JP7206832B2 - Rotation angle detector - Google Patents

Description

The present invention relates to a rotation angle detection device for detecting the rotation angle of a rotor of a rotating electric machine.

A rotating electric machine usually has a rotatably provided rotor and a stator with a circuit. The stator generates a predetermined d-axis magnetic flux in the rotor by passing current through its circuit, and applies torque to the rotor by generating a q-axis magnetic flux orthogonal to the d-axis magnetic flux.

A rotation angle detection device for detecting the rotation angle of the rotor of such a rotary electric machine includes a magnet that rotates with the rotor, a detection unit that detects the magnetic flux of the magnet as the detection magnetic flux, and the detection magnetic flux. and a calculation unit for calculating the rotation angle of the rotor based on (see Patent Document 1).

JP-A-11-94512

Depending on the configuration of the rotating electrical machine, the d-axis magnetic flux may leak out from the rotor to the detector side. In that case, the detected magnetic flux includes not only the magnetic flux of the magnet but also the leakage flux of the d-axis magnetic flux. When the angle calculator calculates the rotation angle of the rotor based on the detected magnetic flux including the leakage flux of the d-axis magnetic flux, the calculated rotation angle deviates from the true rotation angle.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and a main object of the present invention is to suppress the influence of the included d-axis magnetic flux even when the d-axis magnetic flux leaks from the rotor and is included in the detected magnetic flux. and

A rotation angle detection device of the present invention detects a rotation angle of a rotor of a rotating electric machine. The rotating electric machine has a rotatable rotor and a stator having a circuit. The stator generates a predetermined d-axis magnetic flux in the rotor and a q-axis magnetic flux orthogonal to the d-axis magnetic flux by applying current to the circuit. The d-axis magnetic flux leaks out of the rotor.

The rotation angle detection device has a magnet, a detection section, a d-axis current acquisition section, and an angle calculation section. The magnet rotates with the rotor. The detection unit detects, as detected magnetic flux, magnetic flux in which leakage magnetic flux from the rotor of the d-axis magnetic flux is superimposed on magnet magnetic flux, which is the magnetic flux of the magnet. The d-axis current acquisition unit acquires a d-axis current value that is a value of a d-axis current that is a component of the current flowing through the circuit that generates the d-axis magnetic flux. The angle calculation section calculates the rotation angle of the rotor based on the detected magnetic flux detected by the detection section and the d-axis current value obtained by the d-axis current acquisition section.

According to the present invention, the angle calculator uses not only the detected magnetic flux but also the d-axis current value to calculate the rotation angle of the rotor. can be predicted. Based on the prediction, the influence of the d-axis magnetic flux contained in the detected magnetic flux can be suppressed.

Schematic diagram showing a rotation angle detection device and a rotating electrical machine of the first embodiment Sectional view showing the same rotation angle detection device and rotating electric machine The perspective view which shows the rotor of the same rotary electric machine. A plan view showing the rotating electric machine Schematic diagram of the rotation angle detection device of FIG. 2 viewed from the right side Schematic diagram showing a state in which the rotor is rotated 45 degrees from the state in FIG. Graph showing relationship between time and temporary rotation angle Schematic diagram showing a rotation angle detection device and a rotating electric machine of a second embodiment Schematic diagram showing a rotation angle detection device and a rotating electric machine according to a third embodiment

Next, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the embodiments, and can be modified as appropriate without departing from the gist of the invention.

[First embodiment]
FIG. 1 is a schematic diagram showing a rotation angle detection device 90 of the first embodiment. A rotation angle detection device 90 is provided for a rotating electric machine 95 .

FIG. 2 is a cross-sectional view showing the rotating electrical machine 95. As shown in FIG. The rotating electrical machine 95 has a rotor 60 and a stator 50 . The rotor 60 is fixed to a rotor shaft 69 and rotates together with the rotor shaft 69 . The rotor 60 is divided into a first core 61 and a second core 62 . Each of the cores 61 and 62 includes substantially cylindrical base portions 61a and 62a and claw-shaped portions 61b extending radially from the base portions 61a and 62a when viewed in the axial direction and then extending toward the other cores 62 and 61 along the axial direction. , 62b. Stator 50 has a housing 51 surrounding rotor 60 . The housing 51 rotatably supports the rotor shaft 69 .

