WO2022208913A1

WO2022208913A1 - Position detection device and position detection method

Info

Publication number: WO2022208913A1
Application number: PCT/JP2021/022352
Authority: WO
Inventors: 淳藤田
Original assignee: 日本電産株式会社
Priority date: 2021-03-30
Filing date: 2021-06-11
Publication date: 2022-10-06
Also published as: JP7452757B2; CN117121363A; JPWO2022208913A1

Abstract

One embodiment of a position detection device according to this invention comprises three magnetic sensors and a signal processing unit for processing a three-phase signal output from the three magnetic sensors. The signal processing unit executes: acquisition processing for acquiring the instantaneous value Hu' of a U-phase signal, the instantaneous value Hv' of a V-phase signal, and the instantaneous value Hw' of a W-phase signal; abnormality discernment processing for specifying an abnormal sensor that is a magnetic sensor from among the three magnetic sensors that is abnormal by determining whether the instantaneous value Hu' of the U-phase signal, the instantaneous value Hv' of the V-phase signal, and the instantaneous value Hw' of the W-phase signal satisfy formula (1) in all of a first case, second case, and third case; signal generation processing for using the two-phase signal output from the two magnetic sensors other than the abnormal sensor to generate the remaining single-phase signal; and position estimation processing for estimating the rotation position of a motor on the basis of the two-phase signal output from the two magnetic sensors other than the abnormal sensor and the generated remaining single-phase signal.

Description

Position detection device and position detection method

The present invention relates to a position detection device and a position detection method.

The following Patent Document 1 discloses a rotation detection device that is capable of continuously detecting rotation even if an abnormality occurs in a part of the circuit by providing two circuits necessary for detecting the rotation of a motor. is disclosed.

JP 2017-191093 A

In the conventional technology described above, due to the provision of two circuits necessary for detecting the rotation of the motor, the size of the device increases and the cost of parts increases.

One aspect of the position detection device of the present invention is a position detection device that detects the rotational position of a motor, and is opposed to a magnet that rotates in synchronism with the motor and at predetermined intervals along the direction of rotation of the magnet. Three magnetic sensors are arranged, and a signal processing unit that processes three-phase signals output from the three magnetic sensors and having a phase difference of 120 degrees in electrical angle. The signal processing unit digitally converts each of the U-phase signal, the V-phase signal, and the W-phase signal included in the three-phase signals to obtain an instantaneous value Hu′ of the U-phase signal and an instantaneous value Hu′ of the V-phase signal. an acquisition process for acquiring the value Hv' and the instantaneous value Hw' of the W-phase signal; , the first case, the second case, and the third case, by determining whether or not the following expression (1) is satisfied, thereby identifying an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors. discrimination processing; signal generation processing for generating a remaining one-phase signal based on two-phase signals output from two of the three magnetic sensors excluding the abnormal sensor; and excluding the abnormal sensor. position estimation processing for estimating the rotational position of the motor based on the two-phase signals output from the two magnetic sensors and the generated remaining one-phase signal;

In one aspect of the position detection method of the present invention, three magnetic sensors facing a magnet rotating in synchronism with a motor and arranged at predetermined intervals along the direction of rotation of the magnet output an electrical angle to each other. A position detection method for detecting the rotational position of the motor using three-phase signals having a phase difference of 120° at , wherein the U-phase signal, the V-phase signal and the W-phase signal included in the three-phase signals an obtaining step of obtaining an instantaneous value Hu' of the U-phase signal, an instantaneous value Hv' of the V-phase signal, and an instantaneous value Hw' of the W-phase signal by digitally converting each of the above; Whether the instantaneous value Hu', the instantaneous value Hv' of the V-phase signal, and the instantaneous value Hw' of the W-phase signal satisfy the following expression (1) in all of the first case, the second case, and the third case an abnormality determination step of identifying an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors; a signal generation step of generating a remaining one-phase signal based on the phase signal; a two-phase signal output from two magnetic sensors excluding the abnormal sensor; and the generated remaining one-phase signal. and a position estimation step of estimating the rotational position of the motor based on.

According to the above aspect of the present invention, even if an abnormality occurs in one of the three magnetic sensors, the remaining magnetic sensor can remain based on the two-phase signals output from the two magnetic sensors excluding the abnormal sensor. A position detection device and a position detection method are provided that can continuously estimate the rotational position of a motor by generating a single-phase signal. Therefore, it is possible to reduce the size of the device and the cost of the parts compared to the conventional technology that prepares two circuits necessary for detecting the rotation of the motor.

FIG. 1 is a block diagram schematically showing the configuration of the position detection device according to this embodiment. FIG. 2 is a diagram showing a connection relationship among three magnetic sensors, a power supply circuit, and a processing section in this embodiment. FIG. 3 is a flowchart showing each process executed by the processing unit of the position detection device according to this embodiment. FIG. 4 is an explanatory diagram relating to abnormality determination processing executed by the processing unit of the position detection device according to the present embodiment. FIG. 5 is a flowchart showing signal generation processing executed by the processing unit of the position detection device according to this embodiment. FIG. 6 is a diagram representing the first signal Hu' and the second signal Hv' by rotating vectors on the complex plane. FIG. 7 shows the waveform data of the first signal Hu' obtained during one rotation of the vector of the first signal Hu' on the complex plane, and the waveform data of the second signal Hv' obtained during one rotation of the vector of the second signal Hv' on the complex plane. It is a figure which shows an example with the waveform data of 2nd signal Hv' obtained. FIG. 8 is a diagram showing a combined signal Huv of the first fundamental wave signal Hu and the second fundamental wave signal Hv as a rotating vector on the complex plane. FIG. 9 is a diagram showing an example of waveform data of the composite signal Huv obtained while the vectors of the first signal Hu' and the second signal Hv' make one rotation on the complex plane. FIG. 10 is an explanatory diagram of a method for calculating the phase difference φ1 between the first signal Hu' and the second signal Hv' in the learning process. FIG. 11 is an explanatory diagram relating to a method of calculating the phase difference φ2 between the combined signal Huv and the first signal Hu' in the learning process. FIG. 12 is an explanatory diagram showing that the phase difference between the combined signal Huv and the first fundamental wave signal Hu is equal to the phase difference φ2 between the combined signal Huv and the first signal Hu'. FIG. 13 is an explanatory diagram regarding the deflection angle ωt+φ2 of the composite signal Huv. FIG. 14 is a diagram showing the third fundamental wave signal Hw, which is orthogonal to the composite signal Huv, represented by a rotating vector on the complex plane. FIG. 15 is a diagram showing an example of waveform data of the third fundamental wave signal Hw obtained during one rotation of the vector of the combined signal Huv on the complex plane. FIG. 16 is a diagram showing an example of waveform data of the first fundamental wave signal Hu, waveform data of the second fundamental wave signal Hv, and waveform data of the third fundamental wave signal Hw. FIG. 17 is a first explanatory diagram relating to position estimation processing executed by the processing unit of the position detection device in this embodiment. FIG. 18 is a second explanatory diagram relating to position estimation processing executed by the processing unit of the position detection device in this embodiment.

An embodiment of the present invention will be described in detail below with reference to the drawings.
FIG. 1 is a block diagram schematically showing the configuration of a position detection device 1 according to one embodiment of the present invention. As shown in FIG. 1 , the position detection device 1 is a device that detects the rotational position (rotational angle) of the motor 100 . In this embodiment, the motor 100 is, for example, an inner rotor type three-phase brushless DC motor. Motor 100 has a rotor shaft 110 and a sensor magnet 120 . Rotor shaft 110 is the rotating shaft of motor 100 . The rotational position of motor 100 means the rotational position of rotor shaft 110 .

The sensor magnet 120 is a disc-shaped magnet attached to the rotor shaft 110 . Sensor magnet 120 is a magnet that rotates in synchronization with rotor shaft 110 . The sensor magnet 120 has P magnetic pole pairs (P is an integer equal to or greater than 2). In this embodiment, as an example, the sensor magnet 120 has four magnetic pole pairs. A magnetic pole pair means a pair of an N pole and an S pole. That is, in this embodiment, the sensor magnet 120 has four pairs of N poles and S poles, for a total of eight magnetic poles.

