Space vector modulation method of five-phase series end winding permanent magnet synchronous motor

Abstract

The invention relates to the technical field of motors, in particular to a space vector modulation method of a five-phase series end winding permanent magnet synchronous motor, which comprises the following steps of: drawing voltage vector distribution; dividing a maximum modulation domain; obtaining a three-dimensional space modulation domain and a two-dimensional space modulation domain, obtaining a basic voltage vector adjacent to a sub-tetrahedron where each reference voltage vector is located and a duty ratio of the basic voltage vector, and judging whether each reference voltage vector is over-modulated or not; performing overmodulation on each reference voltage vector in the three-dimensional space modulation domain and the two-dimensional space modulation domain; if the duty ratio of the upper bridge arm is larger than 1, a double-sampling-period modulation strategy is adopted for modulation; and the switch sequence is centrally symmetrical and then input to a five-phase six-bridge arm series end winding inverter. According to the method provided by the invention, the reference voltage can be tracked with relatively high precision, the harmonic current and the zero-sequence current can be effectively suppressed, and the method has relatively high DC bus voltage utilization rate.

Description

Technical Field

[0001] The invention relates to the technical field of electric motors, and in particular to a space vector modulation method for a five-phase series end winding permanent magnet synchronous motor. Background Art

[0002] In recent years, in the fields of electric vehicles, electric ship propulsion, etc., multi-phase motors have been more widely used in traction and drive applications due to their advantages over three-phase motors, such as higher reliability, wide speed regulation range, and high power density. The five-phase series end-winding permanent magnet synchronous motor, as the multi-phase motor with the smallest odd number of phases, is more favored in motor research.

[0003] In the five-phase motor drive system, the most widely used is the five-bridge half-bridge inverter, which is used to drive a five-phase motor with a single neutral point. However, this topology has the disadvantages of low DC voltage utilization, coupling between windings, and inability to control the zero axis. Therefore, a full-bridge inverter was subsequently developed. In this topology, each phase winding is independently driven by an H-bridge, the phase voltage amplitude can reach the full voltage of the DC bus voltage, and each fault phase can be easily isolated from other phases, but its high cost is also obvious. The emergence of the series-end winding inverter has made a trade-off between high performance and high cost. It can be regarded as a full-bridge inverter with multiple bridge arms, thereby reducing the number of power electronic devices. The series-end winding inverter provides a zero-sequence current path. The zero-sequence current increases the torque ripple and power loss, so its suppression is crucial, but the zero-sequence current will not flow through the middle bridge arm, thus effectively reducing the power loss of the zero-sequence current to the drive system.

[0004] At present, the mainstream modulation methods for five-phase six-bridge-arm series-end winding inverters are carrier-based pulse width modulation and space vector modulation. In the literature [1] Li A, Jiang D, Liu Z, et al. Generalized PWM methodfor series-end winding motor drive[J]. IEEE Transactions on Power Electronics, 2021, 36(4): 4452-4462, the carrier-based pulse width modulation is constrained by the equal amplitude of the bridge arm voltage. The mapping relationship between the bridge arm voltage and the phase voltage is derived through the phasor diagram to obtain the coordinate transformation matrix of the bridge arm voltage. The bridge arm voltage is modulated to generate a switching sequence after injecting a common-mode voltage into the bridge arm. In theory, the DC bus voltage utilization rate in the fundamental wave space can reach 2. Reference [2] Dong Z, Liu C, Song Z, et al. Suppression of dual-harmonic components for five-phase series-winding PMSM[J]. IEEE Transactions on Transportation Electrification, 2022, 8(1): 121-134 proposed space vector modulation to decouple modulation of both the α-β subspace and the xy subspace by synthesizing virtual voltage vectors, and also perform vector synthesis on the zero axis without affecting the α-β subspace. According to the deadbeat principle, the basic voltage vector of the synthesized reference voltage vector is determined and the duty cycle is calculated, thus achieving independent modulation of the three subspaces and effectively suppressing harmonic currents and zero-sequence currents.

[0005] However, the modulation method in the literature [1] does not provide a visual and intuitive discussion of the over-modulation situation and the injection of common-mode voltage in the multi-phase system and the solution of the transformation matrix increase the complexity of the method. The space vector modulation method in the literature [2] uses the α-β subspace, xy subspace virtual voltage vector and zero-axis synthetic vector, resulting in a low utilization rate of the DC bus voltage and failure to fully utilize the output capacity of the inverter. Summary of the invention

[0006] The technical problem to be solved by the present invention is to provide a spatial vector modulation method for a five-phase series-end winding permanent magnet synchronous motor, perform modulation analysis within the maximum three-dimensional modulatable domain that a five-phase six-bridge-arm series-end winding inverter can output, make full use of the output capacity of the five-phase six-bridge-arm series-end winding inverter, track the reference voltage with high accuracy under the premise of low computational burden, and scale the reference voltage vector to the adjustable boundary when the reference voltage vector exceeds the modulatable domain, provide intuitive overmodulation analysis, effectively suppress harmonic current and zero-sequence current, and improve the utilization rate of the DC bus voltage.

