JP2005020810A - Polyphase motor control unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small polyphase motor control unit and capable of precisely detecting rotational angle. <P>SOLUTION: A three-phase brushless DC motor is equipped with a rotational angle sensor 4 of a Hall effect 120° arrangement method. The rotational angle sensor 4 substitutes three angular voltages for a prescribed mathematical expression whose variables are the angular voltages outputted from three galvano-magnetic devices 41, for numerical calculation to extract three angular signals where an offset voltage is canceled. Thus, a small rotational angle sensor realizes precision detection of angular signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multiphase motor control device that detects a rotor position using a Hall element.
[0002]
[Prior art]
Information on a rotation angle (also simply referred to as an angle) by detecting a magnetic field generated from a rotating magnetic field source and changing in accordance with the angle by a magnetoelectric conversion element (hereinafter simply referred to as a Hall element). A multi-phase motor control device that detects angle information) and performs switching control of a motor current based on the angle information is widely used in, for example, brushless DC motors. This multiphase motor control device is equipped with a Hall element equal to the number of phase coils constituting the stator coil in order to control switching of each phase voltage applied to each phase terminal of the motor. The phase angle between the angular voltage output by the Hall element and the corresponding phase voltage of the stator coil is preferably constant even if the pair of Hall element and phase voltage changes. Are arranged such that the circumferential angular pitch between the Hall elements corresponds to an angle obtained by dividing the electrical angle 2π by the number of phases. Therefore, in the three-phase brushless DC motor, the three Hall elements are arranged in an angle range of electrical angle 4π / 3. Hereinafter, this conventional angle detection device may be referred to as a Hall element 240 degree arrangement method. The output (angle voltage) of these Hall elements is the DC offset when the magnetic field is present in addition to the magnetic flux of the magnet that is the magnetic field generation source (for example, leakage magnetic flux from the rotor). Voltage (also simply referred to as an offset voltage), and an angle detection error corresponding to the offset voltage occurs. For this reason, Patent Document 1 proposes to obtain an angle signal in which the offset voltage is canceled by extracting the difference between these three Hall element output voltages (angle voltages). Hereinafter, this offset voltage cancellation method is also referred to as an interphase angle voltage extraction method.
[0003]
In addition, the conventional Hall element 240 degree arrangement method described above has a large circumferential width of the angle detection device, which increases the size of the angle detection device, leading to an increase in cost, and the flow of air for cooling the motor is also deteriorated. There was a problem of letting. For this reason, Patent Document 2 discloses that in a three-phase brushless DC motor, a W-phase Hall element is placed between a U-phase Hall element and a V-phase Hall element that are spaced apart by an electrical angle of 2π / 3 in the circumferential direction. Propose to arrange. Hereinafter, this angle detection device may be referred to as a Hall element 120-degree arrangement method.
[0004]
[Problems to be solved by the invention]
If the above-described Hall element 120-degree arrangement method and the phase angle voltage extraction method described above are employed at the same time, it is expected that a highly accurate and small angle detection device for a brushless DC motor can be realized. However, according to the study of the present inventor, in order to cancel the offset voltage included in the output voltage of the three Hall elements arranged by the Hall element 120 degree arrangement method, the above-described phase angle voltage extraction method is applied. Even so, I realized that the cancellation of the offset voltage was not as successful as in the case of the Hall element 240 degree arrangement method. That is, it was found that the Hall element 120-degree arrangement method described above and the offset voltage cancellation by the interphase angle voltage extraction method are not compatible. Therefore, if the angle detector is miniaturized by the Hall element 120-degree arrangement method, it is impossible to eliminate the possibility of abnormal motor current conduction due to an offset error.
[0005]
The present invention has been made in view of the above problems, and an object of the present invention is to provide a small-sized multiphase motor control device capable of detecting a rotation angle with high accuracy.
[0006]
[Means for Solving the Problems]
A multi-phase motor control device according to a first aspect of the present invention is fixed to a rotating shaft of a multi-phase motor having a stator having three or more phase coils and a rotor rotating to face the stator at predetermined angular intervals and alternately with polarity. The rotating magnetic pole part and the rotating magnetic pole part facing each other at a predetermined distance and spaced apart from each other by a predetermined angle in the circumferential direction are arranged on the housing side of the multi-phase motor and are adjusted to the magnitude of the magnetic field of the rotating magnetic pole part. An angle detection unit including first, second, and third magnetoelectric conversion elements that outputs an angle voltage having a correlation, and an angle signal including information on the angle of the rotation shaft based on each angle voltage. An angle signal processing unit that extracts the number of elements, and a stator current control unit that performs switching control of a current to be supplied to each phase coil based on each angle signal, and the second magnetoelectric conversion element includes: In the output by the first multi-phase motor control device is arranged such that the opposite direction to the output of the third magneto-electric conversion element,
By calculating the numerical value by substituting the three angular voltages into a predetermined mathematical expression using the angular voltages output by the first, second, and third magnetoelectric transducers as variables, the angular signal processing unit. The three angle signals from which the offset voltage is canceled are extracted. In this way, highly accurate angle signal detection can be realized by a small rotation angle sensor.
[0007]
In the configuration according to claim 2, in the multiphase motor control device according to claim 1, the angle signal processing unit further includes three phase voltages applied to each phase terminal of a three-phase brushless DC motor as the multiphase motor. Output the three angle signals having a predetermined phase angle, and the first magnetoelectric transducer outputs the angle voltage corresponding to the phase angle of the U-phase voltage of the three phase voltages. The second magnetoelectric conversion element is separated from the first magnetoelectric conversion element by one electrical angle π / 3 in the circumferential direction, and corresponds to the phase angle of the −W phase voltage among the three phase voltages. The angle voltage is output, and the third magnetoelectric conversion element is separated from the first magnetoelectric conversion element by an electrical angle of 2π / 3 in a predetermined direction in the circumferential direction. The angle voltage corresponding to the phase angle is output. ing.
[0008]
In this way, the rotation angle of the three-phase brushless DC motor can be detected with high accuracy by a small rotation angle sensor.
[0009]
According to a third aspect of the present invention, in the multiphase motor control device according to the first or second aspect, the angle signal processing unit further changes the angular voltage output from the first, second, and third magnetoelectric transducers. The offset voltage is extracted by substituting the three angle voltages into a predetermined mathematical formula, and the three angle signals are extracted by subtracting the offset voltage from the angle voltage. It is said. In this way, the offset voltage superimposed on the angle voltage of each phase can be canceled by a simple calculation.
[0010]
According to a fourth aspect of the present invention, in the multiphase motor control device according to the first or second aspect, the angle signal processing unit further inverts the angular voltage output from the second magnetoelectric conversion element to obtain an angle of the W phase. The three angle signals from which the offset voltage has been canceled are extracted by calculating voltages and calculating the interphase voltages of the U, V, and W phase angle voltages. In this way, the offset voltage superimposed on the interphase angle voltage can be canceled by a simple calculation.
[0011]
According to a fifth aspect of the present invention, in the multiphase motor control device according to the third and fourth aspects, the angle signal processing unit further supplies a current to be supplied to the phase coils using the angle signal according to the third aspect. The first control mode for switching control and the second control mode for switching control of the current to be supplied to each phase coil using the angle signal according to claim 4 are detected based on the angle signal. It is characterized by switching according to the rotation speed of the motor. In this way, the advance angle can be accurately switched by a simple process, and the offset voltage can be canceled by a small rotation angle sensor.
[0012]
The multi-phase motor control device according to the second aspect of the invention is fixed to the rotating shaft of a multi-phase motor having a stator having three or more phase coils and a rotor that rotates facing the stator at predetermined angular intervals and alternately with polarity. The rotating magnetic pole part and the rotating magnetic pole part facing each other at a predetermined distance and spaced apart from each other by a predetermined angle in the circumferential direction are arranged on the housing side of the multi-phase motor and are adjusted to the magnitude of the magnetic field of the rotating magnetic pole part. An angle detection unit including first, second, and third magnetoelectric conversion elements that outputs an angle voltage having a correlation, and an angle signal including information on the angle of the rotation shaft based on each angle voltage. An angle signal processing unit that extracts the number of elements, and a stator current control unit that performs switching control of a current to be supplied to each phase coil based on each angle signal, and the second magnetoelectric conversion element includes: In the output by the first multi-phase motor control device is arranged such that the opposite direction to the output of the third magneto-electric conversion element,
The first, second and third magnetoelectric transducers are formed by the same process on the same substrate and are formed integrally with the angle signal processing unit. This makes it possible to simplify the manufacturing process without increasing the size of the rotation angle sensor composed of the angle detection unit and the angle signal processing unit, and greatly reduce the variation in distance between the magnetoelectric transducers, thereby increasing the angle with high accuracy. Detection can be realized.
[0013]
A multi-phase motor control device according to a third aspect of the present invention is fixed to a rotating shaft of a multi-phase motor having a stator having three or more phase coils and a rotor that rotates against the stator at predetermined angular intervals and alternately with polarity. The rotating magnetic pole part and the rotating magnetic pole part facing each other at a predetermined distance and spaced apart from each other by a predetermined angle in the circumferential direction are arranged on the housing side of the multi-phase motor and are adjusted to the magnitude of the magnetic field of the rotating magnetic pole part. An angle detection unit including first, second, and third magnetoelectric conversion elements that outputs an angle voltage having a correlation, and an angle signal including information on the angle of the rotation shaft based on each angle voltage. In a multiphase motor control device comprising: an angle signal processing unit that extracts the number of elements; and a stator current control unit that performs switching control of a current to be supplied to each phase coil based on each angle signal.
The angle signal processing unit extracts an angle signal corresponding to an angular voltage output from the first, second, and third magnetoelectric transducers at less than a predetermined number of rotations, and the first signal at the predetermined number of rotations or more. An angle signal corresponding to an interphase angular voltage, which is a difference between two angular voltages among the angular voltages of the first, second, and third magnetoelectric transducers, is extracted. In this way, the advance angle switching can be realized accurately by a simple process.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The multi-phase motor control apparatus of the present invention will be specifically described by the following examples.
[0015]
(Example 1)
Hereinafter, an embodiment of the present invention will be described with reference to FIG. 1 which is a schematic cross-sectional view in the axial direction. Reference numeral 1 denotes a three-phase brushless DC motor, which is a field coil type synchronous machine, having a Landel rotor 2, a stator 3 surrounding the rotor 2, a rotation angle sensor 4, and a housing 5 to which the stator 3 is fixed. . Reference numeral 6 denotes a brush device that supplies power to the field coil of the rotor 2 through the slip ring 7, and 8 denotes a rotating shaft that is rotatably supported by the housing 5 with the rotor 2 fixed thereto. Since this type of three-phase brushless DC motor itself is well known, further explanation is omitted.
[0016]
Next, the rotation angle sensor 4 that characterizes this embodiment will be described.
[0017]
This rotation angle sensor 4 adopts the Hall element 120-degree arrangement method described above, and is fixed to the housing 5 with a disk-shaped rotating magnetic pole portion 40 fixed to the rotating shaft 8 and a Hall element 41 built-in. And a detecting unit 42. The detector 42 faces the rotating magnetic pole 40 in the axial direction. α / 2 is an angle between adjacent Hall elements 41 and 41, and is set to an electrical angle of 60 degrees, that is, π / 3 in a three-phase brushless DC motor. R is a radius from the axial center to the position of the Hall element 41. In the rotating magnetic pole part 40, permanent magnet parts equal to the number of rotor magnetic poles are alternately arranged in the circumferential direction.
[0018]
The Hall element 41 has a Hall effect semiconductor portion having Hall effect characteristics and a circuit portion that amplifies the voltage of the Hall effect semiconductor portion and outputs it as an angular voltage. Although this circuit part is a semiconductor chip formed integrally with the Hall effect semiconductor part, it is naturally possible to arrange the Hall effect semiconductor part and the circuit part separately.
[0019]
An important feature of the Hall element 120-degree arrangement method shown in FIG. 2 is that the center Hall element 41 is arranged in the opposite direction to the two Hall elements 41 on both sides. In this way, the output voltage of the center Hall element 41 is opposite to that of the two Hall elements 41 on both sides. That is, when the output voltage in the magnetic field 0 is V0 and the output voltage (angular voltage) of the central Hall element 41 is greater than V0 with respect to a certain magnetic field equal to each Hall element 41, the two Hall elements on both sides The output voltage (angle voltage) 41 is a value smaller than V0.
[0020]
The hall element 41 at the left end in FIG. 2 is arranged at a position for outputting an angle signal for switching control of the U-phase voltage. The hall element 41 at the right end in FIG. 2 is arranged at a position for outputting an angle signal for switching control of the V-phase voltage. The center Hall element 41 in FIG. 2 is arranged at a position where a -W phase voltage is generated. For this reason, the center Hall element 41 is arranged upside down with respect to the other Hall elements so that the W-phase voltage can be output. For this reason, the offset magnetic field acting on the central Hall element 41 is opposite in sign to the offset magnetic fields acting on the other two Hall elements. The -W phase voltage referred to here is a voltage obtained by phase shifting the W phase voltage by an electrical angle π, and becomes equal to the W phase voltage by inversion. Since the specific circuit configuration of the detection unit 42 of the rotation angle sensor 4 is already well known, further description thereof is omitted.
[0021]
For comparison with the rotation angle sensor 4 of the Hall element 120 degree arrangement type shown in FIG. 2, the rotation angle sensor 4 of the Hall element 240 degree arrangement type is shown in FIG. In FIG. 3, reference numeral 40 denotes a disk-shaped rotating magnetic pole portion fixed to the rotating shaft, 410 denotes three Hall elements, and 42 denotes a detecting portion incorporating these Hall elements 410. α is an angle between adjacent Hall elements 41, 41, and is set to an electrical angle of 120 degrees, that is, 2π / 3 in a three-phase brushless DC motor. R is a radius from the axial center to the position of the Hall element 41. In the rotating magnetic pole part 40, permanent magnet parts equal to the number of rotor magnetic poles are alternately arranged in the circumferential direction.
[0022]
FIG. 4 shows an example of the waveform of the output voltage (angle voltage) of each Hall element 41 of the rotation angle sensor of the Hall element 240-degree arrangement type shown in FIG. 3, and these output voltages are set to threshold values at which the magnetic field becomes zero. The waveform of the pulse voltage (angle signal) obtained by binarization is shown in FIGS. However, in FIG. 4, it is assumed that an external leakage magnetic field or the like does not act on each Hall element 41 and the offset voltage is not superimposed on the output voltage of each Hall element 41.
[0023]
FIG. 8 shows an example of the waveform of the output voltage (angle voltage) of each Hall element 41 of the rotation angle sensor of the Hall element 240 degree arrangement method shown in FIG. 3, and these output voltages are set at a threshold value at which the magnetic field becomes zero. The waveforms of the pulse voltage (angle signal) obtained by binarization are shown in FIGS. However, in FIG. 8, it is assumed that an external leakage magnetic field or the like acts on each Hall element 41 and an offset voltage is superimposed on the output voltage of each Hall element 41. As apparent from FIGS. 9 to 11, when a DC offset voltage acts on these Hall elements 41, the pulse voltage (angle signal) deviates from the original duty ratio of 50%, and at an angular position deviated from the original rotor angle. A serious angle detection error that the level changes occurs. When the offset voltage superimposed on each Hall element 41 is equal, it is obvious that the offset voltage can be canceled from the output voltage difference (interphase angle voltage) by detecting the output voltage difference between the two Hall elements 41. This output voltage difference (interphase angle voltage) is merely shifted from the original output voltage of the Hall element 41 by a predetermined phase angle. Therefore, if the rotating magnetic pole portion 41 is set in consideration of this predetermined phase angle, switching is performed. As described above, the angle signal for control can be obtained without any problem. 4 and 8, Su is, for example, the output voltage of the leftmost Hall element 41, Sv is, for example, the output voltage of the central Hall element 41, and Sw is, for example, the output voltage of the rightmost Hall element 41.
[0024]
FIG. 12 shows an example of the waveform of the output voltage (angle voltage) of each Hall element 41 of the rotation angle sensor of the Hall element 120-degree arrangement type shown in FIG. 2, and these output voltages are set to threshold values at which the magnetic field becomes zero. The waveforms of the pulse voltage (angle signal) obtained by binarization are shown in FIGS. However, in FIG. 12, it is assumed that an external leakage magnetic field or the like acts on each Hall element 41 and the offset voltage is not superimposed on the output voltage of each Hall element 41. In FIG. 12, Su is the output voltage of the leftmost Hall element 41, Sv is the output voltage of the rightmost Hall element 41, and Sw is the voltage obtained by inverting the output voltage of the central Hall element 41.
[0025]
FIG. 16 shows an example of the waveform of the output voltage (angle voltage) of each Hall element 41 of the rotation angle sensor of the Hall element 120-degree arrangement type shown in FIG. 2, and these output voltages are set to threshold values at which the magnetic field becomes zero. The waveform of the pulse voltage (angle signal) obtained by binarization is shown in FIGS. However, in FIG. 16, it is assumed that an external leakage magnetic field or the like acts on each Hall element 41 and an offset voltage is superimposed on the output voltage of each Hall element 41. As apparent from FIGS. 17 to 19, when a DC offset voltage acts on these Hall elements 41, the pulse voltage (angle signal) deviates from the original duty ratio of 50%, at an angular position deviated from the original rotor angle. A serious angle detection error that the level changes occurs.
[0026]
In this Hall element 120-degree arrangement method, in order to obtain the W-phase voltage Sw by inverting the output voltage of the center Hall element 41, the offset voltage superimposed on the W-phase voltage Sw is the output voltage of the other Hall element 41. It is superimposed in the opposite direction to Su and Sv. Therefore, the offset voltage cannot be canceled by a conventionally known method of detecting a phase difference.
[0027]
Next, the offset voltage canceling method of this embodiment will be described below.
[0028]
Hereinafter, it is assumed that the amplitude of the output voltages Su, Sv, Sw of each Hall element 41 is 0 V to Vcc, and the output voltage in the magnetic field 0 is 0.5 Vcc at the offset voltage 0.
[0029]
If the AC signal voltage component in the output voltage Su when the offset voltage is 0 is Sac, the AC signal voltage component in the output voltage Sv is Svac, and the AC signal voltage component in the output voltage Sw is Swac, When the voltage is 0, the output voltage Su is Suac + 0.5 Vcc, the output voltage Sv is Svac + 0.5 Vcc, the output voltage Sw is Swac + 0.5 Vcc, and Suac + Svac + Swac is 0.
[0030]
If a DC output voltage due to an external magnetic field or the like, that is, an offset voltage referred to in this specification is Voffset and the magnitudes are equal for each sensor, the output voltage Su is Suac + 0.5Vcc + Voffset, the output voltage Sv is Svac + 0.5Vcc + Voffset, and the output voltage Sw is Swac + 0.5Vcc-Voffset.
[0031]
Therefore, when the output voltage sum ΣV = Su + Sv + Sw is calculated,
ΣV = Swac + 0.5Vcc + Voffset + Svac + 0.5Vcc + Voffset + Swac + 0.5Vcc−Voffset = 1.5Vcc + Voffset
It becomes. Therefore, the offset voltage Voffset is
Voffset = ΣV−1.5Vcc = Su + Sv + Sw−1.5Vcc
It becomes. Since Vcc is known, the offset voltage Voffset can be calculated by this calculation. Next, the AC signal components Suac, Svac, Swac can be calculated by substituting the offset voltage Voffset, the known Vcc, and the output voltages Su, Sv, Sw of each Hall element 41 into the following equations.
[0032]
Su = Suac + 0.5Vcc + Voffset,
Sv = Svac + 0.5 Vcc + Voffset,
Sw = Swac + 0.5Vcc-Voffset
If the AC angular voltages Suac, Svac, Swac of each sensor are arranged,
Suac = Su-0.5Vcc-Voffset,
Svac = Sv−0.5 Vcc−Voffset,
Swac = Sw−0.5Vcc + Voffset
Substituting the values of Su, Sv, Sw, Vcc, and Voffset for the calculation.
[0033]
These AC signal components Suac, Svac, and Swac are binarized or multi-leveled as in the prior art to form angle signals. This calculation can be performed by an analog hardware circuit, digital hardware, or microcomputer software. Thereby, the offset voltage Voffset can be canceled while adopting the rotation angle sensor 4 of the Hall element 120-degree arrangement method by a simple calculation, and thus a small and highly accurate rotation angle sensor 4 can be realized.
[0034]
(Example 2)
In the first embodiment, the AC signal components Suac, Svac, Swac are extracted from the angular voltage of each sensor. Instead, the interphase angular voltage is calculated, and the interphase angular voltage is binarized or multi-level as in the prior art. It is good also as an angle signal.
[0035]
Further explanation will be made as follows as described above.
[0036]
Su = Suac + 0.5Vcc + Voffset,
Sv = Svac + 0.5 Vcc + Voffset,
Sw = Swac + 0.5Vcc-Voffset
Therefore, when calculating the phase angle voltage S1x = Su-Sv, S2x = Sv-Sw, S3x = Sw-Su,
S1x = Su-Sv = Suac-Svac
S2x = Sv-Sw = Svac-Swac + 2Voffset
S3x = Sw-Su = Swac-Suc-2Voffset
It becomes.
[0037]
Therefore, when calculating the phase angle voltage S1 = S1x, S2 = S2x-2Voffset, S3 = S3x + 2Voffset,
S1 = Suac-Svac
S2 = Svac-Swac
S3 = Swac-Suac
It becomes. That is, the phase angle voltages S1, S2, and S3 calculated in this way are out of phase by an electrical angle π / 6 with respect to the original output voltages (AC angle voltages) Suac, Svac, and Swac of each Hall element 41. It can be seen that the angle voltage is (advanced).
[0038]
That is, if the switching control of the motor is performed using the phase angle voltages S1, S2, and S3, the switching control of the motor is performed in the same circuit using the output voltages (angular voltages) Su, Sv, and Sw of the Hall elements 41. Compared to the above, the offset voltage Voffset can be canceled, and the motor can be operated in a phase-advanced state while employing a small rotation angle sensor 4. It is obvious that the calculation of this embodiment can be performed by an analog hardware circuit, digital hardware, or microcomputer software as in the first embodiment.
[0039]
Example 3
The motor switching control using the AC angular voltages Suac, Svac, Swac obtained in the first embodiment and the motor switching control using the interphase angular voltages S1, S2, S3 obtained in the second embodiment can be appropriately switched. it can. In this embodiment, switching is performed according to the motor rotation speed. As a result, motor characteristics suitable for each rotation speed range can be realized.
[0040]
For example, when the speed is less than a predetermined threshold speed, the motor switching control of the first embodiment is performed, and when the rotation speed exceeds the threshold value, the motor switching control of the second embodiment is switched. FIG. 20 shows changes in motor characteristics due to this advance angle switching.
[0041]
Since the rotational speed can be obtained from the frequency of the angle signal obtained by binarizing the angular voltage of each phase or the inter-phase angular voltage output from the rotational angle sensor 4, if it is less than the threshold rotational speed Nc in FIG. Switching control is performed at an advance angle of 0 degrees of the first embodiment shown by A-C, and thereby a large low speed torque can be obtained. Also, if the rotational speed is equal to or higher than the threshold rotational speed Nc, switching control is performed at an advance angle of 30 degrees of the second embodiment indicated by CB ′ in FIG. 20, thereby obtaining a large high speed torque.
[0042]
The advance angle switching method of this embodiment simply switches the angle voltage of each phase obtained from the output voltages Su, Sv, Sw of each Hall element 41 and the angle voltage between each phase, and therefore it can be accurately performed with a simple circuit configuration. In addition to the excellent advantage that an advance angle of 30 degrees can be obtained, the offset voltage Voffset can be canceled in both the advance angle 0 degree control and the advance angle 30 degree control, and the rotation angle sensor 4 can be downsized. . However, this advance angle switching method may be adopted in the Hall element 240 degree arrangement method, or may be adopted in the Hall element 120 degree arrangement method that does not perform the offset voltage Voffset cancellation calculation of the first and second embodiments. .
[0043]
FIG. 21 shows a motor control circuit for controlling the three-phase brushless DC motor 1 shown in FIG. Reference numeral 10 is an inverter circuit that converts a DC voltage into a three-phase AC voltage, 11 is a control circuit that performs switching control of the inverter circuit 10, and 12 and 12 are current sensors that detect U and V phase currents. The control circuit 11 controls the inverter 10 in order to enable operation at a required torque or rotational speed based on the three-phase angle signal from the detection unit 42 of the rotation angle sensor 4 and the detection currents of the two current sensors 12. Each switching element is intermittently controlled. The detection unit 42 of the rotation angle sensor 4 outputs the above-described angular voltage or interphase angular voltage to the control circuit 11. In particular, in this embodiment, the detection unit 42 outputs an angle signal obtained by binarizing the angular voltage of the first embodiment when the rotational speed is less than the threshold rotational speed Nc. An angle signal obtained by binarizing the interphase angle voltage of 2 is output.
[0044]
An example of the circuit configuration of the detector 42 is shown in FIG.
[0045]
Reference numerals 100 to 102 denote operational amplifier multiplying circuits, which multiply the displayed values. Reference numerals 103 to 109 denote subtraction circuits or addition / subtraction circuits, which perform subtraction or addition / subtraction. Reference numeral 110 denotes an analog switching circuit, and three analog switching circuits are provided. Reference numeral 112 denotes a Schmitt trigger circuit, and three are provided. Ss is a switching signal obtained by binarizing an analog voltage proportional to the motor speed at a predetermined threshold value, and switches the analog switching circuit 110. So1, So2, and So3 are angle signals output to the control circuit 11 for switching control of each phase.
[0046]
FIG. 23 shows a flowchart when the analog hardware operation shown in FIG. 22 is changed to a software operation.
[0047]
(Example 4)
A configuration of the detection unit 42 of the rotation angle sensor 4 suitable for the first to third embodiments will be described with reference to FIG. In this embodiment, the detection unit 42 is formed by one monolithic integrated circuit, 200 is a silicon chip, 201 is a U-phase Hall effect resistance film, 202 is a V-phase Hall effect resistance film, and 203 is W It is a phase Hall effect resistance film. The Hall effect resistance films 201 to 203 are simultaneously formed by patterning on the silicon chip 200 by photolithography. However, the Hall effect resistance films 201 to 203 are configured to be located on the circumference of the radius R by an angle α / 2 (= electrical angle π / 3) when the silicon chip 200 is viewed from the upper surface thereof. ing. The Hall effect resistance film 201 substantially corresponds to the magnetoelectric conversion part of the U-phase Hall element 41 described above, and the Hall effect resistance film 202 substantially corresponds to the magnetoelectric conversion part of the W-phase Hall element 41 described above. The Hall effect resistance film 203 substantially corresponds to the magnetoelectric conversion portion of the V-phase Hall element 41 described above. In order to reverse the magnetoelectric conversion characteristics of the Hall effect resistance film 202, the direction of the current flowing through the Hall effect resistance film 202 is reversed with respect to the direction of the current flowing through the other Hall effect resistance films 201 and 203. The output voltage of each of the Hall effect resistance films 201 to 203 is subjected to processing such as amplification by the silicon chip 200, and converted into an angle signal by the noise canceling / binarizing circuit shown in FIG. .
[0048]
In this case, since the detection unit 42 can be configured by one monolithic IC, the Hall effect resistance films 201 to 203 can be formed at the same time, so that the variation in distance between them can be made almost zero. be able to. In addition, since the detection part 42 of this embodiment employs the Hall element 120-degree arrangement method, as described above, an electrical angle π / 3 is required as the interval between the Hall effect resistance films 201 to 203. The interval may be half as compared with the case where the Hall element 240 degree arrangement method is adopted, and it is not necessary to increase the size of the silicon chip, so that the manufacturing cost can be greatly reduced.
[0049]
(Example 5)
Another configuration of the detection unit 42 of the rotation angle sensor 4 suitable for the first to third embodiments will be described with reference to FIG. In this embodiment, the detection unit 42 is formed by one hybrid integrated circuit, 300 is a ceramic substrate, 301 is a U-phase Hall effect resistance film, 302 is a -W-phase Hall effect resistance film, and 303 is A V-phase Hall effect resistance film 304 is an IC chip equivalent to the silicon chip 200 shown in FIG. Each of the Hall effect resistance films 301 to 303 is patterned and formed on the ceramic substrate 300 in the same process, and is connected to a predetermined conductor pattern on the IC chip 304 by a conductor pattern (not shown) or wire bonding wiring. The Hall effect resistance film 301 substantially corresponds to the magnetoelectric conversion portion of the U-phase Hall element 41 described above, and the Hall effect resistance film 302 substantially corresponds to the magnetoelectric conversion portion of the −W phase Hall element 41 described above. The Hall effect resistance film 303 substantially corresponds to the magnetoelectric conversion portion of the V-phase Hall element 41 described above. In order to reverse the magnetoelectric conversion characteristics of the Hall effect resistance film 302, the direction of the current flowing through the Hall effect resistance film 302 is reversed with respect to the direction of the current flowing through the other Hall effect resistance films 301 and 303. The output voltage of each of the Hall effect resistance films 301 to 303 is subjected to processing such as amplification by the IC chip 304, and then converted into an angle signal by the noise canceling / binarizing circuit shown in FIG. Is done.
[0050]
In this way, since the detection unit 42 can be configured by one hybrid IC, the Hall effect resistance films 301 to 303 can be formed at the same time, so that the distance variation between them is almost zero. be able to. In addition, since the detection part 42 of this embodiment employs the Hall element 120-degree arrangement method, as described above, an electrical angle π / 3 is required as the interval between the Hall effect resistance films 301 to 303. The interval may be half as compared with the case where the Hall element 240 degree arrangement method is adopted, and it is not necessary to increase the size of the silicon chip, so that the manufacturing cost can be greatly reduced.
[0051]
(Modification)
In the above embodiment, a Hall element is used as the magnetoelectric conversion element, but an element using a magneto-electric effect other than the Hall effect can be used.
[0052]
(Modification)
In the above embodiment, noise cancellation and advance angle switching are performed by the detection unit 42 of the rotation angle sensor 4, but it is needless to say that it may be performed in the control circuit 11.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view in an axial direction showing a multiphase motor according to Embodiment 1.
2 is a schematic perspective view of a rotation angle sensor showing a Hall element 120-degree arrangement method according to Embodiment 1. FIG.
FIG. 3 is a schematic perspective view of a rotation angle sensor showing a Hall element 240 degree arrangement method of a reference example.
FIG. 4 is a waveform diagram of an output voltage (angle voltage) of a rotation angle sensor of a Hall element 240 degree arrangement method.
5 is a waveform diagram of an angle signal obtained by binarizing the U-phase output voltage of FIG. 4;
6 is a waveform diagram of an angle signal obtained by binarizing the V-phase output voltage of FIG.
7 is a waveform diagram of an angle signal obtained by binarizing the W-phase output voltage of FIG.
FIG. 8 is a waveform diagram of an output voltage (angle voltage) of a rotation angle sensor of the Hall element 240 degree arrangement method.
9 is a waveform diagram of an angle signal obtained by binarizing the U-phase output voltage of FIG.
10 is a waveform diagram of an angle signal obtained by binarizing the V-phase output voltage of FIG.
11 is a waveform diagram of an angle signal obtained by binarizing the W-phase output voltage of FIG.
FIG. 12 is a waveform diagram of an output voltage (angle voltage) of a rotation angle sensor of a Hall element 120-degree arrangement method.
13 is a waveform diagram of an angle signal obtained by binarizing the U-phase output voltage of FIG.
14 is a waveform diagram of an angle signal obtained by binarizing the V-phase output voltage of FIG.
15 is a waveform diagram of an angle signal obtained by binarizing the W-phase output voltage of FIG.
FIG. 16 is a waveform diagram of an output voltage (angle voltage) of a rotation angle sensor of a Hall element 120-degree arrangement method.
17 is a waveform diagram of an angle signal obtained by binarizing the U-phase output voltage of FIG.
18 is a waveform diagram of an angle signal obtained by binarizing the V-phase output voltage of FIG.
19 is a waveform diagram of an angle signal obtained by binarizing the W-phase output voltage of FIG.
FIG. 20 is a characteristic diagram showing the relationship between motor rotation speed and torque.
FIG. 21 is a control circuit diagram of the motor shown in FIG. 1;
FIG. 22 is a circuit diagram for performing offset voltage cancellation and advance angle switching.
FIG. 23 is a flowchart for performing offset voltage cancellation and advance angle switching.
FIG. 24 is a schematic side view showing a configuration of a detection unit of the rotation angle sensor.
FIG. 25 is a schematic plan view illustrating a configuration of a detection unit of the rotation angle sensor.
[Explanation of symbols]
1 Three-phase brushless DC motor (multi-phase motor)
2 Landel rotor
3 Stator
4 Rotation angle sensor
5 Housing
6 Brush device
7 Slip ring
8 Rotating shaft
40 Rotating magnetic pole part of rotation angle sensor
41 Hall element (magnetoelectric conversion element, angle detector)
42 detection unit (angle detection unit, angle signal processing unit)

Claims (7)

A rotating magnetic pole portion fixed to the rotating shaft of a multi-phase motor having a stator having three or more phase coils and a rotor rotating facing the stator at predetermined intervals in the circumferential direction and alternately with polarity;
An angular voltage having a positive correlation with the magnitude of the magnetic field of the rotating magnetic pole portion is disposed on the housing side of the multi-phase motor while facing the rotating magnetic pole portion at a predetermined distance and spaced apart from each other by a predetermined angle in the circumferential direction. An angle detector including first, second and third magnetoelectric transducers to output;
An angle signal processing unit that extracts an angle signal including information related to the angle of the rotation axis based on the angle voltage and the number of the magnetoelectric transducers;
A stator current control unit that performs switching control of a current supplied to each phase coil based on each angle signal;
With
The second magnetoelectric transducer is
In the multiphase motor control device arranged so that its output is in the opposite direction to the output of the first and third magnetoelectric transducers,
The angle signal processor is
The offset voltage has been canceled by substituting the three angular voltages into a predetermined formula with the angular voltages output by the first, second, and third magnetoelectric transducers as variables. A multi-phase motor control device that extracts three angle signals. The multiphase motor control device according to claim 1,
The angle signal processing unit outputs three angle signals having a predetermined phase angle with respect to three phase voltages applied to each phase terminal of a three-phase brushless DC motor as the multiphase motor,
The first magnetoelectric transducer outputs the angular voltage corresponding to the phase angle of the U-phase voltage of the three phase voltages,
The second magnetoelectric conversion element corresponds to the phase angle of the -W phase voltage of the three phase voltages with an electrical angle of π / 3 away from the first magnetoelectric conversion element to one side in the circumferential direction. Output angular voltage,
The third magnetoelectric conversion element is at an angle corresponding to a phase angle of a V phase voltage of the three phase voltages at an electrical angle of 2π / 3 away from the first magnetoelectric conversion element in a predetermined direction in the circumferential direction. A multi-phase motor control device that outputs a voltage. In the multiphase motor control device according to claim 1 or 2,
The angle signal processor is
The offset voltage is extracted by substituting the three angular voltages into a predetermined formula with the angular voltage output from the first, second, and third magnetoelectric transducers as a variable, and calculating the offset voltage, The multi-phase motor control device, wherein the three angle signals are extracted by subtracting the offset voltage from the angle voltage. In the multiphase motor control device according to claim 1 or 2,
The angle signal processor is
The offset voltage is canceled by inverting the angular voltage output from the second magnetoelectric transducer to obtain an angular voltage of the W phase, and calculating an interphase voltage of the angular voltages of the U, V, and W phases. The multi-phase motor control device, wherein the three angle signals are extracted. In the multiphase motor control device according to claim 3 and 4,
The angle signal processor is
A first control mode for switching and controlling a current to be supplied to each of the phase coils using the angle signal according to claim 3, and a current to the each phase coil using the angle signal according to claim 4. A multi-phase motor control device that switches between a second control mode for performing switching control of current according to the number of rotations of the motor detected based on the angle signal. A rotating magnetic pole portion fixed to the rotating shaft of a multi-phase motor having a stator having three or more phase coils and a rotor rotating facing the stator at predetermined intervals in the circumferential direction and alternately with polarity;
An angular voltage having a positive correlation with the magnitude of the magnetic field of the rotating magnetic pole portion is disposed on the housing side of the multi-phase motor while facing the rotating magnetic pole portion at a predetermined distance and spaced apart from each other by a predetermined angle in the circumferential direction. An angle detector including first, second and third magnetoelectric transducers to output;
An angle signal processing unit that extracts an angle signal including information related to the angle of the rotation axis based on the angle voltage and the number of the magnetoelectric transducers;
A stator current control unit that performs switching control of a current supplied to each phase coil based on each angle signal;
With
The second magnetoelectric transducer is
In the multiphase motor control device arranged so that its output is in the opposite direction to the output of the first and third magnetoelectric transducers,
The first, second, and third magnetoelectric transducers are formed on the same substrate by the same process and are formed integrally with the angle signal processing unit. A rotating magnetic pole portion fixed to the rotating shaft of a multi-phase motor having a stator having three or more phase coils and a rotor rotating facing the stator at predetermined intervals in the circumferential direction and alternately with polarity;
An angular voltage having a positive correlation with the magnitude of the magnetic field of the rotating magnetic pole portion is disposed on the housing side of the multi-phase motor while facing the rotating magnetic pole portion at a predetermined distance and spaced apart from each other by a predetermined angle in the circumferential direction. An angle detector including first, second and third magnetoelectric transducers to output;
An angle signal processing unit that extracts an angle signal including information related to the angle of the rotation axis based on the angle voltage and the number of the magnetoelectric transducers;
A stator current control unit that performs switching control of a current supplied to each phase coil based on each angle signal;
In a multiphase motor control device comprising:
The angle signal processor is
Extracting an angle signal corresponding to the angle voltage output from the first, second and third magnetoelectric transducers at less than a predetermined number of revolutions,
Extracting an angle signal corresponding to an interphase angular voltage, which is a difference between two angular voltages among the angular voltages of the first, second and third magnetoelectric transducers at the predetermined rotational speed or more; Multiphase motor control device.

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