Torque calculation method, torque calculation device, and program for permanent magnet synchronous motor

Abstract

To provide a method of calculating torque of a permanent magnet synchronous motor that is made to achieve higher accuracy of calculation than conventional methods.SOLUTION: A method of calculating torque of a permanent magnet synchronous motor comprises: a first calculation step of calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor using a FP (Frozen Permeability) method; and a second calculation step of calculating torque of the permanent magnet synchronous motor using the calculated flux and magnetic energy, and a formula obtained by stabilizing each of magnet torque, cogging torque, and reluctance torque based on the energy conservation law.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a torque calculation method, a torque calculation device, and a program for a permanent magnet synchronous motor. [Background technology]

[0002] Motors have traditionally been used in a variety of devices. There are various types of motors, including permanent magnet synchronous motors (PM motors). PM motors are compact and highly efficient, and are therefore used as power sources for electric actuators. Motor-induced torque pulsation is one of the causes of impairing the smooth operation of electric actuators. One method for suppressing torque pulsation is torque pulsation suppression control, which suppresses torque pulsation by controlling harmonics superimposed on the motor current. Figure 7 shows the schematic configuration of a PM motor control device 700 capable of torque pulsation suppression control. In the control device 700, a harmonic current converter 702 generates current harmonic command values ​​for suppressing torque pulsation. Here, the harmonic current converter 702 receives the torque command value and the rotor rotation angle as inputs and calculates the amplitude and phase of the harmonic current based on the relationship between current and torque. Because the accuracy of the calculation of the relationship between the amplitude and phase of the harmonic current is directly related to the torque pulsation suppression effect, a highly accurate torque calculation method is required.

[0003] For example, Patent Document 1 discloses a method for calculating motor torque by using a torque equation formulated based on the law of conservation of energy and magnetic flux, inductance, and cogging torque obtained by magnetic field analysis or actual measurement. Patent Document 2 also discloses a method for calculating torque by dividing it into magnet torque and reluctance torque in order to improve motor controllability. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-57217 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-29375 Summary of the Invention [Problem to be solved by the invention]

[0005] The method of Patent Document 1 uses a linear approximation of the core magnetic characteristics, which are essentially nonlinear characteristics, and does not take into account the current dependency of magnetic flux or magnetic energy. Furthermore, the method of Patent Document 2 only takes into account the cross product term of current and magnetic flux for magnet torque and reluctance torque, and does not consider cogging torque. For these reasons, the methods of each patent document have room for improvement in terms of torque calculation accuracy.

[0006] In view of the above-mentioned problems, an object of the present invention is to provide a method for calculating torque of a permanent magnet synchronous motor with improved accuracy compared to conventional methods. [Means for solving the problem]

[0007] In order to solve the above problems, the present invention has the following configuration: That is, a torque calculation method for calculating torque of a permanent magnet synchronous motor, comprising: a first calculation step of calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step of calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; It has.

[0008] Another aspect of the present invention has the following configuration: A torque calculation device for calculating torque of a permanent magnet synchronous motor, comprising: a first calculation means for calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation means for calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; It has.