The position detection device 1 includes three

magnetic sensors

11 , 12 and 13 and a signal processing section 20 . Although not shown in FIG. 1, a circuit board is attached to the motor 100, and the three

magnetic sensors

11, 12 and 13 and the signal processing unit 20 are arranged on the circuit board. The sensor magnet 120 is arranged at a position that does not interfere with the circuit board. The sensor magnet 120 may be located inside the housing of the motor 100 or outside the housing.

The

magnetic sensors

11, 12 and 13 face the sensor magnet 120 on the circuit board and are arranged at predetermined intervals along the rotation direction CW of the sensor magnet 120. In this embodiment, the

magnetic sensors

11 , 12 and 13 are arranged at intervals of 30° along the rotation direction CW of the sensor magnet 120 . For example, the

magnetic sensors

11, 12 and 13 are analog output type magnetic sensors including magnetoresistive elements such as Hall elements or linear Hall ICs. The

magnetic sensors

11 , 12 and 13 each output an analog signal indicating the magnetic field strength that changes according to the rotational position of the rotor shaft 110 , that is, the rotational position of the sensor magnet 120 .

One cycle of the electrical angle of each analog signal output from the

magnetic sensors

11, 12 and 13 corresponds to 1/P of one cycle of the mechanical angle. In this embodiment, since the number of pole pairs P of the sensor magnet 120 is "4", one cycle of the electrical angle of each analog signal corresponds to 1/4 of one cycle of the mechanical angle, that is, 90° in mechanical angle. Also, the analog signals output from the

magnetic sensors

11, 12 and 13 have a phase difference of 120 electrical degrees from each other.

Hereinafter, the analog signal output from the magnetic sensor 11 will be referred to as the U-phase signal Hu', the analog signal output from the magnetic sensor 12 will be referred to as the V-phase signal Hv', and the analog signal output from the magnetic sensor 13 will be referred to. is called a W-phase signal Hw'. The V-phase signal Hv' has a phase lag of 120 electrical degrees with respect to the U-phase signal Hu'. The W-phase signal Hw' has a phase lag of 120 electrical degrees with respect to the V-phase signal Hv'.

As described above, the three

magnetic sensors

11, 12 and 13 output three-phase signals having a phase difference of 120 degrees in electrical angle. The magnetic sensor 11 outputs a U-phase signal Hu′ to the signal processing section 20 . The magnetic sensor 12 outputs a V-phase signal Hv′ to the signal processing section 20 . The magnetic sensor 13 outputs a W-phase signal Hw′ to the signal processing section 20 .

The signal processing unit 20 is a signal processing circuit that processes three-phase signals output from the three

magnetic sensors

11, 12, and 13 and having a phase difference of 120 degrees in electrical angle. Based on the U-phase signal Hu' output from the magnetic sensor 11, the V-phase signal Hv' output from the magnetic sensor 12, and the W-phase signal Hw' output from the magnetic sensor 13, the signal processing unit 20 , to estimate the rotational position of the motor 100 , that is, the rotational position of the rotor shaft 110 . The signal processing unit 20 includes a power supply circuit 21 , a processing unit 22 and a storage unit 23 .

The power supply circuit 21 is a circuit that converts an external power supply voltage supplied from a DC power supply 200 such as a battery into an internal power supply voltage required to operate the internal circuits of the signal processing section 20 . As an example, the external power supply voltage supplied from the DC power supply 200 is 5V, and the internal power supply voltage output from the power supply circuit 21 is 3.3V. For example, a low dropout regulator may be used as the power supply circuit 21 .

The power supply circuit 21 is electrically connected to the processing section 22 via the power supply line Vcc and the ground line GND. The power supply circuit 21 outputs the internal power supply voltage to the processing section 22 via the power supply line Vcc and the ground line GND. Although not shown in FIG. 1, the power supply circuit 21 is also electrically connected to the storage unit 23 via the power supply line Vcc and the ground line GND.

The processing unit 22 is, for example, a microprocessor such as an MCU (Microcontroller Unit). The U-phase signal Hu' output from the magnetic sensor 11, the V-phase signal Hv' output from the magnetic sensor 12, and the W-phase signal Hw' output from the magnetic sensor 13 are each input to the processing unit 22. be done. The processing unit 22 is communicably connected to the storage unit 23 via a communication bus (not shown). Although details will be described later, the processing unit 22 executes an acquisition process, an abnormality determination process, a signal generation process, and a position estimation process according to a program stored in advance in the storage unit 23 .

As shown in FIG. 2, the processing unit 22 has three output ports P1, P2 and P3. Output ports P1, P2 and P3 are, for example, CMOS output ports. The output port P1 is electrically connected to the magnetic sensor 11 via the sensor power supply line Vcc1. The output port P2 is electrically connected to the magnetic sensor 12 via the sensor power supply line Vcc2. The output port P3 is electrically connected to the magnetic sensor 13 via the sensor power supply line Vcc3. Incidentally, as shown in FIG. 2, the power supply circuit 21 is electrically connected to each of the

magnetic sensors

11, 12 and 13 via the ground line GND.

The processing unit 22 outputs a high-level voltage from the output port P1 to the magnetic sensor 11 as a sensor power supply voltage. The processing unit 22 outputs a high-level voltage to the magnetic sensor 12 from the output port P2 as a sensor power supply voltage. The processing unit 22 outputs a high-level voltage as a sensor power supply voltage from the output port P3 to the magnetic sensor 13 . For example, when the internal power supply voltage generated by the power supply circuit 21 is 3.3V, the high level voltage is 3.3V.

When cutting off the power supply to the magnetic sensor 11, the processing unit 22 switches the output voltage of the output port P1 to low level. When cutting off the power supply to the magnetic sensor 12, the processing unit 22 switches the output voltage of the output port P2 to low level. When cutting off the power supply to the magnetic sensor 13, the processing unit 22 switches the output voltage of the output port P3 to low level.

The storage unit 23 is used as a non-volatile memory for storing programs and various setting data necessary for the processing unit 22 to execute various processes, and as a temporary storage destination for data when the processing unit 22 executes various processes. and volatile memory. The nonvolatile memory is, for example, EEPROM (Electrically Erasable Programmable Read-Only Memory) or flash memory. Volatile memory is, for example, RAM (Random Access Memory).

Next, the acquisition process, abnormality determination process, signal generation process, and position estimation process executed by the processing unit 22 will be described.

When the power supply circuit 21 outputs the internal power supply voltage to the processing unit 22, the processing unit 22 is activated, performs a predetermined initialization process, and then outputs a high level voltage from each of the output ports P1, P2, and P3. As a result, the sensor power supply voltage is supplied to each of the three

magnetic sensors

11, 12 and 13, and each of the

magnetic sensors

11, 12 and 13 becomes ready to detect the magnetic field intensity.

As shown in FIG. 3, after starting power supply to each of the

magnetic sensors

11, 12 and 13, the processing unit 22 controls the U By digitally converting each of the phase signal Hu', the V-phase signal Hv', and the W-phase signal Hw', the instantaneous value of the U-phase signal Hu', the instantaneous value of the V-phase signal Hv', and the instantaneous value of the W-phase signal Hw' are obtained. Acquisition processing for acquiring a value is executed (step S1). This step S1 corresponds to an acquisition step.

Specifically, the processing unit 22 incorporates an A/D converter, and the processing unit 22 converts the U-phase signal Hu', the V-phase signal Hv', and the W-phase signal Hw' by the A/D converter. By digitally converting each at a predetermined sampling frequency, the instantaneous value of the U-phase signal Hu', the instantaneous value of the V-phase signal Hv', and the instantaneous value of the W-phase signal Hw' are obtained as digital values.

Then, the processing unit 22 determines that the instantaneous value of the U-phase signal Hu', the instantaneous value of the V-phase signal Hv', and the instantaneous value of the W-phase signal Hw' are lower in all of the first case, the second case, and the third case. By determining whether or not the expression (1) is satisfied, an abnormality determination process is executed to identify an abnormal sensor, which is an abnormal magnetic sensor, among the three

magnetic sensors

11, 12 and 13 (step S2). This step S2 corresponds to an abnormality determination step.

