Rotation detection device

Abstract

To provide a rotation detecting device capable of calculating angle information with relatively little delay.SOLUTION: A rotation angle sensor 30 includes at least three detecting elements 31 to 33 for detecting a change in a physical quantity in accordance with the rotational position of a motor. The rotation angle sensor 30 outputs rotation angle information relating to the number of times of rotation TC of the motor corresponding to a detected value of at least one detecting element. The rotation angle sensor 30 outputs the rotation angle information relating to a rotation angle of the motor corresponding to the detected value of each of the detecting elements 31 to 33 as at least one analog signal and at least one digital signal. A control section 60 includes an absolute angle calculating section 65 and an abnormality determining section 68. The absolute angle calculating section 68 outputs, to a control arithmetic section 69, an absolute angle calculated using a value determined as being correct, out of an analog rotation angle θm_a, which is a rotation angle based on the analog signal, and a digital rotation angle θm_d, which is a rotation angle based on the digital signal.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a rotation detection device.

Background Art

[0002] Conventionally, a device that generates rotation angle information of a motor based on the detection value of a detection element has been known. For example, in Patent Document 1, an angle calculation unit and a rotation speed calculation unit are provided in a sensor unit, and an output signal is output to a microcomputer by digital communication such as SPI communication.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In Patent Document 1, since information related to the rotation angle and the rotation speed is transmitted to a microcomputer by digital communication, a calculation delay due to digital calculation and output occurs.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide a rotation detection device capable of calculating angle information with relatively little delay.

Means for Solving the Problems

[0006] The According to the first aspect rotation detection device of the present invention includes a rotation angle sensor (30) and a control unit (60). The rotation angle sensor includes at least three sensor elements (31 to 33) that detect a change in a physical quantity corresponding to the rotation position of a detection target (80). have The rotation angle sensor outputs, as an analog signal, the detection value of at least one detection element different from the detection element that outputs an analog signal according to the detection value of at least one detection element. Ta A analog signal The signal is output from the analog signal output terminals (328, 383). The rotation angle sensor detects the value the detection value of at least one detection element different from the detection element that outputs an analog signal according to the detection value of at least one detection element The system includes a signal processing unit (35) that calculates rotation angle information and rotation count information using a digital signal, and outputs the calculated rotation angle information and rotation count information as digital signals from a digital signal output terminal (381). .

[0007] The control unit is Related to the rotation angle of the object being detected Rotation angle information and Related to the number of rotations to be detected The system includes an absolute angle calculation unit (65) that calculates the absolute angle, which is the amount of rotation from a reference position, using rotation count information, and an abnormality determination unit (69) that performs abnormality detection of the rotation angle information. The control unit has an angle calculation unit (64) that calculates the rotation angle based on an analog signal. Here, the rotation angle information output to the control unit as a digital signal is called the digital rotation angle, and the rotation angle information calculated using the analog signal is called the analog rotation angle. The absolute angle calculation unit is ,a Analog rotation angle is The absolute angle calculated using the digital rotation angle value determined to be normal is output to the control calculation unit (69). The absolute angle calculation unit, when the analog rotation angle is normal, calculates the absolute angle based on the rotation count information included in the digital signal and the analog rotation angle, at least in the first calculation, and in subsequent calculations, prioritizes outputting the absolute angle calculated using the analog rotation angle to the control calculation unit. In the second and third aspects of the present invention, the rotation detection device comprises a rotation angle sensor (30) and a control unit (60). The rotation angle sensor has at least three sensor elements (31-33) that detect changes in a physical quantity corresponding to the rotation position of the object to be detected (80), and outputs rotation count information relating to the number of rotations of the object to be detected according to the detected value of at least one detection element. The rotation angle sensor also outputs a signal corresponding to the detected value of at least one detection element as an analog signal, and outputs rotation angle information corresponding to the detected value of at least one detection element different from the detection element that outputs the detected value as an analog signal as a digital signal. The control unit includes an absolute angle calculation unit (65) that calculates the absolute angle, which is the amount of rotation from a reference position, using rotation angle information and rotation count information, and an abnormality determination unit (69) that determines abnormalities in the rotation angle information. The absolute angle calculation unit outputs the calculated absolute angle to the control calculation unit (69) using the value determined to be normal, which is either the analog rotation angle, which is rotation angle information based on an analog signal, or the digital rotation angle, which is rotation angle information based on a digital signal. In the second embodiment, the absolute angle calculation unit calculates the absolute angle using the rotation count information and the analog rotation angle in the first calculation when the analog rotation angle is normal, and calculates the absolute angle using the previous value of the absolute angle and the analog rotation angle in the second and subsequent calculations. At the comparison timing, the absolute angle calculation unit performs an absolute angle calculation using the analog rotation angle or digital rotation angle and the rotation count information, and compares it with the absolute angle calculated using the previous value. In the third embodiment, the absolute angle calculation unit, in the first calculation, sets the absolute angle calculated using the rotation count information and the analog rotation angle as the analog absolute angle, and the absolute angle calculated using the rotation count information and the digital rotation angle as the digital absolute angle. In the second and subsequent calculations, sets the value calculated using the previous absolute angle value and the analog rotation angle as the analog absolute angle, and the value calculated using the previous absolute angle value and the digital rotation angle as the digital absolute angle. If the analog rotation angle is normal, it outputs the analog absolute angle to the control calculation unit, and if all analog rotation angles are abnormal, it outputs the digital absolute angle to the control calculation unit. At the comparison timing, the absolute angle calculation unit performs an absolute angle calculation using the analog rotation angle or digital rotation angle and the rotation count information, and compares it with the absolute angle calculated using the previous value. By outputting at least some of the detected values ​​as analog signals from the rotation angle sensor to the control unit, angle calculations can be performed with relatively little delay. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic diagram of the steering system according to the first embodiment. [Figure 2] This is a block diagram showing a rotation detection device according to the first embodiment. [Figure 3] This is an explanatory diagram illustrating the absolute angle according to the first embodiment. [Figure 4] This is a time chart illustrating the digital and analog signals according to the first embodiment. [Figure 5] This is a flowchart illustrating the angle calculation process according to the first embodiment. [Figure 6] This is a flowchart illustrating the angle calculation process according to the second embodiment. [Figure 7] This is a flowchart illustrating the angle calculation process according to the third embodiment. [Figure 8] This is a flowchart illustrating the angle calculation process according to the fourth embodiment. [Figure 9] It is a flowchart for explaining the angle calculation process according to the fifth embodiment.

