JPH06276780A - Brushless dc motor - Google Patents

Abstract

PURPOSE:To detect the initial position of a permanent magnet rotor with less rotation or vibration. CONSTITUTION:The rotation of a permanent magnet rotor 101 is detected with a frequency generator 102. A direction detector 105 detects the rotating direction. A speed detector 104 detects the rotating speed. An operator 106 outputs position signals p1, p2 and p3 corresponding to the rotating positions of the permanent magnet rotor 101. A power supply device 110 supplies the power corresponding to the position signal into a stator winding 111. Thus, the permanent magnet rotor 101 is driven and rotated. By using the detected direction signal and the detected speed signal in phase matching, the phase-matching operation of the permanent magnet rotor 101 required when the power supply is turned on can be realized in a short time with less rotating angle and vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a brushless DC motor which does not require a position detecting element for detecting the rotational position of a rotor.

[0002]

2. Description of the Related Art Brushless DC motors, which have no mechanical contacts as compared to brushed DC motors, have a long service life and little electrical noise, and in recent years, they have been used in industrial equipment requiring high reliability. Widely applied to video and audio equipment.

Conventionally, this type of brushless DC motor has been
A position detecting element (for example, a hall element) corresponding to a brush is used for switching the energizing phase of the stator winding. However, the position detection element itself is not inexpensive at all, and the cost of the brushless DC motor is significantly higher than that of the brush DC motor due to the complexity of adjusting the mounting position of the element and the increase in the number of wires. Further, since the position detecting element has to be mounted inside the motor, there are often restrictions on the structure of the motor. In recent years, motors used have become smaller and thinner along with the downsizing of equipment, and there is no more room for mounting position detecting elements such as Hall elements. Therefore, some brushless DC motors having no position detecting element such as a Hall element have been proposed.

Some brushless DC motors without such a position detecting element utilize output pulses of a frequency generator mounted on the motor. The counter counts the output pulses of the frequency generator that generates pulses according to the rotation of the rotor, and the drive current of a preset current pattern corresponding to the count value is applied to the three-phase stator winding. Is sequentially energized to rotate the rotor. However, since the initial positions of the stator winding and the rotor are indefinite when the power is turned on, it is necessary to determine the initial positions.

In order to meet such demands, the present applicant discloses in Japanese Patent Application No. 4-23491 that "a permanent magnet rotor having a plurality of magnetic poles and the permanent magnet rotor are arranged at a predetermined interval. A plurality of phase stator windings, a frequency generator that generates a plurality of phase frequency signals proportional to the number of revolutions of the permanent magnet rotor, and a rotation direction of the permanent magnet rotor by the plurality of phase frequency signals. At least one of the frequency generator and a direction detecting means for detecting a direction and outputting a direction detection signal.
Counter means for up-counting or down-counting the number of pulses of one frequency signal according to the direction detection signal; waveform generating means for generating a waveform signal of a plurality of phases according to the count value of the counter means; Power supply means for supplying electric power to the stator winding to generate a rotating magnetic field in accordance with a waveform signal, magnetic poles of the permanent magnet rotor and exciting magnetic poles of the stator windings of a plurality of phases when power is turned on are predetermined. Of the brushless DC motor, which is composed of a phase matching means for performing phase matching so as to satisfy the above relationship.

[0006]

However, in the above-mentioned structure, when the phase is adjusted by the phase adjusting means,
Depending on the initial position of the rotor, the rotor vibrates with a large amplitude. Therefore, in a VTR capstan motor or the like that directly or indirectly drives the magnetic tape, the magnetic tape suffers tape damage or the like, which is a fatal defect.

In view of the above problems, it is an object of the present invention to provide a brushless DC motor configured so that the vibration amplitude of the rotor at the time of phase matching can be made extremely small regardless of the initial position of the rotor. To do.

[0008]

In order to solve the above problems, a brushless motor of the present invention comprises a rotor having a plurality of magnetic poles and a plurality of phases arranged in the rotor with a predetermined gap. Stator windings, rotation information detecting means for generating rotation information signals of a plurality of phases according to the number of rotations of the rotor, rotation direction of the rotor is detected from the rotation information signals of the plurality of phases and a direction signal is output Direction detection means, speed detection means for detecting the rotation speed of the rotor from at least one rotation information signal, and position signals of a plurality of phases according to at least one rotation information signal, direction signal, and detection speed signal of the speed detection means. And an electric power supply means for supplying electric power to the stator windings in accordance with position signals of a plurality of phases.

Further, the arithmetic processing means detects the initial position of the rotor from the detected speed signal of the speed detecting means and the direction signal of the direction detecting means, and an initial position corresponding to the initial detection position of the phase adjusting operation means. The position detecting operation means generates a plurality of phase position signals in response to at least one rotation information signal and a direction signal having a set value, and operation selecting means selecting operation of the position detecting operation means and the phase adjusting operation means. It is a thing.

The phase matching operation means calculates the rotational acceleration of the rotor from the detected speed signal of the speed detecting means, and the phase signal corresponding to the calculated acceleration signal of the acceleration calculating means and the direction signal of the direction detecting means. The phase signal increasing / decreasing means for changing the direction signal, the phase signal saving means for saving a plurality of the phase signals according to the change of the direction signal, and the at least two phase signals saved in the phase signal saving means for the rotor. The configuration includes an initial position calculating means for calculating an initial position and a position signal creating means for creating a plurality of phase position signals according to the phase signals.

[0011]

According to the present invention, with the above-described structure, it is possible to detect the acceleration of the rotor by the acceleration calculating means and change the position signal in accordance with the acceleration during the phase matching operation. Therefore, it is possible to always output the optimum position signal according to the state of the rotor, and it is possible to extremely reduce the vibration width of the rotor during the phase matching operation regardless of the initial position of the rotor.

