Model Predictive Control Method and Driver for Open-Winding Three-Phase Permanent Magnet Synchronous Motor

Abstract

This paper provides a model predictive control method and a driver for an open-winding three-phase permanent magnet synchronous motor. The method includes: real-time collecting the operating parameters of the permanent magnet synchronous motor and calculating to obtain the reference control voltage of the permanent magnet synchronous motor; determining the target control voltage according to the reference control voltage and a preset virtual voltage vector space, where the preset virtual voltage vector space is a plurality of virtual voltage vectors determined by preset synthesis rules for the three-phase voltage vectors corresponding to all switch states of the permanent magnet synchronous motor, and each virtual voltage vector has no zero-sequence component; determining the switch state corresponding to the target control voltage, and further driving the permanent magnet synchronous motor to operate. This paper can achieve stable current control without a complex space vector pulse width modulation strategy, improving the control ability of the motor.

Description

Technical Field

[0001] This document belongs to the field of motor systems and control, and specifically relates to a model predictive control method and a driver for an open-winding three-phase permanent magnet synchronous motor. Background Art

[0002] For an open-winding structure motor, the neutral point of a traditional three-phase AC motor is opened to form an open-winding structure with a double-port. The magnetic circuit and structure of the motor remain unchanged. The open-winding structure motor does not change the basic performance of the traditional motor. And since the constraint relationship between the traditional phase windings no longer exists after the neutral point is opened, each phase winding is independent, which can improve the reliability of the motor body to a certain extent.

[0003] In the prior art, for the control of an open-winding three-phase permanent magnet synchronous motor, the main method is to adopt a Space Vector Pulse Width Modulation (SVPWM) scheme. It divides the basic voltage vectors corresponding to the existing switching states into different sectors. When synthesizing a certain vector, first decompose this vector into the two closest basic voltage vectors, and then represent it with these two basic voltage vectors. The basic voltage vectors are used to synthesize the required voltage vector according to different time ratios, so as to ensure that the generated voltage waveform is approximately sinusoidal. However, this method does not eliminate the effect of the zero-sequence voltage component of the basic voltage vector. Furthermore, the zero-sequence current harmonics generated by the zero-sequence voltage component bring relatively large torque fluctuations, thus affecting the operation of the motor. Therefore, how to improve the control efficiency of the three-phase permanent magnet synchronous motor and enhance the control performance has become a technical problem that needs to be solved urgently at present. Summary of the Invention

[0004] Aiming at the above problems of the prior art, the purpose of this document is to provide a model predictive control method and a driver for an open-winding three-phase permanent magnet synchronous motor, which can improve the control efficiency of the three-phase permanent magnet synchronous motor.

[0005] To solve the above technical problems, the specific technical solutions of this document are as follows:

[0006] On the one hand, this document provides a model predictive control method for an open-winding three-phase permanent magnet synchronous motor, and the method includes:

[0007] Real-time collect the operating parameters of the permanent magnet synchronous motor, and calculate and obtain the reference control voltage of the permanent magnet synchronous motor;

[0008] According to the reference control voltage and a preset virtual voltage vector space, determine the target control voltage. The preset virtual voltage vector space is a plurality of virtual voltage vectors determined by the three-phase voltage vectors corresponding to all the switching states of the permanent magnet synchronous motor, and each virtual voltage vector has no zero-sequence component;

[0009] Determine the corresponding switching state according to the target control voltage, and then drive the permanent magnet synchronous motor to work.

[0010] Further, the preset virtual voltage vector space is determined through the following steps:

[0011] Determine the three-phase voltage vectors corresponding to all the switching states of the permanent magnet synchronous motor within each control period;

[0012] According to the three-phase voltage vectors and the preset synthesis rule, determine the initial virtual voltage vector space including multiple virtual voltage vectors, and each of the virtual voltage vectors has no zero-sequence component;

[0013] Divide the initial virtual voltage vector space into multiple voltage vector modulation regions

[0014] Divide each of the voltage vector modulation regions into multiple voltage vector modulation sub-regions, so as to form the preset virtual voltage vector space.

[0015] Further, the determining the initial virtual voltage vector space including multiple virtual voltage vectors according to the three-phase voltage vectors and the preset synthesis rule includes:

[0016] Obtain the first voltage vectors with a first amplitude in the three-phase voltage vectors, and the zero voltage vectors with opposite-direction zero-sequence components to each of the first voltage vectors;

[0017] Synthesize each first voltage vector and its corresponding zero voltage vector, and make the zero-sequence component of the synthesized voltage vector zero through a preset action time ratio, so as to form multiple first virtual voltage vectors;

[0018] Obtain multiple second voltage vectors without zero-sequence components and with a second amplitude in the three-phase voltage vectors, and use them as the second virtual voltage vectors;

[0019] According to the multiple first virtual voltage vectors and the multiple second virtual voltage vectors, form the initial virtual voltage vector space including multiple virtual voltage vectors.

[0020] Further, the dividing each of the voltage vector modulation regions into multiple voltage vector modulation sub-regions includes:

[0021] Determine multiple voltage vector modulation regions formed by cross-setting the first virtual voltage vectors and the second virtual voltage vectors, and each of the voltage vector modulation regions is a fan-shaped region determined by the first virtual voltage vectors and the second virtual voltage vectors as sides;

[0022] Divide the sector region into multiple voltage vector modulation sub-regions according to the preset division rules, and the vertices of each voltage vector modulation sub-region are set on the side of the sector region.

