JP2002062162A - Magnetic pole position detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method which detects the magnetic pole positions of a multipolar rotor driving a polyphase stepping motor as a polyphase brushless DC motor and obtains a precise communication signal at low cost. SOLUTION: This magnetic pole position detector is characterized by that its detector rotor core is manufactured equivalently to a rotor part structure used for a hybrid type stepping motor to be detected and its stator main magnetic pole is manufactured equivalently to a stator part structure, and performs detection in the form of an electric signal by applying magnetic flux variation that the stator main magnetic pole has to a magnetic transducing element through a magnetism collection chip by using magnetic resistance variation depending upon how much the tip projection of the stator main magnetic pole facing the outer peripheral projection of the detector rotor core across a gap overlaps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for detecting a magnetic pole position of a multi-pole rotor for driving a multi-phase step motor as a multi-phase brushless DC motor.

[0002]

2. Description of the Related Art Conventionally, the rotational motion of a step motor is defined by the frequency of an input pulse to be commanded. However, when a large load is accelerated or the motor rotates at high speed, the rotational motion of the rotor can correctly follow the command pulse. The loss of synchronism causes a serious disadvantage that the rotation of the rotor is accompanied by abnormal vibration. In recent years, closed-loop driving of step motors has been adopted, but in many cases, only the conditions for occurrence of step-out are reduced, and many of them have not been solved in principle.

If the stepping motor can be operated as a brushless DC motor in order to avoid the step-out of the stepping motor described above, the advantages of both can be utilized, and stable rotation can be ensured even at the time of starting or a sudden load change.

[0004] In order to operate a step motor as a brushless DC motor, a commutation signal for detecting a magnetic pole position of a rotor and giving an appropriate energizing angle to a motor winding is required. Many methods have been proposed in which an encoder is directly connected to a hybrid type step motor shaft, an encoder signal is synchronized with a rotor magnetic pole position of the motor, and a commutation signal is used to operate as a brushless DC motor. Further, a method of detecting the position of the multi-pole rotor using an inexpensive Hall element as a commutation sensor instead of an expensive encoder is disclosed in Japanese Utility Model Laid-Open Publication No. Sho 57-34758, Japanese Utility Model Laid-Open Publication No. Sho 63-124083, It is proposed as in Japanese Unexamined Patent Publication No. 9-201206.

[0005]

To reduce the vibration of the motor, it is advantageous to make the step angle extremely small. However, when viewed as a brushless DC motor, the number of rotor magnetic poles becomes very large. For example, a three-phase step motor having a step angle of 0.6 ° corresponds to 200 poles. In order to operate as a DC brushless motor, it is necessary to accurately detect the position of the 200-pole rotor magnetic pole.

In the above-described step motor / encoder system, in order to use the encoder signal as a commutation signal, it is necessary to match the output pulse position of the encoder with the rotor magnetic pole position of the motor. However, when the number of magnetic poles is very large, the positioning accuracy of the mechanical angle between the rotor shaft of the motor and the encoder is not obtained. Further, it takes time to adjust even a motor having a relatively large step angle.

FIG. 8 shows the above-mentioned Japanese Patent Application Laid-Open No.
It is an outline of -174583 publication. A magnetic drum 101 in which the number of magnetic poles equal to the number of magnetic poles of the step motor 103 is applied to the outer periphery of the motor shaft 102 is fixed to the motor shaft 102.
The magnetic flux is collected by the two sensor cores 104 and 105 whose angles are shifted, and the Hall element 106 detects a change in magnetic flux. Even in this method, it is necessary to match the magnetic pole position of the magnetic drum 101 with the motor rotor magnetic pole position, and the problem of the mechanical angle positioning accuracy remains. Also, the positioning of the two magnetic members 107 and 108 is troublesome. Other devices, actual implementation 57-3475
8, Japanese Utility Model Application Laid-Open No. 63-124083, JP-A-9-20120
6 also requires an NS multi-pole magnet, as described above, and requires some form of alignment adjustment with the motor rotor. An object of the present invention is to solve the above-mentioned problems and to provide a magnetic pole position detector for obtaining an accurate commutation signal at low cost.

[0008]

SUMMARY OF THE INVENTION A magnetic pole position detector according to the present invention is manufactured to be equivalent to a rotor core equivalent to a rotor partial structure used for a hybrid type multi-phase stepping motor to be detected and to a stator partial structure. The stator main magnetic pole is opposed to the outer periphery protrusion of the rotor core via a gap. The change in magnetic flux generated in the stator main magnetic pole is applied to the magnetic transducer by utilizing the change in magnetic resistance due to the degree of overlap between the outer periphery of the rotor core and the tip protrusion of the stator main magnetic pole, and is detected as an electric signal.

When a Hall element is used as a magnetic transducer,
The magnetic force emerging from the rotor outer peripheral projection is a voltage output on which a DC voltage is superimposed because the rotor magnetic pole is a single pole. Since this superimposed voltage greatly changes depending on the temperature characteristics of the Hall element,
It is impossible to use it as it is as a rotor position sensor. Therefore, a method of arranging a second Hall element that is 180 ° out of phase by an electrical angle and comparing the output voltages of the first Hall element and the second Hall element as a reference, thereby removing an excessive superimposed voltage. Can be considered.

The components of the rotor of the motor and the rotor of the magnetic pole position detector are the same and can be easily held at the same angle with respect to the motor shaft. Further, the components of the stator of the motor and the main pole of the stator of the magnetic pole position detector are the same, and can be easily held at the same angle with respect to a certain reference point. As described above, the motor and the magnetic pole position detector can be positioned with high precision, and the adjustment work for matching the energized phase switching positions of the motor is not required.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of a magnetic pole position detector of the present invention mounted integrally with a motor. Part A is a magnetic pole position detector, and part B is a hybrid type step motor (hereinafter referred to as a motor). The rotor part structure of the motor at the part B has a single-pole structure between a first motor rotor core 12 having teeth on the outer periphery and a second motor rotor core 13 having inverted teeth on the outer periphery. The configuration is such that a magnetized motor permanent magnet 14 is sandwiched. Reference numeral 15 denotes a motor winding, and reference numeral 16 denotes a motor stator core on which the winding 15 is provided. 5 is a ball bearing for holding the motor rotation shaft 4, 11 is a motor housing, and 17 is a screw for assembling the motor.

In the magnetic pole position detecting section of section A according to the present invention, 1 is a detector permanent magnet which is unipolarly magnetized in the axial direction, 2
Is a detector rotor core having teeth-shaped protrusions on the outer periphery, 3
Is a rotor plate, a motor rotating shaft 4 and a detector permanent magnet 1
The rotor in which the rotor core 2 and the rotor plate 3 are fixed is a rotor. Reference numeral 6 denotes a stator main magnetic pole serving as a main magnetic pole of a detector stator core having irregularities of toothed protrusions on the inner periphery. Reference numeral 8 denotes a magnetic flux collection chip made of a magnetic material, 9 denotes a Hall element group for converting a magnetic field intensity into an electric signal, and 10 denotes a printed circuit board on which the Hall element group 9 is mounted. The detector rotor core of the magnetic pole position detecting section and the first motor rotor core 12 and the second motor rotor core 13 of the motor section are formed by pressing using the same mold, and have different thicknesses but identical planar shapes. Similarly, the stator main magnetic pole 6 of the magnetic pole position detecting unit and the motor stator core 16 of the motor unit are formed by pressing with the same mold, and have different thicknesses but the same planar shape.

FIG. 2 shows a three-phase magnetic pole position detector, in which a rotor composed of a detector rotor core 2 having teeth-shaped projections on the outer periphery and a tooth on the inner periphery of an annular detector stator core via a gap. 3 shows a positional relationship between a stator main magnetic pole 6 having projections and depressions and a Hall element group 9. Reference numeral 20 denotes an outer peripheral annular yoke of the detection stator core. In this figure, the number of magnetic poles of the stator main magnetic pole 6 is 12, and the position of the stator main magnetic pole is a.
~ L. Due to the rotation of the rotor, the above-described change in magnetic resistance of the air gap appears at an electrical angle of 60 ° behind b at the stator magnetic pole position a. Similarly, stator main magnetic pole positions c to
1 is sequentially delayed by 60 electrical degrees. Therefore, to detect the three-phase signals U, V, and W having a phase difference of 120 electrical degrees,
If the U-phase Hall element 9-u is arranged at the stator main magnetic pole position a, the V-phase Hall element 9-v is arranged at the stator main magnetic pole position c, and the W-phase Hall element 9-w is arranged at the stator main magnetic pole position e. Good.

FIGS. 3A and 3B show a magnetic flux loop from the permanent magnet 1 of the detector. The magnetic flux emitted from the permanent magnet 1 of the detector passes through the rotor plate 3 and on the main magnetic pole 6 of the stator. Is concentrated on the magnetic flux collecting chip 8 disposed at the position. Further, it passes through the first stator main magnetic pole 6 having a toothed projection at the inner peripheral end, passes through the outer peripheral toothed projection of the detector rotor core 2 through the gap, and returns to the detector permanent magnet 1. Further, the Hall element 9 is opposed to the rotor plate 3 on the magnetic flux collecting chip 8 via a gap. FIGS. 3-1 and 3-2 show a state in which the magnetic resistance of the air gap between the detector rotor core and the stator main magnetic pole is the smallest, and the magnetic resistance of the air gap changes according to the rotational movement of the magnetic disk. As a result, the intensity of the magnetic field applied to the Hall element 9 also changes greatly. FIG. 3-3 shows an integrated structure in which the stator main magnetic pole is manufactured in a laminated structure of magnetic steel sheets and the half-punch convex portion for lamination is used as a magnetic flux collecting chip, which can be easily assembled.

FIG. 4 shows a method of generating a U-phase commutation signal from the output voltage waveform of the Hall element 9-u. 41 is an output voltage waveform of the Hall element 9-u, 42 is a certain reference voltage, and 43 is a U-phase commutation signal. As described above, since the detector permanent magnet 1 is magnetized to a single pole, the output voltage waveform 41 is a waveform in which the DC voltage is superimposed. A commutation signal 43 is obtained by processing the output voltage waveform 41 and the reference voltage 42 by a comparison circuit.

However, the Hall element group 9 has poor temperature characteristics, and the output voltage greatly fluctuates due to a change in ambient temperature.
In FIG. 4, reference numeral 44 denotes an output voltage of the Hall element when the temperature changes, and reference numeral 45 denotes a commutation signal output from the comparison circuit. As described above, the duty ratio of H and L of the commutation signal changes depending on the temperature, thereby deteriorating the accuracy of commutation.

Therefore, as shown in FIG. 2, the first Hall element groups 9-u, 9-v, and 9-w of each phase have an electrical angle of 1 unit.
Second Hall element group 9-u ', 9-
v ′, 9−w ′ are arranged as shown in FIG. 2, and the output voltage of the first Hall element group and the output voltage of the second Hall element group of each phase are compared to remove an unnecessary superimposed voltage. It becomes possible.

FIG. 5 shows the generation of a U-phase commutation signal 43 from the intersection of the output voltage waveform 46 of the Hall element 9-u 'and the output voltage waveform 41 of the Hall element 9-u. The output voltage waveforms of the Hall elements are as shown by 44 and 47 with respect to the temperature change, but there is no change in the position of the intersection between the two, and the commutation signal 4 with respect to the temperature change.
The duty of No. 3 does not change.

FIG. 6 shows commutation signals for three phases.
Represents a W-phase commutation signal, and a phase difference signal having an electrical angle of 120 ° is generated.

In FIG. 1, when assembling the motor and the magnetic pole position detector, the first motor rotor core 12 and the outer peripheral tooth-shaped projections of the detector rotor core 2 are made to coincide with each other. The motor stator core 16 and the first stator main magnetic pole 6 are provided with irregularities on the inner peripheral teeth of the main magnetic pole 6, and the motor stator core main magnetic pole having U, V, and W phase windings and the Hall element 9-.
By arranging u, 9-v, and 9-w so as to match each other, the phase relationship between the induced voltage generated by the rotation of the motor and the commutation signal is as shown in FIG. Here, 43 is a U-phase commutation signal output, and 50 is a U-phase motor induced voltage waveform. As described above, the commutation signal obtained with respect to the induced voltage has a phase difference of 90 electrical degrees, and a phase shift process is performed in the motor drive circuit to determine an optimal energizing position and energize the motor winding.

In FIG. 3A, the outer periphery of the rotor plate 3 is located above the Hall element 9, and the outer periphery is provided with the same number of slits as the number of tooth-like projections at the tip of the detector rotor core 2. The amount of change in magnetic flux passing through the element 9 increases, and the detection accuracy increases.

Further, in the embodiment of the present invention, the detector rotor core and the motor rotor core, and the detector stator core and the motor stator core have been described as being the same mold press. However, the parts for the motor and the detector are different in size. It is needless to say that a similar shape can be used.

Further, in the present invention, it is needless to say that a two-phase motor having a phase difference of 90 ° electrical angle and a five-phase motor having a phase difference of 36 ° electrical angle can be applied similarly to the above-described embodiment of the three-phase motor. .

The features of the magnetic pole position detector of the present invention exemplified in the above embodiment will be enumerated. (A) The position of the magnetic pole of the polyphase hybrid type step motor can be detected at low cost with a Hall element. (B) The main parts of the magnetic pole position detector of the present invention are equivalent to the parts of the hybrid type stepping motor and are constructed at low cost. (C) By arranging a magnetic flux collecting tip on each stator main magnetic pole,
No magnetic path is formed between the stator main magnetic poles, and the magnetic flux concentrates on the Hall element, so that the accuracy as a commutation signal is good. (D) By additionally arranging a Hall element having an electrical angle of 180 ° in each phase and detecting the intersection of the Hall element outputs,
This is equivalent to zero-cross detection, and a commutation signal with high temperature accuracy can be obtained. (G) The main parts of the magnetic pole position detector of the present invention are equivalent to the parts of the hybrid type stepping motor, the assembly of the alignment is easy, and no work is required after the alignment with the motor induced voltage. (H) The electric components (Hall elements, ICs, resistors, etc.) according to the present invention are all arranged on a single printed circuit board, are easily connected, can be miniaturized, and can be built in the motor. (I) The magnetic pole position detector of the present invention has a simplified structure,
The position can be detected with high accuracy.

[0025]

As described in detail above, the magnetic pole position detector of the present invention can detect the magnetic pole position of the rotor when the hybrid type step motor having the small step angle is operated as a brushless DC motor at low cost and with low assembly cost. Good
The accuracy of position detection can be improved and can be realized with a simplified structure. Motors equipped with this magnetic pole position detector can reduce rotation unevenness, expand the operating range, and operate with high efficiency, greatly expanding the applications.

[0026]

[Brief description of the drawings]

FIG. 1 is a structural diagram of a three-phase magnetic pole position detector and a hybrid type step motor according to the present invention.

FIG. 2 is a plan structural view of a three-phase magnetic pole position detector according to the present invention.

FIG. 3 is a structural diagram showing a magnetic flux loop of the magnetic pole position detector according to the present invention.

FIG. 4 is an output voltage waveform diagram of the Hall element of the magnetic pole position detector according to the present invention.

FIG. 5 is an output voltage waveform diagram of a first Hall element and a second Hall element of the magnetic pole position detector according to the present invention.

FIG. 6 is a commutation signal diagram generated from the magnetic pole position detector according to the present invention.

FIG. 7 is a relationship diagram between a commutation signal diagram generated from the magnetic pole position detector according to the present invention and a motor induced voltage.

FIG. 8 shows a conventional magnetic pole position detector.

[Explanation of symbols]

A: Magnetic pole position detector B: Hybrid type step motor al: Indicates the main magnetic pole position of the stator 1 ... Permanent detector magnet 2 ... Detector rotor core 3 ... Rotor plate 4 ... Motor rotating shaft 5 ... Ball bearing 6 ... First stator main magnetic pole 8 ... Magnetic collecting chip 9 ... Hall element group 10 ... Printed circuit board 11 ... Motor housing 12 ... first motor rotor core 13 ... second motor rotor core 14 ... motor permanent magnet 15 ... motor winding 16 ... motor stator core 17 ... screw 20 ... annular yoke Part 41: Output voltage waveform of Hall element 9-u 42: Reference voltage 43: U-phase commutation signal 44: Output voltage waveform of Hall element 9-u due to change in ambient temperature 45: U-phase commutation signal due to ambient temperature change 46 ... Output voltage waveform of Hall element 9-u '47 ... Output voltage waveform of Hall element 9-u' due to ambient temperature change 48 ... V-phase commutation signal 49: W-phase commutation signal 50: Induced voltage waveform of U-phase motor winding 51: Output voltage waveform of Hall element 9-u 52: U-phase commutation signal 53: Ambient temperature Output voltage waveform of Hall element 9-u due to change 101 ... Magnetic drum 102 ... Motor shaft 103 ... Motor 104 ... First sensor core 105 ... Second sensor core 106 ... Hall element 107: first magnetic body 108: second magnetic body

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02K 37/04 501 H02P 8/00 303A // H02P 8/00 303 H02K 11/00 C (72) Inventor Shinji Shimizu 3-93, Aioicho, Kiryu-shi, Gunma Japan Servo Corporation Kiryu Plant (72) Inventor Yoji Unoki 3-93, Aioicho, Kiryu-shi, Gunma Japan Servo Corporation Kiryu Plant F-term (reference) 2F063 AA01 AA35 BA30 BC06 BD01 BD11 BD16 CA34 CA40 CB01 DA01 DA05 DD06 EA03 GA24 GA40 GA52 GA67 GA69 KA01 LA01 LA19 LA23 2F077 AA11 AA13 FF13 FF34 JJ02 JJ08 NN04 NN21 PP12 PP26 QQ07 VV02 VV33 5H09 CA02H01 BB02H01 A0211

Claims (10)

[Claims] 1. A permanent magnet magnetized with NS in the rotation axis direction is sandwiched between a rotor core having a plurality of tooth-shaped protrusions on its outer periphery and a circular rotor plate having a larger outer diameter than the rotor core and made of a magnetic material. A plurality of stator main magnetic poles, which are fixed to the rotating shaft and have a plurality of tooth-shaped protrusions at their ends through radial gaps on the outer periphery of the rotor core, and converge magnetic flux generated in the tooth-shaped protrusions, are connected to the annular yoke. A stator core is provided at equal intervals on the inner circumference, and a stator main magnetic pole and a rotor plate are arranged so as to face each other with a thrust gap in the axial direction. A magnetic pole position detector characterized by detecting the position of a detector rotor core by detecting a change in magnetic flux passing through a stator main magnetic pole that changes in accordance with rotation of a rotor core. 2. The magnetic pole position detector according to claim 1, wherein a magnetic flux collecting tip made of a magnetic material is arranged in an axial direction of the magnetic transducer arranged in the thrust gap. 3. The magnetic resistance change of the radial gap due to the unevenness of the outer peripheral toothed projection of the rotor core and the unevenness of the toothed projection at the tip of the stator main pole becomes a phase difference every electrical angle of 60 °.
The number of stator main magnetic poles is 3n (n is an even number of 2 or more), and electrical angles of 60 °, 120 °, and 1 from the reference stator main magnetic pole.
The magnetic pole position detector according to claim 2, wherein six magnetic transducers are arranged in the thrust gap at positions of 80 °, 240 °, and 300 °. 4. The method of claim 1, wherein a change in magnetic resistance of the radial gap due to the unevenness of the outer peripheral tooth-shaped protrusion of the rotor core and the unevenness of the tooth-shaped protrusion at the tip of the stator main pole has a phase difference at every electrical angle of 90 °.
The number of stator main magnetic poles is 2n (n is an even number equal to or greater than 2), and the electrical angle is 90 °, 180 °, 2 ° from the reference stator main magnetic pole.
The magnetic pole position detector according to claim 2, wherein four magnetic transducers are arranged in the thrust gap at a position of 70 °. 5. The method of claim 1, wherein a change in magnetic resistance of the radial gap due to the unevenness of the outer peripheral tooth-shaped protrusion of the rotor core and the unevenness of the tooth-shaped protrusion at the tip of the stator main pole has a phase difference every electrical angle of 36 °.
The number of stator main magnetic poles is 5n (n is an even number of 2 or more), and electrical angles of 36 °, 72 °, 10 ° from the reference stator main magnetic pole.
8 °, 144 °, 180 °, 216 °, 252 °, 28
The magnetic pole position detector according to claim 2, wherein ten magnetic transducers are arranged in the thrust gap at positions of 8 ° and 324 °. 6. The method according to claim 3, wherein the electrical angle is 1
A magnetic pole position detector comprising a pair of magnetic transducers that differ by 80 °, and comparing output voltage waveforms of two magnetic transducers in the pair to detect a cross point. 7. The stator core according to claim 2, wherein the stator core is formed by laminating electromagnetic steel sheets, and the stator magnetic poles and the magnetic flux collecting chip are integrated by using the laminating half-punch convex portion as a magnetic flux collecting chip portion. Magnetic pole position detector. 8. The magnetic transducer according to claim 1, wherein the magnetic transducer is arranged on a single printed circuit board, and an electronic component for an output processing circuit of the magnetic transducer is mounted in a gap between the stator magnetic poles. Item 7. A magnetic pole position detector according to items 1 to 7. 9. A magnetic pole position detector, wherein the magnetic pole position detector according to claim 1 is integrated with a motor. 10. The magnetic pole position according to claim 1, wherein the outer periphery of the circular rotor plate is set to be on the magnetic transducer, and the outer periphery of the rotor plate is provided with the same number of toothed slits as the rotor core. Detector.