JP2016208780A - Field winding type rotating electrical machine - Google Patents

Abstract

A main object of a field winding type rotary electric machine is to improve the power factor at the time of high torque output and to improve the output efficiency at the time of low torque output.
A stator 30 having a stator coil 32, a rotor core 22a having a plurality of rotor teeth portions 26a arranged on the inner circumference of the stator 30 so as to be rotatable around the axis of the stator 30 and arranged in the circumferential direction; In a field winding type rotary electric machine 10 including a rotor coil 20 having a rotor coil 23 wound around a rotor tooth portion 26a, a rotor tooth portion is provided at a distal end portion 261a of the rotor tooth portion 26a in a circumferential direction of the rotor core 22a. A main salient pole 264a having a width narrower than the width of the root portion 263a of the head 26a and an auxiliary salient pole 265a having a width narrower than the width of the main salient pole 264a are provided.
[Selection] Figure 6

Description

  The present invention relates to a field winding type rotating electrical machine, and more particularly to the shape of a magnetic pole of a rotor.

  2. Description of the Related Art Conventionally, a rotor core of a field winding type rotary electric machine has a rotor tooth portion having a T-shaped cross section perpendicular to the axial direction. A field magnetic flux is generated by winding a field winding around the T-shaped rotor teeth and applying a DC voltage to the field winding (Patent Document 1).

JP 2010-166787 A

  When the rotor teeth portion is T-shaped, the magnetic flux is distorted by the q-axis inductance in the rotor core when the rotating electrical machine is driven. For this reason, a phase difference arises between the current and voltage flowing through the armature winding, and the power factor decreases. In a field winding type rotating electrical machine, the power factor is increased by increasing the current flowing through the field winding and increasing the field flux, or by changing the rotor core structure and reducing the q-axis inductance. Can be improved.

  Here, if the q-axis inductance is reduced by narrowing the area of the tip portion of the rotor teeth portion, the power factor improvement effect can be obtained, while the magnetic flux generated at the tip portion of the rotor teeth portion is reduced. Since the magnetic flux generated at the tip of the rotor teeth portion is reduced, there is a problem that the output efficiency of the torque with respect to the armature current is lowered particularly at the time of low torque output.

  The present invention has been made in view of the above problems, and in a field winding type rotary electric machine, the main object is to improve the power factor at the time of high torque output and to improve the output efficiency at the time of low torque output. To do.

  The present invention provides a stator (30) having an armature winding (32), and a plurality of rotor teeth portions arranged in the circumferential direction and rotatably provided around an axis of the stator on the inner periphery of the stator ( 26a, 26d) and a rotor (20) having a field winding (23) wound around the rotor teeth portion, a field winding type rotating electrical machine (10) ), The main salient poles (264a, 264d) having a width smaller than the width of the root portions (263a, 263d) of the rotor teeth portion in the circumferential direction of the rotor core at the tip portions (261a, 261d) of the rotor teeth portion. ) And auxiliary salient poles (265a, 265d) having a width narrower than the width of the main salient pole.

  When the current flowing through the armature winding is large and the magnetic flux is strong, the auxiliary salient pole is magnetically saturated. As a result, the q-axis inductance decreases, the phase of the voltage applied to the armature winding and the current flowing through the armature winding approaches, and the power factor can be improved. For this reason, the efficiency at the time of high torque output can be improved. Further, when the current flowing through the armature winding is small and the magnetic flux is weak, field magnetic flux is generated in both the main salient pole and the auxiliary salient pole, so that both the main salient pole and the auxiliary salient pole contribute to the torque. This makes it possible to output torque efficiently. Therefore, it is possible to improve the power factor at the time of high torque output and improve the output efficiency at the time of low torque output.

Sectional drawing containing the axis line which shows the whole structure of the traveling motor in a prior art. The partial sectional view perpendicular to the axial direction of the traveling motor in the prior art. The circuit diagram of the rotary electric machine apparatus in a prior art. The contour figure of the traveling motor in a prior art. The dq axis model figure of a field winding type rotary electric machine. The figure which shows the shape of a rotor core. The figure which shows the effect of the rotor core of 1st Embodiment. The figure which shows the shape of the rotor core of 2nd Embodiment.