[0023] Further, determining the target control voltage according to the reference control voltage and the preset virtual voltage vector space includes:

[0024] Determine the voltage vector modulation region where the reference control voltage is located according to the operating parameters and the preset virtual voltage vector space;

[0025] Determine the voltage vector modulation region where the reference control voltage is located according to the amplitude of the reference control voltage and the voltage vector modulation region;

[0026] Determine the candidate discrete voltage vectors corresponding to the vertices of the voltage vector modulation sub-region according to the voltage vector modulation sub-region;

[0027] Calculate the evaluation value of each candidate discrete voltage vector through a value function according to the candidate discrete voltage vector and the reference control voltage;

[0028] Determine the candidate discrete voltage vector with the minimum evaluation value as the target control voltage.

[0029] Further, determining the voltage vector modulation region where the reference control voltage is located according to the operating parameters and the preset virtual voltage vector space;

[0030] Calculate the direct-axis component and quadrature-axis component of the reference control voltage of the permanent magnet synchronous motor according to the operating parameters through the voltage-current parameter equation;

[0031] Calculate the stator current position angle of the motor according to the direct-axis component and quadrature-axis component of the reference control voltage and the motor rotor position angle;

[0032] Determine the voltage vector modulation region where the reference control voltage is located according to the stator current position angle of the motor and the preset virtual voltage vector space.

[0033] Further, calculating the evaluation value of each candidate discrete voltage vector through a value function according to the candidate discrete voltage vector and the reference control voltage includes:

[0034] Calculate the direct-axis component and quadrature-axis component of each candidate discrete voltage vector according to the candidate discrete voltage vector;

[0035] Calculate the evaluation value of each candidate discrete voltage vector through a value function according to the direct-axis component and quadrature-axis component of each candidate discrete voltage vector and the reference control voltage.

[0036] Further, the calculation for obtaining the reference control voltage of the permanent magnet synchronous motor includes:

[0037] Calculating and obtaining the direct-axis component and the quadrature-axis component of the reference control voltage of the permanent magnet synchronous motor according to the operating parameters through a voltage-current parameter equation;

[0038] Determining the reference control voltage of the permanent magnet synchronous motor according to the direct-axis component and the quadrature-axis component of the reference control voltage.

[0039] On the other hand, this article also provides a driver, which includes: the driver is used to drive an open-winding three-phase permanent magnet synchronous motor, a memory, and a controller;

[0040] A computer program that can run on the controller is stored on the memory;

[0041] When the controller executes the computer program, the control method described above is implemented.

[0042] Finally, this article also provides a motor system, which includes an open-winding three-phase permanent magnet synchronous motor and the driver described above.

[0043] With the above technical solution, the model predictive control method and the driver for the open-winding three-phase permanent magnet synchronous motor described in this article simplify the voltage vector synthesis in the voltage vector space of the open-winding three-phase permanent magnet synchronous motor into a virtual voltage vector space including multiple voltage vector modulation sub-regions, thereby realizing the fast and accurate modulation of the reference control voltage, avoiding the influence of the zero-sequence voltage component of the voltage vector, and being able to quickly and reliably achieve stable current control compared with the existing complex space vector pulse width modulation strategy.

[0044] To make the above and other purposes, features, and advantages of this article more obvious and understandable, the following specifically gives preferred embodiments and, in conjunction with the accompanying drawings, the detailed description is as follows. Description of the Drawings

[0045] To more clearly illustrate the technical solutions in the embodiments of this article or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of this article. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0046] Figure 1 Shows the step schematic diagram of the model predictive control method for the open-winding three-phase permanent magnet synchronous motor in the embodiments of this article;

[0047] Figure 2Shows the schematic diagram of the determination steps of the preset virtual voltage vector space in the embodiments of the present invention;

[0048] Figure 3 Shows the schematic diagram of the determination steps of the initial virtual voltage vector space in the embodiments of the present invention;

[0049] Figure 4 Shows the schematic diagram of the determination steps of the target control voltage in the embodiments of the present invention;

[0050] Figure 5 Shows the schematic diagram of the model predictive control principle of the open - winding three - phase permanent magnet synchronous motor in the embodiments of the present invention;

[0051] Figure 6 Shows the simplified schematic diagram of the voltage vector space;

[0052] Figure 7 Shows the schematic diagram of the virtual voltage vector adjustment sub - region in the embodiments of the present invention;

[0053] Figure 8 Shows the modulation schematic diagram of the target control voltage in the embodiments of the present invention;

[0054] Figure 9 Shows the schematic diagram of the structure of the model predictive control device for the open - winding three - phase permanent magnet synchronous motor in the embodiments of the present invention;

[0055] Figure 10 Shows the schematic diagram of the structure of the computer room equipment provided in the embodiments of the present invention.

[0056] Explanation of the reference numerals in the drawings:

[0057] 100, Reference control voltage calculation module;

[0058] 200, Target control voltage determination module;

[0059] 300, Driving module;

[0060] 1002, Computer device;

[0061] 1004, Processor;

[0062] 1006, Memory;

[0063] 1008, Driving mechanism;

[0064] 1010, Input / output module;

[0065] 1012, Input device;

[0066] 1014, Output device;

[0067] 1016, Rendering device;

[0068] 1018, Graphical User Interface;

[0069] 1020, Network Interface;

[0070] 1022, Communication Link;

[0071] 1024, Communication Bus. Detailed Implementation Manner

[0072] Next, the technical solutions in the embodiments of this article will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of this article. Obviously, the described embodiments are only a part of the embodiments of this article, rather than all the embodiments. Based on the embodiments in this article, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of this article.

[0073] It should be noted that the terms "first", "second", etc. in the specification and claims of this article and the above-mentioned drawings are used to distinguish similar objects, and do not necessarily need to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of this article described here can be implemented in an order other than those illustrated or described here. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, device, product, or equipment that includes a series of steps or units does not necessarily need to be limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or are inherent to these processes, methods, products, or equipment.

