Brushless motor drive

Abstract

The present invention relates to a brushless motor drive device that is highly versatile and capable of reducing motor costs. According to one embodiment, the motor drive device comprises: an output unit that supplies an excitation current to an excitation coil that generates a magnetic field that rotates a rotor; a position detection unit that detects the rotational position of the rotor; and a drive control unit that generates a drive signal based on a detection signal from the position detection unit and supplies the drive signal to the output unit, wherein the position detection unit comprises: a first detection element that detects the rotational position of the rotor; a second detection element that detects the rotational position of the rotor before the first detection element; and a third detection element that follows the first detection element in detecting the rotational position of the rotor, wherein the first to third detection elements are integrated into one body.

Description

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2021-38557 (filing date: March 10, 2021), the entire contents of which are incorporated herein by reference. Technical Field

[0002] This embodiment relates to a brushless motor driving device. Background Art

[0003] In the past, the following technology for a three-phase brushless motor was disclosed: three sensors for detecting the rotational position of the rotor were arranged at positions with a phase difference of 120 degrees at electrical angles. Since three sensors were provided separately, the number of components increased. In addition, since three sensors were placed at positions with a phase difference of 120 degrees at electrical angles, a larger support base was required for placing the sensors, increasing the cost of the motor. Furthermore, the sensor configuration position needed to be adjusted for each motor, which was complicated. On the other hand, if only one sensor was provided, there was a risk of improper motor startup. A brushless motor drive device with high versatility and the ability to reduce motor costs is desired. Summary of the Invention

[0004] One embodiment provides a brushless motor drive device that has high versatility and can reduce motor costs.

[0005] According to one embodiment, a motor drive device includes: an output unit that supplies an excitation current to an excitation coil that generates a magnetic field to rotate a rotor; a position detection unit that detects the rotational position of the rotor; and a drive control unit that generates a drive signal based on a detection signal from the position detection unit and supplies the drive signal to the output unit, wherein the position detection unit includes: a first detection element that detects the rotational position of the rotor; a second detection element that detects the rotational position of the rotor before the first detection element; and a third detection element that follows the first detection element to detect the rotational position of the rotor, wherein the first to third detection elements are integrated into one. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a diagram schematically showing the circuit configuration of the brushless motor drive device according to the first embodiment.

[0007] Figure 2 This is a diagram schematically showing the arrangement relationship between a brushless motor drive device and a rotor.

[0008] Figure 3 This is a diagram for explaining a driving method of the brushless motor driving device.

[0009] Figure 4This is a diagram for explaining a method of generating a drive signal of a brushless motor drive device when the rotor rotates forward.

[0010] Figure 5 This is a diagram for explaining a method of generating a drive signal of a brushless motor drive device when the rotor rotates reversely.

[0011] Figure 6 This is a diagram for explaining a signal generation method when the phase difference is equal to or smaller than a threshold value.

[0012] Figure 7 This is a diagram for explaining in detail a signal generation method when the phase difference is equal to or smaller than a threshold value.

[0013] Figure 8 This is a diagram for explaining a signal generation method when the phase difference is larger than a threshold value.

[0014] Figure 9 This is a diagram for explaining in detail the signal generation method when the phase difference is larger than a threshold value.

[0015] Figure 10 This is a diagram for explaining the offset of the output signal of the auxiliary sensor and the signal generation method.

[0016] Figure 11 This is a diagram showing a flow of one embodiment of calibration.

[0017] Figure 12 This is a diagram showing an example of a planar pattern of an integrated brushless motor drive device.

[0018] Figure 13 This is an exploded perspective view of one embodiment of a motor with a built-in brushless motor drive device. DETAILED DESCRIPTION

[0019] Hereinafter, a brushless motor drive device according to an embodiment will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to these embodiments.

[0020] (First embodiment)

[0021] Figure 1 This figure schematically illustrates the circuit configuration of a brushless motor drive device 100 according to a first embodiment. The brushless motor drive device 100 according to this embodiment (hereinafter referred to as the drive device 100) includes a sensor unit 10. The sensor unit 10 includes a main sensor 11, an auxiliary sensor 12, and an auxiliary sensor 13. Each of the sensors 11, 12, and 13 is configured, for example, as a Hall element or as an integrated circuit including an amplifier circuit (not shown) that amplifies the output signal of the Hall element.

[0022] The Hall element of each sensor 11, 12, and 13 can be made of silicon or a compound semiconductor such as GaAs or InAs. If the Hall element is made of silicon, it can be integrated onto a single silicon substrate (not shown) along with other circuit components constituting the drive device 100. If the Hall element is made of a compound semiconductor, a single chip (not shown) having a Hall element made of a compound semiconductor and a silicon substrate having other circuit components can be integrated together using a multi-chip configuration. For example, the integration can be achieved by molding resin.

[0023] The drive device 100 of this embodiment includes a detection unit 20. The detection unit 20 includes an offset cancellation unit 21 to which the output signal of the main sensor 11 is supplied. The offset cancellation unit 21 can be configured, for example, to subtract the output signal obtained by changing the direction of the current supplied to the Hall element (not shown) of the main sensor 11. The output signal of the offset cancellation unit 21 is supplied to a comparator 22. The comparator 22 has, for example, a hysteresis characteristic and outputs a digital signal whose H level and L level change at a zero crossing. By providing the comparator 22 with a hysteresis characteristic, oscillation can be prevented.