In the above formula (1), the minimum threshold THmin and the maximum threshold THmax are learning values obtained by the first learning process performed in advance and stored in the non-volatile memory of the storage unit 23 in advance. The first learning process will be described below.

FIG. 4 shows time-series data of instantaneous values of the U-phase signal Hu' (waveform data of the U-phase signal Hu') and the V-phase signal obtained when all three

magnetic sensors

11, 12 and 13 are normal. Examples of time-series data of instantaneous values of Hv' (waveform data of V-phase signal Hv') and time-series data of instantaneous values of W-phase signal Hw' (waveform data of W-phase signal Hw') are shown. In FIG. 4, the horizontal axis indicates time, and the vertical axis indicates digital values.

In the first learning process, the processing unit 22 calculates the three-phase unbalance component A maximum value Nzpn1 and a minimum value Nzpn2 of Nzpn (=Hu'+Hv'+Hw') are calculated. Then, the processing unit 22 sets the value obtained by adding the set value Δth, which is the design margin, to the maximum value Nzpn1 of the three-phase unbalanced component, as the maximum threshold value THmax (=Nzpn1+Δth) in the nonvolatile memory of the storage unit 23. store in The processing unit 22 also stores a value obtained by subtracting the set value Δth from the minimum value Nzpn2 of the three-phase unbalanced component in the non-volatile memory of the storage unit 23 as the minimum threshold THmin (=Nzpn2−Δth).

The above is the description of the first learning process. In step S2, the processing unit 22 reads the maximum threshold THmax and the minimum threshold THmin from the nonvolatile memory of the storage unit 23, and the instantaneous values of the three-phase signals obtained in step S1 are the first case, the second case, and the third case. An abnormal sensor is identified from among the three

magnetic sensors

11, 12 and 13 by determining whether or not expression (1) is satisfied in all cases.

As shown in FIG. 4, for example, when the magnetic sensor 13 is in a short-to-power state, the instantaneous value of the W-phase signal Hw' output from the magnetic sensor 13 is fixed to a digital value indicating a high level (eg, 3.3 V). be done. For example, when the magnetic sensor 13 is grounded, the instantaneous value of the W-phase signal Hw' output from the magnetic sensor 13 is fixed to a digital value indicating a low level (for example, 0V). For example, when the magnetic sensor 13 is in a failure state, the waveform data of the W-phase signal Hw' output from the magnetic sensor 13 shows an abnormal digital value different from the normal waveform data.

As described above, for example, when the magnetic sensor 13 is in an abnormal state, Equation (1) is not satisfied in the first case. The processing unit 22 identifies the magnetic sensor 13 as an abnormal sensor when the formula (1) is not satisfied in the first case. Similarly, when the magnetic sensor 11 is in an abnormal state, Equation (1) is not satisfied in the second case. The processing unit 22 identifies the magnetic sensor 11 as an abnormal sensor when the formula (1) is not satisfied in the second case. Also, when the magnetic sensor 12 is in an abnormal state, the formula (1) is not satisfied in the third case. The processing unit 22 identifies the magnetic sensor 12 as an abnormal sensor when the formula (1) is not satisfied in the third case.

When the abnormal sensor is identified by the abnormality determination process in step S2, the processing unit 22 cuts off the power supply to the abnormal sensor among the three

magnetic sensors

11, 12 and 13. For example, when the magnetic sensor 11 is an abnormal sensor, the processing unit 22 cuts off the power supply to the magnetic sensor 11 by switching the output voltage of the output port P1 to low level. When the magnetic sensor 12 is an abnormal sensor, the processing unit 22 cuts off the power supply to the magnetic sensor 12 by switching the output voltage of the output port P2 to low level. When the magnetic sensor 13 is an abnormal sensor, the processing unit 22 cuts off the power supply to the magnetic sensor 13 by switching the output voltage of the output port P3 to low level.

Then, the processing unit 22 performs signal generation processing for generating the remaining one-phase signal based on the two-phase signals output from two of the three

magnetic sensors

11, 12, and 13 excluding the abnormal sensor. Execute (step S3). This step S3 corresponds to a signal generation step. In the following description, one of the two-phase signals output from the two magnetic sensors excluding the abnormal sensor is defined as the first signal, and the other signal having a phase delay of 120° in electrical angle with respect to the first signal. is the second signal. For example, when the magnetic sensor 13 is an abnormal sensor, the U-phase signal Hu' output from the magnetic sensor 11 is the first signal, and the V-phase signal Hv' output from the magnetic sensor 12 is the second signal.

When the sensor magnet 120 rotates together with the rotor shaft 110, the magnetic sensor 11 outputs a first signal Hu' indicating the magnetic field intensity that changes according to the rotational position of the sensor magnet 120. A second signal Hv′ with a phase delay of 120° is output from the magnetic sensor 12 . The processing unit 22 digitally converts the first signal Hu' and the second signal Hv' at a predetermined sampling frequency using an A/D converter. The processing unit 22 executes the signal generation processing shown in the flowchart of FIG. 5 each time the execution timing of digital conversion, that is, the sampling timing arrives.

As shown in FIG. 5, when the sampling timing arrives, the processing unit 22 digitally converts the first signal Hu' and the second signal Hv' output to the processing unit 22 as the sensor magnet 120 rotates as described above. By converting, the instantaneous value of the first signal Hu' and the instantaneous value of the second signal Hv' are obtained as digital values (step S11). This step S11 corresponds to the first step, and the process executed in step S11 corresponds to the first process.

FIG. 6 is a diagram representing the first signal Hu' and the second signal Hv' by rotating vectors on the complex plane. In FIG. 6, the horizontal axis is the real number axis and the vertical axis is the imaginary number axis. The first signal Hu' and the second signal Hv' rotate at an angular velocity ω in the direction of the arrow on the complex plane. As shown in FIG. 6, the first signal Hu' includes the first fundamental wave signal Hu, which is a fundamental wave signal, and the in-phase signal N. As shown in FIG. The first signal Hu' is represented by a combined vector of the first fundamental wave signal Hu and the in-phase signal N. As shown in FIG. That is, the first signal Hu' is represented by the following equation (2). The second signal Hv' includes the second fundamental wave signal Hv, which is a fundamental wave signal, and the in-phase signal N. The second signal Hv' is represented by a composite vector of the second fundamental wave signal Hv and the in-phase signal N. That is, the second signal Hv' is represented by the following equation (3). In-phase signal N is a noise signal including a DC signal, a third harmonic signal, and the like.

The instantaneous value of the first signal Hu' obtained in step S11 corresponds to the real part (the part projected onto the real axis) of the first signal Hu' represented by the vector in FIG. Similarly, the instantaneous value of the second signal Hv' obtained in step S11 corresponds to the real part of the second signal Hv' represented by the vector in FIG. For example, the instantaneous value of the first signal Hu' is represented by the following equation (4). In the following equation (4), ||Hu'|| is the norm of the first signal Hu', and k is an integer of 1 or more.

FIG. 7 shows time-series data (waveform data of the first signal Hu') of instantaneous values of the first signal Hu' obtained during one rotation of the vector of the first signal Hu' on the complex plane, and 10 is a diagram showing an example of time-series data (waveform data of the second signal Hv') of instantaneous values of the second signal Hv' obtained while the vector of the second signal Hv' rotates once in FIG. In FIG. 7, the horizontal axis indicates time, and the vertical axis indicates digital values. As shown in FIG. 7, the waveforms of the first signal Hu' and the second signal Hv', which include the in-phase signal N, do not become perfectly sinusoidal waveforms, but become distorted waveforms.

Returning to FIG. 5, the processing unit 22 subtracts the instantaneous value of the second signal Hv' from the instantaneous value of the first signal Hu' to obtain the first fundamental wave signal Hu included in the first signal Hu' and the second fundamental wave signal Hu'. The instantaneous value of the combined signal Huv with the second fundamental wave signal Hv included in the signal Hv' is calculated (step S12). This step S12 corresponds to the second step, and the process executed in step S12 corresponds to the second process.

