Drive system for a rotating electric machine of the permanent magnet type and drive method for a rotating electric machine of the permanent magnet type

Abstract

It is a task to drive a rotating permanent magnet electric machine incorporating eddy current suppression elements under a control condition capable of suppressing eddy current losses throughout the rotor. A drive system (3) for a rotating permanent magnet electric machine comprises: a rotating permanent magnet electric machine (1) having a stator with a stator core and stator coil (12) and a rotor with a rotor core, a plurality of permanent magnets, and eddy current suppression elements; an inverter (30); and a control device (31) for determining a carrier frequency. The control device determines the carrier frequency greater than a loss overlap frequency calculated from formulas using the dimensions and physical constants of the permanent magnets and the eddy current suppression elements.

Description

Technical field

[0001] The present invention relates to a drive system for a rotating electric machine of the permanent magnet type and a drive method for a rotating electric machine of the permanent magnet type. State of the art

[0002] In a rotating electric machine of the permanent magnet type, which has permanent magnets in a rotor, an eddy current flows through the permanent magnets during rotational operation. When such an eddy current flows through the permanent magnets, an increase in resistance and a temperature rise of the permanent magnet occur as a result of the eddy current, leading to demagnetization and causing power losses known as eddy current losses.

[0003] In a conventional rotating electric machine capable of suppressing the eddy current flowing through permanent magnets, a structure is disclosed in which eddy current suppression elements with high conductivity are arranged on the outer circumferences of the permanent magnets (see, for example, patent document 1). Bibliography Patent document

[0004] Patent document 1: Japanese patent application disclosure JP 2002-345189A Summary of the invention Problem to be solved with the invention

[0005] In a conventional rotating electric machine, where the eddy current suppression elements are arranged on the outer circumferences of the permanent magnets, the eddy current also flows through the eddy current suppression elements, and therefore - depending on a control condition - the eddy current losses increase, including those in the permanent magnets and the eddy current suppression elements.

[0006] The present invention was designed to solve the above problem, and it is an object of the present invention to drive, in a drive system for a rotating electric machine of the permanent magnet type having eddy current suppression elements, the rotating electric machine of the permanent magnet type under a control condition which can suppress the eddy current losses, including those in the permanent magnets and the eddy current suppression elements. Ways to solve the problem

[0007] A drive system for a rotating electric machine of the permanent magnet type according to the present invention comprises: a rotating electric machine of the permanent magnet type, comprising a stator with an annular stator core and a stator coil wound on the stator core, and a rotor with a rotor core attached to a rotating shaft and a plurality of permanent magnets embedded in the rotor core; an inverter that outputs drive energy to the stator coil; and a control device that determines a carrier frequency for the inverter and controls an output of the inverter.

[0008] The majority of permanent magnets are arranged in the circumferential direction, and an eddy current suppression element is arranged on a generating surface for the magnetic flux of at least one of the permanent magnets, with an insulating element inserted between them.

[0009] If, in cross-section along a plane perpendicular to the rotating shaft, the longitudinal length of the generating surface for the magnetic flux of one permanent magnet is a width d1, the depth of the generating surface for the magnetic flux of one permanent magnet is h1, the electrical conductivity of one permanent magnet is σ1, the magnetic permeability of one permanent magnet is µ1, the longitudinal length of a surface opposite one permanent magnet of the eddy current suppression element is a width d2, the depth of the surface opposite one permanent magnet of the eddy current suppression element is h2, the electrical conductivity of the eddy current suppression element is σ2, and the magnetic permeability of the eddy current suppression element is µ2, the control device determines the carrier frequency greater than a frequency f, which is calculated from the following seven formulas: δ1=1πfσ1μ1, δ2=1πfσ2μ2, A(d1 / δ1)=sinh(d1 / δ1)+sin(d1 / δ1)cosh(d1 / δ1)−cos(d1 / δ1), A(d2 / δ2)=sinh(d2 / δ2)+sin(d2 / δ2)cosh(d2 / δ2)−cos(d2 / δ2), B(d1 / δ1)=sinh(d1 / δ1)−sin(d1 / δ1)cosh(d1 / δ1)−cos(d1 / δ1), B(d2 / δ2)=sinh(d2 / δ2)−sin(d2 / δ2)cosh(d2 / δ2)−cos(d2 / δ2), und h1σ1δ1B(d1 / δ1){h1μ1d2δ1A(d1 / δ1)}2+{h1μ1d2δ1B(d1 / δ1)}2=h1σ1δ1B(d1 / δ1)+h2σ2δ2B(d2 / δ2){h1μ1d2δ1A(d1 / δ1)+h2μ2d2δ2A(d2 / δ2)}2+{h1μ1d2δ1B(d1 / δ1)+h2μ2d2δ2B(d2 / δ2)}2. Wirkung der Erfindung