[0024] The output signals of the auxiliary sensors 12 and 13 are supplied to comparators 23 and 24, respectively. Comparators 23 and 24 compare the output signals of the auxiliary sensors 12 and 13 with predetermined threshold values ​​and output digital signals that vary between high and low levels based on the comparison results. Comparators 23 and 24 are, for example, window comparators that compare two threshold voltages with the input signal and output a digital signal at either high or low levels based on the comparison results. The relationship between the threshold voltage settings supplied to comparators 23 and 24 and their output signals will be described later.

[0025] Detection unit 20 includes AD converter 25 to which the output of offset canceller 21 is supplied, and AD converters 26 and 27 to which the output signals of auxiliary sensors 12 and 13 are supplied. Each AD converter 25 to 27 converts the output signal of each sensor 11, 12, and 13 into a digital signal and outputs the digital signal.

[0026] The driving device 100 of the present embodiment includes a control unit 30 . The control unit 30 includes a signal processing unit 31 , a threshold voltage generating unit 32 , a phase difference detecting unit 33 , a sensor output selecting unit 34 , and a driving signal generating unit 35 .

[0027] The signal processing unit 31 performs predetermined arithmetic processing using the output signals of the AD converters 25 to 27. For example, the signal processing unit 31 performs arithmetic processing using the digital signals obtained from the AD converters 25 to 27 and supplies the processing results to the threshold voltage generating unit 32, the phase difference detecting unit 33, and the drive signal generating unit 35.

[0028] The drive device 100 of this embodiment includes a storage unit 50. The storage unit 50 stores the auxiliary sensor selection results obtained during calibration performed at motor startup, as well as the values ​​of the output signals of the auxiliary sensors 12 and 13. Furthermore, the storage unit 50 stores data on driving conditions during startup calibration. The drive signal generator 35 generates a drive signal for rotating the rotor 62 at a constant frequency (rotational speed) in response to a signal supplied at a predetermined timing from the storage unit 50 via the signal processor 31 during calibration, for example.

[0029] The threshold voltage generator 32 performs analog conversion on the digital signal supplied from the signal processor 31, generates threshold voltages for the comparators 23 and 24 based on the output signals of the AD converters 26 and 27 obtained in the calibration performed at motor startup, and supplies the generated threshold voltages to the comparators 23 and 24. Calibration will be described later.

[0030] The phase difference detection unit 33 detects the phase difference between the output signals of the sensors 11 , 12 , and 13 supplied from the signal processing unit 31 . The output signal of the phase difference detection unit 33 is supplied to the sensor output selection unit 34 via the signal processing unit 31 .

[0031] The sensor output selector 34 selects a signal to be supplied to the drive signal generator 35 in response to the output signal of the phase difference detector 33 supplied via the signal processor 31. When the phase difference between the output signal of the main sensor 11 and the output signal of the auxiliary sensor 12 during forward rotation of the rotor 62 is equal to or smaller than a predetermined threshold, the sensor output selector 34 selects the output signals from the main sensor 11 and the auxiliary sensor 12 and supplies them to the drive signal generator 35. The threshold is, for example, 30 degrees in electrical angle. The threshold and output signal selection method will be described later.

[0032] The drive signal generating unit 35 generates a drive signal using the signal supplied from the sensor output selecting unit 34 , and supplies the drive signal to the output circuit unit 40 .

[0033] The output circuit unit 40 has output transistors 41 to 46. Each output transistor 41 to 46 has a freewheeling diode 411 to 416 between the source and the drain. Each output transistor 41 to 46 of the output circuit unit 40 forms a bridge circuit, and responds to the drive signal from the drive signal generating unit 35, for example, by conducting 120 degrees of power. Each output transistor 41 to 46 supplies an excitation current to the excitation coils LU, LV, LW of the coil unit 61 of the motor 60 via the output lines 301 to 303. The excitation coils LU, LV, LW are excited by the excitation current and generate a magnetic field. The rotor 62 composed of permanent magnets rotates according to the magnetic field generated by the excitation coils LU, LV, LW. In addition, the excitation coils LU, LV, LW can also be connected in a delta connection. The drive device 100 having the sensor unit 10 is arranged at a position close to the rotor 62 of the motor 60.

[0034] In the drive device 100 of the first embodiment, the main sensor 11, the auxiliary sensor 12, and the auxiliary sensor 13 are integrally integrated. Furthermore, the drive device 100 stores the selection results of the auxiliary sensors 12 and 13 and the values ​​of the output signals of the auxiliary sensors 12 and 13 obtained during calibration in the storage unit 50, and the threshold voltage generator 32 sets the threshold voltages of the comparators 23 and 24. Therefore, the threshold voltage setting value can be changed for each motor equipped with the drive device 100, resulting in a highly versatile configuration.

[0035] Figure 2 Schematically shows the arrangement relationship between the drive device 100 and the rotor 62. Components corresponding to those in the previously described embodiment are denoted by the same reference numerals, and repeated descriptions are made only when necessary. The following descriptions are the same. Figure 2 An example of an inner rotor is shown. As shown, rotor 62 is composed of two poles: a north pole and a south pole. Drive device 100, which integrates sensors 11, 12, and 13 of sensor unit 10, is installed close to rotor 62. Centerline 600 passes through the center of main sensor 11. Dashed line 603 represents a line running from center O of rotor 62 through the center of auxiliary sensor 12, and dashed line 604 represents a line running from center O through the center of auxiliary sensor 13.