Embodiments for Carrying Out the Invention

[0009] Hereinafter, the rotation detection device according to the present invention will be described based on the drawings. Hereinafter, in a plurality of embodiments, substantially the same configurations are denoted by the same reference numerals and the description thereof is omitted.

[0010] (First Embodiment) The first embodiment is shown in FIGS. 1 to 5. As shown in FIGS. 1 and 2, the rotation detection device 1 includes a rotation angle sensor 30 and a control unit 60, and is applied to an electric power steering device 8. FIG. 1 shows the configuration of a steering system 90 including the electric power steering device 8. The steering system 90 includes a steering wheel 91 as a steering member, a steering shaft 92, a pinion gear 96, a rack shaft 97, wheels 98, and the electric power steering device 8 and the like.

[0011] The steering wheel 91 is connected to the steering shaft 92. A torque sensor 94 for detecting a steering torque is provided on the steering shaft 92. A pinion gear 96 is provided at the tip of the steering shaft 92. The pinion gear 96 meshes with the rack shaft 97. A pair of wheels 98 are connected to both ends of the rack shaft 97 via tie rods or the like.

[0012] When a driver rotates the steering wheel 91, the steering shaft 92 connected to the steering wheel 91 rotates. The rotational movement of the steering shaft 92 is converted into a linear movement of the rack shaft 97 by the pinion gear 96. The pair of wheels 98 are steered at an angle corresponding to the displacement amount of the rack shaft 97.

[0013] The electric power steering system 8 includes a drive unit 10 having an ECU 20 and a motor 80, and a reduction gear 89, etc., which is a power transmission unit that reduces the rotation of the motor 80 and transmits it to the steering shaft 92. In other words, the electric power steering system 8 of this embodiment is a so-called "column assist type," and the steering shaft 92 can be said to be the drive target. It may also be a so-called "rack assist type" that transmits the rotation of the motor 80 to the rack shaft 97.

[0014] Motor 80 outputs part or all of the torque required for steering, and is driven by power supplied from a battery (not shown), causing the reduction gear 89 to rotate in forward and reverse directions. The drive unit 10 has an ECU 20 on one side of the motor 80 in the axial direction, and is a so-called "mechatronics-integrated" type, but it may also be a mechatronics-separated type where the motor and ECU are provided separately. By making it a mechatronics-integrated type, the ECU 20 and motor 80 can be efficiently arranged in vehicles where mounting space is limited. The ECU 20 is located on the opposite side of the output shaft of the motor 80 and is arranged coaxially with respect to the axis of the shaft 870. The ECU 20 is equipped with a rotation detection device 1.

[0015] As shown in Figure 2, the rotation angle sensor 30 has detection elements 31-33 and a signal processing unit 35. The detection elements 31, 32, and 33 are provided on sensor chips 310, 320, and 330, respectively, and the signal processing unit 35 is provided on a signal processing chip 350. The sensor chips 310, 320, 330 and the signal processing chip 350 are sealed in a sealing section 38. Alternatively, for example, multiple detection elements may be provided on a single chip and separated by an insulating section.

[0016] The detection elements 31-33 are, for example, magnetoresistive elements such as AMR sensors, TMR sensors, and GMR sensors, or Hall elements, and detect the magnetic field of a sensor magnet (not shown) that rotates integrally with the shaft of the motor 80, and output a pair of analog signals, a sine signal and a cosine signal. The detection elements 31-33 may be the same, or they may have different amplitudes, etc. Also, their performance may differ, for example, detection element 31 may have higher detection accuracy than detection elements 32 and 33. If at least some of the detection elements 31-33 are of different types, the failure modes will be different, and therefore the probability of simultaneous failure can be reduced.

[0017] The signal processing unit 35 includes an AD conversion unit 351, an angle calculation unit 352, a rotation count calculation unit 353, and a communication unit 355. The AD conversion unit 351 converts the sin signal and cos signal output from the detection element 31 into digital signals.

[0018] The angle calculation unit 352 calculates the motor rotation angle θm1 using the detected value of the detection element 31, which has been digitally converted. The rotation count calculation unit 353 calculates the rotation count TC of the motor 80 using the detected value of the detection element 31, which has been digitally converted by the AD conversion unit 351. The rotation count TC can be calculated based on the count value by, for example, dividing one rotation of the motor 80 into three or more regions and counting up or down according to the direction of rotation each time the region changes.