[0074] In the prior art, the control of the open-winding three-phase permanent magnet synchronous motor mainly adopts the space vector pulse width modulation scheme, which divides the existing voltage basic vectors corresponding to the switching states into different sectors. When synthesizing a certain vector, first decompose this vector into the two voltage basic vectors closest to it, and then use these two basic voltage vectors to represent it. The voltage basic vectors are used to synthesize the required voltage vector according to different time ratios, so as to ensure that the generated voltage waveform is approximately a sine wave. However, this method does not eliminate the action of the zero-sequence voltage component of the voltage basic vector, and then the zero-sequence current harmonics generated by the zero-sequence voltage component bring relatively large torque fluctuations, thus affecting the operation of the motor.

[0075] To solve the above problems, the embodiments of this article provide a model predictive control method for an open-winding three-phase permanent magnet synchronous motor, which can improve the control efficiency of the three-phase permanent magnet synchronous motor. As Figure 5As shown in the figure, it is the schematic diagram of model predictive control in this method. The voltage vectors corresponding to the switch states are pre-simplified and partitioned to obtain a virtual voltage vector space. Then, through the acquisition of motor operating parameters, coordinate transformation, and model prediction, the reference control voltage is obtained. Furthermore, through the pre-partitioned virtual voltage vector space, the reference control voltage is modulated to obtain the target control voltage. Then, based on the target control voltage, the closed-loop control of the motor is realized. In this paper, a stable current control can be achieved without a complex space vector pulse width modulation strategy, improving the control ability of the motor.

[0076] Figure 1 Figure is the schematic diagram of the steps of a model predictive control method for an open-winding three-phase permanent magnet synchronous motor provided by an embodiment of this paper. This specification provides the method operation steps as described in the embodiment or flowchart, but based on routine or non-creative labor, it may include more or fewer operation steps. The step order listed in the embodiment is only one way among the execution orders of numerous steps and does not represent the only execution order. When the actual system or device product executes, it can be executed in the method order shown in the embodiment or the accompanying drawings or executed in parallel. Specifically, as Figure 1 shown, the method may include:

[0077] S101: Real-time collect the operating parameters of the permanent magnet synchronous motor and calculate to obtain the reference control voltage of the permanent magnet synchronous motor;

[0078] S102: Determine the target control voltage according to the reference control voltage and the preset virtual voltage vector space. The preset virtual voltage vector space is multiple virtual voltage vectors determined by the three-phase voltage vectors corresponding to all the switch states of the permanent magnet synchronous motor, and each virtual voltage vector has no zero-sequence component;

[0079] S103: Determine the switch state corresponding to the target control voltage, and then drive the permanent magnet synchronous motor to operate.

[0080] It can be understood that in this paper, according to the real-time operating parameters of the permanent magnet synchronous motor, combined with the existing prediction model (i.e., the parameter equation of motor voltage and current), the reference control voltage of the motor is calculated. Then, the target control voltage is obtained according to the preset virtual voltage vector space, and the switch state is adjusted according to the target control voltage, so as to realize the fast and efficient control of the motor. In this paper, the preset virtual voltage vector space is a modulation space formed by multiple virtual voltage vectors synthesized from the three-phase voltage vectors corresponding to the switch states, and each virtual voltage vector has no zero-sequence component. In this way, the influence of the zero-sequence component can be avoided when controlling the output voltage, thereby improving the stability of the motor operation and realizing stable current control.

[0081] Among them, the working parameters may be the working voltage of the DC bus, the real-time three-phase stator current value, the motor rotor position angle, and the target rotor electrical angular velocity. Of course, there may also be other parameter information, which is not limited in the embodiments of this specification.

[0082] Among them, the target rotor electrical angular velocity is obtained through the following steps:

[0083] Obtain the motor rotor position angles at adjacent moments, and calculate the difference in the motor rotor position angles at these adjacent moments;

[0084] Calculate the ratio obtained by dividing the difference in the motor rotor position angles by the time difference at these adjacent moments, and use this ratio as the motor mechanical rotor angular velocity;

[0085] Multiply the motor mechanical rotor angular velocity by the number of pole pairs of the motor as the target rotor electrical angular velocity.

[0086] Among them, the mechanical rotor angular velocity represents the change in the motor rotor position angle, and the number of pole pairs of the motor is determined by the electrode topology and can be obtained according to the actual situation.

[0087] The DC bus voltage can be obtained by collecting through a voltage sensor, the real-time three-phase stator current value can be obtained by collecting through a current sensor, such as through a stator three-phase current sensor, and the motor rotor position angle can be obtained by collecting through a rotor optical encoder. In some other embodiments, there may also be other collection devices, which are not elaborated in the embodiments of this specification.

[0088] It should be noted that the above working parameters are sampling data in the three-phase stationary abc coordinate system. In this specification, transformations between the two-phase stationary αβ0 coordinate system and the two-phase rotating dq0 coordinate system are required, and then a reasonable control method is selected through the prediction model provided above for control. For the three common coordinate systems, usually the a-axis in the three-phase stationary coordinate system is taken as the reference, the α-axis coincides with the a-axis, and the β-axis leads by a phase angle of 90°. The angle between the d-axis and the a-axis is defined as the motor rotor position angle θ, and the dq0 coordinate system rotates at the rotor electrical angular velocity. The transformation coefficients between the three-phase stationary coordinate system and the two-phase stationary coordinate system also take different values according to equal-power transformation and equal-amplitude transformation. For example, Clark transformation and Park transformation with equal amplitudes are used, and the corresponding setting methods are selected according to the actual situation, which are not limited in this specification.