When this brushless DC motor is used, a position detecting element unlike the conventional brushless DC motor is not required, so that the complexity of adjusting the mounting position of the element and the number of wirings are reduced, and the cost is greatly reduced. Further, since it is not necessary to mount the position detecting element inside the motor, the motor is not restricted in structure and can be made extremely small and thin.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A brushless DC motor according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing the structure of a brushless DC motor according to an embodiment of the present invention. In FIG. 1, a permanent magnet rotor 101 and a three-phase stator winding 111
a, 111b, 111c are arranged as shown in FIG. In FIG. 13A, the permanent magnet rotor 101 that rotates together with the rotating shaft 1302 is arranged so as to face the stator 1301. The permanent magnet rotor 101 is shown in FIG.
As shown in (b), a plurality of poles (here, eight poles) are arranged in a disk shape at equal intervals along the circumferential direction. As shown in FIG. 13C, the stator 1301 is provided with a plurality of flat windings (here, six) arranged in a disk shape at equal intervals on a plane with the rotating shaft 1302 as the center. There is. The flat windings that are 180 degrees apart from each other are connected to each other, and the three-phase stator windings 111a, 11b, 111c are connected.
Are configured. The frequency generator (rotation information detecting means) 102 in FIG. 1 has a Z per rotation of the permanent magnet rotor 101.
The number of times (here, Z is 672) is detected, and two-phase frequency signals m1 and m2 having different phases proportional to the rotation of the permanent magnet rotor 101 are generated. The two-phase frequency signals m1 and m2 are input to the waveform shaper 103 and converted into rectangular wave signals s1 and s2, respectively, and then input to the direction detector (direction detecting means) 105. The direction detector 105 outputs a direction signal d according to the forward and reverse rotation directions of the permanent magnet rotor 101.

A specific configuration of the direction detector 105 is shown in FIG. In FIG. 2, the rectangular wave signal s1 is input to the data input terminal D of the data input type flip-flop circuit 21, and the rectangular wave signal s2 is input to the clock input terminal CK. The direction signal d is the flip-flop circuit 2
1 is output from the output terminal Q.

FIG. 3A shows the waveforms of the rectangular wave signals s1 and s2 when the permanent magnet rotor 101 is rotating in the positive direction. FIG. The waveforms of the rectangular wave signals s1 and s2 when rotating in the direction are shown.
The data input type flip-flop circuit 21 receives the rising edge of the signal input to the clock input terminal CK at each rising edge.
The state of the data input terminal D is held and the state is output from the output terminal Q.

Therefore, when the permanent magnet rotor 101 is rotating in the positive direction as shown in FIG. 3A, the output terminal Q of the data input type flip-flop circuit 21 is always in a high potential state (hereinafter, It is called "H" state). On the other hand, when the permanent magnet rotor 101 is rotating in the opposite direction,
Since the phase of the rectangular wave signal s1 is delayed by 90 degrees from the rectangular wave signal s2 as shown in (b), the output Q is always in the low potential state (hereinafter, referred to as "L" state).

By constructing the direction detector 105 as shown in FIG. 2, the rotation direction of the permanent magnet rotor 101 can be detected. That is, the direction signal d of the direction detector 105 is in the “H” state when the permanent magnet rotor 101 is rotating in the forward direction, and is in the “L” state when rotating in the reverse direction. .

Further, in FIG. 1, the rectangular wave signal s1 is input to the speed detector 104, and the detected speed signal b corresponding to the cycle of the rectangular wave signal s1 is obtained. FIG. 4 shows a specific configuration example of the speed detector 104. The rectangular wave signal s1 is input to the AND circuit 41 and the flip-flop circuit 42.
The clock pulse clk of the oscillation circuit 43 and the overflow output signal w of the counter circuit 44 are also input to the input side of the AND circuit 41. The oscillator circuit 43 is composed of a crystal oscillator, a frequency divider, and the like, and has a clock pulse clk (5M) that is considerably higher in frequency than the frequency of the rectangular wave signal s1.
Hz) is generated. The counter circuit 44 is a 12-bit up counter that counts up the content of the output pulse h of the AND circuit 41 each time it arrives. The overflow output signal w is "H" when the count content of the counter circuit 44 is less than or equal to a predetermined value, and w when the count content of the counter circuit 44 is greater than or equal to the predetermined value.
Changes to "L". The data input type flip-flop circuit 42 takes in the signal in the "H" state input to the data input terminal D by using the falling edge of the rectangular wave signal s1 as a trigger signal, and outputs its output signal q as "H". To (q
= "H"). Further, an arithmetic processing unit (arithmetic processing means) described later
When the reset signal t from 106 becomes "H", the internal states of the counter circuit 44 and the flip-flop circuit 42 are reset (b = "LLLLLLLLLLLLLL", w).
= “H”, q = “L”).

Next, the operation of the speed detector 104 shown in FIG. 4 will be described. Now, it is assumed that the counter circuit 44 and the flip-flop circuit 42 are reset by the reset signal t. When the rectangular wave signal s1 corresponding to the frequency signal m1 of the frequency generator 102 changes from “L” to “H”, the clock pulse clk of the oscillation circuit 43 is output as the output signal h of the AND circuit 41. The counter circuit 44 counts the output signal h and changes its internal state. When the rectangular wave signal s1 changes from "H" to "L", the output signal h of the AND circuit 41 becomes "L", and the counter circuit 44 holds its internal state. The flip-flop circuit 42 takes in the data "H" at the falling edge of the rectangular wave signal s1 and outputs its output signal q.
Is changed from "L" to "H".

The digital signal b of the counter circuit 44 is a value proportional to the (half) cycle length of the rectangular wave signal s1 of the waveform shaper 103, and a value inversely proportional to the rotation speed of the permanent magnet rotor 101. . Further, since the output signal q of the flip-flop circuit 42 is in the “H” state at each rising edge of the rectangular wave signal s1, it is possible to detect the arrival of the pulse of the rectangular wave signal m1 by monitoring the output signal q. You can The arithmetic processing unit 106, which will be described later, looks at the output signal q of the flip-flop circuit 42, inputs the detection speed signal b of the counter circuit 44 when q becomes “H”, and then outputs the reset signal t for a predetermined short time. The counter circuit 44 and the flip-flop circuit 42 are reset to the initial state by being kept at "H" for the next speed detection operation.

When the rotation speed of the permanent magnet rotor 101 is too slow, the internal state of the counter circuit 44 becomes a predetermined value or more because the period of the rectangular wave signal s1 of the waveform shaper 102 is long, so that The buffer output signal w changes from "H" to "
In some cases, the output signal h of the AND circuit 41 becomes "L", and the counter circuit 44 holds a predetermined large value, thereby prohibiting the counter circuit 44 from overflowing. There is.