As shown in the following equation (5), by subtracting the instantaneous value of the second signal Hv' from the instantaneous value of the first signal Hu', the in-phase signal N contained in both signals is canceled, and the first fundamental wave It can be seen that the instantaneous value of the combined signal Huv of the signal Hu and the second fundamental wave signal Hv can be obtained. FIG. 8 is a diagram showing a combined signal Huv of the first fundamental wave signal Hu and the second fundamental wave signal Hv as a rotating vector on the complex plane. FIG. 9 shows an example of time-series data (waveform data of the combined signal Huv) of instantaneous values of the combined signal Huv obtained while the vectors of the first signal Hu' and the second signal Hv' make one rotation on the complex plane. FIG. 4 is a diagram showing; As shown in FIG. 9, the waveform of the combined signal Huv is a complete sinusoidal waveform.

Note that in step S12, the processing unit 22 calculates the instantaneous value of the first signal Hu' and the instantaneous value of the second signal Hv' based on amplitude correction values prepared in advance before calculating the instantaneous value of the composite signal Huv. correct at least one of The amplitude correction value is a correction value that makes the amplitude value of the first signal Hu' equal to the amplitude value of the second signal Hv'. The amplitude correction value is one of learning values obtained by the second learning process performed in advance, and is stored in the non-volatile memory of the storage unit 23 in advance. That is, in step S12, the processing unit 22 reads the amplitude correction value from the nonvolatile memory of the storage unit 23, and based on the read amplitude correction value, the amplitude value of the first signal Hu' and the amplitude of the second signal Hv' At least one of the instantaneous value of the first signal Hu' and the instantaneous value of the second signal Hv' is corrected so that the values are equal to each other.

Returning to FIG. 5, the processing unit 22 calculates the argument of the synthesized signal Huv based on the instantaneous value of the synthesized signal Huv and the prepared norm of the synthesized signal Huv (step S13). This step S13 corresponds to the third step, and the process executed in step S13 corresponds to the third process.

The norm of the synthesized signal Huv is one of the learning values obtained by the second learning process performed in advance, similarly to the amplitude correction value described above, and is stored in the non-volatile memory of the storage unit 23 in advance. In addition to the amplitude correction value and the norm of the combined signal Huv, the phase difference between the combined signal Huv and the first fundamental wave signal Hu is also stored in advance in the non-volatile memory of the storage unit 23 as a learned value. The second learning process performed in advance will be described below.

The second learning process is performed while the rotor shaft 110 and the sensor magnet 120 are rotating. In the second learning process, the processing unit 22 keeps the sensor magnet 120 at least until the time corresponding to one cycle of the electrical angle of the first signal Hu' and the second signal Hv' elapses, that is, at least the sensor magnet 120 is rotated by 90 degrees in mechanical angle. The above steps S11 and S12 are repeated at a predetermined sampling frequency until the rotation occurs. In other words, the processing unit 22 repeats the above steps S11 and S12 at a predetermined sampling frequency until the vectors of the first signal Hu' and the second signal Hv' rotate at least once on the complex plane.

As a result, the processing unit 31 sequentially acquires the instantaneous value of the first signal Hu′, the instantaneous value of the second signal Hv′, and the instantaneous value of the synthesized signal Huv, and obtains the maximum value of each past instantaneous value and the current value. Compare each instantaneous value with the time (current sampling timing), and if each instantaneous value at the current time is greater than the maximum value of the past instantaneous values, the maximum value of the past instantaneous values will be Perform processing to update to the value. In addition, the processing unit 31 sequentially acquires the instantaneous value of the first signal Hu', the instantaneous value of the second signal Hv', and the instantaneous value of the composite signal Huv, and calculates the minimum value of the past instantaneous values and the current time. If each instantaneous value of the current time is smaller than the minimum value of the past instantaneous values, update the minimum value of the past instantaneous values to the instantaneous value of the current time. .

The processing unit 22 acquires the maximum and minimum values of each signal by performing the sequential updating process as described above. Then, the processing unit 22 substitutes the maximum value Max(Hu') and the minimum value Min(Hu') of the first signal Hu' into the following equation (6) to obtain the amplitude value of the first signal Hu' Calculate the norm ||Hu'||. The processing unit 22 substitutes the maximum value Max(Hv') and the minimum value Min(Hv') of the second signal Hv' into the following equation (7) to obtain the norm | |Hv'|| is calculated. The processing unit 22 calculates the norm ||Huv||, which is the amplitude value of the combined signal Huv, by substituting the maximum value Max(Huv) and the minimum value Min(Huv) of the combined signal Huv into the following equation (8). do.

The processing unit 22 calculates an amplitude correction value that makes the norm ||Hu'|| of the first signal Hu' equal to the norm ||Hv'|| of the second signal Hv'. The processing unit 22 corrects at least one of all instantaneous values included in the waveform data of the first signal Hu' and all instantaneous values included in the waveform data of the second signal Hv' with the amplitude correction value. As a result, the waveform data of the first signal Hu' and the waveform data of the second signal Hv' having the same amplitude value (norm) are obtained.

As shown in FIG. 10, the processing unit 22 calculates the first signal Hu' based on the amplitude-corrected waveform data of the first signal Hu' and the waveform data of the second signal Hv'. A phase difference φ1 (≈typ.-120°) between Hu' and the second signal Hv' is calculated. Specifically, as shown in FIG. 10, the processing unit 22 determines the time between the maximum value Max (Hu') of the first signal Hu' and the maximum value Max (Hv') of the second signal Hv'. The phase difference φ1 is calculated by counting with a reference encoder or the like and substituting the count result Nmax into the following equation (9). Alternatively, the processing unit 22 counts the time between the minimum value Min (Hu') of the first signal Hu' and the minimum value Min (Hv') of the second signal Hv' using a reference encoder or the like, and the count result Nmin may be substituted into the following equation (10) to calculate the phase difference φ1. In equations (9) and (10), Ncpr is the resolution of the reference encoder. Note that in the second learning process, the reference encoder is attached in advance to the rotating shaft.

As shown in FIG. 11, the processing unit 22 calculates the phase difference φ2 (≈typ. +30°). Specifically, the processing unit 22 substitutes the phase difference φ1 between the first signal Hu′ and the second signal Hv′ into the following equation (11) to obtain the phase difference between the combined signal Huv and the first signal Hu′. A phase difference φ2 is calculated.

As shown in FIG. 12, the phase difference φ2 between the combined signal Huv and the first signal Hu' is equal to the phase difference between the combined signal Huv and the first fundamental wave signal Hu. Therefore, the processing unit 22 acquires the phase difference φ2 between the combined signal Huv and the first signal Hu' as the phase difference between the combined signal Huv and the first fundamental wave signal Hu. By the second learning process as described above, the amplitude correction value, the norm ||Huv|| of the synthesized signal Huv, and the phase difference φ2 between the synthesized signal Huv and the first fundamental wave signal Hu are obtained as learned values. . The processing unit 22 stores each learning value obtained by the second learning process in the nonvolatile memory of the storage unit 23 .

The above is the description of the second learning process. Returning to FIG. 5, the description of the signal generation process is continued below. In step S13 of FIG. 5, the processing unit 22 performs the calculation based on the instantaneous value of the combined signal Huv calculated in step S12 and the norm ||Huv|| of the combined signal Huv previously obtained by the second learning process. to calculate the deflection angle of the combined signal Huv. As shown in FIG. 13, the instantaneous value of the combined signal Huv is given by the following equation (12), where ωt+φ2 is the argument of the combined signal Huv.

Therefore, in step S13, the processing unit 22 calculates the argument ωt+φ2 of the synthesized signal Huv based on the following equation (13). That is, the processing unit 22 reads the norm ||Huv|| of the combined signal Huv from the nonvolatile memory of the storage unit 23, and combines By substituting the instantaneous value of Huv into the following equation (13), the argument ωt+φ2 of the combined signal Huv is calculated.

