JP2000060038A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor which can maintain an reverse salient pole property, even at a maximum current application. SOLUTION: The sides of poles 18 of a stator 12 which are parallel with a motor shaft are C-chamfered. One pole 22 of a rotor 14 is formed of two permanent magnets 20 which are arranged into a V-shape. A pole gap 26 is provided between the two permanent magnets 20 arranged into a V-shade. In each salient pole 24 between the poles 22 of the rotor, a salient pole gap 28, whose width is approximately equal to the width of the salient pole, is provided near the circumference of the rotor. With this constitution, an inverse salient pole property, i.e., a q-axis inductance Lq larger than a d-axis inductance Ld, can be realized over the entire range from zero current to the maximum current and as a result, the rotating angle of the rotor can be detected in accordance with an inductance change.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor having a permanent magnet disposed on a rotor.

[0002]

2. Description of the Related Art There is known a permanent magnet motor in which magnetic poles in which permanent magnets are arranged and salient poles made of a soft magnetic material are alternately arranged in the circumferential direction of a rotor. Permanent magnet motors are known for their advantages of being compact and capable of achieving high output.

As a method of controlling the speed of an electric motor, there is known a method of detecting a rotation angle of a rotor and supplying a current to a coil of a stator in accordance with the detected rotation angle. Generally, a configuration such as a resolver is added to a rotor shaft to detect the rotation angle. In this case, a new configuration is added to the electric motor, which causes a problem such as an increase in the number of parts.

[0004]

SUMMARY OF THE INVENTION The d-axis and q of the motor
The inductances Ld and Lq relating to the axis are values obtained by superimposing a DC component on the relationship between the rotational positions of the rotor and the stator, that is, an AC component that changes depending on the phase. That is, it has an AC component that changes at a cycle of (360 ° / number of poles). If the change (AC component) of the inductances Ld and Lq is detected, the rotational position of the rotor can be detected. The DC component changes depending on the current flowing through the coil of the stator. In addition, these inductances L
The phases of d and Lq are inverted. Detection of a change in inductance can be measured by measuring a current generated in response to a pulse voltage applied to the coil.

When the current is not flowing or small, the q-axis inductance Lq is larger than the d-axis inductance Ld (Ld <Lq), and the detected current is
It is governed by changes in the q-axis inductance Lq. Ld <
The characteristic of Lq is called reverse saliency. As the current increases, the inductances Ld and Lq decrease under the influence of magnetic saturation, but the rate of decrease differs between the d-axis inductance and the q-axis inductance. There is a current value at which the q-axis inductance Lq changes more greatly with respect to the current change, so that the q-axis inductance Lq is substantially equal to the d-axis inductance Ld (Ld = Lq). In this case, as described above, the inductance L
Since d and Lq have inverted phases, they cancel each other out and cannot detect a current change for detecting the rotor rotation angle. Further, when the current increases, the d-axis inductance Ld increases (Ld> Lq).
That is, the phase of the current change is inverted. Therefore,
Under the condition of Ld ≧ Lq, there is a problem that the detection of the rotor rotation angle based on the inductance change as described above cannot be performed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problem, and has as its object to provide a permanent magnet motor having a reverse saliency even when the current increases.

[0007]

In order to solve the above-mentioned problems, a motor according to the present invention has magnetic poles on which permanent magnets are arranged and salient poles made of a soft magnetic material alternately arranged in the circumferential direction. And a stator having magnetic poles arranged in a circumferential direction, the rotor having the following rotor and stator. That is, the rotor is provided with a salient pole gap substantially equal to the width of the salient pole in the salient pole, and in the magnetic pole, two permanent magnets are arranged in a V-shape with both ends facing the outer periphery of the rotor, A magnetic pole gap is provided between two permanent magnets. On the other hand, the stator has a chamfer provided on a side of the magnetic pole parallel to the axis of the electric motor.

Even when the current increases, the change in inductance can be detected because the reverse saliency, that is, the q-axis inductance Lq is greater than the d-axis inductance Ld.

[0009]

Embodiments of the present invention (hereinafter referred to as embodiments) will be described below with reference to the drawings. FIG. 1 shows a quarter cross section of the stator 12 and the rotor 14 of the electric motor 10 according to the present embodiment. The radius r _{S of the} stator 12 is 145.0 mm, and the radius r _{R of the} rotor 14 is 9
0.0 mm. The coil 16 has a height of 21.25 m
m, the number of turns is 10.5 turns. Pole 18 of the stator is formed by an electromagnetic steel sheet to be described later, its width is defined by the dimension W _S illustrated. The gap between the stator 12 and the rotor 14 is 0.7 mm. As shown, two permanent magnets 20 of neodymium are arranged in a V-shape on the rotor 12 such that both ends face the outer periphery of the rotor, thereby forming a magnetic pole 22 of the rotor.
The circumferential width of the rotor surface of the rotor magnetic pole 22 is defined by the dimension W _M which open width or shown in V-shape. Portion between the rotor poles 22 are salient poles 24, defined by a dimension W _T illustrating the circumferential width at the rotor surface.