[0089] In actual work, after obtaining the motor rotor position angle θ, the rotor electrical angular velocity ω can be obtained through a differential process e ; and then through the rotor electrical angular velocity ω e After taking the difference between the rotor electrical angular velocity ω and the target rotor electrical angular velocity and passing through a PI regulator, the given value i of the motor q-axis (quadrature axis) current is obtained qref, and then the three-phase stator winding currents \(i\) obtained by acquisition A , \(i\) B , \(i\) C , are combined with the rotor position information and after abc-dq coordinate transformation, the (direct axis) d-axis and (quadrature axis) q-axis feedback current values \(i\) d , \(i\) q are obtained. Finally, the above data are combined with the voltage prediction model to calculate the d-axis and q-axis voltage values \(u\) qref , \(u\) qref , and through dq-αβ transformation, the α-axis and β-axis voltage values \(u\) α , \(u\) β are obtained to synthesize the reference control voltage.

[0090] Optionally, the voltage prediction model can be expressed by the following formula (1):

[0091]

[0092] where \(u\) dref and \(u\) qref are the direct axis component and quadrature axis component of the reference control voltage, \(L\) d and \(L\) q are the inductances of the motor on the direct axis and quadrature axis, \(i\) dref is the direct axis given value of the motor stator current. Preferably, \(i\) dref = 0, \(i\) qref is the quadrature axis given value of the motor stator current, \(R\) s is the resistance of the motor, \(T_s\) is the control cycle time of the controller, \(\omega\) e is the electrical angular velocity of the motor, \(\varPsi\) f is the magnetic flux of the motor permanent magnet, \(i\) d (k) is the direct axis component after coordinate transformation of the real-time current of the motor in the current cycle, \(i\) d (k) is the quadrature axis component after coordinate transformation of the real-time current of the motor in the current cycle.

[0093] In the embodiment of this specification, through the above formula (1) combined with the real-time working parameters and target requirements of the motor (such as the target rotor electrical angular velocity), the direct axis component and quadrature axis component of the reference control voltage of the three-phase permanent magnet synchronous motor in the dq coordinate system can be calculated. Furthermore, according to the dq-αβ transformation, the α-axis and β-axis voltage values \(U\) α , \(U\) β are obtained to synthesize the rotating voltage vector, that is, the reference voltage vector required in this article.

[0094] In the existing technology, during the voltage vector synthesis process, it is directly synthesized through the vector voltages corresponding to the switch states. Therefore, only the synthesis process of the two-phase vectors on the α-axis and β-axis is considered, and the zero-sequence voltage corresponding to each voltage vector is not considered for the current harmonics generated during the operation of the motor, resulting in a large torque fluctuation and reducing the stability of the motor operation.

[0095] Therefore, in order to improve the stability of the motor operation and make full use of the motor performance, the embodiments of this specification optimize the voltage vectors corresponding to the switch states to obtain a preset virtual voltage vector space, which can realize the modulation of the reference control voltage and improve the stability of the motor and its operating equipment. Optionally, as Figure 2 shown, the preset virtual voltage vector space can be determined through the following steps:

[0096] S201: Determine the three-phase voltage vectors corresponding to all the switch states of the permanent magnet synchronous motor in each control period;

[0097] S202: According to the three-phase voltage vectors and the preset synthesis rules, determine an initial virtual voltage vector space containing multiple virtual voltage vectors, and each virtual voltage vector has no zero-sequence component;

[0098] S203: Divide the initial virtual voltage vector space into multiple voltage vector modulation regions;

[0099] S204: Divide each voltage vector modulation region into multiple voltage vector modulation sub-regions, thereby forming the preset virtual voltage vector space.

[0100] Among them, the open-winding three-phase permanent magnet synchronous motor with six bridge arms is adopted in this specification. Therefore, it has 64 switch states, and theoretically corresponds to 64 voltage vectors. However, in actual situations, there will be repeated voltage vectors, that is, different switch states correspond to the same voltage vector. Therefore, in this article, 64 switch states correspond to 27 voltage vectors. As shown in part a of Figure 6 , it is a schematic diagram of the αβ plane voltage vector space, and the zero-sequence voltage corresponding to each voltage vector is different. As shown in Table 1 below, it is the zero-sequence voltage and its corresponding voltage vector switch states in this article:

[0101] Table 1

[0102]

[0103] Among them, the numbers in parentheses correspond to the switch states, which are composed of two groups of three - bit binary numbers. The first digit of the number corresponds to the first group of binary numbers, and the second digit corresponds to the second group of binary numbers. For example, O(70) represents the voltage vector corresponding to the switch state (111000). 1 indicates that the corresponding bridge arm is in the upper - tube conduction state, and 0 indicates that the corresponding bridge arm is in the lower - tube conduction state.

[0104] As can be seen from Table 1 above, the voltage vectors corresponding to different switch states have different zero - sequence voltages (i.e., zero - sequence components). Therefore, when synthesizing virtual voltage vectors, through preset rules, virtual voltage vectors without zero - sequence components can be formed based on the positional relationship and amplitude relationship between different voltage vectors. This can not only consider the switch states corresponding to the switch states but also avoid the influence of current harmonics during actual voltage control, improving the further utilization of motor performance.

[0105] Based on different virtual voltage vectors without zero - sequence components, in order to facilitate the conversion of the calculated d - axis and q - axis voltage components and the further synthesis of the reference control voltage, by setting the voltage - vector modulation region and dividing the voltage - vector modulation sub - regions, finer - grained modulation of the reference control voltage can be achieved, improving the stability and reliability of the control.

