A design method for variable flux memory motor based on a new hysteresis model

Abstract

The present invention provides a variable flux memory motor design method based on a novel hysteresis model, comprising: step S1, obtaining a first magnetization state point of a permanent magnet in the permanent magnet hysteresis model; step S2, determining whether magnetization or demagnetization is required: if so, proceeding to step S3; if not, returning to step S1; step S3, applying a magnetization current or a demagnetization current to update the magnetic field strength; step S4, determining a second magnetization state point after the first magnetization state point is moved at the current moment and updating the first-order magnetization rise curve or the first-order magnetization fall curve for the first time; step S5, removing the magnetization current or the demagnetization current; step S6, determining a third magnetization state point after the second magnetization state point is moved at the current moment and updating the first-order magnetization rise curve or the first-order magnetization fall curve for the second time, retaining the third magnetization state point for calculating motor parameters. The present invention has the beneficial effect of accurately simulating the magnetization characteristics of aluminum nickel cobalt materials and reducing complexity.

Description

Technical Field

[0001] The present invention relates to the technical field of motor design and manufacture, and in particular to a design method of a variable flux memory motor based on a novel hysteresis model. Background Art

[0002] As a device that converts electrical energy into mechanical energy, the motor is widely used in industry, national defense, and daily life. With the development of science and technology, permanent magnet synchronous motors have become a research hotspot in the motor field due to their significant features such as high efficiency and high power density. Permanent magnet synchronous motors usually use permanent magnets as the magnetic source and achieve speed and power control by adjusting the air gap flux. However, traditional permanent magnet motors have some problems, such as the difficulty in adjusting the air gap flux and limited weak magnetic capability.

[0003] To solve these problems of traditional permanent magnet synchronous motors, researchers proposed a variable flux memory motor (VFMM). The variable flux memory motor uses low-coercive force permanent magnet aluminum nickel cobalt and changes the magnetization state of the permanent magnet by applying direct-axis pulse current, thereby achieving adjustment of the air gap flux. This method avoids the copper loss caused by continuous direct-axis current during the weak magnetic process, improves the efficiency of the motor, and has a wide air gap flux adjustment range, so the motor has a wide speed operating range.

[0004] The core of the variable flux memory motor to achieve air gap flux regulation lies in the unique magnetizing characteristics of the low coercive force permanent magnet material AlNiCo. Therefore, accurate calculation of the magnetizing performance of AlNiCo is a key. The hysteresis model currently commonly used in low coercive force permanent magnet materials is the parallelogram model. Although it can simulate the magnetizing characteristics of permanent magnets, it has problems such as inaccurate prediction of magnetizing performance and large errors in simulation results. Therefore, how to propose a new hysteresis model that can accurately simulate the magnetizing characteristics of AlNiCo materials while reducing complexity as much as possible is an urgent problem to be solved. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to accurately simulate the magnetization characteristics of aluminum nickel cobalt materials and reduce complexity. In order to overcome the defects of the above-mentioned existing technologies (or related technologies), the present invention provides a variable flux memory motor design method based on a new hysteresis model.

[0006] The present invention provides a variable flux memory motor design method based on a novel hysteresis model, which is applied to a permanent magnet hysteresis model. The permanent magnet hysteresis model is formed by connecting a main magnetization curve and a main demagnetization curve to form a closed outer contour. Multiple first-order magnetization rising curves and multiple first-order magnetization falling curves are connected between the main magnetization curve and the main demagnetization curve. The variable flux memory motor design method includes the following steps:

[0007] Step S1, controlling a variable flux memory motor to operate, and obtaining, for any permanent magnet in the variable flux memory motor, a first magnetization state point of the permanent magnet in the permanent magnet hysteresis model;

[0008] Step S2: Determine whether the permanent magnet needs to be magnetized or demagnetized:

[0009] If yes, go to step S3;

[0010] If not, return to step S1;

[0011] Step S3, applying a magnetizing current or a demagnetizing current to the permanent magnet to update the magnetic field strength so that the first magnetization state point moves along the first-order magnetization rising curve or the first-order magnetization falling curve;

