JPH0698582A - Brushless dc motor - Google Patents

Abstract

PURPOSE:To provide a brushless DC motor which does not have a sensor and facilitates the optimum correction of a phase relation between a rotor and the rotating magnetic field of a stator winding during an ordinary rotation. CONSTITUTION:The revolution of a rotor 116 is detected by a frequency generator 101 to output a frequency signal. A direction detecting means 103 detects a rotating direction from the frequency signal. A counter means 106 performs a counting operation in accordance with the direction detection signal and the frequency signal. The counted value is converted into a waveform signal by a waveform generating means 109 and a rotating magnetic field corresponding to the waveform signal is induced in a stator winding 703 and the rotor 116 is driven to rotate. Further, the revolution of the rotor 116 is controlled at a required value by a rotation control means 112. By correcting the performance of the counter means 106 in accordance with the output signal of the rotation control means 112, a high efficiency brushless DC motor which does not have a sensor and shows little torque ripple can be realized.

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 A brushless DC motor has a long life because it does not have mechanical contacts as compared with a DC motor with a brush, and at the same time has less electrical noise. -Widely applied to 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. This is because 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 the preset current pattern corresponding to the count value is used as 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.
Japanese Patent Laid-Open No. 63-262088 has been proposed to meet such a demand.

[0005]

However, in the above-mentioned configuration, an error occurs in the count value of the counter means due to shaft loss or noise entering the output signal of the frequency generator. This counting error reduces the efficiency of the motor and also increases the torque ripple. For this reason, there are great restrictions on the application of the brushless DC motor, such as the inability to apply to a VTR capstan motor or the like that requires high precision rotation. Especially in a small motor, the decrease in efficiency becomes a big problem.

In Japanese Laid-Open Patent Publication No. 63-262088, a zero-cross point of the current flowing through the stator winding is detected and the counter circuit is reset to correct the count value of the counter means. ing. But,
It is difficult to correct the count value only by resetting the count value of the counter means at the zero crossing point of the fixed winding current. Further, there is a problem that the circuit becomes complicated because a current zero-cross point detection circuit is required.

In view of the above problems, it is an object of the present invention to provide a brushless DC motor configured so that the counting error can be corrected when the motor rotates.

Further, according to the present invention, the efficiency of the motor is kept high and the torque ripple is reduced.
An object of the present invention is to provide a brushless DC motor applicable to a wide range of purposes.

[0009]

In order to solve the above problems, a brushless motor according to the present invention has a rotor having a plurality of magnetic poles, and a plurality of phases fixed at a predetermined interval on the rotor. A child winding, a frequency generator that generates frequency signals of a plurality of phases proportional to the number of rotations of the rotor, and a direction detection unit that detects the rotation direction of the rotor by the frequency signals of the plurality of phases and outputs a direction detection signal. And a rotation control means for outputting a rotation control signal by a signal corresponding to at least one frequency signal to control the rotation of the rotor to a predetermined rotation speed, and a first detection circuit according to the direction detection signal and the at least one frequency signal. Addition / subtraction signal generating means for outputting the addition signal and the first subtraction signal, correction signal generating means for outputting the second addition signal and the second subtraction signal according to the value corresponding to the rotation control signal, and the first addition Signal and second An addition / subtraction signal synthesizing means for generating a third addition signal on the basis of the addition signal and a third subtraction signal on the basis of the first subtraction signal and the second subtraction signal; In accordance with the counter means for counting up according to the third subtraction signal and counting down according to the third subtraction signal and for setting the initial value of the counter by the initial count value, and the count value of the counter means and the rotation direction detection signal. Initial position detecting means for outputting the digital value and the initial count value, and phase adjusting means for adding and subtracting a predetermined value from the value corresponding to the first digital value according to the rotation direction command and outputting the second digital value. Waveform generating means for generating waveform signals of a plurality of phases according to the second digital value and the rotation control signal, and power for supplying power to the stator windings according to the waveform signals of the plurality of phases to generate a rotating magnetic field. And a supply means Than it is.

[0010]

According to the present invention having the above-mentioned structure, the correction signal generating means detects the counting error of the counter means by monitoring the rotation control signal, and the second addition signal or the second subtraction is performed according to the rotation control signal. By outputting the signal, the counting error of the counter means is corrected. When the error of the count value of the counter means increases, the magnitude of the rotation torque generated in the rotor decreases with respect to the magnitude of the rotation control signal.
Therefore, the rotation control signal has a large value in order to rotate the rotor at a constant rotation. Therefore, the count value of the counter means can be corrected by monitoring the rotation control signal by the correction signal generating means.

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 wires 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.

[0012]

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. 7 (a) shows a configuration diagram of a rotor and a stator winding of a flat type brushless DC motor. In FIG. 7A, the rotor 116 that rotates together with the rotating shaft 701.
Are arranged to face the stator 702. Rotor 116
As shown in FIG. 7B, a plurality of poles (here, 8 poles) are arranged in a disk shape at equal intervals along the circumferential direction. Further, as shown in FIG. 7C, the stator 702 is composed of a plurality of flat windings (here, six) which are arranged in a disk shape at equal intervals on a plane with the rotating shaft 701 as a center. The flat windings separated by 180 degrees from each other are connected to each other, and the three-phase stator windings 703a, 703b, 703c are connected.
Are configured.

Next, the principle of rotation torque generation of the brushless motor shown in FIG. 7 will be described. FIG. 8 shows the stator winding 703.
An example of the waveform of the current flowing through a, 703b, and 703c is shown. Current waveforms Ia, Ib, and Ic in FIG. 8 are waveforms of currents flowing in the stator windings 703a, 703b, and 703c, respectively. FIG. 9 shows the magnetic poles of the rotor 116 and the stator winding 703.
The relative positional relationship of a, 703b, and 703c is shown.

First, in the initial state, the rotor 116 and the stator windings 703a, 703b, 703c are shown in FIG. 9 (a).
It is in the state of. At this time, when the current signal when θ = 0 in FIG. 8 (currents Ia, Ib, and Ic when θ = 0) is supplied to the stator windings 703a, 703b, and 703c, the flowing direction of the current and the rotational torque. FIG. 9A shows the direction in which the noise occurs. In this case, the rotor 116 receives rotational torque in the reverse rotation direction (rightward in the figure) as shown in FIG.
Rotate in the opposite direction.