[0019] The sealing section 38 is provided with output terminals 381 to 383 and power terminals 385 to 388. Output terminal 381 is connected to terminal 601 of the control unit 60 and is used to output a digital signal including a value calculated using the detection value of the detection element 31. Output terminal 382 is connected to terminal 602 of the control unit 60 and is used to output an analog signal corresponding to the detection value of the detection element 32. Output terminal 383 is connected to terminal 603 of the control unit 60 and is used to output an analog signal corresponding to the detection value of the detection element 33. Hereinafter, the configuration corresponding to the detection elements 31 to 33 will be referred to as a "system," the system using digital communication as a "digital system," and the system using analog communication as an "analog system."

[0020] In Figure 2, output terminals 381-383 and communication lines are provided one per system, but depending on the communication method and data method, multiple terminals may be provided in at least some systems. Amplifier circuits, filter circuits, etc. may also be provided as appropriate. Furthermore, by providing an NC (Non Connection) terminal between terminals 601-603, it is possible to prevent multiple signals from becoming abnormal due to a common cause failure such as a short circuit between adjacent terminals caused by foreign objects.

[0021] Power terminal 385 is connected to the PIG power supply 900, which is directly connected to the battery. Power terminals 386 to 388 are connected to the IG power supplies 901 to 903, which are connected to the battery via the vehicle's start switch (hereinafter referred to as "IG"). In Figure 2, the IG power supplies 901 to 903 are shown separately, but at least some of them may be common power supplies. In addition, power terminals 385 to 388 may be supplied with power that has been boosted or stepped down from each of the power supplies 900 to 903.

[0022] Power terminals 385 and 386 are connected to the sensor chip 310 and the signal processing chip 350. The detection element 31, the AD conversion unit 351, and the rotation count calculation unit 353, enclosed by the dashed line, are constantly powered via power terminal 385 even when the ignition is off. As a result, the rotation count TC calculation continues even when the ignition is off.

[0023] Furthermore, the angle calculation unit 352 and the communication unit 355 are not powered when the IG is off, and processing is stopped. Power terminal 387 is connected to the sensor chip 320, and power terminal 388 is connected to the sensor chip 330. In other words, in this embodiment, power terminals 385 to 388 are individually provided for each detection element 31 to 33, and the power supplies are configured not to interfere with each other. In addition, the detection elements 31 to 33 are configured to ensure insulation between elements.

[0024] The control unit 60 is mainly composed of a microcontroller and includes a CPU, ROM, RAM, I / O, and bus lines connecting these components (none of which are shown in the diagram). Each process in the control unit 60 may be a software process performed by executing a program pre-stored in a physical memory device such as ROM (i.e., a readable non-temporary tangible storage medium) using the CPU, or it may be a hardware process performed by a dedicated electronic circuit.

[0025] The control unit 60 includes a rotation detection unit 61 and a control calculation unit 69 as functional blocks. The rotation detection unit 61 calculates the motor rotation angle θm and absolute angle θa based on the signal from the rotation angle sensor 30 and outputs them to other calculation units such as the control calculation unit 69. The control calculation unit 69 performs various calculations related to the drive control of the motor 80. Hereinafter, the absolute angle output from the rotation detection unit 61 will be referred to as the output absolute angle θa_out.

[0026] The rotation detection unit 61 includes AD conversion units 62 and 63, an angle calculation unit 64, an absolute angle calculation unit 65, and an abnormality determination unit 68. The AD conversion unit 62 converts the analog signal output from the detection element 32 into a digital signal. The AD conversion unit 63 converts the analog signal output from the detection element 33 into a digital signal. In this embodiment, the AD conversion units 62 and 63 are provided on the control unit 60 side, and the detection signals from the detection elements 32 and 33 are not converted to digital and are output to the control unit 60 as analog signals. In other words, in the rotation angle sensor 30, the configuration related to the signal processing of the detection elements 32 and 33 is omitted, and the configuration of the rotation angle sensor 30 is simplified.

[0027] The angle calculation unit 64 calculates the motor rotation angle θm2 using the digitally converted detection value of the detection element 32, and calculates the motor rotation angle θm3 using the digitally converted detection value of the detection element 33.

[0028] The absolute angle calculation unit 65 calculates the absolute angle θa, which is the rotation angle from a reference position containing multiple rotation information, based on the motor rotation angles θm1 to θm3 and the number of rotations TC (see Figure 3). The absolute angle θa is a value that can be converted to a steering angle θs using the gear ratio, etc. Note that Figure 3 shows the case where the motor is rotated in the positive direction from the reference position.

[0029] Hereafter, the motor rotation angle θm1 based on a digital signal will be referred to as the digital rotation angle θm_d, and the motor rotation angles θm2 and θm3 based on analog signals will be referred to as the analog rotation angles θm_a. Furthermore, the absolute angle using the digital rotation angle θm_d in this calculation will be referred to as the digital absolute angle θa_d, and the absolute angle using the analog rotation angle θm_a in this calculation will be referred to as the analog absolute angle θa_a. If there is no distinction between digital and analog, the motor rotation angle will simply be referred to as θm or the absolute angle θa.

[0030] The abnormality detection unit 68 performs abnormality detection of the motor rotation angles θm1 to θm3. In this embodiment, three detection elements 31 to 33 are provided for one control unit 60. Therefore, even if an abnormality occurs in one detection element, the abnormal element can be identified, and control and abnormality monitoring can continue based on the detection values ​​of the normal elements. Hereinafter, "element abnormality" refers not only to abnormalities of the element itself, but also to signal abnormalities including abnormalities in the transmission path, etc.