[0106] As Figure 6 shown in part a and Table 1 above, the fundamental - wave (αβ) voltage - vector spatial structure composition of the six - bridge - arm three - phase permanent - magnet synchronous motor provided by the embodiments of this specification is as follows. The vertices of the largest hexagon are the largest voltage vectors (such as OM, ON, OP, OQ, OR, OS), and the absolute value of the amplitude of the corresponding zero - sequence voltage is 1 / 3U dc , the mid - points of the six sides of this hexagon are the second - largest voltage vectors (such as OG, OH, OI, OJ, OK, OL), and the amplitude of the corresponding zero - sequence voltage is 0, that is, the second - largest voltage vectors have no zero - sequence voltage; and the zero - voltage vector (such as OO) is at the center of the hexagon, and the absolute value of the amplitude of the corresponding zero - sequence voltage is U dc where U dc is the DC - bus voltage.

[0107] Specifically, in order to clarify the synthesis process of virtual voltage vectors, as an option, as Figure 3 shown, determining the initial virtual voltage - vector space containing multiple virtual voltage vectors according to the three - phase voltage vectors and the preset synthesis rules includes:

[0108] S301: Obtain the first voltage vector with the first amplitude among the three - phase voltage vectors, and the zero - voltage vector with the zero - sequence component in the opposite direction to each first voltage vector;

[0109] S302: Synthesize each first voltage vector with its corresponding zero voltage vector, and make the zero-sequence component of the synthesized voltage vector zero through a preset action time ratio, thereby forming a first virtual voltage vector;

[0110] S303: Obtain multiple second voltage vectors with a second amplitude and no zero-sequence component in the three-phase voltage vectors, and use them as second virtual voltage vectors;

[0111] S304: According to multiple said first virtual voltage vectors and multiple said second virtual voltage vectors, form an initial virtual voltage vector space containing multiple virtual voltage vectors.

[0112] Among them, the first amplitude can be the voltage vector with the largest amplitude on the fundamental wave plane (such as OM, ON, OP, OQ, OR, OS), because the corresponding zero-sequence voltage amplitude is 1 / 3U dc , in order to cancel the zero-sequence voltage on this voltage vector, it is possible to select a synthesis with the zero voltage vector (such as OO, whose zero-sequence voltage amplitude is U dc ), and the zero-sequence voltage direction of this zero voltage vector is opposite to the zero-sequence voltage vector direction of the first voltage vector. The action time within one cycle is 3:1. In this way, the zero-sequence component of the synthesized first virtual voltage vector is zero, and its amplitude on the fundamental wave (αβ) plane remains unchanged. Therefore, there are 6 maximum voltage vectors, so 6 first virtual voltage vectors can be synthesized. Correspondingly, then select the second largest voltage vector as the second voltage vector. Since it has no zero-sequence voltage, it can be directly used as the second virtual voltage vector. A total of 6 second virtual voltage vectors can be obtained, so a simplified virtual voltage vector space can be obtained.

[0113] Exemplarily, for a six-bridge-arm three-phase permanent magnet synchronous motor, through the above synthesis process, a virtual voltage vector space formed by 12 virtual voltage vectors can be obtained, as shown in part b of Figure 6 . Since the amplitudes of the synthesized first virtual voltage vector and the second virtual voltage vector on the fundamental wave plane do not change, the target control voltage can be modulated on the basis of the above hexagon. Moreover, the above hexagon is the limit vector of the inverter. In this paper, 12 synthesized virtual voltage vectors without zero-sequence voltage are used. In this way, when modulating, there is no need to consider the zero-sequence axis, and only the fundamental wave component needs to be considered during modulation. At the same time, the maximum utilization rate of the voltage vector can be achieved, the control performance of the open-winding three-phase motor is improved, and the performance advantages of the open-winding three-phase motor are fully utilized, and the reliability of the motor performance is improved.

[0114] To further improve the modulation granularity of the target control voltage, optionally, the dividing each voltage vector modulation region into multiple voltage vector modulation sub-regions includes:

[0115] Determine a plurality of voltage vector modulation regions formed by cross - setting a first virtual voltage vector and a second virtual voltage vector, wherein each of the voltage vector modulation regions is a sector region determined by the first virtual voltage vector and the second virtual voltage vector as sides;

[0116] According to a preset division rule, divide the sector region into a plurality of voltage vector modulation sub - regions, and the vertices of each of the voltage vector modulation sub - regions are set on the sides of the sector region.

[0117] It can be understood that by further dividing each voltage vector modulation region, the modulation of the reference control voltage can be realized on each voltage vector modulation sub - region, so as to obtain a target control voltage with smaller and more accurate granularity. As Figure 7 and Figure 8 shown, it is an embodiment of the division of the voltage vector modulation sub - regions, where the two virtual voltage vectors are u1 and u2 respectively; equally - spaced division is performed at a certain interval to form a plurality of isosceles trapezoids (or triangles) with the same height. The height of each trapezoid is h1, where h1=(1 / N)·U dc , U dc is the DC bus voltage of the controller. Thus, N voltage vector modulation sub - regions can be obtained. Optionally, for better illustration of this embodiment, N = 5. In this way, each voltage vector modulation region can obtain 5 voltage vector modulation sub - regions, and the vertices of each voltage vector modulation sub - region are on the virtual voltage vectors u1 and u2. The vector number of each vertex can be (a, b), where a represents the vector amplitude size and b represents the vector position. Taking the region where u1 and u2 are located as an example, its discrete voltage vector comparison table is shown in Table 2.

