JP2013019802A - Rotation angle detection apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rotation angle detection apparatus capable of highly accurately determining whether a peak detection value to be used as an amplitude correction value is normal or not.SOLUTION: A rotation angle computing device 20 includes a function for determining peak detection values of respective detected output signals V1, V2 are normal or not before using the peak detection values as amplitude correction values. Concretely, when defining that a ratio of the peak detection value of a first output signal V1 to the peak detection value of a second output signal V2 in the same magnetic pole is set as a peak value ratio and a peak detection value to be determined as normal or not is set as a peak detection value to be determined, the rotation angle computing device 20 determines whether the peak detection value to be determined is normal or not on the basis of the peak value ratio corresponding to one magnetic pole including at least the peak detection value to be determined.

Description

  The present invention relates to a rotation angle detection device that detects a rotation angle of a rotating body such as a rotor of a brushless motor.

  In order to control a brushless motor used in an electric power steering device or the like, it is necessary to apply a current to the stator winding in accordance with the rotation angle of the rotor. Therefore, a multipolar magnet that rotates in accordance with the rotation of the rotor of the brushless motor, and a plurality of magnetic sensors that detect the magnetic flux of the multipolar magnet, and the rotation of the rotor of the brushless motor based on the output signal of each magnetic sensor. A rotation angle detection device that detects an angle is known.

However, in such a rotation angle detection device, the output characteristics of each magnetic sensor are not constant and are easily affected by the ambient temperature, so that there is an error in the rotation angle calculated based on the output signal of each magnetic sensor. Will occur.
Therefore, after detecting the peak value of the output signal of each magnetic sensor and correcting the detected peak detection value as an amplitude correction value so that the amplitude of the magnetic sensor becomes a predetermined reference value, the rotation angle of the rotor is set. A detection technique has already been developed (for example, see Patent Document 1 below).

JP 2003-83823 A JP-A-6-109750 JP 2002-345285 A

  In the conventional rotation angle detection device that corrects the amplitude of the output signal of the magnetic sensor using the peak detection value as the amplitude correction value, when a value other than the original peak value is detected as a peak value due to the influence of noise or the like. Since normal amplitude correction is not performed, an error occurs in the rotation angle calculated based on the signal after amplitude correction. Therefore, an upper limit threshold and a lower limit threshold are set for the peak detection value used as the amplitude correction value, and when the detected peak detection value exceeds the upper limit threshold or falls below the lower limit threshold, It can be considered that the peak detection value is determined to be abnormal and the peak detection value is not used as the amplitude correction value.

  However, since the magnetic flux of the multipolar magnet varies greatly depending on the ambient temperature, it is necessary to set the upper threshold value to a large value and set the lower threshold value to a small value. More specifically, since the magnetic flux of the multipolar magnet varies greatly depending on the ambient temperature, the amplitude of the output signal of the magnetic sensor decreases as the ambient temperature increases, as shown in FIG. In FIG. 8, since the magnetic flux density of the magnet, the output characteristics of the magnetic sensor, the amplifier circuit, and the like have individual variations, the value that maximizes the signal amplitude due to each variation is L1, and the minimum value is the minimum value. This is indicated by L2. For this reason, in order not to erroneously determine that the detected peak detection value is abnormal although it is normal, the upper limit threshold is set to a large value as indicated by Hth in FIG. It is necessary to set the threshold value to a small value as indicated by Lth in FIG.

Thus, if the upper limit threshold is set to a large value and the lower limit threshold is set to a small value, the interval between the upper limit threshold and the lower limit threshold becomes wider than the original amplitude of the output signal of the magnetic sensor. Therefore, it cannot be accurately determined whether or not the detected peak detection value is normal.
An object of the present invention is to provide a rotation angle detection device that can determine with high accuracy whether or not a peak detection value used as an amplitude correction value is normal.

  The invention according to claim 1 for achieving the above object is a rotation angle detecting device for detecting a rotation angle of the rotating body (1), wherein the rotating body is rotated in accordance with the rotation of the rotating body, and a plurality of magnetic poles ( M1 to M10), a plurality of magnetic sensors (21, 22) that output sine wave signals having phase differences with each other according to the rotation of the multipole magnet, Peak value detection means (20, S6) for detecting the peak value of the output signal of the magnetic sensor, and the amplitude of the output signal of each magnetic sensor is corrected using the peak detection value detected by the peak value detection means as the amplitude correction value. Amplitude correction means (20, S14) for performing rotation angle calculation means (S15) for calculating the rotation angle of the rotating body based on the output signal subjected to amplitude correction by the amplitude correction means, and the peak detection value Whether or not is normal Amplitude correction value monitoring means (20, S12) to be determined, the output signal of one of the two magnetic sensors included in the plurality of magnetic sensors as the first output signal (V1), and the other magnetic When the sensor output signal is the second output signal (V2) and the ratio of the peak detection value of the first output signal to the peak detection value of the second output signal with respect to the same magnetic pole is the peak value ratio, the amplitude The correction value monitoring unit is configured to determine whether or not the determination target peak detection value is normal based on at least a peak value ratio corresponding to one magnetic pole including the determination target peak detection value. This is a rotation angle detection device. In addition, although the alphanumeric character in parentheses represents a corresponding component in an embodiment described later, of course, the scope of the present invention is not limited to the embodiment. The same applies hereinafter.