[0010] In the drive system for a rotating electric machine of the permanent magnet type according to the present invention, the following applies: Since the control device determines the carrier frequency greater than the frequency f calculated from the seven formulas, it is possible to drive the rotating electric machine of the permanent magnet type under such a control condition that can suppress eddy current losses, including those in the permanent magnets and the eddy current suppression elements. Brief description of the drawings Fig. Figure 1 is a sectional view of a rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 2 is an enlarged sectional view of a rotor of the rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 3 is a configuration diagram of a drive system for a rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 4 is a characteristic curve graph of eddy current losses in the rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 5 is a characteristic curve graph showing an example of the relationship between a loss overlap frequency and the width of a permanent magnet in the rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 6 is an enlarged sectional view of a rotor of another rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 7 is an enlarged sectional view of a rotor of a rotating electric machine of the permanent magnet type according to embodiment 2. Fig. Figure 8 is an enlarged sectional view of a rotor of a rotating electric machine of the permanent magnet type according to embodiment 3. Fig. Figure 9 is an enlarged sectional view of a rotor of a rotating electric machine of the permanent magnet type according to embodiment 4. Fig. Figure 10 shows a hardware configuration for implementing a control device of the drive system for a rotating electric machine of the permanent magnet type according to each of embodiments 1 to 4. Description of embodiments

[0011] A drive system for a rotating permanent magnet electric machine according to the embodiments for carrying out the present invention is described in detail below with reference to the drawings. In the drawings, identical reference numerals denote identical or corresponding components. Design 1

[0012] Fig. Figure 1 is a sectional view of a rotating electric machine of the permanent magnet type according to embodiment 1. Fig. Figure 1 is a sectional view along the direction perpendicular to the rotating shaft of the permanent magnet type electric machine.

[0013] A rotating electric machine 1 of the permanent magnet type of the present embodiment has a rotor 20 attached to a rotating shaft 2 and a cylindrical stator 10 arranged coaxially on the outer circumferential side of the rotor 20. A gap G is formed between the rotor 20 and the stator 10. The stator 10 is held in a cylindrical frame (not shown). The rotating shaft 2 is held by a pair of jaws (not shown) via bearings. The jaws are fixed at both ends in the axial direction of the frame.

[0014] Here, the direction parallel to the axis of the rotating shaft 2 is referred to as the axial direction, the direction perpendicular to the axis of the rotating shaft 2 is referred to as the radial direction, and the direction in which the rotor 20 rotates around the axis of the rotating shaft 2 is referred to as the circumferential direction.

[0015] The stator 10 has an annular stator core 11 and a stator coil 12 wound on the stator core 11. The stator core 11 has an annular core back face 13 and a plurality of teeth 14 projecting radially inwards from the inner circumferential surface of the core back face 13. Forty-eight teeth 14 are arranged at equal intervals or in the same grid pattern in the circumferential direction. The stator coil 12 is wound on the stator core 11 by means of a distributed winding over a plurality of the teeth 14.

[0016] The rotor 20 has a rotor core 21 with a rotating shaft entry hole into which the rotating shaft 2 is inserted, and twenty-two permanent magnets 22 embedded in the rotor core 21. The rotor core 21 is attached to the rotating shaft 2, which is inserted into the rotating shaft entry hole. Fig. The arrows shown at the permanent magnets 22 indicate the directions of the magnetic fluxes generated by the permanent magnets 22. The stator core 11 and the rotor core 21, for example, are formed by electromagnetic steel laminations stacked in the axial direction.

[0017] Fig. Figure 2 is an enlarged sectional view of a magnetic pole of the rotor of the rotating electric machine of the permanent magnet type according to the present embodiment. Fig. Figure 2 is a sectional view along the direction perpendicular to the rotating shaft of the permanent magnet type electric machine.

[0018] In the rotor 20 of the present embodiment, a magnetic pole is formed from four permanent magnets 22. A magnetic pole has a two-layer structure in which pairs of two permanent magnets 22 are arranged in V-shapes. Of the pairs of two permanent magnets 22 arranged in V-shapes, the permanent magnets 22 on the outer circumferential side are defined as a first layer, and the permanent magnets 22 on the inner circumferential side are defined as a second layer.

