JP2010200460A - Permanent magnet type rotary electric machine and electric power steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a permanent magnet type rotary electric machine which increases rotor position dependence of impedance and is suitable for sensorless driving, and to provide an electric power steering device using the same. <P>SOLUTION: A rotatable rotor 4 is inserted into a stator 1. The rotor 4 is provided with a rotation axis 5, a cylindrical rotor core 6 fixed to the rotation axis 5, a plurality of permanent magnets 7 fixed to an outer peripheral face of the rotor core 6 at equal intervals in a circumferential direction, and a plurality of conduction circuit parts 8 fixed to the outer peripheral face of the rotor core 6 to surround a periphery of the permanent magnets 7. The conduction circuit part 8 is divided into a plurality of divided conductors when viewed from a cross section vertical to a length direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a permanent magnet type rotating electric machine in which a plurality of permanent magnets are provided on a rotor, and an electric power steering apparatus using the same.

  In recent years, there has been a demand for cost reduction and miniaturization of permanent magnet type rotating electrical machines such as permanent magnet type motors. A motor driving method that satisfies these requirements includes a sensorless driving method that eliminates the need for a motor angle detection device. In order to perform the sensorless driving method in both the low speed range and the high speed range of the motor, the saliency of the motor is required.

  An example of a motor having a large saliency is an embedded magnet type motor. However, since an embedded magnet type motor has a large cogging torque, torque ripple, etc., electric power steering is required to have a good steering feeling. It is not suitable for equipment. For this reason, there is a demand for a structure that improves saliency in a surface magnet type motor that has low saliency but low cogging torque and torque ripple and good steering feel.

  For example, in a conventional permanent magnet type rotating electrical machine, a nonmagnetic material layer is provided around the rotor for angle detection. In addition, the nonmagnetic layer is formed in angular sections of electrical angles of 80 to 100 degrees in the forward and reverse rotation directions of the rotor around the pole that separates the N pole and the S pole of the rotor. (For example, refer to Patent Document 1).

  In another conventional permanent magnet type rotating electrical machine, a cylindrical member made of a conductive material or a magnetic material is fitted to the outer peripheral portion of the rotor for angle detection (see, for example, Patent Document 2). .

JP-A-9-56193 JP 2006-109663 A

  However, in the conventional permanent magnet type rotating electrical machine as described above, the change in impedance due to the rotor position is small, and the saliency cannot be sufficiently increased.

  The present invention has been made to solve the above-described problems, and can increase the rotor position dependency of impedance, and uses a permanent magnet type rotating electrical machine suitable for sensorless driving, and the same. An object is to obtain an electric power steering device.

  A permanent magnet type rotating electrical machine according to the present invention includes a stator having a stator core and an armature winding provided on the stator core, and a plurality of permanent cores provided on the rotor core and the rotor core. A rotor having a magnet, and the rotor is provided with a conduction circuit portion that is a closed circuit, and the conduction circuit portion includes a plurality of axial conductor portions provided along the axial direction of the rotor. And a plurality of connecting conductors connecting between the axial conductors, and the conductor constituting the conductive circuit part is divided into a plurality of divided conductors when a cross section perpendicular to the length direction is viewed. ing.

  In the permanent magnet type rotating electric machine according to the present invention, by injecting a high-frequency current into the armature winding, a significant difference occurs between the d-axis impedance and the q-axis impedance due to the induced current flowing in the axial conductor portion, and the saliency Becomes larger. Further, since the conductor is divided into a plurality of divided conductors, it is less susceptible to the skin effect, and the saliency is further increased. Thereby, sensorless driving without using a resolver, an encoder, or the like is possible.

