion of the two basic virtual voltage vectors and the action time of a zero vector according to the relative angle of the reference voltage vector in the sector; and obtaining a dynamic virtual voltage vector according to the two basic virtual voltage vectors and the zero vector. The method of the application embodiment can simply and quickly obtain each basic voltage vector and the action time thereof for synthesizing the dynamic virtual voltage vector, avoids the process of increasing the calculation burden such as iterative optimization and introducing a weight factor; and the obtained dynamic virtual voltage vector can realize arbitrary adjustment of the amplitude and the angle, realizes complete coincidence with the reference voltage vector, and eliminates the control error.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of motor control, and particularly relates to a dynamic virtual voltage vector synthesis method in model predictive control of a multiphase permanent magnet motor. BACKGROUND

[0002] The multiphase permanent magnet motor has replaced the traditional three-phase permanent magnet motor in many applications due to its high reliability, small power per phase, small torque ripple and other advantages. At the same time, the limited control set model predictive control has attracted great attention in the multiphase motor drive system. Compared with the traditional control strategy, the model predictive control has a fast dynamic response and is easy to include nonlinear constraints. In particular, for the multivariable control in the multiphase driver, the model predictive control has a simple structure and does not need to add a new controller.

[0003] The virtual voltage vector method has the advantages of eliminating harmonic current, simplifying the number of control sets and reducing the calculation burden, and is a commonly used technology in the model predictive control of the multiphase motor.

[0004] The existing virtual voltage vector method is to obtain a plurality of virtual voltage vectors without harmonic components through offline calculation, and then store them in the processor for direct calling during program running. In order to improve the steady-state performance, the amplitude of the virtual voltage vector is changed by optimizing the duty ratio to realize the radial adjustment of the vector point in the fundamental plane.

[0005] The existing technology has the following disadvantages: the virtual voltage vector is a discrete point obtained through offline calculation, and can only be adjusted in the radial direction (amplitude) through the optimization of the duty ratio, and cannot be adjusted in the tangential direction (arbitrary angle), so it is difficult to completely eliminate the control error.

[0006] Therefore, how to realize the arbitrary angle adjustment of the virtual voltage vector is a problem to be solved at present. SUMMARY

[0007] The embodiment of the present application provides a dynamic virtual voltage vector synthesis method in model predictive control of a multiphase permanent magnet motor, so as to solve the problem that the virtual voltage vector cannot be adjusted in an arbitrary angle in the prior art. In order to have a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. The summary is not a general review, nor is it intended to determine key / important constituent elements or delineate the scope of protection of these embodiments. The only purpose is to present some concepts in a simple form as a prelude to the detailed description below.

[0008] According to a first aspect of the embodiment of the present application, a dynamic virtual voltage vector synthesis method in model predictive control of a multiphase permanent magnet motor is provided.

[0009] In one embodiment, the dynamic virtual voltage vector synthesis method in the model predictive control of the multiphase permanent magnet motor comprises the following steps:

[0010] According to the angle of the reference voltage vector, determine the sector where the reference voltage vector is located, and obtain two basic virtual voltage vectors;

[0011] According to the relative angle of the reference voltage vector in the sector, determine the action proportion of the two basic virtual voltage vectors, and the action time of the zero vector;

[0012] According to the two basic virtual voltage vectors and a zero vector, obtain a dynamic virtual voltage vector.

[0013] Optionally, in the step of determining the sector where the reference voltage vector is located according to the angle of the reference voltage vector, and obtaining two basic virtual voltage vectors, the two basic virtual voltage vectors are obtained by the following steps:

[0014] Transform the reference voltage vector into the α-β coordinate system:

[0015]

[0016] Where θ is the rotor electrical angle; is the voltage reference value in the fundamental plane d-q coordinate system; is the voltage reference value in the fundamental plane α-β coordinate system;

[0017] The reference voltage vector is expressed as:

[0018] The angle of the reference voltage vector in the α-β plane is:

[0019]

[0020] Determine θ ref The sector where the reference voltage vector is located, and obtain two basic virtual voltage vectors and Where p=m+1, and m is the sector number.

[0021] Optionally, the relative angle θ rela of the reference voltage vector in the sector is obtained by the following method:

[0022] θ rela = θ ref -ε

[0023] Where ε is the starting angle of the sector where the reference voltage vector is located.