[0036] The angles α1 and α2 formed between the dashed lines 603 and 604 and the centerline 600 create phase differences between the output signal of the main sensor 11 and the output signals of the auxiliary sensors 12 and 13. Preferably, the auxiliary sensors 12 and 13 are positioned symmetrically with respect to the main sensor 11, i.e., about the centerline 600. Specifically, they are arranged so that α1 and α2 are equal. By arranging the auxiliary sensors 12 and 13 symmetrically about the centerline 600, a configuration is achieved in which the phase of the output signal of one of the auxiliary sensors 12 and 13 is advanced relative to the output signal of the main sensor 11, while the phase of the output signal of the other lags by the same phase difference.

[0037] During forward rotation of rotor 62, indicated by arrow 601, auxiliary sensor 12 outputs an output signal that precedes main sensor 11, while auxiliary sensor 13 outputs an output signal that follows. During reverse rotation, indicated by arrow 602, auxiliary sensor 13 outputs an output signal that precedes main sensor 11, while auxiliary sensor 12 outputs an output signal that follows main sensor 11. Drive device 100 in this embodiment detects the rotational position of rotor 62 using the phase difference between the output signals of main sensor 11 and auxiliary sensors 12 and 13. Furthermore, the phasing relationship between the output signals of main sensor 11 and auxiliary sensors 12 and 13 varies depending on the rotational direction of rotor 62. This allows detection of the rotational direction of rotor 62, thus avoiding the risk of improper startup of motor 60. Furthermore, the rotation of rotor 62 is sometimes represented as the rotation of motor 60.

[0038] The output signals of the sensors 11, 12, and 13 are generated in response to the proximity of the north and south poles of the permanent magnets of the rotor 62. That is, the magnitude of the output signals of the sensors 11, 12, and 13 is independent of the rotational speed of the rotor 62. Therefore, by setting the levels of the output signals of the auxiliary sensors 12 and 13, obtained through calibration at startup, as the threshold voltages of the comparators 23 and 24, and comparing these threshold voltages with the output signals from the auxiliary sensors 12 and 13 in the comparators 23 and 24, the rotational position of the rotor 62 can be detected.

[0039] In the case of an outer rotor, the drive device 100 is disposed inside the rotor 62 , that is, on the side of the center O. Similarly to the inner rotor, the sensors 11 , 12 , and 13 can be configured to respond to the rotation of the rotor 62 .

[0040] Next, use Figure 3 A method of driving the driving device 100 will be described. Figure 3This diagram illustrates the driving method of a brushless motor drive device and the relationship between the output signals of sensors 11, 12, and 13 when rotor 62 rotates forward. The solid line 501 in the upper section represents the rotation angle of rotor 62. When rotor 62 is composed of a two-pole permanent magnet, the rotation angle of rotor 62 corresponds to the electrical angle. The timing of a rotation angle of 180 degrees is indicated by P18, and the timing of a rotation angle of 360 degrees and a rotation angle of 0 degrees is indicated by P00.

[0041] The next section shows the output signal 502 of the main sensor 11 supplied via the offset canceller 21 as a pseudo-sine wave. For example, the main sensor 11 generates a negative voltage when the north pole of the rotor 62 approaches, and a positive voltage when the south pole approaches. When the south pole and north pole of the rotor 62 connect, the output signal 502 of the main sensor 11 reaches zero. Specifically, at times P0 and P10, corresponding to the time when the south pole and north pole of the rotor 62 connect, the output signal 502 of the main sensor 11 reaches zero. These times P0 and P10 are zero-crossing points.

[0042] In the next section, the output signals 503 and 504 of the auxiliary sensors 12 and 13 are represented by pseudo-sine waves. For convenience, the subscripts (12) and (13) representing the corresponding auxiliary sensors 12 and 13 are added to the output signals 503 and 504. Similar to the main sensor 11, the auxiliary sensors 12 and 13 generate a negative voltage when the north pole of the rotor 62 approaches, and generate a positive voltage when the south pole approaches. The output signal 503 of the auxiliary sensor 12 is compared with the threshold voltage thA1 and the threshold voltage thA2 in the comparator 23. Based on the comparison results with the threshold voltages thA1 and thA2, the timing P1 that is 120 degrees ahead of the timing P18 at which the output signal 502 of the main sensor 11 reaches zero and the timing P2 that is 60 degrees behind are detected.

[0043] Similarly, the comparator 24 compares the output signal 504 of the auxiliary sensor 13 with the threshold voltages thB1 and thB2, detecting timing P3, which is 60 degrees ahead of, and timing P4, which is 120 degrees behind, the timing P18 at which the output signal 502 of the main sensor 11 reaches zero. The threshold voltages thA1, thA2, thB1, and thB2 are set based on, for example, the output levels of the output signals of the auxiliary sensors 12 and 13 during calibration performed at the start of the motor 60. Calibration will be described later.

[0044] The next section shows digital signal 505 generated based on output signal 502 from main sensor 11. Output signal 502 from main sensor 11, supplied via offset canceller 21, is shaped by comparator 22 to generate digital signal 505. At timing P0, when output signal 502 changes from a negative voltage to a positive voltage, i.e., at a zero-crossing point, digital signal 505 changes from an L level to an H level. Comparator 22, for example, has a hysteresis characteristic and switches between an H level and an L level at the zero-crossing point of output signal 502.