  In the present invention, whether or not the peak detection value to be determined is normal is determined by comparing a peak value ratio corresponding to one magnetic pole including at least the peak detection value to be determined (ratio of peak detection values of output signals of two magnetic sensors). ). For this reason, the influence of the ambient temperature etc. which acts on both magnetic sensors can be offset. As a result, there are variations in the peak detection value of each output signal due to variations in the characteristics of each magnetic sensor, gaps between each magnetic sensor and the magnet, and each output signal varies depending on the ambient temperature. Even in the case of making an accurate determination, As a result, it is possible to determine with high accuracy whether or not the peak detection value to be determined is normal.

  According to a second aspect of the present invention, the peak value monitoring means corresponds to one magnetic pole including the peak detection value to be determined among the latest peak value ratios of the magnetic poles for one rotation of the rotating body. The peak value ratio is configured to determine whether or not the peak detection value to be determined is normal by comparing the peak value ratio with an average value of peak value ratios corresponding to other magnetic poles. 1. A rotation angle detection device according to 1.

  In this configuration, by comparing the peak value ratio corresponding to one magnetic pole including the peak detection value to be determined with the average value of the peak value ratios corresponding to the other magnetic poles, the peak detection value to be determined is normal. Since it is determined whether or not there is a variation, accurate determination can be made even if there is a variation in the magnetization of each magnetic pole. For this reason, it can be determined with higher accuracy whether or not the peak detection value to be determined is normal.

It is a schematic diagram which shows the structure at the time of applying the rotation angle detection apparatus which concerns on one Embodiment of this invention to the rotation angle detection apparatus for detecting the rotation angle of the rotor of a brushless motor. It is a schematic diagram which shows the structure of the rotor for a detection. It is a schematic diagram which shows the output signal waveform of the 1st and 2nd magnetic sensor, and the magnetic pole which the 1st magnetic sensor is sensing. It is a flowchart which shows the procedure of the rotation angle calculation process by a rotation angle calculating device. It is a schematic diagram which shows the 1st and 2nd peak value storage area provided in memory. It is a flowchart which shows the procedure of the setting process of the relative pole number of step S3 of FIG. It is a schematic diagram for demonstrating the setting process of a relative pole number. It is a graph which shows the change of the amplitude of the output signal of a magnetic sensor with respect to ambient temperature.

Hereinafter, an embodiment in which the present invention is applied to a rotation angle detection device for detecting the rotation angle of a rotor of a brushless motor will be described in detail with reference to the accompanying drawings.
FIG. 1 is a schematic diagram showing a configuration when a rotation angle detection device according to an embodiment of the present invention is applied to a rotation angle detection device for detecting the rotation angle of a rotor of a brushless motor.
The rotation angle detection device 100 includes a detection rotor (hereinafter simply referred to as “rotor 1”) that rotates in accordance with the rotation of the brushless motor 10. As shown in FIG. 2, the rotor 1 includes a cylindrical magnet (multipolar magnet) 2 having a plurality of magnetic pole pairs corresponding to the magnetic pole pairs provided in the rotor of the brushless motor 10.

The magnet 2 has five pairs of magnetic poles (M1, M2) (M3, M4) (M5, M6) (M7, M8) (M9, M10). That is, the magnet 2 has ten magnetic poles M1 to M10 arranged at equiangular intervals. The magnetic poles M <b> 1 to M <b> 10 are arranged at an angular interval of 36 ° (electrical angle is 180 °) around the rotation center axis of the rotor 1.
On the opposite side of the rotor 1 from the motor 10, two magnetic sensors 21 and 22 facing the annular end surface of the magnet 2 are arranged. These magnetic sensors 21 and 22 are arranged at an angle interval of a predetermined angle of 18 ° (90 ° in electrical angle) about the rotation center axis of the rotor 1. These two magnetic sensors 21 and 22 may be referred to as a first magnetic sensor 21 and a second magnetic sensor 22, respectively. As the magnetic sensor, for example, a sensor provided with an element having a characteristic in which an electrical characteristic is changed by the action of a magnetic field, such as a Hall element or a magnetoresistive element (MR element) can be used.

  A direction indicated by an arrow in FIG. 2 is a positive rotation direction of the rotor 1. When the rotor 1 is rotated in the forward direction, the rotation angle of the rotor 1 is increased. When the rotor 1 is rotated in the reverse direction, the rotation angle of the rotor 1 is decreased. As shown in FIG. 3, each magnetic sensor 21, 22 is a sine wave signal having a period during which the rotor 1 rotates at an angle corresponding to one magnetic pole pair (72 ° (360 ° in electrical angle)). V1 and V2 are output.

  FIG. 3 shows the rotor angle (mechanical angle) when the rotation angle of the rotor 1 is 0 ° when the boundary between the magnetic pole M10 and the magnetic pole M1 of the rotor 1 faces the first magnetic sensor 21. Output signals V1 and V2 of the magnetic sensors 21 and 22 are shown. The output signals V1 and V2 of the magnetic sensors 21 and 22 are actually signals obtained by amplifying the output of the sensor element by an amplifier circuit. FIG. 3 shows magnetic poles M1 to M10 sensed by the first magnetic sensor 21 corresponding to the rotor angle.

