Rotation angle detection device, rotation angle detection method, and computer program

Abstract

To provide a rotation angle detection device capable of reducing cost.SOLUTION: A rotation angle detection device includes a motor including a drive magnet having a plurality of pole pairs, a rotor including a detection magnet having a plurality of pole pairs, a stator including a coil having a plurality of phases, and a magnetic detection unit that outputs a signal corresponding to a rotation position of the rotor, a storage unit that stores an electrical angle and a pole pair number of the detection magnet at a plurality of pull-in positions pulled in when any phase of the plurality of phases of the coil is energized, An absolute mechanical angle calculation unit that obtains an absolute mechanical angle of the rotor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotation angle detection device, a rotation angle detection method, a computer program, and the like that detect the angle of a rotating body. [Background technology]

[0002] 2. Description of the Related Art Conventionally, a technique for detecting the angle of a rotating body using a magnet having a plurality of pole pairs and a magnetic sensor is known.

[0003] For example, Patent Document 1 describes a rotation angle detection device that uses a ring-shaped magnet with multiple pole pairs and a magnetic sensor to detect the angle of a rotating body in order to accurately detect the rotation angle. The device also describes a configuration in which the ring magnet has a magnetized portion (strong magnetic portion) for detecting the origin, and calculates the absolute mechanical angle of the rotating body from the pole pair number assigned to each pole pair. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2023-122948 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in the conventional technology disclosed in the above-mentioned patent document, in order to provide a magnetized portion for detecting the origin, it is necessary to magnetize or shape the magnet so that the maximum values ​​of leakage magnetic flux in each pole pair become uneven, which poses a problem of increased manufacturing costs.

[0006] Therefore, one object of the present invention is to provide a rotation angle detection device that can be manufactured at low cost. [Means for solving the problem]

[0007] A rotation angle detection device according to one aspect of the present invention comprises: a rotor including a drive magnet having a plurality of pole pairs and a detection magnet having a plurality of pole pairs; a stator having a coil with multiple phases; a motor having a magnetic detection unit that outputs a signal corresponding to the rotational position of the rotor; a storage unit that stores electrical angles at a plurality of pull-in positions when a current is applied to any one of the plurality of phases of the coil, and pole pair numbers of the detection magnet; an absolute mechanical angle calculation unit that calculates an absolute mechanical angle of the rotor based on the electrical angle and the pole pair number stored in the storage unit; The present invention is characterized by having the following. [Effects of the Invention]

[0008] According to the present invention, a rotation angle detection device that can be reduced in cost can be realized. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a functional block diagram showing an example of a portion of a rotation angle detection device 100 according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view showing an example of the configuration of a motor 200 according to the present embodiment. [Figure 3] 1 is an external view showing an example of the configuration of a motor 200 according to the present embodiment. [Figure 4] 5 is a diagram showing an example of the magnetic flux densities detected by the first magnetic detection unit 211a and the second magnetic detection unit 211b in this embodiment. FIG. [Figure 5] 5A and 5B are diagrams illustrating examples of current conduction patterns in the present embodiment. [Figure 6] 5A and 5B are diagrams illustrating examples of detected electrical angles and pull-in positions in the present embodiment. [Figure 7] 10 is a flowchart illustrating an example of the flow of a data storage process in the present embodiment. [Figure 8A] 10 is a flowchart illustrating an example of the flow of an absolute angle calculation step in the present embodiment. [Figure 8B] 8B is a flowchart illustrating a continuation of FIG. 8A. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the present invention is not limited to the following embodiments. In each drawing, the same members or elements are designated by the same reference numerals, and duplicate descriptions will be omitted or simplified.

[0011] Fig. 1 is a functional block diagram showing an example of a portion of a rotation angle detection device 100 according to an embodiment of the present invention. Note that some of the functional blocks shown in Fig. 1 are realized by causing a CPU or the like serving as a computer (not shown) included in the rotation angle detection device 100 to execute a computer program stored in a memory (not shown) serving as a storage medium.

[0012] However, some or all of these functions may be implemented by hardware. Examples of hardware that can be used include dedicated circuits (ASICs) and processors (reconfigurable processors, DSPs). Furthermore, the functional blocks shown in Figure 1 do not have to be built into the same housing, and may be configured as separate devices connected to each other via signal paths.