[0007] The present invention is achieved through the following technical solutions: A space vector modulation method for a five-phase series end winding permanent magnet synchronous motor comprises the following steps: S1: Map all phase voltages output by the five-phase six-bridge-arm series-end winding inverter from the natural coordinate system to the two-phase stationary coordinate system, and draw the voltage vector distribution according to the mapping result; S2: The fundamental wave plane and the zero axis are regarded as a three-dimensional spatial modulation domain as a whole. Based on the drawn voltage vector distribution, multiple voltage vectors containing zero-sequence components with the largest amplitude projected on the fundamental wave plane are selected as the basic voltage vectors of the modulation zero axis in the three-dimensional spatial modulation domain. Multiple voltage vectors without zero-sequence components with the largest amplitude in the fundamental wave plane and the harmonic plane are selected as the basic voltage vectors of the corresponding planes. The endpoints of the basic voltage vectors of the modulation zero axis in the three-dimensional spatial modulation domain are connected in sequence with the endpoints of the basic voltage vectors of the fundamental wave plane to form a three-dimensional maximum modulation domain of the five-phase six-bridge arm series end winding inverter, and the maximum modulation domain is divided into multiple sub-tetrahedrons; S3: in the three-dimensional spatial modulation domain, based on multiple sub-tetrahedrons, a lookup table is established to obtain the duty ratios of three adjacent basic voltage vectors of the reference voltage vector, in the two-dimensional spatial modulation domain, the sector where the reference voltage vector is located is determined, and the duty ratios of two virtual voltage vectors and four basic voltage vectors adjacent to the reference voltage vector are calculated, and it is determined whether each reference voltage vector is overmodulated. If each reference voltage vector exceeds the modulatable range, the process goes to step S4. If each reference voltage vector does not exceed the modulatable range, the process goes directly to step S5. S4: overmodulating each reference voltage vector in the three-dimensional spatial modulation domain and the two-dimensional spatial modulation domain and then proceeding to step S5; S5: For each basic voltage vector of the synthetic reference voltage vector, the switching sequence is rearranged according to the superposition theorem to obtain a symmetrical switching sequence within a switching cycle, and then the duty cycle of the upper bridge arm is recalculated. If the duty cycle of the upper bridge arm is greater than 1, a double sampling period modulation strategy is adopted for modulation, and the switching sequence is centrally symmetric and input into a five-phase six-bridge-arm series-end winding inverter to drive the five-phase six-bridge-arm series-end winding inverter to control the five-phase series-end winding permanent magnet synchronous motor. If the duty cycle of the upper bridge arm is less than or equal to 1, the obtained symmetrical switching sequence within a switching cycle is directly input into the five-phase six-bridge-arm series-end winding inverter to drive the five-phase six-bridge-arm series-end winding inverter to control the five-phase series-end winding permanent magnet synchronous motor.

[0008] Furthermore, in step S1, all phase voltages output by the five-phase six-bridge-arm series-end winding inverter are mapped from a natural coordinate system to a two-phase stationary coordinate system using the following method: S11: According to the series connection sequence of the five-phase series end winding permanent magnet synchronous motor windings, the corresponding relationship between the conduction state of each bridge arm of the five-phase six-bridge arm series end winding inverter and the phase voltage is obtained: S12: Substituting the switch state corresponding to the five-phase six-bridge-arm series-end winding inverter into the corresponding relationship between the conduction state of each bridge arm of the five-phase six-bridge-arm series-end winding inverter and the phase voltage, to obtain a set of all phase voltage values; S13: Map the phase voltages in the set from the natural coordinate system to the two-phase stationary coordinate system via the Clarke transformation matrix.

[0009] Further, in step S11, the series connection sequence of the five-phase series-end winding permanent magnet synchronous motor windings is: Mutually, Mutually, Mutually, Mutually, Phase or Mutually, Mutually, Mutually, Mutually, Mutually.

[0010] Furthermore, in step S2, the three-dimensional spatial modulation domain includes 10 basic voltage vectors with the largest amplitude in the fundamental wave plane and 16 basic voltage vectors of the modulation zero axis. The 16 basic voltage vectors of the modulation zero axis include 8 voltage vectors with zero-sequence components on the positive zero axis and 8 voltage vectors with zero-sequence components on the negative zero axis. There are 10 basic voltage vectors with the largest amplitude in the harmonic plane in the two-dimensional spatial modulation domain.

[0011] Further, in step S3, the basic voltage vector of each reference voltage vector in the three-dimensional spatial modulation domain and the two-dimensional spatial modulation domain is obtained by the following method: Three-dimensional spatial modulation domain: Substitute the endpoint coordinates of the reference voltage vector output by the PI controller into the plane equations corresponding to its sector that divide the maximum modulation domain into several sub-tetrahedrons, and judge the positional relationship between the reference voltage vector and each plane based on the positivity of the substitution result. If the result is positive, the reference voltage vector is above the corresponding plane, and if the result is negative, it means that the reference voltage vector is below the corresponding plane, thereby determining the only sub-tetrahedron where the reference voltage vector is located, and then synthesize the reference voltage vector by the three basic voltage vectors that constitute the sub-tetrahedron to obtain each reference voltage vector in the three-dimensional spatial modulation domain; Two-dimensional spatial modulation domain: One-way decoupling is achieved in the harmonic plane by synthesizing a virtual voltage vector. The single virtual voltage vector is synthesized by a large-amplitude voltage vector and a medium-amplitude voltage vector. The position of the reference voltage vector in the harmonic plane is obtained while taking into account the influence of the additional components. Then the reference voltage vector is synthesized by two adjacent virtual voltage vectors.

[0012] Furthermore, before substituting the endpoint coordinates of the reference voltage vector output by the PI controller into the plane equations of multiple sub-tetrahedrons in the maximum modulation domain, the positive zero axis direction of the fundamental wave plane and the negative zero axis direction of the fundamental wave plane are re-divided into sectors according to the selected multiple basic vectors containing zero-sequence components, so that each sub-tetrahedron is located on multiple sectors, and the planes enclosing the sub-tetrahedron form a corresponding relationship with the sector in which they are located. When determining the positional relationship between the reference voltage vector and each plane of the sub-tetrahedron, first determine the sector number corresponding to the reference voltage vector on the fundamental wave plane, and then determine the positional relationship with the plane corresponding to the sector, so as to quickly determine the unique sub-tetrahedron where the reference voltage vector is located.

