Method for calculating no-load performance of interior permanent magnet motor

Abstract

The application discloses a calculation method of no-load performance of an interior permanent magnet motor, which comprises the following steps: obtaining motor parameters of the permanent magnet motor, wherein the motor parameters comprise a rotor initial position; calculating the radian range of a magnetic pole area and a magnetic bridge area of the rotor based on the rotor initial position; and respectively calculating the radian range of a pole slot area and a pole tooth area, wherein the pole slot area is a circumferential coincident area of the magnetic pole area and a stator slot area along a radial extension direction of the rotor, and the pole tooth area is a circumferential coincident area of the magnetic pole area and a stator tooth area along the radial extension direction of the rotor; calculating excitation magnetic flux, permanent magnet magnetic resistance, pole slot area magnetic resistance, pole tooth area magnetic resistance, magnetic barrier leakage magnetic resistance and magnetic bridge area magnetic resistance in a first pole range of the permanent magnet motor based on a lumped parameter method; and calculating air gap magnetic flux density distribution of the pole slot area, the pole tooth area and the magnetic bridge area based on a magnetic circuit method. Through the above method, the calculation efficiency of solving the air gap magnetic flux density distribution of each area is improved under the premise of ensuring the accuracy, and the complexity of designing the permanent magnet motor is simplified.

Description

Technical Field

[0001] This application relates to the field of electromagnetic field analysis of electric motors, and in particular to a method for calculating the no-load performance of an embedded permanent magnet motor. Background Technology

[0002] An embedded permanent magnet motor is a permanent magnet synchronous motor in which permanent magnets are embedded inside the rotor. In the design of an embedded permanent magnet motor, the unloaded air gap magnetic field is the core carrier of its electromagnetic performance. Its distribution characteristics (such as harmonic content) directly affect key performance indicators such as torque density and efficiency. The distribution of the air gap magnetic flux density can describe the specific numerical distribution of this magnetic field in the air gap, providing data support for the design of embedded permanent magnet motors.

[0003] If the air gap magnetic flux density distribution of an embedded permanent magnet motor is calculated using finite element simulation, on the one hand, it is necessary to model the embedded permanent magnet motor, set boundary conditions, and mesh the established model. The calculation process is complex and slow. On the other hand, if any step in the above process is flawed, there is a risk of non-convergence, which will require re-simulation and reduce the overall efficiency. If the magnetic circuit method is used for calculation, the calculation accuracy is low.

[0004] There is an urgent need for a method to calculate the no-load performance of embedded permanent magnet motors that can improve the computational efficiency of solving the air gap magnetic flux density distribution in each region while ensuring accuracy, and simplify the design of embedded permanent magnet motors. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the purpose of this application is to provide a method for calculating the no-load performance of an embedded permanent magnet motor, which can improve the calculation efficiency of solving the air gap magnetic flux density distribution in each region while ensuring accuracy, and simplify the complexity of designing permanent magnet motors.

[0006] This application provides a method for calculating the no-load performance of an embedded permanent magnet motor, which includes obtaining the motor parameters of the permanent magnet motor, including the initial position of the rotor; calculating the arc range of the magnetic pole region and magnetic bridge region of the rotor based on the initial position of the rotor; and calculating the arc range of the pole slot region and pole tooth region respectively, where the pole slot region is the circumferentially overlapping area of ​​the magnetic pole region and the stator slot region along the radial extension direction of the rotor, and the pole tooth region is the circumferentially overlapping area of ​​the magnetic pole region and the stator tooth region along the radial extension direction of the rotor; based on The lumped parameter method is used to calculate the excitation flux, permanent magnet reluctance, pole slot region reluctance, pole tooth region reluctance, magnetic barrier leakage reluctance, and magnetic bridge region reluctance within the first pole range of the permanent magnet motor. The magnetic barrier leakage reluctance is the magnetic barrier reluctance. Based on the magnetic circuit method, the arc range of the rotor's magnetic pole region and magnetic bridge region, the arc range of the pole slot region and pole tooth region, the excitation flux, magnetic bridge region reluctance, permanent magnet reluctance, pole slot region reluctance, pole tooth region reluctance, and magnetic barrier leakage reluctance, the air gap magnetic flux distribution of the pole slot region, pole tooth region, and magnetic bridge region is calculated.

[0007] In some implementations, the calculation method also includes determining the relative permeability of the material in the magnetic bridge region based on the air gap magnetic flux density distribution in the magnetic bridge region and the BH curve of the iron core; updating the relative permeability of the material in the magnetic bridge region based on a preset error convergence value; calculating the updated magnetic reluctance of the magnetic bridge region based on the updated relative permeability of the material in the magnetic bridge region, and calculating the updated air gap magnetic flux density distribution in the magnetic bridge region.

[0008] In some implementations, motor parameters include the number of poles and the number of slots; the calculation method also includes calculating the minimum number of symmetrical units, the minimum number of slots, and the minimum number of poles of the permanent magnet motor based on the greatest common divisor of the number of poles and slots.

[0009] In some implementations, the calculation method includes: when the minimum unit pole number is equal to 1, outputting all air gap magnetic flux density distributions; when the minimum unit pole number is greater than 1, the permanent magnet motor includes the nth pole adjacent to the (n-1)th pole, where n is a positive integer greater than 1 and equal to the minimum unit pole number; the calculation method includes, when the minimum unit pole number is greater than 1, calculating the air gap magnetic flux density distribution sets for the pole slot region, pole tooth region, and magnetic bridge region within the range of the second pole to the nth pole of the permanent magnet motor, respectively; based on each air gap magnetic flux density distribution in the air gap magnetic flux density distribution set and the air gap magnetic flux density distribution within the range of the first pole... For all air gap magnetic flux density distributions, determine the air gap magnetic flux density distribution curves within the range of the first to the nth pole of the permanent magnet motor. Based on the air gap magnetic flux density distribution curves, define the area enclosed by the horizontal axis and the air gap magnetic flux density distribution curves with a vertical axis greater than 0 as the first area, and define the area enclosed by the horizontal axis and the air gap magnetic flux density distribution curves with a vertical axis less than 0 as the second area. Determine the bias of the air gap magnetic flux density distribution curves based on the difference between the first and second areas. Based on the bias, update the air gap magnetic flux density distribution curves within the range of the first to the nth pole of the permanent magnet motor.

