JP2021083257A - Magnetic pole direction detection device and magnetic pole direction detection method - Google Patents

Abstract

To provide a highly accurate magnetic pole direction detecting device for magnetic pole detection of a synchronous motor having a salience.SOLUTION: A magnetic pole direction detection device comprises: a high-frequency voltage application unit 2 that applies a high-frequency voltage to a motor 10; an excitation phase change unit 3 that changes the excitation phase of the motor 10 to an arbitrary phase; a drive current detection unit 4 that detects the drive current value of the motor 10; a magnetic pole direction estimation unit 5 that estimates the magnetic pole direction of the motor 10 on the basis of the excitation phase and the drive current value when the high frequency voltage is applied to the motor 10; a variation calculation unit 6 that calculates the variation of the magnetic pole direction estimation result estimated by the magnetic pole direction estimation unit 5; a determination unit 7 that determines whether the variation is larger than a predetermined threshold value; and a control unit 8 that, on the basis of the determination result of the determination unit 7, outputs the magnetic pole direction estimation result as the magnetic pole direction detection result of a motor 10 when the variation is equal to or less than the predetermined threshold value, and changes the frequency of the high frequency voltage applied by the high-frequency voltage application unit 2 and repeatedly retries the magnetic pole direction detection until the variation becomes the predetermined threshold value or less when the variation is larger than the predetermined threshold value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a magnetic pole direction detection device.

Conventionally, in a synchronous motor having a salient polarity, there is a method of detecting magnetic poles while the motor is stopped. Patent Document 1 discloses a technique of measuring the feedback current value in each phase and estimating the magnetic pole direction from the magnitude when a high frequency voltage having a small amplitude is applied to the motor while changing the excitation phase of the motor. ing.

Japanese Unexamined Patent Publication No. 2005-130582

However, when the order of the inductance value is large, the obtained feedback current value becomes small, and it becomes easily affected by noise. Therefore, an error is likely to occur in the detection result of the magnetic pole direction, and the detection result has a large variation even if the magnetic pole direction is estimated a plurality of times.

One aspect of the present disclosure is a magnetic pole direction detecting device (for example, a magnetic pole direction detecting device 1 described later) for detecting the magnetic pole direction of a synchronous motor having a salient pole (for example, the electric motor 10 described later) with respect to the electric motor. A high-frequency voltage application unit (for example, a high-frequency voltage application unit 2 described later) for applying a high-frequency voltage and an excitation phase change unit (for example, an excitation phase change unit 3 described later) for changing the excitation phase of the motor to an arbitrary phase. And the magnetic pole direction based on the drive current detection unit (for example, the drive current detection unit 4 described later) that detects the drive current value of the motor, the excitation phase, and the drive current value under the application of the high frequency voltage. A magnetic pole direction estimation unit that executes estimation (for example, a magnetic pole direction estimation unit 5 described later) and a variation calculation unit that calculates variations in the magnetic pole direction estimation results estimated by the magnetic pole direction estimation unit (for example, variation calculation described later). The variation is based on the determination result of the determination unit, the unit 6), the determination unit for determining whether or not the variation calculated by the variation calculation unit is larger than a predetermined threshold value (for example, the determination unit 7 described later), and the determination result of the determination unit. Is equal to or less than a predetermined threshold value, the magnetic pole direction estimation result is output as the magnetic pole direction detection result of the motor, and if the variation is larger than the predetermined threshold value, the high frequency voltage applied by the high frequency voltage application unit is applied. Provided is a magnetic pole direction detecting device including a control unit (for example, a control unit 8 described later) that retries the estimation of the magnetic pole direction by changing the frequency of the magnetic pole direction.