The angle range for one rotation of the rotor 1 is divided into five sections corresponding to the five magnetic pole pairs, and the rotation angle of the rotor 1 expressed as the start position of each section is 0 ° and the end position is 360 ° An electrical angle θe of 1 is assumed.
Here, it is assumed that the first magnetic sensor 21 outputs an output signal of V1 = A1 · sin θe for each section corresponding to five magnetic pole pairs. In this case, the second magnetic sensor 22 outputs an output signal of V2 = A2 · sin (θe + 90 °) = A2 · cos θe for each section corresponding to the five magnetic pole pairs. A1 and A2 each represent an amplitude. Therefore, the magnetic sensors 21 and 22 output sine wave signals having a predetermined phase difference of 90 ° (electrical angle). The output signals V1 and V2 of the magnetic sensors 21 and 22 may be referred to as a first output signal V1 and a second output signal V2, respectively.

The amplitudes A1 and A2 of V1 and V2 of each output signal vary depending on the following factors.
-Magnetization variation and temperature characteristic of each magnetic pole M1-M8-Characteristic variation and temperature characteristic of each magnetic sensor 21, 22-Gain variation and temperature characteristic of amplification circuit corresponding to each magnetic sensor 21, 22- Axial spacing (gap) between the magnetic sensors 21 and 22 and the magnet 2
Distance between the rotation center axis of the rotor 1 and the magnetic sensors 21 and 22 Returning to FIG. 1, the output signals V1 and V2 of the magnetic sensors 21 and 22 are input to the rotation angle calculation device 20. The rotation angle calculation device 20 is composed of, for example, a microcomputer, and includes a CPU (Central Processing Unit) and a memory (ROM, RAM, rewritable nonvolatile memory, etc.).

  The rotation angle calculation device 20 detects the peak values of the output signals V1, V2 of the magnetic sensors 21, 22. Further, the rotation angle calculation device 20 corrects the amplitude of the corresponding output signal using the detected peak detection values of the output signals V1 and V2 as amplitude correction values. Then, the rotation angle calculation device 20 calculates the rotation angle (electrical angle θe) of the rotor 1 based on the output signals V1 ′ and V2 ′ after amplitude correction.

The electrical angle θe calculated by the rotation angle calculation device 20 is given to the motor controller 30. The motor controller 30 controls the brushless motor 10 using the electrical angle θe given from the rotation angle calculation device 20.
In this embodiment, the rotation angle calculation device 20 determines whether or not the peak detection value is normal before the detected peak detection values of the output signals V1 and V2 are used as amplitude correction values. It has a function. Specifically, the peak detection value that should be determined whether or not the peak value ratio is the ratio of the peak detection value of the first output signal V1 to the peak detection value of the second output signal V2 for the same magnetic pole. Is the determination target peak detection value, the rotation angle calculation device 20 determines whether or not the determination target peak detection value is normal based on the peak value ratio corresponding to each magnetic pole in the latest one round of the rotor 1. Determine whether. When it is determined that the peak detection value is not normal, the rotation angle calculation process is stopped and the rotation of the motor 1 is stopped.

FIG. 4 is a flowchart showing a procedure of rotation angle calculation processing by the rotation angle calculation device 20.
The rotation angle calculation process shown in FIG. 4 is repeatedly performed every predetermined calculation cycle.
Using the magnetic pole sensed by the first magnetic sensor 21 at the start of the rotation angle calculation process as a reference magnetic pole, the number of each magnetic pole when a relative number is assigned to each magnetic pole is defined as a relative pole number. The relative pole number of the magnetic pole sensed by the first magnetic sensor 21 (hereinafter referred to as “first relative pole number”) is represented by a variable r1, and the magnetic pole sensed by the second magnetic sensor 22 is represented by the variable r1. The relative pole number (hereinafter referred to as “second relative pole number”) is represented by a variable r2. Each of the relative pole numbers r1 and r2 takes an integer of 1 to 10, and the relative pole number 1 less than 1 is 10, and the relative pole number 1 larger than 10 is 1.

  In this embodiment, when the magnetic pole (reference magnetic pole) sensed by the first magnetic sensor 21 at the start of the rotation angle calculation process is an N-pole, the relative pole number “1” is assigned to the magnetic pole. Is assigned. On the other hand, when the magnetic pole (reference magnetic pole) sensed by the first magnetic sensor 21 at the start of the rotation angle calculation process is an S pole, a relative pole number of “2” is assigned to the magnetic pole. It is done.

As shown in FIG. 5, the memory (for example, RAM) of the rotation angle calculation device 20 is provided with first and second peak value storage areas R1, R2. In the first peak value storage area R1, the first output signal V1 detected most recently with respect to the magnetic pole corresponding to the relative pole number for every 1 to 10 of the first relative pole number r1. The peak detection values a _{1 to} a ₁₀ are stored. In the second peak value storage area R2, the second output signal V2 detected most recently with respect to the magnetic pole corresponding to the relative pole number for each of the second relative pole numbers r2 1-10. The peak detection values b _{1 to} b ₁₀ are stored.

  When the rotation angle calculation process is started, the rotation angle calculation device 20 reads the output signals (sensor values) V1 and V2 of the magnetic sensors 21 and 22 (step S1). In the memory (for example, RAM) of the rotation angle calculation device 20, a plurality of times of sensors from the sensor value read a predetermined number of times to the latest read sensor value are output for each of the output signals V1 and V2. The value is stored.