[0009] Another aspect of the present invention has the following configuration: a first calculation step of calculating magnetic flux and magnetic energy in a permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step of calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; A program for executing the above is provided. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for calculating the torque of a permanent magnet synchronous motor with improved accuracy compared to conventional methods. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram showing an example of a device configuration capable of executing a torque calculation method according to an embodiment of the present invention; [Figure 2] 4 is a flowchart of a process using a torque calculation method according to an embodiment of the present invention. [Figure 3A] 1 is a diagram showing a schematic configuration of a permanent magnet synchronous motor to which a torque calculation method according to an embodiment of the present invention can be applied; [Figure 3B] 1 is a diagram showing a schematic configuration of a permanent magnet synchronous motor to which a torque calculation method according to an embodiment of the present invention can be applied; [Figure 4A] FIG. 3 is a graph illustrating torque components of a motor A according to an embodiment of the present invention. [Figure 4B]FIG. 3 is a graph illustrating torque components of a motor A according to an embodiment of the present invention. [Figure 4C] FIG. 4 is a graph illustrating torque components of a motor B according to an embodiment of the present invention. [Figure 5A] FIG. 4 is a graph illustrating the magnet torque of each motor according to the embodiment of the present invention. [Figure 5B] FIG. 4 is a graph illustrating the reluctance torque of each motor according to the embodiment of the present invention. [Figure 5C] FIG. 4 is a graph illustrating the cogging torque of each motor according to the embodiment of the present invention. [Figure 6A] FIG. 10 is a graph illustrating the results of a comparison between a method according to an embodiment of the present invention and a conventional method using a motor A. [Figure 6B] FIG. 10 is a graph illustrating the results of a comparison between a method according to an embodiment of the present invention and a conventional method using a motor A. [Figure 6C] FIG. 10 is a graph illustrating the results of a comparison between a method according to an embodiment of the present invention and a conventional method using a motor B. [Figure 7] FIG. 1 is a block diagram showing an example of the configuration of a control device for a PM motor. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. Note that the embodiment described below is one embodiment for explaining the present invention and is not intended to be interpreted as limiting the present invention. Furthermore, not all of the configurations described in each embodiment are necessarily essential configurations for solving the problems of the present invention. Furthermore, in each drawing, the same components are assigned the same reference numerals to indicate corresponding relationships.

[0013] First Embodiment A first embodiment of the present invention will be described below. A torque calculation method for a permanent magnet synchronous motor (hereinafter also simply referred to as a "motor") according to the present invention can be used, for example, for controlling the motor, and may be used to generate a current command value from the relationship between current and torque when controlling the motor.

[0014] [Device configuration] 1 is a schematic diagram showing an example of the overall configuration of an information processing device capable of executing the calculation method according to this embodiment. The information processing device 1 according to this embodiment may be, for example, a PC (Personal Computer), and its configuration is not particularly limited. Furthermore, the information processing device 1 may be configured as an integrated device with a control device that controls the motor according to this embodiment.

[0015] The information processing device 1 includes a central processing unit (CPU) 10, a read-only memory (ROM) 11, a random access memory (RAM) 12, a hard disk drive (HDD) 13, an input device 14, a display device 15, and a communication device 16. The CPU 10 is responsible for overall control of the information processing device 1 and may implement various functions by, for example, reading and executing programs stored in the HDD 13. The ROM 11 is a non-volatile storage area. The RAM 12 is a volatile storage area used as a temporary data storage location. The HDD 13 is a non-volatile storage area in which various programs and data are stored and managed. The input device 14 is a device that accepts input from outside and includes, for example, a mouse and a keyboard. The display device 15 is a device that displays various information and includes, for example, a liquid crystal display. A touch panel display in which the input device 14 and the display device 15 are integrated may also be used. The communication device 16 is a device that communicates with an external device (not shown) via a network (not shown). The communication here may be wired or wireless, and there are no particular limitations on the communication standard.

[0016] The information processing device 1 may be configured to be able to execute a program for executing the calculation method according to this embodiment, which will be described later, as well as general-purpose electromagnetic field analysis software for performing electromagnetic field analysis. Note that the software and programs do not necessarily need to be executed by the same device that executes the torque calculation method, which will be described later. For example, the above-mentioned program may be executed by a separate device, and the processing results may then be input to the device that executes the torque calculation method according to this embodiment.

[0017] Examples of motors to which the motor calculation method of this embodiment can be applied include permanent magnet synchronous motors mounted on electric actuators, steering devices, electric brake boosters, industrial motors, etc. In addition, the method may be applied to permanent magnet synchronous motors used in general electric motors.

[0018] [Processing flow] 2 is a flowchart of a torque calculation process for calculating the torque of a motor according to this embodiment. This process is executed by the information processing device 1, for example, by the CPU 10 included in the information processing device 1 reading out from the HDD 13 and executing a program for implementing the process according to this embodiment.

[0019] In S201, the information processing device 1 applies nonlinear magnetic field analysis to the motor to be measured to obtain magnetic flux and magnetic energy, which are parameters to be used in subsequent steps. This step may be performed using general-purpose analysis software, and in this example, the analysis will be described as being performed using FEM (Finite Element Method). Details of the parameters obtained here will be described later.

[0020] In S202, the information processing device 1 calculates the magnetic fluxes ψ and φ and the magnetic energy W using the following equations (1) to (5) based on the FP (Frozen Permeability) method. Details of the FP method are well known and will not be described in this specification, but the conditions for calculation will be described later.

[0021] ψ=λ FEM [0,ψ] (1) φ=λ FEM [i,0] (2) W mp =W FEM [0,ψ] (3) W mc =W FEM [i,0] (4) W mm =W FEM [i,ψ]-W FEM [0,ψ]-W FEM [i,0] (5) ψ: Permanent magnet magnetic flux linking the coil φ: Coil magnetic flux linking the coil W mp : Magnetic energy caused by permanent magnetic flux W mc : Magnetic energy caused by coil magnetic flux W mm : Magnetic energy resulting from the interaction between the permanent magnet magnetic flux and the coil current λ FEM : Flux linkage calculated by FEM W FEM : Magnetic energy calculated by FEM

[0022] Here, in the above equation, the brackets [] indicate the conditions for the magnetomotive force source in the FP method. [0,ψ] indicates the value when the coil magnetomotive force is set to zero (0) and only the permanent magnet magnetization is considered. Similarly, [i,0] indicates the value when the permanent magnet magnetization is set to zero (0) and only the coil magnetomotive force is considered. Also, [i,ψ] indicates the value when both the permanent magnet magnetization and the coil magnetomotive force are considered simultaneously.

[0023] In S202, the information processing device 1 calculates each torque component using the following equations (6) to (8).

[0024]

number

[0025]

number

[0026]

number

[0027] τ M :Magnetic torque τ C : Cogging torque τ R : Reluctance torque p: Number of pole pairs of the motor ω: electrical angular frequency d / dt: time derivative ψ d , ψ q : Permanent magnet magnetic flux linking the coils on the d-axis and q-axis of the dq-axis coordinate system φ d , φ q : Coil magnetic flux linking the d-axis and q-axis coils of the dq-axis coordinate system i d , i q : Coil currents on the d-axis and q-axis of the dq-axis coordinate system

[0028] The d-axis and q-axis of the motor are axes in a dq-axis coordinate system. The d-axis indicates the direction of the magnetic flux of the rotor of the motor. The q-axis indicates the direction perpendicular to the d-axis.

[0029] In S204, the information processing device 1 calculates the total torque of the motor using each torque component calculated in S203 and the following equation (9). τ=τ M +τ C +τ R ···(9) τ: Total torque of the permanent magnet synchronous motor

[0030] In S205, the information processing device 1 outputs the total torque of the motor calculated in S204. The output method here is not particularly limited, and for example, the calculation result may be output on a screen, or may be output as a signal for generating a current command value related to motor control based on the relationship between current and torque. Then, this processing flow ends.

[0031] [Motor overview] 3A and 3B are diagrams showing the schematic configuration of a motor. The diagram shows the schematic configuration of a permanent magnet synchronous motor (PM motor) to which the torque calculation method according to this embodiment can be applied. Although not described here, the motor may be connected to a control device (not shown) that controls the operation of the motor, a transmission unit (not shown) that transmits the torque output by the motor, and the like. The motor may also be equipped with an inverter (not shown) for operating the PM motor, a position sensor (not shown) for detecting the position of the rotor of the motor, and the like.

[0032] FIG. 3A shows a schematic cross-sectional configuration of an example motor 300. The motor 300 includes a permanent magnet 301, a rotor core 302 (rotor), a coil 303, and a stator core 304 (stator). A plurality of permanent magnets 301 are provided along the circumference of the rotor core 302. The motor 300 has the configuration of an SPM (Surface Permanent Magnet) motor in which the permanent magnets 301 are attached to the surface of the rotor core 302, and in this example, the motor has eight magnetic poles. The coil 303 is formed of a winding or the like that generates an electromagnetic force for driving the motor 300. In this example, the winding is a concentrated winding type with 12 slots. For convenience, the motor 300 is also referred to as motor A.

