Three-phase signal generation device; method for generating three-phase signals

Abstract

One aspect of a three-phase signal generation device of the present invention is such that: a first complex vector, a second complex vector, and a third complex vector are calculated on the basis of instantaneous values of a first signal, a second signal, and a third signal; in the complex number plane, the center of gravity of a triangle having, as one side, a straight line connecting the vertex of the first complex vector and the vertex of the third complex vector, is calculated as a first center of gravity; the center of gravity of a triangle having, as one side, a straight line connecting the vertex of the first complex vector and the vertex of the second complex vector, is calculated as a second center of gravity; the center of gravity of a triangle having, as one side, a straight line connecting the vertex of the second complex vector and the vertex of the third complex vector, is calculated as a third center of gravity; the center of gravity of a triangle having the first center of gravity, the second center of gravity, and the third center of gravity as vertices, is calculated; and the first complex vector, the second complex vector, and the third complex vector are corrected by converting this center of gravity to the origin point of the complex number plane.

Description

Technical Field

[0001] The present invention relates to a three-phase signal generation device and a three-phase signal generation method. This application claims priority based on Japanese Patent Application No. 2021-161924 filed in Japan on September 30, 2021, the content of which is incorporated herein by reference.

Background Art

[0002] Conventionally, as a motor capable of accurately controlling the rotational position, a configuration including an absolute angle position sensor such as an optical encoder or a resolver is known. However, the absolute angle position sensor is large-sized and costly. Therefore, Patent Document 1 discloses a position estimation method for estimating the mechanical angle of a rotation axis using three inexpensive and small-sized magnetic sensors without using an absolute angle position sensor.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the position estimation method described in Patent Document 1, the mechanical angle of the rotation axis can be estimated with high accuracy using three inexpensive and small-sized magnetic sensors, but higher accuracy may be required in the market.

Means for Solving the Problems

[0005] One embodiment of the three-phase signal generating device of the present invention comprises: a first magnetic sensor that faces a rotating magnet and outputs a first signal indicating magnetic field strength; a second magnetic sensor that faces the magnet and outputs a second signal having a phase delay of 120° in electrical angle with respect to the first signal; a third magnetic sensor that faces the magnet and outputs a third signal having a phase delay of 120° in electrical angle with respect to the second signal; and a signal processing unit that processes the first signal, the second signal, and the third signal. The signal processing unit performs the following: a first process of obtaining the instantaneous values ​​of the first signal, the second signal, and the third signal by digitally converting the first signal, the second signal, and the third signal; a second process of calculating a first complex vector, which is the complex vector of the first signal; a second complex vector, which is the complex vector of the second signal; and a third complex vector, which is the complex vector of the third signal, based on the instantaneous values ​​of the first signal, the second signal, and the third signal; and calculating the centroid of a triangle having a line connecting the vertex of the first complex vector and the vertex of the third complex vector as the first centroid in the complex plane. The following processes are performed: a third process; a fourth process in which the centroid of a triangle having a straight line connecting the vertex of the first complex vector and the vertex of the second complex vector as one side in the complex number plane is calculated as the second centroid; a fifth process in which the centroid of a triangle having a straight line connecting the vertex of the second complex vector and the vertex of the third complex vector as one side in the complex number plane is calculated as the third centroid; a sixth process in which the centroid of a triangle having the first centroid, the second centroid, and the third centroid as vertices is calculated; and a seventh process in which the first complex vector, the second complex vector, and the third complex vector are corrected by converting the centroid to the origin of the complex number plane.

[0006] One aspect of the three-phase signal generation method of the present invention is a three-phase signal generation method using: a first magnetic sensor that faces a rotating magnet and outputs a first signal indicating magnetic field strength; a second magnetic sensor that faces the magnet and outputs a second signal having a phase delay of 120° in electrical angle with respect to the first signal; and a third magnetic sensor that faces the magnet and outputs a third signal having a phase delay of 120° in electrical angle with respect to the second signal, wherein the method involves: a first step of obtaining the instantaneous values ​​of the first signal, the second signal, and the third signal by digitally converting the first signal, the second signal, and the third signal; and based on the instantaneous values ​​of the first signal, the second signal, and the third signal, a first complex vector which is the complex vector of the first signal, a second complex vector which is the complex vector of the second signal, and a third complex vector which is the complex vector of the third signal. The method comprises: a second step of calculating the centroid; a third step of calculating the centroid of a triangle having a straight line connecting the vertex of the first complex vector and the vertex of the third complex vector as one side in the complex plane, as the first centroid; a fourth step of calculating the centroid of a triangle having a straight line connecting the vertex of the first complex vector and the vertex of the second complex vector as one side in the complex plane, as the second centroid; a fifth step of calculating the centroid of a triangle having a straight line connecting the vertex of the second complex vector and the vertex of the third complex vector as one side in the complex plane, as the third centroid; a sixth step of calculating the centroid of a triangle having the first centroid, the second centroid, and the third centroid as vertices; and a seventh step of correcting the first complex vector, the second complex vector, and the third complex vector by converting the centroid to the origin of the complex plane. [Effects of the Invention]

[0007] According to the above aspects of the present invention, an angle detection method and a three-phase signal generation device are provided that can improve the estimation accuracy (detection accuracy) of the mechanical angle of a rotating shaft. [Brief explanation of the drawing]

[0008] [Figure 1]Figure 1 is a schematic block diagram showing the configuration of a three-phase signal generator 1 in one embodiment of the present invention. [Figure 2] Figure 2 shows examples of waveforms for the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. [Figure 3] Figure 3 is an enlarged view of the U-phase sensor signal Hu, V-phase sensor signal Hv, and W-phase sensor signal Hw included in one pole-pair region shown in Figure 2. [Figure 4] Figure 4 shows an example of the waveforms of the sensor signals Hu, Hv, and Hw, which include the common-mode signal, which is a noise component. [Figure 5] Figure 5 shows an example of the waveforms of the sensor signals Hiu0, Hiv0, and Hiw0 obtained after the first correction process. [Figure 6] Figure 6 shows an example of the waveforms of the sensor signals Hiu1, Hiv1, and Hiw1 obtained after the execution of the second correction process. [Figure 7] Figure 7 shows an example of the waveforms of the sensor signals Hiu2, Hiv2, and Hiw2 obtained after the execution of the third correction process. [Figure 8] Figure 8 is a flowchart showing the learning process performed by the processing unit 21 of the three-phase signal generator 1 in this embodiment. [Figure 9] Figure 9 is a complex number plane diagram used to explain the processes of steps S1 and S2 included in the three-phase signal generation process. [Figure 10] Figure 10 is a complex number plane diagram used to illustrate the processes from step S3 to step S6 included in the three-phase signal generation process. [Figure 11] Figure 11 is a complex number plane diagram used to illustrate the process of step S7 included in the three-phase signal generation process. [Figure 12] Figure 12 is the first figure showing the simulation results of the three-phase signal obtained by the three-phase signal generation process. [Figure 13] Figure 13 is the second figure showing the simulation results of the three-phase signal obtained by the three-phase signal generation process. [Modes for carrying out the invention]

[0009] Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings. Figure 1 is a schematic block diagram showing the configuration of the three-phase signal generation device 1 in one embodiment of the present invention. As shown in Figure 1, the three-phase signal generation device 1 is a device that detects the mechanical angle (rotation angle) of the rotor shaft 110, which is the rotation axis of the motor 100. In this embodiment, the motor 100 is, for example, an inner rotor type three-phase brushless DC motor. The motor 100 has a rotor shaft 110 and a sensor magnet 120.

