JP3687622B2 - Method for detecting rotor position of rotating electrical machine - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a stator in which a plurality of electromagnets each having a coil wound around a tooth of a stator piece are provided apart from each other in the circumferential direction, and rotates adjacent to at least one of the radially outer side and the inner side of the stator. The position of the rotor is detected in order to generate smooth rotor rotation by synchronously controlling the current flowing in the coils of each electromagnet of a rotating electrical machine having a rotor having a plurality of permanent magnets that are freely supported and spaced apart from each other in the circumferential direction. It is about how to do.
[0002]
[Prior art]
As for rotor position detection in a conventional rotating electrical machine, there is one described in Japanese Patent Application Laid-Open No. 2000-14103, which, for example, rotates relative to the stator 14 of the rotating electrical machine 13 as shown in FIG. Position sensors 17A and 17B made of resolvers or encoders are provided in the inner rotor 15 and the outer rotor 16, respectively, and the position of the rotor is detected by counting the encoded pulses of these position sensors.
[0003]
In contrast to the magnetic field generated by the plurality of permanent magnets provided in the rotor 15 or 16, the magnetic field generated by the electromagnet in the vicinity of each permanent magnet is attracted and repelled by controlling the current flowing through the plurality of electromagnetic coils in the stator 14. However, if the relative position of the permanent magnet with respect to the electromagnet is not known, it is not possible to know at which timing and in what phase the current should flow through each electromagnet of the stator 14. 16 smooth rotations cannot be obtained. Therefore, in the rotating electrical machine, it is necessary to detect the position of the rotor in order to obtain smooth rotation of the rotor regardless of whether or not speed control is performed.
[0004]
[Problems to be solved by the invention]
However, in the conventional rotor position detection method, since it is necessary to add a position sensor comprising a pulse transmission unit and a pulse reception unit such as an encoder to the shaft end of the rotor, it is necessary to secure a mounting space for the position sensor. However, there was a problem that it might increase in size.
[0005]
Further, a sensorless detection method for estimating the position of the rotor by using a current to be applied to the electromagnetic coil of the stator or a voltage generated by the energization is also conceivable, but in addition to a normal 1 stator / 1 rotor motor, FIG. In the case of a 1-stator / 2-rotor composite rotor type rotating electrical machine as shown, there is a problem that the description of the model becomes complicated and the calculation time for estimating the position increases, making it unsuitable for high-speed rotation.
[0006]
Accordingly, an object of the present invention is to provide a rotation that does not require an individual position sensor, and does not require an electric circuit and a calculation process for estimating the rotor position with a current flowing through a stator electromagnetic coil or a voltage generated by the current flowing. There is a method for detecting the rotor position of an electric machine.
[0007]
[Means for Solving the Problems]
In order to achieve this object, the rotor position detecting method of the present invention according to the first aspect of the present invention is such that a rod member made of a magnetic material is disposed between stator pieces adjacent to the rotor, and the magnetic field of the permanent magnet in the rotor is rotated during the rotor rotation. The rotor position is detected based on the eddy current generated in the magnetic material rod member under the influence of the above.
[0008]
【The invention's effect】
According to the first aspect of the present invention, the magnetic material rod member is disposed between at least one pair of stator pieces adjacent to each other in the circumferential direction, and the position of the rotor is determined by detecting the eddy current flowing through the rod member. Since detection is possible, there is no need to provide a position sensor that increases the size both in the axial direction and in the radial direction as in the prior art, and the rotating electrical machine can be simplified and miniaturized.
[0009]
According to the second aspect of the present invention, one end of both ends in the axial direction of the bar member made of a magnetic material is grounded, and the other end is connected to an impedance lower than the internal impedance of the bar member. Thus, an electric circuit is formed, and a current or voltage generated in the electric circuit is measured as a rotor position signal.
[0010]
According to the third aspect of the present invention, in the case of a rotating electrical machine having n permanent magnet magnetic pole pairs of a rotor driven by m phase electromagnets in the stator, the stator coils have the same phase. The rotor position is detected by averaging measured rotor position signals for at least two, and at most n, rod members of magnetic material corresponding to the electromagnetic coil. According to this configuration, more accurate rotor position detection is performed by eliminating the influence of errors and noises in detection signals of at least two (up to n) rod members that have the same phase and essentially the same output. be able to.