[0013] The rotation angle detection device 100 of this embodiment includes a motor 200 and a controller 300, and the controller 300 includes an angle calculation unit 310 and a motor control unit 320. Note that in this embodiment, the controller 300 and the motor 200 are separate entities, but part or all of the controller 300 may be integrated with the motor 200.

[0014] The angle calculation unit 310 includes an A / D conversion unit 311, an electrical angle calculation unit 312, a storage unit 313, and an absolute mechanical angle calculation unit 314. The storage unit 313 is a medium that can be read by the electrical angle calculation unit 312 and the absolute mechanical angle calculation unit 314, and stores table values ​​and a control program, which will be described later.

[0015] The motor control unit 320 includes a motor control unit 321 and a motor drive unit 322. The motor 200 also includes a stator 210, a rotor 220, a first magnetic detection unit 211a, and a second magnetic detection unit 211b.

[0016] Fig. 2 is a cross-sectional view showing an example of the configuration of the motor 200 in this embodiment, and Fig. 3 is an external view showing an example of the configuration of the motor 200 in this embodiment. Note that the motor 200 in this embodiment employs an outer-type three-phase brushless motor, but may also be an inner-type.

[0017] Stator 210 is composed of base 212, electronic circuit board 213, housing 214, bearings 215a and 215b, coil 216, and core 217. Base 212 has screw holes (not shown) that allow it to be fixed to, for example, a semiconductor manufacturing device (not shown). Housing 214 has a fitting portion formed on its outer circumferential surface to engage with base 212. Housing 214 is press-fitted into base 212, but may also be fixed by adhesive, crimping, or welding.

[0018] Engagement portions for bearings 215a and 215b are formed on the inner circumferential surface of housing 214. Bearings 215a and 215b are bonded or press-fitted into housing 214 to support rotor 220 so as to be rotatable.

[0019] Bearings 215a and 215b are rolling bearings, which allow for smooth rotation. Core 217 is formed by laminating multiple soft magnetic steel plates, and has multiple slots extending in the radial direction. A fitting portion for fitting with housing 214 is formed on the inner peripheral surface.

[0020] Core 217 is adhered, press-fitted, or crimped to housing 214. Furthermore, coil 216 is wound around the slot of core 217, and generates a magnetic force when a current is passed through coil 216.

[0021] In this embodiment, the core 217 has 12 slots, but in the case of a three-phase brushless motor, the number of slots is set to an optimal number that is a multiple of 3, taking into account the size, generated torque, and cogging torque. The coil 216 has multiple phases (for example, three phases: U phase, V phase, and W phase).

[0022] The rotor 220 includes a yoke 221, a drive magnet 222, a rotating shaft 223, and a detection magnet 224. The yoke 221 has an engaging portion formed on its inner circumferential surface for engagement with the drive magnet 222. The drive magnet 222 is ring-shaped, and its outer circumferential surface is bonded to the yoke 221, so that it rotates integrally with the yoke 221. The yoke 221 is a magnetic body, and forms a magnetic circuit together with the drive magnet 222.

[0023] The yoke 221 is provided with a fitting portion for the rotating shaft 223, and by fixing the rotating shaft 223 by crimping, the yoke 221 rotates integrally with the rotating shaft 223. The fixing method may be press-fitting, bonding, or welding, and the yoke 221 and the rotating shaft 223 may be formed integrally.

[0024] The drive magnet 222 has multiple pole pairs and is polarized and magnetized as shown in Fig. 3 in order to generate a repulsive or attractive force against the magnetic force generated by the rotor 220. In this embodiment, the number of magnetized poles is 14, and the number of pole pairs is 7. The number of poles is set to an optimal number taking into consideration the size, generated torque, and cogging torque.

[0025] The detection magnet 224 is ring-shaped, has an engaging portion formed on its inner circumferential surface for engagement with the rotating shaft 223, is bonded to the rotating shaft 223, and rotates integrally with the rotating shaft 223. The detection magnet 224 is polarized and magnetized as shown in FIG. 3, and has multiple pole pairs.