[0012] Step S4, determining a second magnetization state point after the first magnetization state point moves at the current moment and updating the first-order magnetization rising curve or the first-order magnetization falling curve for the first time;

[0013] Step S5, removing the magnetizing current or the demagnetizing current to move the second magnetization state point along the first-order magnetization rising curve or the first-order magnetization falling curve after the first update;

[0014] Step S6: determining a third magnetization state point after the second magnetization state point moves at the current moment, updating the first-order magnetization rising curve or the first-order magnetization falling curve for the second time, and retaining the third magnetization state point for calculating motor parameters.

[0015] Compared with the existing technology, the variable flux memory motor design method based on the new hysteresis model in this application has the following advantages:

[0016] In the present application, the first magnetization state point is acquired through step S1, the charging and demagnetization requirements are determined through step S2, the charging and demagnetization currents are applied through step S3, the second magnetization state point is determined through step S4, the charging and demagnetization currents are removed through step S5, and the third magnetization state point is determined through step S6. The magnetization state points are used to more realistically represent the magnetization characteristics of the aluminum nickel cobalt material. The movement of the magnetization state points on the first-order magnetization rising curve or the first-order magnetization falling curve can more accurately simulate the magnetization characteristics of the nonlinear material aluminum nickel cobalt permanent magnet, thereby improving the accuracy of the mapping relationship between parameters such as the motor air gap flux and the charging and demagnetization currents, thereby improving the accuracy of the motor design. In addition, the permanent magnet hysteresis model in the present application does not require a large amount of experimental data to construct a distribution function model, which greatly improves the calculation efficiency, achieves accurate simulation of the magnetization characteristics of the aluminum nickel cobalt material, and reduces complexity.

[0017] In a possible implementation manner, before executing step S1, the method further includes:

[0018] The main magnetization curve and the main demagnetization curve are connected end to end to form a closed area to obtain two curve connection points, and the curve connection point located in the first quadrant is used as the connection point corresponding to the positive maximum value, and the curve connection point located in the fourth quadrant is used as the connection point corresponding to the reverse maximum value.

[0019] In a possible implementation, before executing step S1, the main demagnetization curve is defined as:

[0020] When the first magnetization state point is demagnetized at the positive maximum value, the first magnetization state point moves along the main demagnetization curve.

[0021] In a possible implementation, before executing step S1, the main magnetization curve is defined as:

[0022] When the first magnetization state point is magnetized at the reverse maximum value, the first magnetization state point moves along the main magnetization curve.

[0023] In a possible implementation, before executing step S1, each of the first-order magnetization rising curves is defined as a family of curves showing changes in the first magnetization state point and the second magnetization state point during magnetization.

[0024] In a possible implementation, before executing step S1, each of the first-order magnetization decline curves is defined as a family of curves showing changes in the first magnetization state point and the second magnetization state point during demagnetization.

[0025] In a possible implementation, the variable flux memory motor design method further includes a motor parameter calculation process, which includes:

[0026] Step A1: Determine whether the variable flux memory motor needs to expand its speed range:

[0027] If yes, go to step S1 and go to step A2 after obtaining the third magnetization state point;

[0028] If not, return to step A1;

[0029] Step A2: Calculate the corresponding motor parameters according to the third magnetization state point and the magnetic field strength at the current moment. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a flow chart of the steps of the present invention;

[0031] Figure 2 Schematic diagram of the structure of the permanent magnet hysteresis model of the present invention;

[0032] Figure 3 Schematic diagram of the magnetization state point movement of the present invention. DETAILED DESCRIPTION

[0033] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of the present application and are not intended to limit the scope of protection of the embodiments of the present application. Those skilled in the art may adjust them as needed to suit specific application scenarios.