[0033] FIG. 3B shows a schematic cross-sectional configuration of an example motor 310. The motor 310 includes a permanent magnet 311, a rotor core 312 (rotor), coils 313, and a stator core 314 (stator). A plurality of permanent magnets 311 are provided inside the circumferential side of the rotor core 312. The motor 310 has the configuration of an interior permanent magnet (IPM) motor in which the permanent magnets 311 are embedded inside the circumferential side of the rotor core 312, and here has eight magnetic poles. The coils 313 are formed of windings or the like that generate electromagnetic force for driving the motor 310. In this example, the windings are distributed windings with 24 slots. For convenience, the motor 310 is also referred to as motor B.

[0034] In this embodiment, an example in which the motors 300 and 310 shown in FIGS. 3A and 3B are used as an application example and the torque is calculated using the torque calculation method in the processing flow shown in FIG. 2 will be described.

[0035] 4A to 4C show examples of torque calculations for motor 300 and motor 310. In Figures 4A to 4C, the vertical axis represents torque [pu (arbitrary unit)], and the horizontal axis represents electrical angle [deg.]. In the results below, torque is normalized by its maximum value.

[0036] 4A shows a calculation example when only the fundamental component wave of current is applied to the motor 300. In this example, the current advance angle β is set to 0 [deg.] and the current amplitude is set to 50 [A] in order to utilize magnet torque as the output torque.

[0037] 4B shows a calculation example when only the fundamental component wave of current is applied to the motor 300. In this example, the current advance angle β is set to 0 [deg.] in order to utilize magnet torque as output torque, and the current amplitude is set to 100 [A], which is affected by core magnetic saturation.

[0038] 4C shows a calculation example when only the fundamental component wave of current is applied to the motor 310. In this example, the current advance angle β is set to 15 degrees and the current amplitude is set to 50 A in order to use both magnet torque and reluctance torque as the output torque.

[0039] 4A to 4C, the values ​​indicated by triangles are examples of values ​​calculated using the nodal force method, a well-known method based on nonlinear magnetic field analysis using FEM. When these values ​​are compared with the total torque calculated using the torque calculation method according to this embodiment, they match for all motors. This shows that the formulas used in the above processing flow are consistently defined.

[0040] 5A to 5C show the results of comparing examples of torque components calculated for motor 300 and motor 310. In Figures 5A to 5C, the vertical axis represents torque [pu (arbitrary unit)], and the horizontal axis represents electrical angle [deg.].

[0041] Fig. 5A shows the cross product term of magnetic flux and current, the time derivative term of magnetic flux, and the time derivative term of magnetic energy related to the magnet torque of motor 300 under the conditions of Fig. 4B. The value of the total magnet torque in Fig. 5A matches the value of the magnet torque in Fig. 4B.

[0042] Figure 5B shows the cross product term of magnetic flux and current, the time derivative term of magnetic flux, and the time derivative term of magnetic energy related to the reluctance torque of motor 310 under the conditions of Figure 4C. The value of the total reluctance torque in Figure 5B matches the value of the reluctance torque in Figure 4C.

[0043] Fig. 5C shows the current dependency of the cogging torque for each current amplitude of the motor 300. Fig. 5C also shows the cogging torque normalized by the maximum value at no load. The current amplitudes shown are 0 A, 50 A, and 100 A, respectively, and the current advance angle β is 0 degrees.

[0044] Referring to Figures 5A and 5B, it can be seen that the DC component of torque is determined only by the cross product term of magnetic flux and current, while the torque pulsation component is determined by all of the above terms. Based on this, for example, the torque calculation method of Patent Document 2, which uses only the cross product term, does not take into account the time derivative terms of magnetic flux and magnetic energy, and therefore is thought to be unable to achieve sufficient accuracy in calculating torque pulsation. Furthermore, referring to Figures 5A and 5B, since the time derivative term of magnetic energy of magnet torque contributes significantly to torque pulsation, it is thought that magnetic energy resulting from the interaction between permanent magnet magnetic flux and coil current must be taken into account in calculating magnet torque. Furthermore, as shown in Figure 5C, the amplitude and phase of cogging torque change depending on the magnitude of the current.

[0045] [Comparison with conventional methods] A comparison between this embodiment and a conventional method will be described below. Here, the conventional method is the method described in Patent Document 2. FIG. 7 shows a schematic configuration of a control device 700 used for comparison. The control device 700 includes a fundamental current converter 701, a harmonic current converter 702, and an inverter 703. The fundamental current converter 701 converts an input torque command value into a current command value. The harmonic current converter 702 derives a current harmonic command value for suppressing torque pulsation based on the input torque command value and the rotation angle of a rotor (not shown). At this time, the harmonic current converter 702 calculates the amplitude and phase of the harmonic current based on a relational expression between current and torque. The inverter 703 converts power from a power source (not shown) and supplies it to the motor based on a current command value obtained by adding the current command value from the fundamental current converter 701 and the current command value from the harmonic current converter 702. The inverter 703 may include a current control device. A part of the configuration shown in the control device 700 may be configured by a part of the information processing device 1 in FIG.

[0046] In this embodiment, a comparison result using motor A (motor 300) and motor B (motor 310) is shown. As disclosed in Patent Document 2, in the conventional method, the harmonic current conversion unit 702 performs processing using the following equation (10).

[0047]

number

[0048] L d , L q : Inductance of each of the d-axis and q-axis in the dq-axis coordinate system

[0049] 6A to 6C show examples of calculation results of the total torque of motor 300 and motor 310. In Fig. 6A to Fig. 6C, the vertical axis represents torque [pu (arbitrary unit)], and the horizontal axis represents electrical angle [deg.]. The results of the method according to this embodiment shown in Fig. 6A to Fig. 6C correspond to Fig. 4A to Fig. 4C, respectively.

[0050] 6A shows examples of calculation results using the method according to this embodiment, the conventional method, and the nodal force method when only the fundamental component wave of current is applied to the motor 300. As with FIG. 4A, this example shows a case where the current advance angle β is set to 0 [deg.] and the current amplitude is set to 50 [A] in order to utilize magnet torque as the output torque.

[0051] 6B shows examples of calculation results using the method according to this embodiment, the conventional method, and the nodal force method when only the fundamental component wave of current is applied to the motor 300. As in FIG. 4B, this example shows that the current advance angle β is set to 0 [deg.] in order to utilize magnet torque as output torque, and the current amplitude is set to 100 [A], which is affected by core magnetic saturation.

[0052] 6C shows examples of calculation results using the method according to this embodiment, the conventional method, and the nodal force method when only the fundamental component wave of current is applied to the motor 310. Here, as in FIG. 4C, this is an example in which the current advance angle β is set to 15 [deg.] and the current amplitude is set to 50 [A] in order to use both magnet torque and reluctance torque as the output torque.

[0053] The contact force method can take into account the nonlinearity of the core magnetic characteristics, magnet torque, reluctance torque, and cogging torque, and is therefore desirable for its ability to reproduce these. Referring to FIGS. 6A to 6C, the conventional method of Patent Document 2 can nearly reproduce the time-averaged torque (DC component), but cannot reproduce torque pulsation. This is because the torque equation shown in Equation (10) does not consider the time-differential term of magnetic flux, the time-differential term of magnetic energy, or cogging torque. On the other hand, referring to FIGS. 4A to 4C, 5A to 5C, and 6A to 6C, the method according to this embodiment can reproduce torque pulsation, which could not be reproduced by the conventional method, and achieves results equivalent to those of the nodal force method. In other words, the method according to this embodiment can calculate the torque of a permanent magnet synchronous motor with higher accuracy than conventional methods.

[0054] In light of the above, this embodiment uses a calculation formula that takes into account torque components whose calculation accuracy is insufficient when using methods such as those described in prior art documents. This makes it possible to calculate torque with higher accuracy than conventional methods. In particular, a calculation formula that reflects the current dependence of magnetic flux and magnetic energy using their time derivative terms allows for accurate calculation results to be obtained by taking these factors into account.

[0055] <Second embodiment> The second embodiment of the present invention will be described below, with the explanation of the configuration and the like that overlap with the first embodiment being omitted and the explanation focusing on the differences.