It is sectional drawing of the permanent magnet type motor by Embodiment 1 of this invention. It is a perspective view which shows the rotor of FIG. FIG. 3 is an enlarged perspective view showing a pair of permanent magnets and a conduction circuit unit in FIG. 2. It is a perspective view which shows only the conduction circuit part of FIG. It is explanatory drawing which expands and shows the principal part of the permanent magnet type motor of FIG. It is a graph which shows the relationship between the rotation angle of a rotor and the impedance in the permanent magnet type motor of FIG. It is explanatory drawing which shows the locus | trajectory of the current vector which dq-converted the electric current which flows into an armature winding part when a high frequency voltage is applied to the armature winding part of FIG. 1 at the time of no load. It is explanatory drawing which shows the locus | trajectory of the current vector which carried out the dq conversion of the electric current which flows into an armature winding part when a high frequency voltage is applied to the armature winding part of FIG. 1 when there is load. It is a graph which shows the frequency dependence of conductor resistance. It is a schematic block diagram which shows the controller for sensorlessly driving the permanent magnet type motor of FIG. It is sectional drawing of the permanent magnet type motor by Embodiment 2 of this invention. It is a top view which shows the 1st example of the conduction | electrical_connection circuit part of FIG. It is a front view which shows the conduction | electrical_connection circuit part of FIG. It is a front view which shows the 2nd example of the conduction | electrical_connection circuit part of FIG. It is sectional drawing of the permanent magnet type motor by Embodiment 3 of this invention. It is sectional drawing which expands and shows the 1st example of the conduction circuit part of FIG. It is sectional drawing which expands and shows the 2nd example of the conduction | electrical_connection circuit part of FIG. It is sectional drawing which shows the permanent magnet type motor by Embodiment 4 of this invention. It is sectional drawing which shows the 1st example of the permanent magnet type motor by Embodiment 5 of this invention. It is sectional drawing which shows the 3rd example of the permanent magnet type motor by Embodiment 5 of this invention. It is sectional drawing which shows the 4th example of the permanent magnet type motor by Embodiment 5 of this invention. It is a perspective view which shows the rotor of the permanent magnet type motor by Embodiment 6 of this invention. It is a schematic block diagram which shows the electric power steering apparatus by Embodiment 7 of this invention.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
Embodiment 1 FIG.
FIG. 1 is a cross-sectional view of a permanent magnet type motor according to Embodiment 1 of the present invention, showing a surface magnet type motor having 10 poles and 12 slots. In the figure, the stator 1 has a cylindrical stator core 2 and a plurality of armature winding portions 3. The stator core 2 is provided with a plurality of teeth portions 2a protruding radially inward at equal intervals in the circumferential direction. Slot portions 2b are provided between adjacent tooth portions 2a. The armature winding part 3 is wound around the tooth part 2a.

  A rotatable rotor 4 is inserted inside the stator 1. The rotor 4 includes a rotation shaft 5, a cylindrical rotor core 6 fixed to the rotation shaft 5, and a plurality of (this example) fixed to the outer peripheral surface of the rotor core 6 at equal intervals in the circumferential direction. 10) permanent magnets 7 and a plurality of conduction circuit portions 8 fixed to the outer peripheral surface of the rotor core 6 so as to surround the periphery of the permanent magnets 7.

  If the rotation direction of the rotor 4 is counterclockwise in the figure, the winding arrangement is U +, U−, V−, V +, W +, W−, U−, U +, V +, V−, W in the counterclockwise direction. -, W +. However, U + and U− are U-phase windings, V + and V− are V-phase windings, W + and W− are W-phase windings, and + and − are reverse winding directions. Means.

  2 is a perspective view showing the rotor 4 of FIG. 1, FIG. 3 is an enlarged perspective view showing a pair of permanent magnets 7 and a conduction circuit portion 8 of FIG. 2, and FIG. 4 is a conduction circuit portion 8 of FIG. It is a perspective view which shows only. Each conduction circuit portion 8 includes a pair of axial conductor portions 8a and 8b provided along the axial direction of the rotor 4 (parallel or substantially parallel to the axial direction), and both end portions of the axial conductor portions 8a and 8b. It has a pair of connecting conductor parts 8c and 8d that connect them. That is, the conductive circuit part 8 which is a closed circuit is constituted by the axial conductor parts 8a and 8b and the connecting conductor parts 8c and 8d.

  The permanent magnet 7 is inserted through a rectangular opening at the center of the conduction circuit portion 8 and protrudes outward in the radial direction from the conduction circuit portion 8. The axial conductor portions 8 a and 8 b are in contact with both side surfaces of the permanent magnet 7. The connecting conductor portions 8 c and 8 d are in contact with both axial end surfaces of the permanent magnet 7. That is, the axial conductor portions 8a and 8b and the connecting conductor portions 8c and 8d are disposed so as to individually surround the permanent magnets 7.

  The conduction circuit unit 8 is configured by laminating a plurality of (two in this example) conductor plates in the radial direction of the rotor 4 (the thickness direction of the conduction circuit unit 8). That is, the conductor constituting the conduction circuit unit 8 is divided into a plurality of divided conductors when a cross section perpendicular to the length direction is viewed. Furthermore, the conduction circuit unit 8 is made of, for example, copper or aluminum.

  Next, the principle that enables the rotation angle to be detected without a rotation sensor will be described. FIG. 5 is an explanatory view showing the main part of the permanent magnet type motor of FIG. 1 expanded linearly, and shows two rotor positions d and q. The waveform of the fundamental wave component of the magnetic flux generated by the armature current when the high frequency voltage is applied is shown between the stator 1 and the rotor 4.

  For detecting the rotation angle, saliency is used. Here, the saliency means the dependency of impedance on the rotor position. Moreover, the impedance here means the impedance between the lines of the armature winding part 3, for example, and such impedance is hereinafter simply referred to as impedance.