[0010] In some implementations, the magnetic pole region is the area through which the main magnetic flux of the permanent magnet passes, and the magnetic bridge region is the area covered by the magnetic isolation bridge.

[0011] In some implementations, the motor parameters include the effective axial length of the motor, the outer radius of the rotor, the air gap length, the thickness of the magnetic barrier, the length of the magnetic barrier, the thickness of the magnetic isolation bridge, and the length of the magnetic isolation bridge; the magnetic reluctance of the pole slot region within the first pole range of the permanent magnet motor is calculated, including the magnetic reluctance of the pole slot region based on the vacuum permeability, the effective axial length of the motor, the outer radius of the rotor, the arc range of the stator slot region, and the air gap length.

[0012] The magnetic reluctance of the pole tooth region within the first pole range of the permanent magnet motor is calculated by the second product of the difference between the maximum and minimum values ​​of the vacuum permeability, rotor outer radius, effective axial length of the motor, and the arc range of the pole tooth region, and the magnetic reluctance of the pole tooth region is calculated based on the quotient of the air gap length and the second product.

[0013] The leakage magnetic resistance of the magnetic barrier within the first pole range of the permanent magnet motor is calculated by a third product based on the vacuum permeability, the thickness of the magnetic barrier, and the effective axial length of the motor, and the leakage magnetic resistance of the magnetic barrier is calculated based on the quotient of the length of the magnetic barrier and the third product.

[0014] The magnetic reluctance of the magnetic bridge region within the first pole range of the permanent magnet motor is calculated by a fourth product of the vacuum permeability, the relative permeability of the magnetic bridge material, the thickness of the magnetic bridge, and the effective axial length of the motor. The magnetic reluctance of the magnetic bridge region is then calculated based on the quotient of the length of the magnetic bridge and the fourth product.

[0015] In some implementations, the motor parameters include permanent magnet width, permanent magnet remanence, permanent magnet thickness, and relative permeability of the permanent magnet;

[0016] Calculate the excitation flux within the first pole range of the permanent magnet motor, including the product of the effective axial length of the motor, the width of the permanent magnet, and the remanence of the permanent magnet.

[0017] The magnetic reluctance of the permanent magnet in the first pole range of the permanent magnet motor is calculated by a first product of the vacuum permeability, the relative permeability of the permanent magnet, the width of the permanent magnet, and the effective axial length of the motor, and the magnetic reluctance of the permanent magnet is calculated by the quotient of the thickness of the permanent magnet and the first product.

[0018] In some implementations, the motor parameters include the effective axial length of the motor and the outer radius of the rotor;

[0019] The calculation of the air gap magnetic flux density distribution in the pole tooth region includes: calculating the excitation flux and the second quotient of the fifth product based on the difference between the maximum and minimum values ​​of the rotor outer radius, the effective axial length of the motor, and the arc range of the pole tooth region; calculating the magnetic flux reluctance in the magnetic bridge region and the second sum based on the second sum of the magnetic reluctance of the magnetic bridge region, the magnetic reluctance of the permanent magnet, the magnetic reluctance of the pole slot region, the magnetic reluctance of the pole tooth region, and the leakage magnetic reluctance of the magnetic barrier; and calculating the air gap magnetic flux density distribution in the pole tooth region based on the product of the second and third quotients.

[0020] Alternatively, the air gap magnetic flux density distribution in the pole tooth region can be calculated, including calculating the magnetic flux in the magnetic bridge region based on the product of the excitation magnetic flux and the third quotient; and calculating the air gap magnetic flux density distribution in the pole tooth region based on the quotient of the magnetic flux in the magnetic bridge region and the fifth product.

[0021] In some implementations, the motor parameters include the air gap length;

[0022] The calculation of the air gap magnetic flux density distribution in the pole slot region includes calculating the magnetic circuit length in the stator slot region based on the rotor outer radius and the arc range of the stator slot region; and calculating the air gap magnetic flux density distribution in the pole slot region based on the first quotient of the magnetic circuit length and the air gap length, the first sum of the first quotient and 1, and the quotient of the air gap magnetic flux density distribution in the pole tooth region and the first sum.

[0023] In some implementations, motor parameters include air gap length and the thickness of the magnetic bridge;

[0024] The air gap magnetic flux density distribution in the magnetic bridge region is calculated based on the air gap magnetic flux density distribution in the pole tooth region, the rotor outer radius, the initial radian value of the radian range of the magnetic bridge region, the difference between the maximum and minimum values ​​of the radian range of the magnetic bridge region, the air gap length, the thickness of the magnetic bridge, the vacuum permeability, and the relative permeability of the material in the magnetic bridge region.