[0118] Table 2

[0119] Vertex number Discrete voltage vector (1,1) <![CDATA[u0]]> (2,1) <![CDATA[0.8u0+0.2u1]]> (3,1) <![CDATA[0.6u0+0.4u1]]> (4,1) <![CDATA[0.4u0+0.6u1]]> (5,1) <![CDATA[0.2u0+0.8u1]]> (6,1) <![CDATA[u1]]> (2,2) <![CDATA[0.8u0+0.2u2]]> (3,2) <![CDATA[0.6u0+0.4u2]]> (4,2) <![CDATA[0.4u0+0.6u2]]> (5,2) <![CDATA[0.2u0+0.8u2]]> (6,2) <![CDATA[u2]]>

[0120] Among them, u0 is the DC bus voltage, u1 is the second virtual voltage vector, and u1 is the first virtual voltage vector. Through the above steps, the voltage vector expression of each vertex of each voltage vector modulation sub - region in the virtual voltage vector space can be determined, and this voltage vector expression can be represented by known voltage vectors (such as the synthesized first virtual voltage vector and second virtual voltage vector, and the zero voltage vector). That is to say, any determined discrete voltage vector can be accurately represented by known voltage vectors according to certain weights.

[0121] The above is a way to divide the voltage vector modulation sub-region in this specification. In some other embodiments, there may be other ways of division, as long as it can ensure that the vertices of the divided voltage vector modulation sub-regions are all set on the edges of the fan-shaped region of the voltage vector modulation region. Other ways of division will not be elaborated in the embodiments of this specification.

[0122] Based on the virtual voltage vector space obtained by the above steps of division, the modulation of the reference control voltage can be achieved. Optionally, as Figure 4 shown, determining the target control voltage according to the reference control voltage and the preset virtual voltage vector space includes:

[0123] S401: Determine the voltage vector modulation region where the reference control voltage is located according to the working parameters and the preset virtual voltage vector space;

[0124] S402: Determine the voltage vector modulation sub-region where the reference control voltage is located according to the amplitude of the reference control voltage and the voltage vector modulation region;

[0125] S403: Determine the candidate discrete voltage vectors corresponding to the vertices of the voltage vector modulation sub-region according to the voltage vector modulation sub-region;

[0126] S404: Calculate the evaluation value of each candidate discrete voltage vector through a value function according to the candidate discrete voltage vectors and the reference control voltage;

[0127] S405: Determine the candidate discrete voltage vector with the minimum evaluation value as the target control voltage.

[0128] It can be understood that in this specification, the calculated reference control voltage is projected into the virtual voltage vector space, so that the specific voltage vector modulation sub-region where it is located can be obtained. Furthermore, the vertices of this voltage vector modulation sub-region are used as candidate discrete voltage vectors, so as to select the candidate discrete voltage vector with the smallest deviation from the target control voltage as the target control voltage, and drive the motor controller through this voltage. In this paper, more accurate control and adjustment of the target control voltage are achieved through a smaller region, and at the same time, there is less torque ripple, improving the stability of motor operation. For example, it has great application value in some small servo scenarios.

[0129] In a further embodiment, in order to more quickly determine the position of the reference control voltage, optionally, determining the voltage vector modulation region where the reference control voltage is located according to the working parameters and the preset virtual voltage vector space includes:

[0130] According to the working parameters, the direct-axis component and the quadrature-axis component of the reference control voltage of the permanent magnet synchronous motor are calculated and obtained through the voltage-current parameter equation;

[0131] According to the direct-axis component and the quadrature-axis component of the reference control voltage, and the motor rotor position angle, the motor stator current position angle is calculated and obtained;

[0132] According to the motor stator current position angle and the preset virtual voltage vector space, the voltage vector modulation region where the reference control voltage is located is determined.

[0133] It can be understood that the direct-axis component and the quadrature-axis component of the reference control voltage can be obtained through the above formula (1), and then the motor stator current position angle θ can be obtained by combining the following formula (2) i :

[0134] θ i = arctan(u qref / u dref ) + θ (2)

[0135] Wherein, θ i is the motor stator current position angle, and θ is the motor rotor position angle.

[0136] Since the virtual voltage vector space is realized based on the fundamental wave plane, therefore, on the basis of obtaining the motor stator current position angle, the position relationship of the reference target voltage in the virtual voltage vector space can be directly determined according to its angle value.

[0137] In the embodiments of this specification, the evaluation value of each candidate discrete voltage vector is calculated through a value function according to the candidate discrete voltage vector and the reference control voltage, including:

[0138] According to the candidate discrete voltage vector, the direct-axis component and the quadrature-axis component of each candidate discrete voltage vector are calculated and obtained;

[0139] According to the direct-axis component and the quadrature-axis component of each candidate discrete voltage vector, and the reference control voltage, the evaluation value of each candidate discrete voltage vector is calculated through a value function.

[0140] In actual work, the direct-axis component and the quadrature-axis component of the candidate discrete voltage vector in the dq coordinate system can be obtained through αβ-dq transformation, and then the evaluation value of each candidate discrete voltage vector is calculated by the value function, and the value function can be represented by the following formula (3):

[0141] g = |u d (i) - u dref | + |u q (i) - u qref| (3)

[0142] Among them, g is the evaluation value, and u d (i) is the d (direct) axis component of the candidate discrete voltage vector, and u q (i) is the q (quadrature) axis component of the candidate discrete voltage vector, and u dref is the d (direct) axis component of the reference control voltage, and u qref is the d (direct) axis component of the reference control voltage.