[0013] Further, in step S3, the duty ratio of the basic voltage vector of the sub-tetrahedron where three adjacent reference voltage vectors are located in the three-dimensional spatial modulation domain is calculated by formula (1), and the duty ratio of the virtual voltage vector adjacent to the sector where each reference voltage vector is located in the two-dimensional spatial modulation domain is calculated by formula (2): (1): (2); in: The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, Indicates the reference voltage vector The weight on the axis, Indicates the reference voltage vector The weight on the axis, Indicates the reference voltage vector The weight on the axis, represents the first virtual vector of two adjacent virtual vectors in the sector, , represents the second virtual vector of two adjacent virtual vectors in the sector, , Represents a virtual vector The duty cycle, Represents a virtual vector The duty cycle, Represents a virtual vector About the x-axis component, Represents a virtual vector About the x-axis component, Represents a virtual vector About the y-axis component, Represents a virtual vector About the y-axis component, represents the x-axis component of the reference voltage vector, represents the y-axis component of the reference voltage vector, It represents the sum of the additional voltage components generated by the three basic voltage vectors on the x-axis. It represents the sum of the additional voltage components generated by the three basic voltage vectors on the y-axis.

[0014] Further, in step S3, it is determined whether each reference voltage vector is overmodulated according to the following method: The sum of the duty cycles of the adjacent basic voltage vectors of the sub-tetrahedron where the reference voltage vector is located in the three-dimensional spatial modulation domain and the sum of the duty cycles of the four basic voltage vectors used to synthesize the two virtual vectors of the synthesized reference voltage vector in the two-dimensional spatial modulation domain are calculated. If the sum of the duty cycles of the adjacent basic voltage vectors is greater than 1, it means that each reference voltage vector is overmodulated. If the sum of the duty cycles of the adjacent basic voltage vectors is less than or equal to 1, it means that each reference voltage vector is within the modulatable range of the five-phase six-bridge-arm series end winding inverter.

[0015] Optimally, in step S4, the minimum phase error method is used to keep the phase unchanged, and the reference voltage vector is scaled to the modulatable boundary to complete the modulation.

[0016] Furthermore, the dual sampling period modulation strategy in step S5 is: the first sampling period performs three-dimensional spatial modulation domain modulation to achieve central symmetry of the switch sequence, and the second sampling period performs two-dimensional spatial modulation domain modulation to achieve central symmetry of the switch sequence.

[0017] Beneficial effects of the invention: The present invention provides a space vector modulation method for a five-phase series-end winding permanent magnet synchronous motor. By performing modulation analysis within the maximum three-dimensional modulatable domain that can be output by the five-phase six-bridge-arm series-end winding inverter, the output capacity of the five-phase six-bridge-arm series-end winding inverter is fully utilized. The reference voltage can be tracked with high accuracy under the premise of low computational burden. When the reference voltage vector exceeds the modulatable domain, the vector is scaled to the adjustable boundary, and an intuitive overmodulation analysis is provided. Independent control of each subspace can effectively suppress harmonic current and zero-sequence current, and the maximum modulation ratio on the fundamental wave plane can reach 1, which has a high DC bus voltage utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1It is a schematic diagram of the process of the present invention.

[0019] Figure 2 It is a driving circuit diagram of a five-phase six-bridge-arm series-connected end winding inverter of the present invention.

[0020] Figure 3 This is the voltage vector distribution diagram finally drawn by the present invention.

[0021] Figure 4 It is a schematic diagram of the modulatable domain of the present invention.

[0022] Figure 5 It is a schematic diagram of the linear modulation domain of the present invention.

[0023] Figure 6 It is a schematic diagram of voltage vector selection and plane selection according to the maximum modulation domain division method of the present invention.

[0024] Figure 7 It is a schematic diagram of the re-division of the fundamental wave plane sectors of the present invention.

[0025] Figure 8 It is a schematic diagram of the switching sequence based on the superposition theorem of the present invention.

[0026] Fig. 9 This is the virtual voltage vector distribution diagram of the present invention. DETAILED DESCRIPTION

[0027] A space vector modulation method for a five-phase series end winding permanent magnet synchronous motor, the specific flow chart is as follows Figure 1 As shown, it includes the following steps: S1: Map all phase voltages output by the five-phase six-bridge-arm series-end winding inverter from the natural coordinate system to the two-phase stationary coordinate system, and draw the voltage vector distribution according to the mapping result; Specifically, the following method can be used to map all phase voltages output by the five-phase six-bridge-arm series-end winding inverter from a natural coordinate system to a two-phase stationary coordinate system: S11: According to the series connection sequence of the five-phase series end winding permanent magnet synchronous motor windings, the corresponding relationship between the conduction state of each bridge arm of the five-phase six-bridge arm series end winding inverter and the phase voltage is obtained: Specifically, the series connection sequence of the five-phase series end winding permanent magnet synchronous motor windings can be preferably Mutually, Mutually, Mutually, Mutually, Phase or Mutually, Mutually, Mutually, Mutually, Mutually.

[0028] According to the relationship between the winding series connection sequence and the DC bus voltage utilization rate, the series connection sequence of the five-phase series end winding permanent magnet synchronous motor windings adopts the above two series connection sequences, which can make the five-phase six-bridge arm series end winding inverter have the highest utilization rate of the DC bus.