[0024] Optionally, the action proportion η of the two basic virtual voltage vectors is obtained by the following method:

[0025]

[0026] wherein σ is the angle occupied by each sector.

[0027] Optionally, the action time of the zero vector is obtained by the following steps:

[0028] First, a temporary voltage vector V temp is obtained according to two basic virtual voltage vectors and action ratios.

[0029] Then, the action time of the zero vector V temp is obtained by calculating the duty ratio of the temporary voltage vector V

[0030] Optionally, the temporary voltage vector V temp is obtained by the following formula:

[0031]

[0032] Optionally, the temporary voltage vector V temp is obtained by the following steps:

[0033]

[0034] wherein T s is a sampling period, the duty ratio δ ranges from 0 to 1, s v and s0 are the i temp current slopes when V q and V0 act, respectively, and the calculation formula is:

[0035]

[0036]

[0037] wherein ψ is the quadrature-axis component of the temporary voltage vector V temp on the fundamental plane, R s is the stator resistance, ψ f is the permanent magnet flux linkage, ω e is the rotor electrical angular velocity, i q and i d are the quadrature-axis and direct-axis current components on the fundamental plane, respectively, and L q is the quadrature-axis inductance component on the fundamental plane. is the reference value of the quadrature-axis current component on the fundamental plane. is the delayed and compensated value of the quadrature-axis current component on the fundamental plane. is the delayed and compensated value of the direct-axis current component on the fundamental plane.

[0038] Optionally, the dynamic virtual voltage vector DV 3 The method is obtained by the following steps:

[0039]

[0040] According to a second aspect of the embodiments of the present application, a computer device is provided.

[0041] In some embodiments, the computer device comprises a memory and a processor, the memory stores a computer program, and the processor implements the steps of the above method when executing the computer program.

[0042] The technical solutions provided by the embodiments of the present application can include the following beneficial effects:

[0043] The various basic voltage vectors and their action times for synthesizing the dynamic virtual voltage vector can be simply and quickly obtained, avoiding the processes of iterative optimization and introducing weight factors to increase the calculation burden;

[0044] The obtained dynamic virtual voltage vector can realize arbitrary adjustment of amplitude and angle, realize complete coincidence with the reference voltage vector, and eliminate control error.

[0045] It should be understood that the above general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0046] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the present application.

[0047] Figure 1 is a flow chart of a dynamic virtual voltage vector synthesis method in a multiphase permanent magnet motor model predictive control according to an exemplary embodiment;

[0048] Figure 2 is a virtual voltage vector diagram of a harmonic-free voltage component obtained offline;

[0049] Figure 3 is a basic virtual voltage vector schematic diagram according to an exemplary embodiment;

[0050] Figure 4 is a control effect diagram of the dynamic virtual voltage vector after the fundamental plane quadrature-axis current component obtained by applying the method of the present application;

[0051] Figure 5 is a control effect diagram of the dynamic virtual voltage vector after the fundamental plane direct-axis current component obtained by applying the method of the present application;

[0052] Figure 6 is a structural diagram of a computer device according to an exemplary embodiment. DETAILED DESCRIPTION

[0053] The following description and drawings are illustrative of the specific embodiments herein and are not intended to be limiting. Parts and features of some embodiments can be included or replaced by parts and features of other embodiments. The scope of the embodiments herein includes the whole area of possibilities of the claims and all available equivalents of the claims. In this document, the terms "first", "second" and the like do not imply any actual relationship or order between elements, but are used to distinguish one element from another. In fact, a first element can also be referred to as a second element and a second element as a first element without departing from the scope of the present disclosure. Also, the terms "comprises", "comprising", or any other variation thereof are intended to cover a non-exclusive inclusion, such that a structure, device or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such structure, device or apparatus. Without further limitation, an element defined by an "including a" does not exclude the presence of additional identical elements in the structure, device or apparatus that includes the element. The various embodiments are described in a progressive manner, each focusing on the differences from other embodiments, and the same or similar parts between embodiments can be mutually referred to.

