Methods, devices, and media for determining the composite load torque range of two-phase short-circuit protection

Abstract

This invention belongs to the field of permanent magnet motor protection technology, and relates to a method, device, and medium for determining the composite load torque range for two-phase short circuit protection. A composite load coordinate system is constructed. Based on the fact that the horizontal coordinate of the first vertex is 0, and the relationship between the vertical coordinate and the speed, inductance, and resistance of the permanent magnet motor is a ternary linear fitting equation, the coordinates of the first vertex are calculated. Based on the fact that the horizontal and vertical coordinates of the second vertex both exhibit a multivariate nonlinear fitting equation with respect to the speed, inductance, and resistance of the permanent magnet motor, the coordinates of the second vertex are calculated. A first line segment between the first vertex and the origin is obtained, and a first ray passing through the first vertex with a slope of 1 is constructed. A second ray passing through the second vertex with a slope of 1 is constructed, and a third ray passing through the second vertex with a slope of -1 is constructed. The intersection point of the third ray with the horizontal axis is obtained, and the second line segment between the intersection point and the origin is obtained, thereby obtaining the composite load torque range using two-phase short circuit protection.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor protection technology, and in particular to a method, apparatus, and computer-readable storage medium for determining the composite load torque range of two-phase short circuit protection. Background Technology

[0002] Permanent magnet motors are widely used in various industrial fields due to their high efficiency and high torque density. However, the use of permanent magnet materials brings the risk of irreversible demagnetization to permanent magnet motors, which leads to a gradual decline in motor performance. If a permanent magnet motor wants to achieve the output torque before demagnetization, it needs a larger winding current, which may cause the winding temperature to rise and damage the insulation. The sealing of commercial permanent magnet motors also makes it difficult to replace demagnetized permanent magnets. Manufacturing a new permanent magnet will also increase costs. Therefore, how to reduce the impact of irreversible demagnetization on the long-term reliability of permanent magnet motors is an urgent problem to be solved.

[0003] A short-circuit fault in the drive system leads to a rapid increase in short-circuit current, which in turn generates a strong demagnetizing magnetic field. This is one of the main causes of irreversible demagnetization. Therefore, short-circuit protection for permanent magnet motors can effectively reduce the risk of irreversible demagnetization. Existing technologies propose two protection strategies: forced transition to single-phase short-circuit or three-phase short-circuit protection. Figure 1 As shown, when a short circuit occurs in the permanent magnet motor at a rotor speed of 500 rpm, the peak short-circuit current under single-phase short-circuit protection is 28.44 A, and the peak short-circuit current under three-phase short-circuit protection is 25.86 A, a difference of 2.58 A. Figure 2 As shown, when a short circuit occurs in a permanent magnet motor at a rotor speed of 5000 rpm, the peak short-circuit current under single-phase short-circuit protection is 51.42 A, while the peak short-circuit current under three-phase short-circuit protection is 25.86 A, a difference of 25.56 A. The peak short-circuit current of a single-phase motor is almost twice that of a three-phase short-circuit motor, which would cause more severe demagnetization than a three-phase short circuit. However, these comparative data are based on the assumption that the moment of inertia of the permanent magnet motor is infinite and its speed is constant. In actual operation, the current distortion during a short circuit in a permanent magnet motor leads to electromagnetic torque distortion, which in turn causes a change in motor speed. This change in speed affects the short-circuit current, which is very different from the short-circuit current under constant speed. Therefore, choosing a single-phase or three-phase short-circuit protection strategy based on the constant speed assumption is inconsistent with actual operating conditions and may even exacerbate the short-circuit current, increasing the risk of irreversible demagnetization.

[0004] In summary, existing short-circuit protection methods for permanent magnet motors, which select single-phase or three-phase short-circuit protection strategies based on the constant speed assumption, ignore the fact that the actual operating speed of a permanent magnet motor is difficult to keep constant. This makes it difficult for the selected short-circuit protection strategy to effectively reduce the short-circuit current and cannot effectively mitigate the risk of irreversible demagnetization. Summary of the Invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the problem that the short circuit protection method of permanent magnet motor based on the constant speed assumption and selecting single-phase short circuit protection or three-phase short circuit protection strategy ignores the fact that the speed of permanent magnet motor is difficult to keep constant during actual operation, which makes it difficult for the selected short circuit protection strategy to effectively reduce the short circuit current and cannot effectively mitigate the risk of irreversible demagnetization.

[0006] To solve the above-mentioned technical problems, the present invention provides a method for determining the composite load torque range of two-phase short-circuit protection, comprising:

[0007] A composite load coordinate system is constructed with the amplitude of the load torque having resistance properties as the horizontal axis and the amplitude of the load torque having gravity properties as the vertical axis.

[0008] The abscissa of the first vertex of the composite load torque range based on two-phase short-circuit protection is 0, and the ordinate is related to the speed, inductance and resistance of the permanent magnet motor by a ternary linear fitting equation. Calculate the coordinates of the first vertex.

[0009] The abscissa and ordinate of the second vertex of the composite load torque range based on two-phase short-circuit protection are related to the speed, inductance and resistance of the permanent magnet motor by a multivariate nonlinear fitting equation. The coordinates of the second vertex are calculated.

[0010] Obtain the first line segment between the first vertex and the origin of the composite load coordinate system, and construct the first ray passing through the first vertex with a slope of 1;

[0011] Construct a second ray passing through the second vertex with a slope of 1, construct a third ray passing through the second vertex with a slope of -1, obtain the intersection point of the third ray with the horizontal axis of the composite load coordinate system, and obtain the second line segment between the intersection point and the origin of the composite load coordinate system.