[0029] The specific serial order is Mutually, Mutually, Mutually, Mutually, As an example, the five-phase six-bridge-arm series-connected end winding inverter drive circuit diagram is as follows Figure 2 As shown in the figure represents the current flowing through the first bridge arm of the five-phase six-bridge-arm series-connected end winding inverter, represents the current flowing through the second bridge arm of the five-phase six-bridge-arm series-connected end winding inverter, represents the current flowing through the third bridge arm of the five-phase six-bridge-arm series-connected end winding inverter, represents the current flowing through the fourth bridge arm of the five-phase six-bridge-arm series-connected end winding inverter, represents the current flowing through the fifth bridge arm of the five-phase six-bridge-arm series-connected end winding inverter, represents the current flowing through the sixth bridge arm of the five-phase six-bridge-arm series-end winding inverter, is the zero sequence current, Indicates the natural coordinate system Phase current of phase winding, Indicates the natural coordinate system Phase current of phase winding, Indicates the natural coordinate system Phase current of phase winding, Indicates the natural coordinate system Phase current of phase winding, In the natural coordinate system The phase current of the phase winding, based on the series connection sequence of the windings, the conduction state of different bridge arms can output different phase voltages. The relationship between the phase voltage of each winding and the conduction state of the bridge arm is expressed as formula (3): (3); in: Indicates the natural coordinate system Phase voltage of the phase winding, Indicates the natural coordinate system Phase voltage of the phase winding, Indicates the natural coordinate system Phase voltage of the phase winding, Indicates the natural coordinate system Phase voltage of the phase winding, Indicates the natural coordinate system Phase voltage of the phase winding, Indicates the DC bus voltage, Indicates the conduction state of the first bridge arm of the five-phase six-bridge-arm series-end winding inverter, Indicates the conduction state of the second bridge arm of the five-phase six-bridge-arm series-end winding inverter, Indicates the conduction state of the third bridge arm of the five-phase six-bridge-arm series-end winding inverter, Indicates the conduction state of the fourth bridge arm of the five-phase six-bridge-arm series-end winding inverter, Indicates the conduction state of the fifth bridge arm of the five-phase six-bridge-arm series-end winding inverter, Indicates the conduction state of the sixth bridge arm of the five-phase six-bridge-arm series-end winding inverter. S i ( i =1, 2…6) = 1 means the five-phase six-bridge-arm series-connected end winding inverter The upper arm of the bridge is turned on and the lower arm is turned off. S i ( i =1, 2…6) = 0 means the five-phase six-bridge-arm series-connected end winding inverter The lower bridge arm of the bridge arm is turned on and the upper bridge arm is turned off.

[0030] S12: Substituting the switch state corresponding to the five-phase six-bridge-arm series-end winding inverter into the corresponding relationship between the conduction state of each bridge arm of the five-phase six-bridge-arm series-end winding inverter and the phase voltage, to obtain a set of all phase voltage values; Six-bridge-arm five-phase six-bridge-arm series-end winding inverter corresponding There are several switching states. Substituting each switching state into equation (3) can obtain a set of phase voltage values.

[0031] S13: Map the phase voltages in the set from the natural coordinate system to the two-phase stationary coordinate system via the Clarke transformation matrix.

[0032] The Clarke transformation matrix is ​​formula (4): (4) in: represents the Clarke transformation matrix, Represents the phase difference between the windings, which is 0.4π.

[0033] By mapping the phase voltages in the set from the natural coordinate system to the two-phase stationary coordinate system through the Clarke transformation matrix, the calculation results shown in Table 1 can be obtained: Table 1

[0034] In Table 1, the basic voltage vectors are divided into two categories: those with zero-sequence components and those without zero-sequence components. The voltage vectors without zero-sequence components on the α-β plane can be divided into three groups of voltage vector sets with different amplitudes: a large vector set with the largest amplitude, a medium vector set with a medium amplitude, and a small vector set with the smallest amplitude. Similarly, the xy plane is also divided into three groups of vector sets. The amplitude of the voltage vector with zero-sequence components is 0.2 , unevenly distributed in the positive and negative zero axis directions.

[0035] Here, the α-β plane is the fundamental wave plane, and the xy plane is the harmonic plane.

[0036] The final voltage vector distribution diagram is as follows: Figure 3 As shown; S2: The fundamental wave plane and the zero axis are regarded as a three-dimensional spatial modulation domain as a whole. Based on the drawn voltage vector distribution, multiple voltage vectors containing zero-sequence components with the largest amplitude projected on the fundamental wave plane are selected as the basic voltage vectors of the modulation zero axis in the three-dimensional spatial modulation domain. Multiple voltage vectors without zero-sequence components with the largest amplitude in the fundamental wave plane and the harmonic plane are selected as the basic voltage vectors of the corresponding planes. The endpoints of the basic voltage vectors of the modulation zero axis in the three-dimensional spatial modulation domain are connected in sequence with the endpoints of the basic voltage vectors of the fundamental wave plane to form a three-dimensional maximum modulation domain of the five-phase six-bridge arm series end winding inverter, and the maximum modulation domain is divided into multiple sub-tetrahedrons; Specifically, the three-dimensional spatial modulation domain includes 10 basic voltage vectors with the largest amplitude in the fundamental wave plane and 16 basic voltage vectors of the modulation zero axis. The 16 basic voltage vectors of the modulation zero axis include 8 positive zero axis voltage vectors containing zero-sequence components and 8 negative zero axis voltage vectors containing zero-sequence components. There are 10 basic voltage vectors with the largest amplitude in the harmonic plane in the two-dimensional spatial modulation domain.

[0037] The maximum modulation domain of the five-phase six-bridge-arm series-end winding inverter is a 22-hedron, and the linear modulation domain is the corresponding inscribed frustum with a radius of 0.7708. , the bottom radius is 1.1708 , the modulatable domain is Figure 4 As shown, the linear modulation domain is shown in Figure 5.

[0038] The modulation ratio on the fundamental wave plane and the zero axis is given by equation (5): (5); In the formula, represents the modulation ratio of the fundamental wave, represents the modulation ratio on the zero axis, Represents the projection component of the reference voltage on the fundamental wave plane, is the projection component of the reference voltage on the zero axis.

[0039] Due to the constraints between each other, and When both are not zero, the maximum values ​​of the two modulation ratios cannot reach 1 at the same time. From equation (4) and the linear modulation domain, we can get The maximum value and The relationship is expressed as formula (6): (6); In the formula, is the maximum value of the modulation ratio on the zero axis.

[0040] In order to accurately determine the position of the reference voltage vector in the maximum modulation domain of the three-dimensional space and the voltage vector synthesized from it, the maximum modulation domain of the three-dimensional space is considered to be cut and subdivided by a plane into several sub-tetrahedrons.

[0041] Since three non-collinear points can determine a plane, The plane equation is ,in As its normal vector, substituting the other two points into the equation, the plane equation determined by the three points can be derived as equation (7): (7); In the formula, is the plane equation, , and are the coordinates of any three points, It means to find the determinant.

