JP2003299314A - Detecting method for rotor position of rotating electric machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a method for detecting the position of a rotor wherein a conventional position sensor having an encoder is obviated and a rotating electric machine is simplified and reduced in size. <P>SOLUTION: The rotating electric machine comprises a rotor 15 or 16 which is rotatably supported outside and/or inside a stator in the direction of the radius thereof. The rotor has a plurality of permanent magnets 15A and 15B or 16A and 16B away from each other in the circumferential direction. The method is for detecting the position of the rotor 15 or 16 to synchronously control currents flowing to coils 18c of individual electromagnets of the rotating elective machine having the rotor 15 or 16 and smoothly rotate the rotor. Rod members, preferably fastening bolts 19A and 19B, are placed in gaps which originally exist between at least one pair of stator pieces 18A and 18B. The stator pieces are adjacent to each other in the circumferential direction on a side where they adjoin to the rotor 15 or 16. Thus, eddy currents produced in the fastening bolts 19A and 19B by influences of the magnetic fields of the permanent magnets in the rotor when the rotor is rotated are measured as rotor position signals. Thus, conventional encoder-type position sensors are obviated. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stator in which a plurality of electromagnets each having a coil wound around a tooth of a stator piece are circumferentially spaced from each other, and a stator outer side and inner side in a radial direction. Smooth rotation of the rotor is achieved by synchronously controlling the currents flowing through the coils of the electromagnets of a rotating electric machine having a rotor having a plurality of permanent magnets that are rotatably supported adjacent to at least one of them and are separated from each other in the circumferential direction. Therefore, the present invention relates to a method for detecting the position of the rotor.

[0002]

2. Description of the Related Art A conventional rotor position detection in a rotary electric machine is disclosed in Japanese Patent Application Laid-Open No. 2000-14103, which is shown in FIG. Position sensors 17A and 17B, which are resolvers or encoders, are provided on the inner rotor 15 and the outer rotor 16 that rotate relative to each other.
Is provided and the position of the rotor is detected by counting the encoded pulses of these position sensors.

With respect to a magnetic field generated by a plurality of permanent magnets provided on the rotor 15 or 16, a magnetic field generated by an electromagnet near each permanent magnet is controlled by controlling a current flowing through a plurality of electromagnetic coils in the stator 14. Although the rotor is rotated by causing attraction and repulsion, if the relative position of the permanent magnet with respect to the electromagnet is not known, it is not known at which timing and in which phase the current should be applied to each electromagnet of the stator 14, Smooth rotation of the rotor 15 or 16 cannot be obtained. Therefore, in the rotating electric machine, it is necessary to detect the position of the rotor in order to obtain smooth rotation of the rotor regardless of the presence or absence of speed control.

[0004]

However, in the conventional rotor position detecting method, it is necessary to add a position sensor including a pulse transmitting portion and a pulse receiving portion such as an encoder to the shaft end of the rotor. However, there is a problem in that the mounting space must be secured, which may lead to an increase in size.

Further, a sensorless detection method in which the position of the rotor is estimated by using the current supplied to the electromagnetic coil of the stator or the voltage generated by the supplied current can be considered, but aside from the usual one-stator / one-rotor electric motor, In the case of a 1-stator / 2-rotor compound rotor type rotary electric machine as shown in FIG. 1, there is a problem that the model description becomes complicated and the calculation time for estimating the position increases, which makes it unsuitable for high-speed rotation.

Therefore, an object of the present invention is to eliminate the need for a separate position sensor and to provide an electric circuit and an arithmetic process for estimating the rotor position by the current applied to the electromagnetic coil of the stator or the voltage generated by the energization. There is a method of detecting the rotor position of a rotating electric machine that does not.

[0007]

To achieve this object, the rotor position detecting method according to the present invention according to the first aspect of the present invention is arranged such that a rod member made of a magnetic material is arranged between stator pieces adjacent to the rotor, and the rotor is rotated. At this time, the rotor position is detected based on the eddy current generated in the rod member made of the magnetic material under the influence of the magnetic field of the permanent magnet in the rotor.

[0008]

According to the first aspect of the present invention, a rod member made of a magnetic material is disposed between at least one pair of stator pieces circumferentially adjacent to each other, and an eddy current flowing in the rod member is detected. Since it is possible to detect the position of the rotor, there is no need to provide a position sensor that increases the dimension in the axial direction and the radial direction as in the related art, and the rotating electric machine can be simplified and downsized.

