JP2015211593A - Rotational position detection device, and brushless dc motor sinusoidal wave drive controller employing the rotational position detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve detection accuracy of a rotor position in simple and cost-reduced configuration.SOLUTION: A rotational position detection device includes: a magnetic detection section for detecting a magnetic change in the vicinity of a rotor rotating a magnetic pole; a rectangular wave generation circuit for converting an output signal of the magnetic detection section into a rectangular wave signal; a triangular wave generation circuit for converting an output signal of the rectangular wave generation circuit into a triangular wave; an A/D conversion circuit for converting an output signal of the triangular wave generation circuit into a digital signal; processing means which inputs the output signal of the rectangular wave generation circuit and an output signal of the A/D conversion circuit; and storage means for previously storing correspondence information between a rotor position number indicating a rotational position of the rotor and a magnetic detection value number that is a numerical value corresponding to a detection value by the magnetic detection section. The processing means calculates a magnetic detection value number (d) corresponding to an output value of the A/D conversion circuit in accordance with a state of the rectangular wave signal from the rectangular wave generation circuit on the basis of the correspondence information, further, calculates a rotor position number corresponding to the magnetic detection value number (d) and outputs the rotor position number as an absolute rotational position value.

Description

  The present invention relates to a rotational position detection device suitable for high-performance driving and position control of a brushless DC motor, and a brushless DC motor sine wave drive control device using the rotational position detection device.

  Conventionally, in this kind of invention, there is an encoderless brushless DC motor described in Patent Document 1, for example. This motor uses a magnetic pole position signal at an angle of 60 ° obtained from the built-in Hall element to detect edges that are polarity change points, and calculates based on the relationship between time, speed, etc. counted between the edges. Thus, the rotor position (electrical angle) is estimated.

However, according to the above prior art, since the rotor position between the magnetic pole position signals at every angle of 60 ° is estimated from the calculation, there is a possibility that a sufficient result cannot be obtained accurately.
In particular, when the rotation angle of the rotor is controlled, or when the brushless DC motor is driven in a sine wave by the 180 ° driving method, detection of the rotor position with higher accuracy is required. Thus, although it is conceivable to detect the rotation angle with high accuracy using a rotary encoder, problems such as cost and installation space are likely to occur.

Japanese Patent Laid-Open No. 10201284

  The present invention has been made in view of the above-described conventional circumstances, and a problem to be solved by the present invention is a rotational position detection device capable of improving the detection accuracy of the rotor position with a simple and low-cost configuration, and the rotational position detection. An object of the present invention is to provide a brushless DC motor sine wave drive control device using the device.

A rotational position detection device as one means for solving the above problems includes a magnetic detection unit that detects a magnetic change in the vicinity of a rotor that rotates a magnetic pole, and a square that converts an output signal of the magnetic detection unit into a square wave signal. Wave generation circuit, triangular wave generation circuit that converts a square wave signal of the square wave generation circuit into a triangular wave signal, an A / D conversion circuit that converts the triangular wave signal of the triangular wave generation circuit into a digital signal, and the square wave generation circuit A square wave signal and a digital signal of the A / D converter circuit, a rotor position number indicating the rotational position of the rotor, and a magnetic detection value number which is a numerical value corresponding to the detection value by the magnetic detection unit And a storage means for preliminarily storing correspondence information with the processing means, wherein the processing means responds to the state of the square wave signal of the square wave generation circuit from the correspondence information. The seek the magnetic detection value number corresponding to the digital value of the A / D converter, it obtains the further rotor position number corresponding to the magnetic detection value number, and outputs the rotor position number as an absolute rotational position value each.
Here, in the “correspondence information”, the correspondence between the rotor position number indicating the rotational position of the rotor and the magnetic detection value number that is a numerical value corresponding to the detection value by the magnetic detection unit is stored as a data table. And a mode in which the correspondence is stored as a mathematical expression.

  As a more preferable means, the correspondence relationship information includes a plurality of rotor position numbers in which values indicating the rotational positions of the rotor are arranged in order, and corresponding to the plurality of rotor position numbers and values detected by the magnetic detection unit. A data table having a plurality of magnetic detection value numbers which are corresponding numerical values.

  As a more preferable means, the processing means selects the magnetic detection value number corresponding to the output value of the triangular wave generation circuit from the data table according to whether the square wave signal is an H signal or an L signal. The rotor position number corresponding to the selected magnetic detection value number is set as the absolute rotation position value.