[0025] The method for calculating the no-load performance of an embedded permanent magnet motor provided in this application calculates the arc range of the rotor's magnetic pole region and magnetic bridge region, as well as the arc range of the stator's pole slot region and pole tooth region, based on the rotor's initial position. It then calculates the excitation flux, permanent magnet reluctance, pole slot region reluctance, pole tooth region reluctance, magnetic barrier leakage reluctance, and magnetic bridge region reluctance within the first pole region of the permanent magnet motor using the lumped parameter method. Finally, based on the magnetic circuit method and the aforementioned parameters, it calculates the air gap magnetic flux density distribution in the pole slot region, pole tooth region, and magnetic bridge region. Since the lumped parameter method does not require solving complex partial differential equations and can obtain the parameters through algebraic operations alone, and the magnetic circuit method can intuitively correlate the parameters, it improves the computational efficiency of solving the air gap magnetic flux density distribution in each region while ensuring accuracy, thus simplifying the design complexity of the permanent magnet motor. Attached Figure Description

[0026] Figure 1 This is a partial structural schematic diagram of the permanent magnet motor in an embodiment of this application;

[0027] Figure 2 This is a first flowchart of the calculation method in the embodiments of this application;

[0028] Figure 3 This is a flowchart illustrating the calculation of the magnetic reluctance of a permanent magnet in an embodiment of this application;

[0029] Figure 4 This is a flowchart illustrating the calculation of the magnetic reluctance in the pole tooth region in an embodiment of this application;

[0030] Figure 5 This is a flowchart illustrating the calculation of magnetic barrier leakage magnetic resistance in the embodiments of this application;

[0031] Figure 6 This is a flowchart illustrating the calculation of the magnetic reluctance in the magnetic bridge region in an embodiment of this application;

[0032] Figure 7 This is a flowchart illustrating the calculation of the air gap magnetic flux density distribution in the pole slot region in an embodiment of this application;

[0033] Figure 8 This is a flowchart illustrating the calculation of the air gap magnetic flux density distribution in the pole tooth region in an embodiment of this application;

[0034] Figure 9This is a flowchart illustrating the calculation of the air gap magnetic flux density distribution in the pole tooth region in an embodiment of this application;

[0035] Figure 10 This is a flowchart illustrating the air gap magnetic flux density distribution based on the minimum unit pole number in this embodiment of the application.

[0036] Figure 11 This is a schematic diagram of the first and second areas in an embodiment of this application;

[0037] Figure 12 This is a second flowchart of the calculation method in the embodiments of this application. Detailed Implementation

[0038] To enable those skilled in the art to better understand the present application, the technical solutions in specific embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0039] It should be noted that the terms "first," "second," and similar terms used in this application specification and claims do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Similarly, "a" or "one," and similar terms do not indicate a quantity limitation, but rather indicate the presence of at least one. "A plurality" or "several" indicates at least two. Unless otherwise stated, terms such as "front," "back," "left," "right," "lower," and / or "upper" are for illustrative purposes only and are not limited to a location or spatial orientation. Terms such as "comprising" or "including" indicate that the elements or objects preceding "comprising" encompass the elements or objects listed following "comprising" or "including" and their equivalents, and do not exclude other elements or objects. Terms such as "connected" or "linked" are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect.

[0040] The singular forms “a,” “the,” and “the” used in this application specification and appended claims may also include one or more, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein describes the relationship between related objects, indicating that three relationships may exist, for example, A and / or B, which can represent: A alone, A and B simultaneously, or B alone, where A and B can be singular or plural.

[0041] This application provides a method for calculating the no-load performance of an embedded permanent magnet motor, which is applied to permanent magnet motors.

[0042] like Figure 1As shown, the permanent magnet motor 100 includes a rotor 11, a stator 12, and a plurality of permanent magnets 111. The permanent magnet motor 100 has a plurality of poles, and a permanent magnet 111 is embedded inside the rotor 11 of each pole. The rotor 11 has a rotation axis about which it can rotate. The rotor 11 includes a plurality of magnetic isolation bridges 112, which are located on the side of the rotor 11 facing the stator 12 and extend circumferentially along the rotor 11 to prevent magnetic leakage from the permanent magnets 111 and enhance their stability. An air gap 101 extending radially exists between the stator 12 and the rotor 11. The stator 12 has a plurality of winding grooves 121, within which armature windings 122 are embedded.

[0043] In this embodiment, the region through which the main magnetic flux of the permanent magnet 111 passes is defined as the magnetic pole region 102. The area covered by the magnetic isolation bridge 112 is defined as the magnetic bridge region 103, which is located on both sides of the magnetic pole region 102 along the circumferential direction, i.e., there are two magnetic bridge regions 103. The region between two adjacent magnetic isolation bridges 112 of adjacent poles of the permanent magnet motor 100 is defined as the no-excitation region 104. The region on the stator 12 where the winding grooves 121 are formed is defined as the stator slot region 105. The region between two winding grooves 121 is defined as the stator tooth region 106.

[0044] like Figure 2 As shown, in some embodiments, the method for calculating the no-load performance of an embedded permanent magnet motor includes the following steps:

[0045] Step S1: Obtain the motor parameters of the permanent magnet motor 100.

[0046] Among them, the motor parameters include the initial position of rotor 11.

[0047] Step S2: Based on the initial position of rotor 11, calculate the arc range of magnetic pole region 102 and magnetic bridge region 103 of rotor 11, and calculate the arc range of pole slot region 107 and pole tooth region 108 respectively.

[0048] The arc range of the magnetic pole region 102 of the rotor 11 refers to the arc range of the arc formed by the magnetic pole region 102 toward the outer edge of the stator 12; the arc range of the magnetic bridge region 103 of the rotor 11 refers to the arc range of the arc formed by the magnetic bridge region 103 toward the outer edge of the stator 12. The pole slot region 107 is the circumferentially overlapping area of ​​the magnetic pole region 102 and the stator slot region 105 along the radial extension direction of the rotor 11. The pole tooth region 108 is the circumferentially overlapping area of ​​the magnetic pole region 102 and the stator tooth region 106 along the radial extension direction of the rotor 11. Correspondingly, the arc range of the pole slot region 107 refers to the arc range of the arc formed by the pole slot region 107 toward the outer edge of the stator 12; the arc range of the pole tooth region 108 refers to the arc range of the arc formed by the pole tooth region 108 toward the outer edge of the stator 12.