According to the second aspect of the present invention, one end of both axial ends of the rod member made of a magnetic material is grounded, and the other end is lower than the internal impedance of the rod member. The impedance is connected to form an electric circuit, and the current or voltage generated in the electric circuit is measured as a rotor position signal.

According to the present invention as set forth in claim 3, in the case of a rotating electric machine having n magnetic pole pairs of permanent magnets of a rotor driven by electromagnets of m phases in the stator, the same number of electromagnetic coils of the stator is used. The rotor position is detected by averaging the measured rotor position signals for at least two, and at most n, of the rod members made of magnetic material corresponding to the electromagnetic coils in phase. According to this configuration, at least two (n at the maximum) that should have the same phase and originally have the same output.
It is possible to detect the rotor position with higher accuracy by eliminating the error of the detection signal of each rod member and the influence of noise.

According to the fourth aspect of the present invention, a stator core is constructed by fastening a pair of holding ring plates, which are stator pieces formed by laminating thin plates at both ends in the axial direction, to each other. A plurality of bar members of the magnetic material are arranged at equal intervals in the circumferential direction for fastening the pair of retaining ring plates to each other between the successive stator pieces circumferentially adjacent to each other on the side adjacent to the rotor. It is composed of individual fastening bolts. According to this configuration, the bolt for assembling the stator core functions not only for the purpose of assembling but also as the eddy current inducing medium for detecting the rotor position, so that the limited space can be effectively used.

According to the fifth aspect of the present invention, the composite rotor type rotary electric machine is provided with rotors on the outer side and the inner side of one stator in the radial direction. In this case, the efficiency of the rotary electric machine is significantly improved. be able to.

According to a sixth aspect of the present invention, in a combined rotor type rotary electric machine, the air gaps between the yokes of adjacent stator pieces in which the fastening bolts of the magnetic material are arranged are adjacent to each other in the radial direction. Since it is wide on the coil side and narrow on the coil side, interference between the eddy current of the bolts of the outer bolt row related to the position detection of the outer rotor and the eddy current of the bolt of the inner bolt row related to the position detection of the inner rotor is reliably excluded. be able to.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will now be described with reference to the drawings.

FIG. 2 is a partial cross-sectional view of a combined rotor type rotary electric machine having an inner rotor 15 and an outer rotor 16 coaxially and rotatably arranged on both the inner side and the outer side of one stator 14 in the radial direction. And two permanent magnets 15A and 15B adjacent to each other which form one magnetic pole pair of the inner rotor 15, and two permanent magnets 16A adjacent to each other which form one magnetic pole pair of the outer rotor 16. And 16
B, two adjacent stator pieces 18A and 18B of the stator 14, and these stator pieces 18A
And 18B in the vicinity of the radially adjacent inner and outer rotors 15, 16 and preferably in the space created by the notches formed at the opposite ends of the yokes of the adjacent stator pieces. The relationship between the fastening bolts 19A and 19B as a rod member of the material is shown.

As shown in FIG. 2, the stator piece 18 of the stator 14 is formed by laminating thin plates, and a pair of holding ring plates in which laminated bodies of the thin plate stator pieces are arranged at both ends in the axial direction. Tighten the bolt 19
A and 19B are fastened together to form a stator core. According to this embodiment, these fastening bolts 19A,
19B is composed of a magnetic member.

The leakage flux magnetic path 21A generated between the permanent magnets 15A and 15B of the inner rotor 15 and the corresponding adjacent ends of the stator pieces 18A and 18B, which are radially inwardly adjacent to the stator 14, and the stator 14 are provided. On the other hand, the permanent magnets 16A of the outer rotor 16 adjacent to the outer side in the radial direction,
The leakage flux magnetic path 21B generated between the stator 16B and the stator pieces 18A, 18B is generated by the leakage flux magnetic path 21B.
Eddy currents are generated in the axial directions of the fastening bolts 19A and 19B arranged in the air gaps interposed between A and 21B.

The eddy currents generated in the fastening bolts 19A and 19B are generated by the change in the magnetic flux passing through the bolts, so that the two permanent magnets 15A and 15B forming one magnetic pole pair.
Center position of the gap between 16A and 16B, that is,
The eddy current has a peak value on the q-axis. The peak value of the generated eddy current is detected, and the d-axis measured in advance from the detected phase, that is, the permanent magnets 15A, 15B and 16A, 16B.
The position of the permanent magnet of the rotor can be determined by subtracting the phase shift from the center position of. This relationship is shown in FIG.