A side of the stator pole 18 parallel to the motor axis is chamfered, and the size of the chamfer is defined by a chamfer width C. Stator 12 and rotor 14
Are composed of laminated magnetic steel sheets, and the characteristics of the magnetic flux density with respect to the magnetizing force of the magnetic steel sheets are shown in FIG. Further, between the permanent magnets 20 arranged in a V shape, that is, V
A magnetic pole gap 26 is provided at the bottom of the V-shape. A salient pole gap 28 substantially equal to the width of the salient pole is also provided near the rotor periphery of the salient pole.

FIGS. 3 and 4 show the motor shown in FIG. 1 having a stator magnetic pole width W _S of 27.1 mm, a rotor magnetic pole width W _M of 39.1 mm, a salient pole width W _T of 29.3 mm and a chamfer width. The inductances Ld and Lq when the current is 0 and the maximum current when C is 13.0 mm are shown. When the current is 0 (FIG. 3), the q-axis inductance Lq is large. Even at the maximum current (FIG. 4), both the d-axis and q-axis inductances Ld and Lq decrease, but the magnitude relationship is maintained.
Therefore, in the electric motor of the present embodiment, the reverse saliency, that is, Ld <Lq, is maintained in the entire operation range. Therefore, it is possible to detect the rotor rotation angle based on this inductance change without the inductance change relating to the rotor rotation angle disappearing or the phase being inverted.

FIG. 5 shows a schematic configuration of a motor 110 as a comparison object of the present embodiment. Motor 110
In the first embodiment, the magnetic poles 118 of the stator 114 are not chamfered, and the magnets 120 of the rotor 114 are also not arranged in a flat plate in a V-shape. The specifications such as the rotor radius and the stator radius are the same as those of the electric motor 10 shown in FIG. This electric motor 11
As shown in FIG. 6, the d-axis inductance Ld is dominant in the inductance at the maximum current in the case of 0. In this case, as described above, the detection of the rotor rotation angle based on the inductance change cannot be performed.

In the electric motor 110 shown in FIG. 1, the stator magnetic pole width W _S , the rotor magnetic pole width W _M , the salient pole width W _T and the chamfer width C are set to the values shown in FIG. Also maintained the reverse saliency. The common features at this time are (1) that the stator poles are chamfered, (2) that there is a gap 24 over the entire width of the salient poles, and (3) that the permanent magnets 20 are arranged in a V-shape. And (4) having a gap 26 at the bottom of the V-shaped arrangement between the permanent magnets 20.

[Brief description of the drawings]

FIG. 1 is a quarter sectional view schematically showing an electric motor according to the present embodiment.

FIG. 2 is a magnetic characteristic diagram of an electromagnetic steel sheet used for the electric motor of the present embodiment.

FIG. 3 is a diagram illustrating a change in inductance with respect to a rotor rotation angle at a current of 0 according to the embodiment;

FIG. 4 is a diagram illustrating a change in inductance with respect to a rotor rotation angle at the time of a maximum current according to the embodiment;

FIG. 5 is a schematic configuration diagram of a motor of a comparative example of the present embodiment.

6 is a diagram showing a change in inductance of the comparative example of FIG. 5;

FIG. 7 is a view showing an example of each dimension of the electric motor of the present embodiment.

[Explanation of symbols]

10 motor, 12 stator, 14 rotor, 16
Coil, 18 stator poles, 20 permanent magnet, 22
Rotor magnetic pole, 24 salient ,, 26 pole gap, 28 salient poles gap, W _S theta pole width, W _M rotor pole width, W _T
Salient pole width, C chamfer width.

Continuation of the front page (72) Inventor Eiji Yamada 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Co., Ltd. F-term (reference) 5H611 BB01 BB08 QQ07 5H621 AA03 BB07 GA01 GA04 GA14 GA15 GA20 5H622 AA03 CA02 CA07 CA10 CA14 CB03 CB05 DD02 PP03 PP11 PP17

Claims (1)

[Claims] An electric motor comprising: a magnetic pole on which permanent magnets are arranged; a rotor in which salient poles made of a soft magnetic material are alternately arranged in a circumferential direction; and a stator in which magnetic poles are arranged in a circumferential direction. The salient pole has a salient pole gap substantially equal to the salient pole width. In the magnetic pole, two permanent magnets are arranged in a V-shape with both ends facing the outer periphery of the rotor. An electric motor in which a magnetic pole gap is provided between two permanent magnets, wherein the stator is provided with a chamfer on a side parallel to an axis of the electric motor of the magnetic pole.