[0031] Here, in calculating the absolute angle θa, information on the number of rotations TC is required at least for the initial calculation. Calculating the number of rotations TC requires a digital IC on the rotation angle sensor 30 side, and calculation delays occur due to angle calculation by the digital IC and digital communication such as SPI communication. Therefore, compared to the case where the detection signal is received as an analog signal from the rotation angle sensor 30, the calculated absolute angle also includes a delay.

[0032] Specifically, as shown in Figure 4, when the motor rotation angle θm1 and rotation count TC are calculated within the rotation angle sensor 30 using the value detected at time x0 and transmitted to the control unit 60 via digital communication, the absolute angle calculation is completed at time xd. In contrast, when angle calculations are performed within the control unit 60 using the analog rotation angle θm_a, the absolute angle calculation is completed at time xa, which is earlier than time xd. Note that in the initial calculation, the rotation count TC information is required for the absolute angle calculation, so digital communication becomes the rate-limiting step.

[0033] Therefore, in this embodiment, abnormality is determined by comparing the three motor rotation angles θm1 to θm3, and if either of the motor rotation angles θm2 or θm3 obtained via analog communication with relatively low delay is normal, absolute angle calculation is performed using the motor rotation angles θm2 and θm3.

[0034] The angle calculation process of this embodiment will be explained based on the flowchart in Figure 5. This process is performed by the control unit 60 at a predetermined interval. Hereafter, the term "step" such as step S101 will be omitted and simply referred to as the symbol "S". In this embodiment, there is one digital system and two analog systems, but the process is described as applicable even in cases with two or more digital systems, such as two digital systems and one analog system. The process in the embodiment described later is similar. Also, in the figure, the subscript (n-1) means the previous value.

[0035] In S101, the abnormality detection unit 68 performs an abnormality check on the motor rotation angles θm1 to θm3 and determines whether the normal value is 2 or greater. If it is determined that the normal value is less than 2 (S101: NO), the process proceeds to S102, where it is determined that there is an abnormality in the angle output of the motor rotation angle θm. It also notifies a higher-level ECU (not shown) of the angle output abnormality. If it is determined that the normal value is 2 or greater (S101: YES), the process proceeds to S103.

[0036] In S103, the abnormality determination unit 68 determines whether the rotation count TC is normal or not. On the rotation angle sensor 30 side, if the rotation count TC becomes abnormal due to, for example, a power failure, it transmits information indicating the TC abnormality to the control unit 60. The abnormality determination unit 68 makes an abnormality determination related to the rotation count TC based on the information from the rotation angle sensor 30. If it is determined that the rotation count TC is abnormal (S103: NO), the process proceeds to S104, where it is determined that there is an abnormality in the absolute angle calculation using the rotation count TC. It also notifies the higher-level ECU of the absolute angle calculation abnormality. If it is determined that the rotation count TC is normal (S103: YES), the process proceeds to S105. In this embodiment, since the rotation count TC is not used in the calculation of the absolute angle θa except for the first calculation, the processing in S103 and S104 can be omitted for the second and subsequent calculations.

[0037] In S105, the abnormality determination unit 68 determines whether the analog rotation angle θm_a is normal or not. In this embodiment, if at least one of the motor rotation angles θm1 and θm2 is normal, a positive determination is made. If the analog rotation angle θm_a is determined to be abnormal (S105: NO), the process proceeds to S109. If the analog rotation angle θm_a is determined to be normal (S105: YES), the process proceeds to S106.

[0038] In S106, the absolute angle calculation unit 65 determines whether it is the first calculation of the absolute angle θa. If it is determined to be the first calculation of the absolute angle θa (S106: YES), the process proceeds to S107, where the analog absolute angle θa_a is calculated using the analog rotation angle θm_a and the number of rotations TC. If it is determined not to be the first calculation of the absolute angle θa (S106: NO), the process proceeds to S108, where the analog absolute angle θa_a is calculated using the analog rotation angle θm_a and the previous value of the absolute angle θa. Specifically, the current value of the absolute angle θa is calculated by integrating the difference of the analog rotation angle θm_a. If both motor rotation angles θm2 and θm3 are normal, either value may be used, or an average value or other calculated value may be used. The same applies when there are multiple values ​​corresponding to the digital rotation angle.

[0039] If the analog rotation angle θm_a is determined to be abnormal (S105: NO), the system proceeds to S109, where, similar to S106, the absolute angle calculation unit 65 determines whether or not it is the first calculation of the absolute angle θa. If it is determined to be the first calculation (S109: YES), the system proceeds to S110, where the digital absolute angle θa_d is calculated using the digital rotation angle θm_d and the number of rotations TC. If it is determined not to be the first calculation (S109: NO), the system proceeds to S111, where the digital absolute angle θa_d is calculated using the digital rotation angle θm_d and the number of rotations TC. Specifically, the current value of the absolute angle θa is calculated by the differential integration of the digital rotation angles θm_d. The absolute angle calculation unit 65 outputs the absolute angle θa calculated in S107, S108, S110, or S111 as the output absolute angle θa_out to the control calculation unit 69.

[0040] In this embodiment, one control unit 60 is configured to acquire three sets of angle information. This makes it possible to identify normal values ​​by comparing motor rotation angles θm1, θm2, and θm3, and to perform absolute angle calculations using normal values. Furthermore, in this embodiment, if the analog rotation angle θm_a is normal, the calculation delay can be suppressed by prioritizing the use of the analog rotation angle θm_a in the absolute angle calculation.