[0054] In this document, the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, and are used only for the convenience of description herein and simplification of description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present disclosure. In the description herein, unless otherwise specified and limited, the terms "mount", "connect", "connection" should be interpreted broadly, for example, it can be a mechanical connection or an electrical connection, it can be a communication between two elements inside, it can be a direct connection or an indirect connection through an intermediate medium, and the specific meaning of the above terms can be understood by those skilled in the art according to the specific circumstances.

[0055] In this document, the term "multiple" means two or more, unless otherwise specified.

[0056] In this document, the character " / " represents an "or" relationship between the objects before and after it. For example, A / B means A or B.

[0057] In this document, the term "and / or" is a descriptive term involving a conjunctive relationship that also permits a disjunctive relationship. For example, A and / or B allows A to be present alone, B to be present alone, or both A and B to be present.

[0058] In the case of no conflict, the embodiments in the application and the features in the embodiments can be combined with each other.

[0059] Figure 1 An embodiment of a dynamic virtual voltage vector synthesis method in model predictive control of a multiphase permanent magnet motor of the application is shown.

[0060] In this alternative embodiment, the dynamic virtual voltage vector synthesis method in model predictive control of a multiphase permanent magnet motor comprises the following steps:

[0061] Step S1, according to the angle of the reference voltage vector, determine the sector it is in, and obtain two basic virtual voltage vectors;

[0062] Step S2, according to the relative angle of the reference voltage vector in the sector, determine the action proportion of the two basic virtual voltage vectors, and the action time of the zero vector;

[0063] Step S3, according to the two basic virtual voltage vectors and a zero vector, obtain a dynamic virtual voltage vector.

[0064] This application takes a nine-phase permanent magnet motor as an example, and those skilled in the art can extend it to other multiphase permanent magnet motors according to the teaching of the embodiments of the application.

[0065] According to the existing virtual voltage vector technology, the virtual voltage vector of the harmonic-free voltage component obtained offline is as shown in Figure 2 There are 18 fixed discrete vector points V1 3 to V138, defined as basic virtual voltage vectors.

[0066] With these vector points and the zero point as boundaries, the fundamental plane can be evenly divided into 18 sectors, as shown in Table 1, each sector contains three voltage vectors, i.e. two basic virtual voltage vectors and a zero vector.

[0067] Table 1: Angle corresponding to sector division

[0068] Sector Angle (°) Sector Angle (°) 1 10-30 10 190-210 2 30-50 11 210-230 3 50-70 12 230-250 4 70-90 13 250-270 5 90-110 14 270-290 6 110-130 15 290-310 7 130-150 16 310-330 8 150-170 17 330-350 9 170-190 18 350-10

[0069] Using space vector decoupling technology, an n-phase motor can be decomposed into (n-1) / 2 sub-planes (n is odd) or n / 2 sub-planes (n is even), since the virtual voltage vector technology has eliminated all voltage components on the harmonic plane, only the fundamental plane needs to be considered.

[0070] The voltage equation of the permanent magnet motor is as follows:

[0071]

[0072] where R is the stator resistance, ψ is the permanent magnet flux linkage, ω is the rotor electrical angular velocity, i and i are the fundamental plane quadrature and direct current components, L and L are the fundamental plane quadrature and direct inductance components, v and v are the fundamental plane quadrature and direct voltage components. s f e q d q d q d

[0073] According to the forward Euler formula:

[0074]

[0075] where T is the sampling time interval. s

[0076] Substituting the forward Euler formula into the voltage equation, the current prediction model is obtained:

[0077]

[0078] Considering the one-beat delay compensation of the digital processor, the current prediction model is modified to two-beat prediction:

[0079]

[0080] According to the zero-error principle, let:

[0081]

[0082] where and are the reference values of the fundamental plane quadrature and direct current components. Substituting them into the current prediction model, we get:

[0083]

[0084]

[0085] Thus, the reference voltage vector is obtained.

[0086] The significance of the reference voltage vector is that when the inverter outputs this vector acting on the motor, at the next sampling time, the quadrature and direct axis current components reach the reference values.

[0087] The steps to obtain the two basic virtual voltage vectors used to synthesize the dynamic virtual voltage vector are as follows: ​​​​​​​​​​​​

[0088] Transform the reference voltage vector to the α-β coordinate system:

[0089]

[0090] Where θ is the rotor electrical angle; This is the voltage reference value in the dq coordinate system of the fundamental wave plane; This is the voltage reference value in the α-β coordinate system of the fundamental wave plane.