[0056] In the first embodiment, a two-phase coordinate system of a dq coordinate system was used as an example. In the present embodiment, a form in which torque is calculated based on values ​​in a three-phase coordinate system will be described. As the three-phase coordinate system, a uvw-axis coordinate system consisting of a u-axis, a v-axis, and a w-axis is used. Note that coordinate conversion between the two-phase coordinate system and the three-phase coordinate system may be performed by a conversion unit (not shown) included in the motor control device.

[0057] When values ​​in the three-phase coordinate system are used, the calculation formulas for the process of calculating the values ​​of each torque component (S202 in FIG. 2) are the following formulas (11) and (12) instead of formulas (6) and (8).

[0058]

number

[0059]

number

[0060] ψ u , ψ v , ψ w : Permanent magnet magnetic flux linking the coils on the u-axis, v-axis, and w-axis of the uvw-axis coordinate system φ u , φ v , φ w : Coil magnetic flux linking the coils on the u-axis, v-axis, and w-axis of the uvw-axis coordinate system i u , i v , i w : Coil currents on the u, v, and w axes of the uvw axis coordinate system

[0061] The rest of the calculation flow is the same as in the first embodiment. With this configuration, it is possible to achieve calculation accuracy equivalent to that of the first embodiment.

[0062] <Other embodiments> In addition, W included in the formula (5) shown in the above embodiment FEM The value of [i, ψ] may be replaced with magnetic energy that can be calculated by nonlinear magnetic field analysis.

[0063] In addition, in the present invention, a program or application for realizing the functions of one or more of the above-mentioned embodiments can be supplied to a system or device using a network or a storage medium, etc., and one or more processors in the computer of the system or device can read and execute the program.

[0064] Alternatively, it may be realized by a circuit that realizes one or more functions (for example, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array)).

[0065] As such, the present invention is not limited to the above-described embodiments, and the present invention also contemplates the mutual combination of the various components of the embodiments, as well as modifications and applications by those skilled in the art based on the description in the specification and well-known techniques, and these modifications and applications are included in the scope of protection sought.

[0066] As described above, the present specification discloses the following: (1) A torque calculation method for calculating torque of a permanent magnet synchronous motor, comprising: a first calculation step of calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step of calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; A torque calculation method having the following. This configuration makes it possible to provide a method for calculating the torque of a permanent magnet synchronous motor with improved accuracy compared to conventional methods.

[0067] (2) The torque calculation method according to (1), wherein the first calculation step uses the following formula based on the FP method: ψ=λ FEM [0,ψ] φ=λ FEM [i,0] W mp =W FEM [0,ψ] W mc =W FEM [i,0] W mm =W FEM[i,ψ]-W FEM [0,ψ]-W FEM [i,0] According to this configuration, it is possible to accurately calculate the torque of the permanent magnet synchronous motor using a calculation formula based on the FP method.

[0068] (3) W FEM The torque calculation method according to (2), wherein [i, ψ] is magnetic energy calculated based on the analysis results of nonlinear magnetic field analysis. According to this configuration, W is calculated using magnetic energy calculated based on the results of nonlinear magnetic field analysis. FEM It is possible to derive [i, ψ].

[0069] (4) The torque calculation method according to (2) or (3), wherein the following formula is used in the second calculation step:

[0070]

number

[0071] According to this configuration, it is possible to accurately calculate the torque of the permanent magnet synchronous motor using equations that formulate the magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy.

[0072] (5) The torque calculation method according to (2) or (3), wherein the following formula is used in the second calculation step:

[0073]

number

[0074] According to this configuration, it is possible to accurately calculate the torque of the permanent magnet synchronous motor using equations that formulate the magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy.

[0075] (6) A torque calculation device for calculating the torque of a permanent magnet synchronous motor, comprising: a first calculation means for calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation means for calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; A torque calculation device having the above structure. This configuration makes it possible to provide a method for calculating the torque of a permanent magnet synchronous motor with improved accuracy compared to conventional methods.

[0076] (7) To the computer, a first calculation step of calculating magnetic flux and magnetic energy in a permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step of calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; A program to execute. This configuration makes it possible to provide a method for calculating the torque of a permanent magnet synchronous motor with improved accuracy compared to conventional methods. [Explanation of symbols]

[0077] 1...Information processing device 10…CPU(Central Processing Unit) 11...ROM (Read Only Memory) 12…RAM(Random Access Memory) 13...HDD (Hard Disk Drive) 14...Input device 15...Display device 16...Communication equipment 300, 310...Motor 301, 311...Permanent magnets 302, 312...Rotor core 303, 313... Coil 304, 314... Stator core 700...Control device 701...Fundamental wave current conversion section 702...Harmonic current conversion section 703...Inverter

Claims

1. A torque calculation device for calculating torque of a permanent magnet synchronous motor, a first calculation means for calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation means for calculating a torque of the permanent magnet synchronous motor by using the calculated magnetic flux and magnetic energy and equations that respectively formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy, The first calculation means uses the following formula by the FP method: ψ=λ FEM [0, ψ] φ=λ FEM [i,0] W mp = W FEM [0, ψ] W mc = W FEM [i,0] W mm =W FEM [i, ψ]-W FEM [0, ψ]-W FEM [i, 0] A torque calculation device, wherein the second calculation means uses the formula [1].

2. A torque calculation device for calculating torque of a permanent magnet synchronous motor, a first calculation means for calculating magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation means for calculating a torque of the permanent magnet synchronous motor by using the calculated magnetic flux and magnetic energy and equations that respectively formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy, The first calculation means uses the following formula by the FP method: ψ=λ FEM [0, ψ] φ=λ FEM [i,0] W mp = W FEM [0, ψ] W mc = W FEM [i,0] W mm =W FEM [i, ψ]-W FEM [0, ψ]-W FEM [i, 0] A torque calculation device, wherein the second calculation means uses the formula [2].

3. W ＦＥＭ 3. The torque calculation device according to claim 1, wherein [i, ψ] is magnetic energy calculated based on the results of nonlinear magnetic field analysis.

4. A torque calculation method for calculating torque of a permanent magnet synchronous motor, comprising: a first calculation step in which a first calculation means calculates magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step in which second calculation means calculates torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy, In the first calculation step, the following formula is used according to the FP method: ψ=λ FEM [0, ψ] φ=λ FEM [i,0] W mp = W FEM [0, ψ] W mc = W FEM [i,0] W mm =W FEM [i, ψ]-W FEM [0, ψ]-W FEM [i, 0] The torque calculation method, wherein the second calculation step uses the formula [1].

5. A torque calculation method for calculating torque of a permanent magnet synchronous motor, comprising: a first calculation step in which a first calculation means calculates magnetic flux and magnetic energy in the permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step in which second calculation means calculates torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy, In the first calculation step, the following formula is used according to the FP method: ψ=λ FEM [0, ψ] φ=λ FEM [i,0] W mp = W FEM [0, ψ] W mc = W FEM [i,0] W mm =W FEM [i, ψ]-W FEM [0, ψ]-W FEM [i, 0] The torque calculation method, wherein the second calculation step uses the formula [2].

6. On the computer, a first calculation step of calculating magnetic flux and magnetic energy in a permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step of calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; In the first calculation step, the following formula is used according to the FP method: ψ=λ FEM [0, ψ] φ=λ FEM [i,0] W mp = W FEM [0, ψ] W mc = W FEM [i,0] W mm =W FEM [i, ψ]-W FEM [0, ψ]-W FEM [i, 0] A program in which the formula [1] is used in the second calculation step.

7. On the computer, a first calculation step of calculating magnetic flux and magnetic energy in a permanent magnet synchronous motor by a frozen permeability (FP) method; a second calculation step of calculating a torque of the permanent magnet synchronous motor using the calculated magnetic flux and magnetic energy and equations that formulate magnet torque, cogging torque, and reluctance torque based on the law of conservation of energy; In the first calculation step, the following formula is used according to the FP method: ψ=λ FEM [0, ψ] φ=λ FEM [i,0] W mp = W FEM [0, ψ] W mc = W FEM [i,0] W mm =W FEM [i, ψ]-W FEM [0, ψ]-W FEM [i, 0] A program in which the formula [2] is used in the second calculation step. [Equation 1] [Equation 2]

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