[0012] Based on the first region formed by the first ray, the second ray, and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment, and the third ray in the composite load coordinate system, the composite load torque range utilizing two-phase short-circuit protection is obtained.

[0013] Preferably, the formula for calculating the coordinates of the first vertex is:

[0014] ,

[0015] ,

[0016] in, Represents the x-coordinate of the first vertex; Represents the y-coordinate of the first vertex; , , , The fitting parameters represent the ternary linear equation. Indicates the rotational speed of the permanent magnet motor; Indicates the inductance of a permanent magnet motor; This indicates the resistance of the permanent magnet motor.

[0017] Preferably, when the permanent magnet motor is an SPM motor, The value range is 10.2 ± 10.2 * 5%. The value range is 0.0015 ± 0.0015 * 5%. The value range is -0.85 ± 0.85 * 5%. The value range is -2 ± 2*5%;

[0018] When the permanent magnet motor is an IPM motor The value range is 11.6 ± 11.6 * 5%. The value range is 0.0018 ± 0.0018 * 5%. The value range is -1.12 ± 1.12 * 5%. The value range is -2.35 ± 2.35 * 5%.

[0019] Preferably, the formula for calculating the coordinates of the second vertex is:

[0020] ,

[0021] ,

[0022] in, Represents the x-coordinate of the second vertex; Represents the ordinate of the second vertex; , , , , , , The fitting parameters of the multivariate nonlinear fitting equation corresponding to the x-coordinate of the second vertex are represented. Indicates the rotational speed of the permanent magnet motor; Indicates the inductance of a permanent magnet motor; This indicates the resistance of the permanent magnet motor; This represents the rotor inertia of a permanent magnet motor. , , , , , , The fitting parameters represent the multivariate nonlinear fitting equation corresponding to the ordinate of the second vertex.

[0023] Preferably, when the permanent magnet motor is an SPM motor, The value range is -14.5 ± 14.5 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value range is 1 ± 1*5%. The value range is 10 ± 10 * 5%. The value range is 0.05 ± 0.05 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value range is -0.5 ± 0.5 * 5%;

[0024] When the permanent magnet motor is an IPM motor The value range is -12 ± 12 * 5%. The value range is 0.0004 ± 0.0004 * 5%. The value range is 1.2 ± 1.2 * 5%. The value range is 11.5 ± 11.5 * 5%. The value range is 0.058 ± 0.058 * 5%. The value range is 0.0006 ± 0.0006 * 5%. The value of is 0;

[0025] When the permanent magnet motor is an SPM motor The value range is 2.25 ± 2.25 * 5%. The value range is 0.0025 ± 0.0025 * 5%. The value range is -0.5 ± 0.5 * 5%. The value of is 0. The value range is -0.15 ± 0.15 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value of is 0;

[0026] When the permanent magnet motor is an IPM motor The value range is 2 ± 2 * 5%. The value range is 0.002 ± 0.002 * 5%. The value range is -0.58 ± 0.58 * 5%. The value of is 0. The value range is -0.17 ± 0.17 * 5%. The value range is 0.0006 ± 0.0006 * 5%. The value of is 0.

[0027] Preferably, obtaining the composite load torque range utilizing two-phase short-circuit protection based on the first region and the second region includes:

[0028] Based on the horizontal and vertical coordinates of each point in the first and second regions, the load torque amplitude with resistance properties and the load torque amplitude with gravity properties are obtained for each point.

[0029] Based on the load torque amplitudes with resistance properties at all points in the first and second regions, a first load torque amplitude range is obtained; based on the load torque amplitudes with gravity properties at all points in the first and second regions, a second load torque amplitude range is obtained.

[0030] Based on the first load torque amplitude range and the second load torque amplitude range, the composite load torque range utilizing two-phase short-circuit protection is obtained.

[0031] Preferably, after obtaining the composite load torque range utilizing two-phase short-circuit protection, the method further includes:

[0032] Real-time monitoring of the torque amplitude of the permanent magnet motor under both resistance and gravity loads;

[0033] When the amplitude of the load torque with resistance characteristics of the permanent magnet motor is within the first load torque amplitude range, and the amplitude of the load torque with gravity characteristics of the permanent magnet motor is within the second load torque amplitude range, the permanent magnet motor is protected by a two-phase short circuit.

[0034] Preferably, when the amplitude of the load torque of the permanent magnet motor with resistance characteristics is not within the first load torque amplitude range and / or the amplitude of the load torque of the permanent magnet motor with gravity characteristics is not within the second load torque amplitude range, the permanent magnet motor is protected by a three-phase short circuit.

[0035] The present invention also provides a composite load torque range determination device for two-phase short-circuit protection, comprising:

[0036] The coordinate system construction module is used to construct a composite load coordinate system with the magnitude of the load torque having resistance properties as the horizontal axis and the magnitude of the load torque having gravity properties as the vertical axis.

[0037] The first vertex coordinate calculation module is used to calculate the coordinates of the first vertex based on the composite load torque range of two-phase short-circuit protection, where the abscissa is 0 and the ordinate is related to the speed, inductance and resistance of the permanent magnet motor by a ternary linear fitting equation.

[0038] The second vertex coordinate calculation module is used to calculate the coordinates of the second vertex based on the abscissa and ordinate of the second vertex in the composite load torque range based on two-phase short-circuit protection. The relationship between the second vertex and the speed, inductance and resistance of the permanent magnet motor is a multivariate nonlinear fitting equation.

[0039] The first line segment and ray construction module is used to obtain the first line segment between the first vertex and the origin of the composite load coordinate system, and to construct the first ray that passes through the first vertex and has a slope of 1.