(First embodiment)
DESCRIPTION OF EMBODIMENTS Hereinafter, an embodiment in which the present invention is embodied as a rotating electrical machine apparatus including a traveling motor for generating traveling power of a vehicle will be described.

  First, the structure of the traveling motor (field winding type rotating electrical machine) in the prior art will be described with reference to FIGS. As shown in FIG. 1, the traveling motor 10 according to the related art includes a housing 11, a rotor 20, and a stator 30.

  The rotor 20 includes a shaft 21, a rotor core 22, and a rotor coil 23 (field winding). The rotor core 22 is fixed to the shaft 21. The shaft 21 is rotatably supported by the housing 11 via a pair of bearings 12 and 13.

  The rotor coil 23 is connected to the field circuit 51 via a metal ring provided on the shaft 21 and a slip ring portion 15 including a brush that contacts the metal ring. A direct current voltage can be applied by 51. The field circuit 51 adjusts the field current If flowing in the rotor coil 23 by operating the DC voltage applied to the rotor coil 23 by stepping up and down the DC voltage input from the battery 50.

  A magnetic ring plate 24 is fixed to the shaft 21, and magnetic salient poles are provided on the outer periphery of the magnetic ring plate 24 at regular intervals. A rotational position sensor 14 is provided at a position facing the outer peripheral surface of the magnetic ring plate 24. The rotational position sensor 14 detects the rotational position of the rotor 20 by detecting the passage of the magnetic salient pole, and transmits the detection result to the controller 40.

  As shown in FIG. 2, a plurality of rotor coil housing grooves 25 are provided on the outer peripheral side of the rotor core 22 so as to penetrate in the axial direction of the rotor core 22. Rotor teeth portions 26 are arranged in the circumferential direction between the rotor coil housing grooves 25 adjacent in the circumferential direction. The outermost peripheral portion is provided with a flange portion 27 extending on both sides in the circumferential direction so as to narrow the rotor coil housing groove 25. A rotor coil 23 is wound around the rotor coil housing groove 25. The rotor coil 23 is wound in a square shape around the rotor tooth portion 26 so as to form a field magnetic flux φf. In addition, the winding method of the rotor coil 23 may be wound in a zigzag folded shape or the like in addition to the square shape.

  The stator 30 is disposed on the outer diameter side of the rotor 20. The stator 30 includes a stator core 31 and a stator coil 32 (armature winding). The stator core 31 has a cylindrical shape and is fixed to the inner peripheral wall surface of the housing 11. In other words, the rotor 20 is provided to be rotatable about the axis of the stator 30 on the inner periphery of the stator 30. On the inner peripheral side of the stator core 31, a plurality of slots 33 are provided penetrating in the axial direction of the stator core 31. A stator tooth portion 34 is formed between the slots 33 adjacent in the circumferential direction. The stator coil 32 is formed by three-phase coils U32, V32, and W32, and each phase coil U32, V32, and W32 is sequentially wound around the adjacent slot 33. Then, when a current flows through the stator coil 32, the stator teeth portion 34 is magnetized to form a magnetic salient pole.

  As shown in FIG. 3, the stator coil 32 is Y-connected by connecting a U-phase coil 32U, a V-phase coil 32V, and a W-phase coil 32W at a neutral point N. A booster circuit 60 and an inverter 70 (three-phase inverter) are connected between the battery 50 and the external lead terminals of the phase coils 32U, 32V, 32W. The inverter 70 has three upper arm elements 71 and three lower arm elements 72, and each arm element includes an IGBT 73 and a flywheel diode 74. Each arm element may be a MOS-FET.

  The inverter 70 is connected to the battery 50 via the booster circuit 60. The booster circuit 60 is for boosting the first voltage V1 input from the battery 50 to the second voltage V2. The booster circuit 60 of the present embodiment is a booster chopper type booster circuit 60 in which energy is accumulated in the inductor 62 when the booster switch 61 is turned on and is released through the diode 63 when the switcher is turned off. In the present embodiment, the first voltage V1 is set to 200V, and the second voltage V2 is set to 600V. That is, the booster circuit 60 boosts the first voltage V1 to the second voltage V2 that is three times higher. The voltage boosted by the booster circuit 60 is input to the inverter 70.