[0041] As described above, the rotation detection device 1 comprises a rotation angle sensor 30 and a control unit 60. The rotation angle sensor 30 has at least three detection elements 31 to 33 that detect changes in physical quantities corresponding to the rotation position of the motor 80 to be detected. The rotation angle sensor 30 outputs rotation angle information related to the number of rotations TC of the motor 80 according to the detected value of at least one detection element (detection element 31 in this embodiment). The rotation angle sensor 30 also outputs rotation angle information related to the rotation angle of the motor 80 according to the detected values ​​of each of the detection elements 31 to 33 as at least one analog signal and at least one digital signal.

[0042] In this embodiment, the rotation angle sensor 30 outputs two analog signals corresponding to the detected values ​​of the detection elements 32 and 33, and one digital signal including rotation angle information and rotation count information corresponding to the detected value of the detection element 31.

[0043] The control unit 60 includes an absolute angle calculation unit 65 and an abnormality determination unit 68. The absolute angle calculation unit 65 uses rotation angle information related to the motor rotation angle θm and rotation count information related to the number of rotations TC to calculate the absolute angle θa, which is the amount of rotation from the reference position. The abnormality determination unit 68 performs abnormality determination of the rotation angle information. Specifically, the abnormality determination unit 68 performs abnormality determination by comparing the motor rotation angles θm1, θm2, and θm3.

[0044] The absolute angle calculation unit 65 outputs the absolute angle calculated using the value determined to be normal from either the analog rotation angle θm_a, which is a rotation angle based on an analog signal, or the digital rotation angle θm_d, which is a rotation angle based on a digital signal, to the control calculation unit 69. In this embodiment, the control calculation unit 69 is provided inside the control unit 60 and outputs the absolute angle θa internally, but the absolute angle θa may also be output outside the control unit 60.

[0045] This allows angle calculations to be performed with relatively little delay by outputting at least some of the detected values ​​as analog signals from the rotation angle sensor 30 to the control unit 60. Furthermore, even if there is only one control unit 60, the absolute angle θa can be calculated using values ​​identified as normal based on the detection signals of three or more detection elements 31 to 33. Moreover, if two or more detection elements are normal, the absolute angle calculation can be continued using the normal angle information.

[0046] The absolute angle calculation unit 65 calculates the analog absolute angle θa_a using the analog rotation angle θm_a and the number of rotations TC in the first calculation, provided that the analog rotation angle θm_a is normal, and calculates the analog absolute angle θa_a using the previous value and the analog rotation angle θm_a in subsequent calculations. Specifically, in subsequent calculations, the analog absolute angle θa_a is calculated by subtracting the analog rotation angle θm_a from the previous value. By prioritizing the use of the analog signal if it is normal, absolute angle calculations with low delay are possible, especially in subsequent calculations.

[0047] The absolute angle calculation unit 65 calculates the digital absolute angle θa_d using the digital rotation angle θm_d instead of the analog rotation angle θm_a if all analog rotation angles θm_a are abnormal. This allows the absolute angle calculation to continue appropriately even when the analog rotation angles θm_a are abnormal.

[0048] The rotation detection device 1 is applied to the electric power steering device 8, and the motor 80, which is the target of detection, outputs the torque required for steering. The steering angle can be calculated by converting the absolute angle θa using the gear ratio of the reduction gear 89 that transmits the drive of the motor 80 to the steering system 90. This makes it possible to omit the steering angle sensor.

[0049] (Second Embodiment) The second to fifth embodiments differ from the above embodiments in their angle calculation processing, so this point will be explained in detail. The angle calculation processing of the second embodiment will be explained based on the flowchart in Figure 6. The processing S201 to S204 in Figure 6 is the same as the processing S101 to S104 in Figure 5.

[0050] In S205, the absolute angle calculation unit 65 determines whether or not it is the first calculation of the absolute angle θa. If it is determined that it is the first calculation of the absolute angle θa (S205: YES), the process proceeds to S206. If it is determined that it is not the first calculation of the absolute angle θa (S205: NO), the process proceeds to S208.

[0051] During the initial calculation, the absolute angle calculation unit 65 calculates the analog absolute angle θa_a in S206 using the analog rotation angle θm_a and the number of rotations TC, and calculates the digital absolute angle θa_d in S207 using the digital rotation angle θm_d and the number of rotations TC.

[0052] In subsequent calculations, the absolute angle calculation unit 65 calculates the analog absolute angle θa_a in S208 using the previous values ​​of the analog rotation angle θm_a and absolute angle θa, and calculates the digital absolute angle θa_d in S209 using the previous values ​​of the digital rotation angle θm_d and absolute angle θa.

[0053] In S210, the absolute angle calculation unit 65 determines whether the analog rotation angle θm_a is normal or not. If it is determined that the analog rotation angle θm_a is normal (S210: YES), the process proceeds to S211, and the output absolute angle θa_out is set to the analog absolute angle θa_a. If it is determined that the analog rotation angle θm_a is not normal (S210: NO), the process proceeds to S212, and the output absolute angle θa_out is set to the digital absolute angle θa_d. In this embodiment, since the analog absolute angle θa_a and the digital absolute angle θa_d are calculated each time, the values ​​can be easily switched according to the abnormal situation.

[0054] In this embodiment, the absolute angle calculation unit 65 calculates, in the first calculation, an analog absolute angle θa_a calculated using the analog rotation angle θm_a as rotation angle information, and a digital absolute angle θa_d calculated using the digital rotation angle θm_d as rotation angle information. Furthermore, in the second and subsequent calculations, the absolute angle calculation unit 65 sets the value calculated by differential integration using the previous value and the analog rotation angle θm_a as the analog absolute angle θa_a, and the value calculated by differential integration using the previous value and the digital rotation angle θm_d as the digital absolute angle θa_d.