[0026] It is desirable that the number of pole pairs of the detection magnet 224 is different from the number of pole pairs of the drive magnet 222. It is also desirable that the numbers of pole pairs are prime numbers (a common divisor of 1). In this embodiment, the number of pole pairs of the drive magnet 222 is 7. On the other hand, the number of poles of the detection magnet 224 is 8, and the number of pole pairs is 4. The greater the number of pole pairs, the better the accuracy and resolution.

[0027] Next, the configuration of the electronic circuit board 213 will be described. The electronic circuit board 213 has a magnetic detection unit 211 that outputs a signal according to the rotational position of the rotor. It also has a connection unit (not shown) that connects to the controller 300. In this embodiment, the magnetic detection unit 211 is made up of a first magnetic detection unit 211a and a second magnetic detection unit 211b.

[0028] The first magnetic detection unit 211a and the second magnetic detection unit 211b are, for example, Hall elements, which detect leakage magnetic flux that penetrates perpendicularly to the mounting surface of the base 212 and output a voltage corresponding to the leakage magnetic flux. The first magnetic detection unit 211a and the second magnetic detection unit 211b are arranged at positions facing the detection magnet 224 with a predetermined gap between them, detect the leakage magnetic flux that changes in accordance with the rotation of the rotor 220, and output a voltage corresponding to the leakage magnetic flux.

[0029] The second magnetic detection unit 211b is attached at a position that is 90 degrees out of phase with the first magnetic detection unit 211a in the detection electrical angle of the detection magnet 224. In this embodiment, a detection electrical angle of 360 degrees corresponds to a mechanical angle of 90 degrees. In other words, a detection electrical angle of 90 degrees corresponds to a mechanical angle of 22.5 degrees. The number of magnetic detection units 211 is not limited to two, and three or more sensors may be used.

[0030] Moreover, the magnetic detection unit 211 may be disposed in the radial direction of the detection magnet 224. Furthermore, a single package may contain multiple magnetic sensors, an A / D conversion unit 311 and an angle calculation unit 310 (described later), and be configured as an encoder IC that outputs angle information.

[0031] FIG. 4 is a diagram showing an example of the detected magnetic flux density by the first magnetic detection unit 211a and the second magnetic detection unit 211b in this embodiment. Below, a method for detecting the rotation angle of the rotor 220 by the first magnetic detection unit 211a and the second magnetic detection unit 211b will be described with reference to FIG. 4.

[0032] 4, the vertical axis represents the magnetic flux density detected by the first magnetic detection unit 211a and the second magnetic detection unit 211b, with a positive value for the N pole and a negative value for the S pole. One curve represents the magnetic flux density detected by the first magnetic detection unit 211a, and the other curve represents the magnetic flux density detected by the second magnetic detection unit 211b.

[0033] 4, when the rotation angle is 0 degrees, the detected magnetic flux density of the first magnetic detection unit 211a is 0. The detected magnetic flux density of the second magnetic detection unit 211b is out of phase with the detected magnetic flux density of the first magnetic detection unit 211a by 90 degrees in detected electrical angle.

[0034] The voltages output from the first magnetic detection unit 211a and the second magnetic detection unit 211b are input to an A / D conversion unit 311 and converted into digital signals. The converted signals are input to an electrical angle calculation unit 312 and converted into a detected electrical angle. The detected electrical angle is calculated by calculating an arctangent value based on the output values ​​of the first magnetic detection unit 211a and the second magnetic detection unit 211b.

[0035] The detection magnet 224 used in this embodiment has four pole pairs, and since the detected electrical angle rotates four times per mechanical angle rotation, a pole pair number is set for each rotation of the detected electrical angle in the data storage step described later, as shown in Fig. 4. The pole pair numbers set in this embodiment are MP1 to MP4.

[0036] Next, we will explain the retraction operation of motor 200. Motor 200 is a three-phase brushless motor, and the phases of coil 216 are U-phase, V-phase, and W-phase. Rotor 220 can be rotated by appropriately changing the pattern of the energized phases.

[0037] In other words, if the energized phase is not switched, the rotor 220 will remain in its current position. For example, if energization continues from the U phase to the V phase, the motor 200 will be locked. This is called a pull-in operation.