Further, one aspect of the present disclosure is a magnetic pole direction detection method for detecting the magnetic pole direction of a synchronous electric motor having salient poles, in which a high-frequency voltage application step of applying a high-frequency voltage to the electric motor and an excitation phase of the electric motor are set. The magnetic pole direction is estimated based on the excitation phase change step of changing to an arbitrary phase, the drive current detection step of detecting the drive current value of the electric motor, the excitation phase, and the drive current value under the application of the high frequency voltage. The magnetic pole direction estimation step for executing the above, the variation calculation step for calculating the variation of the magnetic pole direction estimation result estimated by the magnetic pole direction estimation unit, and whether or not the variation calculated by the variation calculation unit is larger than a predetermined threshold value. When the variation is equal to or less than a predetermined threshold value based on the determination result of the determination step, the magnetic pole direction estimation result is output as the magnetic pole direction detection result of the electric motor. When the variation is larger than a predetermined threshold value, the frequency of the high frequency voltage applied in the high frequency voltage application step is changed to change the high frequency voltage application step, the excitation phase change step, and the drive current detection step. The magnetic pole direction detecting method is provided, which retries the magnetic pole direction estimation step, the variation calculation step, and the determination step.

According to the present invention, it is possible to provide a highly accurate magnetic pole direction detecting device in magnetic pole detection of a synchronous motor having a salient polarity.

It is a block diagram which shows the structure of the magnetic pole direction detection apparatus which concerns on one Embodiment of this invention. It is explanatory drawing explaining the magnetic pole direction in the embedded magnet type motor. It is explanatory drawing explaining the magnetic pole direction in a reluctance type electric motor. It is explanatory drawing about the relationship between the inductance and the current-time differential value in an embedded magnet type motor. It is explanatory drawing about the relationship between the inductance and the current-time differential value in a reluctance type motor. It is a figure which shows the current value with respect to the change of the excitation phase. It is a graph which shows the estimated magnetic pole direction at the time of applying a high frequency voltage of a high frequency. It is a graph which shows the estimated magnetic pole direction at the time of applying a high frequency voltage of a low frequency. It is a graph which shows the relationship between the current time derivative value and the current value at the time of applying a high frequency voltage of a high frequency. It is a graph which shows the relationship between the current time derivative value and the current value at the time of applying a high frequency voltage of a low frequency. It is a graph explaining the current value dependence of the inductance. It is a flowchart explaining the magnetic pole direction detection method which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited thereto.

FIG. 1 is a block diagram showing a configuration of a magnetic pole direction detection device according to an embodiment of the present invention.
The magnetic pole direction detection device 1 of the present embodiment includes a high-frequency voltage application unit 2, an exciting phase change unit 3, a drive current detection unit 4, a magnetic pole direction estimation unit 5, a variation calculation unit 6, and a determination unit 7. A control unit 8 and a magnetic pole position detection unit 9 are provided. The magnetic pole direction detecting device 1 can detect the magnetic pole direction of the synchronous motor 10 having a salient polarity with high accuracy.

The synchronous motor 10 to be detected in the magnetic pole direction is not particularly limited as long as it has a salient pole. For example, the iron core 12 is arranged on the rotor 11 as shown in FIG. 2A, and the permanent magnet 13 is inside. It may be an embedded magnet type electric motor 10 or a reluctance type electric motor 20 in which only the iron core 22 is arranged on the rotor 21 as shown in FIG. 2B. In these motors 10 and 20, the inductance around the rotation axis of the rotors 11 and 21 differs due to the asymmetry of the iron cores 12 and 22 and the permanent magnets 13 arranged in the rotors 11 and 21. Hereinafter, an embodiment in which the embedded magnet type motor 10 is mainly targeted for detection will be described, and a case where the reluctance type motor 20 is appropriately targeted for detection will also be described.

The high frequency voltage application unit 2 can apply a high frequency voltage to the rotor 11 of the motor 10. The exciting phase changing unit 3 changes the exciting phase of the motor 10 to which the high frequency voltage applying unit 2 is applied. The drive current detection unit 4 detects the drive current flowing through the motor 10 by applying a high frequency voltage. The magnetic pole direction estimation unit 5 estimates the magnetic pole direction of the motor 10 based on the excitation phase of the motor 10 and the value of the drive current detected by the drive current detection unit 4 under the application of a high frequency voltage.

The drive current value that flows through the motor 10 due to the application of the high frequency voltage changes depending on the excitation phase of the motor 10 when the high frequency voltage is applied. The exciting phase θ is changed by the exciting phase changing unit 3 in 0 ≦ θ ≦ 180 °, and the driving current value is detected by the driving current detecting unit 4, so that the driving current value i with respect to the exciting phase θ at that voltage frequency You can look up the relationship. The excitation phase of the motor 10 can be changed, for example, by rotating the rotor 11.

Here, the magnetic pole direction detected by the magnetic pole direction detecting device 1 of the present embodiment will be described. As shown in FIG. 2A, the rotation angle of the rotor 11 is θ. When the south pole of the magnet is directed to the rotor 11 from the outside, the angular position θ of the rotor 11 that rotates and faces the south pole is called the magnetic pole position (D phase) of the rotor 11, and the rotation center and the magnetic pole position of the rotor 11 The direction of the straight line (D axis) connecting the magnets is the magnetic pole direction. Further, the Q axis is orthogonal to the D axis in the rotation plane of the rotor 11.
For example, in the rotor 11 of the embedded magnet type electric motor 10 shown in FIG. 2A, the direction extending along the NS pole of the embedded permanent magnet 13 is the magnetic pole direction. Further, in the rotor 21 of the reluctance type electric motor 20 shown in FIG. 2B, the long side direction of the iron core 12 schematically drawn as a rectangle is the magnetic pole direction.

As described above, in the synchronous motor having salient polarity, the D-phase inductance Ld and the Q-phase inductance Lq have different values depending on the asymmetry of the rotor structure. The inductance is an index showing the ease of passage of magnetic flux, and Ld <Lq in the rotor 11 of the embedded magnet type motor 10 and Lq <Ld in the rotor 21 of the reluctance type motor 20.

…（１）
ただし、
Ｌ_０＝（Ｌ_ｄ＋Ｌ_ｑ）／２，
Ｌ_２＝（Ｌ_ｄ−Ｌ_ｑ）／２
θ（ｔ）：時刻ｔにおける印加電圧の位相
θ_ｐ：磁極位置
Ｖｓｉｎγｔ：高周波電圧 The magnetic pole direction detection device 1 of the present embodiment detects the magnetic pole direction based on the amplitude of the current-time derivative value (di / dt) obtained by differentiating the current value i with respect to time t. The current-time differential value can be expressed by the following equation (1), and changes periodically as the excitation phase θ changes.

… (1)
However,
L ₀ = (L _d + L _q ) / 2,
L ₂ = (L _d −L _q ) / 2
θ (t): Phase of applied voltage at time t θ _p : Magnetic pole position Vsinγt: High frequency voltage

As shown in FIGS. 3A and 3B, the magnitude of the inductance is inversely correlated with the magnitude of the amplitude of the current-time derivative value. That is, for example, in the case of the embedded magnet type motor 10, when the amplitude of the current-time differential value takes the minimum value, the inductance takes the maximum value Lq. Further, when the amplitude of the current-time derivative value takes a maximum value, the inductance takes a minimum value Ld (FIG. 3A). In the case of the reluctance type motor 20, when the amplitude of the current-time differential value takes the minimum value, the inductance takes the maximum value Ld. Further, when the amplitude of the current-time derivative value takes a maximum value, the inductance takes a minimum value Lq (FIG. 3B).

Therefore, the magnetic pole direction is estimated by detecting the minimum or maximum value of the amplitude of the current-time differential value while changing the excitation phase θ with time t at 0 ° ≤ θ ≤ 360 ° and outputting the excitation phase at that time. can do. Specifically, in the case of the above-mentioned embedded magnet type motor 10, the inductance takes Ld when the amplitude of the current-time differential value takes the maximum value. Assuming that the excitation phase at that time is θ ₁ , θ ₁ + n × 180 ° (0 ° ≤ θ ₁ ≤ 180 °, n is an integer) is the magnetic pole direction. In the case of the reluctance type motor 20, the inductance takes Ld when the amplitude of the current-time differential value takes a minimum value. Assuming that the excitation phase at that time is θ ₂ , θ ₂ + n × 180 ° (0 ° ≤ θ ₂ ≤ 180 °, n is an integer) is the magnetic pole direction.

FIG. 4 is a graph showing the relationship between the drive current value and the excitation phase. Under constant high-frequency voltage application, changes in the current-time differential value and the excitation phase θ are observed over time, and the magnetic pole direction is estimated based on the excitation phase θ when the amplitude of the current-time differential value takes the minimum value.

The current-time derivative value changes periodically as θ increases, and its maximum value and minimum value appear twice each per lap. Therefore, by estimating and averaging the values of the exciting phases θ related to the plurality of maximum and minimum values, the magnetic pole direction can be estimated with higher accuracy. Therefore, the exciting phase can be changed by one or more turns to change the magnetic poles. It is preferable to estimate the direction. The processing of the values of the plurality of excitation phases θ is not limited to averaging, and may be processed by another method.

The magnetic pole direction may be estimated by detecting either the maximum value or the minimum value of the amplitude of the current-time differential value, but it is particularly preferable to detect the maximum value. This is because the amplitude of the current-time differential value changes sharply when the maximum value is compared with the minimum value, so that it is not easily affected by noise and the detection accuracy is improved. In the case of the embedded magnet type motor 10 in which Ld <Lq, the excitation phase having the detected maximum value is estimated to be the magnetic pole direction as it is. In the case of the reluctance type motor 20 in which Lq <Ld, the phase shifted by 90 ° from the excitation phase having the detected maximum value is estimated to be the magnetic pole direction. In this way, for example, the rotor 11 is rotated S and the maximum value that appears 2S times is detected, and the magnetic pole direction is estimated.

The variation calculation unit 6 calculates variations from the magnetic pole direction estimation results related to the detected 2S maximum values. When the variation calculation result is smaller than a predetermined threshold value set in advance, the magnetic pole direction estimation result is considered to have sufficient accuracy and is output as the magnetic pole direction detection result. If the variation calculation result is smaller than a predetermined threshold value set in advance, the frequency of the high frequency voltage is changed and the magnetic pole direction estimation is retried. This is repeated until the variation in the magnetic pole direction estimation result becomes equal to or less than the threshold value. This makes it possible to detect the magnetic pole direction with high accuracy. The method of taking the standard of the magnitude of variation is not particularly limited, and for example, the variance of 2S values may be used as a reference, or the difference between the maximum phase and the minimum phase of the 2S phases may be used as a reference.

On the other hand, if the current value becomes too large, there will be an adverse effect such as an increase in heat generation of the motor 10, so it is preferable to change the frequency of the applied voltage within a range of an appropriate current value as the current applied to the motor 10. Further, when the motor 10 has a limiter and an upper limit of the current value flowing through the motor 10 is set to prevent overcurrent, if the current value becomes too large, the change over time will be accurate. It cannot be measured, and the maximum and minimum values of the current-time differential value cannot be detected with high accuracy. Therefore, in this case, it is preferable to change the frequency of the applied voltage within a range in which the current value is less than the set upper limit value.

5A and 5B show the results of estimating the magnetic pole direction by changing the frequency of the high frequency voltage. FIG. 5B shows the result when a high frequency voltage having a frequency lower than that of FIG. 5A is applied. In FIG. 5B, the detected current value is larger and the variation in the estimated magnetic pole direction is smaller.

When the frequency of the applied high-frequency voltage is further changed and the frequency is lowered, the current value increases, so that the magnetic pole direction can be detected with higher accuracy. This will be described in detail. 6A and 6B are graphs showing the time-dependent differential value and the change over time of the current value side by side, and FIG. 6B shows the result when a high frequency voltage having a frequency lower than that of FIG. 6A is applied. t ₁ and t ₂ represent the time t which is a half cycle, and i ₁ and i ₂ represent the amplitude of the current i, and t ₁ <t ₂ and i ₁ <i ₂ .

From the equation (1), since the amplitude of the current-time differential value depends only on θ and the inductance, it is constant even if the frequency of the high frequency voltage is reduced. On the other hand, as the frequency becomes lower, the wavelength becomes larger, so that t ₂ becomes larger than t _1. As a result, as the frequency of the applied voltage becomes lower, the area of the shaded portion of the graph of the current-time differential value becomes larger. Since the current-time derivative graph is obtained by differentiating the current value graph with respect to time, the area of the shaded portion of the current-time derivative graph represents the magnitude of the amplitude of the corresponding current value graph. Therefore, when the frequency of the applied high frequency voltage is further changed and the frequency is lowered, the current value increases.

When the motor to be detected is an embedded magnet type motor 10, it is preferable that the magnetic pole position can be further detected by the magnetic pole position detecting unit 9. As a method for detecting the magnetic pole position, a conventionally known method can be used, and for example, it can be detected by the following method. First, an external magnetic field is applied to the electric motor 10 in parallel with the magnetic pole direction detected by the magnetic pole direction detecting device 1. Subsequently, the sign of the external magnetic field is inverted. When the application direction of the external magnetic field is the same direction as the magnetic field formed by the permanent magnet 13, magnetic saturation occurs and the inductance decreases as compared with the case where the magnetic field in the opposite direction is applied, so that the change in the current value changes. growing. By utilizing this property, the position of the magnetic pole can be detected.

Further, as shown in FIG. 7, the inductance value depends on the current value, and the inductance value decreases as the current value increases. That is, the larger the amplitude of the current-time differential value is, the larger the current value is and the lower the inductance is, so that the amplitude of the current-time differential value is further increased. As a result, the amplitude of the current-time differential value changes steeper than the minimum value at the maximum value, so that it is not easily affected by noise, and the magnetic pole direction can be detected with high accuracy.

Hereinafter, an example of magnetic pole direction detection according to the present embodiment will be described with reference to the flowchart of FIG.

First, the threshold value of the variation calculation result is set according to the target accuracy (step S1). Next, in the high-frequency voltage application step, the high-frequency voltage application unit 2 applies a high-frequency voltage of frequency A to the rotor 11 of the motor 10 (step S2). Next, in the exciting phase changing step, the exciting phase θ of the electric motor 10 is changed in S circumference by the exciting phase changing unit 3, and the driving current flowing through the electric motor 10 is detected by the driving current detecting unit 4 in the driving current detecting step. Next, in the magnetic pole direction detection step, the magnetic pole direction estimation unit 5 estimates the magnetic pole direction of the motor 10 based on the drive current detected 2S times by the drive current detection unit 4 and the excitation phase θ at that time. Next, in the variation calculation step, the variation calculation unit 6 calculates the variation in the estimated magnetic pole direction at the applied voltage of the frequency A (step S3).

Subsequently, the determination unit 7 compares the variation result σ (A) calculated for the applied voltage of the frequency A with the threshold value set in step S1 (step S4). When the variation is equal to or less than a predetermined threshold value, the magnetic pole direction estimation result related to the variation result σ (A) is output as the magnetic pole direction detection result of the motor 10 (step S6). If the variation result σ (A) is larger than a predetermined threshold value, the frequency of the high frequency voltage applied in the high frequency voltage application step is changed to a frequency B lower than the frequency A, and steps S2 to S4 are retried. (Step S5).

This is repeated by lowering the frequency of the applied voltage until the variation becomes equal to or less than a predetermined threshold value, and when the variation becomes equal to or less than a predetermined threshold value, the magnetic pole direction estimation result related to the inductance value is output as the magnetic pole direction detection result. (Step S6).

Regarding the variation results, for example, the estimated magnetic pole directions of each of the eight frequencies A, B, and C were as follows.
A (40 °, 42 °, 43 °, 61 °, 58 °, 56 °, 42 °, 59 °) Variance 72.4
B (40 °, 48 °, 52 °, 49 °, 70 °, 50 °, 48 °, 49 °) Variance 63.7
Taking the variance of eight values as a reference, the variation result σ (A) = 72.4 and the variation result σ (B) = 63.7. If the threshold value is set with reference to the variance 70, the variation in the magnetic pole direction estimation result at the frequency A exceeds the threshold value, so the frequency is changed to a lower frequency B and the magnetic pole direction estimation is retried. Since the variation in the magnetic pole direction estimation result at the frequency B is equal to or less than the threshold value, the magnetic pole direction estimation result is output as the magnetic pole direction detection result of the motor 10. The magnetic pole direction θ _B is an average value of eight values of 51 ° (rounded to the first decimal place).

As a result, a highly accurate magnetic pole direction detection result with little variation can be obtained. When the motor to be detected is an embedded magnet type motor 10, the magnetic pole position detection unit 9 further applies an external magnetic field to the motor 10 in both directions parallel to the magnetic pole direction after step S6. , Further, the magnetic pole position may be detected.

The magnetic pole direction detecting device 1 which is one aspect of the present invention has been described above. According to the present invention, the following effects can be obtained.

One aspect of the present invention is a magnetic pole direction detecting device 2 for detecting the magnetic pole direction of the synchronous electric motor 10 having a salient pole, and the high-frequency voltage applying unit 2 for applying a high-frequency voltage to the electric motor 10 and the excitation of the electric motor 10. Based on the excitation phase change unit 3 that changes the phase to an arbitrary phase, the drive current detection unit 4 that detects the drive current value of the electric motor 10, the excitation phase, and the drive current value under the application of the high frequency voltage. The magnetic pole direction estimation unit 5 that executes the magnetic pole direction estimation, the variation calculation unit 6 that calculates the variation of the magnetic pole direction estimation result estimated by the magnetic pole direction estimation unit 5, and the variation calculated by the variation calculation unit 6 are predetermined. Based on the determination unit 7 for determining whether or not it is larger than the threshold value and the determination result of the determination unit 7, when the variation is equal to or less than a predetermined threshold value, the magnetic pole direction estimation result is the magnetic pole direction detection result of the electric motor 10. When the variation is larger than a predetermined threshold value, the magnetic pole direction detection includes a control unit 8 that changes the frequency of the high frequency voltage applied by the high frequency voltage application unit 2 and retries the estimation of the magnetic pole direction. The device 1 is provided. This enables highly accurate detection of the magnetic pole direction.

The magnetic pole direction detecting device 1 further includes a magnetic pole position detecting unit 9 capable of applying an external magnetic field to the motor 10 in both directions parallel to the detected magnetic pole direction. As a result, the magnetic pole position can be detected with high accuracy.

In the magnetic pole direction detection device 1, the exciting phase changing unit 3 further rotates the electric motor 10 around S (S is an integer of 1 or more). As a result, the accuracy of the variation calculation is improved, so that the magnetic pole direction can be detected with higher accuracy.

In the magnetic pole direction detection device 1, the magnetic pole direction estimation unit 5 further detects the exciting phase at which the drive current-time differential value becomes maximum, and when Ld <Lq, the exciting phase is used, and when Lq <Ld, the magnetizing phase is concerned. The phase changed by 90 ° from the exciting phase is estimated as the magnetic pole direction. As a result, the accuracy of current value detection is improved, so that the magnetic pole direction can be detected with higher accuracy.

Further, one aspect of the present disclosure is a magnetic pole direction detection method for detecting the magnetic pole direction of a synchronous motor having salient poles, wherein a high frequency voltage application step of applying a high frequency voltage to the motor and an excitation phase of the motor The magnetic pole direction is estimated based on the excitation phase change step of changing to an arbitrary phase, the drive current detection step of detecting the drive current value of the motor, the excitation phase, and the drive current value under the application of the high frequency voltage. The magnetic pole direction estimation step for executing the above, the variation calculation step for calculating the variation of the magnetic pole direction estimation result estimated in the magnetic pole direction estimation step, and whether or not the variation calculated by the variation calculation step is larger than a predetermined threshold value When the variation is equal to or less than a predetermined threshold value based on the determination result of the determination step, the magnetic pole direction estimation result is output as the magnetic pole direction detection result of the motor. When the variation is larger than a predetermined threshold value, the frequency of the high frequency voltage applied in the high frequency voltage application step is changed until the variation becomes equal to or less than the predetermined threshold value. Provided is the magnetic pole direction detection method in which the variation calculation step and the determination step are repeatedly retried. This enables highly accurate detection of the magnetic pole direction.

1 ... Magnetic pole direction detection device 2 ... High-frequency voltage application unit 3 ... Excitation phase change unit 4 ... Drive current detection unit 5 ... Magnetic pole direction estimation unit 6 ... Variation calculation unit 7 ... Judgment unit 8 ... Control unit 9 ... Magnetic pole position detection unit 10 , 20 ... Motor 11,21 ... Rotor 12,22 ... Iron core 13 ... Permanent magnet

Claims (5)

A magnetic pole direction detection device that detects the magnetic pole direction of a synchronous motor having salient polarity.
A high-frequency voltage application unit that applies a high-frequency voltage to the motor,
An exciting phase changing unit that changes the exciting phase of the motor to an arbitrary phase,
A drive current detection unit that detects the drive current value of the motor,
A magnetic pole direction estimation unit that executes magnetic pole direction estimation based on the excitation phase and the drive current value under the application of the high frequency voltage.
A variation calculation unit that calculates the variation of the magnetic pole direction estimation result estimated by the magnetic pole direction estimation unit, and a variation calculation unit.
A determination unit that determines whether or not the variation calculated by the variation calculation unit is larger than a predetermined threshold value.
When the variation is equal to or less than a predetermined threshold value based on the determination result of the determination unit, the magnetic pole direction estimation result is output as the magnetic pole direction detection result of the motor, and when the variation is larger than the predetermined threshold value. Is a magnetic pole direction detecting device including a control unit that changes the frequency of the high frequency voltage applied by the high frequency voltage applying unit and repeatedly retries the estimation of the magnetic pole direction until the variation becomes equal to or less than a predetermined threshold value. The magnetic pole direction detecting device according to claim 1, further comprising a magnetic pole position detecting unit capable of applying an external magnetic field in both directions parallel to the detected magnetic pole direction to the motor. The magnetic pole direction detecting device according to claim 1 or 2, wherein the exciting phase changing unit changes the exciting phase by 360 ° or more. The magnetic pole direction estimation unit detects the exciting phase at which the time differential value of the driving current value becomes maximum, and estimates the phase changed by 90 ° from the detected exciting phase as the magnetic pole direction, according to claims 1 to 3. The magnetic pole direction detection device according to any one of. It is a magnetic pole direction detection method for detecting the magnetic pole direction of a synchronous motor having a salient polarity.
A high-frequency voltage application step of applying a high-frequency voltage to the motor, and
The excitation phase change step of changing the excitation phase of the motor to an arbitrary phase,
The drive current detection process for detecting the drive current value of the motor and
A magnetic pole direction estimation step for executing magnetic pole direction estimation based on the excitation phase and the drive current value under the application of the high frequency voltage.
A variation calculation step for calculating the variation of the magnetic pole direction estimation result estimated by the magnetic pole direction estimation unit, and a variation calculation step.
A determination step for determining whether or not the variation calculated by the variation calculation unit is larger than a predetermined threshold value is provided.
When the variation is equal to or less than a predetermined threshold value based on the determination result of the determination step, the magnetic pole direction estimation result is output as the magnetic pole direction detection result of the motor, and when the variation is larger than the predetermined threshold value. Repeats the magnetic pole direction estimation step, the variation calculation step, and the determination step by changing the frequency of the high frequency voltage applied in the high frequency voltage application step until the variation becomes equal to or less than a predetermined threshold value. The magnetic pole direction detection method to be retried.

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