  In FIG. 5, the rotor positions d and q having the largest impedance difference with respect to the rotor position are compared. First, when the rotor position is d, the magnetic flux generated by the armature current is linked, for example, between the axial conductor portions 8a and 8b, and an induced current flows through the axial conductor portions 8a and 8b. The induced current cancels out the magnetic flux generated by the armature current, and the impedance is reduced.

  On the other hand, when the rotor position is q, the magnetic flux generated by the armature current cancels, for example, the interlinkage between the axial conductor portions 8a and 8b, so that the axial conductor portions 8a and 8b The induced current does not flow and the impedance does not change. Thus, the position of the rotor 4 can be detected by utilizing the phenomenon that a difference (significant difference) occurs in the impedance depending on the position of the rotor 4.

  FIG. 6 is a graph showing the relationship between the rotation angle of the rotor 4 and the impedance in the permanent magnet type motor of FIG. 1, and shows the saliency. In FIG. 6, the horizontal axis indicates the angle (electrical angle) of the rotor 4, and the vertical axis indicates the impedance. In FIG. 6, the period of change in impedance is an electrical angle of 180 degrees. This is possible because the paired axial conductor portions 8a and 8b are arranged at an electrical angle interval of 180 degrees.

  7 is an explanatory diagram showing a locus of a current vector obtained by dq conversion of the current flowing through the armature winding section 3 when a high frequency voltage is applied to the armature winding section 3 of FIG. 1 when there is no load, and FIG. FIG. 3 is an explanatory diagram illustrating a locus of a current vector obtained by dq conversion of a current flowing through the armature winding section 3 when a high frequency voltage is applied to the armature winding section 3 of FIG. 1 at a certain time. 7 and 8, the d-axis current is taken as the horizontal axis and the q-axis current is taken as the vertical axis. The motor is a U-phase, V-phase, and W-phase three-phase motor, and the high-frequency voltage to be applied is a voltage that has the same amplitude as each line voltage but is shifted by 2π / 3 [rad].

  As shown in FIGS. 7 and 8, the locus of the current vector of the conventional motor in which the conduction circuit section 8 is not arranged is such that the d-axis and q-axis impedances do not depend on the rotor position (that is, there is almost no saliency). Therefore, it becomes a perfect circle or almost a perfect circle.

  On the other hand, the locus of the current vector of the motor in which the conduction circuit unit 8 is arranged is elliptical as shown in FIGS. This is because the impedance of the d-axis and the q-axis depends on the rotor position and the current changes by arranging the conduction circuit unit 8. Further, when magnetic saturation occurs during loading, the ellipse may be tilted as shown in FIG. However, even in such a case, the position can be detected from the load current and the inclination in the major axis direction.

  Thus, by arranging the conduction circuit portion 8 around the permanent magnet 7, the saliency when the high frequency voltage is applied to the motor can be increased, and the sensor can be driven by the motor.

  Next, the correlation between the saliency and the accuracy of sensorless driving will be described. The accuracy of position estimation in sensorless driving is better as the difference ΔIh between the d-axis current Idh and the q-axis current Iqh when a high-frequency voltage is applied is larger. The magnitudes of Idh and Iqh are half the lengths of the major and minor axes of the ellipse, respectively, as shown in FIGS. Therefore, ΔIh can be expressed by the following formula (1). Further, in order to evaluate the saliency of the motor, the saliency index was defined by the following formula (2).

  ΔIh is proportional to the product of the index of high frequency voltage and saliency (the difference between the reciprocal of d-axis inductance Ldh and the reciprocal of q-axis inductance Lqh when a high-frequency voltage is applied) and the reciprocal of frequency, so ΔIh is the same. If so, the higher the saliency, the smaller the high-frequency current (or high-frequency voltage Vh) can be suppressed. Further, since the noise of the motor is larger as the high frequency current is larger, the higher the saliency is, the smaller current can secure the accuracy of position estimation, and the noise can be suppressed small.

  Here, the conduction circuit unit 8 of the first embodiment is not a single wire (single conductor wire) or a single conductor, but a plurality of divided conductors (element wires or conductor plates) divided in the radial direction of the rotor 4. ). The number of divisions of the conductive circuit unit 8 may be three or more, and may not be equally divided.

  The divided conductors may be in direct contact with each other or may be separated from each other. Further, when the divided conductors are separated from each other, an air layer or a thin insulating layer may be interposed between the divided conductors.

  If the conductors are divided so that the thickness of each divided conductor is thinner than the predetermined skin depth, the current is not concentrated on the surface of the conductor, so it is less affected by the skin effect and the induced current flowing through the conductor when applying high-frequency voltage is small. Don't be. Therefore, saliency can be maintained and sensorless driving is possible.

  Next, the resistance of the conductor in consideration of the skin effect will be described. When the eddy current is large, when the rotor position is d in FIG. 5, the magnetic flux to be canceled increases, and the d-axis inductance Ldh when the high frequency voltage is applied becomes small. On the other hand, as described above, the q-axis inductance Lqh at the time of applying a high-frequency voltage hardly changes.