  The controller 40 acquires the rotational position information of the rotor 20 from the rotational position sensor 14. Then, the inverter 70 is intermittently controlled so as to energize the stator coil 32 with an armature current I (synchronous current) corresponding to the rotational position of the rotor 20, and the field circuit 51 is controlled so as to adjust the field current If. Torque is generated in the rotor 20 by intermittently controlling the inverter 70 in correspondence with the rotational position of the rotor 20.

  FIG. 4 shows a contour diagram (contour map) of magnetic flux density in the case of having the rotor core 22 in the prior art. In FIG. 4, the magnitude of the magnetic flux density is represented by the density of light and shade and contour lines. A portion having a high color density and a portion having a narrow interval between contour lines are portions having a high magnetic flux density, and a portion having a low color density and a portion having a wide interval between contour lines are portions having a low magnetic flux density.

  In FIG. 4, the rotor 20 rotates counterclockwise. The rotor core 22 is a soft magnetic material, and the magnetic flux φ is concentrated in a portion having a low magnetic resistance inside the rotor teeth portion 26. Specifically, the magnetic flux φ is concentrated on the front side in the rotation direction of the rotor 20 in the collar portion 27 of the rotor teeth portion 26. As a result, in the rotor 20, the magnetic flux φ advances from the d-axis to the q-axis direction, and the magnetic flux φ contributing to the torque decreases.

  FIG. 5 illustrates the phase difference between the armature current I and the armature voltage V in the dq axis model. If the contribution of the d-axis current Id is sufficiently small, the q-direction component of the armature voltage V is ω · φf, the d-direction component is ω · Lq · Iq, and the magnitude (absolute value) is ω · φ. The phase difference between the armature voltage V and the armature current I is θ, and cos θ corresponds to the power factor. By making cos θ close to 1, the output torque can be increased. Here, by reducing the q-axis inductance Lq that is the inductance in the q-axis direction, the voltage component (ω · Lq · Iq) due to the q-axis magnetic flux of the armature voltage V can be reduced, and cos θ can be made close to 1. . Therefore, the q-axis inductance Lq is reduced by changing the shape of the rotor core 22.

  The shape of the rotor core that reduces the q-axis inductance Lq is shown in FIG. The tip portions 261b and 261c of the rotor teeth portions 26b and 26c of the rotor cores 22b and 22c in FIGS. 6B and 6C are narrower than the root portions 263b and 263c on the yoke side of the rotor teeth portions 26b and 26c. It is provided as follows.

  Specifically, a taper 264b is provided in a region where the end surface of the tip portion 261b of the rotor teeth portion 26b of the rotor core 22b and the side surface of the side wall portion 262b shown in FIG. 6B intersect. Moreover, the side wall part 262b is provided in a planar shape, and the interval between the two side wall parts 262b is constant. In addition, at the tip portion 261c of the rotor teeth portion 26c of the rotor core 22c shown in FIG. 6C, L-shaped notches 264c are provided at both ends in the circumferential direction so as to extend in the axial direction. Moreover, the side wall part 262c is provided in a planar shape, and the interval between the two side wall parts 262c is constant.

  When the tip portions 261b and 261c are narrower than the root portions 263b and 263c like the rotor teeth portions 26b and 26c, the q-axis inductance Lq is reduced, so that the q-axis magnetic flux component (Lq · Iq) can be reduced. For this reason, θ approaches 0 and the power factor (cos θ) is improved.

  Here, at the time of low torque output, since the q-axis current Iq is small, the q-axis direction component of the magnetic flux φ and the voltage component of the armature voltage V due to the q-axis magnetic flux are small. For this reason, even if the q-axis inductance Lq is not decreased, the power factor cos θ approaches 1 if an appropriate d-axis magnetic flux component can be secured. Further, at the time of low torque output, if the structure of the rotor teeth part is configured to reduce the q-axis inductance Lq as shown in FIGS. 6B and 6C, the field generated at the tip part of the rotor teeth part. Since the magnetic flux is reduced, there arises a problem that the torque is reduced.