[0019] At both ends of each permanent magnet 22, flux barriers 23 with a lower magnetic permeability than the magnetic permeability of the rotor core 21 are formed. In the rotating permanent magnet electric machine 1 of the present embodiment, each flux barrier 23 is formed as a through-hole that penetrates the rotor core 21 in the axial direction. In the rotating permanent magnet electric machine 1 of the present embodiment, the flux barrier 23 is formed as part of a magnet receiving hole in which the permanent magnet 22 and the like can be received.

[0020] As in Fig. As shown in Figure 2, an eddy current suppression element 25 is arranged on the inner circumferential side of a generating surface for the magnetic flux of the permanent magnet 22 in the second layer, with an insulating element 24 inserted between them. The insulating element 24 is, for example, made of insulating resin. The eddy current suppression element 25 is made of a material with a higher electrical conductivity than that of the permanent magnet 22 and the rotor core 21, e.g., copper or aluminum.

[0021] In the sectional view, which is shown in Fig. As shown in Figure 2, the length in the longitudinal direction of the generating surface for the magnetic flux of the permanent magnet 22 is defined as a width d, the length in the depth direction of the generating surface for the magnetic flux of the permanent magnet 22 is defined as a height h, and the length in the axial direction of the permanent magnet 22 is defined as a thickness a. The dimensions of the eddy current suppression element 25 are also defined in the same way.

[0022] Since the electrical conductivity of the eddy current suppression element 25 is greater than that of the permanent magnet 22 and the rotor core 21, the eddy current generated in the rotor 20 is primarily generated within the eddy current suppression element 25. The eddy current generated within the eddy current suppression element 25 can suppress a magnetic field associated with the adjacent permanent magnet 22 through its demagnetizing field generation effect. Consequently, the eddy current suppression element 25 can suppress the eddy current generated in the permanent magnet 22.

[0023] Fig. Figure 3 is a configuration diagram of a drive system for a rotating permanent magnet electric machine according to the present embodiment. A drive system 3 for a rotating permanent magnet electric machine of the present embodiment comprises the rotating permanent magnet electric machine 1, an inverter 30, and a control device 31. The inverter 30 is connected to the rotating permanent magnet electric machine 1. A DC power supply 32 is connected to the inverter 30. The DC power supply 32 supplies DC power to the inverter 30.

[0024] The inverter 30 is controlled by the control unit 31. The control unit 31 receives detection information, such as the rotational position of the rotor 20 of the permanent magnet rotating electric machine 1 and the current flowing through the stator coil 12. Based on the input detection information and command values ​​for speed, torque, and the like, the control unit 31 generates a command voltage and outputs the command voltage to the inverter 30.

[0025] The inverter 30 performs a switching operation according to the voltage command input from the control unit 31. In the inverter 30, the switching operation is determined by pulse width modulation (PWM control) based on the carrier frequency of a carrier wave and the command voltage transmitted by the control unit 31.

[0026] Next, the reason why the eddy current losses in the permanent magnet can be reduced in the drive system for a rotating electric machine of the permanent magnet type of the present embodiment will be described.

[0027] For the drive system of a rotating electric machine of the permanent magnet type of the present embodiment, the following applies: When the permanent magnet is excited in the vertical direction with an angular frequency ω and an average magnetic flux density B0, the eddy current losses P in the permanent magnet are given by the following formula (1). Here, a is the thickness of the permanent magnet, d is the width of the permanent magnet, h is the height of the permanent magnet, σ is the electrical conductivity of the permanent magnet, and µ is the magnetic permeability of the permanent magnet. Furthermore, the eddy current losses in the eddy current suppression element can also be given by formula (1). [Mathematical expression 8] P=ahσω2d2δ|B0|28sinh(d / δ)−sin(d / δ)cosh(d / δ)−cos(d / δ)

[0028] Here, δ is defined by the following formula (2). [Mathematical expression 9] δ=2ωσμ

[0029] By specifying a boundary condition such that the average magnetic flux density B0 is constant, the eddy current losses in the permanent magnet 22 and the eddy current losses in the eddy current suppression element 25 can be calculated individually using formulas (1) and (2). Eddy current losses are also generated in the rotor core 21, and it is subsequently assumed that their magnitude is not affected by the presence or absence of the eddy current suppression element 25. That is, the difference between the eddy current losses in the permanent magnet 22 when the eddy current suppression element 25 is absent and the sum of the eddy current losses in the permanent magnet 22 and the eddy current losses in the eddy current suppression element 25 when the eddy current suppression element 25 is present is the difference in eddy current losses in the entire rotor.