FIG. 3 is a perspective view of the rotor 60 of FIG. 2 as seen obliquely from the right side. With respect to the first core 61, the second core 62 is fixed to the rotor shaft 69 in a state shifted by a center angle corresponding to half the center angle pitch of the claw-shaped portions 62b. Therefore, the claw-shaped portion 62b of the second core 62 is arranged between each two adjacent claw-shaped portions 61b of the first core 61 . A field winding 65 is installed around the bases 61 a and 62 a of the first core 61 and the second core 62 . When a current flows through the field winding 65, a field magnetic flux Φf is generated. The field magnetic flux Φf reaches the base portion 61a of the first core 61 from the claw-shaped portion 61b of the first core 61, passes through the inside of the field winding 65 in the axial direction, and reaches the base portion 62a of the second core 62. , to the claw-shaped portion 62 b of the second core 62 .

FIG. 4 is a schematic diagram of the rotor 60 of FIG. 2 as seen from the right side. 3, each of the cores 61 and 62 has eight claw-like portions 61b and 62b, but FIG. 4 shows four claw-like portions for simplification.

Stator 50 has a circuit 54 with a plurality of coils 55 . The stator 50 generates a d-axis magnetic flux Φd and a q-axis magnetic flux Φq by applying current to the plurality of coils 55 . The d-axis magnetic flux Φd is magnetic flux generated in the same direction as or opposite to the field magnetic flux Φf. Specifically, when the d-axis magnetic flux Φd is generated in the direction opposite to the field magnetic flux Φf as shown in FIG. 4, the magnetic flux generated in the cores 61 and 62 of the rotor 60 is weakened. On the other hand, in contrast to FIG. 4, when the field magnetic flux Φf is generated in the same direction, the magnetic flux generated in the cores 61 and 62 of the rotor 60 is strengthened. The q-axis magnetic flux Φq is magnetic flux generated in a direction orthogonal to the field magnetic flux Φf and the d-axis magnetic flux Φd.

The circuit 54 includes a U-phase, a V-phase, a W-phase, and a phase current detector that detects the current flowing through each phase. The controller of the rotary electric machine 95 calculates a d-axis current value and a q-axis current value based on the current values of the U-phase, V-phase, and W-phase detected by the phase current detection unit. The d-axis current value is the magnitude of the component of the current flowing through the circuit 54 that generates the d-axis magnetic flux Φd. As the d-axis current value increases, the d-axis magnetic flux Φd increases. The q-axis current value is the magnitude of the component of the current flowing through the circuit 54 that generates the q-axis magnetic flux Φq. As the q-axis current value increases, the q-axis magnetic flux Φq increases.

The rotary electric machine 95 includes a current detection section that detects the current flowing through the field winding 65 . Based on the detection, the controller of the rotor 60 acquires the field current value, which is the magnitude of the field current. A field current is a current that flows through the field winding 65 and generates a field magnetic flux Φf. As the field current value increases, the field magnetic flux Φf increases.

As shown in FIG. 2, the field magnetic flux Φf and the d-axis magnetic flux Φd pass through the bases 61a and 62a of the first core 61 and the second core 62 along the rotor shaft 69 in the axial direction. part leaks out to the rotor shaft 69 as disturbance magnetic flux Φn. Then, it leaks out of the housing 51 along the rotor shaft 69 . In particular, when the rotor shaft 69 is made of iron (magnetic material), the leakage amount increases.

The disturbance magnetic flux Φn leaking through the rotor shaft 69 is superimposed on the magnetic flux of the magnet 11 and detected by the detector 12 . As shown in FIG. 2, under the condition that the d-axis magnetic flux Φd is generated in the opposite direction to the field magnetic flux Φf, the magnitude of the disturbance magnetic flux Φn is determined from the magnitude of the leakage flux of the field magnetic flux Φf. It is obtained by subtracting the magnitude of leakage magnetic flux. On the other hand, contrary to FIG. 2, under the condition that the d-axis magnetic flux Φd is generated in the same direction as the field magnetic flux Φf, the magnitude of the disturbance magnetic flux Φn is equal to the magnitude of the leakage magnetic flux of the field magnetic flux Φf. It is obtained by adding the magnitude of the leakage magnetic flux of the magnetic flux Φd.

As shown in FIG. 1 , the rotation angle detection device 90 has a provisional angle calculation circuit 10 , a correction amount calculation circuit 20 , and an angle calculation section 30 . The provisional angle calculation circuit 10 has a magnet 11 , a detection section 12 and a provisional angle calculation section 13 .

As shown in FIG. 2 , the magnet 11 is fixed to the tip of the rotor shaft 69 and rotates together with the rotor shaft 69 . Magnet 11 is a permanent magnet. The detection unit 12 is a sensor that detects magnetic flux and is provided on the side of the extension of the rotor shaft 69 in the axial direction from the magnet 11 . The detected magnetic flux Φ detected by the detection unit 12 includes the magnet magnetic flux Φe generated by the magnet 11 and the disturbance magnetic flux Φn from the rotor 60 .