[0038] The retracted position is determined by the positional relationship between core 217 and drive magnet 222. Motor control unit 320 includes a motor control unit 321 and a motor drive unit 322. Motor drive unit 322 is an inverter circuit and has, for example, six switching elements (not shown).

[0039] Three-phase AC power is generated by switching these switching elements based on switching commands generated by the motor control unit 321. The generated AC power is supplied to the coils 216 for each of the three phases.

[0040] FIG. 5 is a diagram showing an example of a current conduction pattern in this embodiment, showing a current conduction pattern when current is conducted between two of the phases. Current flows from the high side (Hi) to the low side (Low). There are six current conduction patterns (draw-in patterns), and by switching the current conduction in the order of the current conduction patterns shown in FIG. 5, the rotor 220 rotates 360 degrees in drive electrical angle.

[0041] That is, there is only one position for pull-in over a drive electrical angle of 360 degrees per current pattern. In this embodiment, current is passed between two phases to perform the pull-in operation, but the number of phases to which current is passed is not limited to two, and may be three or more phases, or may be one phase.

[0042] 6 is a diagram showing an example of detected electrical angles and pull-in positions in this embodiment. The drive magnet 222 used in this embodiment has seven pole pairs, so the drive electrical angle rotates seven times per mechanical angle rotation. In other words, there are seven positions per mechanical angle rotation that are pulled in by each current conduction pattern (pull-in pattern).

[0043] 6, circles UV1 to UV7 indicate examples of positions where current is drawn when a current flows from the U phase to the V phase. Squares VW1 to VW7 indicate examples of positions where current is drawn when a current flows from the V phase to the W phase. Between UV1 and VW1, there is a difference of 68 degrees in detected electrical angle and approximately 17.14 degrees in mechanical angle.

[0044] Since the drive electrical angle is seven revolutions and the detection electrical angle is four revolutions per mechanical angle revolution, there are one or two pull-in positions per detection electrical angle revolution. Furthermore, if the numbers of pole pairs of the drive magnet 222 and the detection magnet 224 are both prime numbers (the common divisor is 1), then in an ideal state, the detection electrical angles at each pull-in position will never match.

[0045] Next, the data storage process will be described. Fig. 7 is a flowchart showing an example of the flow of the data storage process in this embodiment. Note that the operation of each step in the flowchart in Fig. 7 is performed sequentially by a CPU or the like serving as a computer within the rotation angle detection device 100 executing a computer program stored in memory.

[0046] 7 is a process of storing the retraction positions, the detected electrical angles at those positions, and the pole pair numbers of the detection magnet 224 as table values ​​in the storage unit 313. In other words, this is a storage process of storing in the storage unit the electrical angles and pole pair numbers of the detection magnet at multiple retraction positions that are retracted when current is applied to any one of the multiple phases of the coil.

[0047] In addition, in the absolute angle calculation step described in Fig. 8, the absolute mechanical angle is calculated using the table values ​​stored in the data storage step shown in Fig. 7. That is, in the processing flow of Fig. 8, the absolute mechanical angle calculation unit 314 executes the absolute mechanical angle calculation step of determining the absolute mechanical angle of the rotor based on the electrical angle and pole pair number stored in the storage unit 313. Note that the rotation angle detection method of this embodiment is realized by using the processing flows of Figs. 7 and 8.

[0048] In this embodiment, the detected electrical angle and pole pair number for all six pull-in patterns are stored, but only a portion of the pull-in patterns may be stored. Furthermore, although the rotation direction of the rotor 220 in this embodiment is the direction in which the detected electrical angle shifts in the positive direction, it may also be the direction in which the detected electrical angle shifts in the negative direction.

[0049] First, in step S401, the pole pair number is initialized, and in step S402, the pull-in operation is started using pull-in pattern N (N is an integer between 1 and 7). Then, in step S403, the detected electrical angle at the pulled-in position is obtained. Note that the pull-in operation in step S402 continues until step S403 is completed.

[0050] In step S404, it is determined whether the condition for updating the pole pair number is met. That is, the detected electrical angle obtained in step S403 is compared with the detected electrical angle obtained in the previous loop, and if the detected electrical angle obtained in step S403 is smaller, it is determined that updating is necessary.