[0030] Fig. Figure 4 is a characteristic curve graph showing eddy current losses in the permanent magnet 22 and the sum of the eddy current losses in the permanent magnet 22 and in the eddy current suppression element 25, specifically in the rotating permanent magnet electric machine of the present embodiment. The solid line indicates the sum of eddy current losses in the permanent magnet 22 and in the eddy current suppression element 25 when the eddy current suppression element 25 is present, and the dashed line indicates eddy current losses in the permanent magnet 22 when the eddy current suppression element 25 is not present.

[0031] In Fig. In equation 4, the horizontal axis represents the frequency, and the vertical axis represents a relative value of the eddy current losses. The frequency on the horizontal axis is denoted by ω / 2π. In equations (1) and (2), Ampère's law is applied, and the line integral of a surface magnetic field is assumed to be constant, resulting in a characteristic curve of eddy current losses with respect to frequency, as shown in Fig. 4 shown.

[0032] The following applies to permanent magnet 22: The relative permeability µ is 1.05, the electrical conductivity σ is 747562 S / m, the thickness a is 10 mm, the width d is 20 mm, and the height h is 6 mm. Regarding the eddy current suppression element 25s, the following applies: The relative permeability µ is 1.0, the electrical conductivity σ is 45978465 S / m, the thickness a is 10 mm, the width d is 20 mm, and the height h is 0.3 mm.

[0033] As in Fig. As shown in Figure 4, at frequencies above a specific frequency, the eddy current losses decrease when the eddy current suppression element is present. However, at frequencies below this specific frequency, the eddy current losses increase when the eddy current suppression element is present. The electrical conductivity of the eddy current suppression element is greater than that of the permanent magnet. Therefore, in a low-frequency range, the following applies: When the eddy current suppression element is present, the eddy current losses within this element are added, thus increasing the overall eddy current losses.

[0034] However, in a high-frequency range, a magnetic flux linked to the eddy current suppression element is suppressed due to the skin effect, thus reducing the eddy current losses in the eddy current suppression element. As a result, in the high-frequency range, the sum of the eddy current losses in the permanent magnet and the eddy current suppression element, when the eddy current suppression element is present, is smaller than the eddy current losses in the permanent magnet when the eddy current suppression element is absent.

[0035] Therefore, it turns out that there is a frequency range where eddy current losses throughout the rotor can be reduced by the eddy current suppression element. As in Fig. As shown in Figure 4, the frequency at the intersection of a curve of eddy current losses when the eddy current suppression element is present and a curve of eddy current losses when the eddy current suppression element is not present is referred to as a loss intersection frequency.

[0036] The dimensions and physical constants of the permanent magnet and the eddy current suppression element are defined as follows. The symbols in parentheses denote units. Permanent magnet h1: Height (m) d1: Width (m) σ1: electrical conductivity (S / m) µ1: magnetic permeability (H / m) Eddy current suppression element h2: Height (m) d2: Width (m) σ2: electrical conductivity (S / m) µ2: magnetic permeability (H / m)

[0037] Here, µ1 and µ2 are expressed by the following two formulas, where µr1 The relative permeability of the permanent magnet is µ. r2 is the relative permeability of the eddy current suppression element and µ0 is the permeability in a vacuum. μ1=.−μr1×μ0 μ2=.−μr2×μ0

[0038] A boundary condition is specified according to which the average magnetic flux density B0 and the line integral of a surface magnetic field are constant, and it is assumed that the thicknesses a1, a2 of the permanent magnet and the eddy current suppression element are sufficiently larger than their widths d1, d2. The loss overlap frequency f at which the sum of the eddy current losses in the permanent magnet and in the eddy current suppression element, when the eddy current suppression element is present, and the eddy current losses in the permanent magnet, when the eddy current suppression element is absent, are equal, can be calculated from the following formulas (3) to (6).

[0039] Formulas (3) to (5) are calculation formulas for the permanent magnet when n is 1, and they are calculation formulas for the eddy current suppression element when n is 2. [Mathematical expression 10] δn=1πfσnμn [Mathematical expression 11] A(dn / δn)=sinh(dn / δn)+sin(dn / δn)cosh(dn / δn)−cos(dn / δn) [Mathematical expression 12] B(dn / δn)=sinh(dn / δn)−sin(dn / δn)cosh(dn / δn)−cos(dn / δn) [Mathematical expression 13] h1σ1δ1B(d1 / δ1){h1μ1d2δ1A(d1 / δ1)}2+{h1μ1d2δ1B(d1 / δ1)}2=h1σ1δ1B(d1 / δ1)+h2σ2δ2B(d 2 / δ2){h1μ1d2δ1A(d1 / δ1)+h2μ2d2δ2A(d2 / δ2)}2+{h1μ1d2δ1B(d1 / δ1)+h2μ2d2δ2B(d2 / δ2)}2