[0143] Through the above steps, the candidate discrete voltage vector with the smallest deviation from the reference control voltage can be obtained, and thus it is determined as the target control voltage. Based on the determination of the target control voltage, the motor can be driven to work by the weights of different switching states within a control period according to its voltage composition expression. In this paper, through the simplified processing of the voltage vector distribution form and the further fine division of the voltage vector space, more optional voltage vectors are provided for model predictive control to ensure the reliability and accuracy of the provided voltage vectors.

[0144] Based on the same inventive concept, the embodiment of this specification also provides a model predictive control device for an open-winding three-phase permanent magnet synchronous motor, as Figure 9 shown, the device includes:

[0145] A reference control voltage calculation module 100, configured to collect the working parameters of the permanent magnet synchronous motor in real time and calculate and obtain the reference control voltage of the permanent magnet synchronous motor;

[0146] A target control voltage determination module 200, configured to determine a target control voltage according to the reference control voltage and a preset virtual voltage vector space, where the preset virtual voltage vector space is a plurality of virtual voltage vectors determined by a preset synthesis rule for the three-phase voltage vectors corresponding to all switching states of the permanent magnet synchronous motor, and each virtual voltage vector has no zero-sequence component;

[0147] A driving module 300, configured to determine the switching state corresponding thereto according to the target control voltage, and further drive the permanent magnet synchronous motor to work.

[0148] The beneficial effects obtained by the above device are the same as those obtained by the above method, and will not be elaborated in the embodiments of this specification.

[0149] In some other embodiments, this paper also provides a driver, the driver includes: the driver is used to control an open-winding three-phase permanent magnet synchronous motor, and the driver includes a memory and a controller;

[0150] A computer program that can run on the controller is stored on the memory;

[0151] When the controller executes the computer program, the control method as described above is implemented.

[0152] In some other embodiments, this article also provides a motor system, which includes an open-winding three-phase permanent magnet synchronous motor and the above-mentioned driver.

[0153] In some other embodiments, this article also provides an electrical equipment, which includes the above-mentioned motor system. The electrical equipment can be a small servo equipment, such as a small robotic arm. In some other embodiments, the electrical equipment can also be an assembly line system, which is configured with a servo link including the above-mentioned motor. This article can achieve the improvement of the ultimate performance without changing the motor structure, and also solve the problem of large torque ripple during the operation of the open-winding motor.

[0154] As Figure 10 shown, a computer device provided by an embodiment of this article is provided. The computer device 1002 may include one or more processors 1004, such as one or more central processing units (CPUs), and each processing unit may implement one or more hardware threads. The computer device 1002 may also include any memory 1006, which is used to store any kind of information such as code, settings, data, etc. Non-limiting, for example, the memory 1006 may include any one or more combinations of the following: any type of RAM, any type of ROM, flash memory devices, hard disks, optical discs, etc. More generally, any memory may use any technology to store information. Further, any memory may provide volatile or non-volatile retention of information. Further, any memory may represent a fixed or removable component of the computer device 1002. In one case, when the processor 1004 executes the associated instructions stored in any memory or combination of memories, the computer device 1002 may perform any operation of the associated instructions. The computer device 1002 also includes one or more drive mechanisms 1008 for interacting with any memory, such as a hard disk drive mechanism, an optical disc drive mechanism, etc.

[0155] The computer device 1002 may also include an input / output module 1010 (I / O) for receiving various inputs (via the input device 1012) and for providing various outputs (via the output device 1014). A specific output mechanism may include a presentation device 1016 and an associated graphical user interface (GUI) 1018. In other embodiments, the input / output module 1010 (I / O), the input device 1012, and the output device 1014 may not be included, and it may only be a computer device in the network. The computer device 1002 may also include one or more network interfaces 1020 for exchanging data with other devices via one or more communication links 1022. One or more communication buses 1024 couple the components described above together.

[0156] The communication link 1022 may be implemented in any manner, for example, through a local area network, a wide area network (e.g., the Internet), a point-to-point connection, etc., or any combination thereof. The communication link 1022 may include any combination of hardwired links, wireless links, routers, gateway functions, name servers, etc. governed by any protocol or combination of protocols.

[0157] Corresponding to Figures 1 - 4 In the method, embodiments herein also provide a computer-readable storage medium having a computer program stored thereon, and when the computer program is run by a processor, the steps of the above method are executed.

[0158] Embodiments herein also provide a computer-readable instruction, and when the processor executes the instruction, the program therein causes the processor to execute the method as Figures 1 to 4 shown.

[0159] It should be understood that in various embodiments herein, the magnitudes of the serial numbers of the above processes do not mean the order of execution, and the order of execution of each process should be determined by its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments herein.

[0160] It should also be understood that in the embodiments herein, the term "and / or" is only a description of the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B may represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in this article generally represents an "or" relationship between the associated objects before and after.

[0161] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be implemented by electronic hardware, computer software, or a combination of the two. To clearly illustrate the interchangeability of hardware and software, the composition and steps of the examples have been generally described according to functions in the above description. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. Professional technicians can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this article.

[0162] Those skilled in the art can clearly understand that for the convenience and conciseness of description, the specific working processes of the systems, devices, and units described above can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated herein.

[0163] In the several embodiments provided in this article, it should be understood that the disclosed systems, devices, and methods can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the units is only a logical function division, and there can be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the displayed or discussed couplings or direct couplings or communication connections to each other can be indirect couplings or communication connections through some interfaces, devices, or units, and can also be in the form of electrical, mechanical, or other connections.

[0164] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of the embodiments in this article.

[0165] In addition, the functional units in the various embodiments of this article can be integrated into one processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated units can be implemented in the form of hardware or in the form of software functional units.