[0055] The absolute angle calculation unit 65 outputs the analog absolute angle θa_a as the output absolute angle θa_out to the control calculation unit 69 when the analog rotation angle θm_a is normal, and outputs the digital absolute angle θa_d as the output absolute angle θa_out to the control calculation unit 69 when all analog rotation angles θm_a are abnormal. This configuration also produces the same effects as the embodiment described above.

[0056] (Third embodiment) The angle calculation process of the third embodiment will be explained based on the flowchart in Figure 7. The processes in S301 to S304 are the same as the processes in S101 to S104 in Figure 5. In S305, the absolute angle calculation unit 65 calculates the analog absolute angle θa_a using the analog rotation angle θm_a and the number of rotations TC, and in S306, it calculates the digital absolute angle θa_d using the digital rotation angle θm_d and the number of rotations TC.

[0057] In S307, the absolute angle calculation unit 65 determines whether the analog rotation angle θm_a is normal or not. If it is determined that the analog rotation angle θm_a is normal (S307: YES), the process proceeds to S308, and the output absolute angle θa_out is set to the analog absolute angle θa_a. If it is determined that the analog rotation angle θm_a is not normal (S308: NO), the process proceeds to S309, and the output absolute angle θa_out is set to the digital absolute angle θa_d.

[0058] In this embodiment, the absolute angle calculation unit 65 calculates an analog absolute angle θa_a calculated using the analog rotation angle θm_a as rotation angle information, and a digital absolute angle θa_d calculated using the digital rotation angle θm_d as rotation angle information. If the analog rotation angle θm_a is normal, the absolute angle calculation unit 65 outputs the analog absolute angle θa_a as the output absolute angle θa_out to the control calculation unit 69, and if all analog rotation angles θm_a are abnormal, it outputs the digital absolute angle θa_d as the output absolute angle θa_out to the control calculation unit 69.

[0059] In other words, in this embodiment, even in the second and subsequent calculations, the absolute angle θa is calculated using the number of rotations TC each time. This configuration also produces the same effects as the embodiment described above.

[0060] (Fourth Embodiment) The angle calculation process of the fourth embodiment will be explained based on the flowchart in Figure 8. In Figure 8, steps S112 to S114 are added to the process in Figure 5. In S112, which follows S108, the control unit 60 determines whether or not it is time to perform a comparison with the calculated value using the number of rotations TC. The comparison timing can be set to any timing, such as every predetermined time or when a predetermined condition is met, such as the number of steering turns. If it is determined that it is not time to perform a comparison (S112: NO), the process from S113 onwards is skipped. If it is determined that it is time to perform a comparison (S112: YES), the process proceeds to S113. In S113, similar to S107, the absolute angle calculation unit 65 calculates the absolute angle θa using the analog rotation angle θm_a and the number of rotations TC.

[0061] The process in S114, which follows S111, is the same as the process in S112. If it is determined that it is not the time to perform a comparison (S114:NO), the processes from S115 onwards are skipped. If it is determined that it is the time to perform a comparison (S114:YES), the process proceeds to S115. In S115, similar to S110, the absolute angle calculation unit 65 calculates the absolute angle θa using the digital rotation angle θm_d and the number of rotations TC.

[0062] In S116, which follows S113 or S115, the control unit 60 compares the calculated values ​​of the absolute angle θa_e, which is calculated by integrating the difference between the previous value and the motor rotation angle θm, and the absolute angle θa_tc, which is calculated using the number of rotations TC.

[0063] In this embodiment, from the second time onward, the absolute angle θa_e is calculated by integrating the difference between the previous value and the motor rotation angle θm. However, by periodically comparing it with the absolute angle θa_tc calculated using the rotation count TC, it is possible to detect calculation errors due to soft errors, etc. Furthermore, if the difference between the absolute angle θa_e and θa_tc is greater than the judgment threshold, the absolute angle θa_tc may be set as the output absolute angle θa_out, or a correction calculation may be performed using the absolute angle θa_tc. This makes it possible to improve the calculation accuracy. In this embodiment, although the comparison of absolute angles θa_e and θa_tc was described in the angle calculation process of the first embodiment, the comparison of absolute angles θa_e and θa_tc may also be performed in the angle calculation process of the second embodiment.

[0064] In this embodiment, the absolute angle calculation unit 65 performs an absolute angle calculation using the analog rotation angle θm_a or digital rotation angle θm_d and the number of rotations TC at the comparison timing, and compares it with the absolute angle θa_e calculated using the previous value. This enables the detection of calculation errors due to soft errors, etc., and correction of calculation errors. It also provides the same effects as in the above embodiment.

[0065] (Fifth embodiment) The angle calculation process of the fifth embodiment will be explained based on the flowchart in Figure 9. The processes in S401 to S403 are the same as the processes in S101 to S103 in Figure 5. In S403, if it is determined that the rotation count TC obtained from the rotation angle sensor 30 is abnormal (S403: NO), the control unit 60 proceeds to S404, where it determines whether or not it is possible to obtain external information that can be used to calculate the rotation count TC. In this embodiment, for example, steering angle information based on the value detected by the steering sensor is used as the external information. If it is determined that external information can be obtained (S404: YES), the process proceeds to S405, where an alternative value for the rotation count TC used in the absolute angle calculation is calculated based on the external information. Alternatively, the absolute angle θa may be directly calculated from the external information and used as the initial calculation value. If it is determined that external information cannot be obtained (S404: NO), the process proceeds to S406.

[0066] The processing in S406 to S413 is the same as the processing in S104 to S111 in Figure 5. The absolute angle calculation processing from S407 onwards may be the calculation processing of the second or third embodiment.

[0067] In this embodiment, if the rotation count information obtained from the rotation angle sensor 30 is abnormal, the absolute angle calculation unit 65 calculates the absolute angle θa using external information obtained from a source other than the rotation angle sensor 30. This allows the absolute angle calculation to continue even if the rotation count information is abnormal, by substituting it with external information. This also provides the same effects as in the above embodiment.

[0068] (Other embodiments) In the above embodiment, the rotation angle sensor is provided with three detection elements and outputs one digital signal and two analog signals. In other embodiments, the number of detection elements may be four or more. Also, since there only needs to be one or more analog signals and one or more digital signals, at least one of the analog signals and digital signals will be two or more.

[0069] In the above embodiment, rotation angle information and rotation count information based on the detection value of the detection element 31 are transmitted to the control unit as a single digital signal. In other embodiments, rotation angle information and rotation count information may be transmitted separately. Furthermore, the rotation count information may use the detection value of a detection element separate from the element that detects the rotation angle information.

[0070] In the above embodiment, a power terminal is provided for each detection element. In other embodiments, multiple detection elements may share a single power terminal. Also in the above embodiment, the detection element 31, the AD conversion unit 351, and the rotation count calculation unit 353 are constantly powered. In other embodiments, it is not necessary to constantly power the detection element 31, the AD conversion unit 351, and the rotation count calculation unit 353.

[0071] In the above embodiment, the rotation angle sensor detects the rotation of the motor. In other embodiments, the rotation angle sensor may be something other than a rotation angle sensor, such as a torque sensor or a steering sensor, and the object to be detected is not limited to the motor, but may be, for example, a steering shaft.

[0072] In the above embodiment, the motor is a three-phase brushless motor. In other embodiments, the motor unit is not limited to a three-phase brushless motor, but can be any type of motor. Furthermore, the motor unit is not limited to a motor (electric motor), but can be a generator, or a so-called motor-generator that combines the functions of both an electric motor and a generator. In the above embodiment, the rotation detection device is applied to an electric power steering system. In other embodiments, the rotation detection device may be applied to a device other than an electric power steering system.

[0073] Features of the present invention may include, for example, "the rotation detection device according to any one of claims 1 to 6, wherein the absolute angle calculation unit calculates the absolute angle using external information obtained from a source other than the rotation angle sensor when the rotation count information obtained from the rotation angle sensor is abnormal," and "the rotation detection device according to any one of claims 1 to 7, which is applied to an electric power steering device (8), and the motor that is the target of detection outputs torque required for steering."

[0074] The control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor and memory programmed to perform one or more functions embodied by a computer program. Alternatively, the control unit and its method described herein may be implemented by a dedicated computer provided by configuring a processor by one or more dedicated hardware logic circuits. Alternatively, the control unit and its method described herein may be implemented by one or more dedicated computers configured by a combination of a processor and memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by the computer on a computer-readable non-transitional tangible recording medium. The present invention is not limited in any way to the embodiments described above, and can be implemented in various forms without departing from the spirit of the invention. [Explanation of Symbols]

[0075] 1. Rotation detection device 30... Rotation angle sensor 31-33...Detection element 60... Control Unit 62, 63...AD conversion section 64...Angle calculation unit 65...Absolute angle calculation unit 68...Abnormality determination section 69. Control Calculation Unit 80...Motor (Detection target)

Claims

1. A rotation angle sensor (30) having at least three detection elements (31-33) that detect changes in physical quantities corresponding to the rotational position of the object to be detected (80), A control unit (60) having an absolute angle calculation unit (65) that calculates the absolute angle, which is the amount of rotation from a reference position, using rotation angle information relating to the rotation angle of the detected target and rotation count information relating to the number of rotations of the detected target, and an abnormality determination unit (68) that determines abnormalities in the rotation angle information, Equipped with, The aforementioned rotation angle sensor is An analog signal corresponding to the detection value of at least one of the detection elements is output from the analog signal output terminals (328, 383). The system includes a signal processing unit (35) that calculates the rotation angle information and the number of rotations information using the detection value of at least one detection element different from the detection element that outputs the detection value as the analog signal, and outputs the rotation angle information and the number of rotations information as digital signals from a digital signal output terminal (381), The control unit has an angle calculation unit (64) that calculates the rotation angle information based on the analog signal, If the rotation angle information output to the control unit as a digital signal is called the digital rotation angle, and the rotation angle information calculated using the analog signal is called the analog rotation angle, The aforementioned absolute angle calculation unit, The absolute angle calculated using the value of the analog rotation angle or the digital rotation angle that is determined to be normal is output to the control calculation unit (69). A rotation detection device that, when the analog rotation angle is normal, calculates the absolute angle based on the rotation count information and the analog rotation angle included in the digital signal in at least the first calculation, and then, from the second calculation onward, preferentially outputs the absolute angle calculated using the analog rotation angle to the control calculation unit.

2. The absolute angle calculation unit, when the analog rotation angle is normal, The rotation detection device according to claim 1, wherein in the second and subsequent calculations, the absolute angle is calculated using the previous value of the absolute angle and the analog rotation angle.

3. The rotation detection device according to claim 2, wherein the absolute angle calculation unit calculates the absolute angle using the digital rotation angle instead of the analog rotation angle when all of the analog rotation angles are abnormal.