[0045] The next section shows a digital signal 506 of the auxiliary sensor 12 outputted from the comparator 23. The comparator 23 outputs a digital signal 505 of H level and L level in response to, for example, a low-side threshold voltage thA1 and a high-side threshold voltage thA2.

[0046] The next section shows a digital signal 507 of the auxiliary sensor 13 outputted from the comparator 24. The comparator 24 outputs digital signals of H level and L level in response to, for example, a low-side threshold voltage thB1 and a high-side threshold voltage thB2.

[0047] The threshold voltages thA1, thA2, thB1, and thB2 of each auxiliary sensor 12 and 13 are set during calibration at motor startup. These threshold voltages thA1, thA2, thB1, and thB2 are set based on the output levels of the auxiliary sensors 12 and 13 at the timing when the electrical angle phase difference between the output signals 502 of the main sensor 11 reaches 120 degrees.

[0048] The drive signal generator 35 uses the three digital signals 505 to 507 to generate drive signals HU, LU, HV, LV, HW, and LW to be supplied to the output transistors 41 to 46. The drive signal HU indicated by a solid line 610 is supplied to the upper output transistor 41 of the U phase, and the drive signal LU indicated by a solid line 611 is supplied to the lower output transistor 44 of the U phase.

[0049] Similarly, in the next section, the drive signal HV represented by the solid line 612 is supplied to the output transistor 42 of the upper stage of the V phase, and the drive signal LV represented by the solid line 613 is supplied to the output transistor 45 of the lower stage of the V phase. Similarly, in the next section, the drive signal HW represented by the solid line 614 is supplied to the output transistor 43 of the upper stage of the W phase, and the drive signal LW represented by the solid line 615 is supplied to the output transistor 46 of the lower stage of the W phase.

[0050] Each output transistor 41 to 46 is driven by drive signals HU, LU, HV, LV, HW, and LW, for example, with 120-degree conduction. For ease of explanation, drive signals HU, HV, and HW represent signals for turning on P-type output transistors 41 to 43, and thus are represented with the H / L logic levels inverted.

[0051] According to the drive device 100 of this embodiment, drive signals HU, LU, HV, LV, HW, and LW are generated based on the output levels of the output signals of the integrally integrated main sensor 11 and two auxiliary sensors 12 and 13. During calibration performed when the motor 60 is started, the threshold voltages thA1, thA2, thB1, and thB2 of the comparators 23 and 24 are set based on the output levels of the output signals of the auxiliary sensors 12 and 13 detected at a predetermined phase difference relative to the output signal of the main sensor 11. By comparing these threshold voltages with the output signals from the auxiliary sensors 12 and 13, the rotational position of the rotor 62 can be detected. Even with the integrated main sensor 11 and the auxiliary sensors 12 and 13, the rotational position of the rotor 62 can be detected in the same manner as with conventional three-phase brushless motors. Furthermore, since appropriate threshold voltages can be set for each motor during calibration, a versatile drive device 100 can be provided.

[0052] Next, use Figure 4 One embodiment of a method for generating a drive signal by the drive device 100 when the rotor 62 rotates forward will be described. Figure 4 This is a diagram for explaining the output signals of the sensors 11, 12, and 13 when the rotor 62 rotates forward. Figure 3 In this embodiment, the digital signal 505 of the main sensor 11 and the digital signal 1 of the auxiliary sensor 12 are used to generate the digital signal 2 .

[0053] For example, time T2 is measured, corresponding to the 60-degree phase difference between the timing P18 at which the digital signal 505 of the main sensor 11 rises and the timing P2 at which the digital signal 1 of the auxiliary sensor 12 falls. This measurement is performed, for example, by a counter (not shown) provided in the signal processing unit 31. Using the measured time T2, the signal processing unit 31 performs arithmetic processing to calculate time T3 corresponding to the 60-degree phase difference, as well as time T1, T4, and T6. Using the measured time T2 and the calculated times T1, T3, and T6, a digital signal 2 is generated. This digital signal 2 is generated based on the output signal 502 of the main sensor 11 and has a phase that lags by 120 degrees relative to the digital signal 505. The total value of time T1 to T6 constitutes one cycle of digital signal 2. Digital signal 2 is generated by the drive signal generating unit 35.

[0054] It is also possible to perform calculations using only the digital signal 505 from the main sensor 11 and generate a digital signal 2 with a phase delay of 120 degrees. However, by also using information from the auxiliary sensor 12, a more accurate digital signal 2 can be generated. Furthermore, it is also possible to use information on frequency fluctuations over multiple cycles to predict time T3.

[0055] In the signal generation method of this embodiment, the digital signal 505 of the main sensor 11 and the digital signal 1 of the auxiliary sensor 12 are used for calculation processing to generate a digital signal 2 that changes between the H level and the L level at the timing of a predetermined phase difference. Specifically, the digital signal 2 represented by the solid line 508 is generated, and its phase lags by 120 degrees relative to the output signal 502 of the main sensor 11. The method of generating a drive signal using the digital signals 1 and 2 of the main sensor 11 and the auxiliary sensor 12 is similar to the method of generating a drive signal using the digital signals 1 and 2 of the main sensor 11 and the auxiliary sensor 12. Figure 3 The drive signals HU, LU, HV, LV, HW, and LW are generated by the drive signal generating unit 35.