[0040] The second line segment and ray construction module is used to construct a second ray passing through the second vertex with a slope of 1, construct a third ray passing through the second vertex with a slope of -1, obtain the intersection point of the third ray with the horizontal axis of the composite load coordinate system, and obtain the second line segment between the intersection point and the origin of the composite load coordinate system.

[0041] The interval determination module is used to obtain the composite load torque interval using two-phase short-circuit protection based on the first region formed by the first ray, the second ray and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment and the third ray in the composite load coordinate system.

[0042] The present invention also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the above-described method for determining the composite load torque range of two-phase short-circuit protection.

[0043] The method for determining the composite load torque range of two-phase short-circuit protection provided in this application has the following advantages:

[0044] Since the speed of a permanent magnet motor changes due to a short circuit, the motor speed and current during the short circuit process largely depend on the load characteristics. Based on this, this application, through experimental analysis, found that the peak short-circuit current of two-phase short-circuit protection is lower than that of three-phase short-circuit protection in some cases. Therefore, this application considers using a two-phase short-circuit protection strategy to protect the permanent magnet motor. Furthermore, this application, through experimental data fitting, found that when constructing a composite load torque coordinate system with load torque having resistance characteristics as the abscissa and load torque having gravity characteristics as the ordinate, there are two vertex coordinates in the composite load torque range of the two-phase short-circuit protection. One vertex has an abscissa that is always equal to 0, and its ordinate has a ternary linear relationship with the speed, inductance, and resistance of the permanent magnet motor. The second vertex has both abscissa and ordinate that have a multivariate nonlinear relationship with the speed, inductance, and resistance of the permanent magnet motor. Therefore, this application directly calculates the coordinates of the two vertices in the composite load torque coordinate system and, based on various... By constructing line segments and rays with slopes of 1 or -1 from the vertices and the origin, the load torque range suitable for the two-phase short-circuit protection strategy of the permanent magnet motor can be quickly and accurately determined based on the area enclosed by each line segment and ray. When the load torque values ​​of the permanent magnet motor with resistance and those with gravity are both within this range, the two-phase short-circuit protection strategy can minimize the peak short-circuit current and achieve the optimal protection effect. Since this application is based on the range determination method constructed under the condition that the motor speed changes due to the short circuit, it avoids the problem that the existing technology cannot effectively reduce the peak short-circuit current by selecting single-phase or three-phase short-circuit protection strategies based on the constant speed assumption. At the same time, it does not require a large number of parameterized scans. It is only necessary to determine whether the two-phase short-circuit protection strategy can minimize the peak short-circuit current under the current operating state based on the load torque amplitude of the permanent magnet motor. Thus, the optimal short-circuit protection strategy corresponding to various load characteristics can be quickly determined, effectively preventing the short-circuit current of the permanent magnet motor from increasing sharply. Attached Figure Description

[0045] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0046] Figure 1 A schematic diagram of the current under single-phase short circuit and three-phase short circuit protection when the speed of the permanent magnet motor provided in this application is 500 rpm;

[0047] Figure 2 A schematic diagram of the current under single-phase short circuit and three-phase short circuit protection when the speed of the permanent magnet motor provided in this application is 5000 rpm;

[0048] Figure 3 A schematic diagram of the torque-speed curve of the potential energy constant torque load of the permanent magnet motor provided in this application;

[0049] Figure 4 A schematic diagram of the torque-speed curve of the permanent magnet motor with a resistive constant torque load provided in this application;

[0050] Figure 5 A schematic diagram of the two-phase short-circuit topology of the permanent magnet motor provided in this application;

[0051] Figure 6 The diagram shows the current under single-phase short circuit, two-phase short circuit, and three-phase short circuit protection when the speed of the permanent magnet motor provided in this application is 500 rpm, the GLT is 5 Nm, and the total inertia is 10 times the rotor inertia.

[0052] Figure 7 The diagram shows the current under single-phase short circuit, two-phase short circuit, and three-phase short circuit protection when the speed of the permanent magnet motor provided in this application is 700 rpm, the GLT is 5 Nm, and the total inertia is 10 times the rotor inertia.

[0053] Figure 8 The trend of short-circuit peak current of the single-phase short-circuit protection under potential energy constant speed load provided in this application as a function of load torque and total inertia;

[0054] Figure 9 The trend of short-circuit peak current of the three-phase short-circuit protection under potential energy constant speed load provided in this application as a function of load torque and total inertia;

[0055] Figure 10 Flowchart of the method for determining the composite load torque range of two-phase short-circuit protection provided in this application;

[0056] Figure 11 A schematic diagram of the composite load coordinate system constructed for embodiments of this application;

[0057] Figure 12 A schematic diagram of the first line segment and the first ray constructed for embodiments of this application;

[0058] Figure 13 A schematic diagram of the second line segment, second ray, and third ray constructed for embodiments of this application;

[0059] Figure 14 This is a schematic diagram of the composite load torque range obtained in an embodiment of this application;

[0060] Figure 15 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.005 mH, and a resistance of 0.4 Ω, as obtained in the experiments of this application. Figure 15 In (a), the total inertia is 20 Jr. Figure 15 In (b), the total inertia is 30 Jr. Figure 15 In the figure (c), the total inertia is 40 Jr. Figure 15 In this context, (d) represents a total inertia of 50Jr;

[0061] Figure 16 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.004 mH, and a resistance of 0.4 Ω, as obtained in the experiments of this application. Figure 16 In (a), the total inertia is 20 Jr. Figure 16 In (b), the total inertia is 30 Jr. Figure 16 In the figure (c), the total inertia is 40 Jr. Figure 16 In this context, (d) represents a total inertia of 50Jr;

[0062] Figure 17 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.006 mH, and a resistance of 0.4 Ω, as obtained in the experiments of this application. Figure 17 In (a), the total inertia is 20 Jr. Figure 17 In (b), the total inertia is 30 Jr. Figure 17 In the figure (c), the total inertia is 40 Jr. Figure 17 In this context, (d) represents a total inertia of 50Jr;

[0063] Figure 18 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.005 mH, and a resistance of 0.3 Ω, as obtained in the experiments of this application. Figure 18 In (a), the total inertia is 20 Jr. Figure 18 In (b), the total inertia is 30 Jr. Figure 18 In the figure (c), the total inertia is 40 Jr. Figure 18 In this context, (d) represents a total inertia of 50Jr;

[0064] Figure 19 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.005 mH, and a resistance of 0.5 Ω, as obtained in the experiments of this application. Figure 19 In (a), the total inertia is 20 Jr. Figure 19 In (b), the total inertia is 30 Jr. Figure 19 In the figure (c), the total inertia is 40 Jr. Figure 19 In this context, (d) represents a total inertia of 50Jr;

[0065] Figure 20 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 600 rpm, an inductance of 0.005 mH, and a resistance of 0.4 Ω, as obtained in the experiments of this application. Figure 20 In (a), the total inertia is 20 Jr. Figure 20 In (b), the total inertia is 30 Jr. Figure 20 In the figure (c), the total inertia is 40 Jr. Figure 20 In this context, (d) represents a total inertia of 50Jr;

[0066] Figure 21 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 700 rpm, an inductance of 0.005 mH, and a resistance of 0.4 Ω, as obtained in the experiments of this application. Figure 21 In (a), the total inertia is 20 Jr. Figure 21 In (b), the total inertia is 30 Jr. Figure 21 (c) in the figure represents a total inertia of 40Jr;

[0067] Figure 22 This diagram illustrates the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 700 rpm, an inductance of 0.006 mH, and a resistance of 0.7 Ω, as obtained in the experiments of this application. Figure 22 In (a), the total inertia is 20 Jr. Figure 22 In (b), the total inertia is 30 Jr. Figure 22 In the figure (c), the total inertia is 40 Jr. Figure 22 In the figure, (d) represents a total inertia of 50Jr. Detailed Implementation

[0068] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0069] When the speed of a permanent magnet motor changes due to a short circuit, the motor speed and current during the short circuit process largely depend on the load characteristics. Common load types for permanent magnet motors include potential energy constant torque loads (GLT) and reactive constant torque loads (DFT), and their torque-speed curves are as follows: Figure 3 and Figure 4 As shown. When considering load characteristics, strategies that prioritize two-phase short-circuit protection are rarely chosen, such as... Figure 5The diagram shows a two-phase circuit topology. This application finds that in practical applications, compared to single-phase and three-phase short circuits, a two-phase short circuit may result in a smaller peak short-circuit current, such as... Figure 6 As shown, when the permanent magnet motor speed is 500 rpm, the GLT is 5 Nm, and the total inertia is 10 times the rotor inertia (10Jr), the short-circuit peak current under three-phase short-circuit protection is the smallest, at 19.26 A, the short-circuit peak current under two-phase short-circuit protection is 19.78 A, and the short-circuit peak current under single-phase short-circuit protection is 29.5 A. At this point, three-phase short-circuit protection is the most suitable short-circuit protection strategy for the permanent magnet motor. However, when the speed increases to 700 rpm, as... Figure 7 As shown, the peak short-circuit current under three-phase short-circuit protection is 23.89A, the peak short-circuit current under two-phase short-circuit protection is 23.32A, and the peak short-circuit current under single-phase short-circuit protection is 29.47A. Obviously, two-phase short-circuit protection should be the best protection strategy at this time.

[0070] Existing technologies also propose a method for determining short-circuit protection strategies for permanent magnet motors that considers load characteristics, such as... Figure 8 and Figure 9 As shown, under both potential energy constant torque load and resistive constant torque load, the load torque is divided into several equally spaced intervals. The permanent magnet motor is switched to single-phase short-circuit and three-phase short-circuit operation, respectively. Within different load torque intervals, the peak short-circuit current under two short-circuit protection conditions is calculated for different inertia intervals, thereby determining the short-circuit protection strategy for each load characteristic. However, this method does not consider two-phase short-circuit protection strategies. Furthermore, this method of determining the protection strategy through parameterized scanning of load torque and total inertia is labor-intensive and inefficient.

[0071] Since the peak short-circuit current of two-phase short-circuit protection is lower than that of three-phase short-circuit protection in some cases, this application proposes a method for determining the composite load torque range of two-phase short-circuit protection while considering the use of two-phase short-circuit protection strategy to protect permanent magnet motors. This eliminates the need for extensive parameterization scanning; it only requires determining whether the two-phase short-circuit protection strategy can minimize the peak short-circuit current under the current operating conditions based on the load torque amplitude of the permanent magnet motor. This allows for the rapid determination of the optimal short-circuit protection strategy corresponding to various load characteristics.

[0072] Please see Figure 10 , Figure 10 The flowchart shown is a method for determining the composite load torque range of two-phase short-circuit protection provided in this application. The method specifically includes S10~S60:

[0073] S10: Construct a composite load coordinate system with the amplitude of the load torque having resistance properties as the horizontal axis and the amplitude of the load torque having gravity properties as the vertical axis.

[0074] S20: The abscissa of the first vertex of the composite load torque range based on two-phase short-circuit protection is 0, and the ordinate is related to the speed, inductance and resistance of the permanent magnet motor by a ternary linear fitting equation. Calculate the coordinates of the first vertex.

[0075] S30: The abscissa and ordinate of the second vertex of the composite load torque range based on two-phase short-circuit protection are both related to the speed, inductance and resistance of the permanent magnet motor by a multivariate nonlinear fitting equation. Calculate the coordinates of the second vertex.