[0049] Step S3: Based on the lumped parameter method, calculate the excitation flux, magnetic reluctance of permanent magnet 111, magnetic reluctance of pole slot region 107, magnetic reluctance of pole tooth region 108, leakage magnetic reluctance of magnetic barrier 113, and magnetic reluctance of magnetic bridge region 103 within the first pole range of permanent magnet motor 100. Among them, the leakage magnetic reluctance of magnetic barrier 113 is the magnetic reluctance of magnetic barrier 113.

[0050] It should be noted that the first pole refers to any magnetic pole in the permanent magnet motor 100.

[0051] In some implementations, the motor parameters also include the width of the permanent magnet 111, the remanence of the permanent magnet 111, the thickness of the permanent magnet 111, the relative permeability of the permanent magnet 111, and the effective axial length of the motor. The remanence of the permanent magnet 111 refers to the magnetic induction intensity that the permanent magnet 111 retains after saturation magnetization and removal of the external magnetic field; the effective axial length of the motor refers to the length of the axial overlap between the rotor 12 and the spindle 11 on the rotation axis.

[0052] When calculating the excitation flux within the first pole range of the permanent magnet motor 100, the excitation flux is calculated based on the product of the effective axial length of the motor, the width of the permanent magnet 111, and the remanence of the permanent magnet 111. In this implementation, the excitation flux satisfies the following relationship:

[0053] (Formula 1)

[0054] In the formula, For excitation flux, For permanent magnet 111 remanence, The width of the permanent magnet is 111. This refers to the effective axial length of the motor.

[0055] like Figure 3 As shown, in some implementations, calculating the magnetic reluctance of the permanent magnet 111 within the first pole range of the permanent magnet motor 100 specifically includes the following steps:

[0056] Step S101: Based on the first product of vacuum permeability, relative permeability of permanent magnet 111, width of permanent magnet 111, and effective axial length of motor.

[0057] Step S102: Calculate the magnetic reluctance of permanent magnet 111 based on the quotient of the thickness of permanent magnet 111 and the first product.

[0058] In this implementation, the magnetic reluctance of the permanent magnet 111 satisfies the following relationship:

[0059]

[0060] In the formula, It is a permanent magnet 111 magnetoresistive material. The thickness of the permanent magnet is 111. The permeability of free space, The relative permeability of permanent magnet 111. This is the first product.

[0061] In some implementations, the motor parameters include the outer radius of the rotor 11, the length of the air gap 101, the thickness of the magnetic barrier 113, the length of the magnetic barrier 113, the thickness of the magnetic isolation bridge 112, and the length of the magnetic isolation bridge 112.

[0062] Wherein, the outer radius of rotor 11 refers to the radial extension length of rotor 11. The length of air gap 101 refers to the radial length of the gap between rotor 11 and stator 12. Rotor 11 has a first groove for embedding permanent magnet 111 and two second grooves connected to the two ends of the first groove. When permanent magnet 111 is embedded in the first groove, the portion of the first groove not accommodating permanent magnet 111 and the entirety of the second grooves constitute the magnetic barrier 113. The thickness of magnetic barrier 113 is the length of magnetic barrier 113 along its own extension direction, which is also the extension direction of the second grooves. The length of magnetic barrier 113 refers to the circumferential length of magnetic barrier 113 along rotor 11. The thickness of magnetic isolation bridge 112 is the radial length of magnetic isolation bridge 112 along rotor 11. The length of magnetic isolation bridge 112 is the circumferential length of magnetic isolation bridge 112 along rotor 11, and the length of magnetic isolation bridge 112 is the same as the length of magnetic barrier 113.

[0063] In some implementations, when calculating the magnetic reluctance of the pole slot region 107 within the first pole range of the permanent magnet motor 100, the magnetic reluctance of the pole slot region 107 is calculated based on the vacuum permeability, the effective axial length of the motor, the outer radius of the rotor 11, the arc range of the stator slot region, and the length of the air gap 101.

[0064] In this implementation, the magnetoresistive region 107 in the pole-slot region satisfies the following relationship:

[0065]

[0066] In the formula, The pole-slot region has a 107 magnetoresistive index. The permeability of free space, The outer radius of rotor 11, The effective axial length of the motor. The length of the air gap is 101, and the curvature range of the stator slot area is... to , The radius of curvature of the starting point of stator slot region 105. The arc of the end point of stator slot region 105.

[0067] in, The following relationship must be satisfied:

[0068]

[0069] In the formula, The arc of the centerline of the stator slot region 105 is the straight line that extends radially along the rotor 11 and bisects the stator slot region 105.

[0070] like Figure 4 As shown, in some implementations, the calculation of the magnetic reluctance of the pole tooth region 108 within the first pole range of the permanent magnet motor 100 includes the following steps:

[0071] Step S201: Obtain the second product based on the difference between the maximum and minimum values ​​of the vacuum permeability, the outer radius of the rotor 11, the effective axial length of the motor, and the arc range of the pole tooth region 108.

[0072] Step S202: Calculate the magnetic reluctance of the pole tooth region 108 based on the quotient of the length of the air gap 101 and the second product.

[0073] In this implementation, the 108 magnetoresistive pole tooth region satisfies the following relationship:

[0074]

[0075] In the formula, This represents the maximum value of the radian range of the polar tooth region 108. This represents the minimum value of the radian range of the polar tooth region 108. This is the difference between the maximum and minimum values ​​of the radian range of the polar tooth region 108. This is the second product.

[0076] like Figure 5 As shown, in some implementations, the calculation of the leakage magnetic resistance of the magnetic barrier 113 within the first pole range of the permanent magnet motor 100 includes the following steps:

[0077] Step S301: Obtain the third product based on the vacuum permeability, the thickness of the magnetic barrier 113, and the effective axial length of the motor.

[0078] Step S302: Calculate the leakage magnetic resistance of the magnetic barrier 113 based on the quotient of the length of the magnetic barrier 113 and the third product.

[0079] In this implementation, the leakage magnetic resistance of the magnetic barrier 113 satisfies the following relationship:

[0080]

[0081] In the formula, The length of magnetic barrier 113, The thickness of magnetic barrier 113, This is the third product.