Next, in the initial state, the rotor 116 and the stator windings 703a, 703b, 703c are shown in FIG. 9 (b).
It is in the state of. At this time, FIG. 9B shows the current flow direction and the rotational torque generation direction when the current signal of θ = 0 in FIG. 8 is supplied to the stator windings 703a, 703b, 703c. In this case, the rotor 116 is shown in FIG.
As shown in (b), it receives a rotational torque in the forward rotation direction (leftward in the figure) and rotates in the forward direction.

Further, in the initial state, the rotor 116
And stator windings 703a, 703b, 703c are shown in FIG.
It is assumed that the state is (c). At this time, when the current signal of θ = 0 in FIG. 8 is supplied to the stator windings 703a, 703b, 703c, the rotational torque becomes zero. That is, θ in FIG.
= 0 current signal to the stator windings 703a, 703b, 70
3c, rotor 116 and stator winding 703
Finally, a, 703b and 703c are in the state shown in FIG. 9 (c). In the state of FIG. 9C, even if the position of the rotor 116 moves to the left or right, the rotational torque is generated so as to return to the state of FIG. 9C.

Below, when the magnetic pole direction of the rotor 116 and the magnetic pole direction of the rotating magnetic field of the stator winding 703 are in the state of FIG. 9C, the magnetic pole direction of the rotor 116 and the rotating magnetic field of the stator winding 703 are shown. It is called a state in which the magnetic pole directions of are in agreement.

Next, with the magnetic pole direction of the rotor 116 and the magnetic pole direction of the rotating magnetic field of the stator winding 703 being aligned,
The operation of generating the rotational torque when the current signal of the stator winding 703 is changed will be described.

FIG. 10A shows a state in which the magnetic pole direction of the rotor 116 and the magnetic pole direction of the rotating magnetic field of the stator winding 703 coincide with each other. In FIG. 10B, the stator winding 703 has θ shown in FIG.
The direction of the rotational torque of the rotor 116 when a current signal of 90 degrees is supplied is shown. As shown in FIG.
When a current signal of 90 degrees is supplied, the rotor 116 receives a rotational torque in the positive direction and rotates in the positive direction. In addition, FIG.
FIG. 8C shows the current direction of the stator winding 703 when the current signal of θ = 180 degrees in FIG. 8 is supplied to the stator winding 703. In this state, the rotation torque of the rotor 116 is zero. However, when a disturbance torque is applied to the rotor 116 from the outside in the forward direction or the reverse direction,
A rotational torque is applied in a direction away from the state of (c).
That is, when the disturbance torque of the reverse rotation is received, the rotation torque of the opposite direction is received to rotate in the reverse direction, and when the disturbance torque of the forward rotation is received, the rotation torque of the forward direction is received to rotate in the forward direction. Therefore, this state is unstable, and the rotation direction of the rotor 116 is also uncertain. FIG. 10D shows the direction of the rotation torque of the rotor 116 when the current signal of θ = −90 degrees (270 degrees) in FIG. 8 is supplied to the stator winding 703. As shown in FIG. 10D, θ = −90 degrees (270
When a current signal of 10 degrees) is supplied, the rotor 116 receives rotational torque in the opposite direction and rotates in the opposite direction.

Therefore, by operating the current signal supplied to the stator winding 703 in a state where the magnetic pole direction of the rotor 116 and the magnetic pole direction of the rotating magnetic field of the stator winding 703 match, the rotor 116 is positively moved. It is possible to rotate freely in either direction or in the opposite direction.

Further, in FIG. 8, θ = 90 degrees or θ = −90
When a current signal of 10 degrees is supplied, the efficiency is maximized and the torque ripple is minimized, so that highly accurate rotation can be obtained.

FIG. 1 shows a block diagram of the brushless DC motor of the present invention. In FIG. 1, the frequency generator 101 outputs frequency signals m1 and m2 Z times per rotation of the rotor 116 (Z is referred to as the number of teeth, and here Z = 360 × 4).
To occur. The frequency signals m1 and m2 have a phase that is 90 degrees ahead of the frequency signal m2 when the rotor 116 is rotating in the positive direction, and the frequency signal m1 is the frequency when rotating in the reverse direction. It has a phase delayed by 90 degrees from the signal m2. The waveform shaping circuit 102 outputs the frequency signal m
1 and m2 are waveform-shaped and rectangular wave signals a1 and a2 corresponding to them are output. The direction detection circuit 103 detects the rotation direction of the rotor 116 from the two-phase rectangular wave signals a1 and a2.

A concrete structure of the direction detection circuit 103 is shown in FIG.
Shown in. In FIG. 2, the rectangular wave signal a1 is input to the data input terminal D of the data input type flip-flop circuit 21, and the rectangular wave signal a1 is input to the clock input terminal CK. FIG. 3A shows the waveforms of the rectangular wave signals a1 and a2 when the rotor 116 is rotating in the positive direction. The data input type flip-flop circuit 21 holds the state of the data input terminal D at each rising edge of the signal input to the clock input terminal CK and outputs the state as an output terminal of the data input type flip-flop circuit 21. Output from Q. With this operation, when the rotor 116 is rotating in the forward direction as shown in FIG. 3A, the output of the data input type flip-flop circuit 21 is always in a high potential state (hereinafter, this state "H"). In addition, the rectangular wave signal a when the rotor 116 is rotating in the reverse direction
1 and a2 are shown in FIG. When the rotor 116 is rotating in the reverse direction, the phase of the rectangular wave signal a1 lags behind the rectangular wave signal a2 by 90 degrees as shown in FIG. In this case, the output of the data input type flip-flop circuit 21 is always in the low high potential state (hereinafter, this state is referred to as "L"). Therefore, the rotation direction of the rotor 116 can be detected by configuring the direction detection circuit 103 as shown in FIG.
The direction detection signal rd, which is the output signal of the direction detection circuit 103, indicates that when the rotor 116 is rotating in the forward direction,
rd = “H”, and rd = “L” when the rotor 116 is rotating in the opposite direction. The direction detection signal rd is input to the initial position detector 107 and the addition / subtraction signal generator 104 described later. Further, the rectangular wave signal a1 is input to the addition / subtraction signal generator 104.