However, the argument ωt+φ2 of the synthesized signal Huv obtained by Equation (13) is limited to a value of 0° or more and 180° or less. Therefore, the sine value of the argument ωt+φ2 is limited to a positive value of 0 or more and 1 or less. Therefore, in the present embodiment, the processing unit 22 obtains the argument θ included in the range of −180° or more and less than 180° by expanding the calculated argument ωt+φ2. As a result, the sine value of the argument θ can take both positive and negative values within the range of −1 or more and 1 or less.

Then, the processing unit 22 determines the angle θ of the combined signal Huv, the norm ||Huv|| of the combined signal Huv, and the phase difference φ2 between the combined signal Huv and the first fundamental wave signal Hu prepared in advance. Then, the instantaneous value of the third fundamental wave signal Hw, which is orthogonal to the combined signal Huv, is calculated (step S14). This step S14 corresponds to the fourth step, and the process executed in step S14 corresponds to the fourth process.

FIG. 14 is a diagram showing the third fundamental wave signal Hw, which is in an orthogonal relationship with the composite signal Huv, represented by a rotating vector on the complex plane. When the condition that the amplitude value (||Hu'||) of the first signal Hu' and the amplitude value (||Hv'||) of the second signal Hv' are equal to each other is satisfied by the amplitude correction, the first basic The amplitude value (||Hu||) of the wave signal Hu and the amplitude value (||Hv||) of the second fundamental wave signal Hv become equal. In this case, the ratio between the norm ||Huv|| of the combined signal Huv and the norm ||Hw|| of the third fundamental wave signal Hw is ½ sin (φ2). Therefore, the instantaneous value of the third fundamental wave signal Hw, which is orthogonal to the combined signal Huv, is represented by the following equation (14).

In step S14, the processing unit 22 reads out the norm ||Huv|| of the combined signal Huv and the phase difference φ2 from the non-volatile memory of the storage unit 23, and the argument θ obtained in step S13 into the following equation (14), the instantaneous value of the third fundamental wave signal Hw is calculated. FIG. 15 is a diagram showing an example of time-series data (waveform data of the third fundamental wave signal Hw) of instantaneous values of the third fundamental wave signal Hw obtained while the vector of the combined signal Huv rotates once on the complex plane. is. As shown in FIG. 15, the waveform of the third fundamental signal Hw is a complete sinusoidal waveform like the waveforms of the combined signal Huv, the first fundamental signal Hu and the second fundamental signal Hv.

Returning to FIG. 5, the processing unit 22 calculates the first signal Hu' and the An instantaneous value of the in-phase signal N included in the second signal Hv' is calculated (step S15). This step S15 corresponds to the fifth step, and the process executed in step S15 corresponds to the fifth process. Specifically, in step S15, the processing unit 22 calculates the instantaneous value of the in-phase signal N based on the following equations (15) and (16).

In step S15, the processing unit 22 first substitutes the instantaneous value of the first signal Hu' and the instantaneous value of the second signal Hv' into the above equation (15) to obtain the instantaneous value of the third signal Hw'. calculate. The third signal Hw' is a signal that satisfies the three-phase balanced equation (Hu'+Hv'+Hw'=0) together with the first signal Hu' and the second signal Hv'. In other words, the third signal Hw' has a phase delay of 240 degrees in electrical angle with respect to the first signal Hu' and a phase delay of 120 degrees in electrical angle with respect to the second signal Hv'. be.

As shown in FIG. 14, when the third signal Hw' is represented by a vector rotating on the complex plane, the third signal Hw' is represented by the vector of the third fundamental wave signal Hw and the negative 2 of the in-phase signal N. It is represented by a vector (Hw'=Hw-2N) obtained by synthesizing the double vector. Therefore, the in-phase signal N can be expressed by the above equation (16). In step S15, the processing unit 22 substitutes the instantaneous value of the third signal Hw' calculated by equation (15) and the instantaneous value of the third fundamental wave signal Hw calculated in step S14 into equation (16). to calculate the instantaneous value of the in-phase signal N. FIG. 15 shows an example of the waveform of the third signal Hw' and the waveform of the in-phase signal N. As shown in FIG.

Returning to FIG. 5, the processing unit 22 calculates the instantaneous value of the first fundamental wave signal Hu by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the first signal Hu' (step S16). This step S16 corresponds to the sixth step, and the process executed in step S16 corresponds to the sixth process. It can be easily understood that the instantaneous value of the first fundamental wave signal Hu can be calculated by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the first signal Hu' by referring to the equation (2). deaf.

Finally, the processing unit 22 calculates the instantaneous value of the second fundamental signal Hv by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the second signal Hv' (step S17). This step S17 corresponds to the seventh step, and the process executed in step S17 corresponds to the seventh process. It can be easily understood that the instantaneous value of the second fundamental signal Hv can be calculated by subtracting the instantaneous value of the in-phase signal N from the instantaneous value of the second signal Hv' by referring to equation (3). deaf.

The signal generation processing including the processing from step S11 to step S17 as described above is executed by the processing unit 22 each time the sampling timing arrives. As a result, as shown in FIG. 16, time-series data of the instantaneous value of the first fundamental wave signal Hu (waveform data of the first fundamental wave signal Hu) and time-series data of the instantaneous value of the second fundamental wave signal Hv ( waveform data of the second fundamental wave signal Hv) and time-series data of instantaneous values of the third fundamental wave signal Hw (waveform data of the third fundamental wave signal Hw). As shown in FIG. 16, the waveforms of the first fundamental signal Hu, the second fundamental signal Hv and the third fundamental signal Hw are complete sinusoidal waveforms. Also, the first fundamental wave signal Hu, the second fundamental wave signal Hv, and the third fundamental wave signal Hw have a phase difference of 120 degrees in electrical angle.

By the above-described signal generation processing, a phase difference of 120° in electrical angle is generated based on the two-phase signals output from two of the three

magnetic sensors

11, 12, and 13 excluding the abnormal sensor. can generate a three-phase fundamental wave signal with

Returning to FIG. 3, the processing unit 22 estimates the rotational position of the motor 100 based on the two-phase signals output from the two magnetic sensors excluding the abnormality sensor and the generated remaining one-phase signal. An estimation process is executed (step S4). That is, the processing unit 22 estimates the rotational position of the motor 100 based on the three-phase fundamental wave signals Hu, Hv, and Hw having a phase difference of 120 degrees in electrical angle. This step S4 corresponds to the position estimation step.

A third learning process is performed in advance in order to acquire the learning value necessary for estimating the rotational position of the motor 100 . The third learning process performed in advance will be described below. The third learning process is performed while all of the

magnetic sensors

11, 12 and 13 are normal.

In the third learning process, the processing unit 22 generates waveform data (instantaneous value time series data). Based on these three waveform data, the processing unit 22 determines the waveform data of the first fundamental wave signal Hu included in the U-phase signal Hu' and the waveform data of the second fundamental wave signal Hv included in the V-phase signal Hv'. Waveform data and waveform data of the third fundamental wave signal Hw included in the W-phase signal Hw' are calculated. Note that the equations (1) and (2) described in Japanese Patent No. 6233532 are examples of computational equations for extracting the fundamental wave signal from each of the three-phase signals output from the three

magnetic sensors

11, 12 and 13. ) and equation (3) can be used.

As shown in FIG. 17, the processing unit 22 uses the waveform data of the three fundamental wave signals Hu, Hv, and Hw to convert one period of the mechanical angle into a pole pair number representing the pole pair position of each of the four magnetic pole pairs. Each of the four pole pair regions is further divided into a plurality of sections, and a segment number representing the rotational position of the rotor shaft 110 is tied to each of the plurality of sections. .

In this embodiment, in order to estimate the rotational position of the rotor shaft 110, the four magnetic pole pairs of the sensor magnet 120 are assigned pole pair numbers representing the pole pair positions. For example, as shown in FIG. 1, the four pole pairs of the sensor magnet 120 are assigned pole pair numbers in the clockwise order "0", "1", "2", "3".