[0056] The signal generation method in which the digital signal 1 and the digital signal 2 are generated differently depending on the phase difference between the output signal 502 of the main sensor 11 and the output signal 503 of the auxiliary sensor 12 will be described later.

[0057] Figure 5 This diagram explains how the output signals of the sensors 11, 12, and 13 and the drive signal are generated when the rotor 62 rotates in reverse. In the upper section, a solid line 511 indicates the rotation angle of the rotor 62. In the lower section, an output signal 512 of the main sensor 11 is shown.

[0058] In the next section, the output signals of the auxiliary sensors 12 and 13 are represented by solid lines 513 and 514. The relationship between the magnetic poles of the permanent magnets of the rotor 62 and the output voltages of the sensors 11, 12, and 13 is the same as when the rotor 62 rotates forward.

[0059] In the next section, solid line 515 represents the digital signal of main sensor 11 output by comparator 22. It changes to an H level and an L level at the timings P0 and P10 of the zero crossings of main sensor 11. In the next section, solid line 516 represents digital signal 1, which is 120 degrees ahead in phase with digital signal 515 of main sensor 11. Digital signal 516 is generated based on output signal 514 of auxiliary sensor 13.

[0060] Specifically, during calibration at motor startup, the level of the output signal from auxiliary sensor 13 at timing P3, which is 120 degrees ahead of the output signal from main sensor 11, is detected and set as threshold voltage thB2. Furthermore, the level of the output signal from main sensor 11 at timing P4, which is 60 degrees behind the output signal 512 from main sensor 11, is detected and set as threshold voltage thB1. Comparator 24, with threshold voltages thB1 and thB2 set, generates digital signal 1, represented by solid line 516.

[0061] In the signal generation method of this embodiment, digital signal 2, represented by a solid line 518, is generated using digital signal 515 from main sensor 11 and digital signal 1 from auxiliary sensor 13. For example, time T12 is measured, corresponding to the 60-degree phase difference between timing P18, when digital signal 515 from main sensor 11 falls, and timing P4, when digital signal 1 from auxiliary sensor 13 rises. This measurement is performed, for example, by a counter (not shown) provided in signal processing unit 31. Using the measured time T12, signal processing unit 31 performs arithmetic processing to calculate time T13, as well as time T11, T14, and T16 corresponding to the 60-degree phase difference. Using the measured time T12 and the calculated times T11, T13, and T16, digital signal 2 is generated based on output signal 512 from main sensor 11, with a phase that lags by 120 degrees relative to digital signal 515. The total value of time T11 to T16 constitutes one cycle of digital signal 2. The digital signal 2 is generated by the drive signal generating unit 35 .

[0062] It is also possible to perform calculation processing using only the digital signal 515 of the main sensor 11 and generate the digital signal 2 with a phase delay of 120 degrees. However, by also using information from the auxiliary sensor 13, a more accurate digital signal 2 can be generated.

[0063] In the signal generation method of this embodiment, the auxiliary sensor for generating the digital signal 1 is selected according to the rotation direction of the rotor 62, and the timing of the H / L switching of the digital signal 1 is the timing before the output signal of the auxiliary sensor reaches the peak and valley values. Therefore, the circuit structure for generating the digital signal 1 based on the output signal of the auxiliary sensor can be simplified.

[0064] For example, the comparator 24 that outputs the digital signal 516 from the auxiliary sensor 13 can be formed by a window comparator that compares the two threshold voltages thB1 and thB2 with the output signal 514 of the auxiliary sensor 13. The method of generating the drive signals HU, LU, HV, LV, HW, and LW using the digital signals 516 and 518 of the main sensor 11 and the auxiliary sensor 13 is similar to the method of generating the drive signals HU, LU, HV, LV, HW, and LW using the digital signals 516 and 518 of the main sensor 11 and the auxiliary sensor 13. Figure 3The implementation of the embodiment is the same and is therefore omitted.

[0065] use Figure 6 as well as Figure 7 A signal generation method will be described in the case where the phase difference between the output signals of the main sensor 11 and the auxiliary sensor 12 is equal to or smaller than a threshold value when the rotor 62 is rotating forward. Figure 7 It will Figure 6 The upper to 3rd level are enlarged views.

[0066] In the calibration at the start of the motor 60, the phase difference between the output signal 502 of the main sensor 11 and the output signal 503 of the auxiliary sensor 12 when the rotor 62 rotates forward is compared with a predetermined threshold value. Figure 6 and Figure 7 The phase difference θ1 between the output signal 502 of the main sensor 11 shown in the second stage and the output signal 503 of the auxiliary sensor 12 shown in the third stage is compared with a threshold value. The threshold value is, for example, 30 degrees.

[0067] As in Figure 7 As shown in the enlarged figure, the phase difference θ1 between the output signals of the main sensor 11 and the auxiliary sensor 12 is detected by the phase difference between the timing PU when the output signal 502 of the main sensor 11 reaches a peak value and the timing PU12 when the output signal 503 of the auxiliary sensor 12 reaches a peak value, or the phase difference between the timing PB when the output signal 502 of the main sensor 11 reaches a valley value and the timing PB12 when the output signal 503 of the auxiliary sensor 12 reaches a valley value.