[0051] If the determination in step S404 is Yes, the process proceeds to step S405, where the pole pair number is updated by adding 1. If the determination in step S404 is No, the process proceeds to step S406.

[0052] However, this determination condition is an example when the detected electrical angle changes in the positive direction, and when the detected electrical angle changes in the negative direction, it is determined that updating is necessary (Yes in step S404) if the detected electrical angle acquired in step S403 is larger. Note that, when the loop is the first time, it is determined in step S404 that updating is not necessary, and the pole pair number is not updated.

[0053] In step S406, the acquired detected electrical angle and pole pair number are recorded in the storage unit 313 as table values.

[0054] Next, in step S407, it is determined whether the mechanical angle has made one revolution. That is, it is determined whether the mechanical angle has made one revolution based on the number of pole pairs, the pull-in pattern, and the number of loops of the drive magnet 222. Specifically, if the number of pole pairs of the drive magnet 222 is 7 and the pull-in operation pattern is 6, it is determined that the mechanical angle has made one revolution when the number of loops is equal to 42, which is the product of these factors.

[0055] If it is determined in step S407 that the mechanical angle has completed one revolution, the process flow in Fig. 7 ends. If it is determined that the mechanical angle has not completed one revolution, the process proceeds to step S408, where the pull-in pattern is updated, and the process proceeds to step S402. Note that in this embodiment, data for one revolution of the mechanical angle is stored, but only a portion of the mechanical angle may be stored.

[0056] Next, with reference to FIGS. 8A and 8B, an absolute angle calculation process for calculating an absolute mechanical angle using the retraction position, the detected electrical angle at that position, and the pole pair number of the detection magnet 224, which are stored as table values ​​in the storage unit 313 in the flow of FIG. 7, will be described.

[0057] Fig. 8A is a flowchart showing an example of the flow of the absolute angle calculation process in this embodiment, and Fig. 8B is a flowchart that follows Fig. 8A. Note that the operations of the steps in the flowcharts of Fig. 8A and Fig. 8B are performed sequentially by a CPU or the like serving as a computer within rotation angle detection device 100 executing a computer program stored in memory.

[0058] The absolute angle calculation process is divided into an initialization operation in steps S501 to S510, which will be described later, and an absolute mechanical angle calculation operation from step S513 onwards.

[0059] The initialization operation is an operation for obtaining the pole pair number at the pulled-in position by comparing the electrical angle detected in the pull-in process with the table value obtained in the data storage process, which will be described later.

[0060] It should be noted that if the rotor 220 is being held by some kind of external force, the correct pole pair number cannot be determined during the retraction process. Therefore, it is desirable to perform the retraction process two or more times to determine whether there is holding by an external force. However, if there is no possibility of holding by an external force, the retraction process may be performed only once.

[0061] When the power of the controller 300 is turned on, the first retraction process starts in step S501. In the first retraction process, the rotor 220 is retracted according to a preset retraction operation pattern 1. The retraction operation continues until step S502 is completed.

[0062] Pull-in operation pattern 1 and pull-in operation pattern 2, which will be described later, are included in the pull-in operation patterns used when storing the table values ​​in the data storage step of Fig. 7. That is, the same pull-in operation pattern as the two pull-in operation patterns in Fig. 8A is executed in advance in step S402 of Fig. 7.

[0063] In this embodiment, pull-in operation pattern 1 is energization from U phase to V phase, and pull-in operation pattern 2 is energization from V phase to W phase. When energization is switched from pull-in operation pattern 1 to pull-in operation pattern 2, the detected electrical angle is shifted in the positive direction, but the detected electrical angle may be shifted in the negative direction.

[0064] The current pattern may be set as appropriate, but it is desirable to apply current to different phases because if current is applied to the same phase during the first and second retraction processes, the rotor 220 will not rotate. That is, in this embodiment, there are at least two patterns for the phases to which current is applied during retraction, and retraction is performed at least in two locations.

[0065] In step S502, the detected electrical angle is obtained when the rotor 220 is pulled in. In step S503, it is determined whether or not a value that satisfies the criteria is in the table.