  That is, when the torque output is low, it is desirable that the width of the tip portion of the rotor tooth portion is wide in the circumferential direction of the rotor cores 22b and 22c, and when the torque output is high, the width of the tip portion of the rotor tooth portion is desirably narrow. I can say that. Therefore, the inventor of the present application has conceived the structure of the rotor core 22a shown in FIG.

  6A, the tip 261a of the rotor teeth portion 26a of the rotor core 22a is provided with a main salient pole 264a at the center and an auxiliary salient pole 265a at both ends in the circumferential direction of the rotor core 22a. In other words, a U-shaped notch (groove having a rectangular cross section) is provided in the distal end portion 261a of the rotor tooth portion 26a so as to extend in the axial direction in the vicinity of both end portions in the circumferential direction of the rotor core 22a. Moreover, the side wall part 262a is provided in a planar shape, and the interval between the two side wall parts 262a is constant in the circumferential direction of the rotor core 22a.

  The width of the main salient pole 264a is narrower than the root portion 263a of the rotor teeth portion 26a in the circumferential direction of the rotor core 22a. The auxiliary salient pole 265a has a narrower width than the main salient pole 264a in the circumferential direction of the rotor core 22a. More specifically, the width of the auxiliary salient pole 265a is set to approximately 1/15 of the main salient pole 264a. Further, in the circumferential direction of the rotor core 22a, the main salient pole 264a and the auxiliary salient pole 265a are provided within the range of the width of the root portion 263a. Further, in the radial direction of the rotor core 22a, the length of the main salient pole 264a and the length of the auxiliary salient pole 265a are substantially the same.

  The rotor core 22a made of a soft magnetic material is magnetically saturated at a predetermined saturation magnetic flux density. Since the magnetic saturation depends on the cross-sectional area of the magnetic path through which the magnetic flux φ passes, if the amount of the magnetic flux φ is the same, the smaller the cross-sectional area of the magnetic path, the easier the magnetic saturation occurs. For this reason, at the tip 261a of the rotor tooth portion 26a, the auxiliary salient pole 265a having a small cross-sectional area causes magnetic saturation with a smaller amount of magnetic flux φ than the main salient pole 264a having a large cross-sectional area. That is, when the armature current I flowing through the stator coil 32 reaches a predetermined value, the width of the auxiliary salient pole 265a in the circumferential direction of the rotor core 22a is set so that the auxiliary salient pole 265a is magnetically saturated, and the main salient pole 264a The width of the main salient pole 264a in the circumferential direction of the rotor core 22a is set so as not to cause magnetic saturation.

  When magnetic saturation occurs, the magnetic permeability of the auxiliary salient pole 265a becomes substantially equal to the permeability of the vacuum, and becomes extremely smaller than the permeability of the main salient pole 264a. Since the magnetic resistance is inversely proportional to the magnetic permeability, the magnetic resistance of the auxiliary salient pole 265a is extremely larger than the magnetic resistance of the main salient pole 264a, and the magnetic flux φ does not easily flow through the auxiliary salient pole 265a. Therefore, when the magnetic flux φ is large, that is, when the torque is high, the leading end portion 261a of the rotor core 22a in FIG. 6A becomes the leading end portion 261c of the rotor core 22c in FIG. 6C due to the magnetic saturation of the auxiliary salient pole 265a. Is equivalent to

  Further, when the magnetic flux φ is small, that is, when the torque is low, no magnetic saturation occurs in the auxiliary salient pole 265a. For this reason, the field magnetic flux φf is generated in both the main salient pole 264a and the auxiliary salient pole 265a, so that more field magnetic flux φf is generated as compared with the rotor core 22c in FIG. 6C. For this reason, when the torque is low, the torque can be generated efficiently.