[0034] The present application is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] See also Figure 1 The present invention discloses a method for designing a variable flux memory motor based on a novel hysteresis model, comprising:

[0036] Step S1, controlling a variable flux memory motor to operate, and obtaining a first magnetization state point of any permanent magnet in the variable flux memory motor in a permanent magnet hysteresis model;

[0037] Step S2: Determine whether the permanent magnet needs to be magnetized or demagnetized:

[0038] If yes, go to step S3;

[0039] If not, return to step S1;

[0040] Step S3, applying a magnetizing current or a demagnetizing current to the permanent magnet to update the magnetic field strength so that the first magnetization state point moves along the first-order magnetization rising curve or the first-order magnetization falling curve;

[0041] Step S4, determining a second magnetization state point after the first magnetization state point moves at the current moment and updating the first-order magnetization rising curve or the first-order magnetization falling curve for the first time;

[0042] Step S5, removing the magnetizing current or the demagnetizing current so that the second magnetization state point moves along the first-order magnetization rising curve or the first-order magnetization falling curve after the first update;

[0043] Step S6: determining a third magnetization state point after the second magnetization state point moves at the current moment, and updating the first-order magnetization rising curve or the first-order magnetization falling curve for the second time, and retaining the third magnetization state point for calculating motor parameters.

[0044] The significance of the permanent magnet hysteresis model in this application is: since the magnetization intensity is not a simple linear relationship with the change of the magnetic field intensity, but has a hysteresis, it is very important to accurately describe the relationship between them. The role of the permanent magnet hysteresis model is to describe the magnetization intensity B of the permanent magnet as accurately as possible, as the relationship changes with the magnetic field intensity H of the environment in which the permanent magnet is located. The permanent magnet hysteresis model is the prerequisite for subsequent design calculations. The accuracy of the permanent magnet hysteresis model affects the accuracy of subsequent design calculations.

[0045] The definition of the magnetization state point in this application is: the permanent magnet in the operation of the variable flux memory motor will correspond to a certain magnetization state point in the permanent magnet hysteresis model, and will change with the change of the operating state of the variable flux memory motor. A more accurate permanent magnet hysteresis model can accurately determine the magnetization state point of the permanent magnet, and at the same time can improve the simulation accuracy of the finite element calculation method or the finite volume calculation method for describing the actual operating state of the variable flux memory motor.

[0046] The embodiment of the present application mainly proposes a new type of permanent magnet hysteresis model, including the charging and demagnetization principle of the permanent magnet hysteresis model and the operation mechanism in the electromagnetic design software, wherein the permanent magnet hysteresis model includes a main magnetization curve, a main demagnetization curve, a first-order magnetization decrease curve, and a first-order magnetization increase curve. The meanings of the main magnetization curve and the main demagnetization curve are: when the magnetization state point is at the positive maximum value, if demagnetization is performed at this time, the magnetization state point will move along the main demagnetization curve; when the magnetization state point is at the reverse maximum value, if magnetization is performed at this time, the magnetization state point will move along the main magnetization curve. The main magnetization curve and the main demagnetization curve together constitute the outer contour of the permanent magnet hysteresis model. The magnetization state point of the permanent magnet is always determined above and within the outer contour of the permanent magnet hysteresis model. The structure of the permanent magnet hysteresis model is as follows: Figure 2 As shown in the figure, the meaning of the first-order magnetization decrease curve is: it refers to the path curve of the magnetization state point change during demagnetization. Because the initial magnetization state points before demagnetization are different, the magnetization decrease curve is a family of curves formed by various curves, collectively referred to as the first-order magnetization decrease curve; the meaning of the first-order magnetization increase curve is: it refers to the path curve of the magnetization state point change during magnetization. Because the initial magnetization state points before magnetization are different, the magnetization increase curve is a family of curves formed by various curves, collectively referred to as the first-order magnetization increase curve.

[0047] The charging and demagnetization principle of the permanent magnet hysteresis model is:

[0048] After the permanent magnet determines the magnetization state point, there will be a first-order magnetization decrease curve and a first-order magnetization increase curve corresponding to this point. During magnetization, the magnetization state point increases along the first-order magnetization increase curve corresponding to this moment, and during demagnetization, it decreases along the first-order magnetization decrease curve. After charging and demagnetization, a new magnetization state point is obtained, and the updated magnetization state point corresponds to the first-order magnetization decrease curve and the first-order magnetization increase curve.