FIG. 5(a) is a view of the inside of the detection unit 12 in FIG. 2 as viewed from the right side. The detection unit 12 has an A-direction sensor 12a that detects an A-direction component, which is a component of magnetic flux in a predetermined direction, and a B-direction sensor 12b that detects a B-direction component orthogonal to the A direction. Both the A-direction sensor 12 a and the B-direction sensor 12 b are provided at positions slightly displaced from the axis of the rotor shaft 69 . Therefore, the disturbance magnetic flux Φn radially spreading from the axis of the rotor shaft 69 is detected.

Specifically, for example, as shown in FIG. 5A, when the magnet magnetic flux Φe faces the B direction, the B direction sensor 12b detects the magnet magnetic flux Φe. Further, the A-direction sensor 12a detects an A-direction component Φna of the radially spreading disturbance magnetic flux Φn. Further, the B-direction sensor 12b detects a B-direction component Φnb of the radially spreading disturbance magnetic flux Φn.

Therefore, as shown in FIG. 5B, the detection unit 12 generates a magnetic flux in which the A-direction component Φna and the B-direction component Φnb of the disturbance magnetic flux Φn radially spreading are superimposed on the magnet magnetic flux Φe directed in the B direction. It is detected as the detected magnetic flux Φ. Therefore, the direction of the detected magnetic flux Φ deviates from the direction of the magnet magnetic flux Φe.

FIG. 6(a) shows a state in which the magnet magnetic flux Φe is rotated 45 degrees by rotating the rotor 60 by 45 degrees from the state of FIG. 5(a). The A direction sensor 12a detects the A direction component Φea of the magnet flux Φe, and the B direction sensor 12b detects the B direction component Φeb of the magnet flux Φe. At this time, since the magnet magnetic flux Φe is inclined by 45 degrees with respect to both the A-direction sensor 12a and the B-direction sensor 12b, as shown in FIG. It has the same magnitude as the directional component Φeb.

Further, the A-direction sensor 12a detects an A-direction component Φna of the radially spreading disturbance magnetic flux Φn, and the B-direction sensor 12b detects a B-direction component Φnb of the radially spreading disturbance magnetic flux Φn. Since the disturbance magnetic flux Φn spreads radially, the magnitudes of the A-direction component Φna and the B-direction component Φnb are equal.

In this way, the detection unit 12 detects the magnetic flux in which the disturbance magnetic flux Φn is superimposed on the magnet magnetic flux Φe as the detected magnetic flux Φ. However, at this time, the magnitudes of the A-direction component Φea and the B-direction component Φeb of the magnet magnetic flux Φe are equal, and the magnitudes of the A-direction component Φna and the B-direction component Φnb of the disturbance magnetic flux Φn are also equal. The direction of Φ never deviates from the direction of the magnetic flux Φe.

Thereafter, by the same mechanism as above, the direction of the detected magnetic flux Φ deviates from the direction of the magnet magnetic flux Φe or does not deviate. The provisional angle calculator 13 shown in FIG. 1 calculates the provisional rotation angle of the rotor 60 from the direction of the detected magnetic flux Φ. FIG. 7 is a graph showing the relationship between time and provisional rotation angle. Of the two solid curves, the curve C1 with a smaller wave indicates a case where the disturbance magnetic flux Φn is small, and the curve C2 with a larger wave indicates a case where the disturbance magnetic flux Φn is large. A dashed straight line L indicates the true rotation angle of the rotor 60 . A point p5 indicates the state of FIG. 5, and a point p6 indicates the state of FIG.

As shown in FIG. 1, the correction amount calculation circuit 20 includes a magnet strength calculation section 21, a field current acquisition section 23, a d-axis current acquisition section 24, a storage section 27, and a correction amount calculation section 28. .

The magnet strength calculator 21 has a temperature sensor that measures the temperature around the magnet 11, and calculates the magnet strength, which is the magnitude of the magnet magnetic flux Φe, based on the measured temperature. Magnet strength increases as temperature increases, and decreases as temperature decreases.

A field current acquisition unit 23 acquires a field current value from the rotating electric machine 95 . Also, the d-axis current acquisition unit 24 acquires a d-axis current value from the rotary electric machine 95 . The field current value and the d-axis current value acquired here are both measured values, but may be command values.