In the addition / subtraction signal generator 104, the rotor 11
When 6 is rotating in the forward direction (direction detection signal rd is "
(When H ″), the rectangular wave signal a1 is used as the first addition signal u1.
And outputs "H" as the first subtraction signal d1. Further, when the rotor 116 is rotating in the reverse direction (when the direction detection signal rd is “L”), the rectangular wave signal a1 is output as the first subtraction signal d1 and the first addition signal u1 is output. H "is output. The addition / subtraction signal synthesizer 105 synthesizes a pulse of a second addition signal u2 and a pulse of the first addition signal u1 which will be described later and outputs them as a third addition signal u3.
Further, the pulse of the second subtraction signal d2 and the pulse of the first subtraction signal d1 which will be described later are combined and output as a third subtraction signal d3. The counter circuit 106 is an N-ary system (N is the number of teeth Z
And the number of magnetic poles of the rotor, here N = 360
And ) Up-down counter, the content is incremented by 1 each time a pulse of the third addition signal u3 arrives,
Also, the content is decremented by 1 each time the pulse of the third subtraction signal d3 arrives. Then, the counter value is output as the count value cd. The count value cd is input to the initial position detector 107.

The initial position detector 107 outputs a first digital signal cd1 according to the logic of the direction detection signal rd of the direction detection circuit 103 when the power is turned on, and during normal rotation (the rotor 116 continuously rotates). Count value cd
Is output as a first digital signal cd1. Specifically, when the power is turned on, first, the first digital signal cd1 is output so that the current signal when θ = 0 degrees in FIG. 8 is obtained. As a result, the rotor 116 receives torque and rotates. Next, the rotation direction of the rotor 116 is determined from the direction detection signal rd, and the first digital signal cd1 is output so that a rotating magnetic field in the direction opposite to the rotation direction of the rotor 116 is obtained. This operation is repeated until the logic of the direction detection signal rd is inverted (until the rotation direction of the rotor 116 changes).
To do. Then, the first digital signal cd1 is output as the initial count value sd. After the initial count value sd is output, the process proceeds to the normal rotation operation process, and the count value cd is output as the first digital value.

In the phase adjuster 108, when the power is turned on, the initial position detector 107 outputs the first digital signal cd1 as the second digital signal (waveform digital signal) pd because of the initial position detecting operation. Then, when the direction command rm input to the direction command input terminal 113 is "L" (when the direction command is the reverse rotation command), the digital value obtained by subtracting 90 from the first digital signal cd modulo 360 is calculated as the first value. 2 digital signal pd is output. That is, after subtracting 90 from the first digital signal cd, when the digital value becomes a negative value, 360 is added to the negative value (the result of the subtraction is
Do not add when the value is positive). Further, when the direction command rm input to the direction command input terminal 113 is "H" (when the direction command is the forward rotation command), the first digital signal cd1 has a value of 3
The digital value obtained by adding 90 modulo 60 is output as the second digital signal pd. That is, after adding 90 to the first digital signal cd1, the digital value becomes 360.
When it becomes the above value, it is 360 from the value of 360 or more
Is subtracted (if the result of the addition is less than 360, the subtraction is not performed). When such calculation is performed, the digital value of the second digital signal pd becomes an integer value from 0 to 359. The second digital signal pd is input to the waveform generator 109. In the waveform generator 109, the second digital signal p
Waveform signals p1, p2, p3 are output according to d and the rotation control signal e1 of the rotation controller 112. Waveform generator 1 shown in FIG.
09 shows a configuration diagram of 09.

The configuration and operation of the waveform generator 109 will be described below. The waveform generator 109 includes three ROMs (read only memories) 601a, 601b and 601c in which sinusoidal signals are stored in advance and three ROMs 6
Convert each digital value of 01 into an analog signal 3
D / A converter (digital / analog converter) 602
a, 602b, 602c, an analog signal of the D / A converter 602, and a rotation control signal e of the rotation controller 112 (described later).
It is composed of multipliers 603a, 603b, 603c for multiplying by 1 and outputting waveform signals p1, p2, p3. Note that the data of the sinusoidal signal in the ROM 601a has a phase delay of 120 degrees from the data of the ROM 601b, and the data of the sinusoidal signal in the ROM 601b is R
The phase is 120 degrees behind the data in the OM 601c. That is, the sinusoidal data in the three ROMs 601 are set so that their phases differ from each other by 120 degrees. Moreover, when the digital value of the second digital signal pd changes from 0 to 359, the phase of the output value of the ROM 601 is set to change from 0 degree to 359 degrees. The second digital signal pd is stored in the three ROMs 601a,
601b and 601c, the second digital signal p
The data corresponding to d is from the ROM 601 to the D / A converter 6
It is output to 02. Then, the multiplier 603 multiplies the output signal of the D / A converter 602 and the rotation control signal e1 of the rotation controller 112. Then, the multiplier 603 outputs the waveform signals p1, p2, p3 corresponding to the second digital signal pd and the rotation control signal e1. As described above, the waveform generator 109 is constituted by the ROM (memory means) 601, the D / A converter (digital-analog conversion means) 602, and the multiplier (multiplication means) 603.

The waveform signals p1, p2 and p3 are supplied to the power supply 1
10, the power-amplified drive currents Ia, Ib,
Ic is supplied to the stator windings 703a, 703b, 703c. By supplying the drive currents Ia, Ib, Ic to the stator windings 703a, 703b, 703c, a rotating magnetic field is generated and the rotor 116 rotates.

The rotation controller 112 outputs a rotation control signal e1 to the waveform generator 109 so that the rotor 116 rotates at a predetermined rotation speed. Hereinafter, the configuration and operation of the rotation controller 112 will be described in detail. The rotation controller 112 measures the period of the rectangular wave signal a1 and calculates an error signal that is the difference between the measured period and the desired period. Rotor 11
When the rotation speed of 6 is lower than the predetermined rotation speed, the period of the rectangular wave signal a1 becomes large, and the error signal also becomes large. On the contrary, when the rotation speed of the rotor 116 is higher than the predetermined rotation speed, the period of the rectangular wave signal a1 becomes smaller,
The error signal is also small. Next, the error signal is multiplied by a gain of a predetermined magnitude and output as the rotation control signal e1.

With this structure, the rotation speed of the rotor 116 can be kept constant. First, when the rotation speed of the rotor 116 is low, a large positive value is output as the rotation control signal e1, so the waveform generator 109 and the power supply 1
10 supplies a large amount of electric power to the stator winding 703,
The rotor 116 accelerates. This restores the predetermined speed. Next, when the rotation speed of the rotor 116 is high, a small value or a negative value is output as the rotation control signal e1, so that the waveform generator 109 and the power supply 110 cause a small amount of power or deceleration to the stator winding 703. Such electric power is supplied, and the rotor 116 slows down. This restores the predetermined speed. In this way, the rotation speed of the rotor 116 is controlled to the predetermined rotation speed. During normal control, the rotation control signal e1 has a positive value because the load torque or the like exists in the rotor 116. Further, when the load torque of the rotor 116 is large, the magnitude of the rotation control signal e1 also becomes large. Further, even if the load torque is the same, the magnitude of the rotation control signal e1 increases if the efficiency of the motor deteriorates.

Further, in the rotation controller 112, the rotor 1
When the rotation speed of 16 is within the predetermined rotation speed range, the steady rotation signal TE is set to "H". When it is out of the predetermined rotation speed range, the steady rotation signal TE is set to "L". That is, when the rotation speed of the rotor 116 becomes steady, the rotation steady signal TE
"H" is output as.

The correction signal generator 111 is a rotation controller 11
The second rotation control signal e1 is input and the second addition signal u2 and the second subtraction signal d2 are output so that the magnitude of the rotation control signal e1 becomes small. The correction signal generator 111 is shown in FIG.
A specific configuration example of is shown. A / D converter (analog / digital converter) 401, arithmetic unit 402, ram memory (RAM: random access memory) 403 for storing necessary values at any time, and ROM memory (ROM: read only) storing predetermined programs and constants The memory) 404. FIG. 5 shows a flowchart showing a specific example of the program. Next, the operation will be described in detail. [Initial value setting unit 501] Initializes variables necessary for the subsequent processing in advance. [Operation control unit 502] The steady rotation signal TE of the rotation control unit 112 is input, and it waits for the steady rotation signal TE to become "H". When the steady rotation signal TE becomes “H”, the rotation control signal input unit 503 operates. That is, the rotor 11
It is waiting for the rotation control of 6 to reach a steady state. [Rotation control signal input unit 503] A /
The D converter 401 converts the digital signal E1 into a digital torque value TR. [Torque Value Averaging Unit 504] First, the digital torque value T
Take a time average of R. The digital torque value TR and the stored digital torque values TR1, TR2, TR3 are added, and the total value is divided by 4 to calculate the average digital torque value TRB. That is,

[0034]

[Equation 1]

The calculation of Next, the contents of the stored digital torque values TR1, TR2, TR3 are updated. That is,

[0036]

[Equation 2]

The calculation of The variables TR1 and TR
2 and TR3, the contents are initially set to zero by the initial value setting unit 501. [Correction amount setting unit 505] The average digital torque value TRB is compared with a predetermined torque value TRB_REF, and when the average digital torque value TRB is not larger, a variable value N representing the number of pulse outputs is set to a predetermined value N2 (here , N2 are positive integers of 1 or more). Also, the average digital torque value TRB
Is larger, the variable value N representing the number of pulse outputs is set to a predetermined value N1 (where N1 is a positive integer greater than or equal to N2). [Torque change amount calculation unit 506] Average digital torque value T
Calculate the amount of change in RB. Average digital torque value TRB
The average digital torque value TRB1 one timing before is subtracted from to calculate the digital torque change amount TRBD. That is,

[0038]

[Equation 3]

The calculation of The variable TRB1 is initially set to zero by the initial value setting unit 501. [Correction direction determination unit 507] Digital torque change amount TRB
The correction direction variable SW is set according to the size of D. When the value of the digital change amount TRBD is positive, the sign of the correction direction variable SW is inverted. When the value of the digital change amount TRBD is not positive, the sign of the correction direction variable SW is not inverted. The variable SW is initially set to 1 by the initial value setting unit 501. [Correction pulse output unit 508] According to the sign of the correction direction variable SW, the number of pulse signals corresponding to the value of the variable N is output as the second addition signal u2 or the second subtraction signal d2. When the correction direction variable SW is positive, the number of pulse signals corresponding to the value of the variable N is output as the second addition signal u2. When the correction direction variable SW is not positive, the number of pulse signals corresponding to the value of the variable N is output as the second subtraction signal d2. [Delay unit 509] Performs a delay operation for a predetermined time in preparation for the next process. After that, the operation of the operation control unit 502 is restored.

As described above, the rotor 116, the stator winding 703, the frequency generator 101, and the direction detection circuit (direction detection means) 1
03, an addition / subtraction signal generator (addition / subtraction signal generating means) 104, an addition / subtraction signal synthesizer (addition / subtraction signal synthesis means) 105, a counter circuit (counter means) 106, an initial position detector (initial position detection means) 107, and a phase adjuster ( Phase adjusting means) 1
08, a waveform generator (waveform generating means) 109, a power supply (power supply means) 110, a correction signal generator (correction signal generation means) 111, and a rotation controller (rotation control means) 112 constitute a brushless DC motor. ing.

Next, the operation at the time of normal rotation after the initial position detecting operation by turning on the power is completed will be described. Here, as an initial position, the magnetic pole direction of the rotating magnetic field of the stator winding 703 is 90 electrical degrees ahead of the magnetic pole direction of the rotor 116.
It is assumed that it is advanced. At this time, the rotor 116 receives a rotational torque in the positive direction with the rotating magnetic field and rotates in the positive direction. Depending on the rotation of the rotor 116, the frequency generator 101
A frequency signal is further generated, and the waveform shaping circuit 102 shapes the waveform of the frequency signal and outputs rectangular wave signals a1 and a2. In the rectangular wave signals a1 and a2, since the rotor 116 is rotating in the positive direction, the rectangular wave signal a1 has a phase of 9 from that of the rectangular wave signal a2.
0 degrees ahead. Therefore, the direction detection signal rd of the direction detection circuit 103 becomes "H".

The addition / subtraction signal generator 104 generates a direction detection signal r
Since d is "H", the rectangular wave signal a1 is output as the first addition signal u1. The first addition signal u1 is input to the addition / subtraction signal combiner 105, combined with the second addition signal u2, and output as a third addition signal u3. The counter circuit 106 counts up the number of pulses of the third addition signal u3. The count value of the counter circuit 106 is input to the initial position detector 107, and the first digital value cd
It is output as 1. The first digital value cd1 is corrected by the phase adjuster 108, output as the second digital value rd, and waveforms are generated as waveform signals p1, p2, and p3 whose phases are advanced by an amount corresponding to the rotation angle of the rotor 116. Bowl 1
It is output from 09. As a result, the rotating magnetic field generated by the stator windings 703 rotates by the amount by which the rotor 116 rotates in the positive direction, and the rotating torque is again generated in the rotor 116. In this way, the amount of rotation of the rotor 116 is detected, and the rotating magnetic field rotates by that amount, so that the rotor 116 continuously rotates in the positive direction.

Next, as an initial position, the stator winding 70
It is assumed that the magnetic pole direction of the rotating magnetic field No. 3 is delayed by 90 degrees in electrical angle from the magnetic pole direction of the rotor 116 in advance. At this time, the rotor 116 receives a rotating torque in the opposite direction to the rotating magnetic field,
Rotate in the opposite direction. A frequency signal is generated from the frequency generator 101 in accordance with the rotation of the rotor 116, and the waveform shaping circuit 1
02 waveform-shapes the frequency signal to obtain rectangular wave signals a1 and a2.
Is output. In the rectangular wave signals a1 and a2, since the rotor 116 is rotating in the opposite direction, the rectangular wave signal a1 is the rectangular wave signal a.
The phase is 90 degrees behind 2. Therefore, the direction detection signal rd of the direction detection circuit 103 becomes "L".

The addition / subtraction signal generator 104 generates the direction detection signal r
Since d is "L", the rectangular wave signal a1 is output as the first subtraction signal d1. The first subtraction signal d1 is input to the addition / subtraction signal combiner 105, combined with the second subtraction signal d2, and output as the third subtraction signal d3. The counter circuit 106 down-counts the number of pulses of the third subtraction signal d3. The count value of the counter circuit 106 is input to the initial position detector 107, and the first digital value cd
It is output as 1. The first digital value cd1 is corrected by the phase adjuster 108, output as the second digital value rd, and waveforms are generated as waveform signals p1, p2, and p3 whose phases are advanced by an amount corresponding to the rotation angle of the rotor 116. Bowl 1
It is output from 09. As a result, the rotating magnetic field generated by the stator winding 703 rotates by the amount by which the rotor 116 rotates in the opposite direction, and the rotating torque is again generated in the rotor 116. In this way, the amount of rotation of the rotor 116 is detected, and the rotating magnetic field rotates by that amount, whereby the rotor 116 continuously rotates in the opposite direction.

From the above, the stator winding 7 is set as the initial position.
The rotor 1 has a magnetic pole direction of the rotating magnetic field 03 and a magnetic pole direction of the rotor 116.
16 can be rotated in the forward or reverse direction.

Next, the operation of detecting the initial position will be described. When the power is turned on, the rotor 116 and the stator winding 703
Since the position or the count value of the counter circuit 106 is uncertain, the operation of initial position detection is required. At the time of initial position detection, first, the power is turned on and the waveform signals p1, p2, p3 corresponding to the first digital value cd1 of the initial position detector 107.
Is created. Then, a rotating magnetic field is generated by the stator winding 703, which causes the rotor 116 to rotate. The rotation direction depends on the angle between the magnetic pole direction of the magnetic field and the magnetic pole direction of the rotor 116. When the magnetic pole direction of the magnetic field is an electrical angle of 0 to 180 degrees with respect to the magnetic pole direction of the rotor 116, the rotor 116 rotates in the positive direction, and the magnetic pole direction of the magnetic field is relative to the magnetic pole direction of the rotor 116. When the electric angle is 0 to -180 degrees, the rotor 116 rotates in the opposite direction, and when the magnetic pole direction of the magnetic field is 0 degree with respect to the magnetic pole direction of the rotor 116, the rotor 116 When the magnetic field is stopped without receiving the rotational torque and the magnetic pole direction of the magnetic field is at an electrical angle of 180 degrees with respect to the magnetic pole direction of the rotor 116, the rotational direction is indefinite (the rotational direction cannot be specified).

Now, consider a case where the rotor 116 receives a rotational torque in the positive direction and rotates in the positive direction. At this time, a frequency signal is generated from the frequency generator 101 according to the rotation of the rotor 116, and the waveform is shaped by the waveform shaping circuit 102 to be rectangular wave signals a1 and a2. Square wave signals a1 and a
2, the phase of the rectangular wave signal a1 leads the rectangular wave signal a2 by 90 degrees because the rotor 116 rotates in the positive direction, and the direction detection signal rd of the direction detection circuit 103 becomes "L". In the initial position detector 107, since the direction detection signal rd is "H", the rotation direction of the rotating magnetic field generated by the waveform signals p1, p2, p3 is opposite to the rotation direction of the rotor 116.
Output the digital signal pd. Then, the initial position detector 107 performs this operation until the direction detection signal rd becomes "L". When the direction detection signal rd becomes "L", the first digital signal cd1 at that time is output as the initial count value sd, and the content of the counter circuit 106 is changed. The phase adjuster 108 outputs the second digital value pd without correcting the first digital value cd1 until the initial count value is output. Thereafter, the magnetic pole direction of the rotor 116 and the stator winding 703
The magnetic pole directions of the rotating magnetic field of are matched, and the rotor 116 stops rotating. Next, consider a case where the rotor 116 receives a rotational torque in the opposite direction and rotates in the opposite direction. At this time, a frequency signal is generated from the frequency generator 101 according to the rotation of the rotor 116, and the waveform is shaped by the waveform shaping circuit 102.
The rectangular wave signals a1 and a2 are obtained. The rectangular wave signals a1 and a2 are the same as the rectangular wave signal a because the rotor 116 is rotating in the opposite direction.
1 has a phase delayed by 90 degrees from the rectangular wave signal a2, and the direction detection signal rd of the direction detection circuit 103 becomes "L". In the initial position detector 107, since the direction detection signal rd is “L”,
The first digital signal pd is output so that the rotation direction of the rotating magnetic field generated by the waveform signals p1, p2, and p3 is opposite to the rotation direction of the rotor 116. And the initial position detector 1
07 performs this operation until the direction detection signal rd becomes "H". When the direction detection signal rd becomes "H", the first digital signal cd1 at that time is output as the initial count value sd, and the content of the counter circuit 106 is changed. The phase adjuster 108 outputs the first digital value c until the initial count value output.
The d1 is not corrected and is output as the second digital value pd. Thereafter, the magnetic pole direction of the rotor 116 and the stator winding 703
The magnetic pole directions of the rotating magnetic field of are matched, and the rotor 116 stops rotating.

Next, the magnetic pole direction of the rotating magnetic field and the rotor 116.
The operation of setting the initial phase relationship will be described from the state in which the magnetic pole direction of FIG. When the rotor 116 is rotated in the forward direction, the phase adjuster 108 adds a predetermined digital value (here, 90) to the first digital value cd1 modulo 360 to obtain a second digital signal. Output pd. As a result, the phases of the waveform signals p1, p2, and p3 advance by 90 degrees in terms of electrical angle, so that the initial phase position becomes the same as the above-described phase position during rotation in the positive direction, and the rotor 116 rotates in the positive direction. When the rotor 116 is rotated in the reverse direction, the phase adjuster 108 subtracts a predetermined digital value (here, 90) from the first digital value cd1 modulo 360. As a result, the waveform signal p1,
Since the phases of p2 and p3 are delayed by 90 degrees in electrical angle, the initial phase position becomes the same as the above-described phase position at the time of reverse rotation, and the rotor 116 rotates in the reverse direction.

As described above, the initial phase of the brushless DC motor is detected and the normal rotation operation is performed.

Once the phase is adjusted at the time of start-up, during the normal rotation, the rotation is performed while maintaining the initial phase state. But,
When noise or the like enters the frequency generator 101 and other circuits and signal lines, the initial phase relationship is broken. When the amount is large, fatal results such as stoppage and start-up failure of the rotor 116 occur. Therefore, the phase correction operation during normal rotation is essential.

Next, the phase correction operation during normal rotation will be described. First, a case where the count value of the counter circuit 106 has no error will be described. If there is no error in the count value of the counter circuit 106, the waveform signal p1,
The magnetic pole direction of the rotating magnetic field generated by p2 and p3 has a phase difference of 90 degrees in electrical angle with respect to the magnetic pole direction of the rotor 116. In this state, the efficiency of the motor is maximum, and the magnitude of the rotation control signal e1 is the smallest. Further, in this state, the ratio of the magnitude of the rotating torque generated in the rotor 116 to the electric power supplied to the stator winding 703 becomes maximum.

Next, a case where the count value of the counter circuit 106 has an error will be described. The rotating magnetic field is generated in the stator winding 703 by the electric power supplied to the stator winding 703 by the waveform generator 109 and the power supply 110, and the rotor 1
16 rotates. However, if there is a counting error in the count value of the counter circuit 106, the magnetic pole direction of the rotating magnetic field generated in the stator winding 703 does not maintain a phase difference of 90 degrees in electrical angle with respect to the magnetic pole direction of the rotor 116. Therefore, the ratio of the magnitude of the rotational torque generated in the rotor 116 to the electric power supplied to the stator winding 703 decreases. That is, the efficiency of the motor is reduced. As described above, when the rotation controller 112 controls the rotation speed of the rotor 116 to be constant with the efficiency lowered, the rotation control signal e1 is generated.
Is larger than when there is no counting error. That is,
When the efficiency of the motor decreases, the magnitude of the rotating torque generated in the rotor 116 decreases, so that the rotation speed of the rotor 116 decreases. When the rotation speed of the rotor 116 slows down, the rotation controller 112 works to increase the rotation control signal e1 to restore the rotation speed. As a result, the magnitude of the rotation control signal e1 increases as the efficiency of the motor decreases. In the correction signal generator 111, the torque command input unit 50
The rotation control signal e1 is input according to 3. The torque change amount calculation unit 506 determines whether the rotation control signal e1 is increasing or decreasing. If the rotation control signal e1 is decreasing, the correction direction determination unit 507 does not change the correction direction because the current correction direction is correct. However, if the rotation control signal e2 is increasing, the correction direction is changed because the current correction direction is incorrect. The correction pulse output unit 508 outputs the second addition signal u2 and the second subtraction signal d2 according to the correction direction variable SW.

Now, consider the case where a positive count error occurs in the count value of the counter circuit 106. When a positive counting error occurs, the efficiency of the motor decreases and the rotation control signal e1 increases. First, the rotation control signal input unit 503 of the correction signal generator 111 obtains the rotation control signal e1. In the torque change amount calculation unit 506, since the rotation control signal e1 has increased, the digital torque change amount TRBD has a positive value. In the correction direction determination unit 507, the digital torque change amount TRBD
Is a positive value, the sign of the correction direction variable SW is changed. The correction pulse output unit 508 outputs the second addition signal u2 or the second subtraction signal d2 according to the sign of the correction direction variable SW.

When the second subtraction signal d2 is output, this second subtraction signal d2 is input to the addition / subtraction signal synthesizer 105 and is input to the counter circuit 106 as the third subtraction signal d3. As a result, the count value of the counter circuit 106 is subtracted, and the positive count error is reduced. When the positive counting error becomes smaller, the efficiency of the motor is restored accordingly, and the rotation control signal e1 decreases. Correction signal generator 11
At 1, the torque change amount TRBD becomes negative due to the decrease of the rotation control signal e1. As a result, the correction direction variable SW
Since the sign of is not changed, the second subtraction signal d2 is output again. As a result, the counting error of the counter circuit 106 gradually decreases.

When the second addition signal u2 is output, this second addition signal u2 is input to the addition / subtraction signal synthesizer 105 and is input to the counter circuit 106 as the third addition signal u3. As a result, the count value of the counter circuit 106 is added, and the positive count error increases. When the positive counting error increases, the efficiency of the motor deteriorates accordingly, and the rotation control signal e1 increases. Correction signal generator 11
At 1, the torque change amount TRBD becomes positive and the sign of the correction direction variable SW changes due to the increase of the rotation control signal e1. Therefore, the second subtraction signal d2 is output. Accordingly, thereafter, the second subtraction signal d2 is output and the counting error of the counter circuit 106 is gradually reduced and corrected.

Now, consider the case where a negative count error occurs in the count value of the counter circuit 106. When the negative counting error occurs, the efficiency of the motor decreases, and the rotation control signal e1 increases. First, the rotation control signal input unit 503 of the correction signal generator 111 obtains the rotation control signal e1. In the torque change amount calculation unit 506, since the rotation control signal e1 has increased, the digital torque change amount TRBD has a positive value. In the correction direction determination unit 507, the digital torque change amount TRBD
Is a positive value, the sign of the correction direction variable SW is changed. The correction pulse output unit 508 outputs the second addition signal u2 or the second subtraction signal d2 according to the sign of the correction direction variable SW.

When the second addition signal u2 is output, the second addition signal u2 is input to the addition / subtraction signal synthesizer 105 and is input to the counter circuit 106 as the third addition signal u3. As a result, the count value of the counter circuit 106 is added, and the negative count error is reduced. When the negative counting error becomes smaller, the efficiency of the motor is restored accordingly, and the rotation control signal e1 decreases. Correction signal generator 11
At 1, the torque change amount TRBD becomes negative due to the decrease of the rotation control signal e1. As a result, the correction direction variable SW
Since the sign of is not changed, the second addition signal u2 is output again. As a result, the counting error of the counter circuit 106 gradually decreases.

When the second subtraction signal d2 is output, this second subtraction signal d2 is input to the addition / subtraction signal synthesizer 105 and is input to the counter circuit 106 as the third subtraction signal d3. As a result, the count value of the counter circuit 106 is subtracted, and the negative count error increases. When the negative counting error increases, the efficiency of the motor deteriorates accordingly, and the rotation control signal e1 increases. Correction signal generator 11
At 1, the torque change amount TRBD becomes positive and the sign of the correction direction variable SW changes due to the increase of the rotation control signal e1. Therefore, the second addition signal u2 is output. As a result, thereafter, the second addition signal u2 is output and the counting error of the counter circuit 106 is gradually reduced and corrected.

As described above, even if a count error occurs in the count value of the counter circuit 106, the count value is corrected by the function of the correction signal generator 111.

According to the configuration of this embodiment, even if a counting error occurs in the counter circuit 106 during normal rotation, it is corrected by the correction signal generator 111, and it is possible to realize a brushless DC motor with high efficiency and small torque ripple. . In this way, high efficiency and small torque ripple mean that
The application range of brushless DC motors will be greatly expanded.
For example, it can be used for a capstan motor of a VTR (video tape recorder).

Further, in the present embodiment, the correction signal generator 11
At 1, the value corresponding to the rotation control signal e1 is sampled, and the time change average value is used to calculate the torque change amount. As a result, the influence of noise or the like superimposed on the rotation control signal e1 can be removed. In addition, the correction amount setting unit 505
Accordingly, the number of pulses of the second addition signal u2 and the second subtraction signal d2 is set to be large when the rotation control signal e1 is large and small when the rotation control signal e1 is small. Accordingly, when the count error of the count value of the counter circuit 106 is large, the correction amount is increased,
Correction can be done quickly. Furthermore, in the present embodiment, the operation of the rotation controller 112 and the operation of the correction signal generator 111 are synchronized by the steady rotation signal TE, so that when the rotor 116 operates intermittently. Also, the correction operation can be performed with the above configuration.

In the present embodiment, the correction signal generator 11
As an input of 1, the rotation control signal e1 of the rotation controller 112
However, information on the magnitude of the signal such as the waveform signal p1 may be used, or information on the magnitude of the current flowing through the stator winding 703 may be used.

Further, in the present embodiment, a part is constituted by hardware, but an operation similar to the above-mentioned operation may be realized by software using a microprocessor. In this case, the circuit configuration becomes simpler than that of this embodiment. Further, although three D / A converters are used in the waveform generating means, they may be composed of one D / A converter and three SH circuits (sample-hold circuits). Furthermore, the waveform signal p
One of 1, p2 and p3 may be synthesized from the other two. And, needless to say, all of these improvements are included in the present invention. Besides, various modifications can be made without changing the gist of the present invention.

[0064]

As described above, according to the present invention, since the position detecting element such as the conventional brushless DC motor is unnecessary, 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.

Further, with the above configuration, the brushless DC motor of the present invention is corrected so that the phase relationship between the rotor and the stator winding is optimized during normal rotation, so that the torque ripple can always be improved with high efficiency. Therefore, a brushless DC motor applicable to a wide range of purposes can be easily constructed.
Moreover, since the phase sequence of the position signals can be easily switched, the rotation direction can be switched without the need for a position detection element such as a hall element.

[Brief description of drawings]

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

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

FIG. 3 is an explanatory view explaining the operation of the direction detector of FIG.

FIG. 4 is a configuration diagram showing a specific configuration example of the correction signal generator of FIG.

5 is a flowchart showing an example of a built-in program of the correction signal generator shown in FIG.

6 is a configuration diagram showing a specific configuration example of the waveform generator of FIG.

FIG. 7 is a configuration diagram showing a configuration of a rotor and a stator winding of a brushless DC motor according to an embodiment of the present invention.

FIG. 8 is a waveform diagram showing an example of a current waveform flowing in the stator winding of FIG.

FIG. 9 is an explanatory diagram illustrating a relative positional relationship between a rotor and a stator winding of a brushless DC motor according to an embodiment of the present invention.

FIG. 10 is an explanatory diagram illustrating a relative positional relationship between a rotor and a stator winding of a brushless DC motor according to an embodiment of the present invention.

[Explanation of symbols]

 101 Frequency Generator 103 Direction Detection Means 104 Addition / Subtraction Signal Generation Means 105 Addition / Subtraction Signal Synthesis Means 106 Counter Means 107 Initial Position Detection Means 108 Phase Adjustment Means 109 Waveform Generation Means 110 Power Supply Means 111 Correction Signal Generation Means 112 Rotation Control Means 116 Rotor 502 operation control means 503 rotation control signal input means 504 torque value averaging means 505 correction amount setting means 506 torque change amount calculation means 507 correction direction determination means 508 correction pulse signal output means 509 delay means 601 memory means 602 digital-analog conversion means 603 Multiplying means 703 Stator winding

Claims (14)

[Claims] 1. A rotor having a plurality of magnetic poles, a plurality of phases of stator windings arranged at a predetermined interval in the rotor, and a plurality of phases of frequencies proportional to the number of rotations of the rotor. A frequency generator that generates a signal, a direction detection unit that detects a rotation direction of the rotor by the frequency signals of the plurality of phases and outputs a direction detection signal, and a rotation control signal by a signal corresponding to at least one of the frequency signals. To output a first addition signal and a first subtraction signal in response to the direction detection signal and at least one of the frequency signals. On the basis of the signal generating means, the correction signal generating means for outputting the second addition signal and the second subtraction signal by the value corresponding to the rotation control signal, and the first addition signal and the second addition signal. Third addition signal And an addition / subtraction signal synthesizing means for generating a third subtraction signal based on the first subtraction signal and the second subtraction signal, and up-counting according to the third addition signal, Counter means for down-counting according to the subtraction signal, phase adjusting means for adding and subtracting a predetermined value from a value corresponding to the count value of the counter means according to a rotation direction command, and outputting a waveform digital value, and the waveform digital Waveform generating means for generating waveform signals of a plurality of phases according to a value and the rotation control signal, and power supply means for supplying power to the stator windings according to the waveform signals of the plurality of phases to generate a rotating magnetic field A brushless DC motor characterized by being constituted by 2. A rotor having a plurality of magnetic poles, a plurality of phases of stator windings arranged at a predetermined interval on the rotor, and a plurality of phases of frequencies proportional to the number of rotations of the rotor. A frequency generator that generates a signal, a direction detection unit that detects a rotation direction of the rotor by the frequency signals of the plurality of phases and outputs a direction detection signal, and a rotation control signal by a signal corresponding to at least one of the frequency signals. To output a first addition signal and a first subtraction signal in response to the direction detection signal and at least one of the frequency signals. On the basis of the signal generating means, the correction signal generating means for outputting the second addition signal and the second subtraction signal by the value corresponding to the rotation control signal, and the first addition signal and the second addition signal. Third addition signal And an addition / subtraction signal synthesizing means for generating a third subtraction signal based on the first subtraction signal and the second subtraction signal, and up-counting according to the third addition signal, Counter means for counting down according to the subtraction signal of the first counter and setting the initial value of the counter by the initial count value, and the first digital value and the initial value according to the count value of the counter means and the rotation direction detection signal. Initial position detecting means for outputting a count value, phase adjusting means for adding and subtracting a predetermined value from a value corresponding to the first digital value according to a rotation direction command, and outputting a second digital value, and the second Waveform generating means for generating waveform signals of a plurality of phases according to the digital value of the rotation control signal and power for supplying a rotating magnetic field to the stator windings according to the waveform signals of the plurality of phases. Supply means Brushless DC motor, characterized in that it is more configurations. 3. The correction signal generating means is configured to output a second addition signal and a second subtraction signal according to an average value of values corresponding to the rotation control signal. Alternatively, the brushless DC motor according to claim 2. 4. The correction signal generating means is configured to output a second addition signal and a second subtraction signal according to a value obtained by sampling a value corresponding to the rotation control signal at a predetermined timing. The brushless DC motor according to claim 1 or 2. 5. The correction signal generating means is configured to output a second addition signal and a second subtraction signal according to a time-series average value of values obtained by sampling values corresponding to the rotation control signal at a predetermined timing. The brushless DC motor according to claim 1 or 2, wherein the brushless DC motor is provided. 6. An amount by which the correction signal generating means up-counts or down-counts the content of the counter means by the second addition signal or the second subtraction signal according to the magnitude of the value corresponding to the rotation control signal. The brushless DC motor according to claim 1, wherein the brushless DC motor is configured to increase or decrease. 7. The rotation control means outputs a steady rotation signal when the rotation speed of the rotor is within a predetermined rotation speed range, and the correction signal generating means starts or stops the operation according to the steady rotation signal. The brushless DC motor according to any one of claims 1 to 5. 8. The phase adjusting means adds or subtracts a predetermined value from a second digital value in accordance with a rotation direction command to determine the phase of the rotating magnetic field generated by the stator winding from the phase of the magnetic pole of the rotor. The brushless DC motor according to claim 2, wherein the brushless DC motor is configured to rotate at an angle of 90 degrees. 9. The waveform generating means comprises memory means for storing a sinusoidal signal in advance, digital-analog converting means for converting a digital value read from the memory means into an analog value, and multiplying means. The brushless DC motor according to any one of claims 1 to 5. 10. The initial position detecting means performs an operation of outputting an initial count value when the power is turned on, and otherwise outputs the count value of the counter means as a first digital value. Brushless DC motor described. 11. An initial position detecting means, an addition / subtraction signal generating means, an addition / subtraction signal synthesizing means, a counter means, a correction signal generating means, a phase adjusting means and a waveform generating means are memory means for storing program data according to processing contents. 3. The brushless DC motor according to claim 2, further comprising: an arithmetic processing unit that executes processing according to the program data. 12. Addition / subtraction signal generating means, addition / subtraction signal synthesizing means, counter means, phase detecting means, correction signal generating means and waveform generating means, memory means for storing program data according to processing contents, and the program The brushless DC motor according to claim 1, wherein the brushless DC motor is configured by an arithmetic processing unit that executes processing in accordance with data. 13. The correction signal generating means includes an operation control means for controlling the operation of the correction signal generating means, a rotation control signal input means for inputting a value corresponding to a rotation control signal, and the rotation control signal input means. A torque change amount calculating means for calculating a change amount of a value corresponding to the output signal, a correction direction determining means for determining a correction direction corresponding to the change amount, a correction direction of the correction direction determining means, and the correction amount setting means. The correction pulse signal output means for outputting the second addition signal and the second subtraction signal in accordance with the correction amount and the delay means for controlling the operation timing of the correction signal generating means. The brushless DC motor according to claim 1 or 2. 14. The correction signal generating means includes an operation control means for controlling the operation of the correction signal generating means, a rotation control signal input means for inputting a value corresponding to a rotation control signal, and the rotation control signal input means. A torque value averaging means for calculating an average value of values corresponding to the output signal, a correction amount setting means for setting a correction amount according to the output signal of the torque averaging means, and an output signal of the torque averaging means. A torque change amount calculating means for calculating a change amount of a corresponding value, a correction direction determining means for determining a correction direction corresponding to the change amount, a correction direction of the correction direction determining means, and a correction amount of the correction amount setting means. 7. A correction pulse signal output means for outputting a second addition signal and a second subtraction signal in accordance with the above, and a delay means for controlling the operation timing of the correction signal generation means. Or brushless DC motor according to claim 2, wherein.