More preferably, the data table includes a plurality of the rotor position numbers and the magnetic detection value numbers in a data group for each pole pair number corresponding to the pole pair of the rotor. The origin position of the pole pair is acquired by the origin sensor, the period of the square wave signal is counted from this acquisition time point, the position range of the pole pair is recognized according to the count value, and the pole pair corresponding to the pole pair position range is detected. The data group of the pair number is selected from the data table.
Here, the “origin sensor” may be configured to detect a specific position in the circumferential direction of the rotor and output the detection signal as an origin signal. The sensor is provided by a sensor provided separately from the magnetic detection unit. The specific position may be detected, or the specific position may be detected by using a detection signal of the magnetic detection unit.

  The brushless DC motor sine wave drive control device using the rotational position detection device includes a brushless DC motor in which the magnetic detection unit is provided in the vicinity of a rotor, and an inverter circuit that supplies power to the brushless DC motor. And the processing means corrects a drive command to the inverter circuit in accordance with the absolute rotational position value.

  Since the present invention is configured as described above, the detection accuracy of the rotor position can be improved with a simple and low-cost configuration.

The block diagram of the brushless DC motor sine wave drive control apparatus using the rotational position detection apparatus which concerns on this invention is shown. It is a schematic diagram which shows an example of a brushless DC motor. It is a graph which superimposes the output waveform of a magnetic detection part, and the output waveform of a triangular wave generation circuit, and a vertical axis | shaft shows an output voltage and a horizontal axis shows an electrical angle. (A) is an output waveform of the magnetic pole detection unit, (b) is an output waveform of the square wave generation circuit, and (c) is an output waveform of the triangular wave generation circuit. It is a figure which shows the image which divided | segmented the output waveform of the triangular wave generation circuit with the pulse signal. It is a figure which shows the image put together for every pole pair number while dividing the output waveform of the triangular wave generation circuit corresponding to one magnetic pole detection part with a pulse signal. It is a flowchart which shows the procedure which detects a rotation position, and an image figure which shows an example of a data table.

  Next, a preferred example of the present embodiment will be described in detail based on the drawings.

  As shown in FIG. 1, this rotational position detection device converts the magnetic detection units Hu, Hv, Hw provided in the brushless DC motor 10 and the output signals of these magnetic detection units Hu, Hv, Hw into square wave signals. A square wave generation circuit 20 that converts the square wave signal of the square wave generation circuit 20 into a triangular wave, an A / D conversion circuit 40 that converts the triangular wave signal of the triangular wave generation circuit 30 into a digital signal, A processing means 50 for processing signals input from the square wave generation circuit 20 and the A / D conversion circuit 40 to output an absolute rotation position value, and a rotor position number indicating the rotation position of the rotor 11 of the brushless DC motor 10. And storage means 51 that stores in advance correspondence information (see FIG. 7) with the output value of the A / D conversion circuit 40. And this rotational position detection apparatus comprises the brushless DC motor sine wave drive control apparatus which drives the brushless DC motor 10 sine wave via the inverter 60 according to the example shown in FIG.

  As shown in FIG. 2, the brushless DC motor 10 includes a rotor 11 that rotatably supports a permanent magnet, a stator 12 that supports a plurality of coils around the rotor 11 at equal intervals, and a periphery of the rotor 11. 3 includes three (three in the illustrated example) magnetic detectors Hu, Hv, Hw arranged at intervals of 120 ° in the circumferential direction, and an origin sensor 13, and is a three-phase, four-pole, three-slot brushless. A DC motor is configured.

  The rotor 11 has a plurality of permanent magnets arranged at equal intervals in the circumferential direction so that the number of pole pairs is 2 (see FIG. 2), and rotates with respect to a stationary part via a rotating shaft and a bearing member (not shown). It is supported freely.

  The stator 12 has three coils of U-phase, V-phase, and W-phase arranged at equal intervals in the circumferential direction (see FIG. 2), and is supported so as not to rotate with respect to the stationary part.

The plurality of magnetic detectors Hu, Hv, Hw are respectively disposed between the coils of the stator 12 (see FIG. 2). Each of the magnetic detectors Hu, Hv, and Hw may be any sensor that detects a magnetic field and outputs a signal proportional to the magnitude of the magnetic field. For example, a Hall element is used.
Each of the magnetic detection units Hu, Hv, and Hw is disposed between adjacent coils of the stator 12 so as to be close to the outer peripheral portion of the rotor 11 that rotates the magnetic pole.
The output waveforms of these magnetic detectors Hu, Hv, Hw are three sine waves whose phases are shifted by 120 ° as shown in FIG. Each sine wave appears in a cycle of the number of pole pairs (2 cycles in the illustrated example) as the rotor 11 makes one revolution.