[0066] That is, the pole pair number is determined by comparing the detected electrical angle acquired in step S502 with the table value stored in the storage unit 313. Specifically, a determination region is set for the detected electrical angle stored in the storage unit 313, taking into consideration mechanical errors, errors due to detection, and the like.

[0067] For example, in the case of UV1 shown in Figure 6, the ideal detection electrical angle is 0 degrees, but taking into account the above-mentioned errors, etc., the judgment region is set to 350 degrees to 10 degrees. The width of the judgment region can be set to an appropriate optimal value as long as it does not overlap with the judgment regions of adjacent pull-in positions.

[0068] It is determined whether the detected electrical angle obtained in step S502 is within the determination range of the table values ​​stored in storage unit 313, and if there is a value in the table that satisfies the determination condition (Yes in step S503), the process proceeds to step S505. If there is no data in the table that satisfies the determination condition, the process proceeds to step S504, where it is determined to be an error, and the process flow in FIGS. 8A and 8B ends.

[0069] In step S505, the pole pair number at the detected electrical angle that satisfies the determination condition in step S503 is obtained from the table. Next, in step S506, the detected electrical angle during the second pull-in process is calculated. That is, the detected electrical angle in pull-in operation pattern 2 is calculated from the electrical angle detected in step S502.

[0070] Specifically, as mentioned above, there is a difference of 68 degrees in the detected electrical angle between UV1 and VW1, so for example, if the detected electrical angle in step S502 is 0 degrees, the value obtained by adding 68 degrees becomes the detected electrical angle in pull-in operation pattern 2 (second pull-in process).

[0071] In step S507, the second retraction process is performed. In the second retraction process, the retraction operation is performed according to preset retraction operation pattern 2. The retraction operation continues until step S508 is completed.

[0072] In step S508, the detected electrical angle at the retracted position of rotor 220 is acquired. Next, in step S509, it is determined whether the detected electrical angle is correct. That is, the detected electrical angle acquired in step S508 is compared with the detected electrical angle calculated in step S506, and if it is within a predetermined determination range, the determination is Yes, the initialization operation is completed, and the process proceeds to step S511.

[0073] The determination region in step S509 is set with consideration given to mechanical errors, detection errors, etc. for the detected electrical angle calculated in step S506. For example, in the case of VW1 shown in Fig. 6, the ideal detected electrical angle is 68 degrees, but taking the above errors, etc. into consideration, if the determination region is within a region of, for example, 58 degrees to 78 degrees, the determination is made as "Yes."

[0074] The width of this determination region is set to an appropriate optimum value within a range that does not overlap with the determination regions of adjacent pull-in positions. As described above, in step S509, it is determined whether the detected electrical angle obtained in step S508 is included in the above determination region. If it is determined that the detected electrical angle is included, the initialization operation is completed and the process proceeds to step S511.

[0075] If the determination in step S509 is No, the process proceeds to step S510, where it is determined to be an error, and the processing flow of FIGS. 8A and 8B ends.

[0076] In step S511, it is determined whether the conditions for updating the pole pair number are met. That is, it is determined whether the pole pair number needs to be updated, and if it is, the process proceeds to step S512, where the pole pair number is updated. If it is determined in step S511 that it is not necessary (No), the process proceeds to step S513.

[0077] Specifically, the determination in step S511 is made by comparing the detected electrical angle acquired in step S502 with the detected electrical angle acquired in step S508, and if the detected electrical angle acquired in step S508 is smaller, it is determined that an update is necessary.

[0078] However, this determination condition is that the detected electrical angle changes in the positive direction. In the case of a change in the negative direction, it is determined that updating is necessary if the detected electrical angle acquired in step S508 is larger.

[0079] In step S513, the absolute mechanical angle calculation unit 314 calculates the absolute mechanical angle. That is, for example, the absolute mechanical angle of the rotor 220 is calculated by the following equation (1). Note that the number of pole pairs in equation (1) is the number of pole pairs of the drive magnet 222. Absolute mechanical angle = detected electrical angle / number of pole pairs + (360 degrees × (pole pair number - 1) / number of pole pairs) (1)

[0080] Next, in step S514, the absolute mechanical angle calculation unit 314 outputs the absolute mechanical angle to the motor control unit 321. The motor control unit 321 uses the absolute mechanical angle to calculate a switching signal for the motor drive unit 322 and controls the operation of the motor 200.