[0076] S40: Obtain the first line segment between the first vertex and the origin of the composite load coordinate system, and construct the first ray passing through the first vertex with a slope of 1.

[0077] S50: Construct a second ray passing through the second vertex with a slope of 1, construct a third ray passing through the second vertex with a slope of -1, obtain the intersection point of the third ray with the horizontal axis of the composite load coordinate system, and obtain the second line segment between the intersection point and the origin of the composite load coordinate system.

[0078] S60: Based on the first region formed by the first ray, the second ray, and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment, and the third ray in the composite load coordinate system, obtain the composite load torque range using two-phase short-circuit protection.

[0079] Specifically, the formula for calculating the coordinates of the first vertex is:

[0080] ,

[0081] ,

[0082] in, Represents the x-coordinate of the first vertex; Represents the y-coordinate of the first vertex; , , , The fitting parameters represent the ternary linear equation. Indicates the rotational speed of the permanent magnet motor; Indicates the inductance of a permanent magnet motor; This indicates the resistance of the permanent magnet motor.

[0083] Specifically, when the permanent magnet motor is an SPM motor, The value range is 10.2 ± 10.2 * 5%. The value range is 0.0015 ± 0.0015 * 5%. The value range is -0.85 ± 0.85 * 5%. The value range is -2 ± 2*5%.

[0084] When the permanent magnet motor is an IPM motor The value range is 11.6 ± 11.6 * 5%. The value range is 0.0018 ± 0.0018 * 5%. The value range is -1.12 ± 1.12 * 5%. The value range is -2.35 ± 2.35 * 5%.

[0085] For example, the optimal values ​​of the fitting parameters for the ternary linear equations are shown in Table 1 for different types of permanent magnet motors:

[0086] Table 1

[0087]

[0088] Specifically, the formula for calculating the coordinates of the second vertex is:

[0089] ,

[0090] ,

[0091] in, Represents the x-coordinate of the second vertex; Represents the ordinate of the second vertex; , , , , , , The fitting parameters of the multivariate nonlinear fitting equation corresponding to the x-coordinate of the second vertex are represented. Indicates the rotational speed of the permanent magnet motor; Indicates the inductance of a permanent magnet motor; This indicates the resistance of the permanent magnet motor; This represents the rotor inertia of a permanent magnet motor. , , , , , , The fitting parameters represent the multivariate nonlinear fitting equation corresponding to the ordinate of the second vertex.

[0092] Specifically, when the permanent magnet motor is an SPM motor, The value range is -14.5 ± 14.5 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value range is 1 ± 1*5%. The value range is 10 ± 10 * 5%. The value range is 0.05 ± 0.05 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value range is -0.5 ± 0.5 * 5%.

[0093] When the permanent magnet motor is an IPM motor The value range is -12 ± 12 * 5%. The value range is 0.0004 ± 0.0004 * 5%. The value range is 1.2 ± 1.2 * 5%. The value range is 11.5 ± 11.5 * 5%. The value range is 0.058 ± 0.058 * 5%. The value range is 0.0006 ± 0.0006 * 5%. The value of is 0.

[0094] When the permanent magnet motor is an SPM motor The value range is 2.25 ± 2.25 * 5%. The value range is 0.0025 ± 0.0025 * 5%. The value range is -0.5 ± 0.5 * 5%. The value of is 0. The value range is -0.15 ± 0.15 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value of is 0.

[0095] When the permanent magnet motor is an IPM motor The value range is 2 ± 2 * 5%. The value range is 0.002 ± 0.002 * 5%. The value range is -0.58 ± 0.58 * 5%. The value of is 0. The value range is -0.17 ± 0.17 * 5%. The value range is 0.0006 ± 0.0006 * 5%. The value of is 0.

[0096] For example, the optimal values ​​of the fitting parameters for the multivariate nonlinear fitting equations for different types of permanent magnet motors are shown in Table 2:

[0097] Table 2

[0098]

[0099] Furthermore, based on the first and second regions, the composite load torque range utilizing two-phase short-circuit protection is obtained, including S600~S602:

[0100] S600: Based on the horizontal and vertical coordinates of each point in the first and second regions, obtain the load torque amplitude with resistance properties and the load torque amplitude with gravity properties at each point.

[0101] S601: Based on the load torque amplitude with resistance properties at all points in the first and second regions, a first load torque amplitude range is obtained; based on the load torque amplitude with gravity properties at all points in the first and second regions, a second load torque amplitude range is obtained.

[0102] S602: Based on the first load torque amplitude range and the second load torque amplitude range, the composite load torque range utilizing two-phase short-circuit protection is obtained.

[0103] Furthermore, after obtaining the composite load torque range utilizing two-phase short-circuit protection, it also includes S70~S80:

[0104] S70: Real-time monitoring of the amplitude of the load torque with resistance characteristics and the amplitude of the load torque with gravity characteristics of the permanent magnet motor.

[0105] S80: When the amplitude of the load torque of the permanent magnet motor with resistance characteristics is within the first load torque amplitude range, and the amplitude of the load torque of the permanent magnet motor with gravity characteristics is within the second load torque amplitude range, the permanent magnet motor is protected by a two-phase short circuit.

[0106] Specifically, when the amplitude of the load torque of the permanent magnet motor with resistance characteristics is not within the first load torque amplitude range and / or the amplitude of the load torque of the permanent magnet motor with gravity characteristics is not within the second load torque amplitude range, the permanent magnet motor is protected by a three-phase short circuit.