[0042] According to the above plane equation solution process, the origin coordinates and the endpoint coordinates of the two voltage vectors are used as the three point coordinates for solving the plane equation. Substituting the three coordinates into equation (7) can solve the corresponding plane equation. By analyzing the maximum modulation domain of three-dimensional space, the maximum modulation domain division method voltage vector selection and plane selection schematic diagram are shown in the figure. Figure 6 As shown in the figure, 22 planes are selected to cut and divide the modulation domain, and the maximum modulation domain can be subdivided into 48 sub-tetrahedrons, among which Indicates plane, is an auxiliary plane, which contains 8 auxiliary voltage vectors in addition to the 26 basic voltage vectors, used to assist in the division. Each tetrahedron is composed of 3 adjacent basic voltage vectors among the 26 voltage vectors. The above division is the division of the maximum modulation domain. In the figure, each plane is simplified by a line segment, and each plane contains 6 coplanar basic voltage vectors. For example, the plane The voltage vectors on the same plane are , , , , and ,in and The endpoint coordinates are (0.8472 , 0.6155 , 0.2 )、(-0.3236 , 0.996 , 0.2 ), substituting into equation (7) we get the plane equation: , the same is true for other planes, and the final results are shown in Table 2: Table 2

[0043] S3: in the three-dimensional spatial modulation domain, based on multiple sub-tetrahedrons, a lookup table is established to obtain the duty ratios of three adjacent basic voltage vectors of the reference voltage vector, in the two-dimensional spatial modulation domain, the sector where the reference voltage vector is located is determined, and the duty ratios of two virtual voltage vectors and four basic voltage vectors adjacent to the reference voltage vector are calculated, and it is determined whether each reference voltage vector is overmodulated. If each reference voltage vector exceeds the modulatable range, the process goes to step S4. If each reference voltage vector does not exceed the modulatable range, the process goes directly to step S5. Specifically, the basic voltage vector of each reference voltage vector in the three-dimensional spatial modulation domain and the two-dimensional spatial modulation domain can be obtained by the following method: Three-dimensional spatial modulation domain: Substitute the endpoint coordinates of the reference voltage vector output by the PI controller into the plane equations corresponding to its sector that divide the maximum modulation domain into several sub-tetrahedrons, and judge the positional relationship between the reference voltage vector and each plane based on the positivity of the substitution result. If the result is positive, the reference voltage vector is above the corresponding plane, and if the result is negative, it means that the reference voltage vector is below the corresponding plane, thereby determining the only sub-tetrahedron where the reference voltage vector is located, and then synthesize the reference voltage vector by the three basic voltage vectors that constitute the sub-tetrahedron to obtain each reference voltage vector in the three-dimensional spatial modulation domain; Two-dimensional spatial modulation domain: One-way decoupling is achieved in the harmonic plane by synthesizing a virtual voltage vector. The single virtual voltage vector is synthesized by a large-amplitude voltage vector and a medium-amplitude voltage vector. The position of the reference voltage vector in the harmonic plane is obtained while taking into account the influence of the additional components. Then the reference voltage vector is synthesized by two adjacent virtual voltage vectors.

[0044] In order to reduce the amount of calculation for substituting into 22 planes, before substituting the endpoint coordinates of the reference voltage vector output by the PI controller into the plane equations of multiple sub-tetrahedrons dividing the maximum modulation domain, the positive zero axis direction of the fundamental wave plane and the negative zero axis direction of the fundamental wave plane can be re-divided into sectors according to the selected multiple basic vectors containing zero-sequence components, so that each sub-tetrahedron is located on multiple sectors, and the planes enclosing the sub-tetrahedron form a corresponding relationship with the sector in which they are located. When determining the positional relationship between the reference voltage vector and each plane of the sub-tetrahedron, first determine the sector number corresponding to the reference voltage vector on the fundamental wave plane, and then determine the positional relationship with the plane corresponding to the sector, so as to quickly determine the unique sub-tetrahedron where the reference voltage vector is located and the corresponding three adjacent basic voltage vectors.

[0045] In two-dimensional spatial modulation, unidirectional decoupling is achieved in the harmonic plane by synthesizing a virtual voltage vector. The single virtual voltage vector is synthesized by a large-amplitude voltage vector and a medium-amplitude voltage vector. The position of the reference voltage vector in the harmonic plane is obtained while taking into account the influence of the additional components. Then the reference voltage vector is synthesized by two adjacent virtual voltage vectors, thereby avoiding the coupling influence of the modulation result of the two-dimensional spatial modulation domain on the three-dimensional spatial modulation domain.

[0046] Specifically, the virtual voltage vector distribution diagram is as follows: Fig. 9 shown.

[0047] Specifically, the calculation formula for obtaining the reference voltage vector position in the harmonic plane is formula (8): (8); Where: is the angle between the reference voltage vector and the x-axis, represents the x-axis component of the reference voltage vector, represents the y-axis component of the reference voltage vector, It represents the sum of the additional voltage components generated by the three basic voltage vectors on the x-axis. It represents the sum of the additional voltage components generated by the three basic voltage vectors on the y-axis. Indicates The additional voltage component generated by the basic voltage vector on the x-axis is No. The additional voltage component generated by the basic voltage vector on the x-axis is Indicates The additional voltage component generated by the basic voltage vector on the x-axis is Indicates The additional voltage component generated by the basic voltage vector on the y-axis is No. The additional voltage component generated by the basic voltage vector on the y-axis is Indicates The additional voltage component generated by the basic voltage vector on the y-axis is The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located duty cycle.

[0048] The formula (8) gives The position of the reference voltage vector in the harmonic plane can be determined, and then the reference voltage vector is composed of two virtual vectors adjacent to the sector where it is located. , To synthesize, There are two basic voltage vectors , synthesis, There are two basic voltage vectors , Synthesis, where Indicates the first A large vector, is the first voltage vector in the basic voltage vector Among them, the vector Indicates the first A large vector, is the first voltage vector in the basic voltage vector The vector.

