JP2024145335A - Signal conversion method, position detection method, and position detection device - Google Patents

Abstract

To provide a signal converting method for converting a signal which can convert a plurality of analog signals to digital signals.SOLUTION: A signal converting method comprises: a first step of sequentially performing a plurality of times of sampling processing of sampling a value of an analog signal at least one time; and a second step, subsequently performed after the first step, of sequentially performing a plurality of times of sampling processing. The plurality of times of sampling processing which are performed in the first step includes at least one time of sampling processing on each of the analog signals. In the second step, the plurality of times of the sampling processing which are performed in the first step are performed in the opposite order to that of the first step.SELECTED DRAWING: Figure 4

Description

The present invention relates to a signal conversion method, a position detection method, and a position detection device.

Conventionally, a method is known in which multiple Hall sensors are used to detect the rotational position of a rotating body such as a motor rotor (for example, see Patent Document 1).

JP 2019-54656 A

In the above method, analog signals obtained from multiple Hall sensors are converted into digital signals, and the rotational position of the rotating body is detected based on the multiple digital signals obtained. In cases where an inexpensive device is used to convert analog signals into digital signals, multiple analog signals cannot be converted simultaneously, and analog signals may only be converted into digital signals one at a time. In such cases, in order to convert each of the multiple analog signals into a digital signal, the multiple analog signals must be converted into digital signals in sequence. Therefore, there is a problem in that the timing of acquiring the digital signal differs for each of the multiple analog signals, reducing the detection accuracy of the rotational position of the rotating body.

In view of the above circumstances, one of the objects of the present invention is to provide a signal conversion method capable of suppressing the occurrence of misalignment between multiple digital signals obtained by converting multiple analog signals, a position detection method using such a signal conversion method, and a position detection device capable of executing such a signal conversion method.

One aspect of the signal conversion method of the present invention is a signal conversion method for converting each of a plurality of analog signals into a digital signal, comprising a first step of sequentially performing a sampling process for sampling the value of the analog signal at least once a plurality of times, and a second step that follows the first step and sequentially performs the sampling process a plurality of times. The multiple sampling processes performed in the first step include the sampling process for each of the plurality of analog signals at least once. In the second step, the multiple sampling processes performed in the first step are performed in the reverse order to that of the first step.

One aspect of the position detection method of the present invention is a position detection method for detecting the rotational position of a rotating body, which includes acquiring a plurality of analog signals having different phases from each other by a plurality of rotation sensors capable of outputting analog signals according to the rotational position of the rotating body, and performing a detection step of detecting the rotational position of the rotating body based on the plurality of analog signals at a predetermined cycle. The detection step includes a conversion step of converting each of the plurality of analog signals into a digital signal by the above-mentioned signal conversion method, and a calculation step of calculating the rotational position of the rotating body based on the digital signal obtained in the conversion step.

One aspect of the position detection device of the present invention is a position detection device that detects the rotational position of a rotating body, comprising a plurality of rotation sensors capable of outputting analog signals that are analog signals corresponding to the rotational position of the rotating body and have different phases from each other, and a calculation unit capable of executing a detection step at a predetermined cycle to detect the rotational position of the rotating body based on the plurality of analog signals output from the plurality of rotation sensors. In the detection step, the calculation unit executes a conversion step of converting each of the plurality of analog signals into a digital signal, and a calculation step of calculating the rotational position of the rotating body based on the digital signal obtained in the conversion step. In the conversion step, the calculation unit executes a first step of sequentially performing a sampling process for sampling the value of the analog signal at least once or more multiple times, a second step that is performed following the first step and sequentially performs the sampling process multiple times, and a third step of calculating a value of a digital signal for each of the plurality of analog signals based on the sampling data obtained in the first step and the sampling data obtained in the second step. The multiple sampling processes performed in the first step include the sampling process for each of the plurality of analog signals at least once. In the second step, the calculation unit performs the sampling process multiple times in the reverse order to that performed in the first step.

According to one aspect of the present invention, it is possible to suppress the occurrence of discrepancies between multiple digital signals obtained by converting multiple analog signals.

FIG. 1 is a schematic diagram showing the configuration of a position detection device according to the first embodiment. FIG. 2 is a graph showing an example of a plurality of analog signals in the first embodiment. FIG. 3 is a flow chart showing the detection steps in the first embodiment. FIG. 4 is a diagram illustrating a detection step in the first embodiment. FIG. 5 is a diagram illustrating a first step and a second step in the first embodiment. FIG. 6 is a flow chart showing the detection steps in the second embodiment. FIG. 7 is a diagram illustrating another example of the first step and the second step. FIG. 8 is a diagram illustrating still another example of the first step and the second step. FIG. 9 is a diagram illustrating still another example of the first step and the second step.

First Embodiment
A position detection device 100 of this embodiment shown in Fig. 1 is a device that detects the rotational position of a rotor 20 of a motor 10. In this embodiment, the motor 10 is a three-phase motor. The rotor 20 is a rotating body that can rotate around a central axis J. In the following description, the axial direction in which the central axis J extends may be simply referred to as the "axial direction," and the circumferential direction around the central axis J may be simply referred to as the "circumferential direction."

As shown in FIG. 1, the rotor 20 is provided with a magnet 30. The magnet 30 is, for example, annular and surrounds the central axis J. The magnet 30 has magnetic pole portions 30N and 30S arranged alternately in the circumferential direction around the central axis J. The magnetic pole portion 30N is a north pole. The magnetic pole portion 30S is a south pole. Four magnetic pole portions 30N and 30S are provided. That is, in this embodiment, the magnet 30 has four pole pairs. The pole pair means a pair of a north pole and a south pole. The magnet 30 may be a rotor magnet in which the magnetic flux of the magnet 30 flows between the rotor 20 and a stator (not shown) in the motor 10, or may be a sensor magnet provided on the rotor 20 separately from the rotor magnet.

The position detection device 100 includes a magnet 30, multiple rotation sensors 40, and a signal processing device 50. Although not shown, the position detection device 100 also includes a circuit board that faces the magnet 30 in the axial direction. The multiple rotation sensors 40 and the signal processing device 50 are attached to the circuit board, for example.

The multiple rotation sensors 40 can output an analog signal HS corresponding to the rotation position of the rotor 20, which is a rotating body. The analog signals HS output from the multiple rotation sensors 40 have different phases from each other. In this embodiment, the multiple rotation sensors 40 are magnetic sensors that can detect the magnetic field of the magnet 30. Therefore, while the rotation sensors 40 are inexpensive sensors, the rotation position of the rotor 20, which is a rotating body, can be easily detected by detecting the magnetic field of the magnet 30 using the rotation sensors 40.