[0082] like Figure 6As shown, in some implementations, calculating the magnetic reluctance of the magnetic bridge region 103 within the first pole range of the permanent magnet motor 100 includes the following steps:

[0083] Step S401: The fourth product of vacuum permeability, relative permeability of magnetic bridge 112 material, thickness of magnetic bridge 112 and effective axial length of motor.

[0084] Step S402: Calculate the magnetic reluctance of the magnetic bridge region 103 based on the quotient of the length of the magnetic bridge 112 and the fourth product.

[0085] In this implementation, the magnetic reluctance of the magnetic bridge region 103 satisfies the following relationship:

[0086]

[0087] In the formula, The length of the magnetic bridge 112, The relative permeability of the magnetic bridge 112 material is given. The thickness of the magnetic bridge 112, It is the fourth product.

[0088] It should be noted that the relative permeability of the magnetic bridge 112 material satisfies the following relationship:

[0089]

[0090] In the formula, B is the magnetic induction intensity and H is the magnetic field intensity. This application provides a partial BH curve data table of a material as shown in the table below. The relative permeability can be calculated by looking up the table.

[0091] BH Curve Data Table

[0092]

[0093] Step S4: Based on the magnetic circuit method, the arc range of the magnetic pole region 102 and magnetic bridge region 103 of the rotor 11, the arc range of the pole slot region 107 and pole tooth region 108, the excitation flux, the magnetic reluctance of the magnetic bridge region 103, the magnetic reluctance of the permanent magnet 111, the magnetic reluctance of the pole slot region 107, the magnetic reluctance of the pole tooth region 108, and the leakage magnetic reluctance of the magnetic barrier 113, calculate the magnetic flux density distribution of the air gap 101 of the pole slot region 107, the pole tooth region 108, and the magnetic bridge region 103.

[0094] like Figure 7 As shown, in some implementations, the motor parameters include the effective axial length of the motor and the outer radius of the rotor 11. The calculation of the magnetic flux density distribution in the air gap 101 of the pole tooth region 108 includes the following steps:

[0095] Step S501: The fifth product is obtained based on the difference between the maximum and minimum values ​​of the outer radius of rotor 11, the effective axial length of motor, and the arc range of pole tooth region 108.

[0096] Step S502: Calculate the second quotient of the product of the excitation flux and the fifth product.

[0097] Step S503: Obtain the second sum based on the magnetic resistance of the magnetic bridge region 103, the magnetic resistance of the permanent magnet 111, the magnetic resistance of the pole slot region 107, the magnetic resistance of the pole tooth region 108, and the leakage magnetic resistance of the magnetic barrier 113.

[0098] Step S504: Calculate the magnetic resistance of the magnetic bridge region 103 and the second sum to obtain the third quotient.

[0099] Step S505: Calculate the magnetic flux density distribution of the air gap 101 in the pole tooth region 108 based on the product of the second quotient and the third quotient.

[0100] In this implementation, the magnetic flux density distribution in the air gap 101 of the pole tooth region 108 satisfies the following relationship:

[0101]

[0102] In the formula, The magnetic flux density distribution in the air gap 101 of the pole tooth region 108 is as follows: The outer radius of rotor 11, The fifth product, For the second sum, For the second quotient, For the third merchant.

[0103] like Figure 8 As shown, in some other implementations, calculating the magnetic flux density distribution of the air gap 101 in the pole tooth region 108 includes the following steps:

[0104] Step S601: The fifth product is obtained based on the difference between the maximum and minimum values ​​of the outer radius of rotor 11, the effective axial length of motor, and the arc range of pole tooth region 108.

[0105] Step S602: Obtain the second sum based on the magnetic resistance of the magnetic bridge region 103, the magnetic resistance of the permanent magnet 111, the magnetic resistance of the pole slot region 107, the magnetic resistance of the pole tooth region 108, and the leakage magnetic resistance of the magnetic barrier 113.

[0106] Step S603: Calculate the third quotient of the magnetic resistance of the magnetic bridge region 103 and the second sum.

[0107] Step S604: Calculate the magnetic flux of the magnetic bridge region 103 based on the product of the excitation flux and the third quotient.

[0108] Step S605: Calculate the magnetic flux distribution of the air gap 101 in the pole tooth region 108 based on the quotient of the magnetic flux in the magnetic bridge region 103 and the fifth product.

[0109] In this implementation, the magnetic flux density distribution in the air gap 101 of the pole tooth region 108 satisfies the following relationship:

[0110]

[0111] In the formula, The magnetic flux density distribution in the air gap 101 of the pole tooth region 108 is as follows: The magnetic flux is 103 in the magnetic bridge region.

[0112] The magnetic flux in the magnetic bridge region 103 satisfies the following relationship:

[0113]

[0114] In some implementations, the motor parameters include the length of the air gap 101 and the thickness of the magnetic bridge 112. The calculation of the magnetic flux density distribution of the air gap 101 in the magnetic bridge region 103 includes:

[0115] The magnetic flux density distribution of the air gap 101 in the pole tooth region 108 is calculated based on the magnetic flux density distribution of the air gap 101 in the pole tooth region 108, the outer radius of the rotor 11, the initial radian value of the radian range of the magnetic bridge region 103, the difference between the maximum and minimum values ​​of the radian range of the magnetic bridge region 103, the length of the air gap 101, the thickness of the magnetic isolation bridge 112, the vacuum permeability, and the relative permeability of the material in the magnetic bridge region 103.

[0116] In this implementation, the magnetic flux density distribution in the air gap 101 of the magnetic bridge region 103 satisfies the following relationship:

[0117]

[0118] In the formula, This is the starting radian value of the radian range of the magnetic bridge region 103, i.e. and The radian values ​​are the same. It is the difference between the maximum and minimum values ​​of the radian range of the magnetic bridge region 103.