4. The aforementioned absolute angle calculation unit, In the initial calculation, the absolute angle calculated using the rotation count information and the analog rotation angle is defined as the analog absolute angle, and the absolute angle calculated using the rotation count information and the digital rotation angle is defined as the digital absolute angle. In the second and subsequent calculations, the value calculated using the previous value of the absolute angle and the analog rotation angle is defined as the analog absolute angle, and the value calculated using the previous value of the absolute angle and the digital rotation angle is defined as the digital absolute angle. The rotation detection device according to claim 1, wherein if the analog rotation angle is normal, the analog absolute angle is output to the control calculation unit, and if all of the analog rotation angles are abnormal, the digital absolute angle is output to the control calculation unit.

5. The rotation detection device according to any one of claims 2 to 4, wherein the absolute angle calculation unit performs an absolute angle calculation using the analog rotation angle or the digital rotation angle and the rotation count information at the comparison timing, and compares it with the absolute angle calculated using the previous value.

6. The absolute angle calculation unit calculates the analog absolute angle, which is the absolute angle calculated using the rotation count information and the analog rotation angle, and the digital absolute angle, which is the absolute angle calculated using the rotation count information and the digital rotation angle. The rotation detection device according to claim 1, wherein if the analog rotation angle is normal, the analog absolute angle is output to the control calculation unit, and if all of the analog rotation angles are abnormal, the digital absolute angle is output to the control calculation unit.

7. A rotation angle sensor (30) has at least three detection elements (31-33) that detect changes in physical quantities corresponding to the rotational position of the object to be detected (80), and outputs rotation count information related to the number of rotations of the object to be detected, and rotation angle information related to the rotation angle of the object to be detected, corresponding to the detection value of at least one of the detection elements. A control unit (60) having an absolute angle calculation unit (65) that calculates the absolute angle, which is the amount of rotation from a reference position, using the rotation angle information and the number of rotations information, and an abnormality determination unit (68) that determines abnormalities in the rotation angle information, Equipped with, The rotation angle sensor outputs a signal as an analog signal corresponding to the detection value of at least one of the detection elements, and outputs the rotation angle information as a digital signal corresponding to the detection value of at least one of the detection elements different from the detection element that outputs the detection value as an analog signal. The absolute angle calculation unit outputs to the control calculation unit (69) the absolute angle calculated using the value determined to be normal among the analog rotation angle, which is the rotation angle information based on the analog signal, or the digital rotation angle, which is the rotation angle information based on the digital signal. The aforementioned absolute angle calculation unit, If the aforementioned analog rotation angle is normal, In the initial calculation, the absolute angle is calculated using the rotation count information and the analog rotation angle. In the second and subsequent calculations, the absolute angle is calculated using the previous value of the absolute angle and the analog rotation angle. A rotation detection device that, at the timing of comparison, performs an absolute angle calculation using the analog rotation angle or the digital rotation angle and the rotation count information, and compares it with the absolute angle calculated using the previous value.

8. The rotation detection device according to claim 7, wherein the absolute angle calculation unit calculates the absolute angle using the digital rotation angle instead of the analog rotation angle when all of the analog rotation angles are abnormal.

9. A rotation angle sensor (30) has at least three detection elements (31-33) that detect changes in physical quantities corresponding to the rotational position of the object to be detected (80), and outputs rotation count information related to the number of rotations of the object to be detected, and rotation angle information related to the rotation angle of the object to be detected, corresponding to the detection value of at least one of the detection elements. A control unit (60) having an absolute angle calculation unit (65) that calculates the absolute angle, which is the amount of rotation from a reference position, using the rotation angle information and the number of rotations information, and an abnormality determination unit (68) that determines abnormalities in the rotation angle information, Equipped with, The rotation angle sensor outputs a signal as an analog signal corresponding to the detection value of at least one of the detection elements, and outputs the rotation angle information as a digital signal corresponding to the detection value of at least one of the detection elements different from the detection element that outputs the detection value as an analog signal. The absolute angle calculation unit outputs to the control calculation unit (69) the absolute angle calculated using the value determined to be normal among the analog rotation angle, which is the rotation angle information based on the analog signal, or the digital rotation angle, which is the rotation angle information based on the digital signal. The aforementioned absolute angle calculation unit, In the initial calculation, the absolute angle calculated using the rotation count information and the analog rotation angle is defined as the analog absolute angle, and the absolute angle calculated using the rotation count information and the digital rotation angle is defined as the digital absolute angle. In the second and subsequent calculations, the value calculated using the previous value of the absolute angle and the analog rotation angle is defined as the analog absolute angle, and the value calculated using the previous value of the absolute angle and the digital rotation angle is defined as the digital absolute angle. If the analog rotation angle is normal, the analog absolute angle is output to the control calculation unit; if all of the analog rotation angles are abnormal, the digital absolute angle is output to the control calculation unit. A rotation detection device that, at the timing of comparison, performs an absolute angle calculation using the analog rotation angle or the digital rotation angle and the rotation count information, and compares it with the absolute angle calculated using the previous value.

10. The rotation detection device according to any one of claims 1, 7, or 9, wherein the absolute angle calculation unit calculates the absolute angle using external information obtained from a source other than the rotation angle sensor when the rotation count information obtained from the rotation angle sensor is abnormal.

11. Applied to an electric power steering system (8), The motor to be detected outputs torque required for steering. This is the rotation detection device according to any one of claims 1, 7, or 9.

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