[0068] The timing PB at which the output signal 502 of the main sensor 11 reaches a bottom value occurs 90 degrees prior to the timing P18 at which the main sensor 11 has rotated 180 degrees. Therefore, when the phase difference θ1 is 30 degrees or less, the timing P1 of the output signal 503 of the auxiliary sensor 12, which precedes the timing P0 at which the output signal 502 of the main sensor 11 reaches zero by 120 degrees, occurs at a predetermined position before the timing PB12 at which the output signal 503 of the auxiliary sensor 12 reaches a bottom value. Similarly, the timing P2 at which the phase of the output signal 503 of the auxiliary sensor 12 lags 60 degrees relative to the timing P0 at which the output signal 502 of the main sensor 11 reaches zero, occurs at a predetermined position prior to the timing PU12 at which the output signal 503 of the auxiliary sensor 12 reaches a peak value.

[0069] Therefore, by comparing the output signal 503 of the auxiliary sensor 12 with the threshold voltages thA1 and thA2 set during calibration, it is possible to detect the rotational position of the rotor 62 at timing P1, which is 120 degrees ahead of the timing P18 at a rotation angle of 180 degrees, and at timing P2, which is 60 degrees behind the timing P18 at which the main sensor 11 rotates. For example, the comparator 23 can be configured as a window comparator that compares the two threshold voltages thA1 and thA2 with the output signal 503 of the auxiliary sensor 12.

[0070] and Figure 4 The same situation, in Figure 6 The digital signal 2 represented by the solid line 508 in the lower section can generate T1 to T6 using the digital signal 505 of the main sensor 11 and the digital signal 1 of the auxiliary sensor 12, and generates a signal with a phase lag of 120 degrees. The method of generating the drive signals HU, LU, HV, LV, HW, and LW using the digital signal 1 generated based on the output signal 502 of the main sensor 11 and the auxiliary sensor 12 and the digital signal 2 is similar to the method of generating the drive signals HU, LU, HV, LV, HW, and LW using the digital signal 1 generated based on the output signal 502 of the auxiliary sensor 12. Figure 3 The examples are the same and therefore omitted.

[0071] use Figure 8 as well as Figure 9 A signal generation method will be described in the case where the phase difference between the output signal of the main sensor 11 and the output signal of the auxiliary sensor 12 is larger than a threshold value when the rotor 62 rotates forward. Figure 9 It will Figure 8 The upper to 3rd level are enlarged views.

[0072] The timing PB at which the output signal 502 of the main sensor 11 reaches a bottom value is 90 degrees prior to the timing P18 at which the main sensor 11 has rotated 180 degrees, and the timing PU at which the output signal 502 reaches a peak is 90 degrees later. Therefore, if the phase difference θ2 between the timing PU at which the output signal 502 of the main sensor 11 reaches a peak and the timing PU14 at which the output signal 523 of the auxiliary sensor 12 reaches a peak, or between the timing PB at which the output signal 502 of the main sensor 11 reaches a bottom value and the timing PB14 at which the output signal 523 of the auxiliary sensor 12 reaches a bottom value, is greater than 30 degrees, the timing P14 of the output signal 524 of the auxiliary sensor 13, which precedes the timing P0 at which the output signal 502 of the main sensor 11 reaches zero by 60 degrees, is located at a predetermined position before the timing PB13 at which the output signal 524 of the auxiliary sensor 13 reaches a bottom value. Similarly, the timing P13 at which the phase of the output signal 524 of the auxiliary sensor 13 lags by 120 degrees from the timing P0 at which the output signal 502 of the main sensor 11 becomes zero exists at a predetermined position before the timing PU13 at which the output signal 524 of the auxiliary sensor 13 reaches a peak.

[0073] Therefore, when the phase difference is greater than 30 degrees, auxiliary sensor 13 is selected and the threshold voltages thB1 and thB2 set during calibration are compared with the output signal 524 of auxiliary sensor 13. This allows detection of the rotational position of rotor 62 at timing P14, which precedes by 60 degrees and timing P13, which lags by 120 degrees relative to timing P18, which is a rotation angle of 180 degrees from main sensor 11. Since there is no need to include a circuit to detect the valleys and peaks of output signal 524 from auxiliary sensor 13, the circuit configuration can be simplified. For example, comparator 24, which generates digital signal 526 from auxiliary sensor 13, can be implemented as a window comparator that compares the two threshold voltages thB1 and thB2 with the output signal 524 of auxiliary sensor 13.

[0074] When the phase difference θ2 between the output signals of the main sensor 11 and the auxiliary sensor 12 is greater than the threshold value of 30 degrees, the output signal 524 of the auxiliary sensor 13 is used to generate the digital signal 1. The digital signal 2 represented by the solid line 528 can be processed by the operation of the digital signal 1 to generate a signal that is 120 degrees behind the phase of the digital signal 1. Figure 4 In the same manner, the information of the digital signal 525 of the main sensor 11 can also be used to measure the time corresponding to the phase difference of 60 degrees between the digital signal 1 of the auxiliary sensor 13, and the measured value can be used for calculation processing to generate the digital signal 2.

[0075] In addition, as described above, by arranging the auxiliary sensors 12 and 13 at positions that are linearly symmetrical relative to the main sensor 11, a phase difference that is the same as the phase difference θ2 between the output signals of the main sensor 11 and the auxiliary sensor 12 is generated between the output signal 502 of the main sensor 11 and the output signal 524 of the auxiliary sensor 13.

