JP6485205B2 - Rotating electric machine - Google Patents

Description

  The present invention relates to a rotating electrical machine.

  In a rotating electrical machine, a fractional slot is employed to reduce cogging torque (for example, Patent Document 1).

JP 2012-44817 A

  However, when a fractional slot is used, the coil connection is concentratedly wound on the teeth of the stator core as compared with a general rotating electrical machine that is not a fractional slot (for example, a rotating electrical machine having a ratio of the number of poles to the number of slots of 2 to 3). Tends to be complicated, leading to an increase in coil end length and an increase in manufacturing costs.

  An object of the present invention is to provide a rotating electrical machine that can reduce cogging torque without using fractional slots.

According to the first aspect of the present invention, a stator having a cylindrical stator core, and a rotor having a rotor core disposed so that an outer peripheral side of the stator core faces each other via a gap are provided on the inner peripheral side of the stator core, A rotating electrical machine in which a coil is wound around a straight tooth formed between slots that are open on the inner peripheral surface and are arranged in the circumferential direction, and a flat permanent magnet is embedded in the rotor core. The number ratio is 2 to 3, one flat permanent magnet per pole , the width Wt of the end face of the straight teeth facing the flat permanent magnet, and the straight of the flat permanent magnet The gist is that the ratio Wt / Wm of the width Wm of the end face facing the teeth is 0.55 ≦ Wt / Wm ≦ 0.65.

According to the first aspect of the present invention, the ratio of the number of poles to the number of slots is 2: 3, one flat permanent magnet is provided per one pole, and is opposed to the flat permanent magnet of straight teeth. Since the ratio Wt / Wm of the end face width Wt and the end face width Wm facing the straight teeth of the flat permanent magnet is 0.55 ≦ Wt / Wm ≦ 0.65, a fractional slot is not used. Cogging torque can be reduced.

  In the invention described in claim 2, in the rotating electrical machine described in claim 1, 0.60 ≦ Wt / Wm ≦ 0.65 may be satisfied.

  According to the present invention, cogging torque can be reduced without using fractional slots.

The schematic diagram of the rotary electric machine in embodiment. The partial expansion schematic diagram of the rotary electric machine in embodiment. The figure which shows the measurement result of the cogging torque with respect to ratio Wt / Wm of width Wt of the straight teeth when the thickness of a flat permanent magnet is changed, and the width Wm of a flat permanent magnet. The figure which shows the measurement result of the cogging torque with respect to ratio Wt / Wm of width Wm of the straight teeth when the width of straight teeth is changed, and the width Wm of a flat permanent magnet.

  As shown in FIG. 1, a magnet-embedded rotary electric machine 10 includes a permanent magnet-embedded rotor (rotor) 20 and a stator (stator) 100. The stator 100 has a cylindrical stator core 101. The rotor 20 has a rotor core 30. The rotor core 30 is arranged so that the outer peripheral side thereof faces the gap G (see FIG. 2) on the inner peripheral side of the stator core 101. The rotating electrical machine 10 has “12” poles.

  As shown in FIGS. 1 and 2, 18 slots 102 are formed inside the stator core 101 in the circumferential direction. Each slot 102 opens to the inner peripheral surface of the stator core 101 and is arranged in parallel in the circumferential direction. Straight teeth 103 are formed between the slots 102. The straight teeth 103 are not provided with ridges, and the width Wt is constant.

  A coil (winding) 104 through which a three-phase alternating current is energized is wound around straight teeth 103 provided at equal intervals. The coil 104 is concentratedly wound around the straight teeth 103. As described above, the stator 100 is provided with the straight teeth 103 around which the coil 104 is wound on the inner peripheral side in parallel in the circumferential direction.

  The rotor core 30 is configured by laminating a plurality (for example, several tens) of substantially disc-shaped electromagnetic steel plates. A shaft (not shown) is inserted through the center of the rotor core 30. The rotor 20 is rotatably supported by a bearing of a housing (not shown) via a shaft in a state where the outer peripheral surface of the rotor core 30 is spaced from the straight teeth 103 by a predetermined distance.