[0119] in, The following relationship must be satisfied:

[0120]

[0121] In the formula, The relative permeability of the material in the magnetic bridge region 103 satisfies And it can be obtained by querying the BH table.

[0122] In some implementations, the motor parameters include the number of poles and the number of slots. The number of poles refers to the total number of magnetic poles formed by the permanent magnets 111; the number of slots refers to the number of winding grooves 121 formed in the stator 12.

[0123] like Figure 9 As shown, in some implementations, the motor parameters include the length of the air gap 101. Calculating the magnetic flux density distribution of the air gap 101 in the pole slot region 107 includes the following steps:

[0124] Step S701: Based on the outer radius of rotor 11 and the arc range of stator slot 105, calculate the magnetic circuit length in stator slot 105.

[0125] Step S702: Based on the length of the magnetic circuit and the length of the air gap 101, obtain the first quotient, and the first quotient and 1 to obtain the first sum.

[0126] Step S703: Calculate the magnetic flux density distribution of the air gap 101 in the pole tooth region 108 based on the quotient of the magnetic flux density distribution of the air gap 101 in the pole tooth region 108 and the first sum.

[0127] In this implementation, the magnetic flux density distribution of the air gap 101 in the pole slot region 107 satisfies the following relationship:

[0128]

[0129] In the formula, The magnetic flux density distribution of the air gap 101 in the pole slot region 107 is shown. The length of the magnetic circuit. As the first merchant, This is the first total.

[0130] like Figure 10 As shown, in some implementations, the calculation method further includes the following steps:

[0131] Step S801: Based on the greatest common divisor of the number of poles and the number of slots, calculate the minimum number of symmetrical units, the minimum number of slots, and the minimum number of poles of the permanent magnet motor 100.

[0132] It should be noted that the minimum number of symmetrical elements, the minimum number of slots, and the minimum number of poles are all integers.

[0133] In some implementations, the minimum number of symmetric units satisfies the following relationship:

[0134]

[0135] In the formula, GCD is a function for finding the greatest common divisor. For the number of slots, It is an extreme number.

[0136] In some implementations, the minimum number of cell slots satisfies the following relationship:

[0137]

[0138] In the formula, This represents the minimum number of slots per unit.

[0139] In some implementations, the minimum unit series satisfies the following relationship:

[0140]

[0141] In the formula, It is the smallest unit level.

[0142] Step S802: Determine whether the minimum unit pole number is equal to 1. If yes, proceed to step S803; otherwise, proceed to step S804.

[0143] It should be noted that when the minimum unit number of stages is 1, the motor is an integer slot motor, and the magnetic flux density of the positive and negative poles of the motor is symmetrically distributed; when the minimum unit number of poles is greater than 1, the motor is a fractional slot motor, and the motor under each pole in the minimum symmetrical unit of the motor is asymmetrical. The permanent magnet motor 100 includes the nth pole adjacent to the (n-1)th pole, where n is a positive integer greater than 1 and equal to the minimum unit number of poles.

[0144] Step S803: Output the magnetic flux density distribution of all air gaps 101.

[0145] Step S804: Calculate the magnetic flux density distribution sets of the air gap 101 in the pole slot region 107, pole tooth region 108 and magnetic bridge region 103 within the range of the second pole to the nth pole of the permanent magnet motor 100.

[0146] It should be noted that the method for calculating the magnetic flux density distribution set of the air gap 101 is the same as the method for calculating the magnetic flux density distribution of the air gap 101 in the pole slot region 107, pole tooth region 108 and magnetic bridge region 103 within the first pole range, and will not be repeated here.

[0147] Step S805: Based on each air gap 101 magnetic flux density distribution in the air gap 101 magnetic flux density distribution set and all air gap 101 magnetic flux density distributions within the first pole range, determine the air gap 101 magnetic flux density distribution curves within the range from the first pole to the nth pole of the permanent magnet motor 100.

[0148] Step S806: Based on the magnetic flux density distribution curve of air gap 101, the area enclosed by the horizontal axis and the air gap 101 magnetic flux density distribution curve with the vertical axis greater than 0 is defined as the first area, and the area enclosed by the horizontal axis and the air gap 101 magnetic flux density distribution curve with the vertical axis less than 0 is defined as the second area. The bias of the air gap 101 magnetic flux density distribution curve is determined based on the difference between the first area and the second area.

[0149] The bias is generated by the harmonics introduced in the calculation.

[0150] like Figure 11As shown, the solid blue line represents the magnetic flux density distribution curve of this method, and the dashed red line represents the magnetic flux density distribution curve of the finite element simulation. The first area S1 and the second area S2 are distributed at the upper and lower ends of the horizontal axis, and the offset satisfies the following relationship:

[0151] S1+S0=S2 (Formula 18)

[0152] In the formula, S0 is the bias, S1 is the first area, and S2 is the second area.

[0153] Step S807: Based on the bias, update the magnetic flux density distribution curve of the air gap 101 in the range of the first pole to the nth pole of the permanent magnet motor 100.

[0154] Through the above steps, based on the greatest common divisor of the number of poles and slots, the minimum number of symmetrical units, the minimum number of slots and the minimum number of poles of the permanent magnet motor 100 are calculated. Based on the minimum number of poles, the magnetic flux density distribution sets of the air gap 101 of different poles are calculated or output. When the bias of the magnetic flux density distribution curve of the air gap 101 is not 0, the magnetic flux density distribution curve of the air gap 101 is updated based on the bias, thereby improving the accuracy of calculating the magnetic flux density distribution curve of the air gap 101.