[0076] Figure 10This diagram illustrates signal generation when the output signals of the auxiliary sensors 12 and 13 are offset. This example illustrates the case where the output signal 533 of the auxiliary sensor 12 is offset during forward rotation of the rotor 62. As described above, threshold voltages thA1 and thA2 are set based on the values ​​of the output signal 533 of the auxiliary sensor 12 at predetermined timings P1 and P2, obtained during calibration at motor startup. The value of the output signal 533 of the auxiliary sensor 12 at timing P1, which precedes the rotor 62's 180-degree rotation angle by 120 degrees, is set as threshold voltage thA1, while the value of the output signal 533 at timing P2, which lags the rotor 62's rotation angle by 60 degrees, is set as threshold voltage thA2. Digital signal 1, represented by a solid line 536, is generated based on the comparison of the threshold voltages thA1 and thA2 with the output signal 533 of the auxiliary sensor 12. Digital signal 2, represented by a solid line 538, is generated using digital signal 535 generated based on the output signal 502 of the main sensor 11.

[0077] In this embodiment, the threshold voltages thA1 and thA2 are set according to the offset of the auxiliary sensor 12. The threshold voltages thB1 and thB2 of the comparator 24, to which the output signal 534 of the auxiliary sensor 13 is supplied, are also set according to the output signal 534 corresponding to the offset of the auxiliary sensor 13. Since the threshold voltages thA1, thA2, thB1, and thB2 of the comparators 23 and 24 can be set according to the offset, there is no need to provide an offset cancellation unit for the auxiliary sensors 12 and 13. Therefore, the circuit configuration can be simplified. Figure 4 In the same manner, the information of the digital signal 535 of the main sensor 11 can also be used to measure the time corresponding to the phase difference of 60 degrees between the digital signal 1 of the auxiliary sensor 12, and the measured value can be used for calculation processing to generate the digital signal 2.

[0078] Figure 11 1 is a diagram showing a flow chart of one embodiment of calibration. The motor 60 is forced to rotate forward at a certain frequency (S10). A drive signal of a predetermined pattern for forcibly rotating the motor 60 forward at a certain frequency (rotational speed) is generated by the drive signal generator 35 and supplied to each output transistor 41 to 46 of the output circuit unit 40. The raw data of the predetermined pattern is stored in the storage unit 50, for example, and is supplied to the drive signal generator 35 at a predetermined timing via the signal processing unit 31. The raw data may also be supplied from outside the drive device 100.

[0079] The phase difference between the output signal of the main sensor 11 and the output signal of the auxiliary sensor 12 is detected (S11). For example, the phase difference between the peak values ​​of the output signals of the main sensor 11 and the auxiliary sensor 12 is detected. By detecting the phase difference between the peak values, for example, the influence of a bias in the output signal of the auxiliary sensor 12 can be eliminated.

[0080] A comparison is made to determine whether the phase difference is less than or equal to a threshold of 30 degrees (S12). If the phase difference is less than or equal to 30 degrees (S12: Yes), the auxiliary sensor 12 is selected (S13). Specifically, the auxiliary sensor 12, which precedes the main sensor 11 during forward rotation of the rotor 62, is selected, and the output level of the auxiliary sensor 12 output signal is detected at a phase that is 120 degrees ahead of the main sensor 11 output signal (S15).

[0081] If the phase difference is greater than 30 degrees (S12: No), the auxiliary sensor 13 is selected (S14). That is, the auxiliary sensor 13 is selected to follow the main sensor 11 during the forward rotation of the rotor 62, and the output level of the output signal of the auxiliary sensor 13 is detected at a phase that lags 120 degrees relative to the output signal of the main sensor 11 (S16).

[0082] The selection result and output level of the auxiliary sensor when the motor 60 rotates forward are stored in the memory of the storage unit 50 (S17). The stored detection level is set as the threshold voltage of the comparator.

[0083] Next, the motor 60 is forcibly reversed at a constant frequency (S18). The drive signal generator 35 generates a drive signal of a predetermined pattern that forcibly reverses the motor 60 at a constant frequency (rotational speed) and supplies it to the output transistors 41 to 46 of the output circuit 40. The raw data underlying the predetermined pattern is stored in the storage unit 50 and supplied to the drive signal generator 35 at a predetermined timing via the signal processing unit 31. The forced reverse rotation step is provided to prepare for the situation in which the motor 60 is reversed.

[0084] When the auxiliary sensor 12 is selected during the forward rotation of the motor 60 (S19: Yes), that is, when the phase difference between the output signals of the main sensor 11 and the auxiliary sensor 12 is 30 degrees or less, the auxiliary sensor 13 is selected (S20), and the output level of the output signal of the auxiliary sensor 13 at a phase 120 degrees ahead of the output of the main sensor 11 is detected (S22). Figure 5 As described in , the detection level (thB2) at timing P3 before the output level of the output signal of the auxiliary sensor 13 reaches a peak, and the output level (thB1) of the output signal at timing P4 before reaching a valley can be detected as setting values ​​for the threshold voltage of the comparator 24.

[0085] If the auxiliary sensor 12 is not selected during forward rotation of the motor 60 ( S19 : NO), the auxiliary sensor 12 is selected ( S21 ), and the output level of the auxiliary sensor 12 output signal, which is at a phase that lags 120 degrees relative to the output of the main sensor 11, is detected ( S23 ). This allows the output level of the auxiliary sensor 12 output signal to be detected before reaching a bottom value and before reaching a peak value, and these values ​​are used as setting values ​​for the threshold voltages thA1 and thA2 of the comparator 23.