The origin sensor 13 may use a known rotational position sensor that detects a specific position in the circumferential direction of the rotor 11 and outputs a detection signal thereof. As an example of the origin sensor 13, a disk having one slit is fixed to a rotating shaft that rotates integrally with the rotor 11, and a photo interrupter that detects the slit is provided at a non-rotatable portion on the stator 12 side. do it. The origin sensor 13 is configured to transmit a signal that senses the slit as an origin signal in synchronization with a rising point (a position at which the L signal is switched to the H signal) in a specific square wave signal hu of the square wave generation circuit 20. Is preset.
As another example of the origin sensor 13, the origin signal is set with the origin position at a specific change point of the square wave signal of the square wave generation circuit 20 (for example, when the square wave signal hu switches from the L signal to the H signal). It is also possible to make a configuration for transmitting.

  The square wave generation circuit 20 is a well-known electronic circuit that converts each sine wave output of the magnetic detection units Hu, Hv, and Hw into an on / off digital signal using a comparator or the like. As shown in FIG. 4B, the output waveform of the square wave generation circuit 20 becomes three square waves whose phases are shifted by 120 °. Each square wave has a waveform in which the H signal and the L signal having a constant output are switched every electrical angle of 180 °. This square wave has one set of H signal and L signal as one cycle, and the rotor 11 makes one rotation, and appears as a cycle of the number of pole pairs (for example, two cycles if the number of pole pairs is 2).

The triangular wave generation circuit 30 is a known electronic circuit that converts each rectangular wave output of the square wave generation circuit 20 into a triangular wave signal using a comparator or the like.
The triangular wave generation circuit 30 may be configured to convert at least one sine wave signal among the three sine wave signals by the magnetic detection units Hu, Hv, and Hw into a triangular wave signal.
In FIG. 4C, waveforms obtained when all three sine wave signals by the magnetic detection units Hu, Hv, and Hw are converted into triangular wave signals are illustrated as hu, hv, and hw. Each triangular wave is a waveform that is switched between a linear downwardly inclined output and a linearly upwardly inclined output every 180 ° electrical angle. This triangular wave has one set of the up-tilted output and the down-tilted output as one cycle, and the rotor 11 makes one rotation and appears as a cycle of the number of pole pairs (2 cycles in the illustrated example). To do.

The A / D conversion circuit 40 is a known electronic circuit that converts the triangular wave signal of the triangular wave generation circuit 30 into a discrete digital signal.
Each time the A / D conversion circuit 40 receives a predetermined pulse signal (conversion start signal) from the processing means 50, a specific phase of the triangular wave generation circuit 30 at that time (for example, the hu phase in FIG. 4C). Is converted into a digital signal and output. The digital signal is input to the processing means 50.

The processing means 50 is a microcomputer or the like that causes the CPU to function according to a program stored in advance, and detects a square wave signal from the square wave generation circuit 20, a digital signal from the A / D conversion circuit 40, and detection by the current detection unit 70. A signal or the like is processed, and a drive command for driving the brushless DC motor 10 in a sine wave is issued to the inverter 60 according to the processing result. Further, the processing means 50 has a timer function for performing an interrupt process at a predetermined cycle, and a pulse signal (conversion start signal) generated at a predetermined cycle by the timer function is converted to an A / D conversion circuit 40. To be issued against.
The current detection unit 70 detects the drive current of the brushless DC motor 10 and inputs the detection signal to the processing means 50, and includes a known current measurement circuit.

  Further, the processing means 50 includes a storage means 51 for storing the program, a data table DT (see FIG. 7) described later, an absolute rotational position value, and the like.

  The storage means 51 is a storage device such as a nonvolatile memory. The data table DT stored in the storage means 51 is a correspondence between the rotor position number indicating the rotational position of the rotor 11 and the magnetic detection value number d, which is a numerical value corresponding to the detection value by the magnetic detection units Hu, Hv, Hw. This data indicates the relationship, and is stored in advance in the storage means 51 before the rotational position control of the brushless DC motor 10 is performed.

  According to the illustrated example, the storage means 51 is built in the processing means 50 (microcomputer). However, as another example, a storage device separate from the processing means 50 is used as the storage means 51. Is also possible.