As shown in FIG. 17, the processing unit 22 divides one cycle of the mechanical angle into four pole pair regions based on the waveform data of the fundamental wave signals Hu, Hv, and Hw obtained in one cycle of the mechanical angle. In FIG. 17, the period from time t1 to time t5 corresponds to one mechanical angle cycle. In FIG. 17, "No. C" indicates the pole pair number.
The processing unit 22 divides the period from time t1 to time t2 in one cycle of the mechanical angle as pole pair regions linked to the pole pair number "0".
The processing unit 22 divides the period from time t2 to time t3 in one cycle of the mechanical angle as pole pair regions associated with the pole pair number "1".
The processing unit 22 divides the period from the time t3 to the time t4 in one cycle of the mechanical angle as a pole pair region associated with the pole pair number "2".
The processing unit 22 divides the period from time t4 to time t5 in one cycle of the mechanical angle as a pole pair region associated with the pole pair number "3".

As shown in FIG. 17, the processing unit 22 further divides each of the four pole pair regions into 12 sections based on the waveform data of the fundamental wave signals Hu, Hv and Hw obtained in one cycle of the mechanical angle. , and each of the 12 sections is associated with a segment number representing the rotational position of the rotor shaft 110 . In FIG. 17, "No. A" indicates the section number assigned to the section, and "No. B" indicates the segment number.

As shown in FIG. 17, section numbers "0" to "11" are assigned to the 12 sections included in each of the four pole pair regions. On the other hand, numbers that are continuous over the entire period of one cycle of the mechanical angle are linked to each section as segment numbers. Specifically, as shown in FIG. 17, in the pole pair region associated with the pole pair number “0”, segment numbers “0” to “11” are assigned to section numbers “0” to “11”. ” is linked. In the pole pair region linked to the pole pair number "1", the segment numbers "12" to "23" are linked to the section numbers "0" to "11". In the pole pair region linked to the pole pair number "2", the segment numbers "24" to "35" are linked to the section numbers "0" to "11". In the pole pair region linked to the pole pair number "3", the segment numbers "36" to "47" are linked to the section numbers "0" to "11".

FIG. 18 is an enlarged view of the fundamental wave signals Hu, Hv and Hw included in one pole pair region. A method of dividing the pole pair region into 12 sections will now be described with reference to FIG. In FIG. 18, the amplitude reference value is "0". In FIG. 18, the positive amplitude digital value represents, as an example, the digital value of the N-pole magnetic field strength. In addition, the negative amplitude digital value represents, for example, the digital value of the magnetic field strength of the south pole.

The processing unit 22 extracts zero cross points, which are points where the three fundamental wave signals Hu, Hv, and Hw included in each of the four pole pair regions cross the reference value "0". As shown in FIG. 18, the processing unit 22 extracts points P1, P3, P5, P7, P9, P11, and P13 as zero-crossing points.

Then, the processing unit 22 extracts intersection points at which the three fundamental wave signals Hu, Hv, and Hw included in each of the four pole pair regions intersect each other. As shown in FIG. 18, the processing unit 22 extracts points P2, P4, P6, P8, P10, and P12 as intersections. Then, the processing unit 22 determines a section between the zero-cross points and the intersection points adjacent to each other as a section.

As shown in FIG. 18, the processing unit 22 determines the section between the zero-cross point P1 and the intersection point P2 as the section to which the section number "0" is assigned.
The processing unit 22 determines the section between the intersection point P2 and the zero crossing point P3 as the section to which the section number "1" is assigned.
The processing unit 22 determines the section between the zero-crossing point P3 and the intersection point P4 as the section to which the section number "2" is assigned.
The processing unit 22 determines the section between the intersection point P4 and the zero crossing point P5 as the section to which the section number "3" is assigned.
The processing unit 22 determines the section between the zero-crossing point P5 and the intersection point P6 as the section to which the section number "4" is assigned.
The processing unit 22 determines the section between the intersection point P6 and the zero crossing point P7 as the section to which the section number "5" is assigned.

The processing unit 22 determines the section between the zero-crossing point P7 and the intersection point P8 as the section to which the section number "6" is assigned.
The processing unit 22 determines the section between the intersection point P8 and the zero crossing point P9 as the section to which the section number "7" is assigned.
The processing unit 22 determines the section between the zero-crossing point P9 and the intersection point P10 as the section to which the section number "8" is assigned.
The processing unit 22 determines the section between the intersection point P10 and the zero crossing point P11 as the section to which the section number "9" is assigned.
The processing unit 22 determines the section between the zero-crossing point P11 and the intersection point P12 as the section to which the section number "10" is assigned.
The processing unit 22 determines the section between the intersection point P12 and the zero crossing point P13 as the section to which the section number "11" is assigned.

Furthermore, the processing unit 22 extracts feature data, such as the magnitude relationship of the instantaneous values (digital values) of the fundamental wave signals Hu, Hv, and Hw, and the sign of each instantaneous value, for each section, and extracts the extracted feature data. Link to the section number of each section.

By executing the above processing, as shown in FIG. 17, one cycle of the mechanical angle is divided into four pole pair regions linked to the pole pair numbers, and each of the four pole pair regions has 12 It is divided into sections, and each section number is associated with a segment number. In the following description, for example, the section assigned section number "0" will be referred to as "0 section", and the section assigned section number "11" will be referred to as "11 section". .

The processing unit 22 uses, as learning data, data indicating the correspondence between the feature data associated with the section number, the segment number indicating the rotational position associated with the section number, and the pole pair number indicating the pole pair position. It acquires and stores the acquired learning data in the storage unit 23 . The above is the description of the third learning process.

In step S4, when starting the position estimation process, the processing unit 22 first selects the current section from among 12 sections based on the instantaneous values of the fundamental wave signals Hu, Hv, and Hw obtained in step S3. identify. For example, in FIG. 18, a point PHu located on the waveform of the first fundamental wave signal Hu, a point PHv located on the waveform of the second fundamental wave signal Hv, and a point located on the waveform of the third fundamental wave signal Hw. It is assumed that PHw is the instantaneous value of each of the fundamental wave signals Hu, Hv and Hw obtained at arbitrary sampling timings. The processing unit 22 extracts feature data such as the magnitude relationship of the instantaneous values of the point PHu, the point PHv, and the point PHw, and the positive and negative signs of each instantaneous value. , the section number associated with the feature data that matches the extracted feature data is identified as the current section. In the example of FIG. 18, section number 9 is identified as the current section.

Then, the processing unit 22 determines the current segment number as the rotational position of the motor 100 based on the identified current section (section number) and the learning data stored in the storage unit 23 . For example, assume section number 9 is identified as the current section, as described above. Also, assume that the pole pair number is "2" when the instantaneous values of the points PHu, PHv and PHw are obtained. In this case, as shown in FIG. 17, the processing unit 22 determines the segment number "33" as the rotation position of the motor 100. In this case, as shown in FIG.

As described above, the position detection device of this embodiment includes three magnetic sensors that face the magnet that rotates in synchronism with the motor and that are arranged at predetermined intervals along the direction of rotation of the magnet, and three magnetic sensors. and a signal processing unit for processing output three-phase signals having a phase difference of 120 electrical degrees from each other. The signal processing unit digitally converts each of the U-phase signal, the V-phase signal, and the W-phase signal included in the three-phase signals to obtain the instantaneous value Hu′ of the U-phase signal, the instantaneous value Hv′ of the V-phase signal, and the Acquisition processing for acquiring the instantaneous value Hw' of the W-phase signal, and the instantaneous value Hu' of the U-phase signal, the instantaneous value Hv' of the V-phase signal, and the instantaneous value Hw' of the W-phase signal are obtained in the first case and the second case. and an abnormality determination process for identifying an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors by determining whether expression (1) is satisfied in all of the third cases, and A signal generation process for generating a remaining one-phase signal based on two-phase signals output from two magnetic sensors excluding the abnormal sensor, and a two-phase signal output from the two magnetic sensors excluding the abnormal sensor. , and position estimation processing for estimating the rotational position of the motor based on the generated signal of the remaining one phase.
According to this embodiment, even if an abnormality occurs in one of the three magnetic sensors, based on the two-phase signals output from the two magnetic sensors other than the abnormal sensor, By generating the remaining one-phase signal, it is possible to continuously estimate the rotational position of the motor. Therefore, it is possible to reduce the size of the device and the cost of the parts compared to the conventional technology that prepares two circuits necessary for detecting the rotation of the motor.