[0107] The above method will be further explained and illustrated below through a specific embodiment. This embodiment takes an SPM permanent magnet motor as an example, with a rotational speed of... ,inductance ,resistance The total inertia is 30Jr. The method for determining the composite load torque range of the two-phase short-circuit protection includes steps 1 to 4:

[0108] Step 1: Construct a composite load coordinate system, such as Figure 11As shown, the origin is denoted as O, the horizontal axis represents the torque amplitude of the load with resistance properties, i.e., the potential energy constant torque load is taken as the horizontal axis, and the vertical axis represents the torque amplitude of the load with gravity properties, i.e., the resistance constant torque load is taken as the vertical axis.

[0109] Step 2: Calculate the first vertex of the SPM motor according to the first vertex coordinate formula:

[0110] ,

[0111] ,

[0112] The coordinates of the first vertex are (0, 6). Obtain the first line segment between the first vertex and the origin of the composite load coordinate system. Construct the first ray passing through the first vertex with a slope of 1, as follows: Figure 12 As shown.

[0113] Step 3: Calculate the second vertex of the SPM motor according to the formula for the coordinates of the second vertex:

[0114] ,

[0115] ,

[0116] The coordinates of the second vertex are (0, 4). Construct a second ray passing through the second vertex with a slope of 1. Construct a third ray passing through the second vertex with a slope of -1. Obtain the intersection point of the third ray and the x-coordinate of the composite load coordinate system. Obtain the second line segment between the intersection point and the origin of the composite load coordinate system, such as... Figure 13 As shown.

[0117] Step 4: Based on the first region formed by the first ray, the second ray, and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment, and the third ray in the composite load coordinate system, obtain the composite load torque range utilizing two-phase short-circuit protection, such as... Figure 14 The yellow area in the image.

[0118] For example, according to Figure 14 It can be seen that when the load torque amplitude with resistance properties is 3 and the load torque amplitude with gravity properties is 0, the two-phase short-circuit protection strategy can minimize the short-circuit peak current of the permanent magnet motor and achieve the optimal protection effect.

[0119] Based on the method for determining the composite load torque range of two-phase current protection provided in the above embodiments, this application also provides a device for determining the composite load torque range of two-phase current protection, which specifically includes:

[0120] The coordinate system construction module is used to construct a composite load coordinate system with the magnitude of the load torque, which has resistance properties, as the horizontal axis and the magnitude of the load torque, which has gravity properties, as the vertical axis.

[0121] The first vertex coordinate calculation module is used to calculate the coordinates of the first vertex based on the composite load torque range of two-phase short-circuit protection, where the abscissa is 0 and the ordinate is related to the speed, inductance, and resistance of the permanent magnet motor by a ternary linear fitting equation.

[0122] The second vertex coordinate calculation module is used to calculate the coordinates of the second vertex based on the abscissa and ordinate of the second vertex in the composite load torque range based on two-phase short-circuit protection. The relationship between the second vertex and the speed, inductance and resistance of the permanent magnet motor is a multivariate nonlinear fitting equation.

[0123] The first line segment and ray construction module is used to obtain the first line segment between the first vertex and the origin of the composite load coordinate system, and to construct the first ray passing through the first vertex with a slope of 1.

[0124] The second line segment and ray construction module is used to construct a second ray passing through the second vertex with a slope of 1, construct a third ray passing through the second vertex with a slope of -1, obtain the intersection point of the third ray with the horizontal axis of the composite load coordinate system, and obtain the second line segment between the intersection point and the origin of the composite load coordinate system.

[0125] The interval determination module is used to obtain the composite load torque interval using two-phase short-circuit protection based on the first region formed by the first ray, the second ray and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment and the third ray in the composite load coordinate system.

[0126] This application also provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of the above-described method for determining the composite load torque range of two-phase short-circuit protection.

[0127] It should be noted that the coordinate calculation formulas for the first and second vertices provided in this application are obtained through fitting a large amount of experimental data. Therefore, some experimental data are provided in the embodiments of this application:

[0128] Figure 15 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.005 mH, and a resistance of 0.4 Ω, obtained from the experiments of this application. Figure 15 In (a), the total inertia is 20 Jr. Figure 15 In (b), the total inertia is 30 Jr. Figure 15In the figure (c), the total inertia is 40 Jr. Figure 15 In the figure, (d) represents a total inertia of 50Jr.

[0129] Figure 16 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.004 mH, and a resistance of 0.4 Ω, obtained from the experiments of this application. Figure 16 In (a), the total inertia is 20 Jr. Figure 16 In (b), the total inertia is 30 Jr. Figure 16 In the figure (c), the total inertia is 40 Jr. Figure 16 In the figure, (d) represents a total inertia of 50Jr.

[0130] Figure 17 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.006 mH, and a resistance of 0.4 Ω, obtained from the experiments of this application. Figure 17 In (a), the total inertia is 20 Jr. Figure 17 In (b), the total inertia is 30 Jr. Figure 17 In the figure (c), the total inertia is 40 Jr. Figure 17 In the figure, (d) represents a total inertia of 50Jr.

[0131] Figure 18 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.005 mH, and a resistance of 0.3 Ω, obtained from the experiments of this application. Figure 18 In (a), the total inertia is 20 Jr. Figure 18 In (b), the total inertia is 30 Jr. Figure 18 In the figure (c), the total inertia is 40 Jr. Figure 18 In the figure, (d) represents a total inertia of 50Jr.

[0132] Figure 19 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 500 rpm, an inductance of 0.005 mH, and a resistance of 0.5 Ω, obtained from the experiments of this application. Figure 19 In (a), the total inertia is 20 Jr. Figure 19 In (b), the total inertia is 30 Jr. Figure 19 In the figure (c), the total inertia is 40 Jr. Figure 19 In the figure, (d) represents a total inertia of 50Jr.

[0133] Figure 20 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 600 rpm, an inductance of 0.005 mH, and a resistance of 0.4 Ω, obtained from the experiments of this application. Figure 20 In (a), the total inertia is 20 Jr. Figure 20 In (b), the total inertia is 30 Jr. Figure 20 In the figure (c), the total inertia is 40 Jr. Figure 20 In the figure, (d) represents a total inertia of 50Jr.

[0134] Figure 21 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 700 rpm, an inductance of 0.005 mH, and a resistance of 0.4 Ω, obtained from the experiments of this application. Figure 21 In (a), the total inertia is 20 Jr. Figure 21 In (b), the total inertia is 30 Jr. Figure 21 (c) in the figure represents a total inertia of 40Jr.

[0135] Figure 22 The diagram shows the composite load torque range with the lowest peak short-circuit current under different total inertia conditions when the SPM permanent magnet motor has a speed of 700 rpm, an inductance of 0.006 mH, and a resistance of 0.7 Ω, obtained from the experiments of this application. Figure 22 In (a), the total inertia is 20 Jr. Figure 22 In (b), the total inertia is 30 Jr. Figure 22 In the figure (c), the total inertia is 40 Jr. Figure 22 In the figure, (d) represents a total inertia of 50Jr.

[0136] It should be noted that the first vertex in each diagram is the coordinate of the bottom left corner of the blue area, for example, Figure 15 In (a) of the figure, the coordinates of the first vertex are (0,7) and the coordinates of the second vertex are the coordinates marked at the origin of the coordinate system. By fitting multiple experimental data, it was found that the coordinates of the first and second vertices have a linear or nonlinear relationship with the speed, inductance, resistance and inertia of the permanent magnet motor. Therefore, the above-mentioned formula for calculating the coordinates of the first and second vertices was obtained.

[0137] Tables 3 to 13 show the short-circuit peak current data for different inertia values ​​under single-phase short-circuit protection for SPM permanent magnet motors with a speed of 700 rpm, an inductance of 0.005 H, and a resistance of 0.4 Ω, when the load torque amplitude has different values ​​for both resistance-dependent (GLT) and gravity-dependent (DFT) characteristics.

[0138] Table 3

[0139]

[0140] Table 4

[0141]

[0142] Table 5

[0143]

[0144] Table 6

[0145]

[0146] Table 7

[0147]

[0148] Table 8

[0149]

[0150] Table 9

[0151]

[0152] Table 10

[0153]

[0154] Table 11

[0155]

[0156] Table 12

[0157]

[0158] Table 13

[0159]

[0160] Tables 14-24 show the short-circuit peak current data for different inertia values ​​under two-phase short-circuit protection for SPM permanent magnet motors with a speed of 700 rpm, an inductance of 0.005 H, and a resistance of 0.4 Ω, when the load torque amplitude has different values ​​for resistance characteristics (GLT) and gravity characteristics (DFT) under different conditions.

[0161] Table 14

[0162]

[0163] Table 15

[0164]

[0165] Table 16

[0166]

[0167] Table 17

[0168]

[0169] Table 18

[0170]

[0171] Table 19

[0172]

[0173] Table 20

[0174]

[0175] Table 21

[0176]

[0177] Table 22

[0178]

[0179] Table 23

[0180]

[0181] Table 24

[0182]

[0183] Tables 25-35 show the peak short-circuit current data for different inertia values ​​under three-phase short-circuit protection for SPM permanent magnet motors with a speed of 700 rpm, an inductance of 0.005 H, and a resistance of 0.4 Ω, when the load torque amplitude has different values ​​for drag-resistance characteristics (GLT) and gravity characteristics (DFT).

[0184] Table 25

[0185]

[0186] Table 26

[0187]

[0188] Table 27

[0189]

[0190] Table 28

[0191]

[0192] Table 29

[0193]

[0194] Table 30

[0195]

[0196] Table 31

[0197]

[0198] Table 32

[0199]

[0200] Table 33

[0201]

[0202] Table 34

[0203]

[0204] Table 35

[0205]

[0206] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for determining the composite load torque range of two-phase short-circuit protection, characterized in that, include: A composite load coordinate system is constructed with the amplitude of the load torque having resistance properties as the horizontal axis and the amplitude of the load torque having gravity properties as the vertical axis. The abscissa of the first vertex of the composite load torque range based on two-phase short-circuit protection is 0, and the ordinate is related to the speed, inductance and resistance of the permanent magnet motor by a ternary linear fitting equation. Calculate the coordinates of the first vertex. The abscissa and ordinate of the second vertex of the composite load torque range based on two-phase short-circuit protection are related to the speed, inductance and resistance of the permanent magnet motor by a multivariate nonlinear fitting equation. The coordinates of the second vertex are calculated. Obtain the first line segment between the first vertex and the origin of the composite load coordinate system, and construct the first ray passing through the first vertex with a slope of 1; Construct a second ray passing through the second vertex with a slope of 1, construct a third ray passing through the second vertex with a slope of -1, obtain the intersection point of the third ray with the horizontal axis of the composite load coordinate system, and obtain the second line segment between the intersection point and the origin of the composite load coordinate system. Based on the first region formed by the first ray, the second ray, and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment, and the third ray in the composite load coordinate system, the composite load torque range utilizing two-phase short-circuit protection is obtained.

2. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 1, characterized in that, The formula for calculating the coordinates of the first vertex is: ， ， in, Represents the x-coordinate of the first vertex; Represents the y-coordinate of the first vertex; , , , The fitting parameters represent the ternary linear equation. Indicates the rotational speed of the permanent magnet motor; Indicates the inductance of a permanent magnet motor; This indicates the resistance of the permanent magnet motor.

3. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 2, characterized in that, When the permanent magnet motor is an SPM motor The value range is 10.2 ± 10.2 * 5%. The value range is 0.0015 ± 0.0015 * 5%. The value range is -0.85 ± 0.85 * 5%. The value range is -2 ± 2*5%; When the permanent magnet motor is an IPM motor The value range is 11.6 ± 11.6 * 5%. The value range is 0.0018 ± 0.0018 * 5%. The value range is -1.12 ± 1.12 * 5%. The value range is -2.35 ± 2.35 * 5%.

4. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 1, characterized in that, The formula for calculating the coordinates of the second vertex is: ， ， in, Represents the x-coordinate of the second vertex; Represents the ordinate of the second vertex; , , , , , , The fitting parameters of the multivariate nonlinear fitting equation corresponding to the x-coordinate of the second vertex are represented. Indicates the rotational speed of the permanent magnet motor; Indicates the inductance of a permanent magnet motor; This indicates the resistance of the permanent magnet motor; This represents the rotor inertia of a permanent magnet motor. , , , , , , The fitting parameters represent the multivariate nonlinear fitting equation corresponding to the ordinate of the second vertex.

5. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 4, characterized in that, When the permanent magnet motor is an SPM motor The value range is -14.5 ± 14.5 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value range is 1 ± 1*5%. The value range is 10 ± 10 * 5%. The value range is 0.05 ± 0.05 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value range is -0.5 ± 0.5 * 5%; When the permanent magnet motor is an IPM motor The value range is -12 ± 12 * 5%. The value range is 0.0004 ± 0.0004 * 5%. The value range is 1.2 ± 1.2 * 5%. The value range is 11.5 ± 11.5 * 5%. The value range is 0.058 ± 0.058 * 5%. The value range is 0.0006 ± 0.0006 * 5%. The value of is 0; When the permanent magnet motor is an SPM motor The value range is 2.25 ± 2.25 * 5%. The value range is 0.0025 ± 0.0025 * 5%. The value range is -0.5 ± 0.5 * 5%. The value of is 0. The value range is -0.15 ± 0.15 * 5%. The value range is 0.0005 ± 0.0005 * 5%. The value of is 0; When the permanent magnet motor is an IPM motor The value range is 2 ± 2 * 5%. The value range is 0.002 ± 0.002 * 5%. The value range is -0.58 ± 0.58 * 5%. The value of is 0. The value range is -0.17 ± 0.17 * 5%. The value range is 0.0006 ± 0.0006 * 5%. The value of is 0.

6. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 1, characterized in that, The composite load torque range utilizing two-phase short-circuit protection is obtained based on the first and second regions, including: Based on the horizontal and vertical coordinates of each point in the first and second regions, the load torque amplitude with resistance properties and the load torque amplitude with gravity properties are obtained for each point. Based on the load torque amplitudes with resistance properties at all points in the first and second regions, a first load torque amplitude range is obtained; based on the load torque amplitudes with gravity properties at all points in the first and second regions, a second load torque amplitude range is obtained. Based on the first load torque amplitude range and the second load torque amplitude range, the composite load torque range utilizing two-phase short-circuit protection is obtained.

7. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 6, characterized in that, After obtaining the composite load torque range utilizing two-phase short-circuit protection, it also includes: Real-time monitoring of the torque amplitude of the permanent magnet motor under both resistance and gravity loads; When the amplitude of the load torque with resistance characteristics of the permanent magnet motor is within the first load torque amplitude range, and the amplitude of the load torque with gravity characteristics of the permanent magnet motor is within the second load torque amplitude range, the permanent magnet motor is protected by a two-phase short circuit.

8. The method for determining the composite load torque range of two-phase short-circuit protection according to claim 7, characterized in that, If the amplitude of the load torque of the permanent magnet motor with resistance characteristics is not within the first load torque amplitude range and / or the amplitude of the load torque of the permanent magnet motor with gravity characteristics is not within the second load torque amplitude range, then the permanent magnet motor is protected by a three-phase short circuit.

9. A composite load torque range determination device for two-phase short-circuit protection, characterized in that, include: The coordinate system construction module is used to construct a composite load coordinate system with the magnitude of the load torque having resistance properties as the horizontal axis and the magnitude of the load torque having gravity properties as the vertical axis. The first vertex coordinate calculation module is used to calculate the coordinates of the first vertex based on the composite load torque range of two-phase short-circuit protection, where the abscissa is 0 and the ordinate is related to the speed, inductance and resistance of the permanent magnet motor by a ternary linear fitting equation. The second vertex coordinate calculation module is used to calculate the coordinates of the second vertex based on the abscissa and ordinate of the second vertex in the composite load torque range based on two-phase short-circuit protection. The relationship between the second vertex and the speed, inductance and resistance of the permanent magnet motor is a multivariate nonlinear fitting equation. The first line segment and ray construction module is used to obtain the first line segment between the first vertex and the origin of the composite load coordinate system, and to construct the first ray that passes through the first vertex and has a slope of 1. The second line segment and ray construction module is used to construct a second ray passing through the second vertex with a slope of 1, construct a third ray passing through the second vertex with a slope of -1, obtain the intersection point of the third ray with the horizontal axis of the composite load coordinate system, and obtain the second line segment between the intersection point and the origin of the composite load coordinate system. The interval determination module is used to obtain the composite load torque interval using two-phase short-circuit protection based on the first region formed by the first ray, the second ray and the first line segment in the composite load coordinate system, and the second region formed by the first line segment, the second line segment and the third ray in the composite load coordinate system.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of the method for determining the composite load torque range of two-phase short-circuit protection as described in any one of claims 1 to 8.

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