The rotation sensor 40 outputs an analog signal HS that indicates the magnetic field strength that changes depending on the rotational position of the rotor 20, i.e., the rotational position of the magnet 30. The type of the magnetic sensor, the rotation sensor 40, is not particularly limited as long as it is a magnetic sensor that can output the analog signal HS. The rotation sensor 40 may be a Hall element, a linear Hall IC, or a magnetic resistance element. In this embodiment, three rotation sensors 40 are provided: a first rotation sensor 41, a second rotation sensor 42, and a third rotation sensor 43.

The first rotation sensor 41, the second rotation sensor 42, and the third rotation sensor 43 are arranged at a predetermined interval in the circumferential direction. In this embodiment, the first rotation sensor 41, the second rotation sensor 42, and the third rotation sensor 43 are arranged in this order at intervals of 30° in the circumferential direction. If the number of pole pairs of the magnet 30 is P, one electrical angle period of each analog signal HS output from each rotation sensor 40 corresponds to 1/P of one mechanical angle period. In this embodiment, since the number of pole pairs P of the magnet 30 is "4", one electrical angle period of each analog signal HS output from each rotation sensor 40 corresponds to 1/4 of one mechanical angle period, that is, 90° in mechanical angle. In this embodiment, the analog signals HS output from adjacent rotation sensors 40 in the circumferential direction have a phase difference of 120° in electrical angle.

The analog signal HS output from the first rotation sensor 41 is the first analog signal Hu. The analog signal HS output from the second rotation sensor 42 is the second analog signal Hv. The analog signal HS output from the third rotation sensor 43 is the third analog signal Hw. As shown in FIG. 2, the first analog signal Hu, the second analog signal Hv, and the third analog signal Hw are sine waves. In FIG. 2, the horizontal axis is the rotation angle θ of the rotor 20, and the vertical axis is the voltage V. The rotation angle θ is a mechanical angle. When the rotor 20 rotates at a constant rotation speed, each analog signal HS changes in the same manner as the graph shown in FIG. 2 with the horizontal axis being time. In this embodiment, the second analog signal Hv has a phase delay of 120° in electrical angle with respect to the first analog signal Hu. The third analog signal Hw has a phase delay of 120° in electrical angle with respect to the second analog signal Hv. As shown in FIG. 1, the first analog signal Hu, the second analog signal Hv, and the third analog signal Hw are input to the signal processing device 50.

The signal processing device 50 is a device that processes multiple analog signals HS output from multiple rotation sensors 40. In this embodiment, the signal processing device 50 calculates the rotation angle θ of the rotor 20, which is a rotating body, based on the first analog signal Hu, the second analog signal Hv, and the third analog signal Hw. The signal processing device 50 has a calculation unit 51 and a memory unit 52. In other words, the position detection device 100 has a calculation unit 51 and a memory unit 52.

The calculation unit 51 is a part that calculates the rotation angle θ of the rotor 20, which is a rotating body, based on the first analog signal Hu, the second analog signal Hv, and the third analog signal Hw. The calculation unit 51 is, for example, a microprocessor such as an MCU (Microcontroller Unit). The calculation unit 51 is connected to the storage unit 52 so as to be able to communicate data with it, for example, via a data bus. The calculation unit 51 receives the first analog signal Hu, the second analog signal Hv, and the third analog signal Hw. The calculation unit 51 is capable of executing a detection step Sd1 at a predetermined period ts, which detects the rotation position of the rotor 20, which is a rotating body, based on the multiple analog signals HS output from the multiple rotation sensors 40.

The storage unit 52 includes a non-volatile memory that stores programs, various values, learning data, and the like required for the calculation unit 51 to execute various processes, and a volatile memory that is used as a temporary storage destination for data when the calculation unit 51 executes various processes. The non-volatile memory is, for example, an EEPROM (Electrically Erasable Programmable Read-Only Memory) or a flash memory. The volatile memory is, for example, a RAM (Random Access Memory).

In this embodiment, the position detection device 100 obtains a first analog signal Hu, a second analog signal Hv, and a third analog signal Hw as a plurality of analog signals HS by a plurality of rotation sensors 40, and detects the rotational position of the rotor 20, which is a rotating body, as a rotation angle θ at a predetermined period ts by performing a detection step Sd1 at a predetermined period ts using the plurality of analog signals HS obtained by the calculation unit 51. In this embodiment, a position detection method for detecting the rotational position of the rotor 20, which is a rotating body, is a method performed using the position detection device 100. The position detection method of this embodiment includes obtaining a plurality of analog signals HS having different phases from each other by a plurality of rotation sensors 40 capable of outputting an analog signal HS according to the rotational position of the rotor 20, and performing a detection step Sd1 at a predetermined period ts to detect the rotational position of the rotor 20 based on the plurality of analog signals HS. As an example, the period ts is about 5 microseconds (μs) or more and 100 microseconds (μs) or less.

In this embodiment, the calculation unit 51 executes the detection step Sd1 in accordance with the flowchart of FIG. 3. As shown in FIG. 3, in the detection step Sd1, the calculation unit 51 executes the conversion step Scv. That is, the detection step Sd1 includes the conversion step Scv. The conversion step Scv is a step of converting each of the multiple analog signals HS into a digital signal by the signal conversion method of this embodiment. In other words, the conversion step Scv is a step of performing A/D conversion.

In this embodiment, the calculation unit 51 can only convert analog signals HS into digital signals one at a time. Therefore, the microprocessor constituting the calculation unit 51 can be made cheaper than when the calculation unit 51 is provided with the ability to convert multiple analog signals HS into digital signals simultaneously. This reduces the manufacturing cost of the position detection device 100. The sampling rate of the A/D conversion that the calculation unit 51 can perform may be, for example, about several hundred k samples/second (sps) or about several thousand k samples/second (sps). The sampling rate of the A/D conversion that the calculation unit 51 can perform is, for example, about 100 k samples/second (sps) or more and 10,000 k samples/second (sps) or less. The sampling rate of the A/D conversion that the calculation unit 51 can perform is not particularly limited.

In the conversion step Scv, the calculation unit 51 executes a first step S1a, a second step S2a, and a third step S3a. That is, the conversion step Scv includes a first step S1a, a second step S2a, and a third step S3a. The first step S1a, the second step S2a, and the third step S3a are executed in this order.

The first step S1a is a step of sequentially performing the sampling process Sp multiple times. The sampling process Sp is a process of sampling the value of the analog signal HS at least once. For example, the sampling process Sp samples the value of the analog signal HS eight times. The number of samplings performed in the sampling process Sp is not particularly limited as long as it is one or more times. As shown in FIG. 4, in the first step S1a of this embodiment, the sampling process Sp is performed three times. In the sampling process Sp of this embodiment, the calculation unit 51 acquires, as the sampling data, a total value obtained by adding up the values obtained by sampling the analog signal HS multiple times. In FIG. 4, the horizontal axis represents time t.