Of the two-phase signals output from the two magnetic sensors excluding the abnormal sensor, one signal is defined as the first signal, and the other signal having a phase delay of 120 degrees in electrical angle with respect to the first signal is defined as the second signal. In the case of a signal, the signal processing unit of the present embodiment includes, in the signal generation processing, first processing for obtaining the instantaneous value of the first signal and the instantaneous value of the second signal, and obtaining the second signal from the instantaneous value of the first signal. second processing for calculating an instantaneous value of a composite signal of a first fundamental wave signal included in the first signal and a second fundamental wave signal included in the second signal by subtracting the instantaneous values of the signals; A third process of calculating the argument of the synthesized signal based on the instantaneous value of and the norm of the synthesized signal prepared in advance, the argument of the synthesized signal, the norm of the synthesized signal, the prepared synthesized signal and the third and a fourth process of calculating an instantaneous value of a third fundamental signal having an orthogonal relationship with the combined signal based on the phase difference from the first fundamental signal.
Thereby, a third phase signal (third fundamental wave signal) that does not include an in-phase signal is generated from two phase signals (first signal and second signal) obtained by the two magnetic sensors excluding the abnormal sensor. be able to.

In the third process, the signal processing unit of the present embodiment calculates the argument ωt+φ2 of the composite signal based on the equation (13), and expands the calculated argument ωt+φ2 to obtain a value of −180° or more and 180°. Get the angle of argument θ within the range of less than °.
As a result, the argument ωt+φ2 of the combined signal can be calculated from the instantaneous value and the norm of the combined signal using a simple formula with a small processing load. Note that when calculating the argument ωt+φ2 of the synthesized signal based on Equation (13), the argument ωt+φ2 of the synthesized signal may be calculated by interpolation processing using table values. Further, by expanding the calculated argument ωt+φ2 to obtain the argument θ included in the range of −180° or more and less than 180°, the sine value of the argument θ is −1 or more and 1 or less. can take both positive and negative values within the range of , the waveform of the third fundamental signal generated by the fourth processing can be a perfect sinusoidal waveform.

In the second process, the signal processing unit of the present embodiment calculates the instantaneous value of the first signal and At least one of the instantaneous value of the second signal is corrected, and in the fourth process, the signal processing unit converts the norm ||Huv|| By substituting, the instantaneous value of the third fundamental wave signal is calculated.
As a result, the moment of the third fundamental wave signal that is orthogonal to the combined signal can be obtained from the norm and argument of the combined signal and the phase difference between the combined signal and the first fundamental wave signal using a simple formula with a small processing load. value can be calculated.

The signal processing unit of the present embodiment includes fifth processing for calculating an instantaneous value of the in-phase signal based on the instantaneous value of the first signal, the instantaneous value of the second signal, and the instantaneous value of the third fundamental wave signal; A sixth process of calculating an instantaneous value of the first fundamental wave signal by subtracting the instantaneous value of the in-phase signal from the instantaneous value of the first signal, and subtracting the instantaneous value of the in-phase signal from the instantaneous value of the second signal. and a seventh process of calculating the instantaneous value of the second fundamental wave signal.
As a result, the first fundamental wave signal having a sinusoidal waveform can be extracted from the first signal, and the second fundamental wave signal having a sinusoidal waveform and a phase delay of 120 degrees in electrical angle with respect to the first fundamental wave signal can be extracted from the second signal. A fundamental signal can be extracted.

In the fifth process, the signal processing unit of this embodiment calculates the instantaneous value of the in-phase signal based on Equations (15) and (16).
As a result, the in-phase signal can be extracted from the first signal and the second signal using a simple formula with a small processing load.

The signal processing unit of this embodiment cuts off the power supply to the abnormal sensor among the three magnetic sensors.
By interrupting the power supply to the abnormality sensor in this way, the internal circuit of the position detection device can be protected.

(Modification)
The present invention is not limited to the above-described embodiments, and each configuration described in this specification can be appropriately combined within a mutually consistent range.

For example, in the above embodiment, the signal generation processing when the magnetic sensor 13 is an abnormal sensor has been described. That is, in the above embodiment, the signal generation processing is performed when the U-phase signal Hu' output from the magnetic sensor 11 is the first signal and the V-phase signal Hv' output from the magnetic sensor 12 is the second signal. explained. On the other hand, when the magnetic sensor 11 is an abnormal sensor, the V-phase signal Hv' output from the magnetic sensor 12 is used as the first signal, and the W-phase signal Hw' output from the magnetic sensor 13 is used as the second signal. A signal generation process can be performed as a signal. When the magnetic sensor 12 is an abnormal sensor, the W-phase signal Hw' output from the magnetic sensor 13 is used as the first signal, and the U-phase signal Hu' output from the magnetic sensor 11 is used as the second signal. A generation process can be performed.

In the above embodiment, the case where the power supply to the magnetic sensor 11 is cut off by the processing unit 22 switching the output voltage of the output port P1 to low level has been exemplified. In contrast, a configuration is adopted in which a buffer including a transistor is provided between the output port P1 and the magnetic sensor 11, and the power supply to the magnetic sensor 11 is cut off by controlling the buffer with the output voltage of the output port P1. You may The same is true for the

magnetic sensors

12 and 13 as well.

For example, in the above embodiments, the combination of the motor and the position detection device was exemplified, but the present invention is not limited to this form, and a combination of the sensor magnet attached to the rotating shaft and the position detection device is also possible.
In the above-described embodiment, the three magnetic sensors are arranged facing the disk-shaped sensor magnet in the axial direction of the rotating shaft, but the present invention is not limited to this configuration. For example, when a ring-shaped magnet is used instead of a disk-shaped sensor magnet, the magnetic flux flows in the radial direction of the ring-shaped magnet, so the three magnetic sensors face the ring-shaped magnet in the radial direction of the ring-shaped magnet. It may be placed in a state where
In the above embodiment, the sensor magnet 120 attached to the rotor shaft 110 of the motor 100 is used as the rotating magnet, but the rotor magnet attached to the rotor of the motor 100 may be used as the rotating magnet. . The rotor magnet is also a magnet that rotates in synchronization with the rotor shaft 110 .

In the above embodiment, the sensor magnet 120 has four magnetic pole pairs, but the number of pole pairs of the sensor magnet 120 is not limited to four. Similarly, when a rotor magnet is used as the rotating magnet, the number of pole pairs of the rotor magnet is not limited to four.

DESCRIPTION OF SYMBOLS 1...

Position detection apparatus

11, 12, 13... Magnetic sensor, 20... Signal processing part, 21... Power supply circuit, 22... Processing part, 23... Storage part, 100... Motor, 110... Rotor shaft, 120... Sensor magnet ( magnet), 200... DC power supply