[0040] Using the formulas above, the loss overlap frequency f is calculated with respect to the width d1 of the permanent magnet, and the result is given in Fig. 5 shown. Fig. Figure 5 is a characteristic curve graph showing an example of the relationship between the width of the permanent magnet and the loss overlap frequency in the rotating permanent magnet electric machine of the present embodiment. Fig. In figure 5, the horizontal axis represents the width d1 of the permanent magnet, and the vertical axis represents the loss overlap frequency. The characteristic described in Fig. The value shown in 5 was calculated under the following condition: h1 = 0.006 m, h2 = 0.0003 m, σ1 = 747562 S / m, σ2 = 45978465 S / m, µ1 = 1.05 H / m, µ2 = 1.0 H / m, and d1 and d2 are equal to each other.

[0041] If the permanent magnet is excited at a frequency higher than the loss overlap frequency, which is determined according to the width of the permanent magnet in Fig. As determined in 5, the eddy current losses in the entire rotor are smaller in a case where the eddy current suppression element is present. From Fig. Figure 5 shows that the loss overlap frequency changes significantly depending on the width of the permanent magnet. An eddy current flowing through the permanent magnet contributes to an increase in its temperature. Therefore, in cases where a temperature increase of the permanent magnet is a concern, the carrier frequency in PWM control can be set to a frequency higher than the loss overlap frequency, provided the eddy current suppression element is in place.

[0042] More precisely: In the case of the rotating electric machine of the permanent magnet type, which is in Fig. As shown in Figure 2, the width of the permanent magnet 22 in the first layer is specified as 10 mm, and the width of the permanent magnet 22 in the second layer is specified as 20 mm. At this time, in Fig. 5. The loss overlap frequency, when the width of the permanent magnet is 20 mm, is 1.9 kHz. In a case where the eddy current suppression element is present, the following applies: If the carrier frequency in the PWM control is set to 1.9 kHz or higher, the magnet temperature can be made lower than in a case where the eddy current suppression element is not present.

[0043] Examples of measurement methods for the temperature of the permanent magnet include: a method for directly measuring the temperature of the permanent magnet during driving, and a method for estimating the magnet temperature from other physical information about the rotating permanent magnet type electric machine, e.g., the rotational speed or an elapsed control time.

[0044] The drive system for a rotating permanent magnet electric machine, configured as described above, can reduce eddy current losses throughout the rotor by operating at a frequency higher than the loss overlap frequency determined by the width of the permanent magnet in the second layer.

[0045] In the rotating permanent magnet electric machine of the present embodiment, the eddy current suppression element is present only on the permanent magnet in the second layer. In a case where the width of the permanent magnet 22 in the second layer is specified as 20 mm, the following applies: If the carrier frequency is specified at 1.9 kHz or higher, the eddy current losses in the permanent magnet and in the eddy current suppression element in the second layer are reduced.

[0046] However, the following applies to the permanent magnet in the first layer: Since this permanent magnet is located close to the gap G, an eddy current occurs in a low-frequency range due to the slot harmonics. The frequency of this eddy current is lower than the loss overlap frequency. Therefore, the eddy current losses in the permanent magnet of the first layer are greater when the eddy current suppression element is present. For this reason, in the rotating permanent magnet electric machine of the present embodiment, the eddy current suppression element is only present on the permanent magnet in the second layer.

[0047] Fig. Figure 6 is an enlarged sectional view of a magnetic pole of a rotor of another rotating permanent magnet electric machine according to the present embodiment. In this rotating permanent magnet electric machine, the eddy current suppression element 25 is arranged on the outer circumferential side of the magnetic flux-generating surface of the permanent magnet 22 in the second layer, with the insulating element 24 inserted between them.

[0048] As in Fig. 2 and Fig. As shown in Figure 6, the following applies to the rotating permanent magnet electric machine according to the present embodiment: If the eddy current suppression element 25 is arranged at a position opposite the magnetic flux-generating surface of the permanent magnet 22, it is possible to suppress the eddy current losses throughout the rotor by operating at a frequency higher than the loss overlap frequency. Therefore, the eddy current suppression element 25 can be arranged on one or both of the surfaces opposite the magnetic flux-generating surface of the permanent magnet 22. Design 2

[0049] Fig. Figure 7 is an enlarged sectional view of a magnetic pole of a rotor of the rotating permanent magnet electric machine according to embodiment 2. The structure of the rotating permanent magnet electric machine according to the present embodiment is the same as the structure of the rotating permanent magnet electric machine in embodiment 1, except for the structure of the rotor.