The inverter 60 is a PWM inverter device that outputs a three-phase alternating current whose phase is shifted by 120 ° in accordance with a drive command input from the processing means 50. The inverter 60 has a phase, a frequency, and a voltage of drive power supplied to the brushless DC motor 10 in accordance with a drive command issued from the processing means 50 according to the rotational position of the rotor 11 and the current detection value of the current detection unit 70. Etc. are adjusted appropriately.
A driver circuit (not shown) made of a power device such as a transistor or FET is provided on the output side of the inverter 60 in order to control the brushless DC motor 10 with a large current.

  Next, an example of a procedure for creating the data table DT (see FIG. 7) in advance will be described in detail.

First, Tm is the total number of the pulse signals emitted from the processing means 50 to the A / D conversion circuit 40 per rotation of the rotor 11, m is the total number of the same pulse signals per electrical angle, and P is the number of pole pairs ( 5 and 6), m is obtained in advance by the following equation.
m = Tm / P ・ ・ ・ ・ ・ ・ ・ ・ Formula (1)
Then, the constant rotation speed of the rotor 11 is set to N (rpm), and the period (period of the pulse signal) Ts at which the timer interrupt is generated by the processing unit 50 is obtained by the following expression.
Ts = 1 / ((N / 60) × P × m) (2)

Then, a constant drive voltage is applied to the brushless DC motor 10 by the inverter 60 by 120 ° energization (or 180 ° energization) system drive, and the rotor 11 is rotated in an unloaded state.
Next, when the rotation of the rotor 11 becomes stable and reaches a substantially constant rotation number, the processing means 50 operates the built-in timer function, and at the cycle Ts obtained by the equation (2), the pulse signal Is transmitted to the A / D conversion circuit 40.
This pulse transmission start time is a time when the triangular wave signal of the triangular wave generating circuit 30 corresponding to the magnetic detection unit Hu becomes a predetermined voltage (for example, 5 V or 0 V). For example, the square wave signal of the square wave generating circuit 20 Judgment from the state of. According to the example shown in FIG. 4B, the time point when the square wave signal hu of the square wave generation circuit 20 switches from the L signal to the H signal is set as the pulse transmission start time.

Each time the A / D converter circuit 40 receives the pulse signal, the A / D converter circuit 40 outputs at least one phase (for example, hu phase) among the output values of the triangular wave generation circuit 30 (hu, hv, hw shown in FIG. 4A). Is converted into a digital signal and output.
Each time the processing unit 50 acquires a digital signal from the A / D conversion circuit 40, the processing unit 50 assigns a rotor position number indicating the order of the pulse signals (conversion start signal) to the digital signal.
The digital value of the one phase (hu phase) of the A / D conversion circuit 40 is handled as a magnetic detection value number d which is a numerical value corresponding to a detection value by one magnetic detection unit Hu.
The operation continues from the pulse transmission start time to the time when the rotor 11 makes one rotation (hereinafter referred to as pulse transmission end time).

The pulse transmission end time may be the time when the period of the square wave signal of the square wave generation circuit 20 is counted after the pulse transmission start time, and this count value becomes the number of pole pairs.
For example, according to an example shown in FIG. 4B, after the pulse transmission start time, the number of times the square wave signals hu, hv, hw are switched to H, L, H is counted, and this count value is a polar pair. The time when the number P, which is 2, is the pulse transmission end time.
As another example, only the period of one specific square wave signal hu may be counted.

Then, the processing means 50 includes a plurality of rotor position numbers (“1, 2, 3... M” in FIG. 7) in which values indicating the rotational position of the rotor 11 are arranged in order, and the plurality of rotor position numbers. The data groups G1, G2,... Gp are associated with a plurality of magnetic detection value numbers d (“xxx” in FIG. 7) corresponding to each of the pole pairs (in other words, in electrical angle units). In summary, the plurality of data groups G1, G2,... Gp are used as a data table DT, and the data table DT is stored in the storage means 51.
Here, the pole pair numbers are numbers respectively corresponding to a plurality of (two in the illustrated example) pole pairs of the rotor 11, and according to the data table DT of FIG. "Pair 2, ... P" indicates the pole pair number.

  The data table DT may be created by automatically causing the processing means 50 to function by a data table creation program created and stored in advance, but can also be created by manual operation on the processing means 50.

  Next, the procedure for controlling the rotational position of the brushless DC motor 10 by the processing means 50 storing the data table DT will be described in detail with reference to the flowchart of FIG.

  The processing means 50 starts the rotation of the brushless DC motor 10, acquires the origin signal from the origin sensor 13, and counts the period of the square wave signal of the square wave generation circuit 20 from this acquisition time (step 1).

  Thereafter, when the rotor 11 is at an arbitrary rotational position, the processing means 50 issues a pulse signal (conversion start signal) and acquires a digital value from the A / D conversion circuit 40 (step 2). This digital value is a value corresponding to the output signal of one specific electric detection unit (for example, Hu) among the three magnetic detection units Hu, Hv, and Hw.

Next, the processing means 50 recognizes the position range of the pole pair from the count value of the period of the square wave signal of the square wave generation circuit 20, and determines the pole pair number corresponding to this pole pair position range from the data table DT. Select (step 3).
Here, the “pole pair position range” means, in detail, the rotational position range of one pole (N pole or S pole) in a specific pole pair, in pole pair units (in other words, electrical angle units). ). For example, when the number of pole pairs of the rotor 11 is 2, as shown in FIG. 4B, if the N poles in a specific pole pair are in the mechanical angle range of 0 to 180 °, the pole pair position range is set to the pole range. If the N pole in the same pole pair is in the mechanical angle range of 180 to 360 °, the pole pair position range is the pole pair 2.

The step 3 will be described in more detail. The processing unit 50 recognizes the pole pair position range of the rotor 11 from the number of times of counting the period of the square wave signal.
For example, when the number of pole pairs is 2, if the number of times the square wave signals hu, hv, hw are in the H, L, H state is “a multiple of the pole pairs” such as 0, 2, 4, etc., the poles When the pair position range is recognized as “pole pair 1” (range of mechanical angle 0 to 180 °) and the number of times is “multiple of pole pairs + 1” such as 1, 3, 5, etc., the pole pair position range Is recognized as “pole pair 2” (range of mechanical angle 180-360 °).
As another example, only the period of one specific square wave signal hu may be counted.

Next, the processing means 50 determines whether the current time point is an output portion having a downward slope or an upward slope in a triangular wave (step 4).
That is, the processing means 50 refers to the state of the square wave signal hu of the square wave generation circuit 20 corresponding to the digital value at the time when the digital value is acquired in the step 1, and the state is an H signal or an L signal. Accordingly, it is determined whether the current time point is an output portion of a triangular wave having a downward slope or an upward slope.

Next, the processing means 50 collates the digital value acquired in Step 2 with the magnetic detection value number d on the data table DT, and uses the determination results in Step 3 and Step 4 as selection conditions. A matching magnetic detection value number d is selected from the data table DT (step 5). If there is no magnetic detection value number d that completely matches, the closest magnetic detection value number d is selected.
More specifically, the processing unit 50 first determines a specific pair on the data table DT according to the pole pair position range (pole pair 1, pole pair 2,... Or pole pair P) obtained in step 3. A data group (any one of G1, G2,... Gp) is selected.
Further, the processing means 50 determines a plurality of magnetic detection value numbers d (according to FIG. 7) according to the state of the triangular wave signal obtained in step 4 (downwardly inclined or upwardly inclined). "Xxx")), one magnetic detection value number d is selected. That is, in each data group (G1, G2,..., Or Gp) for each pole pair number, there are two identical magnetic detection value numbers d corresponding to the upward slope portion and the downward slope portion of the triangular wave. Any one of these two magnetic detection value numbers d is selected according to the determination in step 4.

Next, the processing means 50 acquires the rotor position number corresponding to the magnetic detection value number d selected as described above from the data table DT, and uses this rotor position number as the absolute rotational position of the rotor 11. (Step 6).
The absolute rotational position value is stored as a variable in a predetermined storage area of the storage means 51, and is updated each time a new absolute rotational position value is determined by the above steps.

The above-described processing (steps 1 to 7) is repeated at a constant interval (for example, the cycle Ts), and the absolute rotational position value updated at each repetition is used when the brushless DC motor 10 is sinusoidally driven. And used as a signal indicating the rotational position of the rotor 11.
That is, the processing means 50 acquires the absolute rotation position value, for example, every period Ts during the rotation of the brushless DC motor 10, and corrects the drive command for the inverter 60 each time the absolute rotation position value is acquired, thereby brushless. The phase and frequency of the drive current supplied to the DC motor 10 are appropriately changed.

Therefore, according to the rotational position detection device of the present embodiment, it is possible to improve the detection accuracy of the rotor position with a simple and low-cost configuration. As a result, when the brushless DC motor 10 is sine-wave driven, The rotor 11 can be smoothly rotated with high efficiency and low vibration.
It is also possible to control the rotational position of the brushless DC motor 10 with high accuracy using this rotational position detection device.

  The rotational position detection device is a brushless DC motor drive control and rotation for all devices such as industrial devices such as robots and conveyors, home appliances such as washing machines and refrigerators, and OA devices such as printers and copiers. It can be applied to position control.

  In the above embodiment, the data table DT (see FIG. 7) is created by the processing of the processing means 50. However, as another example, the data table DT can be created by experiments or calculations other than the above. is there.

  Further, in the above embodiment, the correspondence information between the rotor position number indicating the rotational position of the rotor 11 and the magnetic detection value number d, which is a numerical value corresponding to the detection value by the magnetic detection units Hu, Hv, Hw, is stored in the data table. Although it is stored in the storage means 51 as DT, as another example, it is possible to replace the data table DT and store the function expression indicating the correspondence information in the storage means 51.

  Further, according to the above-described embodiment, the plurality of magnetic detection units Hu, Hv, and Hw that are integrally incorporated in a general well-known brushless DC motor 10 are used. The DC motor 10 may be configured to include at least one magnetic detection unit that is integral with or separate from the DC motor 10.

  Further, according to the above embodiment, the brushless DC motor 10 having a plurality of pole pairs is shown as an example. However, as another example, the number of pole pairs of the brushless DC motor 10 may be singular. In this case, since the data table DT is single, it is not necessary to recognize the above-described pole pair position range and to select the data table DT, and the origin sensor 13 and the above step 3 can be omitted.

10: Brushless DC motor 11: Rotor 12: Stator 13: Origin sensor 20: Square wave generation circuit 30: Triangular wave generation circuit 40: A / D conversion circuit 50: Processing means 51: Storage means 60: Inverter Hu, Hv, Hw: Magnetic detector DT: Data table (correspondence information)
d: Magnetic detection value number

Claims (5)

A magnetic detection unit that detects a magnetic change in the vicinity of the rotor that rotates the magnetic pole, a square wave generation circuit that converts the output signal of the magnetic detection unit into a square wave signal, and a square wave signal of the square wave generation circuit that is a triangular wave signal A triangular wave generation circuit that converts the triangular wave signal of the triangular wave generation circuit into a digital signal, a square wave signal of the square wave generation circuit, and a digital signal of the A / D conversion circuit, respectively Rotational position provided with processing means for inputting, and storage means for preliminarily storing correspondence information between a rotor position number indicating the rotational position of the rotor and a magnetic detection value number that is a numerical value corresponding to a detection value by the magnetic detection unit A detection device,
The processing means obtains the magnetic detection value number corresponding to the digital value of the A / D conversion circuit from the correspondence information according to the state of the square wave signal of the square wave generation circuit, and further detects the magnetic detection value. A rotational position detecting device characterized in that a rotor position number corresponding to a number is obtained and the rotor position number is output as an absolute rotational position value.   The correspondence information is a plurality of rotor position numbers in which values indicating the rotational positions of the rotor are arranged in order, and numerical values corresponding to the plurality of rotor position numbers and corresponding to detection values by the magnetic detection unit. 2. The rotational position detection device according to claim 1, wherein the rotation position detection device is a data table having a plurality of magnetic detection value numbers.   The processing means selects the magnetic detection value number corresponding to the output value of the triangular wave generation circuit from the data table according to whether the square wave signal is an H signal or an L signal, and the selected magnetic detection The rotational position detection device according to claim 2, wherein the rotor position number corresponding to the value number is the absolute rotational position value. The data table includes a plurality of rotor position numbers and magnetic detection value numbers grouped into data groups for each pole pair number corresponding to a rotor pole pair,
The processing means acquires the origin position of the rotor by an origin sensor, counts the period of the square wave signal from this acquisition time point, recognizes the position range of the pole pair according to the count value, and detects the pole pair position. 4. The rotational position detection device according to claim 3, wherein the data group of the pole pair number corresponding to a range is selected from the data table. A brushless DC motor in which the magnetic detection unit is provided in the vicinity of the rotor, and an inverter circuit for supplying electric power to the brushless DC motor,
5. The brushless DC motor sine wave using the rotational position detection device according to claim 1, wherein the processing unit corrects a drive command to the inverter circuit in accordance with the absolute rotational position value. 6. Drive control device.

Images