[0049] like Figure 3 As shown in the figure, when the variable flux memory motor is running, the permanent magnet magnetization state point is point A. At this time, l1 is its corresponding first-order magnetization rising curve, and l2 is the first-order magnetization falling curve. At this time, if you want to increase the speed, demagnetize the permanent magnet, apply a demagnetization current, and the magnetic field intensity H increases in the negative direction. The magnetization state point decreases along l2 to B. At this time, the first-order magnetization rising curve l3 and the first-order magnetization falling curve l2 are updated. At this time, the demagnetization current is canceled, the magnetic field intensity H decreases in the positive direction, and the magnetization state point changes along l3 to point C. At this time, the first-order magnetization rising curve l3 and the first-order magnetization falling curve l4 are updated. After demagnetization is completed, the magnetization state point C is added to the design calculation.

[0050] The charging and demagnetization operation mechanism of the new permanent magnet hysteresis type in the design software is:

[0051] When the variable flux memory motor needs to expand its speed range, the d-axis current is applied, and the software calculates the magnetic field strength at this moment. Based on the charging and demagnetization principle of the permanent magnet hysteresis model, the updated magnetization strength of the permanent magnet is determined, and the calculation and design begin using the updated parameters of the permanent magnet.

[0052] Compared with the existing technology, the beneficial effects of the technical solution of the present application are as follows: 1. High-precision simulation: The new permanent magnet hysteresis model proposed in this application not only takes into account the real magnetization characteristics of aluminum nickel cobalt materials, but also greatly reduces the complexity of calculation. This permanent magnet hysteresis model can more accurately simulate the magnetization characteristics of nonlinear material aluminum nickel cobalt permanent magnets, improve the accuracy of the mapping relationship between parameters such as the motor air gap flux and the charging and demagnetizing current, thereby improving the accuracy of motor design; 2. Improved calculation efficiency: Compared with the Preisach model, the permanent magnet hysteresis model of this application does not require a large amount of experimental data to construct a distribution function model, which greatly improves the calculation efficiency; 3. Wide application: The permanent magnet hysteresis model of this application is not only suitable for variable flux memory motors , and is also suitable for other motor designs that require precise simulation of magnetization characteristics. In addition, since the computational complexity of the permanent magnet hysteresis model of this application is low, it is also suitable for rapid simulation and optimization of large-scale motor designs; 4. Improve the speed regulation performance of the motor: Since the permanent magnet hysteresis model of this application can more accurately simulate the magnetization characteristics of aluminum nickel cobalt materials, the operating point of the Alnico permanent magnet under different charging and demagnetization currents can be more accurately determined, thereby improving the speed regulation performance of the variable flux memory motor. Specifically, the permanent magnet hysteresis model of this application can help designers better understand and predict the magnetization state and air gap flux changes of the variable flux memory motor, thereby optimizing the design and control of the variable flux memory motor and improving the efficiency and speed regulation performance of the variable flux memory motor.

[0053] Due to the advanced nature of the technical solution of the present application, it can be widely used in application fields such as motor design and manufacturing, magnetic material science and control system engineering: In the field of motor design and manufacturing, the new permanent magnet hysteresis model proposed in the technical solution of the present application can greatly improve the calculation accuracy of the magnetization performance of low coercive force permanent magnets, thereby optimizing the design of variable flux memory motors, which can not only improve the efficiency of variable flux memory motors and expand the speed operating range of variable flux memory motors, but also reduce the manufacturing cost of variable flux memory motors and improve market competitiveness; In the field of magnetic material science, the new permanent magnet of the technical solution of the present application The hysteresis model can more accurately simulate the magnetization characteristics of the nonlinear material aluminum nickel cobalt permanent magnet, which has important scientific significance for studying the magnetization properties of aluminum nickel cobalt materials and developing new magnetic materials; in the field of control system engineering, the new permanent magnet hysteresis model of the technical solution of the present application can be used to design and optimize control strategies, thereby improving the control accuracy and response speed of the variable flux memory motor, which has important engineering value for improving the dynamic performance and stability of the variable flux memory motor; in general, the new permanent magnet hysteresis model of the technical solution of the present application has broad application prospects and market demand, and is expected to promote the development and progress of related technical fields.