[0081] Thereafter, in step S515, it is determined whether or not the operation has ended. That is, if a command to end the operation is issued from controller 300, the processing flow of FIGS. 8A and 8B ends. If a command to end the operation has not been issued, the process proceeds to step S516, where the detected electrical angle is acquired. Furthermore, in step S517, it is determined whether or not the update condition for the pole pair number is met. That is, it is determined whether or not the pole pair number should be updated.

[0082] For example, if the detected electrical angle acquired in step S516 changes from 360 degrees to 0 degrees, or from 0 degrees to 360 degrees, it is determined that the update condition for the pole pair number is satisfied. If it is determined that updating is not necessary, the process proceeds to step S513.

[0083] If it is determined in step S517 that the update condition is met, the process proceeds to step S518, where the pole pair number is updated. That is, if the determination in step S517 is Yes, for example, due to a change from 360 degrees to 0 degrees, the pole pair number is incremented by 1 in step S518. However, if the pole pair number is the same as the number of pole pairs of the detection magnet 224, the pole pair number is incremented by 1 and then the number of pole pairs is decremented.

[0084] On the other hand, if the determination in step S517 is Yes due to a change from 0 degrees to 360 degrees, 1 is subtracted from the pole pair number in step S518. However, if the pole pair number is 1, a value obtained by subtracting 1 from the number of pole pairs of the detection magnet 224 is added to the pole pair number. After updating of the pole pair number in step S518 is completed, the process proceeds to step S513.

[0085] As described above, in the processing flow shown in FIG. 8, pull-in is performed by energizing one of the multiple phases of the coil, and the electrical angle at the time of pull-in is compared with the electrical angle stored in the storage unit to calculate the absolute mechanical angle.

[0086] As described above, according to this embodiment, even when a detection magnet 224 having multiple pole pairs is used, the controller 300 can detect the absolute mechanical angle of the rotor 220 with high accuracy. Furthermore, the detection magnet 224 does not require special magnetization or a special shape. This allows the cost of the rotation angle detection device 100 to be reduced.

[0087] The present invention has been described above in detail based on its preferred embodiments, but the present invention is not limited to the above embodiments, and various modifications and combinations of the above embodiments are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0088] The present invention also includes those that realize the functions of the above embodiments using, for example, at least one processor such as a CPU, memory, or circuit (for example, ASIC). Also, multiple processors may be used to perform distributed processing.

[0089] In order to realize some or all of the control in the above-described embodiments, a computer program that realizes the functions of the above-described embodiments may be supplied to a rotation angle detection device or the like via a network or various storage media. Then, a computer (or a CPU, MPU, or the like) in the rotation angle detection device or the like may read and execute the program. In this case, the program and the storage medium storing the program constitute the present invention. The present invention also includes the following combinations.

[0090] (Configuration 1) A rotation angle detection device characterized by comprising: a motor having a drive magnet having a plurality of pole pairs, a rotor equipped with a detection magnet having a plurality of pole pairs, a stator having a coil with a plurality of phases, and a magnetic detection unit that outputs a signal according to the rotational position of the rotor; a memory unit that stores the electrical angles and pole pair numbers of the detection magnet at a plurality of pull-in positions when current is applied to any of the plurality of phases of the coil; and an absolute mechanical angle calculation unit that calculates the absolute mechanical angle of the rotor based on the electrical angles and the pole pair numbers stored in the memory unit.

[0091] (Configuration 2) The rotation angle detection device according to configuration 1, wherein the coil has three phases.

[0092] (Configuration 3) The rotation angle detection device according to configuration 1 or 2, wherein the magnetic detection unit includes a first magnetic detection unit and a second magnetic detection unit arranged in positions facing the detection magnet.

[0093] (Configuration 4) The rotation angle detection device according to any one of configurations 1 to 3, wherein the drive magnet and the detection magnet have different numbers of pole pairs.