In the embodiment as the composite rotor type rotating electric machine shown in FIG. 2, fastening bolts 19A and 19 made of magnetic material are used.
Adjacent stator pieces 18A, 1 in which B is arranged
The notch (air gap) formed at the opposite end of the yoke 8B is wide on the rotor side adjacent in the radial direction, and
By narrowing on the 8C side, the leakage magnetic flux magnetic paths 21A, 2
It becomes possible to eliminate interference between 1B and reliably detect eddy currents generated in the fastening bolts 19A and 19B without noise.

FIG. 4 is a plan view of a situation in which a pair of magnetic poles N and S formed by permanent magnets of two rotors adjacent to each other passes through a set of stator pieces 1, 2 and 3 as a three-phase electromagnet. Expanded and shown.

As shown in FIG. 4A, when the N pole of the first permanent magnet of one magnetic pole pair in the rotor is approaching the fastening bolt 19-1, the stator piece 1
S that attracts the N pole of the first permanent magnet in the rotor
A pole is generated in the T-shaped end yoke, and the electromagnetic coil is energized in a direction in which the N pole repulsive to the N pole of the first permanent magnet is generated in the T-shaped end yoke in the stator piece 2. .

On the other hand, as shown in FIG. 4 (b), when the N pole of the first permanent magnet of the rotor has passed the fastening bolt 19-1, the stator piece 1 has the first permanent magnet of the rotor. An N pole that repels the N pole is generated in the T-shaped end yoke, and the stator piece 2 has a second pole in the rotor.
The electromagnetic coil is energized in the direction in which the S pole repelling the S pole of the permanent magnet is generated in the T-shaped yoke.

Due to the change in the magnetic field generated in the stator pieces 1 and 2 in this manner, the fastening bolts 19-1 between the stator pieces 1 and 2 have both end portions in the axial direction of the bolts (direction orthogonal to the plane of the drawing). An eddy current whose direction is periodically reversed between them is generated.

As shown in FIG. 5, a method of detecting the potential difference of the eddy current generated in the fastening bolt is used as a method of extracting the detection signal for detecting the position in the fastening bolt of the magnetic material.
There are two possible methods for detecting the eddy current flowing through the fastening bolt.

When detecting the potential difference, as shown in FIG. 5 (a), copper electrodes 2 are formed on the upper surface and the lower surface of the bolt, respectively.
2 is embedded and the tip of each electrode is connected to the input side of the OP amplifier 23 having high input impedance. As a result, FIG.
The potential difference corresponding to the eddy current pulse shown in is amplified and detected.

When detecting a current, as shown in FIG. 5b, the OP amplifier 23 is also used, but a low resistance (current detection resistance) 24 having an impedance smaller than the internal impedance of the fastening bolt is used. It is connected in parallel to the front stage so that a current flows through the resistor 24 in the front stage of the OP amplifier 23, and the potential difference generated on both sides of the resistor 24 is amplified and detected by the OP amplifier 23 in the rear stage.

As shown in FIG. 3, the eddy current flowing through the bolt changes with one electrical angle cycle, so that, for example, the permanent magnets of the outer rotor are arranged in four pole pairs (two adjacent permanent magnet pairs are arranged in the circumferential direction). There are four), and each magnetic pole pair is driven in three phases (one magnetic pole pair corresponds to three electromagnetic coils of the stator) (2 x 4 = 8 total permanent magnets of the rotor, The total number of coils is 3 × 4 = 12), and even if bar members made of magnetic material are arranged in all of the 12 dead spaces between the stator pieces that are successively adjacent to each other on the outer peripheral edge and the inner peripheral edge of the stator, the adjacent rotors are adjacent to each other. The three electromagnets have different phases with respect to the eddy currents generated in the rod member made of the magnetic material due to the effect of the permanent magnets, but the remaining nine electromagnets are repeated in the previous three electromagnets. Therefore, of the twelve bar members made of magnetic material, only one bar member needs to be detected. Alternatively, only one of the twelve bar members having the same weight and the same volume is used as the magnetic material, and the detection of the one magnetic material from the bar member is sufficient.

As shown in FIG. 6A, the N pole and the S pole are 3
In the case of a rotary electric machine having four rotor magnetic pole pairs facing the phase stator, a rod member or fastening bolts 1 to 1 made of a magnetic material.
Rotor position detection related to the eddy current of 2 should all be the same output for the fastening bolts 1, 4, 7, 10 of the same phase, and the fastening bolts [1, 2, 3], [4, including three phases
The phases of the respective fastening bolts of the set 5, 5, 6], [7, 8, 9], [10, 11, 12] are sequentially shifted by 120 °.