  In this embodiment, in order to detect the peak value (maximum value and minimum value) of the sensor value V1, a sensor value having a larger absolute value among the read sensor values V1 is a peak value candidate of the sensor value V1. Is stored in memory. Similarly, in order to detect the peak value (maximum value and minimum value) of the sensor value V2, a sensor value having a larger absolute value among the read sensor values V2 is stored in the memory as a peak value candidate of the sensor value V2. Is done. However, these peak value candidates are reset to zero at a predetermined timing, which will be described later, when a zero cross of the corresponding output signal is detected.

When the sensor values V1 and V2 are read in step S1, the rotation angle calculation device 20 determines whether or not the current process is the first process after the start of the rotation angle calculation process (step S2). If the current process is the first process after the start of the rotation angle calculation process (step S2: YES), the rotation angle calculation device 20 performs a relative pole number setting process (step S3).
FIG. 6 shows the detailed procedure of the relative pole number setting process.

  First, the rotation angle calculation device 20 determines whether or not the first output signal V1 is greater than 0 (step S21). When the first output signal V1 is greater than 0 (step S21: YES), the rotation angle calculation device 20 has an N-pole magnetic pole (reference magnetic pole) sensed by the first magnetic sensor 21. And the first relative pole number r1 is set to 1 (step S24). Then, the process proceeds to step S26.

  On the other hand, when the first output signal V1 is 0 or less (step S21: NO), the rotation angle calculation device 20 determines whether or not the first output signal V1 is smaller than 0 (step S22). . If the first output signal V1 is smaller than 0 (step S22: YES), it is determined that the magnetic pole (reference magnetic pole) sensed by the first magnetic sensor 21 is the S magnetic pole, and the first The relative pole number r1 is set to 2 (step S25). Then, the process proceeds to step S26.

  If it is determined in step S22 that the first output signal V1 is equal to or greater than 0 (step S22: NO), that is, if the first output signal V1 is 0, the rotation angle calculation device. 20 determines whether the second output signal V2 is greater than 0 in order to determine whether the rotor rotation angle (electrical angle) is 0 ° or 180 ° (step S23). When the second output signal V2 is greater than 0 (step S23: YES), the rotation angle calculation device 20 determines that the rotor rotation angle (electrical angle) is 0 °, and the first relative pole number is determined. r1 is set to 1 (step S24). Then, the process proceeds to step S26.

On the other hand, when the second output signal V2 is 0 or less (step S23: NO), the rotation angle calculation device 20 determines that the rotor rotation angle (electrical angle) is 180 °, and the first relative The target pole number r1 is set to 2 (step S25). Then, the process proceeds to step S26.
In step S26, the rotation angle calculation device 20 determines whether or not the condition of “V1> 0 and V2 ≦ 0” or “V1 <0 and V2 ≧ 0” is satisfied. When this condition is satisfied (step S26: YES), the rotation angle calculation device 20 detects the pole number of the magnetic pole sensed by the second magnetic sensor 22 by the first magnetic sensor 21. It is determined that the number is 1 larger than the pole number of the existing magnetic pole, and a number (r2 = r1 + 1) larger by 1 than the first relative pole number r1 is set as the second relative pole number r2 (step S27). ). And it transfers to step S16 of FIG.

  On the other hand, when the condition of step S26 is not satisfied (step S26: NO), the rotation angle calculation device 20 indicates that the pole number of the magnetic pole sensed by the second magnetic sensor 22 is the first magnetic sensor. 21 is determined to be the same as the pole number of the magnetic pole sensed, and the same number (r2 = r1) as the first relative pole number r1 is set as the second relative pole number r2 (step S28). . And it transfers to step S16 of FIG.

When the condition of step S26 is satisfied, a number (r2 = r1 + 1) larger than the first relative pole number r1 by 1 is set for the second relative pole number r2, and the condition of step S26 is satisfied. The reason why the same number (r2 = r1) as the first relative pole number r1 is set in the second relative pole number r2 in the case where the second relative pole number r2 is not set will be described.
For example, the signal waveforms of the output signals V1, V2 of the first and second magnetic sensors 21, 22 when the magnetic pole pair composed of the magnetic pole M1 and the magnetic pole M2 in the rotor 1 passes through the first magnetic sensor 21 are schematically shown. If it represents, it will come to show to Fig.7 (a) (b).

  7A and 7B, a region indicated by S1 is a region where the first magnetic sensor 21 senses the magnetic pole M1 and the second magnetic sensor 22 senses the magnetic pole M1. The region indicated by S2 is a region where the first magnetic sensor 21 senses the magnetic pole M1 and the second magnetic sensor 22 senses the magnetic pole M2. The region indicated by S3 is a region where the first magnetic sensor 21 senses the magnetic pole M2 and the second magnetic sensor 22 senses the magnetic pole M2. The region indicated by S4 is a region where the first magnetic sensor 21 senses the magnetic pole M2 and the second magnetic sensor 22 senses the magnetic pole M3.

That is, in the areas S1 and S3, the pole number of the magnetic pole sensed by the second magnetic sensor 22 is the same as the pole number of the magnetic pole sensed by the first magnetic sensor 21. On the other hand, in the regions S2 and S4, the pole number of the magnetic pole sensed by the second magnetic sensor 22 is larger by 1 than the pole number of the magnetic pole sensed by the first magnetic sensor 21.
In the region S1, the sensor values V1 and V2 satisfy the first condition of V1 ≧ 0 and V2> 0. In the region S2, both sensor values V1 and V2 satisfy the second condition of V1> 0 and V2 ≦ 0. In the region S3, the sensor values V1 and V2 satisfy the third condition of V1 ≦ 0 and V2 <0. In the region S4, both sensor values V1 and V2 satisfy the fourth condition of V1 <0 and V2 ≧ 0.

  Therefore, when the rotation angle calculation device 20 satisfies the second condition (V1> 0 and V2 ≦ 0) or the fourth condition (V1 <0 and V2 ≧ 0), the second magnetic sensor 22 is provided. The pole number of the magnetic pole sensed by is determined to be 1 larger than the pole number of the magnetic pole sensed by the first magnetic sensor 21, and if the second condition or the fourth condition is not satisfied, The pole number of the magnetic pole sensed by the second magnetic sensor 22 is determined to be the same as the pole number of the magnetic pole sensed by the first magnetic sensor 21.

Returning to FIG. 4, if it is determined in step S2 that the current process is not the first process after the start of the rotation angle calculation process (step S2: NO), the process proceeds to step S4.
In step S4, the rotation angle calculation device 20 determines, based on the sensor values V1 and V2 stored in the memory, whether or not a zero cross where the sign of the sensor value is inverted is detected for each of the sensor values V1 and V2. To do. When the zero cross is not detected (step S4: NO), the rotation angle calculation device 20 proceeds to step S5.

If a zero cross is detected for one of the sensor values V1 and V2 in step S4 (step S4: YES), the rotation angle calculation device 20 causes the peak value (maximum) of the output signal from which the zero cross is detected. (Peak value or local minimum value) is detected (step S6).
The peak value detection process will be specifically described. The magnetic sensor corresponding to the output signal in which the zero cross is detected in step S4 will be referred to as a peak value detection target magnetic sensor. First, the rotation angle calculation device 20 determines whether or not the magnetic pole sensed by the magnetic sensor that is the peak value detection target has changed. In other words, the rotation angle calculation device 20 differs in the magnetic pole position sensed by the peak value detection target magnetic sensor between the time when the zero cross of the output signal of the magnetic sensor was detected last time and the time when it was detected this time. Or whether they are the same. When the rotation direction of the rotor 1 is reversed, the magnetic pole positions at both time points may be the same.

  This determination can be made based on, for example, whether or not the rotation direction of the rotor 1 when the zero crossing of the output signal of the magnetic sensor was previously detected and the current rotation direction of the rotor 1 are the same direction. . That is, if the rotation direction of the rotor 1 is the same direction, the rotation angle calculation device 20 determines that the magnetic pole sensed by the peak value detection target magnetic sensor has changed. On the other hand, if the rotation direction of the rotor 1 is different, the rotation angle calculation device 20 determines that the magnetic pole sensed by the magnetic sensor that is the peak value detection target has not changed.

  When it is determined that the magnetic pole sensed by the magnetic sensor targeted for peak value detection has changed, the rotation angle calculation device 20 determines that the peak value has been detected, and the peak value candidate corresponding to the magnetic sensor. Is identified as the peak detection value. On the other hand, when it is determined that the magnetic pole sensed by the magnetic sensor has not changed, the rotation angle calculation device 20 determines that the peak value has not been detected.

  Note that the rotation direction of the rotor 1 can be determined based on the previous value and the current value of the output signal in which the zero cross is detected and the current value of the other one output signal. Specifically, when the output signal in which the zero cross is detected is the first output signal V1, “the previous value of the first output signal V1 is greater than 0 and its current value is less than or equal to 0, The condition that the output signal V2 of 2 is smaller than 0, or that the previous value of the first output signal V1 is less than 0 and its current value is 0 or more, and the second output signal V2 is greater than 0. If the condition is satisfied, the rotation direction is determined to be the positive direction (the direction indicated by the arrow in FIG. 2).

On the other hand, the condition that “the previous value of the first output signal V1 is greater than or equal to 0 and the current value is less than 0 and the second output signal V2 is greater than 0” or “the previous time of the first output signal V1. When the condition that the value is 0 or less and the current value is greater than 0 and the second output signal V2 is less than 0 is satisfied, the rotation direction is determined to be the reverse direction.
When the output signal in which the zero cross is detected is the second output signal V2, “the previous value of the second output signal V2 is greater than 0 and the current value is less than or equal to 0, and the first output signal V1 Or the condition that the previous value of the second output signal V2 is less than 0 and the current value is 0 or more and the first output signal V1 is less than 0 is satisfied. In this case, the rotation direction is determined to be the positive direction (the direction indicated by the arrow in FIG. 2). On the other hand, the condition that “the previous value of the second output signal V2 is 0 or more and the current value is less than 0 and the first output signal V1 is less than 0” or “the previous time of the second output signal V2” When the condition that the value is 0 or less and the current value is greater than 0 and the first output signal V1 is greater than 0 is satisfied, the rotation direction is determined to be the reverse direction.

When the peak value is detected in step S6 (step S7: YES), the rotation angle calculation device 20 resets the peak value candidate corresponding to the output signal in which the zero cross is detected in step S4 to zero, Peak value update processing is performed (step S8).
In the peak value update process, the rotation angle calculation device 20 applies to the magnetic sensor in which the peak value is detected in step S6 among the peak detection values in the peak value storage areas R1, R2 in the memory (see FIG. 5). The peak detection value corresponding to the currently set relative pole number r1 or r2 is updated to the peak detection value detected in step S6. When the peak value update process ends, the rotation angle calculation device 20 proceeds to step S9.

If the peak value is not detected in step S6 (step S7: NO), the rotation angle calculation device 20 resets the peak value candidate corresponding to the output signal in which the zero cross is detected in step S4 to zero. Thereafter, the process proceeds to step S9 without performing the peak value update process.
In step S9, the rotation angle calculation device 20 performs a relative pole number update process. Specifically, the relative pole number r1 or r2 currently set for the magnetic sensor in which the zero cross is detected in step S4 is increased by 1 or decreased by 1 depending on the rotation direction of the rotor 1. Change to a number.

  When the rotation direction of the rotor 1 is the positive direction (the direction indicated by the arrow in FIG. 2), the rotation angle calculation device 20 is set to the current set relative to the magnetic sensor in which the zero cross is detected in step S4. The target pole number r1 or r2 is updated to a number larger by one. On the other hand, when the rotation direction of the rotor 1 is the reverse direction, the rotation angle calculation device 20 decreases the relative pole number r1 or r2 currently set for the magnetic sensor in which the zero cross is detected by one. Update to a number. However, as described above, the relative pole number that is smaller by 1 than the relative pole number of “1” is “10”. Further, the relative pole number that is larger by 1 than the relative pole number of “10” is “1”.

  When the relative pole number update process in step S9 is completed, the rotation angle calculation device 20 starts the rotation angle calculation process, and then the peak values of the first and second output signals V1 and V2 for all the magnetic poles M1 to M10. Is detected (step S10). That is, after the rotation angle calculation process is started, the rotation angle calculation device 20 and the peak value of the first output signal V1 corresponding to 1 to 10 of the first relative pole number r1 and the second relative pole number, respectively. It is determined whether or not the peak values of the second output signal V2 corresponding to 1 to 10 of r2 are detected.

  When the peak values of the first and second output signals V1 and V2 for all the magnetic poles M1 to M10 are not detected (step S10: NO), the rotation angle calculation device 20 proceeds to step S16. On the other hand, when the peak values of the first and second output signals V1, V2 for all the magnetic poles M1 to M10 are detected (step S10: YES), the rotation angle calculation device 20 sets the flag F ( After F = 1) (step S11), the process proceeds to step S12. The flag F is reset (F = 0) at the start of the rotation angle calculation process.

  In step S12, the rotation angle calculation device 20 performs an amplitude correction value monitoring process. The amplitude correction value monitoring process will be described. In the amplitude correction process in step S14 described later, the amplitude of the first output signal V1 is determined using the peak detection value of the first output signal V1 corresponding to the magnetic pole currently sensed by the first magnetic sensor 21 as an amplitude correction value. Is corrected, and the amplitude of the second output signal V2 is corrected using the peak detection value of the second output signal V2 corresponding to the magnetic pole currently sensed by the second magnetic sensor 22 as an amplitude correction value. .

  Therefore, in the amplitude correction value monitoring process, the rotation angle computing device 20 detects the peak detection value (hereinafter referred to as “first output signal V1”) of the first output signal V1 corresponding to the magnetic pole currently sensed by the first magnetic sensor 21. The peak detection value of the determination target) and the peak detection value of the second output signal V2 corresponding to the magnetic pole currently sensed by the second magnetic sensor 22 (hereinafter referred to as the “peak detection value of the second determination target”). ) Is normal or abnormal. Note that the peak detection value of the first determination target and the peak detection value of the second determination target may be collectively referred to as “determination target peak detection value”.

First, a method for determining whether or not the peak detection value of the first determination target is normal will be described.
In the first peak value storage area R1 of FIG. 5, the peak detection value of the first output signal V1 being stored for 1 to 10 of the first relative pole number _r1, in a 1 _{~a 10} I will represent it. In the second peak value storage area R2, the peak detection value of the second output signal V2 being stored for 1 to 10 second relative pole number _r2, represented by b 1 _{~b 10} I will decide.

The peak detection values a _{1 to} a ₁₀ of the first output signal V1 are represented by a _k (k = 1, 2,..., 10) using the variable k representing the value of the first relative pole number r1. There is a case. Similarly, the peak detection values b _{1 to} b ₁₀ of the second output signal V2 are converted into b _k (k = 1, 2,..., 10 using the variable k representing the value of the second relative pole number r2. ). Between the peak values a _k and b _k of the output signals V1 and V2, the peak detection values of the output signals V1 and V2 having the same relative number value k indicate the peak values for the same magnetic pole. In addition, the ratio (a _k / b _k ) between the peak detection values a _k and b _k of the two output signals V1 and V1 for the same magnetic pole may be referred to as a peak value ratio.

The peak detection value of the first determination target is the relative magnetic pole number currently detected by the first magnetic sensor 21 (the currently set first relative magnetic pole number r1) is n (n is 1). When the take one of the values 10), represented by a _n. Also, the peak detection value of the second output signal V2 corresponding to the magnetic poles is represented by b _n.
In this case, the rotation angle calculation device 20 determines whether or not both the first condition represented by the following expression (1a) and the second condition represented by the following expression (1b) are satisfied. When both the first condition and the second condition are satisfied, the rotation angle calculation device 20 determines that the peak detection value of the first determination target is normal. On the other hand, when at least one of the first condition and the second condition is not satisfied, the rotation angle calculation device 20 determines that the peak detection value of the first determination target is abnormal.