[0094] (Configuration 5) The rotation angle detection device according to any one of configurations 1 to 4, wherein the common divisor of the number of pole pairs of the drive magnet and the detection magnet is one.

[0095] (Configuration 6) The rotation angle detection device according to any one of configurations 1 to 5, characterized in that pull-in is performed by energizing one of the multiple phases of the coil, and the electrical angle at the time of the pull-in is compared with the electrical angle stored in the memory unit to calculate the absolute mechanical angle.

[0096] (Configuration 7) The rotation angle detection device according to configuration 6, wherein the retraction is performed at least at two locations.

[0097] (Configuration 8) The rotation angle detection device according to any one of configurations 1 to 7, characterized in that there are at least two patterns of phases to be energized during the pull-in.

[0098] (Method) A rotation angle detection method using a motor having a stator including a rotor equipped with a drive magnet having multiple pole pairs, a detection magnet having multiple pole pairs, a coil having multiple phases, and a magnetic detection unit that outputs a signal according to the rotational position of the rotor, the method comprising: a storage step of storing the electrical angles and pole pair numbers of the detection magnet at multiple pull-in positions when current is applied to any of the multiple phases of the coil; and an absolute mechanical angle calculation step of calculating the absolute mechanical angle of the rotor based on the electrical angles and pole pair numbers stored in the storage step.

[0099] (Program) A computer program for controlling each part of the rotation angle detection device according to any one of configurations 1 to 8 by a computer. [Explanation of symbols]

[0100] 100: Rotation angle detection device 200: Motor 211: Magnetic detection unit 211a: First magnetic detection unit 211b: Second magnetic detection unit 213: Electronic circuit board 216: Coil 217: Core 220:Rotor 222: Drive magnet 224: Detection magnet 312: Electrical angle calculation unit 314: Absolute mechanical angle calculation unit MP1, MP2, MP3, MP4: Pole pair numbers

Claims

1. a rotor including a drive magnet having a plurality of pole pairs and a detection magnet having a plurality of pole pairs; a stator having a coil with multiple phases; a motor having a magnetic detection unit that outputs a signal corresponding to the rotational position of the rotor; a storage unit that stores electrical angles at a plurality of pull-in positions when a current is applied to any one of the plurality of phases of the coil, and pole pair numbers of the detection magnet; an absolute mechanical angle calculation unit that calculates an absolute mechanical angle of the rotor based on the electrical angle and the pole pair number stored in the storage unit; A rotation angle detection device comprising:

2. 2. The rotation angle detection device according to claim 1, wherein the coil has three phases.

3. 2. The rotation angle detection device according to claim 1, wherein the magnetic detection unit includes a first magnetic detection unit and a second magnetic detection unit that are disposed in positions facing the detection magnet.

4. 2. The rotation angle detection device according to claim 1, wherein the number of pole pairs of the drive magnet and the detection magnet are different.

5. 2. The rotation angle detection device according to claim 1, wherein a common divisor of the number of pole pairs of the drive magnet and the detection magnet is 1.

6. 2. The rotation angle detection device according to claim 1, wherein the pull-in is performed by energizing one of the plurality of phases of the coil, and the absolute mechanical angle is calculated by comparing the electrical angle at the time of the pull-in with the electrical angle stored in the memory unit.

7. 7. The rotation angle detection device according to claim 6, wherein the retraction is performed at least at two locations.

8. 2. The rotation angle detection device according to claim 1, wherein the device has at least two patterns of phases to be energized during the pull-in.

9. a rotor including a drive magnet having a plurality of pole pairs and a detection magnet having a plurality of pole pairs; A rotation angle detection method using a motor having a stator including a coil having a plurality of phases and a magnetic detection unit that outputs a signal according to a rotation position of the rotor, the method comprising: a storage step of storing the electrical angles at a plurality of pull-in positions when a current is applied to any one of the plurality of phases of the coil and the pole pair numbers of the detection magnet; an absolute mechanical angle calculation step of calculating an absolute mechanical angle of the rotor based on the electrical angle and the pole pair number stored in the storage step; A rotation angle detection method comprising:

10. A computer program for controlling each part of the rotation angle detection device according to any one of claims 1 to 8 by a computer.

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