  A permanent magnet embedded hole 31 is formed in the rotor core 30, and the permanent magnet embedded hole 31 extends in the axial direction. A flat permanent magnet 40 is inserted into the permanent magnet embedded hole 31. Specifically, one flat permanent magnet 40 is embedded in the rotor core 30 per pole in the circumferential direction. The flat permanent magnet 40 is formed in a flat plate shape having a rectangular cross section, and is magnetized in the thickness direction. In the present embodiment, the flat permanent magnet 40 is a rare earth permanent magnet.

  The flat permanent magnets 40 arranged in adjacent regions (one pole) are arranged so that the outer peripheral sides of the rotor 20 are different poles. For example, when a certain flat permanent magnet 40 is arranged so that the straight teeth 103 side becomes the S pole, the flat permanent magnet 40 arranged in the adjacent region (one pole) has the straight teeth 103 side as the N pole. It is arranged to become.

  The rotor core 30 is provided with flux barriers (holes) 32 and 33 so as to be continuous with the circumferential end of the permanent magnet embedded hole 31. The flux barriers 32 and 33 extend in the axial direction.

  In the stator 100, the number of slots per pole is “1.5” (the number of teeth per pole is “1.5”), and the angle θr from the center O per pole is 30 °. That is, the rotating electrical machine has the number of poles P = 2 and the number of slots S = 3, and the ratio of the number of poles P to the number of slots S is 2 to 3.

  The ratio Wt / Wm of the width Wt of the straight teeth 103 and the width Wm of the flat permanent magnet 40 is 0.55 ≦ Wt / Wm ≦ 0.65. More specifically, 0.60 ≦ Wt / Wm ≦ 0.65.

Next, the operation of the rotating electrical machine 10 configured as described above will be described.
When the rotating electrical machine 10 is driven, a three-phase current is supplied to the coil 104 of the stator 100, a rotating magnetic field is generated in the stator 100, and the rotating magnetic field acts on the rotor 20. Then, the rotor 20 rotates in synchronization with the rotating magnetic field by the magnetic attractive force and the repulsive force between the rotating magnetic field and the flat permanent magnet 40.

  The ratio Wt / Wm of the width Wt of the straight teeth 103 and the width Wm of the flat permanent magnet 40 is 0.55 ≦ Wt / Wm ≦ 0.65. More specifically, 0.60 ≦ Wt / Wm ≦ 0.65. Therefore, the cogging torque can be reduced.

Next, the measurement result of the cogging torque will be described with reference to FIG.
In FIG. 3, the horizontal axis represents the ratio Wt / Wm between the width Wt of the straight teeth 103 and the width Wm of the flat permanent magnet 40. In FIG. 3, the vertical axis represents the cogging torque. Further, as the flat permanent magnet 40, four types having a thickness tm of 4.0 mm, 4.5 mm, 5.0 mm, and 5.5 mm are used. The width Wt of the straight teeth 103 is fixed at 30 mm.

  In FIG. 3, it can be seen that the cogging torque is low in the range of 0.55 ≦ Wt / Wm ≦ 0.65. In particular, it can be seen that the cogging torque is lower in the range of 0.60 ≦ Wt / Wm ≦ 0.65. Note that the cogging torque can be reduced without decreasing the torque when the Wt / Wm is larger than when the Wt / Wm is large.

  As described above, in a 12-pole 18-slot rotary electric machine using straight teeth, the width of the flat permanent magnet 40 with respect to the width Wt of the straight teeth 103 is adjusted within an appropriate range, thereby reducing the cogging torque. Can be designed.