  In the following description, the rotor core 22a in FIG. 6A is referred to as “the rotor core of the present embodiment”, the rotor core 22 in FIG. 2 is referred to as “Comparative Example 1”, and the rotor core 22b in FIG. The rotor core 22c of 6 (c) is referred to as “Comparative Example 3”.

  When the armature current I is set to the maximum value, the torques in the case of using Comparative Examples 1 to 3 and the rotor core of the present embodiment are compared. When the torque of Comparative Example 1 is 1, the torque of Comparative Example 2 is 1.12, the torque of Comparative Example 3 is 1.10, and the torque of the present embodiment is 1.13.

  FIG. 7 shows torques generated in the comparative example 3 and the present embodiment when three types of armature current I are supplied. Here, the torque of Comparative Example 1 is set to 1.

  When the armature current I is small (so that magnetic saturation does not occur in the auxiliary salient pole 265a), the torque in this embodiment is 1.01 and the torque in Comparative Example 3 is 0.98. Further, when the armature current I is medium (the degree at which magnetic saturation at the auxiliary salient pole 265a starts to occur), the torque of the present embodiment is 1.02 and the torque of Comparative Example 3 is 0.99. When the armature current I is large (the degree that the auxiliary salient pole 265a is completely magnetically saturated), the torque of the present embodiment is 1.07 and the torque of the comparative example is 1.06.

  Thus, when the armature current I is large, the rotor core 22a of the present embodiment has a higher torque due to the power factor improvement effect than the rotor core 22 having the T-shaped rotor teeth portion 26 of Comparative Example 1. Can be output. Further, when the armature current I is small and medium, the rotor core 22a of the present embodiment has an area of the tip portion 261a of the rotor tooth portion 26a as compared with the rotor core 22c having the convex teeth of the comparative example 3. As the field magnetic flux φf contributing to the torque increases and increases, a high torque can be output.

  The effects of this embodiment will be described below.

  When the armature current I is large, the auxiliary salient pole 265a is magnetically saturated. As a result, the q-axis inductance Lq decreases, the phases of the armature voltage V and the armature current I (= Iq) approach, and the power factor can be improved. For this reason, the efficiency at the time of high torque output can be improved. Further, when the armature current I is small, the field magnetic flux φf is generated in both the main salient pole 264a and the auxiliary salient pole 265a, so that both the main salient pole 264a and the auxiliary salient pole 265a contribute to the torque. This makes it possible to output torque efficiently. Therefore, it is possible to improve the power factor at the time of high torque output and improve the efficiency at the time of low torque output.

  Since the main salient pole 264a and the auxiliary salient pole 265a are provided within the width of the root portion 26da in the circumferential direction of the rotor core 22a, in the step of winding the rotor coil 23 around the rotor tooth portion 26a, the rotor coil 23 Can be prevented from interfering with the main salient pole 264a and the auxiliary salient pole 265a.

  In the radial direction of the rotor core 22a, the length of the main salient pole 264a and the length of the auxiliary salient pole 265a are substantially the same. For this reason, the distance between the main salient pole 264a and the stator teeth portion 34 (magnetic salient pole) is equal to the distance between the auxiliary salient pole 265a and the stator teeth portion 34. Thereby, the field magnetic flux φf generated in the auxiliary salient pole 265a effectively contributes to the output torque.

(Second Embodiment)
FIG. 8 shows a cross-sectional view of the rotor core 22d of this embodiment. The rotor core 22d rotates only in one direction (counterclockwise). One main salient pole 264d and one auxiliary salient pole 265d are provided at the tip 261d of the rotor teeth portion 26d of the rotor core 22d of the present embodiment. Moreover, the side wall part 262d is provided in a planar shape, and the interval between the two side wall parts 262d is constant. The auxiliary salient pole 265d is provided only in front of the main salient pole 264d in the rotational direction. In other words, the front end portion 261d is provided with a U-shaped notch (groove with a rectangular cross section) at the front end in the rotational direction so as to extend in the axial direction, and an L-shape at the rear end in the rotational direction. The notch (step) is provided so as to extend in the axial direction.