[0049] Specifically, the duty cycle of the basic voltage vector of the sub-tetrahedron where three adjacent reference voltage vectors are located in the three-dimensional spatial modulation domain can be calculated by formula (1), and the duty cycle of the virtual voltage vector adjacent to the sector where each reference voltage vector is located in the two-dimensional spatial modulation domain can be calculated by formula (2): (1): (2); in: The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, Indicates the reference voltage vector The weight on the axis, Indicates the reference voltage vector The weight on the axis, Indicates the reference voltage vector The weight on the axis, represents the first virtual vector of two adjacent virtual vectors in the sector, , represents the second virtual vector of two adjacent virtual vectors in the sector, , Represents a virtual vector The duty cycle, Represents a virtual vector The duty cycle, Represents a virtual vector About the x-axis component, Represents a virtual vector About the x-axis component, Represents a virtual vector About the y-axis component, Represents a virtual vector About the y-axis component, represents the x-axis component of the reference voltage vector, represents the y-axis component of the reference voltage vector, It represents the sum of the additional voltage components generated by the three basic voltage vectors on the x-axis. It represents the sum of the additional voltage components generated by the three basic voltage vectors on the y-axis.

[0050] Specifically, the schematic diagram of re-dividing the fundamental wave plane sectors is as follows: Figure 7 As shown in the figure For the Each sub-tetrahedron is located on multiple sectors, and the planes used to enclose the sub-tetrahedron are considered to have a corresponding relationship with the sector in which it is located. The relationship between the planes corresponding to the sectors in the positive zero axis direction is shown in Table 3: Table 3

[0051] When determining the positional relationship between the reference voltage vector and each plane of the sub-tetrahedron, first determine the sector number corresponding to the reference voltage vector on the fundamental wave plane, and then determine the positional relationship with the plane corresponding to the sector, so as to quickly determine the unique sub-tetrahedron where the reference voltage vector is located. This avoids the large amount of calculation caused by 22 substitutions each time. For example, with respect to the positive zero axis direction There are 5 corresponding planes, namely , , , and , The synthetic reference voltage vector Components on the axis The positive and negative relationship can be judged. In this way, the tetrahedron where the reference voltage vector is located can be determined by judging the position relationship of the four planes. Similarly, other sectors can be judged after comparison with only 7 calculations at most.

[0052] The discriminant of three adjacent basic voltage vectors is determined by the sector number and the positional relationship with respect to the corresponding plane as shown in equation (9): (9); in: represents the discriminant, Indicates the first plane, Indicates the first The reference voltage vector is located at When above, ,lie in When below .

[0053] according to Figure 6 By analyzing the corresponding relationship between the reference voltage vector and the plane, a lookup table as shown in Table 4 can be designed: Table 4

[0054] In Table 4, T i (i=1, 2…24) is the number of each sub-tetrahedron, and only the positive zero axis direction is shown. Similarly, the negative zero axis also has 24 sub-tetrahedrons. The contents of the lookup table include the number of each tetrahedron, the numbers of the three adjacent basic voltage vectors that constitute it, and the specific value of the discriminant corresponding to each tetrahedron.

[0055] Specifically, the reference voltage vector The sign of the component on the axis and the reference voltage vector The components on the axis, the reference voltage vector The quantitative relationship between the components on the axis is calculated by the reference voltage vector in the fundamental wave plane and Axis angle , and determine the specific sector where it is located; then the reference voltage vector is The components on the axis, the reference voltage vector The components on the axis, the reference voltage vector The modulus of the component on the axis is brought into the plane group corresponding to the sector where the reference voltage vector is located, and the discriminant is calculated , and then according to the discriminant The specific sub-tetrahedron where the reference voltage vector is located and three adjacent basic voltage vectors are found by using an offline lookup table, and their respective duty cycles are calculated, and the remaining duty cycles are allocated to the zero voltage vector.

[0056] By looking up the discriminant obtained by equation (9), the tetrahedron where the reference voltage vector is located and the three adjacent basic voltage vectors can be quickly and accurately determined.

[0057] For ease of analysis, we can agree on the vector numbering , the remaining duty cycle is allocated to the zero voltage vector.

[0058] Specifically, whether each reference voltage vector is overmodulated may be determined according to the following method: The sum of the duty cycles of the adjacent basic voltage vectors of the sub-tetrahedron where the reference voltage vector is located in the three-dimensional spatial modulation domain and the sum of the duty cycles of the four basic voltage vectors used to synthesize the two virtual vectors of the synthesized reference voltage vector in the two-dimensional spatial modulation domain are calculated. If the sum of the duty cycles of the adjacent basic voltage vectors is greater than 1, it means that each reference voltage vector is overmodulated. If the sum of the duty cycles of the adjacent basic voltage vectors is less than or equal to 1, it means that each reference voltage vector is within the modulatable range of the five-phase six-bridge-arm series end winding inverter.

[0059] S4: overmodulating each reference voltage vector in the three-dimensional spatial modulation domain and the two-dimensional spatial modulation domain and then proceeding to step S5; Specifically, the minimum phase error method can be used to keep the phase unchanged, scale the reference voltage vector to the modulatable boundary, and complete the modulation.

[0060] The duty cycle adjustment formula after modulation is as follows: (9); in: represents the duty cycle of the basic voltage vector before modulation, Represents the duty cycle of the basic voltage vector after overmodulation.

[0061] S5: For each basic voltage vector of the synthetic reference voltage vector, the switching sequence is rearranged according to the superposition theorem to obtain a symmetrical switching sequence within a switching cycle, and then the duty cycle of the upper bridge arm is recalculated. If the duty cycle of the upper bridge arm is greater than 1, a double sampling period modulation strategy is adopted for modulation, and the switching sequence is centrally symmetric and input into a five-phase six-bridge-arm series-end winding inverter to drive the five-phase six-bridge-arm series-end winding inverter to control the five-phase series-end winding permanent magnet synchronous motor. If the duty cycle of the upper bridge arm is less than or equal to 1, the obtained symmetrical switching sequence within a switching cycle is directly input into the five-phase six-bridge-arm series-end winding inverter to drive the five-phase six-bridge-arm series-end winding inverter to control the five-phase series-end winding permanent magnet synchronous motor.