[0091] The reference voltage vector can be expressed as:

[0092] The angle of the reference voltage vector in the α-β plane is:

[0093]

[0094] Based on the sector divisions and corresponding angles in Table 1, θ can be determined. ref The sector to which it belongs is thus used to obtain two basic virtual voltage vectors for synthesizing the dynamic virtual voltage vector. and Where p = m + 1, m is the sector number, and when m is 18, p is 1.

[0095] because and These are all virtual voltage vectors, which do not contain harmonic components. Therefore, we can use the formula obtained from the fundamental plane and do not need to consider harmonics.

[0096] The steps to obtain the action ratio of the two basic virtual voltage vectors are as follows:

[0097] Define θ rela The relative angle of the reference voltage vector within the sector is calculated as follows:

[0098] θ rela =θ ref -ε

[0099] Where ε is the starting angle of the sector where the reference voltage vector is located.

[0100] like Figure 3 In the illustrated embodiment, if the obtained θ ref Given a value of 24°, according to Table 1, sector 1 is selected. At this point, ε is 10°, and θ... rela It is 14°;

[0101] Subsequently, the ratio of the two basic virtual voltage vectors is calculated as follows:

[0102]

[0103] Where σ is the angle occupied by each sector. For a nine-phase motor, since it is divided into 18 sectors on average, σ is 20°.

[0104] therefore, Figure 3 Temporary voltage vector V in temp It can be represented as:

[0105]

[0106] The steps to obtain the duration of action of the zero vector V0 are as follows:

[0107] The zero vector V0 is used to adjust the radial amplitude of the voltage vector; therefore, V is obtained. temp The duty cycle within a sampling period is supplemented by V0 for the remaining time;

[0108] V temp The duty cycle is calculated as follows:

[0109]

[0110] The duty cycle δ is in the range of 0 ≤ δ ≤ 1, s v s0 and s0 are respectively V temp i when interacting with V0 q The current slope is calculated as follows:

[0111]

[0112]

[0113] in, Voltage vector V temp Cross-axis components in the fundamental plane; It is the value after delay compensation for the fundamental plane quadrature-axis current component; This is the value after delay compensation for the direct-axis current component in the fundamental plane. The above-mentioned delay compensation and reference voltage vector calculation process are implemented using existing technical solutions.

[0114] At this time, the duration of action of the zero vector V0 is T. s ·(1-δ).

[0115] The steps to obtain the dynamic virtual voltage vector are as follows:

[0116] Online synthesized dynamic virtual voltage vector DV 3 It can be obtained from the two selected fundamental virtual vectors and one zero vector according to their respective action ratios, that is:

[0117]

[0118] like Figure 3As shown, the DV output at this time 3 With V ref The overlap eliminates control errors.

[0119] Figure 4 The diagram shows the control effect of the fundamental plane quadrature-axis current component after applying the dynamic virtual voltage vector obtained by the method of the embodiments of this application.

[0120] Figure 5 The diagram shows the control effect of the fundamental plane direct-axis current component after applying the method of the embodiments of this application to obtain the dynamic virtual voltage vector.

[0121] Depend on Figure 3 , Figure 4 and Figure 5 As can be seen, the method according to the embodiments of this application can easily and quickly obtain each basic voltage vector used to synthesize the dynamic virtual voltage vector and its action time, avoiding the process of iterative optimization and introducing weighting factors that increase the computational burden; the obtained dynamic virtual voltage vector can achieve arbitrary adjustment of amplitude and angle, achieve complete overlap with the reference voltage vector, and eliminate control error.

[0122] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 6 As shown, the computer device includes a processor, memory, and a network interface connected via a system bus. The processor provides computing and control capabilities. The memory includes a non-volatile storage medium and internal memory. The non-volatile storage medium stores an operating system, computer programs, and a database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage medium. The database stores static and dynamic information data. The network interface communicates with external terminals via a network connection. When the computer program is executed by the processor, it implements the steps in the above method embodiments.

[0123] Those skilled in the art will understand that Figure 6 The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the computer device to which the present invention is applied. A specific computer device may include more or fewer components than those shown in the figure, or combine certain components, or have different component arrangements.