The storage unit 27 stores relationship data between the field current value and the correction amount and relationship data between the d-axis current value and the correction amount. The correction amount is a value for correcting the curves C1 and C2 (temporary rotation angles) shown in FIG. 7 to the straight line L (true rotation angle). The correction amount calculation unit 28 shown in FIG. 1 calculates the magnet strength calculated by the magnet strength calculation unit 21, the field current value obtained by the field current obtaining unit 23, the d-axis current value obtained by the d-axis current obtaining unit 24, and based on each relational data stored in the storage unit 27, a correction amount is calculated.

The angle calculator 30 calculates the rotation angle of the rotor 60 based on the provisional rotation angle calculated by the provisional angle calculation circuit 10 and the correction amount calculated by the correction amount calculation circuit 20 .

According to this embodiment, the following effects are obtained. Part of the field magnetic flux Φf and the d-axis magnetic flux Φd leaks from the rotor 60 and becomes disturbance magnetic flux Φn, and the disturbance magnetic flux Φn is included in the detected magnetic flux Φ. However, since the angle calculation unit 30 uses not only the detected magnetic flux Φ but also the field current value and the d-axis current value to calculate the rotation angle, the disturbance magnetic flux Φn can be predicted. Based on the prediction, the influence of the disturbance magnetic flux Φn included in the detected magnetic flux Φ can be suppressed.

Further, the provisional angle calculator 13 calculates a provisional rotation angle. According to the provisional rotation angle, a rough rotation angle can be obtained, although it is not accurate. Further, the provisional rotation angle indicates a correct rotation angle at a predetermined time (point p6, etc.) as shown in FIG. Therefore, by temporarily calculating the provisional rotation angle from the detected magnetic flux Φ in this way, it is possible to calculate the true rotation angle while referring to the rough rotation angle, the correct rotation angle at a predetermined time, and the like.

The angle calculation unit 30 uses not only the detected magnetic flux Φ, the field current value, and the d-axis current value to calculate the rotation angle, but also the magnet strength, which is the magnitude of the magnet magnetic flux Φe. , the rotation angle can be calculated accurately.

[Second embodiment]
Next, a rotation angle detection device 90 of a second embodiment will be described with reference to FIG. Regarding this embodiment, only the points that are different from the first embodiment will be described. In addition, in this embodiment and subsequent embodiments, the same reference numerals are assigned to members that are the same as or correspond to those of the previous embodiment.

The rotor 60 does not have a field winding 65, but instead has a rotor magnet, which is a permanent magnet that generates magnetic flux in the same direction as the field magnetic flux Φf. Further, the correction amount calculation circuit 20 does not include the field current acquisition section 23, but instead includes a rotor magnet strength calculation section 23b. The rotor magnet strength calculator 23b has a temperature sensor that measures the temperature around the rotor magnet, and calculates the rotor magnet strength, which is the magnitude of the magnetic flux of the rotor magnet, based on the measured temperature.

The storage unit 27 stores relationship data between the rotor magnet strength and the correction amount instead of the relationship data between the field current and the correction amount. The correction amount calculation unit 28 stores the magnet strength calculated by the magnet strength calculation unit 21, the rotor magnet strength calculated by the rotor magnet strength calculation unit 23b, the d-axis current value obtained by the d-axis current acquisition unit 24, and the storage unit 27. A correction amount is calculated based on each relational data stored.

According to this embodiment, the following effects are obtained. A part of the rotor magnet magnetic flux and the d-axis magnetic flux Φd leaks from the rotor 60 and becomes disturbance magnetic flux, and the disturbance magnetic flux is included in the detected magnetic flux Φ. However, since the angle calculation unit 30 uses not only the detected magnetic flux Φ but also the rotor magnet strength and the d-axis current value to calculate the rotation angle, the disturbance magnetic flux is predicted based on the rotor magnet strength and the d-axis current value. can do. Based on the prediction, the influence of the disturbance magnetic flux contained in the detected magnetic flux Φ can be suppressed.

[Third Embodiment]
A rotation angle detection device 90 of the third embodiment will be described with reference to FIG. Regarding this embodiment, only the points that are different from the second embodiment will be described.

The rotation angle detection device 90 does not have the provisional angle calculator 13 . Also, the magnet strength calculation unit 21 and the rotor magnet strength calculation unit 23b are not provided because they are less affected by temperature. The storage unit 27 only stores relationship data between the d-axis current value and the correction amount, but does not store the relationship between the rotor magnet strength and the correction amount. The angle calculation unit 30 calculates the rotation angle of the rotor 60 based on the detected magnetic flux Φ detected by the detection unit 12, the d-axis current value obtained by the d-axis current acquisition unit 24, and the relational data stored in the storage unit 27. Calculate

According to this embodiment, the configuration of the rotation angle detection device 90 can be simplified by eliminating the provisional angle calculator 13, the magnet strength calculator 21, and the rotor magnet strength calculator 23b.