[0010] The sensor magnet 120 is a disc-shaped magnet attached to the rotor shaft 110. The sensor magnet 120 rotates in synchronization with the rotor shaft 110. The sensor magnet 120 has P (P is an integer greater than or equal to 1) magnetic pole pairs. In this embodiment, as an example, the sensor magnet 120 has four magnetic pole pairs. A magnetic pole pair refers to a pair of north poles and south poles. That is, in this embodiment, the sensor magnet 120 has four pairs of north poles and south poles, for a total of eight magnetic poles.

[0011] The three-phase signal generator 1 comprises a sensor group 10 and a signal processing unit 20. Although not shown in Figure 1, a circuit board is mounted on the motor 100, and the sensor group 10 and the signal processing unit 20 are arranged on the circuit board. The sensor magnet 120 is positioned so as not to interfere with the circuit board. The sensor magnet 120 may be located inside the housing of the motor 100, or it may be located outside the housing.

[0012] The sensor group 10 includes a first magnetic sensor 11, a second magnetic sensor 12, and a third magnetic sensor 13. The first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are arranged on the circuit board in a state facing the sensor magnet 120. In the present embodiment, the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are arranged on the circuit board at intervals of 30° along the rotation direction of the sensor magnet 120. For example, the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are each an analog output type magnetic sensor including a magnetoresistive element such as a Hall element or a linear Hall IC. The first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 each output an analog signal indicating the magnetic field strength that changes according to the rotation position of the rotor shaft 110, that is, the rotation position of the sensor magnet 120.

[0013] One electrical angle cycle of the analog signals output from the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 corresponds to 1 / P of one mechanical angle cycle. In the present embodiment, since the number of pole pairs P of the sensor magnet 120 is "4", one electrical angle cycle of each analog signal corresponds to 1 / 4 of one mechanical angle cycle, that is, 90° in mechanical angle. The analog signal output from the second magnetic sensor 12 has a phase delay of 120° in electrical angle with respect to the analog signal output from the first magnetic sensor 11. The analog signal output from the third magnetic sensor 13 has a phase delay of 120° in electrical angle with respect to the analog signal output from the second magnetic sensor 12.

[0014] Hereinafter, the analog signal output from the first magnetic sensor 11 is referred to as a U-phase sensor signal Hu, the analog signal output from the second magnetic sensor 12 is referred to as a V-phase sensor signal Hv, and the analog signal output from the third magnetic sensor 13 is referred to as a W-phase sensor signal Hw.

[0015] The first magnetic sensor 11 faces the sensor magnet 120 which is a rotating magnet, and outputs a U-phase sensor signal Hu (first signal) indicating the magnetic field strength to the signal processing unit 20. The second magnetic sensor 12 faces the sensor magnet 120, and outputs a V-phase sensor signal Hv (second signal) having a phase delay of 120° in electrical angle with respect to the U-phase sensor signal Hu to the signal processing unit 20. The third magnetic sensor 13 faces the sensor magnet 120, and outputs a W-phase sensor signal Hw (third signal) having a phase delay of 120° in electrical angle with respect to the V-phase sensor signal Hv to the signal processing unit 20.

[0016] The signal processing unit 20 is a signal processing circuit that processes the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. The signal processing unit 20 estimates the mechanical angle of the rotor shaft 110 which is the rotation axis based on the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. The signal processing unit 20 includes a processing unit 21 and a storage unit 22.

[0017] The processing unit 21 is a microprocessor such as an MCU (Microcontroller Unit). The U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw are respectively input to the processing unit 21. The processing unit 21 is communicably connected to the storage unit 22 via a communication bus not shown. The processing unit 21 executes at least the following two processes according to a program stored in advance in the storage unit 22.

[0018] As an offline process, the processing unit 21 executes a learning process of obtaining learning data necessary for estimating the mechanical angle of the rotor shaft 110 based on the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. The offline process is a process executed before the three-phase signal generation device 1 is shipped from the manufacturing factory or before the three-phase signal generation device 1 is incorporated into the customer-side system and put into actual operation. It is a process executed before being put into actual operation.

[0019] Furthermore, the processing unit 21 performs an angle estimation process as an online process to estimate the mechanical angle of the rotor shaft 110 based on the U-phase sensor signal Hu, the V-phase sensor signal Hv, the W-phase sensor signal Hw, and the learning data obtained through the learning process. Online processing refers to the process that is executed when the three-phase signal generator 1 is incorporated into the customer's system and put into actual operation.

[0020] The memory unit 22 includes a non-volatile memory that stores programs necessary for the processing unit 21 to execute various processes, various setting data, and the above-mentioned learning data, and a volatile memory that is used as a temporary storage location for data when the processing unit 21 executes various processes. The non-volatile memory is, for example, EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash memory. The volatile memory is, for example, RAM (Random Access Memory).

[0021] Before describing the learning process and angle estimation process performed by the processing unit 21 of the three-phase signal generator 1 configured as described above, a brief explanation of the position estimation method disclosed in Japanese Patent No. 6233532 will be given to facilitate understanding of the present invention. In the following explanation, the position estimation method disclosed in Japanese Patent No. 6233532 may be referred to as the basic patent method. For details of the basic patent method, please refer to Japanese Patent No. 6233532. For the convenience of explanation, the basic patent method will be described below using the elements shown in Figure 1.

[0022] First, the learning process performed by the processing unit 21 in the basic patent method will be explained. The processing unit 21 acquires instantaneous values ​​(digital values) of the sensor signals Hu, Hv, and Hw output from each of the magnetic sensors 11, 12, and 13 while the sensor magnet 120 is rotating together with the rotor shaft 110. Specifically, the processing unit 21 has a built-in A / D converter, and the processing unit 21 acquires the instantaneous values ​​of the U-phase sensor signal Hu, V-phase sensor signal Hv, and W-phase sensor signal Hw by digitally converting each of the U-phase sensor signal Hu, V-phase sensor signal Hv, and W-phase sensor signal Hw at a predetermined sampling frequency using the A / D converter.

[0023] During the execution of the learning process, the rotor shaft 110 may be rotated by controlling the energization of the motor 100 via a motor control device (not shown). Alternatively, the rotor shaft 110 may be connected to a rotating machine (not shown), and the rotor shaft 110 may be rotated by that machine.

[0024] Figure 2 shows an example of the waveforms of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw. As shown in Figure 2, one electrical angle period of each of the sensor signals Hu, Hv, and Hw corresponds to 1 / 4 of one mechanical angle period, i.e., 90° in mechanical angle. In Figure 2, the period from time t1 to time t5 corresponds to one mechanical angle period (360° in mechanical angle). In Figure 2, the period from time t1 to time t2, the period from time t2 to time t3, the period from time t3 to time t4, and the period from time t4 to time t5 each correspond to 90° in mechanical angle. Also, the sensor signals Hu, Hv, and Hw have a phase difference of 120° in electrical angle from each other.

[0025] The processing unit 21 extracts, based on the digital values ​​of the sensor signals Hu, Hv, and Hw, the intersection points where two of the three sensor signals intersect each other, and the zero-crossing points where each of the three sensor signals intersects the reference signal level, over one mechanical angle period. The reference signal level is, for example, the ground level. When the reference signal level is the ground level, the digital value of the reference signal level is "0".

[0026] As shown in Figure 2, the processing unit 21 divides one mechanical angle period into four pole pair regions linked to pole pair numbers based on the zero-crossing point extraction results. In Figure 2, "No. C" indicates the pole pair number. As shown in Figure 1, pole pair numbers are pre-assigned to the four magnetic pole pairs of the sensor magnet 120. For example, the magnetic pole pair located in the range of 0° to 90° in mechanical angle is assigned pole pair number "0". The magnetic pole pair located in the range of 90° to 180° in mechanical angle is assigned pole pair number "1". The magnetic pole pair located in the range of 180° to 270° in mechanical angle is assigned pole pair number "2". The magnetic pole pair located in the range of 270° to 360° in mechanical angle is assigned pole pair number "3".

[0027] For example, when using the sensor signal Hu as a reference, the processing unit 21 recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t1) where the mechanical angle is 0° as the starting point of the pole pair region associated with pole pair number "0". The processing unit 21 also recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t2) where the mechanical angle is 90° as the ending point of the pole pair region associated with pole pair number "0". In other words, the processing unit 21 determines the interval between the zero-crossing point obtained at time t1 and the zero-crossing point obtained at time t2 as the pole pair region associated with pole pair number "0".

[0028] The processing unit 21 recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t2) where the mechanical angle is 90° as the starting point of the pole pair region associated with pole pair number "1". The processing unit 21 also recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t3) where the mechanical angle is 180° as the ending point of the pole pair region associated with pole pair number "1". In other words, the processing unit 21 determines the interval between the zero-crossing point obtained at time t2 and the zero-crossing point obtained at time t3 as the pole pair region associated with pole pair number "1".

[0029] The processing unit 21 recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t3) where the mechanical angle is 180° as the starting point of the pole pair region associated with pole pair number "2". The processing unit 21 also recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t4) where the mechanical angle is 270° as the ending point of the pole pair region associated with pole pair number "2". In other words, the processing unit 21 determines the interval between the zero-crossing point obtained at time t3 and the zero-crossing point obtained at time t4 as the pole pair region associated with pole pair number "2".

[0030] The processing unit 21 recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t4) where the mechanical angle is 270° as the starting point of the pole pair region associated with pole pair number "3". The processing unit 21 also recognizes the zero-crossing point of the sensor signal Hu obtained at the sampling timing (time t5) where the mechanical angle is 360° as the ending point of the pole pair region associated with pole pair number "3". In other words, the processing unit 21 determines the interval between the zero-crossing point obtained at time t4 and the zero-crossing point obtained at time t5 as the pole pair region associated with pole pair number "3".

[0031] As shown in Figure 2, the processing unit 21 divides each of the four pole-pair regions into 12 sections, each associated with a section number, based on the extraction results of intersection points and zero-crossing points. In Figure 2, "No. A" indicates the section number associated with each section. As shown in Figure 2, the 12 sections contained in each of the four pole-pair regions are associated with section numbers from "0" to "11".

[0032] Figure 3 is an enlarged view of the sensor signals Hu, Hv, and Hw contained within one pole-pair region shown in Figure 2. In Figure 3, the reference value of the amplitude (reference signal level) is "0". In Figure 3, a positive digital value of the amplitude represents, for example, the digital value of the magnetic field strength of the north pole. A negative digital value of the amplitude represents, for example, the digital value of the magnetic field strength of the south pole.

[0033] In Figure 3, points P1, P3, P5, P7, P9, P11, and P13 are zero-crossing points extracted from the digital values ​​of the sensor signals Hu, Hv, and Hw contained within one pole-pair region. Also in Figure 3, points P2, P4, P6, P8, P10, and P12 are intersection points extracted from the digital values ​​of the sensor signals Hu, Hv, and Hw contained within one pole-pair region. As shown in Figure 3, the processing unit 21 determines the interval between adjacent zero-crossing points and intersection points as a section.

[0034] The processing unit 21 determines that the section between zero-crossing point P1 and intersection point P2 is the section associated with section number "0". The processing unit 21 determines that the section between intersection point P2 and zero-crossing point P3 is the section associated with section number "1". The processing unit 21 determines that the section between zero-crossing point P3 and intersection point P4 is the section associated with section number "2". The processing unit 21 determines that the section between intersection point P4 and zero-crossing point P5 is the section associated with section number "3". The processing unit 21 determines that the section between zero-crossing point P5 and intersection point P6 is the section associated with section number "4". The processing unit 21 determines that the section between intersection point P6 and zero-crossing point P7 is the section associated with section number "5".

[0035] The processing unit 21 determines that the section between zero-crossing point P7 and intersection point P8 is associated with section number "6". The processing unit 21 determines that the section between intersection point P8 and zero-crossing point P9 is associated with section number "7". The processing unit 21 determines that the section between zero-crossing point P9 and intersection point P10 is associated with section number "8". The processing unit 21 determines that the section between intersection point P10 and zero-crossing point P11 is associated with section number "9". The processing unit 21 determines that the section between zero-crossing point P11 and intersection point P12 is associated with section number "10". The processing unit 21 determines that the section between intersection point P12 and zero-crossing point P13 is associated with section number "11".

[0036] In the following explanation, for example, a section assigned section number "0" will be referred to as "Section 0," and a section assigned section number "11" will be referred to as "Section 11."

[0037] As shown in Figure 2, a number that is continuous throughout the entire period of one machine angle cycle is associated with each section number as a segment number. In Figure 2, "No. B" indicates the segment number associated with each section number. A segment is a term that represents a straight line connecting adjacent intersection points and zero-crossing points. In other words, a straight line connecting the start and end points of each section is called a segment. In Figure 3, for example, the start point of section 0 is the zero-crossing point P1, and the end point of section 0 is the intersection point P2. Therefore, the segment corresponding to section 0 is the straight line connecting the zero-crossing point P1 and the intersection point P2. Similarly, in Figure 3, for example, the start point of section 1 is the intersection point P2, and the end point of section 1 is the zero-crossing point P3. Therefore, the segment corresponding to section 1 is the straight line connecting the intersection point P2 and the zero-crossing point P3.

[0038] As shown in Figure 2, in the pole-pair region associated with pole-pair number "0", segment numbers "0" to "11" are associated with section numbers "0" to "11". In the pole-pair region associated with pole-pair number "1", segment numbers "12" to "23" are associated with section numbers "0" to "11". In the pole-pair region associated with pole-pair number "2", segment numbers "24" to "35" are associated with section numbers "0" to "11". In the pole-pair region associated with pole-pair number "3", segment numbers "36" to "4 Up to "7" will be linked.

[0039] In the following explanation, for example, a segment assigned segment number "0" will be referred to as "Segment 1," and a segment assigned segment number "11" will be referred to as "Segment 11."

[0040] The processing unit 21 generates a linear function θ(Δx) representing each segment. Δx is the length (digital value) from the starting point of the segment to any point on the segment, and θ is the mechanical angle corresponding to any point on the segment. In Figure 3, for example, the starting point of the segment corresponding to section 0 is the zero-crossing point P1, and the ending point of the segment corresponding to section 0 is the intersection point P2. Similarly, in Figure 3, for example, the starting point of the segment corresponding to section 1 is the intersection point P2, and the ending point of the segment corresponding to section 1 is the zero-crossing point P3.

[0041] For example, the linear function θ(Δx) representing a segment is given by equation (1) below. In equation (1), "i" is the segment number and is an integer from 0 to 47. In the following explanation, the linear function θ(Δx) expressed by equation (1) below may be referred to as the machine angle estimation formula, and the machine angle θ calculated by equation (1) below may be referred to as the machine angle estimate. θ(Δx)=k[i]×Δx+θres[i] …(1)

[0042] In equation (1) above, k[i] is a coefficient called the normalization coefficient. In other words, k[i] is a coefficient that represents the slope of segment i. The normalization coefficient k[i] is expressed by equation (2) below. In equation (2) below, ΔXnorm[i] is the deviation of the digital value between the start point and the end point of segment i. In Figure 3, for example, ΔXnorm[i] of the segment corresponding to section 0 is the deviation of the digital value between the zero-crossing point P1 and the intersection point P2. Similarly, in Figure 3, for example, ΔXnorm[i] of the segment corresponding to section 1 is the deviation of the digital value between the intersection point P2 and the zero-crossing point P3. k[i]=θnorm[i] / ΔXnorm[i] …(2)

[0043] In equation (2) above, θnorm[i] is the deviation of the machine angle between the start and end points of segment i, and is expressed by equation (3) below. In equation (3) below, t[i] is the time between the start and end points of segment i, t[0] is the time between the start and end points of segment 0, and t

[47] is the time between the start and end points of segment 47. In Figure 3, for example, if the segment corresponding to section 0 is segment 0, then t[0] is the time between the zero-crossing point P1 and the intersection point P2. θnorm[i]={t[i] / (t[0]+…+t

[47] )}×360[degM] …(3)

[0044] In equation (1) above, θres[i] is a constant called the angle reset value of segment i (the intercept of the linear function θ(Δx)). When segment number "i" is "0", the angle reset value θres[i] is expressed by equation (4) below. When segment number "i" is any of "1" to "47", the angle reset value θres[i] is expressed by equation (5) below. Note that θnorm[i] may be obtained from the true mechanical angle (for example, the mechanical angle indicated by the output signal of an encoder attached to the rotor shaft 110) instead of from t[i] as described above. θres[i]=0[degM] …(4) θres[i]=Σ(θnorm[i-1]) …(5)

[0045] The processing unit 21 performs the learning process described above to obtain the correspondence between pole pair numbers, section numbers, and segment numbers, characteristic data for each section, and the mechanical angle estimation formula for each segment, and stores this obtained data in the storage unit 22 as learning data. The characteristic data for each section refers to the relative magnitudes and signs of the digital values ​​of the sensor signals Hu, Hv, and Hw included in each section. In addition, the normalization coefficient k[i] and angle reset value θres[i] that constitute the mechanical angle estimation formula for each segment are stored in the storage unit 22 as learning data.

[0046] Next, the angle estimation process performed by the processing unit 21 in the basic patent method will be described. The processing unit 21 acquires the sensor signals Hu, Hv, and Hw output from the magnetic sensors 11, 12, and 13. Specifically, the processing unit 21 acquires the digital values ​​of the U-phase sensor signal Hu, the V-phase sensor signal Hv, and the W-phase sensor signal Hw by digitally converting each of them at a predetermined sampling frequency using an A / D converter.

[0047] The processing unit 21 then identifies the current section number and pole pair number based on the digital values ​​of the sensor signals Hu, Hv, and Hw obtained at the current sampling timing. For example, in Figure 3, let's assume that the points PHu located on the waveform of the U-phase sensor signal Hu, PHv located on the waveform of the V-phase sensor signal Hv, and PHw located on the waveform of the W-phase sensor signal Hw are the digital values ​​of the respective sensor signals Hu, Hv, and Hw obtained at the current sampling timing. The processing unit 21 identifies the current section (section number) by comparing the characteristic data, such as the magnitude relationship and sign of the digital values ​​of points PHu, PHv, and PHw, with the characteristic data of each section included in the learning data stored in the storage unit 22. In the example in Figure 3, section 9 is identified as the current section. Note that the method for identifying the pole pair number is not described in this specification. For information on how to identify the pole pair number, please refer to Japanese Patent Publication No. 6233532. Let's assume that, for example, pole pair number "2" is identified as the pole pair number at the current sampling timing.

[0048] Then, the processing unit 21 identifies the current segment number based on the identified current section number and pole pair number. For example, the processing unit 21 identifies the current segment number using the formula "Segment number = 12 × pole pair number + section number". Assuming that section number "9" is identified as the current section number and pole pair number "2" is identified as the current pole pair number, the processing unit 21 identifies segment number "33" as the current segment number (see Figure 2).

[0049] The processing unit 21 reads the normalization coefficient k[i] and angle reset value θres[i] corresponding to the identified segment number "i" from the learning data stored in the memory unit 22, and calculates the estimated mechanical angle θ using the mechanical angle estimation formula expressed in equation (1) above. Here, the digital value of the sensor signal corresponding to the identified segment is used as Δx to be substituted into the mechanical angle estimation formula. For example, if segment number "33" is identified as the current segment number as described above, the processing unit 21 reads the normalization coefficient k

[33] and angle reset value θres

[33] from the memory unit 22, and calculates the estimated mechanical angle θ at the current sampling timing by substituting the digital value of point PHv (see Figure 3) as Δx into the mechanical angle estimation formula.

[0050] The above describes the basic procedure for estimating the mechanical angle in the basic patent method that forms the basis of the present invention. In the basic patent method, correction processing is performed on the sensor signals Hu, Hv, and Hw in order to improve the accuracy of the mechanical angle estimation (accuracy of the estimated mechanical angle θ). For example, as shown in Figure 2, the amplitude values ​​of each sensor signal Hu, Hv, and Hw do not necessarily coincide. Also, for example, as shown in Figure 4, each sensor signal Hu, Hv, and Hw may contain common-mode signals (such as DC signals and third-harmonic signals) which are noise components. Figure 4 shows an example of the waveforms of sensor signals Hu, Hv, and Hw that include common-mode signals which are noise components. In Figure 4, the vertical axis shows the digital value and the horizontal axis shows the electrical angle.

[0051] Therefore, when the processing unit 21 in the basic patent method acquires digital values ​​of the sensor signals Hu, Hv, and Hw during the execution of the learning process and the angle estimation process, it first performs a first correction process to remove common-mode signals from the sensor signals Hu, Hv, and Hw based on the following equations (6), (7), and (8). Hiu0 = Hu - (Hv + Hw) / 2 …(6) Hiv0 = Hv - (Hu + Hw) / 2 …(7) Hiw0 = Hw - (Hu + Hv) / 2 …(8)

[0052] In equation (6), Hiu0 is the digital value of the U-phase sensor signal obtained by performing a first correction process on the U-phase sensor signal Hu. In equation (7), Hiv0 is the digital value of the V-phase sensor signal obtained by performing a first correction process on the V-phase sensor signal Hv. In equation (8), Hiw0 is the digital value of the W-phase sensor signal obtained by performing a first correction process on the W-phase sensor signal Hw. Figure 5 shows an example of the waveforms of the sensor signals Hiu0, Hiv0, and Hiw0 obtained after performing the first correction process. In Figure 5, the vertical axis represents the digital value and the horizontal axis represents the electrical angle.

[0053] After performing the first correction process, the processing unit 21 in the basic patent method performs a second correction process to match the amplitude values ​​of the sensor signals Hiu0, Hiv0, and Hiw0 based on the following equations (9) to (14). Hiu1(ppn)=au_max(ppn)×Hiu0(ppn)+bu…(9) Hiu1(ppn)=au_min(ppn)×Hiu0(ppn)+bu…(10) Hiv1(ppn)=av_max(ppn)×Hiv0(ppn)+bv …(11) Hiv1(ppn)=av_min(ppn)×Hiv0(ppn)+bv …(12) Hiw1(ppn)=aw_max(ppn)×Hiw0(ppn)+bw …(13) Hiw1(ppn)=aw_min(ppn)×Hiw0(ppn)+bw …(14)

[0054] The processing unit 21 performs a second correction process on the positive digital value of the U-phase sensor signal Hiu0 using the information stored in the memory unit 22 according to equation (9) above. The processing unit 21 also performs a second correction process on the negative digital value of the U-phase sensor signal Hiu0 using the information stored in the memory unit 22 according to equation (10) above. The processing unit 21 performs a second correction process on the positive digital value of the V-phase sensor signal Hiv0 using the information stored in the memory unit 22 according to equation (11) above. The processing unit 21 also performs a second correction process on the negative digital value of the V-phase sensor signal Hiv0 using the information stored in the memory unit 22 according to equation (12) above. The processing unit 21 also performs a second correction process on the positive digital value of the W-phase sensor signal Hiw0 using the information stored in the memory unit 22 according to equation (13) above. Furthermore, the processing unit 21 performs a second correction process on the negative digital value of the W-phase sensor signal Hiw0 using the information stored in the storage unit 22 according to equation (14) above.

[0055] In equations (9) and (10), Hiu1 is the digital value of the U-phase sensor signal obtained by performing a second correction process on the U-phase sensor signal Hiu0. In equations (11) and (12), Hiv1 is the digital value of the V-phase sensor signal obtained by performing a second correction process on the V-phase sensor signal Hiv0. In equations (13) and (14), Hiw1 is the digital value of the W-phase sensor signal obtained by performing a second correction process on the W-phase sensor signal Hiw0. Figure 6 shows an example of the waveforms of the sensor signals Hiu1, Hiv1, and Hiw1 obtained after performing the second correction process. In Figure 6, the vertical axis represents the digital value and the horizontal axis represents the electrical angle.

[0056] Furthermore, in equations (9) to (14), pppn is the pole pair number from 0 to 3. In equations (9), (11), and (13), au_max(ppn), av_max(ppn), and aw_max(ppn) are the positive gain correction values ​​for the positive digital value for one period of electrical angle corresponding to each magnetic pole pair, which are pre-stored in the memory unit 22. In equations (10), (12), and (14), au_min(ppn), av_min(ppn), and aw_min(ppn) are the negative gain correction values ​​for the negative digital value for one period of electrical angle corresponding to each magnetic pole pair, which are pre-stored in the memory unit 22. In equations (9) to (14), bu, bv, and bw are the offset correction values ​​for each phase, which are pre-stored in the memory unit 22. Note that au_max(ppn), av_max(ppn), aw_max(ppn), au_min(ppn), av_min(ppn), and aw_min(ppn) are correction values ​​for each pole pair. Therefore, the number of positive-side gain correction values ​​is 12 (= 3 phases × 4 pole pairs). Similarly, the number of negative-side gain correction values ​​is also 12.

[0057] After performing the second correction process, the processing unit 21 in the basic patent method performs a third correction process on the sensor signals Hiu1, Hiv1, and Hiw1 to linearize a portion of the sensor signal (divided signal) corresponding to each segment. In Figure 3, for example, if the segment corresponding to section 0 is segment 0, the divided signal corresponding to segment 0 is the signal of the U-phase sensor signal Hu that connects the zero-crossing point P1 and the intersection point P2. Similarly, in Figure 3, for example, if the segment corresponding to section 1 is segment 1, the divided signal corresponding to segment 1 is the signal of the W-phase sensor signal Hw that connects the intersection point P2 and the zero-crossing point P3.

[0058] The processing unit 21 performs a third correction process on the sensor signals Hiu1, Hiv1, and Hiw1, changing the scale of each sensor signal by using values ​​pre-stored in the storage unit 22 as coefficients. By performing this third correction process, the roughly S-shaped form of the segmented signal corresponding to each segment can be straightened. Here, the values ​​stored in the storage unit 22 are pre-designed values. This third correction process is performed using the pre-designed values ​​and calculations are carried out using correction formulas such as quadratic functions, cubic functions, or trigonometric functions.

[0059] As an example, the processing unit 21 performs a third correction process on the sensor signals Hiu1, Hiv1, and Hiw1 based on equations (15) to (17) below. In equations (15) to (17) below, a and b are coefficients pre-stored in the storage unit 22. Hiu2 = b × tan(a × Hiu1) …(15) Hiv² = b × tan(a × Hiv¹) …(16) Hiw2 = b × tan(a × Hiw1) …(17)

[0060] In equation (15), Hiu2 is the digital value of the U-phase sensor signal obtained by performing a third correction process on the U-phase sensor signal Hiu1. In equation (16), Hiv2 is the digital value of the V-phase sensor signal obtained by performing a third correction process on the V-phase sensor signal Hiv1. In equation (17), Hiw2 is the digital value of the W-phase sensor signal obtained by performing a third correction process on the W-phase sensor signal Hiw1. Figure 7 shows an example of the waveforms of the sensor signals Hiu2, Hiv2, and Hiw2 obtained after performing the third correction process. In Figure 7, the vertical axis represents the digital value and the horizontal axis represents the electrical angle.

[0061] As described above, the basic patent method can reduce common-mode noise contained in the sensor signals Hu, Hv, and Hw through the first correction process. Furthermore, the basic patent method can correct the mutual variations of each sensor signal through the second correction process. Here, mutual variations refer to, for example, variations in the amplitude value and offset component of each sensor signal. Moreover, the basic patent method can straighten the curved portion of the waveform of each sensor signal through the third correction process. In particular, since the length of a portion of the sensor signal corresponding to a segment (divided signal) is made uniform by performing the second correction process, it is easier to apply a uniform calculation process to all divided signals in the third correction process. Therefore, by performing the second correction process before the third correction process, the curved portion of the waveform can be straightened more effectively. As a result, in the basic patent method, the signal portion (divided signal) required for calculating the estimated mechanical angle θ based on equation (1) above is more linearized, and the difference between the estimated mechanical angle θ and the true mechanical angle (for example, the mechanical angle indicated by the output signal of an encoder attached to the rotor shaft 110) can be reduced, thus enabling highly accurate mechanical angle estimation.

[0062] As described above, the basic patent method can reduce common-mode noise contained in each sensor signal Hu, Hv, and Hw through a first correction process. However, while it is ideal for the sensor signals Hiu0, Hiv0, and Hiw0 obtained after the first correction process to have a phase difference of 120 degrees in electrical angle, it may not be possible to precisely make the phase difference of the sensor signals Hiu0, Hiv0, and Hiw0 120 degrees because common-mode noise is reduced using equations (6), (7), and (8) above. Furthermore, the basic patent method can straighten the curved portion of the waveform of each sensor signal through a third correction process. However, in the third correction process, calculations expressed by equations (15), (16), and (17) above are performed using table data, but since the same table data is used for all curved portions (divided signals), errors may occur depending on the position of the divided signal.

[0063] Compared to the basic patent method described above, the present invention aims to further reduce the angular error between the estimated mechanical angle θ and the true mechanical angle, thereby improving the accuracy of detecting the mechanical angle of a rotating shaft.

[0064] The following describes the three-phase signal generation process performed by the processing unit 21 of the three-phase signal generation device 1 in this embodiment in order to solve the above technical problems.

[0065] Figure 8 is a flowchart showing the three-phase signal generation process performed by the processing unit 21 of the three-phase signal generation device 1 in this embodiment. The processing unit 21 performs the three-phase signal generation process shown in Figure 8 before performing the learning process of the basic patent method described above. More specifically, the processing unit 21 performs the three-phase signal generation process before performing the third correction process, without performing the first correction process and the second correction process.

[0066] As shown in Figure 8, the processing unit 21 rotates the sensor magnet 120 together with the rotor shaft 110 and acquires the instantaneous values ​​(digital values) of the sensor signals Hu, Hv, and Hw output from each magnetic sensor 11, 12, and 13 (step S1). This step S1 corresponds to the first step, and the processing performed in step S1 corresponds to the first processing. Hereafter, the instantaneous value of the U-phase sensor signal Hu is represented by Hu0(t), the instantaneous value of the V-phase sensor signal Hv is represented by Hv0(t), and the instantaneous value of the W-phase sensor signal Hw is represented by Hw0(t).

[0067] Next, the processing unit 21 calculates the U-phase complex vector (first complex vector), which is the complex vector of the U-phase sensor signal Hu, the V-phase complex vector (second complex vector), which is the complex vector of the V-phase sensor signal Hv, and the W-phase complex vector (third complex vector), which is the complex vector of the W-phase sensor signal Hw, based on the instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw (step S2). This step S2 corresponds to the second step, and the processing performed in step S2 corresponds to the second processing. Hereafter, the U-phase complex vector will be represented by Hu1(t), the V-phase complex vector by Hv1(t), and the W-phase complex vector by Hw1(t).

[0068] Figure 9 shows the instantaneous values ​​of the U-phase sensor signal Hu0(t), the V-phase sensor signal Hv0(t), the W-phase sensor signal Hw0(t), the U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) as vectors in the complex plane. In Figure 9, the horizontal axis is the real axis and the vertical axis is the imaginary axis. The U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) are vectors that rotate in the direction of the arrows with angular velocity ω(t) in the complex plane. The instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw are vectors whose absolute value (norm) and sign (direction of the vector) change on the real axis.

[0069] Although not shown in Figure 9, the instantaneous values ​​Hu0(t) of the U-phase sensor signal Hu, Hv0(t) of the V-phase sensor signal Hv, and Hw0(t) of the W-phase sensor signal Hw are each represented by a composite vector of the fundamental wave signal and the in-phase signal. The in-phase signal is a noise signal that includes DC signals and third-harmonic signals.

[0070] The U-phase complex vector Hu1(t) can be expressed using matrix A by the following equation (18).

[0071]

number

[0072] The V-phase complex vector Hv1(t) can be expressed using matrix A by the following equation (19).

[0073]

number

[0074] The W-phase complex vector Hw1(t) can be expressed using matrix A by the following equation (20).

[0075]

number

[0076] Matrix A is represented by the following equation (21).

[0077]

number

[0078] In other words, in step S2, the processing unit 21 calculates the U-phase complex vector Hu1(t), the V-phase complex vector Hv1(t), and the W-phase complex vector Hw1(t) based on the following calculation formulas (22), (23), and (24).

[0079]

number

[0080] Next, as shown in Figure 10, the processing unit 21 calculates the centroid of a triangle 31 in the complex plane, which has a line connecting the vertex of the U-phase complex vector Hu1(t) and the vertex of the W-phase complex vector Hw1(t) as one of its sides, as the first centroid Hu2(t) (step S3). This step S3 corresponds to the third step, and the processing performed in step S3 corresponds to the third processing. Note that the triangle 31, which has a line connecting the vertex of the U-phase complex vector Hu1(t) and the vertex of the W-phase complex vector Hw1(t) as one of its sides, may be an equilateral triangle or an isosceles triangle.

[0081] Furthermore, as shown in Figure 10, the processing unit 21 calculates the centroid of a triangle 32 in the complex plane, which has a line connecting the vertex of the U-phase complex vector Hu1(t) and the vertex of the V-phase complex vector Hv1(t) as one of its sides, as the second centroid Hv2(t) (step S4). This step S4 corresponds to the fourth step, and the processing performed in step S4 corresponds to the fourth processing. Note that the triangle 32, which has a line connecting the vertex of the U-phase complex vector Hu1(t) and the vertex of the V-phase complex vector Hv1(t) as one of its sides, may be an equilateral triangle or an isosceles triangle.

[0082] Furthermore, as shown in Figure 10, the processing unit 21 calculates the centroid of triangle 33, which has a line connecting the vertex of the V-phase complex vector Hv1(t) and the vertex of the W-phase complex vector Hw1(t) as one of its sides, as the third centroid Hw2(t) (step S5). This step S5 corresponds to the fifth step, and the processing performed in step S5 corresponds to the fifth processing. Note that triangle 33, which has a line connecting the vertex of the V-phase complex vector Hv1(t) and the vertex of the W-phase complex vector Hw1(t) as one of its sides, may be an equilateral triangle or an isosceles triangle.

[0083] Specifically, in the third step, the processing unit 21 calculates the first centroid Hu2(t) based on the following calculation formulas (25) and (28), in the fourth step, the second centroid Hv2(t) based on the following calculation formulas (26) and (29), and in the fifth step, the third centroid Hw2(t) based on the following calculation formulas (27) and (30).

[0084]

number

[0085] Next, the processing unit 21 calculates the centroid G'(t) of the triangle whose vertices are the first centroid Hu2(t), the second centroid Hv2(t), and the third centroid Hw2(t) (step S6). This step S6 corresponds to the sixth step, and the processing performed in step S6 corresponds to the sixth processing. As shown in Figure 10, the centroid G'(t) of the triangle whose vertices are the first centroid Hu2(t), the second centroid Hv2(t), and the third centroid Hw2(t) is different from the origin P0 of the complex plane. Specifically, in step S6, the processing unit 21 calculates the centroid G'(t) of the triangle whose vertices are the first centroid Hu2(t), the second centroid Hv2(t), and the third centroid Hw2(t) based on the following calculation formula (31).

[0086]

number

[0087] Then, as shown in Figure 11, the processing unit 21 corrects the U-phase complex vector Hu1(t), V-phase complex vector Hv1(t), and W-phase complex vector Hw1(t) by transforming the centroid G'(t) into the origin P0 of the complex plane (step S7). This step S7 corresponds to the seventh step, and the processing performed in step S7 corresponds to the seventh process. Specifically, in step S7, the processing unit 21 corrects the U-phase complex vector Hu1(t), V-phase complex vector Hv1(t), and W-phase complex vector Hw1(t) based on the following calculation formulas (32) to (34). See Figure 11 and the following calculation formulas (32) to (34). Hu3(t) represents the corrected U-phase complex vector, Hv3(t) represents the corrected V-phase complex vector, and Hw3(t) represents the corrected W-phase complex vector.

[0088]

number

[0089] In Figure 12, the upper graph shows an example of the waveforms for one electrical angle period, consisting of the instantaneous value Hu0(t) of the U-phase sensor signal Hu, the instantaneous value Hv0(t) of the V-phase sensor signal Hv, and the instantaneous value Hw0(t) of the W-phase sensor signal Hw. In Figure 12, the middle graph shows an example of the waveforms for one electrical angle period, consisting of the real part of the U-phase complex vector Hu1(t), the real part of the V-phase complex vector Hv1(t), and the real part of the W-phase complex vector Hw1(t). In Figure 12, the lower graph shows an example of the waveforms for one electrical angle period, consisting of the imaginary part of the U-phase complex vector Hu1(t), the imaginary part of the V-phase complex vector Hv1(t), and the imaginary part of the W-phase complex vector Hw1(t).

[0090] In Figure 13, the upper graph shows the norms of the U-phase complex vector Hu3(t), V-phase complex vector Hv3(t), and W-phase complex vector Hw3(t) obtained after the correction process in step S7. In Figure 13, the middle graph shows the arguments of the U-phase complex vector Hu3(t), V-phase complex vector Hv3(t), and W-phase complex vector Hw3(t) obtained after the correction process in step S7. In Figure 13, the lower graph shows the phase difference θuv between the U-phase complex vector Hu3(t) and the V-phase complex vector Hv3(t), the phase difference θvw between the V-phase complex vector Hv3(t) and the W-phase complex vector Hw3(t), and the phase difference θwu between the W-phase complex vector Hw3(t) and the U-phase complex vector Hu3(t).

[0091] As shown in Figure 13, the norms of the U-phase complex vector Hu3(t), V-phase complex vector Hv3(t), and W-phase complex vector Hw3(t) are all the same. Furthermore, the phase difference θuv between the U-phase complex vector Hu3(t) and the V-phase complex vector Hv3(t), the phase difference θvw between the V-phase complex vector Hv3(t) and the W-phase complex vector Hw3(t), and the phase difference θwu between the W-phase complex vector Hw3(t) and the U-phase complex vector Hu3(t) are all 120 degrees in electrical angles.

[0092] In this way, by performing the three-phase signal generation process, it is possible to obtain three-phase signals (U-phase complex vector Hu3(t), V-phase complex vector Hv3(t), and W-phase complex vector Hw3(t)) that have the same norm and a phase difference of 120 degrees in electrical angle from each other. Furthermore, the U-phase complex vector Hu3(t), V-phase complex vector Hv3(t), and W-phase complex vector Hw3(t) are signals from which common-phase signals have been removed, and signals from which mutual variations such as variations in amplitude values ​​and offset components have been corrected. In other words, by performing the three-phase signal generation process, it is possible to perform correction processing equivalent to the first and second correction processes, and to obtain three-phase signals with a precise phase difference of 120 degrees.

[0093] The processing unit 21 performs the above three-phase signal generation process to obtain the U-phase complex vector Hu3(t), the V-phase complex vector Hv3(t), and the W-phase complex vector Hw3(t), and then performs a third correction process on these three-phase signals which have a phase difference of exactly 120 degrees. In this case, even if the third correction process is performed using the same table data for all curve portions (divided signals) included in the three-phase signal, the error caused by the position of the divided signal can be reduced.

[0094] The processing unit 21 performs a third correction process on the U-phase complex vector Hu3(t), the V-phase complex vector Hv3(t), and the W-phase complex vector Hw3(t), and then executes a learning process of the basic patent method to obtain the correspondence between pole pair numbers, section numbers, and segment numbers, the characteristic data of each section, and the mechanical angle estimation formula for each segment, and stores these obtained data as learning data in the storage unit 22.

[0095] The angle estimation process performed by the processing unit 21 as an online process in this embodiment is basically the same as the angle estimation process in the basic patent method. However, the processing unit 21 in this embodiment differs from the basic patent method in that, when performing the angle estimation process, it obtains the U-phase complex vector Hu3(t), the V-phase complex vector Hv3(t), and the W-phase complex vector Hw3(t) by performing the three-phase signal generation process described above, and identifies the current section number and pole pair number based on these three-phase signals.

[0096] As described above, according to this embodiment, it is possible to obtain three-phase signals (U-phase complex vector Hu3(t), V-phase complex vector Hv3(t), and W-phase complex vector Hw3(t)) that have the same norm and a phase difference of 120 degrees in electrical angle from each other. Therefore, according to this embodiment, the angular error between the estimated mechanical angle θ and the true mechanical angle can be further reduced compared to the basic patent method disclosed in Japanese Patent No. 6233532, thereby improving the accuracy of mechanical angle detection of the rotating shaft. Furthermore, according to this embodiment, by converting the three-phase sensor signal from an instantaneous value (real number) to a complex vector, a geometrical approach (such as vector rotation and translation) becomes possible, and calculations can be easily performed on the complex plane without using elements that cause signal delay, such as filters.

[0097] (modified version) The present invention is not limited to the embodiments described above, and the configurations described herein can be combined as appropriate, within the bounds of non-inconsistency. For example, the above embodiment illustrates a combination of a motor 100 and a three-phase signal generator 1, but the present invention is not limited to this form, and a combination of a sensor magnet attached to a rotating shaft and a three-phase signal generator is also possible.

[0098] For example, in the above embodiment, the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 are arranged facing the disc-shaped sensor magnet 120 in the axial direction of the rotor shaft 110, but the present invention is not limited to this embodiment. For example, if a ring-shaped magnet is used instead of a disc-shaped sensor magnet, magnetic flux flows in the radial direction of the ring-shaped magnet, so the first magnetic sensor 11, the second magnetic sensor 12, and the third magnetic sensor 13 may be arranged facing the ring-shaped magnet in the radial direction of the ring-shaped magnet.

[0099] For example, in the above embodiment, a sensor magnet 120 attached to the rotor shaft 110 of the motor 100 was used as the rotating magnet, but a rotor magnet attached to the rotor of the motor 100 may also be used as the rotating magnet. The rotor magnet is also a magnet that rotates in sync with the rotor shaft 110 and has multiple magnetic pole pairs.

[0100] In the above embodiment, an example was given in which the sensor group 10 includes three magnetic sensors 11, 12, and 13. However, the number of magnetic sensors is not limited to three; any N sensors (where N is a multiple of 3) are acceptable. Also, in the above embodiment, an example was given in which the sensor magnet 120 has four magnetic pole pairs. However, the number of pole pairs of the sensor magnet 120 is not limited to four. Similarly, when a rotor magnet is used as a magnet for position detection, the number of pole pairs of the rotor magnet is not limited to four. [Explanation of Symbols]

[0101] 1...Three-phase signal generator, 10...Sensor group, 11...First magnetic sensor, 12...Second magnetic sensor, 13...Third magnetic sensor, 20...Signal processing unit, 21...Processing unit, 22...Storage unit, 100...Motor, 110...Rotor shaft, 120...Sensor magnet

Claims

1. A first magnetic sensor that faces a rotating magnet and outputs a first signal indicating the magnetic field strength, A second magnetic sensor that faces the magnet and outputs a second signal having a phase delay of 120° in electrical angle with respect to the first signal, A third magnetic sensor facing the magnet and outputting a third signal having a phase delay of 120° in electrical angle with respect to the second signal, A signal processing unit that processes the first signal, the second signal, and the third signal, Equipped with, The signal processing unit, A first process that obtains the instantaneous values ​​of the first signal, the second signal, and the third signal by digitally converting the first signal, the second signal, and the third signal, A second process that calculates a first complex vector which is the complex vector of the first signal, a second complex vector which is the complex vector of the second signal, and a third complex vector which is the complex vector of the third signal, based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third signal. A third process in which, in the complex plane, the centroid of a triangle having a line connecting the vertex of the first complex vector and the vertex of the third complex vector as one of its sides is calculated as the first centroid, A fourth process in which, in the complex plane, the centroid of a triangle having a line connecting the vertex of the first complex vector and the vertex of the second complex vector as one of its sides is calculated as the second centroid, A fifth process in which, in the complex plane, the centroid of a triangle having a line connecting the vertex of the second complex vector and the vertex of the third complex vector as one of its sides is calculated as the third centroid, A sixth process for calculating the centroid of a triangle having the first centroid, the second centroid, and the third centroid as its vertices, A seventh process that corrects the first complex vector, the second complex vector, and the third complex vector by transforming the centroid to the origin of the complex plane, Execute, A three-phase signal generator in which the triangle having a straight line connecting the vertex of the first complex vector and the vertex of the third complex vector as one side, the triangle having a straight line connecting the vertex of the first complex vector and the vertex of the second complex vector as one side, and the triangle having a straight line connecting the vertex of the second complex vector and the vertex of the third complex vector as one side are equilateral triangles or isosceles triangles.

2. The signal processing unit calculates the first complex vector, the second complex vector, and the third complex vector based on the calculation formulas (22), (23), and (24) in the second processing, Hu0(t) is the instantaneous value of the first signal, Hv0(t) is the instantaneous value of the second signal, Hw0(t) is the instantaneous value of the third signal, Hu1(t) is the first complex vector, Hv1(t) is the second complex vector, and Hw1(t) is the third complex vector. The three-phase signal generating device according to claim 1. [Math 1]

3. The signal processing unit calculates the first centroid in the third process based on calculation formulas (25) and (28), calculates the second centroid in the fourth process based on calculation formulas (26) and (29), and calculates the third centroid in the fifth process based on calculation formulas (27) and (30). Hu2(t) is the first centroid, Hv2(t) is the second centroid, and Hw2(t) is the third centroid. The three-phase signal generating device according to claim 2. [Math 2]

4. The signal processing unit calculates the centroid of the triangle having the first centroid, second centroid, and third centroid as vertices in the sixth process based on the calculation formula (31), G'(t) is the centroid mentioned above. The three-phase signal generating device according to claim 3. [Math 3]

5. The signal processing unit corrects the first complex vector, the second complex vector, and the third complex vector in the seventh process based on the calculation formulas (32) to (34). Hu3(t) is the first corrected complex vector, Hv3(t) is the second corrected complex vector, and Hw3(t) is the third corrected complex vector. The three-phase signal generating device according to claim 4. [Math 4]

6. A first magnetic sensor that faces a rotating magnet and outputs a first signal indicating the magnetic field strength, A second magnetic sensor that faces the magnet and outputs a second signal having a phase delay of 120° in electrical angle with respect to the first signal, A three-phase signal generation method using a third magnetic sensor that faces the magnet and outputs a third signal having a phase delay of 120° in electrical angle with respect to the second signal, The first step involves obtaining the instantaneous values ​​of the first signal, the second signal, and the third signal by digitally converting the first signal, the second signal, and the third signal; A second step of calculating a first complex vector which is the complex vector of the first signal, a second complex vector which is the complex vector of the second signal, and a third complex vector which is the complex vector of the third signal, based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third signal. In the complex plane, the third step is to calculate the centroid of a triangle having a line connecting the vertex of the first complex vector and the vertex of the third complex vector as one of its sides, and the centroid of the triangle is defined as the first centroid. In the complex plane, the fourth step is to calculate the centroid of a triangle having a line connecting the vertex of the first complex vector and the vertex of the second complex vector as one of its sides, and the centroid of the triangle is then calculated as the second centroid. In the complex plane, the fifth step is to calculate the centroid of a triangle having a line connecting the vertex of the second complex vector and the vertex of the third complex vector as one of its sides, and the centroid of the triangle is defined as the third centroid. A sixth step of calculating the centroid of a triangle having the first centroid, the second centroid, and the third centroid as its vertices, A seventh step involves correcting the first complex vector, the second complex vector, and the third complex vector by transforming the centroid to the origin of the complex plane, It has, A three-phase signal generation method wherein the triangle having a straight line connecting the vertex of the first complex vector and the vertex of the third complex vector as one side, the triangle having a straight line connecting the vertex of the first complex vector and the vertex of the second complex vector as one side, and the triangle having a straight line connecting the vertex of the second complex vector and the vertex of the third complex vector as one side are equilateral triangles or isosceles triangles.

7. In the second step, the first complex vector, the second complex vector, and the third complex vector are calculated based on the calculation formulas (22), (23), and (24). Hu0(t) is the instantaneous value of the first signal, Hv0(t) is the instantaneous value of the second signal, Hw0(t) is the instantaneous value of the third signal, Hu1(t) is the first complex vector, Hv1(t) is the second complex vector, and Hw1(t) is the third complex vector. The method for generating a three-phase signal according to claim 6. [Math 5]

8. In the third step, the first centroid is calculated based on calculation formulas (25) and (28); in the fourth step, the second centroid is calculated based on calculation formulas (26) and (29); and in the fifth step, the third centroid is calculated based on calculation formulas (27) and (30). Hu2(t) is the first centroid, Hv2(t) is the second centroid, and Hw2(t) is the third centroid. The method for generating a three-phase signal according to claim 7. [Math 6]

9. In the sixth step, the centroid of the triangle having the first centroid, the second centroid, and the third centroid as vertices is calculated based on the calculation formula (31), G'(t) is the centroid mentioned above. The method for generating a three-phase signal according to claim 8. [Number 7]

10. In the seventh step, the first complex vector, the second complex vector, and the third complex vector are corrected based on the calculation formulas (32) to (34), Hu3(t) is the first corrected complex vector, Hv3(t) is the second corrected complex vector, and Hw3(t) is the third corrected complex vector. The method for generating a three-phase signal according to claim 9. [Number 8]

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