[0054] In the description of the present application, the description with reference to the terms "one embodiment", "some embodiments", "in the present embodiment", "specific example", or "some examples" means that the specific features, mechanisms, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present application. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, mechanisms, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and the features of different embodiments or examples, unless they are contradictory.

[0055] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in the present application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A design method for a variable flux memory motor based on a new hysteresis model, characterized in that: Applied to a permanent magnet hysteresis model, the permanent magnet hysteresis model is formed by connecting a main magnetization curve and a main demagnetization curve to form a closed outer contour, and multiple first-order magnetization rising curves and multiple first-order magnetization falling curves are connected between the main magnetization curve and the main demagnetization curve. The variable flux memory motor design method includes the following steps: Step S1, controlling a variable flux memory motor to operate, and obtaining, for any permanent magnet in the variable flux memory motor, a first magnetization state point of the permanent magnet in the permanent magnet hysteresis model; Step S2: Determine whether the permanent magnet needs to be magnetized or demagnetized: If yes, go to step S3; If not, return to step S1; Step S3, applying a magnetizing current or a demagnetizing current to the permanent magnet to update the magnetic field strength so that the first magnetization state point moves along the first-order magnetization rising curve or the first-order magnetization falling curve; Step S4, determining a second magnetization state point after the first magnetization state point moves at the current moment and updating the first-order magnetization rising curve or the first-order magnetization falling curve for the first time; Step S5, removing the magnetizing current or the demagnetizing current to move the second magnetization state point along the first-order magnetization rising curve or the first-order magnetization falling curve after the first update; Step S6: determining a third magnetization state point after the second magnetization state point moves at the current moment, updating the first-order magnetization rising curve or the first-order magnetization falling curve for the second time, and retaining the third magnetization state point for calculating motor parameters.

2. The variable flux memory motor design method according to claim 1, characterized in that: Before executing step S1, the method further includes: The main magnetization curve and the main demagnetization curve are connected end to end to form a closed area to obtain two curve connection points, and the curve connection point located in the first quadrant is used as the connection point corresponding to the positive maximum value, and the curve connection point located in the fourth quadrant is used as the connection point corresponding to the reverse maximum value.

3. The variable flux memory motor design method according to claim 2, characterized in that: Before executing step S1, the main demagnetization curve is defined as: When the first magnetization state point is demagnetized at the positive maximum value, the first magnetization state point moves along the main demagnetization curve.

4. The variable flux memory motor design method according to claim 2, characterized in that: Before executing step S1, the main magnetization curve is defined as: When the first magnetization state point is magnetized at the reverse maximum value, the first magnetization state point moves along the main magnetization curve.

5. The variable flux memory motor design method according to claim 1, characterized in that: Before executing step S1, each of the first-order magnetization rising curves is defined as a family of curves showing changes in the first magnetization state point and the second magnetization state point during magnetization.

6. The variable flux memory motor design method according to claim 1, characterized in that: Before executing step S1, each of the first-order magnetization decline curves is defined as a family of curves showing changes in the first magnetization state point and the second magnetization state point during demagnetization.

7. The variable flux memory motor design method according to claim 1, characterized in that: The variable flux memory motor design method further includes a motor parameter calculation process, which includes: Step A1: Determine whether the variable flux memory motor needs to expand its speed range: If yes, go to step S1 and go to step A2 after obtaining the third magnetization state point; If not, return to step A1; Step A2: Calculate the corresponding motor parameters according to the third magnetization state point and the magnetic field strength at the current moment.

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