[0011]
According to the fourth aspect of the present invention, a stator core is formed by fastening a pair of retaining ring plates each having a stator piece formed by laminating thin plates arranged on both side ends in the axial direction, and the magnetic material A plurality of fastening members in which the pair of retaining ring plates are arranged at equal intervals in the circumferential direction to fasten the pair of retaining ring plates between the successive stator pieces circumferentially adjacent to each other on the side adjacent to the rotor Consists of bolts. According to this configuration, the bolt for assembling the stator core functions not only for the purpose of assembly but also as an eddy current induction medium for detecting the rotor position, so that a limited space can be used effectively.
[0012]
According to the fifth aspect of the present invention, the rotor is provided with a rotor on each of the radially outer side and the inner side of one stator, but in this case, the efficiency of the rotating electrical machine can be greatly improved. .
[0013]
According to the sixth aspect of the present invention, in the composite rotor type rotating electrical machine, the air gap between the yokes of the adjacent stator pieces on which the fastening bolts of the magnetic material are arranged is wide on the rotor side adjacent in the radial direction, Since the coil is narrowed on the coil side, it is possible to reliably eliminate the interference between the eddy currents of the bolts of the outer bolt train related to the position detection of the outer rotor and the eddy currents of the bolts of the inner bolt train related to the position detection of the inner rotor. .
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Next, preferred embodiments of the present invention will be described with reference to the drawings.
[0015]
FIG. 2 is a partial cross-sectional view of a composite rotor type rotating electrical machine having an inner rotor 15 and an outer rotor 16 that are coaxially and rotatably arranged on both the radially inner side and the outer side of a single stator 14. , Two permanent magnets 15A and 15B adjacent to each other constituting one magnetic pole pair of the inner rotor 15, and two permanent magnets 16A and 16B adjacent to each other constituting one magnetic pole pair of the outer rotor 16; The two adjacent stator pieces 18A and 18B of the stator 14 and the radially adjacent inner and outer rotors 15 and 16 between the stator pieces 18A and 18B, preferably adjacent to each other. Fastening bolts 19A and 19B as rod members of magnetic material arranged in a space formed by a notch formed at the opposite end of the yoke of the stator piece Shows a relationship.
[0016]
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 the laminated body of the thin plate stator pieces is arranged at both end portions in the axial direction are fastened with bolts. The stator core is configured by being fastened together by 19A and 19B. According to the present embodiment, these fastening bolts 19A and 19B are constituted by magnetic members.
[0017]
A leakage magnetic flux magnetic path 21A generated between the permanent magnets 15A, 15B of the inner rotor 15 adjacent to the stator 14 radially inward and the corresponding adjacent ends of the stator pieces 18A, 18B, and a radius with respect to the stator 14 The leakage magnetic flux magnetic path 21B generated between the permanent magnets 16A and 16B of the outer rotor 16 adjacent to the outer side in the direction and the stator pieces 18A and 18B is arranged in an air gap interposed between the leakage magnetic flux magnetic paths 21A and 21B. In such fastening bolts 19A and 19B, eddy currents are generated in the axial direction.
[0018]
Since the eddy current generated in the fastening bolts 19A and 19B is generated by a change in the magnetic flux passing through the bolt, the center position of the gap between the two permanent magnets 15A and 15B and 16A and 16B forming a pair of magnetic pole pairs, That is, the eddy current takes a peak value on the q axis. The peak value of the generated eddy current is detected, and by subtracting the phase shift from the d axis measured in advance from the detected phase, that is, the center position of the permanent magnets 15A, 15B and 16A, 16B, the permanent magnet of the rotor is subtracted. The position can be determined. This relationship is shown in FIG.
[0019]
In the embodiment of the composite rotor type rotating electrical machine shown in FIG. 2, notches (air gaps) formed at the opposing ends of the yokes of the adjacent stator pieces 18A and 18B on which the fastening bolts 19A and 19B made of magnetic material are arranged. Is widened on the rotor side adjacent in the radial direction and narrowed on the coil 18C side, thereby eliminating interference between the leakage magnetic flux magnetic paths 21A and 21B and ensuring that eddy currents generated in the fastening bolts 19A and 19B are free from noise. Can be detected.
[0020]
FIG. 4 is a plan view of the situation when a pair of magnetic pole pairs N and S by permanent magnets of two adjacent rotors pass through a set of stator pieces 1, 2 and 3 as three-phase electromagnets. Show.
[0021]
As shown in FIG. 4A, when the N pole of the first permanent magnet is approaching the fastening bolt 19-1 among the magnetic pole pairs in the rotor, the stator piece 1 includes the first pole in the rotor. An S pole attracting the N pole of the permanent magnet is generated in the T-shaped end yoke, and the N pole repelling the N pole of the first permanent magnet is formed in the T-shaped end yoke in the stator piece 2. Energize the electromagnetic coil in the direction of generation.
[0022]
On the other hand, as shown in FIG. 4B, when the N pole of the first permanent magnet in the rotor passes the fastening bolt 19-1, the stator piece 1 has the N pole of the first permanent magnet in the rotor. The repulsive N pole is generated in the T-shaped end yoke, and the stator coil 2 is energized by the electromagnetic coil in such a direction that the S pole repelling the S pole of the second permanent magnet in the rotor is generated in the T-shaped yoke. Do.
[0023]
Thus, due to the change of the magnetic field generated in the stator pieces 1 and 2, the fastening bolt 19-1 between the stator pieces 1 and 2 has a cycle between both side ends in the axial direction of the bolt (direction perpendicular to the drawing sheet). As a result, an eddy current whose direction is reversed is generated.
[0024]
As shown in FIG. 5, a method of detecting a potential difference of eddy currents generated in the fastening bolts and a method of detecting eddy currents flowing in the fastening bolts are used as methods of taking out a detection signal for position detection in the fastening bolts of magnetic material. Two methods are possible.
[0025]
When detecting the potential difference, as shown in FIG. 5A, copper electrodes 22 are embedded in the upper and lower surfaces of the bolt, and the tips of the electrodes are connected to the input side of the OP amplifier 23 having a high input impedance. Thereby, the potential difference corresponding to the eddy current pulse shown in FIG. 3 is amplified and detected.
[0026]
Also in the case of detecting the current, as shown in FIG. 5b, the OP amplifier 23 is still used, but a low resistance (current detection resistor) 24 having an impedance smaller than the internal impedance of the fastening bolt is connected in front of the OP amplifier. The current is caused to flow through the resistor 24 at 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 at the rear stage.
[0027]
As shown in FIG. 3, the eddy current flowing in the bolt changes in one cycle of electrical angle. For example, there are four permanent magnets of the outer rotor (four adjacent permanent magnet pairs in the circumferential direction). ) And each magnetic pole pair is driven in three phases (three magnetic coils of the stator correspond to one magnetic pole pair) (total number of permanent magnets of the rotor is 2 × 4 = 8, total of the electromagnetic coils of the stator 3 × 4 = 12), even if magnetic material rod members are arranged in all 12 dead spaces between the adjacent stator pieces at the outer and inner peripheral edges of the stator, the permanent magnets of the adjacent rotors The three electromagnets have different phases with respect to the eddy currents generated in the magnetic material rod member due to the influence of the above, but the remaining nine electromagnets are repeated in the previous three electromagnets. Therefore, it is only necessary to perform detection from one bar member out of 12 bar members made of magnetic material. Alternatively, only one of the twelve bar members having the same weight and the same volume may be used as the magnetic material, and only the detection of the one magnetic material from the bar member may be performed.
[0028]
As shown in FIG. 6 (a), in the case of a rotating electrical machine in which there are four pairs of rotor magnetic pole pairs in which the N pole and the S pole face the three-phase stator, the eddy current of the magnetic material rod member or the fastening bolts 1-12 The rotor position detection for the fastening bolts 1, 4, 7, 10 of the same phase should all be the same output, and the fastening bolts [1, 2, 3], [4, 5, 6], including three phases, The fastening bolts of the set [7, 8, 9] and [10, 11, 12] are sequentially shifted in phase by 120 °.
[0029]
Although only the rotor position detection in one of the fastening bolts [1 to 12] may be performed, in order to eliminate the influence of manufacturing tolerance and noise, the fastening bolt [1 having the same phase by the method shown in FIG. , 4, 7, 10] is preferably performed, and the rotor position is detected by averaging the measured rotor position signals (see FIG. 6B).