[0166] When the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution herein, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments herein. The aforementioned storage medium includes: various media that can store program codes, such as USB flash drives, mobile hard disks, read-only memories (ROM, Read-Only Memory), random access memories (RAM, Random Access Memory), magnetic disks, or optical discs.

[0167] Specific embodiments are used in this article to elaborate on the principles and implementation manners herein. The description of the above embodiments is only used to help understand the method and its core idea herein; at the same time, for those of ordinary skill in the art, according to the idea herein, there will be changes in the specific implementation manners and application scopes. In summary, the content of this specification should not be construed as a limitation to this article.

Claims

1. A model predictive control method for an open-winding three-phase permanent magnet synchronous motor, characterized in that, The method includes: Collecting the operating parameters of the permanent magnet synchronous motor in real time, and calculating and obtaining the reference control voltage of the permanent magnet synchronous motor; Determining a target control voltage according to the reference control voltage and a preset virtual voltage vector space, where the preset virtual voltage vector space is a plurality of virtual voltage vectors determined by the three-phase voltage vectors corresponding to all the switching states of the permanent magnet synchronous motor, and each virtual voltage vector has no zero-sequence component; wherein, the preset virtual voltage vector space is determined through the following steps: determining the three-phase voltage vectors corresponding to all the switching states of the permanent magnet synchronous motor within each control period; according to the three-phase voltage vectors and a preset synthesis rule, determining an initial virtual voltage vector space including a plurality of virtual voltage vectors, and each virtual voltage vector has no zero-sequence component; dividing the initial virtual voltage vector space into a plurality of voltage vector modulation regions; dividing each of the voltage vector modulation regions into a plurality of voltage vector modulation sub-regions, thereby forming the preset virtual voltage vector space; the determining an initial virtual voltage vector space including a plurality of virtual voltage vectors according to the three-phase voltage vectors and a preset synthesis rule includes: obtaining a first voltage vector with a first amplitude among the three-phase voltage vectors, and a zero voltage vector having an opposite-direction zero-sequence component to each first voltage vector; synthesizing each first voltage vector and its corresponding zero voltage vector, and making the zero-sequence component of the synthesized voltage vector zero through a preset action time ratio, thereby forming a plurality of first virtual voltage vectors; obtaining a plurality of second voltage vectors with a second amplitude and no zero-sequence component among the three-phase voltage vectors, and using them as second virtual voltage vectors; forming an initial virtual voltage vector space including a plurality of virtual voltage vectors according to the plurality of first virtual voltage vectors and the plurality of second virtual voltage vectors; Determining the switching state corresponding to the target control voltage according to the target control voltage, and further driving the permanent magnet synchronous motor to operate.

2. The method according to claim 1, wherein The dividing each of the voltage vector modulation regions into a plurality of voltage vector modulation sub-regions includes: Determining a plurality of voltage vector modulation regions formed by cross-setting of the first virtual voltage vectors and the second virtual voltage vectors, where each of the voltage vector modulation regions is a sector region determined by the first virtual voltage vectors and the second virtual voltage vectors as sides; Dividing the sector region into a plurality of voltage vector modulation sub-regions according to a preset division rule, and the vertex of each of the voltage vector modulation sub-regions is set on the side of the sector region.

3. The method according to claim 1, characterized in that, The determining a target control voltage according to the reference control voltage and a preset virtual voltage vector space includes: Determining the voltage vector modulation region where the reference control voltage is located according to the operating parameters and the preset virtual voltage vector space; Determining the voltage vector modulation sub-region where the reference control voltage is located according to the amplitude of the reference control voltage and the voltage vector modulation region; Determining a candidate discrete voltage vector corresponding to the vertex of the voltage vector modulation sub-region according to the voltage vector modulation sub-region; Calculate the evaluation value of each candidate discrete voltage vector through a cost function according to the candidate discrete voltage vector and the reference control voltage; Determine the candidate discrete voltage vector with the minimum evaluation value as the target control voltage.

4. The method according to claim 3, wherein The determining the voltage vector modulation region where the reference control voltage is located according to the operating parameters and the preset virtual voltage vector space includes: Calculate and obtain the direct-axis component and the quadrature-axis component of the reference control voltage of the permanent magnet synchronous motor through a voltage-current parameter equation according to the operating parameters; Calculate and obtain the stator current position angle of the motor according to the direct-axis component and the quadrature-axis component of the reference control voltage and the motor rotor position angle; Determine the voltage vector modulation region where the reference control voltage is located according to the stator current position angle of the motor and the preset virtual voltage vector space.

5. The method according to claim 3, wherein The calculating the evaluation value of each candidate discrete voltage vector through a cost function according to the candidate discrete voltage vector and the reference control voltage includes: Calculate and obtain the direct-axis component and the quadrature-axis component of each candidate discrete voltage vector according to the candidate discrete voltage vector; Calculate the evaluation value of each candidate discrete voltage vector through a cost function according to the direct-axis component and the quadrature-axis component of each candidate discrete voltage vector and the reference control voltage.

6. The method according to claim 1, wherein The calculating and obtaining the reference control voltage of the permanent magnet synchronous motor includes: Calculate and obtain the direct-axis component and the quadrature-axis component of the reference control voltage of the permanent magnet synchronous motor through a voltage-current parameter equation according to the operating parameters; Determine the reference control voltage of the permanent magnet synchronous motor according to the direct-axis component and the quadrature-axis component of the reference control voltage.

7. A driver, characterized in that, The driver includes: a memory and a controller; A computer program that can run on the controller is stored on the memory; When the controller executes the computer program, the control method according to any one of claims 1 to 6 is implemented.

8. A motor system, characterized in that, The system includes an open-winding three-phase permanent magnet synchronous motor and the driver according to claim 7.

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