The multiple sampling processes Sp performed in the first step S1a include at least one sampling process Sp for each of the multiple analog signals HS output from the multiple rotation sensors 40. In this embodiment, the multiple sampling processes Sp performed in the first step S1a include the same number of sampling processes Sp for each of the multiple analog signals HS output from the multiple rotation sensors 40. The multiple sampling processes Sp performed in the first step S1a include one each of the first sampling process Us performed on the first analog signal Hu, the second sampling process Vs performed on the second analog signal Hv, and the third sampling process Ws performed on the third analog signal Hw. In the first step S1a of this embodiment, the first sampling process Us, the second sampling process Vs, and the third sampling process Ws are performed consecutively in this order.

The second step S2a is performed following the first step S1a, and is a step in which the sampling process Sp is performed multiple times in sequence. In the second step S2a of this embodiment, the sampling process Sp is performed three times. The multiple sampling processes Sp performed in the second step S2a include at least one sampling process Sp for each of the multiple analog signals HS output from the multiple rotation sensors 40. In this embodiment, the multiple sampling processes Sp performed in the second step S2a include the same number of sampling processes Sp for each of the multiple analog signals HS output from the multiple rotation sensors 40. In this embodiment, the multiple sampling processes Sp performed in the second step S2a include one each of the first sampling process Us performed on the first analog signal Hu, the second sampling process Vs performed on the second analog signal Hv, and the third sampling process Ws performed on the third analog signal Hw. In other words, the multiple sampling processes Sp performed in the second step S2a are the same as the multiple sampling processes Sp performed in the first step S1a.

The multiple sampling processes Sp performed in the second step S2a are performed in a different order from the multiple sampling processes Sp performed in the first step S1a. In the second step S2a of this embodiment, the third sampling process Ws, the second sampling process Vs, and the first sampling process Us are executed consecutively in this order. That is, in the second step S2a, the calculation unit 51 performs the multiple sampling processes Sp performed in the first step S1a in the reverse order to the first step S1a.

The sampling data obtained in the first step S1a sampling process Sp and the second step S2a sampling process Sp can be regarded as values obtained at the central time between the start and end of each sampling process Sp in a relative comparison of each sampling data. This is because, as shown in FIG. 5, within the sufficiently short time in which each detection step Sd1 is executed, the change in each analog signal HS with respect to time t can be linearly approximated. In the upper and lower graphs in FIG. 5, the horizontal axis is time t. In the upper graph in FIG. 5, the vertical axis is voltage V. In the following description, the central time between the start and end of each sampling process Sp may be referred to as the central time of each sampling process Sp.

For example, if the first analog signal Hu can be approximated as a signal that changes linearly over time, and multiple samplings are performed at regular intervals in the first sampling process Us, the value of the first analog signal Hu at the center time of the first sampling process Us can be considered to be equivalent to the average value obtained by adding up all the values obtained from the multiple samplings and dividing the sum by the number of samplings performed in the first sampling process Us. The same is true for the second sampling process Vs and the third sampling process Ws.

Here, the number of samplings performed in the first sampling process Us, the number of samplings performed in the second sampling process Vs, and the number of samplings performed in the third sampling process Ws are the same. Therefore, the ratio between the values obtained by summing up the data obtained by multiple samplings in each sampling process Sp is the same as the ratio between the values obtained from each analog signal HS at the center time of each sampling process Sp. Therefore, as in this embodiment, in each sampling process Sp, the sum of the values obtained by multiple samplings is obtained as sampling data, and when comparing the sampling data between each analog signal HS, each sampling data can be treated as a value obtained at the center time of each sampling process Sp.

In FIG. 5, the value of the first analog signal Hu at the center time of the first sampling process Us in the first step S1a is indicated by PU1. The value of the second analog signal Hv at the center time of the second sampling process Vs in the first step S1a is indicated by PV1. The value of the third analog signal Hw at the center time of the third sampling process Ws in the first step S1a is indicated by PW1. The value of the first analog signal Hu at the center time of the first sampling process Us in the second step S2a is indicated by PU2. The value of the second analog signal Hv at the center time of the second sampling process Vs in the second step S2a is indicated by PV2. The value of the third analog signal Hw at the center time of the third sampling process Ws in the second step S2a is indicated by PW2. In this embodiment, the ratio between the values PU1, PV1, PW1, PU2, PV2, and PW2 can be considered to be equivalent to the ratio between the total values of each sampling data obtained in each sampling process Sp, that is, the sum of the values obtained by multiple sampling in each sampling process Sp.

The third step S3a is a step of calculating the value of a digital signal based on the sampling data obtained in the first step S1a and the sampling data obtained in the second step S2a for each of the multiple analog signals HS. In the third step S3a of this embodiment, the calculation unit 51 adds up the sampling data obtained in the first step S1a and the sampling data obtained in the second step S2a for each of the multiple analog signals HS. In other words, in this embodiment, the third step S3a includes adding up the sampling data obtained in the first step S1a and the sampling data obtained in the second step S2a for each of the multiple analog signals HS.

In the third step S3a, the calculation unit 51 calculates the sum of the sampling data obtained from the first analog signal Hu in the first sampling process Us in the first step S1a and the sampling data obtained from the first analog signal Hu in the first sampling process Us in the second step S2a as the value of the digital signal converted from the first analog signal Hu.

In the third step S3a, the calculation unit 51 calculates the sum of the sampling data obtained from the second analog signal Hv in the second sampling process Vs in the first step S1a and the sampling data obtained from the second analog signal Hv in the second sampling process Vs in the second step S2a as the value of the digital signal converted from the second analog signal Hv.

In the third step S3a, the calculation unit 51 calculates the sum of the sampling data obtained from the third analog signal Hw in the third sampling process Ws in the first step S1a and the sampling data obtained from the third analog signal Hw in the third sampling process Ws in the second step S2a as the value of the digital signal converted from the third analog signal Hw.

The value of each digital signal obtained in the third step S3a can be regarded as the value obtained at the timing Ta at which the first step S1a and the second step S2a switch in a relative comparison of the values of the digital signals obtained from each analog signal HS. This is because, as described above, within the sufficiently short time in which each detection step Sd1 is executed, the change in each analog signal HS with respect to time t can be linearly approximated, and in the sampling process Sp for any analog signal HS, the center time from the start of the first sampling process Sp to the end of the last sampling process Sp in the detection step Sd1 is the timing Ta.

Specifically, the center time between the start of the first sampling process Us in the detection step Sd1 and the end of the last sampling process Us, the center time between the start of the first sampling process Vs in the detection step Sd1 and the end of the last sampling process Vs, and the center time between the start of the first sampling process Ws in the detection step Sd1 and the end of the last sampling process Ws are the same and are the timing Ta. The timing Ta at which the first step S1a and the second step S2a switch is the time when the first step S1a ends and the time when the second step S2a starts.

5, for example, in the case where the first analog signal Hu can be approximated to a signal that changes linearly with time, the value PU of the first analog signal Hu at the timing Ta can be regarded as a value equivalent to the average value obtained by adding the value PU1 of the first analog signal Hu at the center time of the first sampling process Us of the first step S1a and the value PU2 of the first analog signal Hu at the center time of the first sampling process Us of the second step S2a and dividing the sum by the total number of times the first sampling process Us is performed in the first step S1a and the second step S2a. In other words, in this embodiment, the value PU of the first analog signal Hu at the timing Ta can be regarded as a value equivalent to the value obtained by dividing the sum of the value PU1 of the first analog signal Hu and the value PU2 of the first analog signal Hu by 2. This also applies to the second analog signal Hv and the third analog signal Hw. In other words, the value PV of the second analog signal Hv at the timing Ta can be considered to be a value equivalent to the sum of the value PV1 of the second analog signal Hv and the value PV2 of the second analog signal Hv, divided by 2. The value PW of the third analog signal Hw at the timing Ta can be considered to be a value equivalent to the sum of the value PW1 of the third analog signal Hw and the value PW2 of the third analog signal Hw, divided by 2.

As described above, the ratio between the values PU1, PV1, PW1, PU2, PV2, and PW2 can be regarded as being equivalent to the ratio between the sampling data obtained in each sampling process Sp, so that in a relative comparison between multiple analog signals HS, the values PU1, PV1, PW1, PU2, PV2, and PW2 can be replaced with the sampling data obtained in each sampling process Sp. Therefore, the value of the digital signal calculated by adding up the sampling data obtained in the first sampling process Us in the first step S1a and the second step S2a divided by the total number of times the first sampling process Us is performed in the first step S1a and the second step S2a can be regarded as the sampling data of the first analog signal Hu obtained at timing Ta.

The value of the digital signal calculated by adding up the sampling data obtained in the second sampling process Vs in the first step S1a and the second step S2a and dividing the value by the total number of times the second sampling process Vs is performed in the first step S1a and the second step S2a can be regarded as the sampling data of the second analog signal Hv obtained at the timing Ta.

The value of the digital signal calculated by adding up the sampling data obtained in the third sampling process Ws in the first step S1a and the second step S2a and dividing the value by the total number of times the third sampling process Ws is performed in the first step S1a and the second step S2a can be regarded as the sampling data of the third analog signal Hw obtained at the timing Ta.

Here, the total number of the first sampling process Us, the total number of the second sampling process Vs, and the total number of the third sampling process Ws performed in the first step S1a and the second step S2a are all two, which is the same as each other. Therefore, in a relative comparison between the digital signals corresponding to the multiple analog signals HS, the value of each digital signal calculated in the third step S3a by adding up the sampling data in the sampling process Sp for each of the multiple analog signals HS can be treated as the value of the digital signal corresponding to each analog signal HS at the timing Ta.

As described above, according to this embodiment, the multiple sampling processes Sp performed in the first step S1a include at least one sampling process Sp for each of the multiple analog signals HS, and in the second step S2a, the multiple sampling processes Sp performed in the first step S1a are performed in the reverse order to the first step S1a. Therefore, for each of the multiple analog signals HS, the number of sampling processes Sp performed in the first step S1a and the number of sampling processes Sp performed in the second step S2a can be made the same, and for each analog signal HS, the center time from the start of the first sampling process Sp to the end of the last sampling process Sp can be set to the timing Ta at which the first step S1a and the second step S2a switch. As a result, it is possible to obtain the value of the digital signal obtained by converting each analog signal HS as a value equivalent to the value obtained simultaneously at the same timing Ta. Therefore, even if the calculation unit 51 can only convert one analog signal HS at a time, it is possible to prevent deviations from occurring between multiple digital signals obtained by converting multiple analog signals HS.

In this embodiment, the conversion step Scv includes a third step S3a in which a digital signal value is calculated for each of the multiple analog signals HS based on the sampling data obtained in the first step S1a and the sampling data obtained in the second step S2a. Therefore, in the third step S3a, a digital signal value corresponding to the digital signal obtained at the same time can be obtained for each of the multiple analog signals HS.

In this embodiment, the third step S3a includes adding up the sampling data obtained in the first step S1a and the sampling data obtained in the second step S2a for each of the multiple analog signals HS. Therefore, for example, as described above, it is easy to obtain the value of the digital signal corresponding to the digital signal obtained at the timing Ta. In particular, in this embodiment, the multiple sampling processes Sp performed in the first step S1a include the same number of sampling processes Sp for each of the multiple analog signals HS. Therefore, as described above, the value obtained by adding up the sampling data obtained in the first step S1a and the sampling data obtained in the second step S2a can be treated as a value corresponding to the value of the digital signal obtained at the timing Ta. This makes it easier to obtain the value of the digital signal corresponding to the digital signal obtained at the timing Ta for each of the multiple analog signals HS.

As shown in FIG. 3, in the detection step Sd1 of this embodiment, the calculation unit 51 determines whether the current detection step Sd1 is the second or subsequent detection step Sd1 after the conversion step Scv (step Sj1). If the current detection step Sd1 is the first detection step Sd1 (step Sj1: NO), the calculation unit 51 executes the calculation step Sca1 to calculate the rotational position of the rotor 20, which is a rotating body, based on the digital signal obtained in the conversion step Scv. In other words, the detection step Sd1 includes the calculation step Sca1. In this embodiment, the first detection step Sd1 is the detection step Sd1 that is executed first by the calculation unit 51 after the power supply to the calculation unit 51, which had been stopped, begins to be supplied with power.

If the current detection step Sd1 is the first detection step Sd1, in the calculation step Sca1, the calculation unit 51 calculates the rotational position of the rotor 20, i.e., the rotation angle θ, using the value of the digital signal obtained in the conversion step Scv without correction. The method by which the calculation unit 51 calculates the rotation angle θ from the value of the digital signal is not particularly limited. For example, the calculation unit 51 can calculate the rotation angle θ using the method described in Japanese Patent No. 6233532. In this embodiment, as described above, it is possible to suppress the occurrence of deviations between the multiple digital signals obtained by converting the multiple analog signals HS, and therefore it is possible to improve the accuracy of the rotation angle θ calculated based on the values of the multiple digital signals.

If the current detection step Sd1 is the second or later detection step Sd1 (step Sj1: YES), the calculation unit 51 executes a correction step Scr1 to correct the value of the digital signal obtained in the conversion step Scv. In the correction step Scr1, the calculation unit 51 calculates an estimate value De of the digital signal obtained based on the value of the analog signal HS after the first predetermined time tpa from the timing Ta based on the value of the digital signal obtained in the third step S3a and the value of the digital signal obtained in the third step S3a of the detection step Sd1 performed one time before. In other words, the detection step Sd1 performed from the second time onwards includes calculating an estimate value De of the digital signal obtained based on the value of the analog signal HS after the first predetermined time tpa from the timing Ta at which the first step S1a and the second step S2a switch, based on the value of the digital signal obtained in the third step S3a and the value of the digital signal obtained in the third step S3a of the detection step Sd1 performed one time before. Therefore, it is possible to obtain a value of the digital signal equivalent to the case where it is obtained at a timing different from the timing Ta. This makes it possible to detect the rotational position of the rotor 20, which is a rotating body, based on the value of the digital signal at any given time.

As shown in FIG. 4, in this embodiment, the first predetermined time tpa is equal to the time from the timing Ta at which the first step S1a and the second step S2a switch to the calculation of the rotational position of the rotor 20, which is a rotating body, in the calculation step Sca1. Therefore, the value of the estimated value De can be set to a value equivalent to the value of the digital signal acquired at the timing at which the rotation angle θ is calculated. As a result, even if the timing Ta and the timing Tb at which the rotation angle θ is calculated differ as in this embodiment, it is possible to output a value equivalent to the rotation angle θ at the timing Tb using the estimated value De equivalent to the digital signal acquired at the timing Tb. Therefore, it is possible to suppress the occurrence of a time lag in the value of the rotation angle θ output from the position detection device 100. Therefore, the detection accuracy of the position detection device 100 can be further improved. Note that the first predetermined time tpa is not particularly limited.

In this embodiment, timing Tb is the time when the rotation angle θ is calculated and is also the timing when calculation step Sca1 ends. That is, in this embodiment, the first predetermined time tpa is equal to the time from timing Ta to the end of calculation step Sca1. In this embodiment, the first predetermined time tpa is equal to the sum of the time to execute the second step S2a, the time to execute the third step S3a, the time to execute correction step Scr1, and the time to execute calculation step Sca1. The first predetermined time tpa is, for example, about several tens of microseconds (μs). The first predetermined time tpa is, for example, about 1 microsecond (μs) or more and 100 microseconds (μs) or less.

In FIG. 4, the number of detection steps Sd1 is indicated by using an integer M of 2 or more. Specifically, detection step Sd1[M] is the Mth detection step Sd1. Timing Ta[M] is the timing Ta in the Mth detection step Sd1. FIG. 4 illustrates an example where M=2. That is, detection step Sd1[M-1] shown in FIG. 4 is the first detection step Sd1. In correction step Scr1 in detection steps Sd1 performed from the second time onwards, calculation unit 51 calculates an estimate De of the digital signal using the following formula (1).

De=D[M]+(D[M]-D[M-1])/ts×tpa...Formula (1)

In formula (1), D[M] is the value of the digital signal obtained in the third step S3a of the Mth detection step Sd1. D[M-1] is the value of the digital signal obtained in the third step S3a of the (M-1)th detection step Sd1. ts is a predetermined period ts. tpa is a first predetermined time tpa. In correction step Scr1, the calculation unit 51 corrects the value of each digital signal obtained from each of the multiple analog signals HS to an estimated value De using the above formula (1).

In formula (1), (D[M]-D[M-1])/ts is the rate of change per unit time of the value when the analog signal HS that can be linearly approximated within the period including the previous detection step Sd1 and the current detection step Sd1 is converted into a digital signal. By multiplying this rate of change by the first predetermined time tpa, the value of the digital signal that changes from timing Ta in the Mth detection step Sd1 until the first predetermined time tpa later can be calculated. By adding this value to the value D[M] of the digital signal obtained in the third step S3a in the Mth detection step Sd1, it is possible to preferably calculate an estimated value De equivalent to the value of the digital signal from timing Ta until the first predetermined time tpa later. In this embodiment, as described above, it is possible to preferably calculate a value equivalent to the value of the digital signal obtained at timing Tb when the rotation angle θ is calculated, and it is possible to more preferably obtain the rotation angle θ with high accuracy.

As shown in FIG. 3, after performing the correction step Scr1, the calculation unit 51 calculates the rotational position of the rotor 20, i.e., the rotational angle θ, using the estimated value De, which is the corrected digital value (calculation step Sca1). The method by which the calculation unit 51 calculates the rotational angle θ from the estimated value De in the second and subsequent detection steps Sd1 is the same as the method by which the calculation unit 51 calculates the rotational angle θ in the first detection step Sd1.

Below, an embodiment different from the above-mentioned embodiment will be described. In the following description of each embodiment, the description of the same configuration as that described above in the description of each embodiment may be omitted by appropriately assigning the same reference numerals. In addition, the parts corresponding to the respective parts of the configuration described above in the description of each embodiment may be assigned the same names but different reference numerals to describe the differences from the above-mentioned configuration, and the description of the similarities to the above-mentioned configuration may be omitted. Note that, as the configuration whose description is omitted in each of the following embodiments, the same configuration as that described above in the description of each embodiment may be adopted within the scope of not being inconsistent.

Second Embodiment
In this embodiment, the calculation unit 51 executes the detection step Sd2 in accordance with the flowchart of Fig. 6. In the detection step Sd2, the calculation unit 51 executes the conversion step Scv in the same manner as the detection step Sd1 in the first embodiment. After executing the conversion step Scv, the calculation unit 51 executes the calculation step Sca2 in which the rotational position of the rotor 20, i.e., the rotation angle θ, is calculated based on the value of the digital signal obtained in the conversion step Scv. The calculation step Sca2 is similar to the calculation step Sca1 in the first embodiment, except that it is performed immediately after the conversion step Scv.

In the detection step Sd2 of this embodiment, the calculation unit 51 determines after the calculation step Sca2 whether the current detection step Sd2 is the second or subsequent detection step Sd2 (step Sj2). If the current detection step Sd2 is the first detection step Sd2 (step Sj2: NO), the calculation unit 51 outputs the rotation angle θ obtained in the calculation step Sca2 without correcting it. In this embodiment, the first detection step Sd2 is the detection step Sd2 that is first executed by the calculation unit 51 after the power supply to the calculation unit 51, which had been stopped, begins to be supplied with power.

If the current detection step Sd2 is the second or later detection step Sd2 (step Sj2: YES), the calculation unit 51 executes a correction step Scr2 to correct the rotational position of the rotor 20 obtained in the calculation step Sca2, i.e., the value of the rotational angle θ. In the correction step Scr2 of the second or later detection step Sd2, the calculation unit 51 calculates an estimated value θe of the rotational angle θ after the second predetermined time tpb based on the rotational angle θ obtained in the calculation step Sca2 and the rotational angle θ obtained in the calculation step Sca2 of the detection step Sd2 performed one time before. In other words, the detection step Sd2 performed from the second time onwards includes calculating an estimated value θe of the rotational position of the rotor 20 after the second predetermined time tpb based on the rotational position of the rotor 20, which is a rotating body, obtained in the calculation step Sca2 and the rotational position of the rotor 20 obtained in the calculation step Sca2 of the detection step Sd2 performed one time before. Therefore, it is possible to detect the rotational position of the rotor 20 corresponding to the digital signal value acquired at a timing different from the timing Ta. This makes it possible to detect the rotational position of the rotor 20 at any timing.

In the correction step Scr2 of the detection step Sd2 performed for the second or subsequent times, the calculation unit 51 calculates the estimated value De of the digital signal using the following formula (2).

θe=θ[M]+(θ[M]-θ[M-1])/ts×tpb...Formula (2)

In equation (1), θ[M] is the value of rotation angle θ obtained in calculation step Sca2 of the Mth detection step Sd2. θ[M-1] is the value of rotation angle θ obtained in calculation step Sca2 of the (M-1)th detection step Sd2. ts is a predetermined period ts. tpb is a second predetermined time tpb. In correction step Scr2, the calculation unit 51 corrects the value of rotation angle θ obtained in calculation step Sca2 to an estimated value θe using the above equation (2).

In formula (2), (θ[M] - θ[M-1])/ts is the rate of change per unit time of the rotation angle θ that can be linearly approximated within the period including the previous detection step Sd2 and the current detection step Sd2. By multiplying this rate of change by the second predetermined time tpb, it is possible to calculate the value of the rotation angle θ that changes from timing Ta in the Mth detection step Sd2 until the second predetermined time tpb later. By adding this value to the value θ[M] of the rotation angle θ obtained in the calculation step Sca2 in the Mth detection step Sd2, it is possible to suitably calculate an estimated value θe that corresponds to the value of the rotation angle θ from timing Ta until the second predetermined time tpb later.

In this embodiment, the second predetermined time tpb is equal to the time from the timing Ta at which the first step S1a and the second step S2a switch to the time at which the estimated value θe is calculated. Therefore, the rotation angle θ corresponding to the case where multiple analog signals HS are sampled at the timing at which the estimated value θe is calculated can be calculated as the estimated value θe. Therefore, it is possible to suppress the occurrence of a time lag in the output rotation angle θ, and it is possible to obtain the rotation angle θ with more suitable accuracy. Note that the second predetermined time tpb is not particularly limited. The second predetermined time tpb is, for example, about several tens of microseconds (μs). The second predetermined time tpb is, for example, about 1 microsecond (μs) or more and 100 microseconds (μs) or less.

The present invention is not limited to the above-described embodiment, and other configurations and methods may be adopted within the scope of the technical concept of the present invention. The multiple sampling processes performed in the first step may be performed in any order and may include any number of sampling processes for each analog signal, so long as the multiple sampling processes performed in the first step include at least one sampling process for each analog signal. The second step may be performed in any order and may include any number of sampling processes for each analog signal, so long as the multiple sampling processes similar to those performed in the first step are performed in the reverse order to the first step.

The first step and the second step may be configured as, for example, the first step S1b and the second step S2b shown in FIG. 7. As shown in FIG. 7, the multiple sampling processes Sp performed in the first step S1b and the multiple sampling processes Sp performed in the second step S2b each include one first sampling process Us performed on the first analog signal Hu, one second sampling process Vs performed on the second analog signal Hv, and one third sampling process Ws performed on the third analog signal Hw. In the first step S1b, the second sampling process Vs, the third sampling process Ws, and the first sampling process Us are performed consecutively in this order. In the second step S2b, the first sampling process Us, the third sampling process Ws, and the second sampling process Vs are performed consecutively in this order.

The first step and the second step may be configured as, for example, the first step S1c and the second step S2c shown in FIG. 8. As shown in FIG. 8, the multiple sampling processes Sp performed in the first step S1c and the multiple sampling processes Sp performed in the second step S2c each include the first sampling process Us performed on the first analog signal Hu, the second sampling process Vs performed on the second analog signal Hv, and the third sampling process Ws performed on the third analog signal Hw, two times each. That is, the first step S1c and the second step S2c each include six sampling processes Sp. In the first step S1c, the first sampling process Us, the third sampling process Ws, the second sampling process Vs, the third sampling process Ws, the second sampling process Vs, and the first sampling process Us are executed in this order in succession. In the second step S2c, the first sampling process Us, the second sampling process Vs, the third sampling process Ws, the second sampling process Vs, the third sampling process Ws, and the first sampling process Us are executed consecutively in this order.

The first step and the second step may be configured, for example, as the first step S1d and the second step S2d shown in FIG. 9. As shown in FIG. 9, the multiple sampling processes Sp performed in the first step S1d and the multiple sampling processes Sp performed in the second step S2c each include one first sampling process Us, two second sampling processes Vs, and three third sampling processes Ws. That is, in the example of FIG. 9, the multiple sampling processes Sp performed in the first step S1d and the second step S2d include different numbers of sampling processes Sp for each of the multiple analog signals HS.

The total number of times the first sampling process Us is performed in the first step S1d and the second step S2d is two. The total number of times the second sampling process Vs is performed in the first step S1d and the second step S2d is four. The total number of times the third sampling process Ws is performed in the first step S1d and the second step S2d is six.

In the first step S1d, the first sampling process Us, the third sampling process Ws, the second sampling process Vs, the third sampling process Ws, the second sampling process Vs, and the third sampling process Ws are executed in succession in this order. In the second step S2d, the third sampling process Ws, the second sampling process Vs, the third sampling process Ws, the second sampling process Vs, the third sampling process Ws, and the first sampling process Us are executed in succession in this order.

In the third step in the example of FIG. 9, for each of the multiple analog signals HS, the sampling data obtained in the first step S1d and the sampling data obtained in the second step S2d are added together and divided by the total number of sampling processes Sp corresponding to each analog signal HS to calculate a digital signal value. This makes it possible to calculate a digital signal value corresponding to the digital signal value acquired at timing Ta for each of the multiple analog signals HS.

9, the sampling data obtained in the sampling process Sp in the first step S1d and the sampling data obtained in the first sampling process Us in the second step S2d are added together, and the sum is divided by the total number of the first sampling process Us, i.e., 2, to calculate the value of the digital signal corresponding to the first analog signal Hu. In the third step in the example of FIG. 9, the sampling data obtained in the second sampling process Vs in the first step S1d and the sampling data obtained in the second sampling process Vs in the second step S2d are added together, and the sum is divided by the total number of the second sampling process Vs, i.e., 4, to calculate the value of the digital signal corresponding to the second analog signal Hv. In the third step in the example of FIG. 9, the value obtained by adding the sampling data obtained in the third sampling process Ws in the first step S1d and the sampling data obtained in the third sampling process Ws in the second step S2d is divided by the total number of times the third sampling process Ws was performed, i.e., 6, to calculate the value of the digital signal corresponding to the third analog signal Hw.

The method of calculating the value of the digital signal in the third step is not particularly limited as long as it is based on the sampling data obtained in the first step and the sampling data obtained in the second step. The value of the digital signal calculated in the third step may be a value obtained by adding up the sampling data obtained in the first step and the sampling data obtained in the second step for each of the multiple analog signals and dividing the sum by the total number of sampling processes performed in the first step and the second step. The sampling data obtained in the first step may not be a sum of values obtained from multiple samplings, but may be multiple values obtained from multiple samplings. The sampling data obtained in the second step may not be a sum of values obtained from multiple samplings, but may be multiple values obtained from multiple samplings.

The calculation unit of the position detection device may be capable of simultaneously converting multiple analog signals into digital signals. The object whose rotational position is detected by the position detection method and the position detection device is not limited to the rotor of a motor, but is not particularly limited as long as it is a rotating body. When the target rotating body is a rotor of a motor, the motor may be any type of motor. The motor may be a multi-phase motor other than a three-phase motor. The rotation sensor that detects the rotational position of the rotating body is not limited to a magnetic sensor, but may be any type of sensor. The rotation sensor may be, for example, an optical sensor. The number of analog signals converted into digital signals by the signal conversion method of the present invention is not particularly limited as long as it is two or more.

The present technology can be configured as follows.
(1) A signal conversion method for converting each of a plurality of analog signals into a digital signal, the signal conversion method comprising: a first step of sequentially performing a sampling process for sampling the values of the analog signals at least once a plurality of times; and a second step subsequent to the first step of sequentially performing the sampling process a plurality of times, the plurality of sampling processes performed in the first step including at least one sampling process for each of the plurality of analog signals, and the second step of performing the plurality of sampling processes performed in the first step in a reverse order to that of the first step.
(2) The signal conversion method according to (1), further comprising a third step of calculating, for each of the plurality of analog signals, a value of a digital signal based on the sampling data obtained in the first step and the sampling data obtained in the second step.
(3) The signal conversion method according to (2), wherein the third step includes adding up, for each of the plurality of analog signals, the sampling data obtained in the first step and the sampling data obtained in the second step.
(4) The signal conversion method according to (2) or (3), wherein the plurality of sampling processes performed in the first step include the same number of sampling processes for each of the plurality of analog signals.
(5) A position detection method for detecting a rotational position of a rotating body, the position detection method including: acquiring a plurality of analog signals having different phases from each other by a plurality of rotation sensors capable of outputting analog signals according to the rotational position of the rotating body; and performing a detection step of detecting the rotational position of the rotating body based on the plurality of analog signals at a predetermined period, the detection step including: a conversion step of converting each of the plurality of analog signals into a digital signal by a signal conversion method described in any one of (2) to (4); and a calculation step of calculating the rotational position of the rotating body based on the digital signal obtained in the conversion step.
(6) The position detection method described in (5), wherein the detection step performed for the second time or later includes calculating an estimate of a digital signal obtained based on a value of the analog signal after a first predetermined time from a timing at which the first step and the second step are switched based on a value of the digital signal obtained in the third step and a value of the digital signal obtained in the third step of the detection step performed immediately before.
(7) The position detection method according to (6), wherein, in the detection step performed for the second or subsequent time, the estimated value of the digital signal is calculated by the following formula (1), where ts is the specified period, tpa is the first specified time, D[M] is a value of the digital signal obtained in the Mth detection step, and De is an estimated value of the digital signal.
De=D[M]+(D[M]-D[M-1])/ts×tpa...Formula (1)
(8) The position detection method according to (6) or (7), wherein the first predetermined time is equal to a time from a timing at which the first step and the second step are switched to a time at which the rotational position of the rotating body is calculated in the calculation step.
(9) The position detection method described in (5), wherein the detection step performed for the second or subsequent time includes calculating an estimate of the rotational position of the rotating body after a second predetermined time based on the rotational position of the rotating body obtained in the calculation step and the rotational position of the rotating body obtained in the calculation step of the detection step performed one time previously.
(10) A position detection method according to (9), in which, when the specified period is ts, the second specified time is tpb, the rotational position of the rotating body obtained in the Mth detection step is θ[M], and the estimated value of the rotational position of the rotating body is θe, in the detection step performed for the second time or later, an estimated value of the rotational position of the rotating body is calculated by the following equation (2):
θe=θ[M]+(θ[M]-θ[M-1])/ts×tpb...Formula (2)
(11) The position detection method according to (9) or (10), in which the second predetermined time is equal to a time from a timing at which the first step and the second step are switched to a timing at which the estimated value is calculated.
(12) A position detection device for detecting a rotational position of a rotating body, comprising: a plurality of rotation sensors capable of outputting analog signals which are analog signals corresponding to the rotational position of the rotating body and have mutually different phases; and a calculation unit capable of executing, at a predetermined cycle, a detection step for detecting the rotational position of the rotating body based on the plurality of analog signals output from the plurality of rotation sensors, wherein in the detection step, the calculation unit executes a conversion step for converting each of the plurality of analog signals into a digital signal, and a calculation step for calculating the rotational position of the rotating body based on the digital signal obtained in the conversion step, and in the conversion step, the calculation unit samples the value of the analog signal at least once. a first step of sequentially performing a sampling process multiple times, a second step which is performed subsequent to the first step and sequentially performs the sampling process multiple times, and a third step of calculating, for each of the plurality of analog signals, a value of a digital signal based on sampling data obtained in the first step and sampling data obtained in the second step, wherein the multiple sampling processes performed in the first step include the sampling process for each of the plurality of analog signals at least once, and in the second step, the calculation unit performs the multiple sampling processes performed in the first step in a reverse order to that of the first step.
(13) The position detection device according to (12), wherein in the third step, the calculation unit adds together the sampling data obtained in the first step and the sampling data obtained in the second step for each of the plurality of analog signals.
(14) The position detection device according to (13), wherein the plurality of sampling processes performed in the first step include the same number of sampling processes for each of the plurality of analog signals.
(15) A position detection device described in any one of (12) to (14), wherein in the detection step performed for the second time or later, the calculation unit calculates an estimate of the digital signal obtained based on the value of the analog signal after a first predetermined time from a timing at which the first step and the second step are switched based on the value of the digital signal obtained in the third step and the value of the digital signal obtained in the third step of the detection step performed one step before.
(16) The position detection device according to (15), wherein the first predetermined time is equal to a time from a timing at which the first step and the second step are switched to a time at which the rotational position of the rotating body is calculated in the calculation step.
(17) A position detection device described in any one of (12) to (14), wherein in the detection step performed for the second time or later, the calculation unit calculates an estimate of the rotational position of the rotating body after a second specified time based on the rotational position of the rotating body obtained in the calculation step and the rotational position of the rotating body obtained in the calculation step of the detection step performed one time previously.
(18) The position detection device according to (17), wherein the second predetermined time is equal to a time from a timing at which the first step and the second step are switched to a timing at which the estimated value is calculated.
(19) The position detection device according to any one of (12) to (18), further comprising a magnet provided on the rotating body, wherein the rotation sensor is a magnetic sensor capable of detecting a magnetic field of the magnet.

The configurations and methods described in this specification can be combined as appropriate within the limits of not being mutually inconsistent.

20...rotor (rotating body), 30...magnet, 40...rotation sensor, 51...calculation unit, 100...position detection device, De, θe...estimated value, HS...analog signal, S1a, S1b, S1c, S1d...first step, S2a, S2b, S2c, S2d...second step, S3a...third step, Sca1, Sca2...calculation step, Scv...conversion step, Sd1, Sd2...detection step, Sp...sampling process, Ta...timing, tpa...first predetermined time, tpb...second predetermined time, ts...period

Claims (19)

1. A signal conversion method for converting a plurality of analog signals into digital signals, comprising the steps of:
a first step of sequentially performing a sampling process for sampling the value of the analog signal at least once a plurality of times;
a second step, which is performed successively after the first step, of sequentially performing the sampling process a plurality of times;
Including,
The plurality of sampling processes performed in the first step include the plurality of sampling processes for each of the plurality of analog signals at least once,
In the second step, the sampling process is performed a plurality of times in a reverse order to that in the first step. The signal conversion method according to claim 1, further comprising a third step of calculating a digital signal value for each of the plurality of analog signals based on the sampling data obtained in the first step and the sampling data obtained in the second step. The signal conversion method according to claim 2, wherein the third step includes adding together the sampling data obtained in the first step and the sampling data obtained in the second step for each of the multiple analog signals. The signal conversion method according to claim 3, wherein the multiple sampling processes performed in the first step include the same number of sampling processes for each of the multiple analog signals. A position detection method for detecting a rotational position of a rotating body, comprising:
acquiring a plurality of analog signals having mutually different phases by a plurality of rotation sensors capable of outputting analog signals according to a rotational position of the rotating body;
a detection step of detecting a rotational position of the rotating body based on the plurality of analog signals at a predetermined period;
Including,
The detection step includes:
A conversion step of converting each of the plurality of analog signals into a digital signal by a signal conversion method according to any one of claims 2 to 4;
a calculation step of calculating a rotational position of the rotating body based on the digital signal obtained in the conversion step;
A location detection method comprising: The position detection method according to claim 5, wherein the detection step performed for the second or subsequent time includes calculating an estimate of the digital signal obtained based on the value of the analog signal after a first predetermined time from the timing of switching between the first step and the second step, based on the value of the digital signal obtained in the third step and the value of the digital signal obtained in the third step of the detection step performed immediately before. 7. The position detection method according to claim 6, wherein, when the predetermined period is ts, the first predetermined time is tpa, the value of the digital signal obtained in the Mth detection step is D[M], and an estimated value of the digital signal is De, in the detection step performed for the second time or later, the estimated value of the digital signal is calculated by the following formula (1):
De=D[M]+(D[M]-D[M-1])/ts×tpa...Formula (1) The position detection method according to claim 6, wherein the first predetermined time is equal to the time from when the first step and the second step switch to when the rotational position of the rotating body is calculated in the calculation step. The position detection method according to claim 5, wherein the detection step performed for the second or subsequent time includes calculating an estimate of the rotational position of the rotating body after a second predetermined time based on the rotational position of the rotating body obtained in the calculation step and the rotational position of the rotating body obtained in the calculation step of the detection step performed one time before. 10. The position detection method of claim 9, wherein, when the predetermined period is ts, the second predetermined time is tpb, the rotational position of the rotating body obtained in the Mth detection step is θ[M], and the estimated value of the rotational position of the rotating body is θe, in the detection step performed for the second time or later, the estimated value of the rotational position of the rotating body is calculated by the following equation (2):
θe=θ[M]+(θ[M]-θ[M-1])/ts×tpb...Formula (2) The position detection method according to claim 9, wherein the second predetermined time is equal to the time from when the first step switches to the second step until the estimated value is calculated. A position detection device for detecting a rotational position of a rotating body, comprising:
a plurality of rotation sensors capable of outputting analog signals which correspond to a rotational position of the rotating body and have mutually different phases;
a calculation unit capable of executing a detection step of detecting a rotational position of the rotating body based on a plurality of analog signals output from the plurality of rotation sensors at a predetermined interval;
Equipped with
In the detection step, the calculation unit
a conversion step of converting each of the plurality of analog signals into a digital signal;
a calculation step of calculating a rotational position of the rotating body based on the digital signal obtained in the conversion step;
Run
In the conversion step, the calculation unit
a first step of sequentially performing a sampling process for sampling the value of the analog signal at least once a plurality of times;
a second step, which is performed successively after the first step, of sequentially performing the sampling process a plurality of times;
a third step of calculating a value of a digital signal for each of the plurality of analog signals based on the sampling data obtained in the first step and the sampling data obtained in the second step;
Run
The plurality of sampling processes performed in the first step include the plurality of sampling processes for each of the plurality of analog signals at least once,
In the second step, the calculation unit performs the sampling process multiple times in an order reverse to that in the first step. The position detection device according to claim 12, wherein in the third step, the calculation unit adds together the sampling data obtained in the first step and the sampling data obtained in the second step for each of the multiple analog signals. The position detection device according to claim 13, wherein the multiple sampling processes performed in the first step include the same number of sampling processes for each of the multiple analog signals. The position detection device according to claim 12, wherein in the detection step performed for the second or subsequent time, the calculation unit calculates an estimate of the digital signal obtained based on the value of the analog signal after a first predetermined time from the timing at which the first step and the second step are switched, based on the value of the digital signal obtained in the third step and the value of the digital signal obtained in the third step of the detection step performed immediately before. The position detection device according to claim 15, wherein the first predetermined time is equal to the time from when the first step and the second step switch to when the rotational position of the rotating body is calculated in the calculation step. The position detection device according to claim 12, wherein in the detection step performed for the second or subsequent time, the calculation unit calculates an estimate of the rotational position of the rotating body after a second predetermined time based on the rotational position of the rotating body obtained in the calculation step and the rotational position of the rotating body obtained in the calculation step of the detection step performed one time before. The position detection device according to claim 17, wherein the second predetermined time is equal to the time from when the first step and the second step switch to when the estimated value is calculated. A magnet is provided on the rotor,
The position detection device according to claim 12 , wherein the rotation sensor is a magnetic sensor capable of detecting a magnetic field of the magnet.

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