[0155] The method for calculating the no-load performance of the embedded permanent magnet motor provided in this application calculates the arc range of the magnetic pole region 102 and magnetic bridge region 103 of the rotor 11 and the arc range of the pole slot region 107 and pole tooth region 108 of the stator 12 based on the initial position of the rotor 11. It calculates the excitation flux, magnetic reluctance of the permanent magnet 111, magnetic reluctance of the pole slot region 107, magnetic reluctance of the pole tooth region 108, leakage magnetic reluctance of the magnetic barrier 113, and magnetic reluctance of the magnetic bridge region 103 within the first pole range of the permanent magnet motor 100 based on the lumped parameter method. Based on the magnetic circuit method and the above parameters, it calculates the magnetic flux density distribution of the air gap 101 in the pole slot region 107, pole tooth region 108, and magnetic bridge region 103. Since the lumped parameter method does not require solving complex partial differential equations and can obtain each parameter through algebraic operations only, and the magnetic circuit method can intuitively correlate each parameter, it improves the calculation efficiency of solving the air gap magnetic flux density distribution in each region while ensuring accuracy, thus simplifying the design complexity of the permanent magnet motor 100.

[0156] like Figure 12 As shown, in some implementations, the calculation method further includes the following steps:

[0157] Step S5: Based on the magnetic flux density distribution of the air gap 101 in the magnetic bridge region 103 and the BH curve of the iron core, determine the relative permeability of the material in the magnetic bridge region 103.

[0158] The relative permeability of the material in the magnetic bridge region 103 was obtained through iteration.

[0159] Step S6: Based on the preset error convergence value, update the relative permeability of the material in the magnetic bridge region 103.

[0160] It should be noted that if the residual of the relative permeability of the material in the magnetic bridge region 103 during the iteration process is greater than the preset error convergence value, the iteration continues; if it is not greater than the preset error convergence value, the iteration stops, and the last iteration result is used as the updated relative permeability of the material in the magnetic bridge region 103.

[0161] When calculating the magnetic flux density distribution of the air gap 101 in the magnetic bridge region 103, the relative permeability of the material in the magnetic bridge region 103 can be updated through steps S5 and S6.

[0162] Step S7: Based on the material relative permeability of the updated magnetic bridge region 103, calculate the magnetic reluctance of the updated magnetic bridge region 103, and calculate the magnetic flux density distribution of the air gap 101 of the updated magnetic bridge region 103.

[0163] It should be noted that the calculation and updating of each parameter in steps S5 to S7 can refer to the methods in steps S1 to S4, and will not be repeated here to avoid repetition.

[0164] Through the above steps, the relative permeability of the material of the magnetic bridge region 103 is updated, and based on the updated relative permeability of the material of the magnetic bridge region 103, the updated magnetic reluctance of the magnetic bridge region 103 and the air gap magnetic flux density distribution of the magnetic bridge region 103 are calculated. Since the updated relative permeability of the material of the magnetic bridge region 103 is more accurate, the accuracy of the air gap magnetic flux density distribution of the magnetic bridge region 103 obtained based on the relative permeability of the material is improved.

[0165] In some implementations, the permanent magnet flux linkage at different initial positions of the rotor 11 is integrated and multiplied by the number of turns and the number of armature windings 122 to obtain the permanent magnet flux linkage at different initial positions of the rotor 11. The permanent magnet flux linkage is the sum of the permanent magnet excitation flux linkage linked by the windings and the armature reaction flux linkage. Differentiating each permanent magnet flux linkage yields the back electromotive force of the permanent magnet motor 100.

[0166] It should be understood that those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of the appended claims.

Claims

1. A method for calculating the no-load performance of an embedded permanent magnet motor, characterized in that, include: Obtain the motor parameters of the permanent magnet motor, including the initial position of the rotor; Based on the initial position of the rotor, calculate the arc range of the rotor's magnetic pole region and magnetic bridge region; The arc range of the pole slot region and the pole tooth region are calculated respectively. The pole slot region is the circumferentially overlapping area of ​​the magnetic pole region and the stator slot region along the radial extension direction of the rotor. The pole tooth region is the circumferentially overlapping area of ​​the magnetic pole region and the stator tooth region along the radial extension direction of the rotor. Based on the lumped parameter method, the excitation flux, permanent magnet reluctance, pole slot region reluctance, pole tooth region reluctance, magnetic barrier leakage reluctance, and magnetic bridge region reluctance within the first pole range of the permanent magnet motor are calculated, where the magnetic barrier leakage reluctance is the magnetic barrier reluctance. Based on the magnetic circuit method, the arc range of the magnetic pole region and magnetic bridge region of the rotor, the arc range of the pole slot region and pole tooth region, the excitation magnetic flux, the magnetic reluctance of the magnetic bridge region, the magnetic reluctance of the permanent magnet, the magnetic reluctance of the pole slot region, the magnetic reluctance of the pole tooth region, and the magnetic barrier leakage magnetic reluctance, the air gap magnetic flux distribution of the pole slot region, the pole tooth region, and the magnetic bridge region is calculated. The motor parameters include the number of poles and the number of slots; The calculation method further includes: Based on the greatest common divisor of the number of poles and the number of slots, calculate the minimum number of symmetrical units, the minimum number of slots, and the minimum number of poles of the permanent magnet motor. The calculation method includes: When the minimum unit pole number is equal to 1, output all the air gap magnetic flux density distributions; When the minimum unit pole number is greater than 1, the permanent magnet motor includes an nth pole adjacent to the (n-1)th pole, where n is a positive integer greater than 1 and equal to the minimum unit pole number; The calculation method includes: When the minimum unit pole number is greater than 1, calculate the air gap magnetic flux density distribution sets of the pole slot region, the pole tooth region, and the magnetic bridge region within the range of the second pole to the nth pole of the permanent magnet motor, respectively; Based on each air gap magnetic flux density distribution in the set of air gap magnetic flux density distributions and all the air gap magnetic flux density distributions within the first pole range, the air gap magnetic flux density distribution curve within the range from the first pole to the nth pole of the permanent magnet motor is determined; Based on the air gap magnetic flux density distribution curve, the area enclosed by the horizontal axis and the air gap magnetic flux density distribution curve with the vertical axis greater than 0 is defined as the first area, and the area enclosed by the horizontal axis and the air gap magnetic flux density distribution curve with the vertical axis less than 0 is defined as the second area. The bias of the air gap magnetic flux density distribution curve is determined based on the difference between the first area and the second area. Based on the bias, the air gap magnetic flux density distribution curve of the permanent magnet motor is updated within the range of the first pole to the nth pole.