  Since the saliency increases as the difference between the reciprocal of Ldh and the reciprocal of Lqh increases, the saliency increases when the eddy current is large when the rotor position is d in FIG. Moreover, since the eddy current is larger when the equivalent resistance of the conductor is smaller, the saliency is higher. Therefore, to increase the saliency, it is necessary to reduce the influence of the skin effect at high frequencies.

  On the other hand, when the conductor is divided so as to be thinner than the skin depth, the equivalent resistance of the conductor becomes almost the same as the DC resistance. For this reason, it is considered useful to divide the conductor to increase the saliency.

  Therefore, how much the influence of the skin effect can be reduced by applying the high-frequency voltage by dividing the conductor will be described by calculating the equivalent resistance of the conductor at each frequency. However, the part where the current flows unevenly is not the entire surface of the conductor but only one side. The method of current bias will be described later. Furthermore, the cross-sectional shape of the conductor is a 1 mm square, and the conductor material is copper.

  FIG. 9 is a graph showing the frequency dependence of the conductor resistance, where the horizontal axis indicates the frequency and the vertical axis indicates the ratio of the cross-sectional area (cross-sectional area of the entire conductor / cross-sectional area of the portion where current flows). This cross-sectional area ratio can be considered to be the same as the resistance ratio (resistance considering the skin effect / DC resistance). The closer this value is to 1, the less the influence of the skin effect is, and the higher the saliency can be maintained. . In the calculation, the cross-sectional area of the portion where the current flows is assumed to flow up to the skin depth. The equivalent resistance of the conductor is the same as the DC resistance until it is affected by the skin effect, and becomes larger than the DC resistance when affected by the skin effect.

The skin depth δ [m] is obtained by the following equation.

  Here, fe is the frequency [Hz] of the eddy current flowing through the conductor, σ is the conductivity [S / m], and μ is the magnetic permeability [H / m].

The frequency fh of the high-frequency current injected into the armature winding portion 3 of the motor and the above fe are not exactly the same because the motor rotates. However, since the frequency fd [Hz] of the current for driving the motor is sufficiently small with respect to fh, the frequency fh of the high-frequency current injected into the armature winding of the motor is considered to be the same as the above fe. it can. Therefore, Equation (3) can be approximated by the following equation.

FIG. 9 was calculated as σ = 5.90 × 10 ⁷ S / m and μ = 1.26 × 10 ⁻⁶ H / m. When the thickness of the conductor is b [m] (see FIG. 4), if the frequency of the high frequency voltage to be applied is equal to or higher than the frequency f1 [Hz] obtained by the following formula, the influence of the skin effect is obtained by dividing the conductor. Can be effectively reduced.

  In FIG. 9, there are three conductors: no division, two divisions, and three divisions. The points on the horizontal axis are 1 kHz, 3 kHz, 5 kHz, 10 kHz, 30 kHz, and 50 kHz.

  Without division, the equivalent resistance starts to increase around 5 kHz. On the other hand, in the case of two divisions, the equivalent resistance up to around 10 kHz is the same as the DC resistance, and is not affected by the skin effect. Further, in the three divisions, the equivalent resistance up to about 30 kHz is the same as the direct current resistance and is not affected by the skin effect.

  Next, how the current is biased will be described. The method of biasing the current differs between when the voltage is directly applied to the conductor and when the induced current flows through the conductor because a part of the magnetic flux generated by the stator is linked to the conductor. That is, in the former, the current is biased over the entire surface of the conductor, and in the latter, the current is biased mainly to the side closer to the stator of the conductor. Therefore, the condition for calculating the above resistance is that the current is biased to only one side.

  As described above, in the permanent magnet type motor of the first embodiment, the conduction circuit portion 8 is provided around the permanent magnet 7, and the conduction circuit portion 8 is set such that the thickness of each divided conductor is smaller than the skin depth. Therefore, an increase in resistance due to the skin effect when a high frequency voltage is applied can be suppressed, and saliency can be maintained. For this reason, the rotor position dependency of impedance can be increased, and a permanent magnet type motor suitable for sensorless driving can be obtained.

  Here, an example of a controller for actually performing sensorless driving will be described. FIG. 10 is a schematic configuration diagram showing a controller for driving the permanent magnet type motor of FIG. 1 sensorlessly. In the figure, a controller 12 is connected to the permanent magnet type motor 11. The controller 12 is connected to the power supply 13. The power source 13 is constituted by a DC power source such as a battery.

  The controller 12 includes an inverter 14, an armature current measurement unit 15, and a rotation angle detection unit 16. The inverter 14 supplies a current to the permanent magnet type motor 11 in order to drive the permanent magnet type motor 11. Further, the inverter 14 superimposes and injects a high frequency current of, for example, several hundred Hz to several tens kHz into the permanent magnet type motor 11 for detection of the rotation angle.