Claims

A position detection device that detects the rotational position of a motor,
three magnetic sensors facing the magnet rotating in synchronism with the motor and arranged at predetermined intervals along the direction of rotation of the magnet;
a signal processing unit that processes three-phase signals output from the three magnetic sensors and having a phase difference of 120 degrees in electrical angle;
with
The signal processing unit is
By digitally converting each of the U-phase signal, the V-phase signal, and the W-phase signal included in the three-phase signals, the instantaneous value Hu' of the U-phase signal, the instantaneous value Hv' of the V-phase signal, and the W-phase signal are obtained. Acquisition processing for acquiring the instantaneous value Hw′ of the phase signal;
The instantaneous value Hu' of the U-phase signal, the instantaneous value Hv' of the V-phase signal, and the instantaneous value Hw' of the W-phase signal are expressed by the following equation (1) in all of the first case, the second case, and the third case. Abnormality determination processing for identifying an abnormal sensor that is an abnormal magnetic sensor among the three magnetic sensors by determining whether or not the condition is satisfied;
A signal generation process for generating a remaining one-phase signal based on the two-phase signals output from two of the three magnetic sensors excluding the abnormal sensor;
position estimation processing for estimating the rotational position of the motor based on the two-phase signals output from the two magnetic sensors excluding the abnormal sensor and the generated remaining one-phase signal; Position detection device.
Of the two-phase signals output from the two magnetic sensors excluding the abnormal sensor, one signal is defined as the first signal, and the other signal having a phase delay of 120 degrees in electrical angle with respect to the first signal is defined as the first signal. In the case of the second signal,
The signal processing unit, in the signal generation process,
a first process of obtaining an instantaneous value of the first signal and an instantaneous value of the second signal by digitally converting the first signal and the second signal;
A synthesized signal of a first fundamental signal contained in the first signal and a second fundamental signal contained in the second signal by subtracting the instantaneous value of the second signal from the instantaneous value of the first signal a second process of calculating an instantaneous value of
a third process of calculating the argument of the synthesized signal based on the instantaneous value of the synthesized signal and the norm of the synthesized signal prepared in advance;
A third fundamental wave having an orthogonal relationship with the combined signal based on the argument of the combined signal, the norm of the combined signal, and a phase difference between the combined signal and the first fundamental wave signal prepared in advance. a fourth process of calculating the instantaneous value of the signal as the instantaneous value of the signal of the remaining one phase;
The position detection device according to claim 1, wherein:
When the argument of the synthesized signal is ωt+φ2, the instantaneous value of the synthesized signal is Huv, and the norm of the synthesized signal is ||Huv||
In the third processing, the signal processing unit calculates the argument ωt+φ2 of the synthesized signal based on the following equation (13), and performs an expansion process on the calculated argument ωt+φ2 to obtain a value of −180° or more and 180°. 3. The position detection device according to claim 2, wherein the angle of argument θ included in a range of less than degrees is acquired.
When the phase difference between the synthesized signal and the first fundamental wave signal is φ2, and the instantaneous value of the third fundamental wave signal is Hw,
In the second processing, the signal processing unit calculates the instantaneous value of the first signal based on an amplitude correction value prepared in advance that makes the amplitude value of the first signal equal to the amplitude value of the second signal. and the instantaneous value of the second signal, and
In the fourth processing, the signal processing unit substitutes the norm ||Huv|| of the combined signal, the phase difference φ2, and the argument θ into the following equation (14), thereby performing the third 4. The position detection device according to claim 3, which calculates an instantaneous value of the fundamental wave signal.
The signal processing unit, in the signal generation process,
an instantaneous value of an in-phase signal included in the first signal and the second signal based on an instantaneous value of the first signal, an instantaneous value of the second signal, and an instantaneous value of the third fundamental signal; a fifth process of calculating
a sixth process of calculating an instantaneous value of the first fundamental signal by subtracting an instantaneous value of the in-phase signal from an instantaneous value of the first signal;
a seventh process of calculating an instantaneous value of the second fundamental wave signal by subtracting an instantaneous value of the in-phase signal from an instantaneous value of the second signal;
5. The position detection device according to any one of claims 2 to 4, further performing:
Let Hu' be the instantaneous value of the first signal, Hv' be the instantaneous value of the second signal, Hw be the instantaneous value of the third fundamental signal, and N be the instantaneous value of the in-phase signal. ,
6. The position detection device according to claim 5, wherein in said fifth processing, said signal processing unit calculates the instantaneous value of said in-phase signal based on the following equations (15) and (16).
The position detection device according to any one of claims 1 to 6, wherein the signal processing unit cuts off power supply to the abnormality sensor among the three magnetic sensors.
Three-phase signals having a phase difference of 120° in electrical angle from each other, which are output from three magnetic sensors that face a magnet that rotates in synchronism with a motor and that are arranged at predetermined intervals along the direction of rotation of the magnet. A position detection method for detecting the rotational position of the motor using
By digitally converting each of the U-phase signal, the V-phase signal, and the W-phase signal included in the three-phase signals, the instantaneous value Hu' of the U-phase signal, the instantaneous value Hv' of the V-phase signal, and the W-phase signal are obtained. an acquisition step of acquiring an instantaneous value Hw' of the phase signal;
The instantaneous value Hu' of the U-phase signal, the instantaneous value Hv' of the V-phase signal, and the instantaneous value Hw' of the W-phase signal are expressed by the following equation (1) in all of the first case, the second case, and the third case. an abnormality determination step of identifying an abnormal sensor, which is an abnormal magnetic sensor among the three magnetic sensors, by determining whether or not the conditions are satisfied;
a signal generation step of generating a remaining one-phase signal based on two-phase signals output from two of the three magnetic sensors excluding the abnormal sensor;
a position estimation step of estimating the rotational position of the motor based on the two-phase signals output from the two magnetic sensors excluding the abnormality sensor and the generated remaining one-phase signal; Detection method.
Of the two-phase signals output from the two magnetic sensors excluding the abnormal sensor, one signal is defined as the first signal, and the other signal having a phase delay of 120 degrees in electrical angle with respect to the first signal is defined as the first signal. In the case of the second signal,
The signal generation step includes:
a first step of obtaining an instantaneous value of the first signal and an instantaneous value of the second signal by digitally converting the first signal and the second signal;
A synthesized signal of a first fundamental signal contained in the first signal and a second fundamental signal contained in the second signal by subtracting the instantaneous value of the second signal from the instantaneous value of the first signal a second step of calculating the instantaneous value of
a third step of calculating the argument of the synthesized signal based on the instantaneous value of the synthesized signal and the norm of the synthesized signal prepared in advance;
A third fundamental wave having an orthogonal relationship with the combined signal based on the argument of the combined signal, the norm of the combined signal, and a phase difference between the combined signal and the first fundamental wave signal prepared in advance. a fourth step of calculating the instantaneous value of the signal as the instantaneous value of the remaining one-phase signal;
The position detection method according to claim 8, comprising:
When the argument of the synthesized signal is ωt+φ2, the instantaneous value of the synthesized signal is Huv, and the norm of the synthesized signal is ||Huv||
In the third step, the argument ωt+φ2 of the synthesized signal is calculated based on the following equation (13), and the calculated argument ωt+φ2 is expanded to be included in the range of −180° or more and less than 180°. 10. The position detection method according to claim 9, wherein the argument .theta.
When the phase difference between the synthesized signal and the first fundamental wave signal is φ2, and the instantaneous value of the third fundamental wave signal is Hw,
In the second step, the instantaneous value of the first signal and the value of the second signal are calculated based on an amplitude correction value prepared in advance that makes the amplitude value of the first signal equal to the amplitude value of the second signal. correcting at least one of the instantaneous value and
In the fourth step, by substituting the norm ||Huv|| of the synthesized signal, the phase difference φ2, and the argument θ into the following equation (14), the instantaneous value of the third fundamental wave signal 11. The position detection method according to claim 10, wherein calculating
The signal generation step includes:
an instantaneous value of an in-phase signal included in the first signal and the second signal based on an instantaneous value of the first signal, an instantaneous value of the second signal, and an instantaneous value of the third fundamental signal; a fifth step of calculating
a sixth step of calculating an instantaneous value of the first fundamental signal by subtracting an instantaneous value of the in-phase signal from an instantaneous value of the first signal;
a seventh step of calculating an instantaneous value of the second fundamental signal by subtracting an instantaneous value of the in-phase signal from an instantaneous value of the second signal;
The position detection method according to any one of claims 9 to 11, further comprising:
Let Hu' be the instantaneous value of the first signal, Hv' be the instantaneous value of the second signal, Hw be the instantaneous value of the third fundamental signal, and N be the instantaneous value of the in-phase signal. ,
13. The position detection method according to claim 12, wherein in said fifth step, the instantaneous value of said in-phase signal is calculated based on the following equations (15) and (16).
The position detection method according to any one of claims 8 to 13, further comprising a step of cutting off power supply to said abnormality sensor among said three magnetic sensors.