For example, the present embodiment can be modified as follows. In the first embodiment shown in FIG. 1 and the like, the provisional angle calculator 13 and the correction amount calculator 28 are eliminated, and the angle calculator 30 calculates the detected magnetic flux Φ, the magnet strength, the field current value, the d-axis current value, and each The rotation angle may be calculated based on the relationship data. Further, for example, in the first embodiment, the magnet strength calculator 21 may be omitted if the influence of temperature is not so problematic.

Further, for example, in each embodiment, instead of acquiring the d-axis current value from the rotating electric machine 95, the d-axis current acquisition unit 24 acquires each current value of the U-phase, V-phase, and W-phase, and from there acquires the d-axis current value. A current value may be calculated.

Further, for example, in each embodiment, the torque may be applied to the rotor 60 only by the d-axis magnetic flux Φd and the q-axis magnetic flux Φq without the field winding 65 and the rotor magnet instead.

Φ ... detected magnetic flux, Φe ... magnet magnetic flux, Φd ... d-axis magnetic flux, Φq ... q-axis magnetic flux, 11 ... magnet, 12 ... detector, 24 ... d-axis current acquisition section, 30 ... angle calculation section, 50 ... stator, 54 ... circuit, 60 ... rotor, 90 ... rotation angle detection device, 95 ... rotary electric machine.

Claims (5)

A rotatably mounted rotor (60), a rotor shaft (69) that rotates with the rotor, and a circuit (54) are provided, and by passing an electric current through the circuit, a predetermined amount of heat is generated in the rotor along the rotor shaft. and a stator (50) that generates a q-axis magnetic flux (Φq) orthogonal to the d-axis magnetic flux (Φd), and the d-axis magnetic flux leaks from the rotor ( A rotation angle detection device (90) for detecting the rotation angle of the rotor of 95),
a magnet (11) fixed to the tip of the rotor shaft and rotating together with the rotor;
a detection unit (12) for detecting, as a detection magnetic flux (Φ), a magnetic flux obtained by superimposing a magnetic flux (Φe), which is the magnetic flux of the magnet, and a leakage magnetic flux from the rotor, which is the d-axis magnetic flux;
a d-axis current acquisition unit (24) for acquiring a d-axis current value, which is the value of the d-axis current that is the component of the current flowing through the circuit that generates the d-axis magnetic flux;
an angle calculation unit (30) for calculating the rotation angle of the rotor based on the detected magnetic flux detected by the detection unit and the d-axis current value obtained by the d-axis current acquisition unit;
A rotation angle detection device having The rotor has a field winding (65) that generates a field magnetic flux (Φf), the detected magnetic flux includes leakage flux from the rotor of the field magnetic flux,
A field current acquisition unit (23) for acquiring a field current value that is the value of the field current that generates the field magnetic flux,
The angle calculator calculates the angle of the rotor based on the detected magnetic flux detected by the detector, the field current value obtained by the field current obtaining unit, and the d-axis current value obtained by the d-axis current obtaining unit. 2. The rotation angle detection device according to claim 1, which calculates a rotation angle. 3. The rotary electric machine has the field winding wound around the rotor shaft, and the field magnetic flux and the d-axis magnetic flux leak to the rotor shaft and are superimposed on the magnet magnetic flux. 3. The rotation angle detection device according to 2. A provisional angle calculation unit (13) for calculating a provisional rotation angle of the rotor based on the magnetic flux detected by the detection unit; and a correction amount based on the d-axis current value obtained by the d-axis current obtaining unit. a correction amount calculation unit (28) for calculating,
The angle calculation unit calculates the rotation angle of the rotor based on the provisional rotation angle calculated by the provisional angle calculation unit and the correction amount calculated by the correction amount calculation unit. 2. The rotation angle detection device according to item 1. A magnet strength calculation unit (21) for calculating a magnet strength, which is the magnitude of the magnet magnetic flux,
The angle calculation unit calculates the rotation angle of the rotor based on the detected magnetic flux detected by the detection unit, the magnet strength calculated by the magnet strength calculation unit, and the d-axis current value obtained by the d-axis current acquisition unit. The rotation angle detection device according to any one of claims 1 to 4, which calculates the rotation angle.

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