[0050] The configuration of a drive system for a rotating electric machine of the permanent magnet type according to the present embodiment is also the same as the configuration described in Fig. 3 is shown in embodiment 1.

[0051] As in Fig. As shown in Figure 7, in the rotating electric machine of the permanent magnet type according to the present embodiment, the eddy current suppression element 25 is arranged on the inner circumferential side of the generating surface for the magnetic flux of the permanent magnet 22 in the second layer, with the insulating element 24 inserted between them, and the eddy current suppression element 25 is arranged on the inner circumferential side of the generating surface for the magnetic flux of the permanent magnet 22 in the first layer, with the insulating element 24 inserted between them.

[0052] In the rotating electric machine of the permanent magnet type according to the present embodiment, the width of the permanent magnet 22 in the second layer is 20 mm, and the width of the permanent magnet 22 in the first layer is 10 mm. From the relationship of the loss overlap frequency with respect to the width of the permanent magnet, as in Fig. Figure 5 shows that for embodiment 1, the loss overlap frequency is 7.7 kHz when the width of the permanent magnet is 10 mm.

[0053] For this rotating electric machine of the permanent magnet type, the following applies: If the carrier frequency in the PWM control is set to 7.7 kHz or higher, the eddy current losses in the permanent magnet and in the eddy current suppression element in the first layer can be suppressed, and the eddy current losses in the permanent magnet and in the eddy current suppression element in the second layer can be suppressed.

[0054] As described above, in the drive system for a rotating electric machine of the permanent magnet type of the present embodiment, it is possible to suppress the eddy current losses throughout the rotor by operating at a frequency higher than the loss overlap frequency, which is determined by the width of the permanent magnet in the first layer. embodiment 3

[0055] Fig. Figure 8 is an enlarged sectional view showing a magnetic pole of a rotor of a rotating permanent magnet electric machine according to embodiment 3. The structure of the rotating permanent magnet electric machine according to the present embodiment is the same as the structure of the rotating permanent magnet electric machine in embodiment 1, with the exception of the rotor structure. The configuration of a drive system for a rotating permanent magnet electric machine according to the present embodiment is also the same as the configuration described in [reference missing]. Fig. 3 is shown in embodiment 1.

[0056] As in Fig. As shown in Figure 8, in the rotating permanent magnet electric machine according to the present embodiment, a magnetic pole is formed from six permanent magnets 22. Each magnetic pole has a three-layer structure in which pairs of two permanent magnets 22 are arranged in V-shapes. The eddy current suppression element 25 is arranged on the inner circumferential side of the magnetic flux-generating surface of the permanent magnet 22 in the third layer, with the insulating element 24 inserted between them.

[0057] In the rotating electric machine of the permanent magnet type according to the present embodiment, the width of the permanent magnet 22 in the third layer is 20 mm, the width of the permanent magnet 22 in the second layer is 15 mm, and the width of the permanent magnet 22 in the first layer is 10 mm. From the relationship of the loss overlap frequency with respect to the width of the permanent magnet, as in Fig. As shown in embodiment 1, the loss overlap frequency is 1.9 kHz when the width of the permanent magnet is 20 mm. For this rotating electric machine of the permanent magnet type, the following applies: If the carrier frequency in the PWM control is set to 1.9 kHz or higher, the eddy current losses in the permanent magnet and in the eddy current suppression element in the third layer can be suppressed.

[0058] As described above, in the drive system for a rotating electric machine of the permanent magnet type of the present embodiment, it is possible to suppress the eddy current losses throughout the rotor by operating at a frequency higher than the loss overlap frequency, which is determined by the width of the permanent magnet in the third layer.

[0059] In the rotating permanent magnet electric machine of the present embodiment, one magnetic pole can be formed as a multilayer structure with four or more layers, wherein pairs of two permanent magnets are arranged in V-shapes. In the one magnetic pole formed as a multilayer structure, the eddy current suppression element can be arranged on the permanent magnet in the layer on the innermost circumferential side, with the insulating element inserted between them. Design 4

[0060] Fig. Figure 9 is an enlarged sectional view of a magnetic pole of a rotor of the permanent magnet-type rotating electric machine according to embodiment 4. The structure of the permanent magnet-type rotating electric machine according to the present embodiment is the same as the structure of the permanent magnet-type rotating electric machine in embodiment 1, with the exception of the rotor structure. The configuration of a drive system for a permanent magnet-type rotating electric machine according to the present embodiment is also the same as the configuration described in embodiment 1. Fig. 3 is shown in embodiment 1.