[0062] Specifically, the dual sampling period modulation strategy is: the first sampling period performs three-dimensional spatial modulation domain modulation to achieve the central symmetry of the switch sequence, and the second sampling period performs two-dimensional spatial modulation domain modulation to achieve the central symmetry of the switch sequence.

[0063] After overmodulation, 7 basic voltage vectors and their respective duty cycles can be obtained. The original modulation strategy uses a seven-segment algorithm in a single sampling cycle. Since there are a large number of voltage vectors, the multi-phase switch state changes each time the switch is switched, which is not only difficult to implement, but also will lead to large switching losses and unstable switching frequency. Therefore, according to the superposition theorem, the switching sequence is rearranged into a symmetrical switching sequence within a switching cycle, and then the duty cycle of each upper bridge arm can be expressed as formula (10): (10); in: Indicates The duty cycle of the upper bridge arm, The voltage vector number finally selected is The upper arm conduction state corresponding to the basic voltage vector or zero voltage vector is The voltage vector number finally selected is The duty cycle of the basic voltage vector or zero voltage vector, The voltage vector number finally selected is The basic voltage vector or zero voltage vector.

[0064] You can choose and As zero voltage vectors, their duty cycles each account for half of the remaining duty cycle.

[0065] For example: Assume that three adjacent basic voltage vectors are selected , , And the synthetic virtual vector , , , , the switching sequence diagram based on the superposition theorem is as follows Figure 8 As shown, Figure 8 middle, is the switching cycle. However, there is a special case where the bridge arm conduction time is much longer than one switching cycle, that is, , mainly because part of the DC bus voltage is used when modulating the two-dimensional modulation domain. The equivalent three-dimensional linear modulation range is smaller than the theoretical analysis. A single sampling period is not enough to control the three subspaces at the same time, and the phase current is distorted. In the case of severe distortion, a dual sampling period modulation strategy is adopted, and the switching sequence is centrally symmetric. The obtained switching sequence is input into the inverter, thereby driving the inverter to realize the control of the five-phase permanent magnet synchronous motor, which can keep the phase current with good current performance and no current distortion.

[0066] In summary, the present invention provides a spatial vector modulation method for a five-phase series-end winding permanent magnet synchronous motor. By performing modulation analysis within the maximum three-dimensional modulatable domain that the five-phase six-bridge-arm series-end winding inverter can output, the output capacity of the five-phase six-bridge-arm series-end winding inverter is fully utilized. The reference voltage can be tracked with high precision under the premise of low computational burden. When the reference voltage vector exceeds the modulatable domain, the vector is scaled to the adjustable boundary, and an intuitive overmodulation analysis is provided. The independent control of each subspace can effectively suppress harmonic current and zero-sequence current, and the maximum modulation ratio on the fundamental wave plane can reach 1, which has a high DC bus voltage utilization rate.

[0067] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A space vector modulation method for a five-phase series end winding permanent magnet synchronous motor, characterized in that: The steps include: S1: Map all phase voltages output by the five-phase six-bridge-arm series-end winding inverter from the natural coordinate system to the two-phase stationary coordinate system, and draw the voltage vector distribution according to the mapping result; S2: The fundamental wave plane and the zero axis are regarded as a three-dimensional spatial modulation domain as a whole. Based on the drawn voltage vector distribution, multiple voltage vectors containing zero-sequence components with the largest amplitude projected on the fundamental wave plane are selected as the basic voltage vectors of the modulation zero axis in the three-dimensional spatial modulation domain. Multiple voltage vectors without zero-sequence components with the largest amplitude in the fundamental wave plane and the harmonic plane are selected as the basic voltage vectors of the corresponding planes. The endpoints of the basic voltage vectors of the modulation zero axis in the three-dimensional spatial modulation domain are connected in sequence with the endpoints of the basic voltage vectors of the fundamental wave plane to form a three-dimensional maximum modulation domain of the five-phase six-bridge arm series end winding inverter, and the maximum modulation domain is divided into multiple sub-tetrahedrons; S3: in the three-dimensional spatial modulation domain, based on multiple sub-tetrahedrons, a lookup table is established to obtain the duty ratios of three adjacent basic voltage vectors of the reference voltage vector, in the two-dimensional spatial modulation domain, the sector where the reference voltage vector is located is determined, and the duty ratios of two virtual voltage vectors and four basic voltage vectors adjacent to the reference voltage vector are calculated, and it is determined whether each reference voltage vector is overmodulated. If each reference voltage vector exceeds the modulatable range, the process goes to step S4. If each reference voltage vector does not exceed the modulatable range, the process goes directly to step S5. S4: overmodulating each reference voltage vector in the three-dimensional spatial modulation domain and the two-dimensional spatial modulation domain and then proceeding to step S5; S5: For each basic voltage vector of the synthetic reference voltage vector, the switching sequence is rearranged according to the superposition theorem to obtain a symmetrical switching sequence within a switching cycle, and then the duty cycle of the upper bridge arm is recalculated. If the duty cycle of the upper bridge arm is greater than 1, a double sampling period modulation strategy is adopted for modulation, and the switching sequence is centrally symmetric and input into a five-phase six-bridge-arm series-end winding inverter to drive the five-phase six-bridge-arm series-end winding inverter to control the five-phase series-end winding permanent magnet synchronous motor. If the duty cycle of the upper bridge arm is less than or equal to 1, the obtained symmetrical switching sequence within a switching cycle is directly input into the five-phase six-bridge-arm series-end winding inverter to drive the five-phase six-bridge-arm series-end winding inverter to control the five-phase series-end winding permanent magnet synchronous motor.

2. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 1, characterized in that: In step S1, all phase voltages output by the five-phase six-bridge-arm series-end winding inverter are mapped from a natural coordinate system to a two-phase stationary coordinate system using the following method: S11: According to the series connection sequence of the five-phase series end winding permanent magnet synchronous motor windings, the corresponding relationship between the conduction state of each bridge arm of the five-phase six-bridge arm series end winding inverter and the phase voltage is obtained: S12: Substituting the switch state corresponding to the five-phase six-bridge-arm series-end winding inverter into the corresponding relationship between the conduction state of each bridge arm of the five-phase six-bridge-arm series-end winding inverter and the phase voltage, to obtain a set of all phase voltage values; S13: Map the phase voltages in the set from the natural coordinate system to the two-phase stationary coordinate system via the Clarke transformation matrix.

3. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 2, characterized in that: The series connection sequence of the five-phase series-end winding permanent magnet synchronous motor windings in step S11 is: Mutually, Mutually, Mutually, Mutually, Phase or Mutually, Mutually, Mutually, Mutually, Mutually.

4. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 1, characterized in that: In step S2, the three-dimensional spatial modulation domain includes 10 basic voltage vectors with the largest amplitude in the fundamental wave plane and 16 basic voltage vectors of the modulation zero axis. The 16 basic voltage vectors of the modulation zero axis include 8 positive zero axis voltage vectors containing zero-sequence components and 8 negative zero axis voltage vectors containing zero-sequence components. There are 10 basic voltage vectors with the largest amplitude in the harmonic plane in the two-dimensional spatial modulation domain.

5. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 1, characterized in that: In step S3, the basic voltage vector of each reference voltage vector in the three-dimensional spatial modulation domain and the two-dimensional spatial modulation domain is obtained by the following method: Three-dimensional spatial modulation domain: Substitute the endpoint coordinates of the reference voltage vector output by the PI controller into the plane equations corresponding to its sector that divide the maximum modulation domain into several sub-tetrahedrons, and judge the positional relationship between the reference voltage vector and each plane based on the positivity of the substitution result. If the result is positive, the reference voltage vector is above the corresponding plane, and if the result is negative, it means that the reference voltage vector is below the corresponding plane, thereby determining the only sub-tetrahedron where the reference voltage vector is located, and then synthesize the reference voltage vector by the three basic voltage vectors that constitute the sub-tetrahedron to obtain each reference voltage vector in the three-dimensional spatial modulation domain; Two-dimensional spatial modulation domain: One-way decoupling is achieved in the harmonic plane by synthesizing a virtual voltage vector. The single virtual voltage vector is synthesized by a large-amplitude voltage vector and a medium-amplitude voltage vector. The position of the reference voltage vector in the harmonic plane is obtained while taking into account the influence of the additional components. Then the reference voltage vector is synthesized by two adjacent virtual voltage vectors.

6. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 5, characterized in that: Before substituting the endpoint coordinates of the reference voltage vector output by the PI controller into the plane equations of multiple sub-tetrahedrons in the maximum modulation domain, the positive zero axis direction of the fundamental wave plane and the negative zero axis direction of the fundamental wave plane are re-divided into sectors according to the selected multiple basic vectors containing zero-sequence components, so that each sub-tetrahedron is located on multiple sectors, and the planes enclosing the sub-tetrahedron form a corresponding relationship with the sector in which they are located. When determining the positional relationship between the reference voltage vector and each plane of the sub-tetrahedron, first determine the sector number corresponding to the reference voltage vector on the fundamental wave plane, and then determine the positional relationship with the plane corresponding to the sector, so as to quickly determine the unique sub-tetrahedron where the reference voltage vector is located.

7. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 4, characterized in that: In step S3, the duty ratio of the basic voltage vector of the sub-tetrahedron where three adjacent reference voltage vectors are located in the three-dimensional spatial modulation domain is calculated by formula (1), and the duty ratio of the virtual voltage vector adjacent to the sector where each reference voltage vector is located in the two-dimensional spatial modulation domain is calculated by formula (2): （1）： （2）； in: The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located The duty cycle, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, The basic voltage vector in the basic voltage vector adjacent to the sub-tetrahedron where the synthetic reference voltage vector is located exist The weight on the axis, Indicates the reference voltage vector The weight on the axis, Indicates the reference voltage vector The weight on the axis, Indicates the reference voltage vector The weight on the axis, represents the first virtual vector of two adjacent virtual vectors in the sector, , represents the second virtual vector of two adjacent virtual vectors in the sector, , Represents a virtual vector The duty cycle, Represents a virtual vector The duty cycle, Represents a virtual vector About the x-axis component, Represents a virtual vector About the x-axis component, Represents a virtual vector About the y-axis component, Represents a virtual vector About the y-axis component, represents the x-axis component of the reference voltage vector, represents the y-axis component of the reference voltage vector, It represents the sum of the additional voltage components generated by the three basic voltage vectors on the x-axis. It represents the sum of the additional voltage components generated by the three basic voltage vectors on the y-axis.

8. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 1, characterized in that: In step S3, it is determined whether each reference voltage vector is overmodulated according to the following method: The sum of the duty cycles of the adjacent basic voltage vectors of the sub-tetrahedron where the reference voltage vector is located in the three-dimensional spatial modulation domain and the sum of the duty cycles of the four basic voltage vectors used to synthesize the two virtual vectors of the synthesized reference voltage vector in the two-dimensional spatial modulation domain are calculated. If the sum of the duty cycles of the adjacent basic voltage vectors is greater than 1, it means that each reference voltage vector is overmodulated. If the sum of the duty cycles of the adjacent basic voltage vectors is less than or equal to 1, it means that each reference voltage vector is within the modulatable range of the five-phase six-bridge-arm series end winding inverter.

9. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 1, characterized in that: In step S4, the minimum phase error method is used to keep the phase unchanged, and the reference voltage vector is scaled to the modulatable boundary to complete the modulation.

10. The space vector modulation method of a five-phase series end winding permanent magnet synchronous motor according to claim 1, characterized in that: The dual sampling period modulation strategy in step S5 is: the first sampling period performs three-dimensional spatial modulation domain modulation to achieve the central symmetry of the switch sequence, and the second sampling period performs two-dimensional spatial modulation domain modulation to achieve the central symmetry of the switch sequence.

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