2. The calculation method according to claim 1, characterized in that, The calculation method further includes: Based on the air gap magnetic flux density distribution in the magnetic bridge region and the BH curve of the iron core, the relative permeability of the material in the magnetic bridge region is determined. The relative permeability of the material in the magnetic bridge region is updated based on a preset error convergence value. Based on the updated relative permeability of the material in the magnetic bridge region, the updated magnetic reluctance of the magnetic bridge region is calculated, and the updated air gap magnetic flux density distribution in the magnetic bridge region is also calculated.

3. The calculation method according to claim 1, characterized in that, The magnetic pole region is the area through which the main magnetic flux of the permanent magnet passes, and the magnetic bridge region is the area covered by the magnetic isolation bridge.

4. The calculation method according to claim 1, characterized in that, The motor parameters include the effective axial length of the motor, the outer radius of the rotor, the air gap length, the thickness of the magnetic barrier, the length of the magnetic barrier, the thickness of the magnetic isolation bridge, and the length of the magnetic isolation bridge. The calculation of the pole slot region magnetic reluctance within the first pole range of the permanent magnet motor includes: The magnetic reluctance of the pole slot region is calculated based on the vacuum permeability, the effective axial length of the motor, the outer radius of the rotor, the arc range of the stator slot region, and the air gap length. The calculation of the magnetic reluctance of the pole tooth region within the first pole range of the permanent magnet motor includes: The magnetic reluctance of the pole tooth region is calculated based on the second product of the difference between the maximum and minimum values ​​of the vacuum permeability, the rotor outer radius, the effective axial length of the motor, and the arc range of the pole tooth region, and based on the quotient of the air gap length and the second product. The calculation of the magnetic barrier leakage resistance within the first pole range of the permanent magnet motor includes: The leakage magnetic resistance of the magnetic barrier is calculated based on the third product of the vacuum permeability, the thickness of the magnetic barrier, and the effective axial length of the motor, and based on the quotient of the length of the magnetic barrier and the third product. The calculation of the magnetic reluctance of the magnetic bridge region within the first pole range of the permanent magnet motor includes: The magnetic reluctance of the magnetic bridge region is calculated based on the fourth product of the vacuum permeability, the relative permeability of the magnetic bridge material, the thickness of the magnetic bridge, and the effective axial length of the motor, and based on the quotient of the length of the magnetic bridge and the fourth product.

5. The calculation method according to claim 4, characterized in that, The motor parameters include permanent magnet width, permanent magnet remanence, permanent magnet thickness, and relative permeability of the permanent magnet; The calculation of the excitation flux within the first pole range of the permanent magnet motor includes: The excitation flux is calculated based on the product of the effective axial length of the motor, the width of the permanent magnet, and the remanence of the permanent magnet. The calculation of the permanent magnet reluctance within the first pole range of the permanent magnet motor includes: The magnetic reluctance of the permanent magnet is calculated based on a first product of the vacuum permeability, the relative permeability of the permanent magnet, the width of the permanent magnet, and the effective axial length of the motor, and based on the quotient of the thickness of the permanent magnet and the first product.

6. The calculation method according to claim 1, characterized in that, The motor parameters include the effective axial length of the motor and the outer radius of the rotor. The calculation of the air gap magnetic flux density distribution in the pole tooth region includes: The second quotient of the excitation flux and the fifth product is calculated based on the fifth product of the difference between the maximum and minimum values ​​of the rotor outer radius, the effective axial length of the motor, and the arc range of the pole tooth region. Based on the second sum of the magnetic reluctance of the magnetic bridge region, the magnetic reluctance of the permanent magnet, the magnetic reluctance of the pole slot region, the magnetic reluctance of the pole tooth region, and the magnetic barrier leakage magnetic reluctance, calculate the third quotient of the magnetic reluctance of the magnetic bridge region and the second sum; The air gap magnetic flux density distribution in the pole tooth region is calculated based on the product of the second quotient and the third quotient. Alternatively, the calculation of the air gap magnetic flux density distribution in the pole tooth region includes: The magnetic flux in the magnetic bridge region is calculated based on the product of the excitation flux and the third quotient. The air gap magnetic flux distribution in the pole tooth region is calculated based on the quotient of the magnetic flux in the magnetic bridge region and the fifth product.

7. The calculation method according to claim 6, characterized in that, The motor parameters include the air gap length; The calculation of the air gap magnetic flux density distribution in the pole slot region includes: Based on the rotor outer radius and the arc range of the stator slot region, calculate the magnetic circuit length in the stator slot region; Based on the first quotient of the magnetic circuit length and the air gap length, the first sum of the first quotient and 1, and based on the quotient of the air gap magnetic flux density distribution of the pole tooth region and the first sum, the air gap magnetic flux density distribution of the pole slot region is calculated.

8. The calculation method according to claim 6, characterized in that, The motor parameters include the air gap length and the thickness of the magnetic bridge; The calculation of the air gap magnetic flux density distribution in the magnetic bridge region includes: The air gap magnetic flux density distribution of the magnetic bridge region is calculated based on the air gap magnetic flux density distribution of the pole tooth region, the outer radius of the rotor, the starting radian value of the radian range of the magnetic bridge region, the difference between the maximum and minimum values ​​of the radian range of the magnetic bridge region, the air gap length, the thickness of the magnetic bridge, the vacuum permeability, and the relative permeability of the material in the magnetic bridge region.

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