  The armature current measurement unit 15 has a function of measuring the armature current, and is configured by, for example, a hall CT or a shunt resistor. The reason why a sensor such as Hall CT is used is that the armature current is close to direct current immediately after the start of driving of the permanent magnet type motor 11, and therefore it is necessary to measure from direct current to high frequency alternating current. In FIG. 10, the configuration is such that three-phase current is measured, but two-phase may be used, or one-phase current on the power supply side may be measured.

  The current value measured by the armature current measurement unit 15 is input to the rotation angle detection unit 16. The rotation angle detection unit 16 performs arithmetic processing based on the input current value to obtain the rotation angle estimated value θ. At this time, the rotation angle detection unit 16 estimates the rotation angle by, for example, obtaining the major axis direction of the elliptical orbit shown in FIGS. The estimated rotation angle value θ estimated by the rotation angle detector 16 is used by the inverter 14 to appropriately supply a motor driving current.

  Such a controller 12 can detect the rotation angle without separately providing a rotation angle detection device such as a resolver or an encoder. Note that the armature current measuring unit 15 is also provided in a conventional configuration in which a rotation angle is detected by a resolver, an encoder, or the like because it is necessary to grasp a current value during torque control of the permanent magnet type motor 11. Moreover, the rotation angle detection part 16 can be comprised inside the microcomputer and ASIC which are provided also by the conventional structure.

  Therefore, according to the controller 12 of the first embodiment, it is possible to detect the rotation angle with a smaller number of parts than in the prior art, and it is possible to realize motor driving with a lower cost and smaller configuration. In addition, since the permanent magnet type motor 11 of the first embodiment has a large saliency, ΔIh when the magnitude of the high-frequency current is the same is increased, and the accuracy of detection of the rotation angle is increased. For this reason, torque ripple generated due to low detection accuracy of the rotation angle can be reduced.

  In the above example, the permanent magnet 7 protrudes radially outward from the conduction circuit portion 8 and the conduction circuit portion 8 is in contact with the permanent magnet 7, but the permanent magnet 7 has a diameter larger than that of the conduction circuit portion 8. The same effect can be obtained also when the projection does not protrude outward or when the conduction circuit portion 8 is not in contact with the permanent magnet 7.

Embodiment 2. FIG.
In the first embodiment, the conductor dividing method has been described as a means for improving the saliency. In the second embodiment, the dividing direction and the like will be described in detail. However, since the structure which divides | segments a conductor to the radial direction of a motor has been demonstrated in Embodiment 1, it omits.

  11 is a cross-sectional view of a permanent magnet type motor according to Embodiment 2 of the present invention, FIG. 12 is a plan view showing a first example of the conduction circuit unit 8 of FIG. 11, and FIG. 13 shows the conduction circuit unit 8 of FIG. It is a front view. In the figure, the axial conductor portions 8a and 8b of the conductive circuit portion 8 are divided into three in the circumferential direction of the rotor 4 so that the thickness of each divided conductor is thinner than the skin depth. Accordingly, the connection conductor portions 8 c and 8 d are divided into three in the axial direction of the rotor 4. The divided conductors are arranged away from each other. Further, the division method is not limited to equal division. Other configurations are the same as those in the first embodiment.

  Thus, even when the axial conductor portions 8a and 8b are divided in the circumferential direction of the rotor 4, the skin effect when a high-frequency voltage is applied can be reduced. Therefore, by arranging the conductive circuit portion 8 divided as shown in FIG. 12 around the permanent magnet 7, the saliency is improved, sensorless driving is possible, and the motor with a smaller and cheaper configuration than the conventional one. Driving can be realized. Moreover, since the surface area of the conductor is increased by dividing the conductor of the conductive circuit portion 8, heat dissipation is easy.

  FIG. 14 is a front view showing a second example of the conduction circuit unit 8 of FIG. 11, and a plan view thereof is the same as FIG. In the second example, the conduction circuit unit 8 is divided into three in the radial direction of the rotor 4. Further, the axial conductor portions 8 a and 8 b are divided into three in the circumferential direction of the rotor 4, and the connecting conductor portions 8 c and 8 d are divided into three in the axial direction of the rotor 4. Further, the division method is not limited to equal division. Further, the divided conductors are bonded to each other with an insulating adhesive.

  As described above, in the conductor dividing method, the axial conductor portions 8a and 8b are divided in the circumferential direction of the rotor 4, the connecting conductor portions 8c and 8d are divided in the axial direction of the rotor 4, and the conduction circuit portion 8 By dividing the conductor in the axial direction, the axial conductor portions 8a and 8b are divided in the circumferential direction of the rotor 4, and the connecting conductor portions 8c and 8d are divided in the axial direction of the rotor 4, or a conduction circuit The skin effect can be further reduced as compared with the case where the portion 8 is divided in the axial direction of the conductor, whereby saliency can be maintained, and sensorless driving can be performed more efficiently.