(A _n / b _n ) on the left side of the formula (1a) and the formula (1b) represents the peak value ratio corresponding to the magnetic pole that the first magnetic sensor 21 is currently sensing.
In addition, [{(Σ (a _k / b _k )) − a _n / b _n } / 9] on the right side of the formula (1a) and the formula (1b) _represents all the magnetic poles M 1 provided in the magnet 2. The average value of the peak value ratios corresponding to magnetic poles other than the magnetic pole currently sensed by the first magnetic sensor 21 among .about.M10. Further, “0.04” on the right side of the equations (1a) and (1b) represents a margin. The margin may be a value other than 0.04.

Therefore, the first condition is that “the peak value ratio (a _n / b _n ) corresponding to the magnetic pole currently sensed by the first magnetic sensor 21 is other than the magnetic pole currently sensed by the first magnetic sensor 21. The average value of the peak value ratios corresponding to the magnetic poles is equal to or greater than a value obtained by multiplying 0.96 ”.
The second condition is that “the peak value ratio (a _n / b _n ) corresponding to the magnetic pole currently sensed by the first magnetic sensor 21 is other than the magnetic pole currently sensed by the first magnetic sensor 21. The average value of the peak value ratios corresponding to the magnetic poles of the magnetic poles is equal to or less than a value obtained by multiplying 1.04 ”.

That is, the rotation angle calculation device 20 has a peak value ratio (a) corresponding to one magnetic pole including the peak detection value of the first determination target among the peak value ratios of the respective magnetic poles in the latest one round of the rotor 1. _n / b _n ) is compared with the average value [{(Σ (ak / bk)) − a _n / b _n } / 9] of the peak value ratios corresponding to the other magnetic poles to determine the first determination target It is determined whether or not the detected peak value is normal.

When determining whether or not the peak detection value of the second determination target is normal, the second magnetic sensor 22 currently senses n in the above formula (1a) and the above formula (1b). It may be replaced with the relative pole number of the magnetic pole (the currently set second relative pole number r2).
In this way, whether or not the peak detection value to be determined is normal is determined based on the ratio of the peak values of the two output signals V1 and V2. Therefore, variations in the characteristics of the magnetic sensors 21 and 22, Variations in characteristics of amplifier circuits corresponding to the sensors 21 and 22, variation in gaps between the magnetic sensors 21 and 22 and the magnet 2, variation in distance between the rotation center axis of the rotor 1 and the magnetic sensors 21 and 22, etc. Even when there are variations between the peak detection values of the output signals V1 and V2 due to the above, or when the output signals V1 and V2 fluctuate due to the ambient temperature, an accurate determination can be made.

  Moreover, the peak detection value to be determined is normal by comparing the peak value ratio corresponding to the magnetic pole currently sensed by each magnetic sensor with the average value of the peak value ratios corresponding to the magnetic poles other than the magnetic pole. Therefore, even if there is a variation in the magnetization of each magnetic pole, accurate determination can be made. For this reason, it can be determined with high accuracy whether or not the peak detection value to be determined is normal.

  In the amplitude correction value monitoring process, when it is determined that both the peak detection value of the first determination target and the peak detection value of the second determination target are normal (step S13: YES), the rotation angle calculation device 20 performs an amplitude correction process (step S14). That is, the rotation angle calculation device 20 includes the peak detection value (the peak detection value of the first determination target) of the first output signal V1 corresponding to the magnetic pole sensed by the first magnetic sensor 21, and the second Each output is based on the peak detection value (second detection target peak detection value) of the second output signal V2 corresponding to the magnetic pole sensed by the magnetic sensor 22 and the preset reference amplitude A. The amplitudes of the signals V1 and V2 are corrected.

Specifically, the peak detection value of the first determination target is a _r1 , the peak detection value of the second determination target is b _r2, and the signals after amplitude correction of the first and second output signals V1 and V2 Are V1 ′ and V2 ′, respectively, the corrected first and second output signals V1 ′ and V2 ′ are calculated based on the following equations (2) and (3), respectively.
V1 ′ = (V1 / _ar1 ) × A (2)
V2 ′ = (V2 / b _r2 ) × A (3)
When the amplitude correction process ends, the rotation angle calculation device 20 proceeds to step S15. In step S15, the rotation angle calculation device 20 calculates the rotation angle (electrical angle θe) of the rotor 1 based on the output signals V1 ′ and V2 ′ after amplitude correction. Specifically, the electrical angle θe of the rotor 1 is calculated based on the following equation (4).

θe = tan ⁻¹ (V1 ′ / V2 ′) (4)
When the electrical angle θe is calculated in step S15, the rotation angle calculation device 20 gives the electrical angle θe to the motor controller 30. Then, the processing in the current calculation cycle is finished.
In step S5, the rotation angle calculation device 20 determines whether or not the flag F is set. When the flag F is not set (step S5: NO), the rotation angle calculation device 20 proceeds to step S16. On the other hand, when the flag F is set (step S5: YES), the peak detection values (peak detection values to be determined) corresponding to the magnetic poles currently sensed by the magnetic sensors 21 and 22 are already normal. Since it is determined that there is, the rotation angle calculation device 20 proceeds to step S14.

In step S16, the rotation angle calculation device 20 calculates the electrical angle θe based on the sensor values V1 and V2 read in step S1. Specifically, the electrical angle θe of the rotor 1 is calculated based on the following equation (5).
θe = tan ⁻¹ (V1 / V2) (5)
When the electrical angle θe is calculated in step S16, the rotation angle calculation device 20 gives the electrical angle θe to the motor controller 30. Then, the processing in the current calculation cycle is finished.

  In the amplitude correction value monitoring process of step S12, when it is determined that at least one of the peak detection value of the first determination target and the peak detection value of the second determination target is abnormal (step S13: NO) The rotation angle calculation device 20 performs an abnormality process (step S17). Specifically, the rotation angle calculation device 20 stops the rotation angle calculation process and outputs a motor stop command to the motor controller 30. Thereby, the motor 10 is stopped.

According to the embodiment, the rotation angle calculation device 20 uses the peak detection value detected by the rotation angle calculation device 20 after each rotation of the rotor 1 after the rotation angle calculation processing, and outputs each output signal V1. , V2 can be corrected. Thereby, the rotation angle (electrical angle) θe of the rotor 1 can be calculated with high accuracy.
Further, whether or not a peak detection value that may be used for amplitude correction is normal is determined based on variations in the characteristics of the magnetic sensors 21 and 22, variations in the characteristics of the amplifier circuit, and the magnetic sensors 21 and 22 and the magnet 2. Can be accurately determined irrespective of variations in the gap between the rotation center axis of the rotor 1 and variations in the distance between the magnetic sensors 21 and 22, variations in magnetization of the magnetic poles, changes in the ambient temperature, and the like. As a result, the reliability of the output signal after amplitude correction is improved.

  As mentioned above, although embodiment of this invention was described, this invention can also be implemented with another form. For example, in the above-described embodiment, sine wave signals having a phase difference of 90 ° are output from the two magnetic sensors 21 and 22, but the phase difference is an angle other than 90 ° (for example, 120 °). As shown, two magnetic sensors may be arranged. Three or more magnetic sensors may be provided.

  Further, in the embodiment, the rotation angle calculation device 20 has a peak value ratio corresponding to one magnetic pole including the peak detection value to be determined among the peak value ratios of the respective magnetic poles in the latest one round of the rotor 1. Is compared with the average value of the peak value ratios corresponding to the other magnetic poles to determine whether or not the peak detection value to be determined is normal. The target to be compared with the peak value ratio corresponding to the magnetic pole may not be the average value of the peak value ratios corresponding to the other magnetic poles. The target to be compared with the peak value ratio corresponding to one magnetic pole including the peak detection value to be determined may be a preset set value, for example.

Further, when there are two or more peak value ratios that are extremely different from each other in the peak value ratios corresponding to the magnetic poles, it is determined that the peak detection value to be determined is abnormal. Also good. Such a situation occurs, for example, when one of the magnetic sensors fails.
If it is determined that there is an abnormality, the sensor signal that is abnormal may be specified, the rotation angle may be calculated (estimated) based on the normal sensor signal, and the motor drive may be continued.

  In the embodiment, the flag F is set when it is determined in step S10 in FIG. 2 that the peak values for all the magnetic poles have been detected. Instead, the amplitude correction value monitoring in step S12 is performed. In the process, when it is determined that both the peak detection value of the first determination target and the peak detection value of the second determination target are normal (step S13: YES), the flag F is set. Also good.

The present invention can also be applied when detecting the rotation angle of a rotating body other than the rotor of a brushless motor.
In addition, various design changes can be made within the scope of matters described in the claims.

  DESCRIPTION OF SYMBOLS 1 ... Detection rotor, 2 ... Magnet, 21, 22 ... Magnetic sensor, 10 ... Brushless motor, 20 ... Rotation angle arithmetic unit, M1-M10 ... Magnetic pole

Claims (2)

A rotation angle detection device for detecting a rotation angle of a rotating body,
A multipolar magnet that rotates according to the rotation of the rotating body and includes a plurality of magnetic poles;
A plurality of magnetic sensors that output sinusoidal signals having a phase difference with each other in accordance with the rotation of the multipole magnet;
A peak value detecting means for detecting a peak value of an output signal of each magnetic sensor;
Amplitude correction means for correcting the amplitude of the output signal of each magnetic sensor using the peak detection value detected by the peak value detection means as an amplitude correction value;
A rotation angle calculation means for calculating a rotation angle of the rotating body based on an output signal subjected to amplitude correction by the amplitude correction means;
Amplitude correction value monitoring means for determining whether or not the peak detection value is normal,
The output signal of one of the two magnetic sensors included in the plurality of magnetic sensors is set as a first output signal, the output signal of the other magnetic sensor is set as a second output signal, and the first output for the same magnetic pole is set. When the ratio of the peak detection value of the output signal and the peak detection value of the second output signal is a peak value ratio, the amplitude correction value monitoring means corresponds to a peak corresponding to one magnetic pole including at least the peak detection value to be determined. A rotation angle detection device configured to determine whether or not the peak detection value to be determined is normal based on a value ratio.   The peak value monitoring means calculates a peak value ratio corresponding to one magnetic pole including the peak detection value to be determined, among the latest peak value ratios of the magnetic poles for one rotation of the rotating body, as another magnetic pole. The rotation angle detection device according to claim 1, wherein the rotation angle detection device is configured to determine whether or not the peak detection value as the determination target is normal by comparing with an average value of peak value ratios corresponding to. .

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