Further, in FIG. 1, the arithmetic processing unit 106 includes an arithmetic unit 107, a memory 109, and three D / A converters 10.
8a, 108b, 108c, and the output signal q of the speed detector 104, the detected speed signal b, and the direction detector 1
By inputting the direction signal d of 05 and performing calculation processing by the program described later stored in the memory 109,
It outputs three position signals p1, p2, p3. The three position signals p1, p2, p3 of the arithmetic processor 106 are input to the power supply 110, and the power supply 110 receives the stator winding 1
Power is supplied to 11. Further, the internal operation of the arithmetic processor 106 is changed by the phase matching operation command signal st of the phase matching operation command input terminal 112 and the rotation direction command md of the rotation direction command input terminal 113 (described later). Therefore,
Permanent magnet rotor 101, frequency generator 102 (rotation information detecting means), speed detector 104 (speed detecting means), direction detector 105 (direction detecting means), arithmetic processor 106 (arithmetic processing means), and power supply device. A sensorless DC motor is constituted by 110 (power supply means).

FIG. 5 is a signal waveform diagram of each part during steady rotation of the brushless DC motor of the present invention. In FIG. 5, e
1, e2 and e3 are stator windings 111a and 111a, respectively.
It is a generated voltage waveform induced in b and 111c. p1,
p2 and p3 are three-phase position signals output from the arithmetic processing unit 106, and are output so as to have a substantially in-phase relationship with the generated voltage waveforms e1, e2, and e3, respectively, according to the rotational position of the permanent magnet rotor 101. To do. The position signals p1, p2, p3 have a sinusoidal signal waveform, and the power supply unit 110 power-amplifies the three-phase position signals p1, p2, p3, respectively, to generate a sinusoidal three-phase drive current i1, i2, i3. The stator winding 1
Supply to each phase of 11a, 111b, 111c. As a result, the stator winding 1 is driven by the three-phase drive currents i1, i2, i3.
A rotating magnetic field is generated in 11a, 111b, and 111c, and the permanent magnet rotor 101 receives a rotational force to rotate due to the interaction between the rotating magnetic field and the magnetic poles of the permanent magnet rotor 101.

FIG. 6 is a vector diagram showing the phase relationship between the magnetic pole vector of the permanent magnet rotor 101 and the magnetomotive force vector of the rotating magnetic field generated in the stator winding 111. In FIG. 6, Φ is a magnetic pole vector indicating the magnetic pole of the permanent magnet rotor 101, and I is a magnetomotive force vector indicating the rotating magnetic field generated in the stator windings 111a, 111b, 111c.

FIG. 6A shows the permanent magnet rotor 101 rotating in the positive direction, and FIG. 6B shows the permanent magnet rotor 1.
FIG. 4 is a vector diagram showing a phase relationship between a magnetic pole vector Φ and a magnetomotive force vector I when 01 rotates in the opposite direction.

The magnetic pole vector Φ obtains a rotational force by the interaction with the magnetomotive force vector I, and rotates in the direction shown in FIG.
Here, in order for the permanent magnet rotor 101 to continuously rotate, the magnetomotive force vector I is generated according to the rotation amount of the magnetic pole vector Φ.
Must be rotated in the direction shown. That is, the phase of the magnetomotive force vector I is always advanced in the rotational direction by a predetermined angle (preferably 90 degrees) from the phase of the magnetic pole vector Φ, the amount of rotation of the magnetic pole vector Φ is detected, and the magnetomotive force is detected according to the amount of rotation. It is necessary to rotate the vector I (the angle on the vector diagram showing the magnetic pole vector Φ and the magnetomotive force vector I is referred to as an electrical angle).

The memory 109 of the arithmetic processor 106 of FIG.
Is a ROM area (R
It is divided into an OM (Read Only Memory) and a RAM area (RAM: Random Access Memory) that stores a required value at any time. The arithmetic unit 107 performs a predetermined operation or arithmetic operation according to a program in the ROM area.

First, the phase matching operation command input terminal 112
The operation is switched according to the phase matching operation command st input to. FIG. 7 shows a specific example of a program that realizes this operation, and the operation will be described in detail below.

In step 71, the phase matching operation command input terminal 112 inputs the phase matching operation command.

In step 72, the subsequent operation is selected in accordance with the phase matching operation command input in step 71. That is, when the phase matching operation command indicates the phase matching operation,
The operation of the phase matching operation unit (process 73) is performed, and when the phase matching operation command indicates the position detection operation, the operation of the position detection operation unit (process 74) is performed.

In process 73, the phase matching operation section (phase matching operation means) is operated. That is, the initial position of the permanent magnet rotor 101 is detected. Then, the process returns to the process 71.

In process 74, the position detecting operation section (position detecting operation means) is operated. That is, the processing during steady rotation is performed. Then, the process returns to the process 71.

By performing the above operation, either the operation of the phase matching operation section or the operation of the phase detecting operation section is selected in accordance with the phase matching operation command st input to the phase matching operation command input terminal 112. It Here, the processing 71, the processing 72, the processing 73, and the processing 74 constitute an operation selecting unit (operation selecting means).

Next, the position detecting operation unit that realizes the operation when the permanent magnet rotor 101 is rotating steadily will be described. FIG. 8 shows a specific example of a flow chart of a program for realizing the operation of the position detecting operation unit, and the operation will be described in detail below.

In step 811, the initial count value c _o corresponding to the initial position detected by the phase matching operation unit described later is set as the initial value of the count variable c (c ← _co ). here,
A process 811 operates the initial count value setting unit (initial count value setting means).

In the process 812a, the output signal q of the flip-flop circuit 42 of the speed detector 104 is input and waits until the output signal q becomes "H". That is, the speed detector 104 monitors the arrival of the pulse of the rectangular wave signal s1. When the output signal q becomes "H", the operation of process 812b is performed.

In process 812b, the reset signal t is set to "H" for a predetermined time, and the counter circuit 44 of the speed detector 104 is set.
And the flip-flop circuit 42 is reset.