[0086] The selection result and output level of the auxiliary sensor when the motor 60 is reversed are stored in the memory of the storage unit 50 (S24). The stored output levels are set as the threshold voltages thA1, thA2, thB1, and thB2 of the comparators 23 and 24.

[0087] For example, the threshold voltages of the comparators 23 and 24 are set by automatically performing calibration at motor startup. By comparing each threshold voltage with the output signals of the auxiliary sensors 12 and 13, the timing at which each threshold voltage is reached is detected, thereby enabling detection of the rotational position of the rotor 62. Alternatively, the drive signal for calibration during startup may be supplied to the output circuit unit 40 from outside the drive device 100.

[0088] Figure 12 This figure shows an example of a planar layout of an integrated drive device 100. Drive device 100 integrates a main sensor 11, auxiliary sensors 12 and 13, a detection unit 20, a control unit 30, an output circuit unit 40, and a storage unit 50. Auxiliary sensors 12 and 13 are formed on either side of the main sensor 11. Providing auxiliary sensors 12 and 13 on either side of the main sensor 11 allows for a configuration in which the rotational position of the rotor 62 is detected, either ahead of or following the rotation of the main sensor 11.

[0089] When the main sensor 11 and the auxiliary sensors 12 and 13 are formed of silicon, they can be integrated with the detection unit 20, the control unit 30, the output circuit unit 40, and the storage unit 50 on a single silicon substrate, for example, and can be integrated into one body by molding resin.

[0090] When the Hall elements constituting each sensor 11, 12, and 13 are made of compound semiconductors, a single chip (not shown) containing the Hall elements formed of compound semiconductors can be integrated with a silicon substrate containing other circuit components through a multi-chip configuration, for example, by molding the components together using a molded resin. Furthermore, some components can be externally located and constructed using separate integrated circuits. For example, the output transistors 41 to 46 constituting the output circuit 40 are constructed using high-voltage DMOS (Double Diffused MOS) transistors, which generate heat, and therefore can be constructed as an external integrated circuit device.

[0091] Figure 13 This is an exploded perspective view of an embodiment of a motor having a built-in drive device 100. The drive device 100 is placed on a support base 200. An excitation coil (not shown) is provided on a stator 202, and an excitation current is supplied via output wires 301 to 303.

[0092] The upper case 201 and the lower case 203 accommodate the rotor 62 composed of permanent magnets, the stator 202 , and the support base 200 .

[0093] Since the main sensor 11 and the auxiliary sensors 12 and 13 are integrated into the drive device 100, the right side 200A of the support base 200 indicated by the dotted line can be eliminated. This can reduce the cost of the motor. For example, the annular flat plate (not shown) can be divided into two halves, with one side used as the support base 200 and the other side used as the support base for another motor. By making the drive device 100 integrate the main sensor 11 and the auxiliary sensors 12 and 13 into one, the cost of the motor can be reduced.

[0094] In the above embodiment, the case where the rotor 62 has two poles has been described. However, even when the rotor 62 has four poles or eight poles, the rotational position of the rotor 62 can be detected using the drive device 100 in the same manner.

[0095] While several embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments may be implemented in various other ways, and various omissions, substitutions, and modifications may be made without departing from the gist of the invention. These embodiments and their variations are intended to be included within the scope and gist of the invention, and are intended to be included in the invention set forth in the claims and their equivalents.

Claims

1. A brushless motor drive device comprising: an output portion for supplying an excitation current to an excitation coil for generating a magnetic field for rotating the rotor; a position detection unit for detecting a rotational position of the rotor; and a drive control unit that generates a drive signal based on the detection signal from the position detection unit and supplies the drive signal to the output unit; The position detection unit includes: a first detection element for detecting a rotational position of the rotor; a second detection element that detects the rotational position of the rotor before the first detection element; and The third detection element follows the first detection element to detect the rotation position of the rotor. The first to third detection elements are integrated into one. The above-mentioned drive control unit is, When the rotor rotates forward, when the phase difference between the detection signal of the first detection element and the detection signal of the second detection element is below a specified threshold value, the detection signal of the first detection element and the detection signal of the second detection element are used to generate the drive signal. When the phase difference between the detection signal of the first detection element and the detection signal of the second detection element is greater than the specified threshold value, the detection signal of the first detection element and the detection signal of the third detection element are used to generate the drive signal.

2. The brushless motor drive device according to claim 1, wherein: The first to third detection elements are integrated with the drive control unit.

3. The brushless motor driving device according to claim 1, wherein: The above-mentioned threshold is 30 degrees.

4. The brushless motor drive device according to any one of claims 1 to 3, wherein: A threshold voltage generating unit is provided, the threshold voltage generating unit setting the detection levels of the detection signal of the second detection element and the detection signal of the third detection element.

5. The brushless motor drive device according to any one of claims 1 to 3, wherein: A storage unit is provided for storing values ​​of detection signals of the second detection element and the third detection element obtained during calibration in which the rotor is rotated under predetermined conditions.

6. The brushless motor drive device according to any one of claims 1 to 3, wherein: An offset canceller is provided only on the first detection element. The first to third detection elements are integrated into one body by molded resin.

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