Embodiment 3 FIG.
Next, FIG. 15 is a sectional view of a permanent magnet type motor according to Embodiment 3 of the present invention, and FIG. 16 is an enlarged sectional view showing a first example of the conduction circuit portion 8 of FIG. In this example, the conduction circuit unit 8 is configured as a bundle of seven strands (divided conductors) 9 arranged around the permanent magnet 7. Other configurations are the same as those in the first embodiment.

  In such a permanent magnet type motor, since each strand 9 is not coat | covered with the insulator, the adjacent strands 9 are electrically connected. However, since there is a contact resistance between the strands 9, it is less susceptible to the skin effect than when a single wire having the same cross-sectional area as the total cross-sectional area of the strands 9 is used. Therefore, the induced current flowing through the conduction circuit unit 8 when a high frequency voltage is applied is not reduced, saliency can be maintained, and sensorless driving is possible. Moreover, since the strand 9 is used, it is easy to bend and process easily.

In the above example, seven strands 9 are used, but the number of strands 9 is not specified as long as the thickness of the conductor is thinner than the skin depth.
Moreover, as the strand 9 suitable for said 1st example, an annealed copper wire or a tin plating annealed copper wire can be used, for example, and the conduction | electrical_connection circuit part 8 can be comprised by twisting such an strand 9 together. .

  FIG. 17 is an enlarged cross-sectional view showing a second example of the conduction circuit unit 8 of FIG. In the second example, each strand 9 has a strand body 9a and an insulator 9b coated on the outer periphery of the strand body 9a.

  In this way, by forming the conduction circuit portion 8 using the wire 9 having the insulator 9b, it is less susceptible to the skin effect than when using the wire 9 not covered with the insulator 9b. . For this reason, the induced current flowing through the conduction circuit unit 8 when a high-frequency voltage is applied is not reduced, saliency can be maintained, and sensorless driving is possible.

In addition, as a conductor suitable for said 2nd example, there exist the wire which bundled the enamel wire, the litz wire, etc.
Moreover, even if the conductor suitable for said 1st example and 2nd example is not twisted, the effect similar to the case where it twists is acquired.

  Here, in general, the surface magnet type motor has almost no saliency, but the configuration as in the first, second, and third embodiments makes the saliency greater than that of a general surface magnet type motor. be able to. Moreover, in these structures, since the skin effect can be reduced as compared with the case where a conductor that is not divided is arranged around the permanent magnet 7, the saliency is increased. Furthermore, in general, the surface magnet type motor has a small cogging torque and torque ripple, and there is no influence on the cogging torque and torque ripple due to the arrangement of the conductor. Therefore, the original advantage of the surface magnet type motor can be utilized.

Embodiment 4 FIG.
In the first to third embodiments, the configuration that can increase the change in impedance due to the rotor position with respect to the surface magnet type motor has been described. On the other hand, in the fourth embodiment, a case where a similar configuration is applied to an embedded magnet type motor will be described.

  FIG. 18 is a sectional view showing a permanent magnet type motor according to Embodiment 4 of the present invention, and shows an embedded magnet type motor. In this example, the permanent magnet 7 is embedded in the rotor core 6. A plurality of rotor grooves 6 a are provided on the outer peripheral surface of the rotor core 6 so as to surround the periphery of the embedded portion of the permanent magnet 7. In the rotor groove 6a, a conduction circuit portion 8 composed of seven strands 9 is arranged as in the third embodiment. Other configurations are the same as those in the first embodiment.

  Even in such an embedded magnet type motor, by arranging the conduction circuit portion 8 around the embedded portion of the permanent magnet 7, the saliency is improved, sensorless driving is possible, and it is less expensive than the conventional one. Motor drive with a small configuration can be realized.

In addition, since the embedded magnet type motor is easier to hold the magnet than the surface magnet type motor, it is not necessary to provide a tube made of a non-magnetic material such as stainless steel on the outer periphery of the rotor 4.
Furthermore, since the embedded magnet type motor originally has saliency, the saliency can be further improved as compared with the surface magnet type motor.

Embodiment 5 FIG.
In the fifth embodiment, a case where the armature winding part 3 is concentrated winding will be described. In the first to fourth embodiments, only 10 poles and 12 slots have been described, but the above-described configuration can also be adopted in a motor in which the ratio of the number of poles to the number of slots is as follows.