  The width of the main salient pole 264d is narrower than the root portion 263d of the rotor teeth portion 26d in the circumferential direction of the rotor core 22d. The auxiliary salient pole 265d has a narrower width than the main salient pole 264d in the circumferential direction of the rotor core 22d. More specifically, the width of the auxiliary salient pole 265d is set to approximately 1/15 of the main salient pole 264d.

  Further, the main salient pole 264d and the auxiliary salient pole 265d are provided within the range of the width of the root portion 263d in the circumferential direction of the rotor core 22d. In the radial direction of the rotor core 22d, the length of the main salient pole 264d and the length of the auxiliary salient pole 265d are substantially the same.

  The magnetic flux φ generated by the stator coil 32 is mainly generated in the q-axis direction. That is, the magnetic flux φ is generated in the advance direction with respect to the field magnetic flux φf. For this reason, when the electric current which flows into the stator coil 32 is small, the part ahead of the rotation direction of the rotor teeth part 26d mainly contributes to a torque. That is, even when the auxiliary salient pole 265d is provided only in the front, it is possible to efficiently output torque when the current flowing through the stator coil 32 is small.

(Other embodiments)
In the above configuration, a current is passed from the field circuit 51 to the rotor coil 23. It is good also as a structure which changes this and produces the electric current which flows into the rotor coil 23 using the magnetic flux which a stator coil 32 produces | generates.

  The main salient poles 264a and 264d and the auxiliary salient poles 265a and 265d may be provided outside the range of the width of the root portions 263a and 263d in the circumferential direction of the rotor cores 22a and 22d.

  In the radial direction of the rotor cores 22a and 22d, the length of the main salient poles 264a and 264d may be different from the length of the auxiliary salient poles 265a and 265d.

  -In the rotor teeth part 26d of 2nd Embodiment, it is good also as a structure which abbreviate | omits the L-shaped notch (step) provided in the edge part of the rotation direction back.

  DESCRIPTION OF SYMBOLS 10 ... Traveling motor, 20 ... Rotor, 22a, 22d ... Rotor core, 23 ... Rotor coil (field winding), 26a, 26d ... Rotor teeth part, 30 ... Stator, 32 ... Stator coil (armature winding), 261a , 261d ... tip portion, 263a, 263d ... root portion, 264a, 264d ... main salient pole, 265a, 265d ... auxiliary salient pole.

Claims (6)

A stator (30) having an armature winding (32);
A rotor core (22a, 22d) having a plurality of rotor teeth portions (26a, 26d) arranged in the inner periphery of the stator so as to be rotatable about the axis of the stator and arranged in the circumferential direction; A rotor (20) having a wound field winding (23);
In a field winding type rotating electrical machine (10) comprising:
Main salient poles (264a, 264d) having a width narrower than the width of the root portions (263a, 263d) of the rotor teeth portion in the circumferential direction of the rotor core at the tip portions (261a, 261d) of the rotor teeth portion; A rotating electrical machine comprising an auxiliary salient pole (265a, 265d) having a width narrower than the width of the main salient pole.   The rotating electrical machine according to claim 1, wherein the main salient pole and the auxiliary salient pole are provided within a width range of the root portion in a circumferential direction of the rotor core.   3. The rotating electrical machine according to claim 1, wherein a length of the main salient pole and a length of the auxiliary salient pole are substantially the same in a radial direction of the rotor core. The rotor rotates in only one direction,
The auxiliary salient pole (265d) is provided only in front of the main salient pole (264d) in the rotational direction of the rotor. Rotating electric machine.   The width of the auxiliary salient pole in the circumferential direction of the rotor core is set so that the auxiliary salient pole is magnetically saturated when the armature current flowing through the armature winding becomes a predetermined value, and the main salient pole is magnetic. 5. The rotating electrical machine according to claim 1, wherein a width of the main salient pole in a circumferential direction of the rotor core is set so as not to be saturated.   5. The rotating electrical machine according to claim 1, wherein a width of the auxiliary salient pole is set to approximately 1/15 of a width of the main salient pole in a circumferential direction of the rotor core. .