[0124] In one embodiment, a computer device is also provided, including a memory and a processor, wherein the memory stores a computer program, and the processor executes the computer program to implement the steps in the above method embodiments.

[0125] In an embodiment, a computer readable storage medium is provided, having stored thereon a computer program which, when executed by a processor, implements the steps of the above method embodiments.

[0126] A person of ordinary skill in the art can understand that all or part of the processes in the above-mentioned embodiments can be completed by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer readable storage medium and can include the processes of the above-mentioned embodiments when executed. Any reference to memory, storage, database or other medium used in the embodiments of the present application can include at least one of non-volatile and volatile memory. Non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory or optical memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM can be in various forms such as static random access memory (SRAM) or dynamic random access memory (DRAM).

[0127] The present application is not limited to the structures described above and shown in the drawings, and various modifications and changes can be made without departing from the scope thereof. The scope of the present application is limited only by the appended claims.

Claims

1. A dynamic virtual voltage vector synthesis method in a model predictive control of a multiphase permanent magnet motor, characterized in that, The method comprises the following steps: According to the angle of the reference voltage vector, determine the sector where it is located, and obtain two basic virtual voltage vectors, the two basic virtual voltage vectors are obtained by the following steps: Transform the reference voltage vector into the α-β coordinate system: Wherein, θ is the rotor electric angle; Vrefd is the voltage reference value in the fundamental plane d-q coordinate system; Vrefα is the voltage reference value in the fundamental plane α-β coordinate system; The reference voltage vector is represented as: The angle of the reference voltage vector in the α-β plane is: determining θ ref the sector in which the motor is located, two basic virtual voltage vectors are obtained and where p = m + 1, m is the sector number; Based on the relative angle of the reference voltage vector in the sector, determine the ratio of action of the two basic virtual voltage vectors, the duration of action of the zero vector, and the relative angle θ of the reference voltage vector in the sector. rela Obtained through the following method: θ rela =θ ref -ε, where ε is the starting angle of the sector where the reference voltage vector is located; the ratio η of the two basic virtual voltage vectors is obtained in the following way: Where σ is the angle occupied by each sector; According to the two basic virtual voltage vectors and a zero vector, obtain a dynamic virtual voltage vector.

2. The dynamic virtual voltage vector synthesis method in the model predictive control of a multiphase permanent magnet motor according to claim 1, characterized in that, The action time of the zero vector is obtained by the following steps: Firstly, according to two basic virtual voltage vectors and acting proportion, a temporary voltage vector V temp is obtained Then, a temporary voltage vector V temp The duty ratio in one sampling period, the rest of the time is supplemented by zero vector V0, the action time of zero vector V0 is obtained.

3. The dynamic virtual voltage vector synthesis method in the model predictive control of a multiphase permanent magnet motor according to claim 2, characterized in that, The temporary voltage vector V temp is obtained by the following equation:

4. The dynamic virtual voltage vector synthesis method in the model predictive control of a multiphase permanent magnet motor according to claim 3, characterized in that, The temporary voltage vector V temp The duty cycle δ in one sampling period is obtained by the following steps: Where T s is the sampling period, the duty cycle δ ranges from 0 to 1, s v and s0 are the current slopes when V temp and V0 are applied, respectively, and i q is the current, with the calculation formula as follows: wherein is a temporary voltage vector V temp is the quadrature axis component on the fundamental plane, R s is the stator resistance, ψ f is the permanent magnet flux linkage, ω e is the rotor electrical angular velocity, i q and i d are the quadrature axis and direct axis current components on the fundamental plane, respectively, L q is the quadrature axis inductance component on the fundamental plane; is a reference value of the quadrature axis current component on the fundamental plane; is a delayed compensated value of the quadrature axis current component on the fundamental plane; is a delayed compensated value of the direct axis current component on the fundamental plane.

5. The dynamic virtual voltage vector synthesis method in the model predictive control of a multiphase permanent magnet motor according to claim 4, characterized in that, said dynamic virtual voltage vector DV 3 by the following steps: 6.A computer device, comprising a memory and a processor, wherein the memory stores a computer program, and the computer device is configured to perform the method according to any one of claims 1-5 when the computer program is executed by the processor. The processor executes the computer program to realize the steps of the method in any one of claims 1 to 5.

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