Number of poles: number of slots = 12n ± 2n: 12n (where n is an integer of 1 or more)
Number of poles: number of slots = 9n ± n: 9n (where n is an integer of 1 or more)
Number of poles: number of slots = 3n ± n: 3n (where n is an integer of 1 or more)

  FIG. 19 is a cross-sectional view showing a first example of a permanent magnet type motor according to Embodiment 5 of the present invention, in which an armature winding portion 3 is an example of concentrated winding. The permanent magnet type motor of FIG. 19 has 8 poles and 12 slots, and when the rotation direction of the rotor 4 is counterclockwise, the winding arrangement is such that the winding is repeated four times in the order of U +, V +, and W + counterclockwise. Become. Other configurations are the same as those in the third embodiment.

  Such a concentrated-winding permanent magnet motor originally has a small saliency, but by adopting such a configuration, the skin effect can be reduced, so that the saliency is increased and the rotation sensor can be eliminated.

  FIG. 1 used in the first embodiment also corresponds to a cross-sectional view showing a second example of the permanent magnet type motor according to the fifth embodiment, and the armature winding portion 3 is concentrated winding with 10 poles and 12 slots. An example of a permanent magnet type motor is shown.

  FIG. 20 is a cross-sectional view showing a third example of the permanent magnet type motor according to the fifth embodiment of the present invention. The example is a permanent magnet type motor having 14 poles and 12 slots and the armature winding part 3 being concentrated winding. Show.

  FIG. 21 is a cross-sectional view showing a fourth example of the permanent magnet type rotating electric machine according to the fifth embodiment of the present invention. The permanent magnet motor of the permanent magnet type motor having the 8-pole 9-slot armature winding portion 3 concentrated. An example is shown.

  In the winding arrangement of 14 poles and 12 slots in FIG. 20, when the rotation direction of the rotor 4 is counterclockwise, U +, U−, W−, W +, V +, V−, U−, U +, W +, W-, V-, V +. Further, in the winding arrangement of 8 poles and 9 slots in FIG. 21, when the rotation direction of the rotor 4 is counterclockwise, U +, U−, U +, V +, V−, V +, W +, W− are counterclockwise. , W +.

  Even with the winding arrangements of the second to fourth examples of the fifth embodiment, the same effects as those of the first example can be obtained.

  In addition, although Embodiment 5 demonstrated the case where the armature winding part 3 was concentrated winding, the same effect can be acquired also in the case of distributed winding.

Embodiment 6 FIG.
Next, FIG. 22 is a perspective view showing a rotor 4 of a permanent magnet type motor according to Embodiment 6 of the present invention. In the figure, the conduction circuit portion 8 connects a plurality of axial conductor portions 8e provided between adjacent permanent magnets 7 to the ends of all the axial conductor portions 8e at both axial ends of the rotor 4. And a pair of annular connecting conductor portions 8f and 8g. That is, the conductive circuit portion 8 which is a closed circuit is constituted by the axial conductor portion 8e and the connecting conductor portions 8f and 8g. Moreover, although the conductor which comprises the conduction | electrical_connection circuit part 8 was abbreviate | omitted in the figure, as shown in Embodiment 1 or 2, it is divided | segmented into plurality.

  Even with such a configuration, the skin effect can be reduced, so that the saliency can be maintained, and the motor can be driven without using a rotation angle detection device such as a resolver or an encoder.

Embodiment 7 FIG.
In the seventh embodiment, a specific example in which the rotational position detection according to the present invention is applied to an electric power steering apparatus will be described. FIG. 23 is a schematic configuration diagram showing an electric power steering apparatus according to Embodiment 7 of the present invention.

  A column shaft 32 that receives the steering force of the steering wheel 31 is coupled to the steering wheel 31. A worm gear 33 is connected to the column shaft 32. The steering force of the steering wheel 31 is transmitted to the worm gear 33 via the column shaft 32.

  The worm gear 33 applies the assist torque of the motor 35 to the steering force. At this time, the direction of rotation of the motor 35 is changed to a right angle by the worm gear 33, and the rotation of the motor 35 is decelerated and transmitted.

  The motor 35 is driven and controlled by the controller 34. The worm gear 33 is connected to the handle joint 36. The steering force is transmitted from the worm gear 33 to the handle joint 36, and its direction is changed.

  A steering gear 37 is connected to the handle joint 36. The steering gear 37 converts the rotation of the handle joint 36 into a linear motion of the rack 38 while decelerating. Wheels (not shown) are moved by the linear movement of the rack 38, and the direction of the vehicle can be changed. In FIG. 23, detailed description of the worm gear 33 and the steering gear 37 is omitted, and only the respective gear boxes are shown.

  In such an electric power steering apparatus, it is necessary to detect the rotation angle in order to drive the motor 35 appropriately. Therefore, the conventional motor includes a rotation angle detection device such as a hall sensor or a resolver. However, if there is a Hall sensor or resolver, the number of parts increases and the cost also increases. In addition, the size of the motor 35 is increased due to the rotation angle detection device.