[0061] As in Fig. As shown in Figure 9, in the rotating electric machine of the permanent magnet type according to the present embodiment, a magnetic pole is formed from three permanent magnets 22. A magnetic pole is formed from one permanent magnet 22 on the inner circumferential side, which has a generating surface for the magnetic flux in a direction perpendicular to the radial direction, and two permanent magnets 22 on the outer circumferential side, which are located separately at both ends of the permanent magnet 22 on the inner circumferential side.

[0062] Two permanent magnets 22 on the outer circumferential side have magnetic flux-generating surfaces in directions along the radial direction. The eddy current suppression element 25 is arranged on the inner circumferential side of the magnetic flux-generating surface of the permanent magnet 22 on the inner circumferential side, with the insulating element 24 inserted between them.

[0063] In the rotating electric machine of the permanent magnet type according to the present embodiment, the width of the permanent magnet 22 on the inner circumferential side is 20 mm. From the relationship of the loss overlap frequency with respect to the width of the permanent magnet, as in Fig. As shown in embodiment 1, the loss overlap frequency is 1.9 kHz when the width of the permanent magnet is 20 mm. For this rotating permanent magnet electric machine, the following applies: If the carrier frequency in the PWM control is set to 1.9 kHz or higher, the eddy current losses in the permanent magnet and in the eddy current suppression element on the inner circumferential side can be suppressed.

[0064] As described above, in a drive system for a rotating electric machine of the permanent magnet type of the present embodiment, it is possible to suppress the eddy current losses throughout the rotor by operating at a frequency higher than the loss overlap frequency, which is determined by the width of the permanent magnet on the inner circumferential side.

[0065] As in a hardware example in Fig. As shown in Figure 10, the control device 31 comprises a processor 100 and a memory device 101. The memory device includes a volatile memory device, such as a selective-access memory, and a non-volatile auxiliary memory device, such as flash memory, which are not shown. A hard disk as an auxiliary memory device may also be used instead of flash memory.

[0066] Processor 100 executes a program input from memory device 101. In this case, a program is input from the auxiliary memory device to Processor 100 via the volatile memory device. Processor 100 can output data, such as a calculation result, to the volatile memory device of memory device 101, or it can store the data in the auxiliary memory device via the volatile memory device.

[0067] Although the invention is described above in the form of various exemplary embodiments, it is understood that the various features, aspects and functionalities described in one or more of the individual embodiments are not limited in their applicability to the particular embodiment in which they are described, but can instead also be applied - alone or in various combinations - with one or more of the embodiments of the invention.

[0068] It is therefore understood that numerous modifications can be used, which are not described by way of example, without deviating from the scope of the present invention. For example, at least one of the components can be modified, added, or omitted. At least one of the components described in at least one of the preferred embodiments can be selected and combined with the components described in another preferred embodiment. Reference symbol list 1 rotating electric machine of the permanent magnet type 2. Rotating shaft 3 Drive system for a rotating electric machine of the permanent magnet type 10 Stator 11 Stator core 12 Stator coil 13 Core back 14 teeth 20 Rotor 21 Rotor core 22 permanent magnet 23 River barrier 24 insulating element 25 Eddy current suppression element 30 inverters 31 Control unit 32 DC power supply 100 processor 101 Storage setup QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2002- 345 189 A

[0004] Cited non-patent literature

[0000] Mathematical expression 8]

[0027]