[0030]
In the illustrated embodiment, the rotor shows two rotating electric machines, but the present invention can also be applied to a rotating electric machine having one rotor. In the illustrated preferred embodiment, the fastening bolt is shown as the magnetic material rod member. However, the magnetic material rod member may be simply arranged.
[Brief description of the drawings]
FIG. 1 is a side view showing a partial cross section of a conventional rotating electric machine having a position sensor for detecting a rotor position.
FIG. 2 is an explanatory diagram for explaining a preferred embodiment of a rotor position detection method according to the present invention.
FIG. 3 is a graph showing changes in eddy current flowing through a magnetic material rod member (fastening bolt).
FIG. 4 is a plan view of a situation when a pair of magnetic pole pairs N and S by permanent magnets of two adjacent rotors pass through a set of stator pieces 1, 2 and 3 in a three-phase electromagnet. It is explanatory drawing shown.
5A is an explanatory diagram showing a method for detecting a potential difference of eddy current generated in a fastening bolt as a bar member made of a magnetic material, and FIG. 5B is an explanatory diagram showing a method for detecting a current of eddy current flowing in the fastening bolt. is there.
6A is a bar member or fastening member made of magnetic material arranged between a rotor having four magnetic pole pairs (total of eight) permanent magnets and a stator piece having a corresponding three-phase electromagnetic coil. Explanatory drawing which shows the relationship with a volt | bolt, (b) is explanatory drawing of the method of measuring the bar member or fastening bolt of a magnetic material which becomes the same phase, and averaging a measured value.
[Explanation of symbols]
1-12 Sequential magnetic material rod member (fastening bolt) between stator pieces
13 Rotating electric machine
14 Stator
15 Inner rotor
16 Outer rotor
17 Position sensor
18 Stator piece
18C coil
18D cutout
19 Fastening bolt (bar material of magnetic material)
20 Retaining ring or plate
21 Leakage magnetic flux magnetic path
22 electrodes
23 OP amplifier
24 Low resistance (current detection resistance)

Claims (6)

A stator in which a plurality of electromagnets each having a coil wound around the teeth of the stator piece are provided apart from each other in the circumferential direction, and is rotatably supported adjacent to at least one of the radially outer side and the inner side of the stator. In the method of detecting the position of the rotor of the rotating electrical machine having a rotor having a plurality of permanent magnets spaced apart from each other in the circumferential direction, a magnetic material rod member is disposed between the stator pieces adjacent to the rotor, A rotor position detection method for a rotating electrical machine, wherein a rotor position is detected based on an eddy current generated in a bar member of the magnetic material under the influence of a magnetic field of a permanent magnet in the rotor during rotor rotation. One end of both ends in the axial direction of the rod material is grounded, and the other end is connected to an impedance lower than the internal impedance of the rod member to form an electric circuit. A current generated in the electric circuit The method of claim 1, wherein the eddy current measurement is performed by measuring a voltage as a rotor position signal. In the case of a rotating electric machine having n permanent magnet pole pairs of a rotor driven by m phase electromagnets in the stator, at least of the rod members corresponding to the electromagnetic coils having the same phase among the electromagnetic coils of the stator 3. A method according to claim 1 or 2, wherein the rotor position is detected by averaging measured rotor position signals for two, at most n rod members. A stator core is formed by fastening a pair of retaining ring plates each having a stator piece formed by laminating thin plates arranged at both end portions in the axial direction, and the magnetic material rod member is disposed on the side adjacent to the rotor. 4. The structure according to claim 1, further comprising a plurality of fastening bolts arranged between the sequential stator pieces adjacent to each other in the circumferential direction so that the pair of holding ring plates are spaced apart from each other in the circumferential direction. The method according to any one of the above. 5. The method according to claim 4, wherein the rotating electrical machine is a synchronous motor having an outer rotor and an inner rotor that are rotatable about the same axis both on the radially outer side and the inner side of the stator. 6. The method according to claim 5, wherein an air gap between yokes of adjacent stator pieces on which the fastening bolts of the magnetic material are arranged is wide on the rotor side adjacent in the radial direction and narrowed on the coil side.

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