  On the other hand, by using any of the permanent magnet motors shown in the first to sixth embodiments as described above as the motor 35, even if there is no rotation angle detection device, the motor 35 is generated by an induced current flowing in the conductor. The rotation angle can be detected by measuring the armature current using the difference in impedance. That is, the controller 34 superimposes the voltage for driving the motor 35 and applies a high frequency voltage of, for example, several hundred Hz to several tens of kHz to the motor 35, and measures the high frequency current generated thereby, thereby rotating the rotation angle. Detection is possible, and rotation sensorless driving is possible.

  Further, in any of the permanent magnet type motors shown in the first to sixth embodiments, the conductor of the conduction circuit unit 8 is divided, so that the skin effect at the time of applying a high frequency voltage is compared with the case where the conductor is not divided. Can be reduced, the saliency is increased, and the accuracy of position detection is improved. Thereby, while being able to reduce a number of parts, cost can be reduced. Further, the size of the motor 35 can be reduced and the weight can be reduced. Furthermore, a highly reliable electric power steering device can be obtained.

  In such an electric power steering apparatus, cogging torque and torque ripple generated by the motor 35 are transmitted to the steering wheel 31 via the worm gear 33 and the column shaft 32. Therefore, when the motor 35 generates a large cogging torque or torque ripple, a smooth steering feeling cannot be obtained.

  On the other hand, the surface magnet type motors shown in the first to third embodiments, particularly, the rotation sensorless driving can be achieved while suppressing the cogging torque and the torque ripple, thereby obtaining a smooth steering feeling. Can do.

  Further, as described in the first embodiment, since the position detection accuracy can be ensured even if the amplitude of the high-frequency current is small, noise can be reduced. Therefore, application to a column type in which the motor 35 is disposed in the passenger compartment and the positions of the driver and the motor are close is also effective.

  DESCRIPTION OF SYMBOLS 1 Stator, 2 Stator core, 3 Armature winding part, 4 Rotor, 6 Rotor core, 7 Permanent magnet, 8 Conduction circuit part, 8a, 8b, 8e Axial direction conductor part, 8c, 8d, 8f, 8g Connection conductor part, 11 Permanent magnet type motor, 12, 34 Controller, 35 Motor.

Claims (9)

A stator having a stator core, an armature winding provided in the stator core, and a rotor having a rotor core and a plurality of permanent magnets provided in the rotor core. In the permanent magnet type rotating electrical machine,
The rotor is provided with a conduction circuit portion that is a closed circuit,
The conduction circuit portion includes a plurality of axial conductor portions provided along the axial direction of the rotor, and a plurality of connection conductor portions that connect the axial conductor portions.
The permanent magnet type rotating electrical machine is characterized in that the conductor constituting the conductive circuit portion is divided into a plurality of divided conductors when a cross section perpendicular to the length direction is viewed.   The permanent magnet type rotating electric machine according to claim 1, wherein the axial conductor portion and the connecting conductor portion are arranged so as to individually surround the permanent magnets. The axial conductor portions are respectively disposed between the adjacent permanent magnets,
2. The permanent magnet type rotation according to claim 1, wherein the connection conductor portion is a pair of annular conductors connecting between the end portions of all the axial conductor portions at both axial end portions of the rotor. Electric. When the frequency of the high-frequency current injected into the armature winding is fh [Hz], the conductivity is σ [S / m], and μ is the magnetic permeability [H / m],

The conductor of the conductive circuit section is divided so that the thickness dimension of the divided conductor in the radial direction of the rotor is smaller than the skin depth δ [m] expressed by The permanent magnet type rotating electrical machine according to any one of claims 1 to 3. When the frequency of the high-frequency current injected into the armature winding is fh [Hz], the conductivity is σ [S / m], and μ is the magnetic permeability [H / m],

The conductor of the axial conductor portion is divided so that the thickness dimension of the divided conductor in the circumferential direction of the rotor is smaller than the skin depth δ [m] represented by The permanent magnet type rotating electrical machine according to any one of claims 1 to 3.   The permanent magnet type rotating electrical machine according to any one of claims 1 to 3, wherein the conductor constituting the conduction circuit portion is divided in a radial direction of the rotor.   The permanent magnet type rotating electrical machine according to any one of claims 1 to 3, wherein the conductor constituting the axial conductor portion is divided in a circumferential direction of the rotor.   The permanent magnet type rotating electric machine according to any one of claims 1 to 5, wherein the conduction circuit unit is configured by bundling a plurality of strands as the divided conductors. The permanent magnet type rotating electrical machine according to any one of claims 1 to 8,
And a controller that drives the permanent magnet type rotating electrical machine as a permanent magnet type motor and superimposes a high frequency voltage on the voltage for driving the permanent magnet type motor and applies the high frequency voltage to the permanent magnet type motor. Electric power steering device.

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