In the process 812c, the direction detector 105 is first used.
The direction signal d of the flip-flop circuit 42 is input.
Next, when the direction signal d is "H", that is, when the permanent magnet rotor 101 is rotating in the positive direction, the operation of process 812d is performed. On the other hand, when the direction signal d is "L", that is, when the permanent magnet rotor 101 is rotating in the opposite direction, the operation of process 812e is performed.

In the process 812d, 1 is added to the value of the count variable c. That is, the value obtained by adding 1 to the value of the count variable c is set as the new value of the count variable c (c ← c +
1). Then, the operation of processing 813a is performed.

In process 812e, 1 is subtracted from the value of the count variable c. That is, 1 from the value of the count variable c
The value obtained by subtracting is the value of the new count variable c (c ←
c-1). Then, the operation of processing 813a is performed.

Here, the process 812a, the process 812b, the process 812c, the process 812d, and the process 812e constitute a count value increasing / decreasing unit (count value increasing / decreasing means) 812. The count value increasing / decreasing unit increases / decreases the value of the count variable c according to the direction signal d.

In process 813a, first, the rotation direction command md of the rotation direction command input terminal 113 of the arithmetic unit 107 is input. Next, when the content of the rotation direction command md is the normal rotation command, the operation of processing 813b is performed. On the other hand, the rotation direction command m
When the content of d is a reverse rotation command, the operation of process 813c is performed.

In process 813b, the value obtained by adding the predetermined value (90) to the count variable c is set as the phase signal f. afterwards,
The process of process 821 is performed. Here, (90) is a value corresponding to 90 degrees when converted into the rotation angle of the magnetomotive force vector I generated in the stator winding 111, and is preferably given by the following equation.

[0045]

[Equation 1]

Here, p is the number of poles of the permanent magnet rotor 101, and Z is the number of detections per revolution of the permanent magnet rotor 101 detected by the frequency generator (rotation information detecting means) 102.

In the process 813c, the value obtained by subtracting the predetermined value (90) from the count variable c is set as the phase signal f. After that, the process 821 is performed.

Here, the processing 813a, the processing 813b, and the processing 813c constitute a phase adjusting unit (phase adjusting means) 813. Further, the phase adjusting unit 813, the count value increasing / decreasing unit (count value increasing / decreasing unit) 812, and the initial count value setting unit (initial count value setting unit) 811 constitute a counting unit (counting unit) 81.

In process 821, position signals p1, p2, p
3 in order to obtain R 3 in the memory 109 based on the phase signal f.
Three addresses a1, a2 and a3 for referring to the function table of the sine wave for one period provided in the OM area are calculated. That is, since the phases of the position signals p1, p2, p3 are shifted by 120 degrees,

[0050]

[Equation 2]

[0051]

[Equation 3]

[0052]

[Equation 4]

From the above, three address values a1, a2 and a3 are calculated. Note that (120) is a predetermined address value corresponding to 120 degrees, which is converted into the rotation angle of the magnetomotive force vector Φ. Then, the process of process 822 is performed.

In process 822, 3 obtained in process 821 is obtained.
Memory 109 based on one address value a1, a2, a3
Of the three-phase digital position signals dp1, dp2, d by referring to the sine wave function table stored in the ROM area of
Get p3. Then, the process 72 is performed.

In process 823, 3 obtained in process 822 is obtained.
FIG. 1 shows the digital position signals dp1, dp2, dp3 of the phases.
To the D / A converters 108a, 108b and 108c. In the D / A converters 108a, 108b, 108c,
The digital position signals dp1, dp2, dp3 are converted into analog values, and three-phase position signals p1, p2, p3 are converted.
Is output. Then, the process returns to the operation of 812a.

Here, processing 821, processing 822 and processing 8
A position signal generating unit (position signal generating means) 82 is constituted by 23 and 23.

By performing the above processing, the position signals p1, p2, p3 are generated in response to the rotation of the permanent magnet rotor 101.
Is output to the power supply unit 110. Then, in the power supply unit 110, the stator windings 111a, 111b, 111c
Are supplied with sinusoidal drive currents i1, i2, i3.

That is, the rectangular wave signals s1 and s2 are generated according to the rotation of the permanent magnet rotor 101. Direction detector 10
In 4, the direction signal d corresponding to the rotation of the permanent magnet rotor 101 is output from the rectangular wave signals s1 and s2. The count value increasing / decreasing unit 812 increases / decreases the count variable c according to the rectangular wave signal s1 and the direction signal d. Permanent magnet rotor 1
When 01 is rotating normally, the count variable c is increased, and when the permanent magnet rotor 101 is rotating backward, the count variable c is decreased. That is, the count variable c has a value corresponding to the rotation amount of the permanent magnet rotor 101. The position signal generator 82 outputs position signals corresponding to the count variable c as the position signals p1, p2, p3. For this reason,
The phase of the position signal rotates by an amount corresponding to the amount of rotation of the permanent magnet rotor 101.

In this way, the magnetomotive force vector I of the rotating magnetic field generated in the stator winding 111 and the permanent magnet rotor 10 are
The magnetic pole vector Φ of 1 can always maintain a predetermined phase difference as shown in FIG. Then, due to the interaction between the magnetomotive force vector I and the magnetic pole vector Φ, the permanent magnet rotor 101
Receives rotation force and continues rotation.

Here, it is assumed that the magnetic pole vector Φ coincides with the magnetomotive force vector I when the predetermined address value (90) is zero in the phase adjuster of FIG. Initial count value setting unit 8
The initial count value c _o of 11 is the counter variable c at this time.
Is the value of. The initial count value c _o is calculated by the phase matching operation unit described later.

On the other hand, in the phase adjuster 813 of FIG. 8, a predetermined value (9
0) is added and subtracted to calculate the phase signal f. By performing such calculation, the electrical angle phase difference between the magnetomotive force vector I of the stator winding 111 and the magnetic pole vector Φ of the permanent magnet rotor 101 is +90 degrees or −90 degrees depending on the rotation direction command md. The electrical angle phase difference of Therefore, the permanent magnet rotor 10 is rotated according to the rotation direction command md.
1 can be rotated forward or backward. That is, the rotation direction of the permanent magnet rotor 101 can be easily changed by changing the direction command md.

As described above, the magnetomotive force vector I of the stator winding 111 and the magnetic pole vector Φ of the permanent magnet rotor 101 always maintain a phase difference of 90 degrees as shown in FIG. Then, due to the interaction between the magnetomotive force vector I and the magnetic pole vector Φ, the permanent magnet rotor 101 receives the rotational force and continues to rotate.

However, since the value of the count variable c of the counter section is indefinite in the initial state when the power is turned on, it is necessary to calculate the initial count value c _o of the count variable c.

[0064] Hereinafter, will be described in detail the operation of the phase-alignment unit for calculating the initial count value c _o of the counter unit 87 by the brushless DC motor of the present invention.

In the phase matching operation section of FIG. 9, when the value of the count variable c is improper such as when the power is turned on, the direction detector 1
05 direction signal d and speed detector 104 detected speed signal b
The rotating magnetic field generated in the stator windings 111a, 111b, 111c is forcibly rotated in the forward and reverse directions in accordance with the above, and the rotational behavior of the permanent magnet rotor 101 at that time determines the position of the magnetic pole of the permanent magnet rotor 101. To detect.

Count value c when the power is turned on or in the counter section
The operation of the phase matching operation unit performed when is unsuitable will be described with reference to the basic flowchart shown in FIG.

In process 91, zero is set as the initial value of the variable k for counting the number of changes in the rotation direction of the permanent magnet rotor 101. That is, the value of the variable k is set to zero. afterwards,
The processing of processing 921 is performed.

In process 921, first, the output signal q of the flip-flop circuit 42 of the speed detector 104 is input. Next, the process is selected according to the state of the output signal q. That is, when the pulse of the rectangular wave signal s1 is input to the speed detector 104, the process of process 922 is performed. On the other hand, the output signal q
When is “L”, the process of process 934 is performed.

In process 922, first, the reset signal t is set to "H" for a predetermined time and the counter circuit 4 of the speed detector 104 is set.
4 and the flip-flop circuit 42 are reset. next,
Detection speed signal b of the counter circuit 44 of the speed detection unit 104
Is input to set the speed detection value S.

In step 923, the speed detection value S is subtracted from the speed detection value S _n-1 one timing before to calculate the acceleration value An (An ← S _n-1 -S). In addition, the speed detection value S is set to a new speed detection value S _n-1 one timing before (S _n-1
← S). Here, due to the structure of the speed detector 104 shown in FIG. 4, the detected speed value is large when the rotation speed of the permanent magnet rotor 101 is low, and the detected speed value is high when the rotation speed of the permanent magnet rotor 101 is high. It will be a small value. Therefore, when the speed of the permanent magnet rotor 101 is gradually increased by the positive acceleration, the value of the speed detection value S becomes smaller than the value of the speed detection value S _n-1 one timing before, and the acceleration value An is It will be a positive value. On the contrary, the permanent magnet rotor 101
When the speed gradually decreases due to negative acceleration, the value of the speed detection value S becomes larger than the value of the speed detection value S _n-1 one timing before, and the acceleration value An becomes a negative value.
From the above, the positive / negative sign of the acceleration of the permanent magnet rotor 101 can be detected by the positive / negative sign of the acceleration value An.

Here, processing 921, processing 922, and processing 9
An acceleration calculation unit (acceleration calculation means) 92 is configured with 23.

In process 931, the next process is selected according to the sign of the acceleration value An. That is, when the acceleration value An is positive, the operation of process 932 is performed. Also, the acceleration value An
When is a negative value, the operation of processing 933 is performed.

In process 932, a predetermined value (here, 5) is set as the value of the phase signal increase / decrease variable SP. Then, the operation of processing 934 is performed.

In process 933, a predetermined value (a positive integer smaller than the predetermined value in process 932, which is 1 here) is set as the value of the phase signal increase / decrease variable SP. afterwards,
The operation of processing 934 is performed.

In process 934, the direction signal d of the direction detector 104 is input. Then, the process of process 935 is performed.

In process 935, the next process is selected according to the state of the direction signal d. When the direction signal d is "H", that is, when the permanent magnet rotor 101 is rotating in the positive direction, the operation of process 936 is performed. Also, the direction signal d
Is "L", that is, when the permanent magnet rotor 101 is rotating in the opposite direction, the processing of step 937 is performed.

In process 936, the value of the phase increase / decrease variable SP is added to the value of the phase signal f. That is, the value obtained by adding the value of the phase increase / decrease variable SP to the value of the phase signal f is used as the new phase signal f.
And After that, the process 821 is performed.

In process 937, the value of the phase increase / decrease variable SP is subtracted from the value of the phase signal f. That is, the value obtained by subtracting the value of the phase increase / decrease variable SP from the phase signal f is used as the new phase signal f.
And After that, the process 821 is performed.

Here, processing 931 and processing 932 and processing 9
33, processing 934, processing 935, processing 936, and processing 93
7 together form a phase signal increasing / decreasing unit (phase signal increasing / decreasing means) 93. In the phase signal adjuster 93, the acceleration calculator 92
The increment of the value of the phase signal f is adjusted on the basis of the acceleration value An calculated in. That is, when the permanent magnet rotor 101 is accelerating at a positive acceleration, a large value is set as the increment of the phase signal f to increase the change rate of the phase signal f. Further, when the permanent magnet rotor 101 is decelerating at a negative acceleration, a small value is set as the increment of the phase signal f to reduce the change rate of the phase signal f.

In process 821, position signals p1, p2, p
3 is obtained, the memory 109 of FIG.
Three address values a1, a2 for referring to the function table of the sine wave for one period provided in the ROM area of
Calculate a3. That is, the position signals p1, p2, p3
Since the phases of are shifted by 120 degrees,

[0081]

[Equation 5]

[0082]

[Equation 6]

[0083]

[Equation 7]

From the three address values a1, a2, a3
To calculate. Note that (120) is a predetermined address value corresponding to 120 degrees, which is converted into the rotation angle of the magnetomotive force vector I. Then, the process of process 822 is performed.

In process 822, 3 obtained in process 821 is obtained.
Memory 109 based on one address value a1, a2, a3
Of the three-phase digital position signals dp1, dp2, d by referring to the sine wave function table stored in the ROM area of
Get p3. After that, the processing of processing 823 is performed.

In process 823, 3 obtained in process 822 is obtained.
FIG. 1 shows the digital position signals dp1, dp2, dp3 of the phases.
To the D / A converters 108a, 108b, 108c shown in FIG. D / A converters 108a, 108b, 108c
Then, the digital position signals dp1, dp2, dp3 are converted into analog values, and the position signals p1, p2, p3 as shown in FIG. 5 are output. After that, the processing of processing 951 is performed.

Here, processing 821, processing 822 and processing 8
The position signal generating unit (position signal generating means) 82 is constituted by 23.

In process 951, the direction signal d of the direction detector 104 is input. Then, the process of process 952 is performed.

In process 952, when the direction signal d input in process 951 has changed from one timing before, process 95
Process 3 is performed. Further, when the direction signal d has not changed from the timing one timing before, the process returns to the process of 921.

In process 953, first, 1 is added to the variable k. That is, the value obtained by adding 1 to the value of the variable k is set as the value of the new variable k. Next, the value of the phase signal f is sequentially stored in the storage area M [k] corresponding to the value of the variable k. That is,
The value of the storage area M [k] is set to the value of the phase signal f. After that, the processing of processing 954 is performed.

Here, processing 951, processing 952 and processing 9
53 and 53 form a phase signal storage unit (phase signal storage means) 95.

In the process 961, the magnitude of the value of the variable k is compared with a predetermined value k _max (here, k _max is an integer of 2 or more, preferably 2), and the magnitude of the value of the variable k is large. Time,
The processing of processing 962 is performed. When the value of the variable k is not large, the process returns to the process 921.

In processing 962, the storage area M [n] (n =
1, 2, ..., K _max ) to calculate the initial count value c _o based on the values stored in k _max . That is, the storage area M [n]
The initial count value _co is determined by calculating the arithmetic mean of the values stored in. Preferably, the initial stored value M
The initial count value _co is obtained by calculating the arithmetic mean from an even number of stored values excluding [1]. Particularly preferably, the stored values M [2] and M [3] are used to calculate the arithmetic mean to obtain the initial count value _co . That is, the initial count value _co is

[0094]

[Equation 8]

It is calculated as After that, the process returns to the process 71 of FIG. Here, the processing 961 and the processing 962 constitute an initial position calculation unit (initial position calculation means) 96.

By performing the above processing, the position of the permanent magnet rotor 101 can be detected, and the rotation amount of the permanent magnet rotor 101 at the time of detection depends on the initial position of the permanent magnet rotor 101. No, it can be extremely reduced.

This will be described below. With the above configuration, in the phase signal increasing / decreasing unit 93, the permanent magnet rotor 101
The phase signal f is decreased when the rotation direction is the forward direction, and the phase signal f is increased or decreased when the rotation direction is the reverse rotation. Since the position signal generator 82 outputs the position signal in accordance with the phase signal f, the magnetomotive force vector I rotates in the reverse direction when the magnetic pole vector Φ rotates forward, and the magnetic pole vector Φ rotates reversely. When it is rotating, it rotates forward. That is, the magnetomotive force vector rotates in the opposite direction to the rotation direction of the permanent magnet rotor 101.

Here, it is assumed that the magnetomotive force vector I is not rotated in the direction opposite to the rotation direction of the permanent magnet rotor 101,
Assuming that the signals are output at a constant phase, the magnetic pole vector Φ rotates due to the interaction with the magnetomotive force vector I, and finally the two vectors coincide, as shown in FIG. Thereby, the position of the magnetic pole vector Φ can be detected. However, the permanent magnet rotor 101 rotates by a maximum of 180 degrees depending on its initial position (FIG. 10A). In the embodiment of the present invention, the magnetomotive force vector I is rotated in the direction opposite to the rotation direction of the permanent magnet rotor 101. Therefore, the magnetomotive force vector I and the magnetic pole vector Φ are in phase with each other when the magnetic pole vector Φ is rotated less. This state is shown in FIG. That is, by rotating the magnetomotive force vector I in the direction opposite to the rotation direction of the magnetic pole vector Φ, the magnetic pole vector Φ and the magnetomotive force vector I coincide with each other when the rotation amount of the magnetic pole vector Φ is small. Can detect the position of the magnetic pole vector Φ in an extremely small number.

Further, by performing the above processing, the position of the permanent magnet rotor 101 can be detected with high accuracy even when a load torque is present in the permanent magnet rotor 101. This will be described below.

When the load torque of the permanent magnet rotor 101 is not zero, the magnetomotive force vector I and the magnetic pole vector Φ do not match, and the phase angle θ corresponding to the magnitude of the load torque is maintained. Moreover, the direction of the phase shift is determined by the permanent magnet rotor 10
When 1 rotates in the positive direction, the magnetic pole vector Φ deviates from the magnetomotive force vector I by the angle θ in the reverse direction as shown in FIG. 11A, and when the permanent magnet rotor 101 rotates in the reverse direction, As shown in (b), the magnetic pole vector Φ deviates from the magnetomotive force vector I by the angle θ in the positive direction.

Therefore, when the permanent magnet rotor 101 is under load, the position of the permanent magnet rotor 101 cannot be accurately detected only by passing a current of a predetermined phase through the stator winding 111. In the embodiment of the present invention, the magnetomotive force vector I is rotationally oscillated in the forward and reverse directions according to the rotating direction of the permanent magnet rotor 101, so that the permanent magnet rotor 101 is rotated.
The initial count value c _o corresponding to the position is calculated.
Therefore, the position of the permanent magnet rotor 101 can be detected with high accuracy. The details will be described below.

With the above structure, the permanent magnet rotor 101 rotates so that the magnetomotive force vector I rotates in the opposite direction to the rotating direction of the permanent magnet rotor 101. Further, the phase signal storage unit 95 stores the phase signal f each time the rotation direction of the permanent magnet rotor 101 changes. The state of the magnetomotive force vector I and the magnetic pole vector Φ at the j-th rotation direction reversal is shown in FIG. In FIG. 12A, the magnetic pole vector Φ was rotated counterclockwise, but it is the moment when the rotational direction is changed to clockwise by receiving the rotational force of clockwise rotation due to the interaction with the magnetomotive force vector I. Further, FIG. 12B shows a state of the magnetomotive force vector I and the magnetic pole vector Φ at the time of (j + 1) th (next) jth rotation direction reversal. In FIG. 12B, the magnetic pole vector Φ was rotated to the right, but it is the moment when the rotational direction is changed to the left by receiving the rotational force of the counterclockwise rotation due to the interaction with the magnetomotive force vector I. Here, the value of the phase signal f corresponding to the position of the magnetic pole vector Φ is θ _o , and the value of the phase signal f corresponding to the phase angle between the magnetomotive force vector I and the magnetic pole vector Φ in FIG. _j , and the value of the phase signal f corresponding to the phase angle between the magnetomotive force vector I and the magnetic pole vector Φ in FIG. 11B is θ _{j + 1} , the stored value M [j] is

[0103]

[Equation 9]

However, j is a positive odd number. Becomes And
When the calculation of the initial position calculation unit 96 is performed,

[0105]

[Equation 10]

It becomes By repeating the reversing operation of the permanent magnet rotor 101, the phase angle θ _j and the phase angle θ _{j + 1} become substantially equal in size. Therefore,

[0107]

[Equation 11]

And

[0109]

[Equation 12]

It becomes: Thus, the initial count value c _o of the counter unit 81 is obtained as a value corresponding to the initial position of the permanent magnet rotor 101.

Further, the stored value M [k] (k = 1, 1) of the phase signal f when the permanent magnet rotor 101 is rotated in the forward and reverse directions.
2, ..., K _max ), the initial count value c _o is calculated. _Therefore , even if the load torque increases, (Equation 1),
The magnitude of θ _j or θ _{j + 1} in (Equation 2) only increases, and the influence of the load torque can be eliminated by the calculation of (Equation 10).

Furthermore, in this embodiment, the initial count value c _o is calculated using the stored values M [2] and M [3] of the phase signal storage unit 95. The value of the stored values M [1] is dependent largely on the initial phase difference of the magnetic pole vector Φ and the magnetomotive force vector I, the initial phase difference is greater Including stored values M [1] in the calculation of the initial count value c _o Sometimes magnetic pole vector Φ
A large error occurs in the position detection of. Also, the stored value M
When using the values after [4], it is necessary to make the predetermined value k _max large. In this case, the permanent magnet rotor 101
Inverting operations must be performed a lot, and the phase matching time becomes significantly long. In this embodiment, the stored values M [2] and M
By using [3], both the position detection accuracy and the shortening of the phase alignment time are realized.

It is also possible to further improve the position detection accuracy by using a large number of stored values.

Further, in this embodiment, the acceleration detecting section 92
Thus, the acceleration of the permanent magnet rotor 101 is detected, and the rotational speed of the magnetomotive force vector I of the stator winding 111 is changed according to the acceleration. As a result, the vibration width at the time of phase matching becomes small regardless of the initial position of the permanent magnet rotor 101.
This will be described below.

First, consider a case where the rotational acceleration of the permanent magnet rotor 101 is not detected and the rotational speed of the rotating magnetic field of the stator winding 111 is kept constant. In this case, stator winding 1
Magnetomotive force vector I of the rotating magnetic field 11 and permanent magnet rotor 1
When the electrical angle with the magnetic pole vector Φ of 01 is about 180 degrees, the vibration width of the permanent magnet rotor 101 is extremely large. This is because the time from the start of rotation of the permanent magnet rotor 101 until it coincides with the magnetomotive force vector I of the stator winding 111 becomes longer, and the rotation angle of the permanent magnet rotor 101 becomes larger accordingly. As a result, a large vibration is generated. This is improved by increasing the rotation speed of the magnetomotive force vector I. However, if the rotation speed of the magnetomotive force vector I is increased, when the electrical angle between the magnetomotive force vector I and the magnetic pole vector Φ is small, the magnetomotive force vector I The overshoot angle (corresponding to θ _j in FIG. 12) becomes large. This increases the vibration of the permanent magnet rotor 101.

Therefore, the rotational speed of the magnetomotive force vector I is increased until the electrical angle of the magnetomotive force vector I and the electrical angle of the magnetic pole vector Φ match, and after that, the rotational speed of the magnetomotive force vector I is decreased. It is necessary to perform such an operation, and the vibration amplitude of the permanent magnet rotor 101 can be reduced.

On the other hand, until the electrical angle of the magnetomotive force vector I and the electrical angle of the magnetic pole vector Φ match, the permanent magnet rotor 101 receives the rotational torque and the rotational acceleration becomes a positive value. After that, the magnetic pole vector Φ goes too far, the rotational torque acts in the direction opposite to the rotational direction of the permanent magnet rotor 101, and the acceleration becomes negative.

In this embodiment, the rotational acceleration of the permanent magnet rotor 101 is detected by the acceleration calculating section 92, and the update rate of the position signal is changed by the phase signal increasing / decreasing section 93 and the position signal generating section 82. Therefore, the rotational speed of the magnetomotive force vector I of the stator winding 111 is changed by the rotational acceleration of the permanent magnet rotor 101.

That is, when the rotational acceleration of the permanent magnet rotor 101 is positive, the rotational speed of the magnetomotive force vector I generated by the position signals of a plurality of phases is increased, and when the rotational acceleration of the permanent magnet rotor 101 is negative, The rotation speed of the magnetomotive force vector I generated by the phase position signal is slowed.

As a result, in the present embodiment, the magnetomotive force vector I rotates faster until the electrical angle of the magnetomotive force vector I and the electrical angle of the magnetic pole vector Φ coincide with each other. Since the rotation becomes slow, the vibration amplitude of the permanent magnet rotor 101 becomes small regardless of the initial position.

By performing the operation of the phase matching operation section as described above, the initial count value c of the counter section is
_o can be detected with a small rotation amplitude of the permanent magnet rotor 101. Further, even when the permanent magnet rotor 101 is loaded, the position of the permanent magnet rotor 101 can be detected with high accuracy. Further, the vibration amplitude becomes extremely small regardless of the initial position of the permanent magnet rotor 101.

As described above, since the brushless DC motor of the embodiment creates the three-phase position signals based on the two-phase frequency signals output from the frequency generator and having different phases, a position detecting element such as a Hall element is used. Need not be provided.

Further, in this embodiment, the three-phase position signals are converted into three D / A converters 108a, 108 as shown in FIG.
b, 108c. However, after sequentially converting to an analog value by using one D / A converter, the obtained analog value is held by three sample hold circuits to
It goes without saying that it is also possible to output as a phase position signal.

Further, not only the function table of the sine wave of only one cycle is stored in the memory, but also the sine waves of the three phases are stored in the function tables respectively, and the position signals of the three phases are directly stored. Equivalent digital value to 3 D / A
It goes without saying that it is also possible to output to the converters 108a, 108b, 108c. Furthermore, in this embodiment,
Although it is limited to the three-phase motor, the number of phases is not limited to three and may be any phase.

Further, the arithmetic processing unit may be constituted by complete hardware so that it can perform the same operation as the above-mentioned program. Besides, various modifications can be made without changing the gist of the present invention.

[0126]

As described above, the present invention eliminates the need for a position detecting element such as the conventional brushless DC motor.
The complexity of adjusting the mounting position of the element and the number of wirings are reduced, and the motor can be made ultra-small and ultra-thin without any structural restrictions.

Further, the brushless DC motor of the present invention is
With the above configuration, the rotational vibration amplitude of the permanent magnet rotor during the phase matching operation becomes extremely small regardless of the initial position of the permanent magnet rotor, so that a brushless DC motor applicable to a wide range of applications can be configured.

[Brief description of drawings]

FIG. 1 is a block diagram of a brushless DC motor according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a specific configuration example of the direction detector shown in FIG.

FIG. 3 is an explanatory diagram explaining the operation of the direction detector shown in FIG.

FIG. 4 is a configuration diagram showing a specific configuration example of the speed detector shown in FIG.

5 is a signal waveform diagram of each part during steady rotation of the brushless DC motor of the present invention shown in FIG.

6 is a vector diagram showing a relationship between a magnetic pole vector Φ of a permanent magnet rotor and a magnetomotive force vector I generated by a stator winding during steady rotation of the brushless DC motor of the present invention shown in FIG.

FIG. 7 is a flowchart of an embodiment for performing processing of an operation selection unit.

FIG. 8 is a flowchart of an embodiment for performing processing of position detection operation.

FIG. 9 is a flowchart of an embodiment for performing processing of a phase matching operation.

FIG. 10 is a vector diagram of a magnetic pole vector Φ and a magnetomotive force vector I for explaining a rotation amount during a phase matching operation.

FIG. 11 is a vector diagram of a magnetic pole vector Φ and a magnetomotive force vector I for explaining a phase matching operation.

FIG. 12 is a vector diagram of a magnetic pole vector Φ and a magnetomotive force vector I for explaining a phase matching operation.

FIG. 13 is a diagram showing an arrangement of a permanent magnet rotor and a stator winding.

[Explanation of symbols]

 73 Phase Matching Operation Section 74 Position Detection Operation Section 81 Counter Section 82 Position Signal Creation Section 92 Acceleration Detection Section 93 Phase Signal Increase / Decrease Section 95 Phase Signal Storage Section 96 Initial Position Calculation Section 101 Permanent Magnet Rotor 102 Frequency Generator 104 Speed Detector 105 Direction Detector 106 Arithmetic Processor 108 Digital / Analog Converter 109 Memory 110 Power Supply 111 Stator Winding 811 Initial Count Value Setting Unit 812 Count Value Increasing Unit 813 Phase Adjusting Unit

Claims (6)

[Claims] 1. A rotor having a plurality of magnetic poles, a plurality of phases of stator windings arranged in the rotor with a predetermined gap, and a plurality of phases corresponding to the number of rotations of the rotor. Rotation information detecting means for generating a rotation information signal, direction detecting means for detecting a rotation direction of the rotor from the rotation information signals of the plurality of phases, and outputting a direction signal, and rotation based on at least one rotation information signal. Speed detection means for detecting the rotation speed of the child; arithmetic processing means for generating position signals of a plurality of phases according to at least one of the rotation information signal, the direction signal and the detection speed signal of the speed detection means; A brushless DC motor comprising: power supply means for supplying power to the stator windings in accordance with a phase position signal. 2. The arithmetic processing means corresponds to the phase matching operation means for detecting the initial position of the rotor from the detected speed signal of the speed detecting means and the direction signal of the direction detecting means, and the detected initial position of the phase matching operation means. The position detection operation means for generating the position signals of the plurality of phases according to at least one of the rotation information signal and the direction signal, and the operation of the position detection operation means and the phase adjustment operation means are selected. The brushless DC motor according to claim 1, wherein the brushless DC motor comprises an operation selecting means. 3. The phase matching operation means calculates the rotational acceleration of the rotor based on the detected speed signal of the speed detecting means, and the acceleration calculating means of the acceleration calculating means and the direction signal of the direction detecting means. Phase signal increasing / decreasing means for generating a phase signal, phase signal saving means for saving a plurality of the phase signals according to changes in the direction signal, and at least two phase signals saved in the phase signal saving means Initial position calculating means for calculating the initial position of the rotor from
The brushless DC motor according to claim 2, further comprising position signal generating means for generating position signals of a plurality of phases according to the phase signals. 4. An initial value of the position detecting operation means is set in accordance with a detected initial position of the phase adjusting operation means, and a count value is increased or increased in accordance with at least one of the rotational position signal and the direction signal of the direction detecting means. 7. A counting means for decreasing and outputting a phase signal according to the count value, and a position signal generating means for outputting position signals of a plurality of phases according to the phase signal of the counting means. 2. The brushless DC motor described in 2. 5. The phase signal increasing / decreasing means is configured to generate a phase signal whose changing speed changes according to the acceleration signal calculated by the acceleration calculating means and whose changing direction changes according to the direction signal of the direction detecting means. The brushless DC motor according to claim 3, wherein 6. The count means sets an initial count value setting means for setting an initial value according to the detected initial position of the phase matching operation means, and increases or decreases the count value according to at least one of the rotation information signal and the direction signal. 7. A count value increasing / decreasing means for decreasing, and a phase adjusting means for outputting a phase signal by adding or subtracting a predetermined value from the count value of the count value increasing / decreasing means according to a rotation direction command. 4. The brushless DC motor according to 4.