Although only the rotor position of one of the fastening bolts [1-12] may be detected,
To eliminate the effects of manufacturing tolerances and noise, the fastening bolts [1, 4, 7, 1] that have the same phase by the method shown in FIG.
0] for eddy current related detection,
It is preferable to average the measured rotor position signals to detect the rotor position (see FIG. 6B).

In the illustrated embodiment, the rotating electric machine has two rotors, but it can be applied to a rotating electric machine having one rotor. Further, although the fastening bolt is shown as the rod member made of the magnetic material in the illustrated preferred embodiment, the rod member made of the magnetic material may be simply arranged.

[Brief description of drawings]

FIG. 1 is a partial cross-sectional side view of a conventional rotating electric machine having a position sensor for detecting a rotor position.

FIG. 2 is an explanatory diagram illustrating a preferred embodiment of a rotor position detecting method according to the present invention.

FIG. 3 is a graph showing changes in eddy current flowing through a rod member (fastening bolt) made of a magnetic material.

FIG. 4 is a stator piece 1 of a three-phase electromagnet.
It is explanatory drawing which expand | deploys planarly and shows the condition when 1 set of magnetic pole pairs N and S by the permanent magnets of 2 rotors adjacent to each other passes through 2 and 3 sets.

5A is an explanatory diagram showing a method for detecting a potential difference of an eddy current generated in a fastening bolt as a rod member made of a magnetic material, and FIG. 5B is a diagram showing a method for detecting a current of an eddy current flowing in the fastening bolt. is there.

FIG. 6 (a) is a rod member or a fastening member made of a magnetic material arranged between a rotor having permanent magnets of four magnetic pole pairs (a total of eight) and a stator piece having a corresponding three-phase electromagnetic coil. FIG. 4B is an explanatory diagram showing a relationship with a bolt, and FIG. 6B is an explanatory diagram of a method of measuring a bar member or a fastening bolt made of a magnetic material having the same phase and averaging the measured values.

[Explanation of symbols]

1-12 Sequential magnetic rod members (fastening bolts) between stator pieces 13 Rotating electric machine 14 Stator 15 Inner rotor 16 Outer rotor 17 Position sensor 18 Stator piece 18C Coil 18D Notch 19 Fastening bolts (magnetic material rod member) 20 Retaining ring or plate 21 Leakage magnetic flux magnetic path 22 Electrode 23 OP amplifier 24 Low resistance (current detection resistance)

Claims (6)

[Claims] 1. A stator in which a plurality of electromagnets each having a coil wound around a tooth of a stator piece are circumferentially separated from each other, and adjacent to at least one of an outer side and an inner side of the stator in a radial direction. In a method for detecting the position of the rotor of a rotating electric machine having a rotor having a plurality of permanent magnets that are rotatably supported and spaced from each other in the circumferential direction, a rod of magnetic material is provided between the stator pieces adjacent to the rotor. Rotor position detection of a rotating electric machine, characterized in that members are arranged and the rotor position is detected based on an eddy current generated in a rod member of the magnetic material under the influence of a magnetic field of a permanent magnet in the rotor during rotor rotation. Method. 2. An electric circuit is formed by grounding one end of both axial end portions of the rod material and connecting the other end to an impedance lower than the internal impedance of the rod member. The method of claim 1, wherein the eddy current measurement is performed by measuring the current or voltage produced in the electrical circuit as the rotor position signal. 3. In the case of a rotary electric machine having n magnetic pole pairs of permanent magnets of a rotor driven by electromagnets of m phases in a stator, the rods corresponding to the electromagnetic coils of the same phase among the electromagnetic coils of the stator. At least two of the members
3. A method as claimed in claim 1 or 2 in which the measured rotor position signals for the at most n bar members are averaged to detect the rotor position. 4. A stator core is constructed by fastening a pair of retaining ring plates, each having a stator piece formed by laminating thin plates at both ends in the axial direction, together.
A plurality of bar members of the magnetic material are arranged at equal intervals in the circumferential direction for fastening the pair of retaining ring plates to each other between the successive stator pieces circumferentially adjacent to each other on the side adjacent to the rotor. The method according to any one of claims 1 to 3, wherein the method is constituted by individual fastening bolts. 5. The method according to claim 4, wherein the rotating electric machine is a synchronous electric motor having an outer rotor and an inner rotor rotatable about the same axis both radially outside and inside the stator. 6. The method according to claim 5, wherein the air gap between the yokes of adjacent stator pieces in which the fastening bolts of the magnetic material are arranged is wide on the rotor side and narrow on the coil side which are adjacent in the radial direction.