Claims

[1] Drive system for a permanent magnet type rotating electrical machine, comprising: - a permanent magnet type rotating electric machine comprising a stator having an annular stator core and a stator coil wound on the stator core, and a rotor having a rotor core fixed to a rotating shaft and a plurality of permanent magnets embedded in the rotor core; - an inverter that outputs drive energy to the stator coil; and - a control device that determines a carrier frequency for the inverter and controls an output of the inverter, wherein the plurality of permanent magnets are arranged so as to be arranged in the circumferential direction, and an eddy current suppression element is arranged on a magnetic flux generation surface of at least one of the permanent magnets with an insulating member interposed therebetween, and when, in the cross-section along a plane perpendicular to the rotating shaft, the length in the longitudinal direction of the magnetic flux generation surface of the one permanent magnet is a width d1, the length in the depth direction of the magnetic flux generation surface of the one permanent magnet is h1, the electrical conductivity of the one permanent magnet is σ1, the magnetic permeability of the one permanent magnet is µ1, the length in the longitudinal direction of a surface opposite the one permanent magnet of the eddy current suppression element is a width d2, the length in the depth direction of the surface opposite the one permanent magnet of the eddy current suppression element is h2, the electrical conductivity of the eddy current suppression element is σ2, and the magnetic permeability of the eddy current suppression element is µ2, the control device determines the carrier frequency to be greater than a frequency f calculated from the following seven formulas: δ1=1πfσ1μ1, δ2=1πfσ2μ2, A(d1 / δ1)=sinh(d1 / δ1)+sin(d1 / δ1)cosh(d1 / δ1)−cos(d1 / δ1), A(d2 / δ2)=sinh(d2 / δ2)+sin(d2 / δ2)cosh(d2 / δ2)−cos(d2 / δ2), B(d1 / δ1)=sinh(d1 / δ1)−sin(d1 / δ1)cosh(d1 / δ1)−cos(d1 / δ1), B(d2 / δ2)=sinh(d2 / δ2)−sin(d2 / δ2)cosh(d2 / δ2)−cos(d2 / δ2), and h1σ1δ1B(d1 / δ1){h1μ1d2δ1A(d1 / δ1)}2+{h1μ1d2δ1B(d1 / δ1)}2=h1σ1δ1B(d1 / δ1)+h2σ2δ2B(d 2 / δ2){h1μ1d2δ1A(d1 / δ1)+h2μ2d2δ2A(d2 / δ2)}2+{h1μ1d2δ1B(d1 / δ1)+h2μ2d2δ2B(d2 / δ2)}2. [2] A drive system for a permanent magnet type rotating electric machine according to claim 1, wherein the rotor has a plurality of magnetic poles and each of the magnetic poles has a multi-layer structure, with pairs of two of the permanent magnets arranged in V shapes. [3] A drive system for a permanent magnet type rotating electric machine according to claim 2, wherein in each of the magnetic poles having the multi-layer structures, the eddy current suppression member is disposed on the permanent magnet in a layer of the innermost peripheral side with the insulating member interposed therebetween. [4] A drive system for a permanent magnet type rotating electric machine according to any one of claims 1 to 3, wherein the stator coil wound on the stator core is wound in a distributed winding manner. [5] A driving method for a permanent magnet type rotating electric machine comprising a stator having an annular stator core and a stator coil wound on the stator core, and a rotor having a rotor core fixed to a rotating shaft and a plurality of permanent magnets embedded in the rotor core, wherein, the plurality of permanent magnets are arranged so as to be arranged in the circumferential direction, and an eddy current suppression element is arranged on a magnetic flux generating surface of at least one of the permanent magnets with an insulating member interposed therebetween, and when, in the cross-section along a plane perpendicular to the rotating shaft, the length in the longitudinal direction of the magnetic flux generation surface of the one permanent magnet is a width d1, the length in the depth direction of the magnetic flux generation surface of the one permanent magnet is h1, the electrical conductivity of the one permanent magnet is σ1, the magnetic permeability of the one permanent magnet is µ1, the length in the longitudinal direction of a surface opposite the one permanent magnet of the eddy current suppression element is a width d2, the length in the depth direction of the surface opposite the one permanent magnet of the eddy current suppression element is h2, the electrical conductivity of the eddy current suppression element is σ2, and the magnetic permeability of the eddy current suppression element is µ2, the stator coil is operated with a carrier frequency greater than a frequency f, which is calculated from the following seven formulas: δ1=1πfσ1μ1, δ2=1πfσ2μ2, A(d1 / δ1)=sinh(d1 / δ1)+sin(d1 / δ1)cosh(d1 / δ1)−cos(d1 / δ1), A(d2 / δ2)=sinh(d2 / δ2)+sin(d2 / δ2)cosh(d2 / δ2)−cos(d2 / δ2), B(d1 / δ1)=sinh(d1 / δ1)−sin(d1 / δ1)cosh(d1 / δ1)−cos(d1 / δ1), B(d2 / δ2)=sinh(d2 / δ2)−sin(d2 / δ2)cosh(d2 / δ2)−cos(d2 / δ2), und h1σ1δ1B(d1 / δ1){h1μ1d2δ1A(d1 / δ1)}2+{h1μ1d2δ1B(d1 / δ1)}2=h1σ1δ1B(d1 / δ1)+h2σ2δ2B(d2 / δ2){h1μ1d2δ1A(d1 / δ1)+h2μ2d2δ2A(d2 / δ2)}2+{h1μ1d2δ1B(d1 / δ1)+h2μ2d2δ2B(d2 / δ2)}2.

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