  Specifically, by adjusting the width Wt (Wt / Wm of 0.55 to 0.65) of the flat permanent magnet 40 of 46.1 mm to 54.5 mm with respect to the width Wt = 30 mm of the straight teeth 103, Cogging torque can be reduced. In particular, the cogging torque is adjusted by adjusting the width Wm (Wt / Wm is 0.60 to 0.65) of the flat permanent magnet 40 of 46.1 mm to 50 mm with respect to the width Wt = 30 mm of the straight teeth 103. It can be further reduced.

In FIG. 3, it can be seen that even when the thickness tm of the flat permanent magnet 40 is changed, the cogging torque can be reduced by designing at the same ratio.
In this way, it is possible to design a rotating electrical machine having a small cogging torque only by fine adjustment of the width Wm of the flat permanent magnet 40.

  In FIG. 4, the horizontal axis represents the ratio Wt / Wm between the width Wt of the straight teeth 103 and the width Wm of the flat permanent magnet 40. In FIG. 4, the vertical axis represents cogging torque. Moreover, as the flat permanent magnet 40, two types of straight teeth 103 having a width Wt of 23 mm and 30 mm are used. The flat permanent magnet 40 has a thickness tm of 4.5 mm and is fixed.

  As shown in FIG. 4, it can be seen that even if the width Wt of the straight teeth 103 is changed, the cogging torque is low in the range of 0.55 ≦ Wt / Wm ≦ 0.65. In particular, it can be seen that the cogging torque is lower in the range of 0.60 ≦ Wt / Wm ≦ 0.65.

  In addition, the use of fractional slots tends to complicate the connection of coils concentratedly wound on the teeth of the stator core, leading to an increase in coil end length and an increase in manufacturing cost. In this embodiment, the permanent magnet is not increased in size by using a rotating electrical machine that is not a fractional slot (a rotating electrical machine having a ratio of the number of poles to the number of slots of 2 to 3). Further, the connection of the coils concentratedly wound on the teeth of the stator core is not complicated, and an increase in coil end length can be avoided and an increase in manufacturing cost can be avoided.

According to the above embodiment, the following effects can be obtained.
(1) As a configuration of the rotating electrical machine, the ratio of the number of poles to the number of slots is 2 to 3, and one flat permanent magnet 40 is provided per pole. Further, the width Wm of the flat permanent magnet 40 is a fixed ratio with respect to the width Wt of the straight teeth 103. Specifically, the ratio Wt / Wm of the width Wt of the straight teeth 103 and the width Wm of the flat permanent magnet 40 is 0.55 ≦ Wt / Wm ≦ 0.65. As a result, the cogging torque can be reduced.

(2) In particular, when 0.60 ≦ Wt / Wm ≦ 0.65, the cogging torque can be further reduced.
The embodiment is not limited to the above, and may be embodied as follows, for example.

The rotary electric machine is a 12-pole 18-slot rotary electric machine, but is not limited thereto, and the ratio of the number of poles to the number of slots may be 2 to 3.

  DESCRIPTION OF SYMBOLS 10 ... Rotary electric machine, 20 ... Rotor, 30 ... Rotor core, 40 ... Flat plate permanent magnet, 100 ... Stator, 101 ... Stator core, 102 ... Slot, 103 ... Straight teeth, 104 ... Coil, G ... Gap.

Claims (2)

A stator having a cylindrical stator core;
A rotor having a rotor core arranged so that an outer peripheral side thereof faces through a gap on an inner peripheral side of the stator core;
With
A coil is wound around straight teeth formed between slots that are opened in the inner peripheral surface of the stator core and are arranged in the circumferential direction,
A rotating electric machine in which a flat permanent magnet is embedded in the rotor core,
The ratio of the number of poles to the number of slots is 2 to 3,
One flat permanent magnet per pole,
The ratio Wt / Wm of the width Wm of the end face facing the straight teeth of the plate-shaped permanent magnet and the width Wt of the opposite end faces the plate-shaped permanent magnet of the straight teeth,
0.55 ≦ Wt / Wm ≦ 0.65
A rotating electric machine characterized by 0.60 ≦ Wt / Wm ≦ 0.65
The rotating electrical machine according to claim 1, wherein: