CN117121363A - Position detection device and position detection method - Google Patents

Position detection device and position detection method Download PDF

Info

Publication number
CN117121363A
CN117121363A CN202180096395.8A CN202180096395A CN117121363A CN 117121363 A CN117121363 A CN 117121363A CN 202180096395 A CN202180096395 A CN 202180096395A CN 117121363 A CN117121363 A CN 117121363A
Authority
CN
China
Prior art keywords
signal
instantaneous value
phase
fundamental wave
synthesized
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202180096395.8A
Other languages
Chinese (zh)
Inventor
藤田淳
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nidec Corp
Original Assignee
Nidec Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nidec Corp filed Critical Nidec Corp
Publication of CN117121363A publication Critical patent/CN117121363A/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/244—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains
    • G01D5/245—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing characteristics of pulses or pulse trains; generating pulses or pulse trains using a variable number of pulses in a train
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
    • H02P6/14—Electronic commutators
    • H02P6/16—Circuit arrangements for detecting position

Abstract

One embodiment of the position detection device of the present invention includes three magnetic sensors and a signal processing unit that processes three-phase signals output from the three magnetic sensors. The signal processing section performs: an acquisition process of acquiring an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal; determining abnormality determination processing of an abnormality sensor, which is an abnormal magnetic sensor among the three magnetic sensors, by determining whether or not instantaneous values Hu ', hv ' of the U-phase signal and Hw ' of the W-phase signal satisfy expression (1) in all of the first case, the second case, and the third case; a signal generation process of generating a signal of the remaining one phase based on signals of two phases output from the two magnetic sensors other than the abnormality sensor; and a position estimation process of estimating a rotational position of the motor based on the two-phase signals output from the two magnetic sensors other than the abnormality sensor and the generated signal of the remaining one phase.

Description

Position detection device and position detection method
Technical Field
The present invention relates to a position detection device and a position detection method.
Background
Patent document 1 discloses a rotation detection device having two circuits for detecting rotation of a motor, which can continue a rotation detection operation even if an abnormality occurs in a part of the circuits.
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open No. 2017-191093
Disclosure of Invention
Problems to be solved by the invention
In the above-described prior art, the circuit required for detecting the rotation of the motor having two systems leads to an increase in the size of the apparatus and an increase in the component cost.
Means for solving the problems
One aspect of the position detection device of the present invention is a position detection device for detecting a rotational position of a motor, comprising: three magnetic sensors that are disposed opposite to a magnet that rotates in synchronization with the motor and are arranged at predetermined intervals along a rotation direction of the magnet; and a signal processing unit that processes three-phase signals having a phase difference of 120 DEG with respect to each other, which are output from the three magnetic sensors. The signal processing section performs: an acquisition process of acquiring an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal by respectively performing digital conversion on the U-phase signal, the V-phase signal, and the W-phase signal included in the three-phase signal; an abnormality determination process of determining whether or not an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal satisfy the following expression (1) in all of the first case, the second case, and the third case, thereby determining an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors; a signal generation process of generating a signal of the remaining one phase based on signals of two phases output from two magnetic sensors other than the abnormality sensor among the three magnetic sensors; and a position estimation process of estimating a rotational position of the motor based on two-phase signals output from the two magnetic sensors other than the abnormality sensor and the generated signal of the remaining one phase.
In one embodiment of the position detection method of the present invention, a method for detecting a rotational position of a motor using three-phase signals having a phase difference of 120 ° in electrical angle from each other, which are output from three magnetic sensors facing a magnet that rotates synchronously with the motor and are arranged at predetermined intervals in a rotational direction of the magnet, includes: an acquisition step of respectively performing digital conversion on a U-phase signal, a V-phase signal, and a W-phase signal included in the three-phase signal, thereby acquiring an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal; an abnormality determining step of determining whether or not an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal satisfy the following expression (1) in all of a first case, a second case, and a third case, thereby determining an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors; a signal generation step of generating a signal of the remaining one phase based on signals of two phases output from two magnetic sensors other than the abnormality sensor among the three magnetic sensors; and a position estimating step of estimating a rotational position of the motor based on two-phase signals output from the two magnetic sensors other than the abnormality sensor and the generated signal of the remaining one phase.
[ number 1]
(THmin-Hz')<(Hx'+Hy')<(THmax-Hz')…(1)
Where the first case is x=u, y=v, z=w, the second case is x=v, y=w, z=v, the third case is x=w, y=u, z=v, THmin is a minimum threshold, and THmax is a maximum threshold.
Effects of the invention
According to the above aspect of the present invention, there is provided a position detection device and a position detection method capable of continuing estimation of a rotational position of a motor by generating a signal of the remaining one phase based on signals of two phases output from two magnetic sensors other than an abnormality sensor even when an abnormality occurs in one of three magnetic sensors. Therefore, compared with the conventional technique of preparing circuits for detecting the rotation of the motors of the two systems, the miniaturization of the device and the reduction of the component cost can be realized.
Drawings
Fig. 1 is a block diagram schematically showing the structure of a position detecting device according to the present embodiment.
Fig. 2 is a diagram showing connection relations among three magnetic sensors, a power supply circuit, and a processing unit in the present embodiment.
Fig. 3 is a flowchart showing the respective processes executed by the processing unit of the position detection apparatus according to the present embodiment.
Fig. 4 is an explanatory diagram of abnormality determination processing executed by the processing unit of the position detection apparatus according to the present embodiment.
Fig. 5 is a flowchart showing a signal generation process executed by the processing unit of the position detection apparatus according to the present embodiment.
Fig. 6 is a diagram representing the first signal Hu 'and the second signal Hv' with vectors rotated on complex planes.
Fig. 7 is a diagram showing an example of waveform data of the first signal Hu 'obtained during one rotation of the vector of the first signal Hu' on the complex plane and waveform data of the second signal Hv 'obtained during one rotation of the vector of the second signal Hv' on the complex plane.
Fig. 8 is a diagram showing a composite signal Huv of the first fundamental wave signal Hu and the second fundamental wave signal Hv by a vector rotated on a complex plane.
Fig. 9 is a diagram showing an example of waveform data of the synthesized signal Huv obtained during one rotation of the vector of the first signal Hu 'and the second signal Hv' on the complex plane.
Fig. 10 is an explanatory diagram of a method of calculating the phase difference Φ1 between the first signal Hu 'and the second signal Hv' in the learning process.
Fig. 11 is an explanatory diagram of a method of calculating the phase difference Φ2 between the synthesized signal Huv and the first signal Hu' in the learning process.
Fig. 12 is an explanatory diagram showing a case where the phase difference between the synthesized signal Huv and the first fundamental wave signal Hu and the phase difference Φ2 between the synthesized signal Huv and the first signal Hu' are equal.
Fig. 13 is an explanatory diagram of the offset angle ωt+Φ2 of the synthesized signal Huv.
Fig. 14 is a diagram showing a third fundamental wave signal Hw in an orthogonal relationship with the synthesized signal Huv by a vector rotated on a complex plane.
Fig. 15 is a diagram showing an example of waveform data of the third fundamental wave signal Hw obtained during one rotation of the vector of the composite signal Huv on the complex plane.
Fig. 16 is a diagram showing an example of waveform data of the first fundamental wave signal Hu, waveform data of the second fundamental wave signal Hv, and waveform data of the third fundamental wave signal Hw.
Fig. 17 is a first explanatory diagram of the position estimation process executed by the processing unit of the position detection apparatus according to the present embodiment.
Fig. 18 is a second explanatory diagram of the position estimation process performed by the processing unit of the position detection apparatus according to the present embodiment.
Detailed Description
An embodiment of the present invention will be described in detail below with reference to the drawings.
Fig. 1 is a block diagram schematically showing the structure of a position detecting device 1 according to an embodiment of the present invention. As shown in fig. 1, the position detection device 1 is a device that detects a rotational position (rotation angle) of a motor 100. In the present embodiment, the motor 100 is, for example, an inner rotor type three-phase brushless DC motor. Motor 100 has a rotor shaft 110 and a sensor magnet 120. The rotor shaft 110 is a rotation shaft of the motor 100. The rotational position of the motor 100 refers to the rotational position of the rotor shaft 110.
The sensor magnet 120 is a disk-shaped magnet attached to the rotor shaft 110. The sensor magnet 120 is a magnet that rotates in synchronization with the rotor shaft 110. The sensor magnet 120 has P (P is an integer of 2 or more) magnetic pole pairs. In the present embodiment, as an example, the sensor magnet 120 has four pole pairs. The magnetic pole pair is a pair of an N pole and an S pole. That is, in the present embodiment, the sensor magnet 120 has four pairs of N and S poles, and has eight poles in total.
The position detection device 1 includes three magnetic sensors 11, 12, 13 and a signal processing unit 20. Although not shown in fig. 1, a circuit board is mounted on the motor 100, and the three magnetic sensors 11, 12, and 13 and the signal processing unit 20 are disposed on the circuit board. The sensor magnet 120 is disposed at a position not interfering with the circuit board. The sensor magnet 120 may be disposed inside the housing of the motor 100, or may be disposed outside the housing.
The magnetic sensors 11, 12, and 13 are disposed on the circuit board so as to face the sensor magnet 120 and at predetermined intervals along the rotation direction CW of the sensor magnet 120. In the present embodiment, the magnetic sensors 11, 12, and 13 are arranged at 30 ° intervals along the rotation direction CW of the sensor magnet 120. For example, the magnetic sensors 11, 12, and 13 are analog output type magnetic sensors including a magnetoresistive element, such as a hall element or a linear hall IC. The magnetic sensors 11, 12, and 13 each output an analog signal indicating the magnetic field strength that varies according to the rotational position of the rotor shaft 110, that is, the rotational position of the sensor magnet 120.
The electrical angle-period of each analog signal output from the magnetic sensors 11, 12, and 13 corresponds to 1/P of the mechanical angle-period. In the present embodiment, the pole pair number P of the sensor magnet 120 is "4", and thus the electrical angle-cycle of each analog signal corresponds to 1/4 of the mechanical angle-cycle, that is, the mechanical angle 90 °. In addition, the analog signals output from the magnetic sensors 11, 12, and 13 have a phase difference of 120 ° in electrical angle with each other.
Hereinafter, the analog signal output from the magnetic sensor 11 is referred to as a U-phase signal Hu ', the analog signal output from the magnetic sensor 12 is referred to as a V-phase signal Hv ', and the analog signal output from the magnetic sensor 13 is referred to as a W-phase signal Hw '. The V-phase signal Hv 'has a phase delay of 120 ° in electrical angle with respect to the U-phase signal Hu'. The W-phase signal Hw 'has a phase delay of 120 ° in electrical angle with respect to the V-phase signal Hv'.
As described above, the three magnetic sensors 11, 12, and 13 output signals of three phases having a phase difference of 120 ° in electrical angle from each other. The magnetic sensor 11 outputs the U-phase signal Hu' to the signal processing section 20. The magnetic sensor 12 outputs the V-phase signal Hv' to the signal processing section 20. The magnetic sensor 13 outputs the W-phase signal Hw' to the signal processing section 20.
The signal processing unit 20 is a signal processing circuit that processes three-phase signals having a phase difference of 120 ° in electrical angle from each other, which are output from the three magnetic sensors 11, 12, and 13. The signal processing unit 20 estimates the rotational position of the motor 100, that is, the rotational position of the rotor shaft 110, based on the U-phase signal Hu ' output from the magnetic sensor 11, the V-phase signal Hv ' output from the magnetic sensor 12, and the W-phase signal Hw ' output from the magnetic sensor 13. The signal processing unit 20 includes a power supply circuit 21, a processing unit 22, and a storage unit 23.
The power supply circuit 21 is a circuit for converting an external power supply voltage supplied from a dc power supply 200 such as a battery into an internal power supply voltage necessary for operating the internal circuits of the signal processing unit 20. As an example, the external power supply voltage supplied from the dc power supply 200 is 5V, and the internal power supply voltage outputted from the power supply circuit 21 is 3.3V. For example, as the power supply circuit 21, a low dropout regulator may be used.
The power supply circuit 21 is electrically connected to the processing unit 22 via a power supply line Vcc and a ground line GND. The power supply circuit 21 outputs an internal power supply voltage to the processing section 22 via the power supply line Vcc and the ground line GND. Although not shown in fig. 1, the power supply circuit 21 is also electrically connected to the storage unit 23 via a power supply line Vcc and a ground line GND.
The processing unit 22 is, for example, a microprocessor such as MCU (Microcontroller Unit). The U-phase signal Hu ' output from the magnetic sensor 11, the V-phase signal Hv ' output from the magnetic sensor 12, and the W-phase signal Hw ' output from the magnetic sensor 13 are input to the processing unit 22, respectively. The processing unit 22 is communicably connected to the storage unit 23 via a communication bus not shown. In detail, the processing unit 22 executes acquisition processing, abnormality determination processing, signal generation processing, and position estimation processing in accordance with a program stored in advance in the storage unit 23.
As shown in fig. 2, the processing unit 22 has three output ports P1, P2, and P3. The output ports P1, P2 and P3 are, for example, CMOS output ports. The output port P1 is electrically connected to the magnetic sensor 11 via a sensor power supply line Vcc 1. The output port P2 is electrically connected to the magnetic sensor 12 via a sensor power supply line Vcc 2. The output port P3 is electrically connected to the magnetic sensor 13 via the sensor power supply line Vcc 3. As shown in fig. 2, the power supply circuit 21 is electrically connected to the magnetic sensors 11, 12, and 13 via the ground line GND.
The processing unit 22 outputs the high-level voltage as the sensor power supply voltage from the output port P1 to the magnetic sensor 11. The processing unit 22 outputs the high-level voltage as the sensor power supply voltage from the output port P2 to the magnetic sensor 12. The processing unit 22 outputs the high-level voltage as the sensor power supply voltage from the output port P3 to the magnetic sensor 13. For example, in the case where the internal power supply voltage generated by the power supply circuit 21 is 3.3V, the high level voltage is 3.3V.
When the power supply to the magnetic sensor 11 is cut off, the processing unit 22 switches the output voltage of the output port P1 to a low level. When the power supply to the magnetic sensor 12 is cut off, the processing unit 22 switches the output voltage of the output port P2 to a low level. When the power supply to the magnetic sensor 13 is cut off, the processing unit 22 switches the output voltage of the output port P3 to a low level.
The storage unit 23 includes a nonvolatile memory that stores programs and various setting data and the like necessary for the processing unit 22 to execute various processes, and a volatile memory that is used as a temporary storage destination of data when the processing unit 22 executes various processes. The nonvolatile Memory is, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash Memory. The volatile memory is RAM (Random Access Memory), for example.
Next, the acquisition process, the abnormality determination process, the signal generation process, and the position estimation process performed by the processing unit 22 will be described.
When the power supply circuit 21 outputs the internal power supply voltage to the processing unit 22, the processing unit 22 starts and performs a predetermined initialization process, and then outputs high-level voltages from the output ports P1, P2, and P3, respectively. Thus, the sensor power supply voltage is supplied to each of the three magnetic sensors 11, 12, and 13, and each of the magnetic sensors 11, 12, and 13 is in a state in which the magnetic field intensity can be detected.
As shown in fig. 3, after the start of the power supply to the respective magnetic sensors 11, 12, and 13, the processing unit 22 performs acquisition processing (step S1) of respectively performing digital conversion on the U-phase signals Hu ', V-phase signals Hv', and W-phase signals Hw 'included in the three-phase signals output from the three magnetic sensors 11, 12, and 13, thereby acquiring instantaneous values of the U-phase signals Hu', V-phase signals Hv ', and W-phase signals Hw'. This step S1 corresponds to the acquisition step.
Specifically, an a/D converter is incorporated in the processing unit 22, and the processing unit 22 obtains an instantaneous value of the U-phase signal Hu ', an instantaneous value of the V-phase signal Hv', and an instantaneous value of the W-phase signal Hw 'as digital values by digitally converting the U-phase signal Hu', the V-phase signal Hv ', and the W-phase signal Hw' at predetermined sampling frequencies by the a/D converter, respectively.
Then, the processing section 22 performs an abnormality determination process (step S2) of determining an abnormal sensor, which is an abnormal magnetic sensor among the three magnetic sensors 11, 12, and 13, by determining whether or not the instantaneous value of the U-phase signal Hu ', the instantaneous value of the V-phase signal Hv ', and the instantaneous value of the W-phase signal Hw ' satisfy the following expression (1) in all of the first case, the second case, and the third case. This step S2 corresponds to an abnormality determination step.
[ number 2]
(THmin-Hz’)<(Hx’+Hy’)<(THmax-Hz')…(1)
Wherein, the first case: x=u, y=v, z=w
Second case: x=v, y=w, z=u
Third case: x=w, y=u, z=v
THmin: minimum threshold value
THmax: maximum threshold value
In the above formula (1), the minimum threshold value THmin and the maximum threshold value THmax are learning values obtained by the first learning process performed in advance, and are stored in advance in the nonvolatile memory of the storage unit 23. The first learning process will be described below.
Fig. 4 shows an example of time-series data of instantaneous values of U-phase signal Hu '(waveform data of U-phase signal Hu'), time-series data of instantaneous values of V-phase signal Hv '(waveform data of V-phase signal Hv'), and time-series data of instantaneous values of W-phase signal Hw '(waveform data of W-phase signal Hw'), which are obtained when all of the three magnetic sensors 11, 12, and 13 are normal. In fig. 4, the horizontal axis represents time and the vertical axis represents a digital value.
In the first learning process, the processing unit 22 calculates the maximum value Nzpn1 and the minimum value Nzpn2 of the three-phase unbalanced component Nzpn (=hu ' +hv ' +hw ') based on the waveform data of the three-phase signal obtained when the three magnetic sensors 11, 12, and 13 are normal as described above. Then, the processing unit 22 stores a value obtained by adding the set value Δth, which is the margin in design, to the maximum value Nzpn1 of the three-phase unbalanced component as the maximum threshold value THmax (=nzpn1+Δth) in the nonvolatile memory of the storage unit 23. The processing unit 22 also stores a value obtained by subtracting the set value Δth from the minimum Nzpn2 of the three-phase imbalance component as a minimum threshold value THmin (=nzpn 2- Δth) in the nonvolatile memory of the storage unit 23.
The above is a description of the first learning process. In step S2, the processing unit 22 reads out the maximum threshold value THmax and the minimum threshold value THmin from the nonvolatile memory of the storage unit 23, and determines whether or not the instantaneous value of the three-phase signal acquired in step S1 satisfies the equation (1) in all of the first case, the second case, and the third case, thereby determining the abnormality sensor from among the three magnetic sensors 11, 12, and 13.
As shown in fig. 4, when the magnetic sensor 13 is in a power-short state, for example, the instantaneous value of the W-phase signal Hw' output from the magnetic sensor 13 is fixed to a digital value indicating a high level (for example, 3.3V). When the magnetic sensor 13 is in a grounded shorted state, for example, the instantaneous value of the W-phase signal Hw' output from the magnetic sensor 13 is fixed to a digital value indicating a low level (for example, 0V). When the magnetic sensor 13 is in a failure state, for example, the waveform data of the W-phase signal Hw' output from the magnetic sensor 13 indicates an abnormal digital value different from the waveform data at the time of normal.
As described above, when the magnetic sensor 13 is in an abnormal state, for example, the expression (1) is not satisfied in the first case. In the first case, when the expression (1) is not satisfied, the processing unit 22 determines the magnetic sensor 13 as an abnormal sensor. Also, when the magnetic sensor 11 is in an abnormal state, the expression (1) is not satisfied in the second case. In the case where the equation (1) is not satisfied in the second case, the processing section 22 determines the magnetic sensor 11 as an abnormal sensor. In addition, when the magnetic sensor 12 is in an abnormal state, the expression (1) is not satisfied in the third case. In the third case, when the expression (1) is not satisfied, the processing unit 22 determines the magnetic sensor 12 as an abnormal sensor.
When the abnormality determination processing in step S2 determines an abnormality sensor, the processing unit 22 cuts off the power supply to the abnormality sensor among the three magnetic sensors 11, 12, and 13. For example, when the magnetic sensor 11 is an abnormal sensor, the processing unit 22 switches the output voltage of the output port P1 to a low level, thereby shutting off the power supply to the magnetic sensor 11. When the magnetic sensor 12 is an abnormal sensor, the processing unit 22 switches the output voltage of the output port P2 to a low level, thereby shutting off the power supply to the magnetic sensor 12. When the magnetic sensor 13 is an abnormal sensor, the processing unit 22 switches the output voltage of the output port P3 to a low level, thereby shutting off the power supply to the magnetic sensor 13.
Then, the processing section 22 performs a signal generation process (step S3) of generating a signal of the remaining one phase based on the signals of two phases output from the two magnetic sensors other than the anomaly sensor out of the three magnetic sensors 11, 12, and 13. This step S3 corresponds to a signal generation step. Hereinafter, one of the two-phase signals output from the two magnetic sensors other than the abnormality sensor is set as a first signal, and the other signal having a phase delay of 120 ° in electrical angle with respect to the first signal is set as a second signal. For example, when the magnetic sensor 13 is an anomaly sensor, the U-phase signal Hu 'output from the magnetic sensor 11 is a first signal, and the V-phase signal Hv' output from the magnetic sensor 12 is a second signal.
When the sensor magnet 120 rotates together with the rotor shaft 110, a first signal Hu ' representing the intensity of a magnetic field varying according to the rotational position of the sensor magnet 120 is output from the magnetic sensor 11, and a second signal Hv ' having a phase delay of 120 ° in electrical angle with respect to the first signal Hu ' is output from the magnetic sensor 12. The processing section 22 digitally converts the first signal Hu 'and the second signal Hv' at a predetermined sampling frequency by an a/D converter. The processing section 22 executes the signal generation processing shown in the flowchart of fig. 5 every time the execution timing of the digital conversion, that is, the sampling timing has come.
As shown in fig. 5, when the sampling timing arrives, the processing unit 22 performs digital conversion on the first signal Hu 'and the second signal Hv' output to the processing unit 22 in association with the rotation of the sensor magnet 120 as described above, thereby obtaining the instantaneous value of the first signal Hu 'and the instantaneous value of the second signal Hv' as digital values (step S11). This step S11 corresponds to the first step, and the processing performed in step S11 corresponds to the first processing.
Fig. 6 is a diagram representing the first signal Hu 'and the second signal Hv' with vectors rotated on complex planes. In fig. 6, the horizontal axis is the real axis, and the vertical axis is the imaginary axis. The first signal Hu 'and the second signal Hv' rotate in the direction of the arrow at an angular velocity ω on the complex plane. As shown in fig. 6, the first signal Hu' includes a first fundamental wave signal Hu as a fundamental wave signal and an in-phase signal N. The first signal Hu' is represented by a composite vector of the first fundamental wave signal Hu and the in-phase signal N. That is, the first signal Hu' is represented by the following formula (2). The second signal Hv' includes a second fundamental wave signal Hv and an in-phase signal N as fundamental wave signals. The second signal Hv' is represented by a composite vector of the second fundamental wave signal Hv and the in-phase signal N. That is, the second signal Hv' is represented by the following equation (3). The in-phase signal N is a noise signal including a direct current signal, a third harmonic signal, and the like.
[ number 3]
Hu’＝Hu+N…(2)
Hv'＝Hv+N…(3)
The instantaneous value of the first signal Hu 'acquired in step S11 corresponds to the real part (the part projected onto the real axis) of the first signal Hu' represented by a vector in fig. 6. Similarly, the instantaneous value of the second signal Hv 'acquired in step S11 corresponds to the real part of the second signal Hv' represented by a vector in fig. 6. For example, the instantaneous value of the first signal Hu' is represented by the following equation (4). In the following expression (4), hu 'is a norm of the first signal Hu', and k is an integer of 1 or more.
[ number 4]
Hu’＝||Hu’||·cos(ωkt)…(4)
Fig. 7 is a diagram showing an example of time-series data of an instantaneous value of the first signal Hu '(waveform data of the first signal Hu') obtained during one rotation of the vector of the first signal Hu 'on the complex plane and time-series data of an instantaneous value of the second signal Hv' (waveform data of the second signal Hv ') obtained during one rotation of the vector of the second signal Hv' on the complex plane. In fig. 7, the horizontal axis represents time and the vertical axis represents a digital value. As shown in fig. 7, the waveforms of the first signal Hu 'and the second signal Hv' including the in-phase signal N are not completely sinusoidal waveforms, but have distorted waveforms.
Returning to fig. 5, the processing unit 22 subtracts the instantaneous value of the second signal Hv ' from the instantaneous value of the first signal Hu ' to calculate the instantaneous value of the synthesized signal Huv of the first fundamental wave signal Hu and the second fundamental wave signal Hv included in the first signal Hu ' (step S12). This step S12 corresponds to the second step, and the processing performed in step S12 corresponds to the second processing.
As shown in the following equation (5), the instantaneous value of the second fundamental wave signal Hv 'is subtracted from the instantaneous value of the first signal Hu', whereby the in-phase signal N included in the two signals is canceled, and the instantaneous value of the synthesized signal Huv of the first fundamental wave signal Hu and the second fundamental wave signal Hv is obtained. Fig. 8 is a diagram showing a composite signal Huv of the first fundamental wave signal Hu and the second fundamental wave signal Hv by a vector rotated on a complex plane. Fig. 9 is a diagram showing an example of time-series data (waveform data of the synthesized signal Huv) of an instantaneous value of the synthesized signal Huv obtained during one rotation of the vector of the first signal Hu 'and the second signal Hv' on the complex plane. As shown in fig. 9, the waveform of the synthesized signal Huv is a completely sinusoidal waveform.
[ number 5]
Huv＝Hu’-Hv’
＝Hu+N-Hv-N
＝Hu-Hv…(5)
In step S12, the processing unit 22 corrects at least one of the instantaneous value of the first signal Hu 'and the instantaneous value of the second signal Hv' based on the amplitude correction value prepared in advance before calculating the instantaneous value of the synthesized signal Huv. The amplitude correction value is a correction value for equalizing the amplitude value of the first signal Hu 'and the amplitude value of the second signal Hv'. The amplitude correction value is one of the learning values obtained by the second learning process performed in advance, and is stored in the nonvolatile memory of the storage unit 23 in advance. That is, in step S12, the processing unit 22 reads out the amplitude correction value from the nonvolatile memory of the storage unit 23, and corrects at least one of the instantaneous value of the first signal Hu 'and the instantaneous value of the second signal Hv' based on the read-out amplitude correction value so that the amplitude value of the first signal Hu 'and the amplitude value of the second signal Hv' are equal.
Returning to fig. 5, the processing unit 22 calculates the offset angle of the synthesized signal Huv based on the instantaneous value of the synthesized signal Huv and the norm of the synthesized signal Huv prepared in advance (step S13). This step S13 corresponds to a third step, and the processing performed in step S13 corresponds to a third processing.
The norm of the synthesized signal Huv is one of the learning values obtained by the second learning process performed in advance, and is stored in the nonvolatile memory of the storage unit 23 in advance, similarly to the amplitude correction value described above. In addition to the amplitude correction value and the norm of the synthesized signal Huv, the phase difference between the synthesized signal Huv and the first fundamental wave signal Hu is stored in the nonvolatile memory of the storage unit 23 as a learning value. The second learning process performed in advance will be described below.
The second learning process is performed in a state in which the sensor magnet 120 rotates together with the rotor shaft 110. In the second learning process, the processing unit 22 repeats the processing of steps S11 and S12 at a predetermined sampling frequency until at least a period corresponding to the electrical angle of the first signal Hu 'and the second signal Hv' elapses, that is, until at least the sensor magnet 120 rotates by a mechanical angle of 90 °. In other words, the processing unit 22 repeats the processing of the above steps S11 and S12 at a predetermined sampling frequency until the vector of the first signal Hu 'and the second signal Hv' rotates at least once on the complex plane.
Thus, the processing unit 31 sequentially acquires the instantaneous value of the first signal Hu ', the instantaneous value of the second signal Hv' and the instantaneous value of the synthesized signal Huv, compares the maximum value of each instantaneous value in the past with each instantaneous value at the current time (current sampling timing), and performs processing to update the maximum value of each instantaneous value in the past to each instantaneous value at the current time when each instantaneous value at the current time is larger than the maximum value of each instantaneous value in the past. The processing unit 31 sequentially obtains the instantaneous value of the first signal Hu ', the instantaneous value of the second signal Hv' and the instantaneous value of the synthesized signal Huv, compares the minimum value of each instantaneous value in the past with each instantaneous value at the current time, and performs a process of updating the minimum value of each instantaneous value in the past to each instantaneous value at the current time when each instantaneous value at the current time is smaller than the minimum value of each instantaneous value in the past.
The processing unit 22 obtains the maximum value and the minimum value of each signal by performing the sequential update processing as described above. Then, the processing unit 22 substitutes the maximum value Max (Hu ') and the minimum value Min (Hu ') of the first signal Hu ' into the following equation (6), thereby calculating the norm ||hu ' | as the amplitude value of the first signal Hu '. The processing unit 22 substitutes the maximum value Max (Hv ') and the minimum value Min (Hv') of the second signal Hv 'into the following expression (7), thereby calculating the norm of the amplitude value of the second signal Hv'. The processing unit 22 substitutes the maximum value Max (Huv) and the minimum value Min (Huv) of the synthesized signal Huv into the following expression (8), calculated as a composite signal Huv norms of the amplitude values are Huv.
[ number 6]
||Hu’||＝{Max(Hu’)-Min(Hu’)}/2…(6)
||Hv’||＝{Max(Hv')-Min(Hv')}/2…(7)
||Huv||＝{Max(Huv)-Min(Huv)}/2…(8)
The processing unit 22 calculates an amplitude correction value that makes the norm Hu 'of the first signal Hu' equal to the norm Hv 'of the second signal Hv'. The processing unit 22 corrects at least one of all instantaneous values included in the waveform data of the first signal Hu 'and all instantaneous values included in the waveform data of the second signal Hv' by the amplitude correction value. Thereby, waveform data of the first signal Hu 'and waveform data of the second signal Hv' having equal amplitude values (norms) are obtained.
As shown in fig. 10, the processing unit 22 calculates a phase difference Φ1 (≡yp-120 °) between the first signal Hu ' and the second signal Hv ' based on the first signal Hu ' based on the waveform data of the first signal Hu ' and the waveform data of the second signal Hv ' after the amplitude correction. Specifically, as shown in fig. 10, the processing unit 22 calculates the phase difference Φ1 by counting the time between the maximum value Max (Hu ') of the first signal Hu' and the maximum value Max (Hv ') of the second signal Hv' by a reference encoder or the like, and substituting the count result Nmax into the following equation (9). Alternatively, the processing unit 22 may calculate the phase difference Φ1 by counting the time between the minimum value Min (Hu ') of the first signal Hu' and the minimum value Min (Hv ') of the second signal Hv' by using a reference encoder or the like, and substituting the count result Nmin into the following expression (10). In the formulas (9) and (10), ncpr is the resolution of the reference encoder. In the second learning process, the reference encoder is mounted on the rotation shaft in advance.
[ number 7]
As shown in fig. 11, the processing unit 22 calculates a phase difference Φ2 (++30°) between the synthesized signal Huv and the first signal Hu ' based on the phase difference Φ1 between the first signal Hu ' and the second signal Hv '. Specifically, the processing unit 22 substitutes the phase difference Φ1 between the first signal Hu ' and the second signal Hv ' into the following equation (11), thereby calculating the phase difference Φ2 between the synthesized signal Huv and the first signal Hu '.
[ number 8]
As shown in fig. 12, the phase difference Φ2 between the synthesized signal Huv and the first signal Hu' and the phase difference between the synthesized signal Huv and the first fundamental wave signal Hu are equal. Therefore, the processing unit 22 obtains the phase difference Φ2 between the composite signal Huv and the first fundamental wave signal Hu' as the phase difference between the composite signal Huv and the first fundamental wave signal Hu. By the second learning process as described above, the amplitude correction value, the norm of the synthesized signal Huv Huv, and the phase difference Φ2 between the synthesized signal Huv and the first fundamental wave signal Hu are obtained as the learning values. The processing unit 22 stores each learning value obtained by the second learning process in the nonvolatile memory of the storage unit 23.
The second learning process is described above, and the description of the signal generation process is continued by returning to fig. 5. In step S13 of fig. 5, the processing section 22 calculates the instantaneous value of the synthesized signal Huv calculated in step S12 and the norm of the synthesized signal Huv obtained in advance by the second learning process, the offset angle of the resultant signal Huv is calculated. As shown in fig. 13, when the offset angle of the synthesized signal Huv is set to ωt+Φ2, the instantaneous value of the synthesized signal Huv is expressed by the following expression (12).
[ number 9]
Therefore, in step S13, the processing unit 22 calculates the offset angle ωt+Φ2 of the synthesized signal Huv based on the following expression (13). That is, the processing unit 22 reads out the norm | Huv | of the synthesized signal Huv from the nonvolatile memory of the storage unit 23, and substitutes the instantaneous value of the synthesized signal Huv calculated in step S12 and the norm | Huv | of the read-out synthesized signal Huv into the following equation (13), thereby calculating the offset angle ωt+Φ2 of the synthesized signal Huv.
However, the offset angle ωt+Φ2 of the synthesized signal Huv obtained by the expression (13) is limited to a value of 0 ° or more and 180 ° or less. Therefore, the sine value of the offset angle ωt+Φ2 is limited to a positive polarity value of 0 or more and 1 or less. Therefore, in the present embodiment, the processing unit 22 performs the expansion processing on the calculated offset angle ωt+Φ2, thereby obtaining the offset angle θ included in the range of-180 ° or more and less than 180 °. Thus, the sine value of the offset angle θ is in the range of-1 to 1, and both positive and negative polarity values are obtained.
[ number 10]
Wherein, -1 is less than or equal to (Huv/|) Huv is less than or equal to 1)
0≤(ωt+φ2)≤+180°
Then, the processing section 22 generates a first fundamental wave signal Hu based on the offset angle θ of the synthesized signal Huv, the norm of the synthesized signal Huv Huv, and the phase difference phi 2 between the synthesized signal Huv and the first fundamental wave signal Hu prepared in advance, an instantaneous value of the third fundamental wave signal Hw having an orthogonal relationship with the synthesized signal Huv is calculated (step S14). This step S14 corresponds to a fourth step, and the processing performed in step S14 corresponds to a fourth processing.
Fig. 14 is a diagram showing a third fundamental wave signal Hw having an orthogonal relationship with the composite signal Huv by a vector rotating on a complex plane. When the condition that the amplitude value (|hu '|) of the first signal Hu' and the amplitude value (|hv '|) of the second signal Hv' are equal to each other by the amplitude correction is satisfied, the amplitude value (|hu|) of the first fundamental wave signal Hu and the amplitude value (|hv|) of the second fundamental wave signal Hv are equal to each other. In this case, the ratio of the norm of the synthesized signal Huv Huv to the norm of the third fundamental wave signal Hw is 1/2sin (Φ2). Accordingly, the instantaneous value of the third fundamental wave signal Hw having an orthogonal relationship with the synthesized signal Huv is expressed by the following equation (14).
In step S14, the processing unit 22 reads out the norm | Huv | and the phase difference Φ2 of the synthesized signal Huv from the nonvolatile memory of the storage unit 23, and substitutes the norm | Huv | and the phase difference Φ2 of the synthesized signal Huv and the offset angle θ acquired in step S13 into the following equation (14), thereby calculating the instantaneous value of the third fundamental wave signal Hw. Fig. 15 is a diagram showing an example of time-series data of an instantaneous value of the third fundamental wave signal Hw (waveform data of the third fundamental wave signal Hw) obtained during one rotation of the vector of the composite signal Huv on the complex plane. As shown in fig. 15, the waveform of the third fundamental wave signal Hw is a complete sinusoidal waveform as is the case with the synthesized signal Huv, the first fundamental wave signal Hu, and the second fundamental wave signal Hv.
[ number 11]
Wherein Φ2=yp.30° > 0 °
Returning to fig. 5, the processing unit 22 calculates the instantaneous values of the in-phase signal N contained in the first signal Hu 'and the second signal Hv' based on the instantaneous values of the first signal Hu ', the second signal Hv', and the third fundamental wave signal Hw (step S15). This step S15 corresponds to a fifth step, and the processing performed in step S15 corresponds to a fifth process. Specifically, in step S15, the processing unit 22 calculates the instantaneous value of the in-phase signal N based on the following equations (15) and (16).
[ number 12]
Hw'＝-(Hu’+Hv')…(15)
N＝-(Hw’-Hw)/2…(16)
In step S15, the processing unit 22 first substitutes the instantaneous value of the first signal Hu ' and the instantaneous value of the second signal Hv ' into the above equation (15), thereby calculating the instantaneous value of the third signal Hw '. The third signal Hw 'is a signal satisfying three-phase balance (Hu' +hv '+hw' =0) together with the first signal Hu 'and the second signal Hv'. In other words, the third signal Hw ' is a signal having a phase delay of 240 ° electrical angle with respect to the first signal Hu ' and a phase delay of 120 ° electrical angle with respect to the second signal Hv '.
As shown in fig. 14, when the third signal Hw ' is represented by a vector rotated on the complex plane, the third signal Hw ' is represented by a vector (Hw ' =hw-2N) in which a vector of the third fundamental wave signal Hw and a vector of minus twice the in-phase signal N are combined. Therefore, the in-phase signal N can be represented by the above equation (16). In step S15, the processing unit 22 substitutes the instantaneous value of the third signal Hw' calculated in accordance with the equation (15) and the instantaneous value of the third fundamental wave signal Hw calculated in step S14 into the equation (16), thereby calculating the instantaneous value of the in-phase signal N. Fig. 15 shows an example of the waveform of the third signal Hw' and the waveform of the in-phase signal N.
Returning to fig. 5, the processing unit 22 calculates an instantaneous value of the first fundamental wave signal Hu by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the first signal Hu' (step S16). This step S16 corresponds to a sixth step, and the processing performed in step S16 corresponds to a sixth process. Referring to equation (2), it can be easily understood that the instantaneous value of the first fundamental wave signal Hu can be calculated by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the first signal Hu'.
Finally, the processing unit 22 calculates an instantaneous value of the second fundamental wave signal Hv by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the second signal Hv' (step S17). This step S17 corresponds to a seventh step, and the processing performed in step S17 corresponds to a seventh process. Referring to equation (3), it can be easily understood that the instantaneous value of the second fundamental wave signal Hv can be calculated by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the second signal Hv'.
The processing unit 22 executes signal generation processing including the processing from step S11 to step S17 described above every time the sampling timing arrives. As a result, as shown in fig. 16, time-series data of the instantaneous value of the first fundamental wave signal Hu (waveform data of the first fundamental wave signal Hu), time-series data of the instantaneous value of the second fundamental wave signal Hv (waveform data of the second fundamental wave signal Hv), and time-series data of the instantaneous value of the third fundamental wave signal Hw (waveform data of the third fundamental wave signal Hw) are obtained. As shown in fig. 16, the waveforms of the first fundamental wave signal Hu, the second fundamental wave signal Hv, and the third fundamental wave signal Hw are completely sinusoidal waveforms. In addition, the first fundamental wave signal Hu, the second fundamental wave signal Hv, and the third fundamental wave signal Hw have a phase difference of 120 ° in electrical angle from each other.
By the signal generation processing described above, it is possible to generate three-phase fundamental wave signals having a phase difference of 120 ° in electrical angle from each other based on two-phase signals output from two magnetic sensors other than the anomaly sensor out of the three magnetic sensors 11, 12, and 13.
Returning to fig. 3, the processing unit 22 performs a position estimation process (step S4) of estimating the rotational position of the motor 100 based on the two-phase signals output from the two magnetic sensors other than the abnormality sensor and the generated signal of the remaining one phase. That is, the processing unit 22 estimates the rotational position of the motor 100 based on the three-phase fundamental wave signals Hu, hv, and Hw having a 120 ° electrical angle phase difference from each other. This step S4 corresponds to a position estimation step.
In order to obtain a learning value necessary for estimating the rotational position of the motor 100, a third learning process is performed in advance. The following describes a third learning process performed in advance. The third learning process is performed in a state where all of the magnetic sensors 11, 12, and 13 are normal.
In the third learning process, the processing unit 22 obtains waveform data (time-series data of instantaneous values) of each of the U-phase signal Hu ', the V-phase signal Hv ' and the W-phase signal Hw ' in a state where the sensor magnet 120 rotates together with the rotor shaft 110. Then, based on the three waveform data, the processing section 22 calculates waveform data of the first fundamental wave signal Hu included in the U-phase signal Hu ', waveform data of the second fundamental wave signal Hv included in the V-phase signal Hv ', and waveform data of the third fundamental wave signal Hw included in the W-phase signal Hw '. As an operation formula for extracting the fundamental wave signal from each of the three phase signals output from the three magnetic sensors 11, 12, and 13, for example, the formulas (1), (2), and (3) described in japanese patent No. 6233532 can be used.
As shown in fig. 17, the processing unit 22 divides the mechanical angle into four pole pair regions associated with pole pair numbers indicating the pole pair positions of the four pole pairs in one cycle based on waveform data of the three fundamental wave signals Hu, hv and Hw, divides the four pole pair regions into a plurality of segments, and associates segment numbers indicating the rotational positions of the rotor shaft 110 with the plurality of segments, respectively.
In the present embodiment, in order to estimate the rotational position of the rotor shaft 110, the four magnetic pole pairs of the sensor magnet 120 are assigned with a magnetic pole pair number indicating the position of the magnetic pole pair. For example, the four pole pairs of sensor magnet 120 are numbered in the order "0", "1", "2", "3" around clockwise as shown in fig. 1.
As shown in fig. 17, the processing unit 22 divides the mechanical angle into four pole pair regions in one cycle based on waveform data of the fundamental wave signals Hu, hv and Hw obtained in one cycle of the mechanical angle. In fig. 17, the period from time t1 to time t5 corresponds to one cycle of the mechanical angle. In fig. 17, "No. c" indicates the pole pair number.
The processing unit 22 divides the period from time t1 to time t2 in the mechanical angle cycle into pole pair regions associated with the pole pair number "0".
The processing unit 22 divides the period from time t2 to time t3 in the mechanical angle cycle into pole pair regions associated with the pole pair number "1".
The processing unit 22 divides the period from time t3 to time t4 in the mechanical angle cycle into pole pair regions associated with the pole pair number "2".
The processing unit 22 divides the period from time t4 to time t5 in the mechanical angle cycle into pole pair regions associated with the pole pair number "3".
As shown in fig. 17, the processing unit 22 further divides each of the four pole pair regions into 12 segments based on waveform data of the fundamental wave signals Hu, hv, and Hw obtained in a mechanical angle cycle, and associates segment numbers indicating rotational positions of the rotor shaft 110 with each of the 12 segments. In fig. 17, "No. a" represents a section number assigned to a section, and "No. b" represents a section number.
As shown in fig. 17, 12 segments contained in each of the four pole pair regions are assigned segment numbers from "0" to "11". On the other hand, a number continuous throughout one cycle of the mechanical angle is associated with each segment as a segment number. Specifically, as shown in fig. 17, in the pole pair region associated with the pole pair number "0", segment numbers "0" to "11" are associated with segment numbers "0" to "11". In the pole pair region associated with the pole pair number "1", segment numbers "12" to "23 are associated with segment numbers" 0 "to" 11 ". In the pole pair region associated with the pole pair number "2", segment numbers "24" to "35" are associated with segment numbers "0" to "11". In the pole pair region associated with the pole pair number "3", segment numbers "36" to "47" are associated with segment numbers "0" to "11".
Fig. 18 is an enlarged view of fundamental wave signals Hu, hv and Hw contained in one pole pair region. Hereinafter, a method of dividing the pole pair region into 12 segments will be described with reference to fig. 18. In fig. 18, the reference value of the amplitude is "0". In fig. 18, as an example, a digital value of the amplitude of a positive value indicates a digital value of the magnetic field strength of the N pole. Further, as an example, a digital value of the amplitude of the negative value represents a digital value of the magnetic field strength of the S pole.
The processing unit 22 extracts zero-crossing points, which are points at which the three fundamental wave signals Hu, hv and Hw included in each of the four pole pair regions cross the reference value "0". As shown in fig. 18, the processing unit 22 extracts the point P1, the point P3, the point P5, the point P7, the point P9, the point P11, and the point P13 as zero-crossing points.
Then, the processing unit 22 extracts an intersection point, which is a point at which the three fundamental wave signals Hu, hv and Hw included in each of the four pole pair regions intersect with each other. As shown in fig. 18, the processing unit 22 extracts the points P2, P4, P6, P8, P10, and P12 as the intersections. Then, the processing unit 22 determines the section between the zero-crossing points adjacent to each other as a node.
As shown in fig. 18, the processing unit 22 determines a section between the zero-crossing point P1 and the crossing point P2 as a section to which the section number "0" is assigned.
The processing unit 22 determines a section between the intersection P2 and the zero-crossing point P3 as a section to which the section number "1" is assigned.
The processing unit 22 determines a section between the zero-crossing point P3 and the crossing point P4 as a section to which the section number "2" is assigned.
The processing unit 22 determines a section between the intersection P4 and the zero-crossing point P5 as a section to which the section number "3" is assigned.
The processing unit 22 determines a section between the zero-crossing point P5 and the crossing point P6 as a section to which the section number "4" is assigned.
The processing unit 22 determines a section between the intersection P6 and the zero-crossing point P7 as a section to which the section number "5" is assigned.
The processing unit 22 determines a section between the zero-crossing point P7 and the crossing point P8 as a section to which the section number "6" is assigned.
The processing unit 22 determines a section between the intersection P8 and the zero-crossing point P9 as a section to which the section number "7" is assigned.
The processing unit 22 determines a section between the zero-crossing point P9 and the crossing point P10 as a section to which the section number "8" is assigned.
The processing unit 22 determines a section between the intersection P10 and the zero-crossing point P11 as a section to which the section number "9" is assigned.
The processing unit 22 determines a section between the zero-crossing point P11 and the crossing point P12 as a section to which the section number "10" is assigned.
The processing unit 22 determines a section between the intersection P12 and the zero-crossing point P13 as a section to which the section number "11" is assigned.
Further, the processing unit 22 extracts, for each section, feature data such as the magnitude relation of instantaneous values (digital values) of the fundamental wave signals Hu, hv and Hw and the sign of each instantaneous value, and associates the extracted feature data with the section number of each section.
By executing the above-described processing, as shown in fig. 17, the mechanical angle is divided into four pole pair regions associated with pole pair numbers for one cycle, the four pole pair regions are divided into 12 segments, and segment numbers are associated with segment numbers of the segments, respectively. In the following description, for example, a section to which a section number "0" is assigned is referred to as a "number 0 section", and a section to which a section number "11" is assigned is referred to as a "number 11 section".
The processing unit 22 acquires feature data associated with the segment number and data indicating a correspondence relationship between the segment number associated with the segment number and indicating the rotational position and the pole pair number indicating the pole pair position as learning data, and stores the acquired learning data in the storage unit 23. The above is a description of the third learning process.
In step S4, when the position estimation processing is started, the processing unit 22 first identifies the current segment from the 12 segments based on the instantaneous values of the fundamental wave signals Hu, hv and Hw obtained in step S3. For example, in fig. 18, it is assumed that a point PHu located on the waveform of the first fundamental wave signal Hu, a point PHv located on the waveform of the second fundamental wave signal Hv, and a point PHw located on the waveform of the third fundamental wave signal Hw are instantaneous values of the respective fundamental wave signals Hu, hv, and Hw obtained at arbitrary sampling timings. The processing unit 22 extracts feature data such as the magnitude relation of the instantaneous values at the points PHu, PHv and PHw and the sign of the positive or negative of each instantaneous value, and compares the extracted feature data with learning data stored in the storage unit 23, thereby specifying the segment number associated with the feature data matching the extracted feature data as the current segment. In the example of fig. 18, section No. 9 is determined as the current section.
Then, the processing unit 22 determines the current segment number as the rotational position of the motor 100 based on the determined current segment (segment number) and the learning data stored in the storage unit 23. For example, as described above, assume that section No. 9 is determined as the current section. Further, it is assumed that the pole pair number at the time of obtaining the instantaneous values of the points PHu, PHv, and PHw is "2". In this case, as shown in fig. 17, the processing unit 22 determines the segment number "33" as the rotational position of the motor 100.
As described above, the position detection device of the present embodiment includes: three magnetic sensors disposed opposite to the magnet rotating synchronously with the motor and at predetermined intervals along the rotation direction of the magnet; and a signal processing unit that processes three-phase signals that are output from the three magnetic sensors and have a phase difference of 120 DEG electrical angle from each other. The signal processing section performs: an acquisition process of acquiring instantaneous values Hu ', hv ' and Hw ' of the U-phase signal, V-phase signal and W-phase signal by respectively performing digital conversion on the U-phase signal, V-phase signal and W-phase signal included in the three-phase signal; an abnormality determination process of determining an abnormal sensor, which is a magnetic sensor that is abnormal, among the three magnetic sensors by determining whether or not the instantaneous values Hu ', hv ' of the U-phase signal and Hw ' of the W-phase signal satisfy the equation (1) in all of the first case, the second case, and the third case; a signal generation process of generating a signal of the remaining one phase based on signals of two phases output from two magnetic sensors other than the abnormality sensor among the three magnetic sensors; and a position estimation process of estimating a rotational position of the motor based on the two-phase signals output from the two magnetic sensors other than the abnormality sensor and the generated remaining one-phase signal.
According to the present embodiment as described above, even when an abnormality occurs in one of the three magnetic sensors, the estimation of the rotational position of the motor can be continued by generating the signal of the remaining one phase based on the signals of the two phases output from the two magnetic sensors other than the abnormality sensor. Therefore, compared with the conventional technique of preparing circuits for detecting the rotation of the motors of the two systems, the miniaturization of the device and the reduction of the component cost can be realized.
When one of the two-phase signals output from the two magnetic sensors other than the anomaly sensor is a first signal and the other signal having a phase delay of 120 ° in electrical angle with respect to the first signal is a second signal, the signal processing unit of the present embodiment executes, in the signal generation process: a first process of obtaining an instantaneous value of the first signal and an instantaneous value of the second signal; a second process of calculating an instantaneous value of a synthesized signal of the first fundamental wave signal contained in the first signal and the second fundamental wave signal contained in the second signal by subtracting the instantaneous value of the second signal from the instantaneous value of the first signal; a third process of calculating a bias angle of the synthesized signal based on the instantaneous value of the synthesized signal and a norm of the synthesized signal prepared in advance; and a fourth process of calculating an instantaneous value of the third fundamental wave signal in a quadrature relationship with the synthesized signal based on the offset angle of the synthesized signal, the norm of the synthesized signal, and the phase difference between the synthesized signal and the first fundamental wave signal prepared in advance.
Thus, a signal (third fundamental wave signal) of a third phase not including the in-phase signal can be generated from the two-phase signals (first signal and second signal) obtained by the two magnetic sensors other than the anomaly sensor.
In the third processing, the signal processing unit according to the present embodiment calculates the offset angle ωt+Φ2 of the synthesized signal based on the expression (13), and performs expansion processing on the calculated offset angle ωt+Φ2, thereby obtaining the offset angle θ included in the range of-180 ° or more and less than 180 °.
Thus, the offset angle ωt+Φ2 of the synthesized signal can be calculated from the instantaneous value and the norm of the synthesized signal by a simple expression with a small processing load. In addition, when the offset angle ωt+Φ2 of the synthesized signal is calculated based on the expression (13), the offset angle ωt+Φ2 of the synthesized signal may be calculated by interpolation processing using table values. Further, by performing the expansion processing on the calculated offset angle ωt+Φ2 to obtain the offset angle θ included in the range of-180 ° or more and less than 180 °, the sine value of the offset angle θ can take on both positive polarity and negative polarity values in the range of-1 or more and 1 or less, and therefore the waveform of the third fundamental wave signal generated by the fourth processing can be made to be a complete sine waveform.
In the second processing, the signal processing unit of the present embodiment corrects at least one of the instantaneous value of the first signal and the instantaneous value of the second signal based on an amplitude correction value that equalizes the amplitude value of the first signal and the amplitude value of the second signal, which is prepared in advance, in the fourth process, the signal processing unit calculates an instantaneous value of the third fundamental wave signal by substituting the norm Huv, the phase difference Φ2, and the offset angle θ of the synthesized signal into equation (14).
Thus, by a simple equation with a small processing load, the instantaneous value of the third fundamental wave signal in a quadrature relationship with the synthesized signal can be calculated from the norm and the offset of the synthesized signal and the phase difference between the synthesized signal and the first fundamental wave signal.
The signal processing unit of the present embodiment further executes: fifth processing of calculating an instantaneous value of the in-phase signal based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third fundamental wave signal; a sixth process of calculating an instantaneous value of the first fundamental wave signal by subtracting an instantaneous value of the in-phase signal from an instantaneous value of the first signal; and seventh processing of calculating an instantaneous value of the second fundamental wave signal by subtracting the instantaneous value of the in-phase signal from the instantaneous value of the second signal.
Thus, the first fundamental wave signal having a sinusoidal waveform can be extracted from the first signal, and the second fundamental wave signal having a sinusoidal waveform and having a phase delay of 120 ° in electrical angle with respect to the first fundamental wave signal can be extracted from the second signal.
In the fifth processing, the signal processing unit according to the present embodiment calculates an instantaneous value of the in-phase signal based on the equation (15) and the equation (16).
Thus, the in-phase signal can be extracted from the first signal and the second signal by a simple expression with a small processing load.
The signal processing unit of the present embodiment cuts off the power supply to the abnormality sensors among the three magnetic sensors.
In this way, by cutting off the power supply to the abnormality sensor, the internal circuit of the position detection device can be protected.
(modification)
The present invention is not limited to the above embodiments, and the structures described in the present specification can be appropriately combined within a range not contradicting each other.
For example, in the above embodiment, the signal generation process in the case where the magnetic sensor 13 is an abnormal sensor has been described. That is, in the above embodiment, the signal generation process in the case where the U-phase signal Hu 'output from the magnetic sensor 11 is the first signal and the V-phase signal Hv' output from the magnetic sensor 12 is the second signal has been described. In contrast, when the magnetic sensor 11 is an anomaly sensor, the signal generation process can be performed with the V-phase signal Hv 'output from the magnetic sensor 12 as a first signal and the W-phase signal Hw' output from the magnetic sensor 13 as a second signal. In addition, when the magnetic sensor 12 is an anomaly sensor, the signal generation process can be performed using the W-phase signal Hw 'output from the magnetic sensor 13 as a first signal and the U-phase signal Hu' output from the magnetic sensor 11 as a second signal.
In the above embodiment, the case where the processing section 22 cuts off the power supply to the magnetic sensor 11 by switching the output voltage of the output port P1 to the low level is exemplified. In contrast, the following structure may be adopted: a buffer having a transistor is provided between the output port P1 and the magnetic sensor 11, and the buffer is controlled by the output voltage of the output port P1, thereby cutting off the power supply to the magnetic sensor 11. The same applies to the magnetic sensors 12 and 13.
For example, in the above embodiment, the combination of the motor and the position detecting device is exemplified, but the present invention is not limited to this embodiment, and may be a combination of a sensor magnet attached to a rotation shaft and a position detecting device.
In the above-described embodiment, the three magnetic sensors are disposed in a state of being opposed to the disk-shaped sensor magnet in the axial direction of the rotation shaft, but the present invention is not limited to this. For example, in the case of using a ring magnet instead of a disc-shaped sensor magnet, since the magnetic flux flows in the radial direction of the ring magnet, three magnetic sensors may be arranged so as to face the ring magnet in the radial direction of the ring magnet.
In the above embodiment, the case where the sensor magnet 120 attached to the rotor shaft 110 of the motor 100 is used as the rotating magnet is exemplified, but a rotor magnet attached to the rotor of the motor 100 may be used as the rotating magnet. The rotor magnets are also magnets that rotate in synchronization with the rotor shaft 110.
In the above embodiment, the case where the sensor magnet 120 has four pole pairs is exemplified, but the pole pair number of the sensor magnet 120 is not limited to four. In the case of using a rotor magnet as the rotary magnet, the pole pair number of the rotor magnet is not limited to four in the same way.
Symbol description
1-position detecting device, 11, 12, 13-magnetic sensor, 20-signal processing unit, 21-power circuit, 22-processing unit, 23-storage unit, 100-motor, 110-rotor shaft, 120-sensor magnet (magnet), 200-DC power supply.

Claims (14)

1. A position detection device for detecting a rotational position of a motor, the position detection device comprising:
three magnetic sensors that are disposed opposite to a magnet that rotates in synchronization with the motor and are arranged at predetermined intervals along a rotation direction of the magnet; and
a signal processing unit that processes three-phase signals having a phase difference of 120 DEG with respect to each other, which are output from the three magnetic sensors,
The signal processing section performs:
an acquisition process of acquiring an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal by respectively performing digital conversion on the U-phase signal, the V-phase signal, and the W-phase signal included in the three-phase signal;
an abnormality determination process of determining whether or not an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal satisfy the following expression (1) in all of the first case, the second case, and the third case, thereby determining an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors;
a signal generation process of generating a signal of the remaining one phase based on signals of two phases output from two magnetic sensors other than the abnormality sensor among the three magnetic sensors; and
a position estimating process of estimating a rotational position of the motor based on two-phase signals output from two magnetic sensors other than the abnormality sensor and the generated signal of the remaining one phase,
[ number 1]
(THmin-Hz’)＜(Hx’+Hy’)＜(THmax-Hz’)…(1)
Where the first case is x=u, y=v, z=w, the second case is x=v, y=w, z=v, the third case is x=w, y=u, z=v, THmin is a minimum threshold, and THmax is a maximum threshold.
2. The position detecting apparatus according to claim 1, wherein,
in the case where one of the two-phase signals output from the two magnetic sensors other than the abnormality sensor is set as a first signal and the other signal having a phase delay of 120 DEG electrical angle with respect to the first signal is set as a second signal,
the signal processing section performs, in the signal generation processing:
a first process of digitally converting the first signal and the second signal, thereby obtaining an instantaneous value of the first signal and an instantaneous value of the second signal;
a second process of subtracting an instantaneous value of the second signal from an instantaneous value of the first signal, thereby calculating an instantaneous value of a synthesized signal of the first fundamental wave signal contained in the first signal and the second fundamental wave signal contained in the second signal;
a third process of calculating a bias angle of the synthesized signal based on an instantaneous value of the synthesized signal and a norm of the synthesized signal prepared in advance; and
and a fourth process of calculating an instantaneous value of a third fundamental wave signal in a quadrature relationship with the synthesized signal as an instantaneous value of the signal of the remaining one phase, based on a bias angle of the synthesized signal, a norm of the synthesized signal, and a phase difference between the synthesized signal and the first fundamental wave signal prepared in advance.
3. The position detecting apparatus according to claim 2, wherein,
when the offset angle of the synthesized signal is ωt+Φ2, the instantaneous value of the synthesized signal is Huv, and the norm of the synthesized signal is Huv,
in the third processing, the signal processing unit calculates an offset angle ωt+Φ2 of the synthesized signal based on the following expression (13), and performs expansion processing on the calculated offset angle ωt+Φ2, thereby obtaining an offset angle θ included in a range of-180 DEG or more and less than 180 DEG,
[ number 2]
Wherein, -1 is less than or equal to (Huv/||) Huv is less than or equal to 1,
0≤(ωt+φ2)≤+180°。
4. a position detecting apparatus according to claim 3, wherein,
when the phase difference between the synthesized signal and the first fundamental wave signal is set to phi 2 and the instantaneous value of the third fundamental wave signal is set to Hw,
the signal processing unit corrects at least one of the instantaneous value of the first signal and the instantaneous value of the second signal based on an amplitude correction value which is prepared in advance and which makes the amplitude value of the first signal and the amplitude value of the second signal equal to each other in the second process,
the signal processing section substitutes the norm of the synthesized signal Huv, the phase difference phi 2, and the offset angle theta into the following equation (14) in the fourth process, thereby calculating an instantaneous value of the third fundamental wave signal,
[ number 3]
Wherein Φ2=yp.30° > 0 °.
5. The position detecting apparatus according to any one of claims 2 to 4, wherein,
the signal processing section further performs:
a fifth process of calculating an instantaneous value of an in-phase signal contained in the first signal and the second signal based on an instantaneous value of the first signal, an instantaneous value of the second signal, and an instantaneous value of the third fundamental wave signal;
a sixth process of subtracting an instantaneous value of the in-phase signal from an instantaneous value of the first signal, thereby calculating an instantaneous value of the first fundamental wave signal; and
seventh processing of subtracting the instantaneous value of the in-phase signal from the instantaneous value of the second signal, thereby calculating the instantaneous value of the second fundamental wave signal.
6. The position detecting apparatus according to claim 5, wherein,
when Hu 'is the instantaneous value of the first signal, hv' is the instantaneous value of the second signal, hw is the instantaneous value of the third fundamental wave signal, and N is the instantaneous value of the in-phase signal,
in the fifth process, the signal processing unit calculates an instantaneous value of the in-phase signal based on the following equations (15) and (16),
[ number 4]
Hw’＝-(Hu’+Hv’)…(15)
N＝-(Hw’-Hw)/2…(16)。
7. The position detecting apparatus according to any one of claims 1 to 6, wherein,
the signal processing unit cuts off power supply to the abnormality sensor among the three magnetic sensors.
8. A position detection method for detecting a rotational position of a motor using three-phase signals having a phase difference of 120 ° in electrical angle from each other, which are output from three magnetic sensors that face a magnet that rotates in synchronization with the motor and are arranged at predetermined intervals in a rotational direction of the magnet, the position detection method comprising:
an acquisition step of respectively performing digital conversion on a U-phase signal, a V-phase signal, and a W-phase signal included in the three-phase signal, thereby acquiring an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal;
an abnormality determining step of determining whether or not an instantaneous value Hu ' of the U-phase signal, an instantaneous value Hv ' of the V-phase signal, and an instantaneous value Hw ' of the W-phase signal satisfy the following expression (1) in all of a first case, a second case, and a third case, thereby determining an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors;
A signal generation step of generating a signal of the remaining one phase based on signals of two phases output from two magnetic sensors other than the abnormality sensor among the three magnetic sensors; and
a position estimating step of estimating a rotational position of the motor based on two-phase signals output from two magnetic sensors other than the abnormality sensor and the generated signal of the remaining one phase,
[ number 5]
(THmin-Hz’)＜(Hx’+Hy’)＜(THmax-Hz’)…(1)
Where the first case is x=u, y=v, z=w, the second case is x=v, y=w, z=v, the third case is x=w, y=u, z=v, THmin is a minimum threshold, and THmax is a maximum threshold.
9. The method for detecting a position according to claim 8, wherein,
in the case where one of the two-phase signals output from the two magnetic sensors other than the abnormality sensor is set as a first signal and the other signal having a phase delay of 120 DEG electrical angle with respect to the first signal is set as a second signal,
the signal generation step includes:
a first step of digitally converting the first signal and the second signal, thereby obtaining an instantaneous value of the first signal and an instantaneous value of the second signal;
A second step of subtracting an instantaneous value of the second signal from an instantaneous value of the first signal, thereby calculating an instantaneous value of a synthesized signal of the first fundamental wave signal contained in the first signal and the second fundamental wave signal contained in the second signal;
a third step of calculating a bias angle of the synthesized signal based on an instantaneous value of the synthesized signal and a norm of the synthesized signal prepared in advance; and
and a fourth step of calculating an instantaneous value of a third fundamental wave signal in an orthogonal relationship with the synthesized signal as an instantaneous value of the signal of the remaining one phase, based on a bias angle of the synthesized signal, a norm of the synthesized signal, and a phase difference between the synthesized signal and the first fundamental wave signal prepared in advance.
10. The method for detecting a position according to claim 9, wherein,
when the offset angle of the synthesized signal is ωt+Φ2, the instantaneous value of the synthesized signal is Huv, and the norm of the synthesized signal is Huv,
in the third step, the offset angle ωt+Φ2 of the synthesized signal is calculated based on the following formula (13), and the calculated offset angle ωt+Φ2 is subjected to expansion processing, thereby obtaining an offset angle θ included in a range of-180 ° or more and less than 180 °,
[ number 6]
Wherein, -1 is less than or equal to (Huv/||) Huv is less than or equal to 1,
0≤(ωt+φ2)≤+180°。
11. the method for detecting a position according to claim 10, wherein,
when the phase difference between the synthesized signal and the first fundamental wave signal is set to phi 2 and the instantaneous value of the third fundamental wave signal is set to Hw,
in the second step, at least one of the instantaneous value of the first signal and the instantaneous value of the second signal is corrected based on an amplitude correction value which is prepared in advance and which makes the amplitude value of the first signal and the amplitude value of the second signal equal,
in the fourth step, the norm of the synthesized signal Huv, the phase difference phi 2, and the offset angle theta are substituted into the following equation (14), thereby calculating an instantaneous value of the third fundamental wave signal,
[ number 7]
Wherein Φ2=yp.30° > 0 °.
12. The method for detecting a position according to any one of claims 9 to 11, wherein,
the signal generating step further includes:
a fifth step of calculating an instantaneous value of an in-phase signal contained in the first signal and the second signal based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third fundamental wave signal;
A sixth step of subtracting an instantaneous value of the in-phase signal from an instantaneous value of the first signal, thereby calculating an instantaneous value of the first fundamental wave signal; and
a seventh step of subtracting the instantaneous value of the in-phase signal from the instantaneous value of the second signal, thereby calculating the instantaneous value of the second fundamental wave signal.
13. The method of claim 12, wherein,
when Hu 'is the instantaneous value of the first signal, hv' is the instantaneous value of the second signal, hw is the instantaneous value of the third fundamental wave signal, and N is the instantaneous value of the in-phase signal,
in the fifth step, an instantaneous value of the in-phase signal is calculated based on the following expression (15) and the following expression (16),
[ number 8]
Hw’＝-(Hu’+Hv’)…(15)
N＝-(Hw’-Hw)/2…(16)。
14. The method for detecting a position according to any one of claims 8 to 13, wherein,
and a step of cutting off power supply to the abnormality sensor among the three magnetic sensors.
CN202180096395.8A 2021-03-30 2021-06-11 Position detection device and position detection method Pending CN117121363A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2021056376 2021-03-30
JP2021-056376 2021-03-30
PCT/JP2021/022352 WO2022208913A1 (en) 2021-03-30 2021-06-11 Position detection device and position detection method

Publications (1)

Publication Number Publication Date
CN117121363A true CN117121363A (en) 2023-11-24

Family

ID=83457576

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202180096395.8A Pending CN117121363A (en) 2021-03-30 2021-06-11 Position detection device and position detection method

Country Status (3)

Country Link
JP (1) JP7452757B2 (en)
CN (1) CN117121363A (en)
WO (1) WO2022208913A1 (en)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP5716954B2 (en) * 2011-01-17 2015-05-13 株式会社ジェイテクト Rotation angle detector
JP6166088B2 (en) 2013-03-29 2017-07-19 日立オートモティブシステムズ株式会社 Electromagnetic suspension device

Also Published As

Publication number Publication date
JP7452757B2 (en) 2024-03-19
WO2022208913A1 (en) 2022-10-06
JPWO2022208913A1 (en) 2022-10-06

Similar Documents

Publication Publication Date Title
US20120109562A1 (en) Rotational angle detection device
WO2019159311A1 (en) Control device for dc motor
CN108351197B (en) Angle detection device and electric power steering device
US9966884B2 (en) Method and device for determining the rotor position and speed of a rotating field machine
JP6844617B2 (en) Motor modules, motor step motion control systems, and motor controls
JP6205683B2 (en) Rotation angle detection device, image processing device, and rotation angle detection method
KR20090075757A (en) Motor driving apparatus
US11448526B2 (en) Position estimation method, position estimation device, and motor module for estimating position of rotor in motor
CN117121363A (en) Position detection device and position detection method
CN112146688B (en) Rotation angle detecting device
KR20110016573A (en) Rotor position sensor
JP6384199B2 (en) POSITION ESTIMATION DEVICE, MOTOR DRIVE CONTROL DEVICE, POSITION ESTIMATION METHOD, AND PROGRAM
JP7435904B2 (en) Three-phase signal generator and three-phase signal generation method
JP2014098642A (en) Angle correction device and rotation angle sensor
JP6619382B2 (en) Motor drive control device and control method of motor drive control device
JP5853641B2 (en) Line current detection device and power conversion system
WO2024004474A1 (en) Angle detection device and angle detection method
WO2022254863A1 (en) Angle detection method and angle detection device
WO2023167329A1 (en) Signal generation device and signal generation method
WO2023053598A1 (en) Three-phase signal generating device, and three-phase signal generating method
WO2023053596A1 (en) Three-phase signal generation device and three-phase signal generation method
WO2024004448A1 (en) Signal generation device and signal generation method
WO2023167328A1 (en) Signal generation device and signal generation method
US20240088808A1 (en) Position estimation method, position estimation device, unmanned transport vehicle, and sewing device
Wrobel et al. Design considerations for permanent magnet brushless machines for zero-speed sensorless position estimation

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination