JPH01202192A - Brushless motor control device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a control device for a brushless motor having a position detection section for detecting the rotational position of a rotor.

2. Description of the Related Art A motor control device that detects the rotational speed of a motor using a speed detector and controls power supplied to the motor based on the detected signal is used in a capstan motor of a video tape recorder. A control device that controls such speed is required to sufficiently suppress fluctuations in rotational speed due to fluctuations in load torque.

In response to such requests, the applicant has filed a patent application filed in 1986-22.
In No. 9143, "a rotation sensor that generates an alternating current signal with a period corresponding to the rotational speed of a motor, and a digital signal corresponding to the period of the alternating current signal of the rotation sensor zq times per rotation of the motor (here, Zq is an integer of 4 or more), a compensating means for calculating and storing a gap in the digital signal of the speed detecting means to generate a control signal, and supplying electric power to the motor according to the control signal of the compensating means. The compensation means includes a rotation error detection means for detecting a rotation error E of the motor based on the digital signal of the speed detection means, and the speed detection means detects a new digital signal. a counting means that performs a counting operation corresponding to the obtained count value and generates a count value I whose modulus is Nx-L (here, Nx is an integer of 2 or more, and L is an integer of 4 or more); memory means for storing at least NxL digital values M[0] to M[NxL-1] in a rewritable RAM area; and an integer J that changes in accordance with the count value of the counting means; N spaced apart by at least L intervals of said memory means
x digital value group M [J-nL (mod N
xL)] (n=1°2,..., Nx), and a composite value calculation means (memory output value creation means) that calculates a composite value calculated by the composite value calculation means The digital value of the memory means corresponding to the count value (■) of the counting means is sequentially M[O] by an update value substantially corresponding to the sum of the composite value and the rotation error of the rotation error detection means.

an update storage means that updates and stores M[N, M[2], . . . in order, and adds and synthesizes the composite value calculated by the composite value calculation means and the current rotation error of the rotation error detection means. and a control signal generating means for generating the control signal.''

Problems to be Solved by the Invention The motor speed control device described above has the excellent effect that the frequency transfer function from fluctuations in load torque to fluctuations in rotational speed becomes O or extremely small in a specific frequency group. Ta. However, it is essential to use a large number of digital memories, typically 16
bits X 1024words -16kbit
s of memory is required. Although IC elements for memory are rapidly becoming cheaper due to improvements in semiconductor manufacturing technology in recent years, using a memory of as much as 15 kbits is undesirable because it causes a significant increase in cost.

Moreover, from the digital value M[0] of the memory means to M[NxL
-1] until a value corresponding to the rotational error is stored, it was found that a sufficient reduction effect on rotational speed fluctuations is not exhibited. Therefore, when the number of digital values in the memory means is large, there is a drawback that it takes a very long time to obtain the above effect.

SUMMARY OF THE INVENTION An object of the present invention is to provide a brushless motor control device that can sufficiently reduce speed fluctuations by using a small number of memories, and can also quickly reduce rotational speed fluctuations due to load torque fluctuations. This is what I did.

Means for Solving the Problems In order to achieve the above object, the brushless motor control device of the present invention includes a brushless motor having a position detection unit that detects the rotational position of the rotor, and a brushless motor that has a position detection unit that detects the rotational position of the rotor, rotation sensor means for generating a periodic alternating current signal; speed detection means for detecting a plurality of times per revolution of the brushless motor based on the alternating current signal of the rotation sensor means; compensation means for producing a control signal; and control of the compensation means. The compensation means includes a drive means for driving the brushless motor according to a signal, and an operation command means for instructing the operation content of the compensation means, and the compensation means converts the digital rotation error into the speed according to the detected digital signal of the speed detection means. A rotation error calculation means obtained for each detection operation of the detection means, a composite error creation means for obtaining a digital composite error by combining at least two or more digital rotation errors of the rotation error calculation means, Here, for each detection operation (Q is an integer of 2 or more), one of the plurality of digital storage values is sequentially converted into a value corresponding to the digital synthesis error and a composite value of at least one of the digital storage values. update storage means for updating and storing; control signal generation means for generating the control signal by combining the digital rotation error and at least one digital storage value; The motor has a rotational position detecting means for obtaining a digital value corresponding to the rotational position of the motor, and a control operation changing means for changing the contents of the control operation according to instructions from the operation commanding means, and when the instruction from the operation commanding means becomes a speed control operation. , detecting the storage position of the digital storage value of the update storage means corresponding to the rotational position of the brushless motor using the digital value of the rotational position detection means, and update storage operation of the update storage means from the storage position. It was designed to do this.

Further, it is preferable to detect the time point at which the digital value of the rotational position detecting means changes, and obtain a storage position corresponding to the digital value at the time point of change.

Furthermore, when transitioning to speed control operation according to instructions from the operation command means, first, the update storage means is not operated;
It is preferable to perform a control operation using the rotational error calculation means and the control signal generation means, and then, after a required period of time has elapsed, to also perform the operation of the update storage means.

Operation In the present invention, by adopting the above-described configuration, a high-performance brushless motor control device is realized with a small number of memories (1/Q). In addition, when the brushless motor speed control operation is transitioned, the rotational position of the brushless motor is detected by the rotational position detection means, and the update storage means corresponds to the rotational position by updating and saving the digital storage value. Digitally stored values could be used immediately, and the effect of reducing speed fluctuations could be obtained in a short period of time.

Furthermore, by detecting the time point at which the digital value of the rotational position detection means changes and obtaining a storage position corresponding to the digital value at the time of change, the number of states of the detected digital value of the rotational position detection means is updated by the storage means. Even if the number of storage locations is significantly smaller than the number of storage locations, the storage locations can be detected with high accuracy.

Furthermore, when transitioning to the speed control operation, first, the update storage means is not activated, and the control operation using the rotation error calculation means and the control signal generation means is performed, and then the control operation using the rotation error calculation means and the control signal generation means is performed. By configuring the system so that the update/storage means is operated later, it is possible to quickly bring down the effects of spike-like speed fluctuations at the moment when control is shifted to using digitally stored values.

Embodiment Hereinafter, a brushless motor control device according to an embodiment of the present invention will be described with reference to the drawings, taking a capstan motor of a video tape recorder as an example. FIG. 2 shows a configuration diagram representing an embodiment of the present invention. In FIG. 2, a brushless motor 1 directly drives a rotation sensor 2 and a load 10 to rotate. As described in Japanese Patent Application No. 57-10691 filed by the present applicant, the brushless motor 1 includes a rotor having a multi-pole magnet (e.g. 8 poles) for a field, and a multi-phase coil ( The rotor includes a stator in which a rotor (for example, three phases) is arranged, and a position detection section including a plurality of position detection elements (for example, Hall elements) arranged in the stator to detect the rotational position of the rotor. In FIG. 2, a three-phase brushless motor 1 is used, and three-phase position detection signals hl, h2, . h3, and apply a three-phase drive signal (drive current) di to the three-phase coil.
, d2. d3 is supplied.

The rotation sensor 2 generates an alternating current signal a (waveform-shaped pulse signal) Zq times per rotation (Zq is an integer of 4 or more, and here Zq = 1024) as the brushless motor I rotates. do.

The AC signal a of the rotation sensor 2 is input to the speed detector 3,
A digital signal corresponding to the period of the AC signal a is obtained.

A specific example of the configuration of the speed detector 3 is shown in FIG.

AC signal a is passed through AND circuit 33 and flip-flop circuit 3
5 is entered. The clock pulse p of the oscillation circuit 32 and the overflow output signal W of the counter circuit 34 are also input to the input side of the AND circuit 33 . The oscillation circuit 32 is composed of a crystal oscillator, a frequency divider, and the like, and generates a clock pulse p (about 500 k) Iz) which has a considerably higher frequency than the frequency of the alternating current signal a. The counter circuit 34 is a 12-bit amplifier counter that counts up the contents every time the output pulse h of the AND circuit 33 arrives. Further, the overflow output signal W becomes ``HH'' when the count content of the counter circuit 34 is less than a predetermined value, and when the count content of the counter circuit 34 exceeds a predetermined value, W changes to "L" (here, ""H" represents a high potential state, "L" represents a low potential state)
. The data input type flip-flop circuit 35 uses the falling edge of the AC signal a as a trigger signal to take in "H" input to the data input terminal, and sets its output signal q to "H"(q="H"). ”). Further, when the reset signal r from the compensator 4 becomes "H", the internal states of the counter circuit 34 and the flip-flop circuit 35 are reset (b-"'LLLLLLLLLLLL", w="
H', q=”Lpa).

Next, the operation of the speed detector 3 shown in FIG. 3 will be explained.

It is now assumed that the counter circuit 34 and the flip-flop circuit 35 have been reset by the reset signal r. When the AC signal a of the rotation sensor 2 changes from "L" to "Ho", the output signal of the AND circuit 33 is output from the oscillation circuit 32.
A clock pulse p is output. The counter circuit 34 counts the output signals and changes its internal state. When the AC signal a changes from "H" to "L", the output signal of the AND circuit 33 becomes "L", and the counter circuit 3
4 holds its internal state. Further, the flip-flop circuit 35 takes in data "H" at the falling edge of the AC signal a, and changes its output signal q from °L to "H".
” change to.

The digital signal S of the counter circuit 34 has a value proportional to the (half) period length of the AC signal a of the rotation sensor 2, and is inversely proportional to the rotation speed of the brushless motor 1. A compensator 4, which will be described later, looks at the output signal q of the flip-flop circuit 35, and when q becomes "H", inputs the digital signal of the counter circuit 34, and then inputs the reset signal r for a predetermined short period of time. The counter circuit 34 and flip-flop circuit 35 are reset to the initial state in order to prepare for the next speed detection operation.When the rotation speed of the brushless motor 1 is too slow, the alternating current of the rotation sensor 2 is set to "H". Because the period of the signal a is long, the internal state of the counter circuit 34 exceeds a predetermined value, and the overflow output signal W changes from °°H'' to °゛L.
The output signal of the AND circuit 33 changes to °“L”.
, and the counter circuit 34 may hold a predetermined large value.

The compensator 4 in FIG. 2 is composed of an arithmetic unit 5, a memory 6, a D/A converter 7, and a rotational position detector 8. The compensator 4 in FIG. , outputs a control signal C. The control signal C of the compensator 4 is input to the driver 9, and the power is amplified as a three-phase drive signal dl.

d2. d3 (electronic signal IL obtained by proportionally amplifying the control signal C) is distributed and supplied to the three-phase stator coils according to the position detection signals hl, h2 and h3 of the brushless motor 1. It should be noted that a well-known circuit configuration as described in Japanese Patent Application No. 57-10691, for example, can be used for the driver 9.

Therefore, the brushless motor 1, the rotation sensor 2 (rotation sensor means), the speed detector 3 (speed detection means), and the compensator 4 (
A speed control system is constituted by the compensation means) and the driver 9 (driving means), and the rotational speed of the brushless motor 1 is controlled to a predetermined value. Note that the compensator 4 receives an operation command signal j from the operation command device 11, and is configured to perform a control operation according to the operation command signal j of the compensator 4. The operation command signal j is a digital signal of approximately 4 bits, and is a coded version of the operation command for the brushless motor 1.

For example, in the case of a capstan motor for a video tape recorder, in addition to the above-mentioned highly accurate speed control operation, the capstan motor performs operations such as a forward high-speed playback search and a reverse high-speed playback search.

These can be handled by changing the control operation details of the compensator 4.

The rotational position detector 8 of the compensator 4 receives two-phase detection signals h1. l! :h2 is input, and a digital signal i corresponding to the rotational position of the brushless motor 1 including determination of the rotational direction of the brushless motor 1 is obtained. FIG. 4 shows a specific example of the configuration of the rotational position detector 8. This will be explained with reference to the waveform diagram for explaining the operation in FIG. The position detection signals h1 and h2 are waveform-shaped by shaping circuits 41 and 42, respectively, to obtain shaped signals h1° and h2''.The physical arrangement of the detection elements is between the two-phase position detection signals h1 and h2. There is a phase difference (120 degrees electrically) between the shaped signals hl' and h2° as shown in FIGS. 5(a) and 5(b). A differential pulse e having a predetermined minute time width is generated at the edge and the falling edge (FIG. 5(C)).The shaped signals hl' and h2'' and the differential signal e are input to the direction discrimination circuit 44, and the shaped signal h1 The level of the shaped signal h2° at the arrival of the rising edge and falling edge of “H
” or L”), the rotational direction of the brushless motor 1 is detected, and a rotational direction detection signal g is obtained (Fig. 5(d)
)). That is, when the brushless motor 1 is rotating in the forward direction, the output signal g of the direction discrimination circuit 44 is H", and when the brushless motor 1 is rotating in the reverse direction, the output signal g of the direction discrimination circuit 44 is °L. ” becomes. The direction detection signal g of the direction determination circuit 44 and the differential signal e of the differentiator circuit 43 are sent to an up-down counter circuit 45 with a bit number (here, 3 bits) corresponding to the number of poles of the rotor magnet (8 poles in this example). input, direction detection signal g is “H”
When the direction detection signal g is "L", the counter circuit 45 counts up every time the falling edge of the differential signal e arrives, and when the direction detection signal g is "L", the counter circuit 45 counts up every time the falling edge of the differential signal e arrives. I'm counting down. Position detection signal ht of the position detection section of the brushless motor 1
The differential signal e obtained by shaping and differentiating is a pulse signal that occurs eight times during one rotation of the brushless motor l, corresponding to the number of poles (8) of the rotor magnet. Since the counter circuit 45 has 3 bits, its content, the digital signal i, takes values from O to 7, and its state number (8) is 1 of the brushless motor l.
It corresponds to the number of pulses during rotation. In addition, this number of states is a divisor of the number of times the speed detector 3 detects one rotation of the brushless motor 1 (Z (1=1024). In other words, the counter circuit 45 always detects the number of rotations of the brushless motor 1 during one rotation. The position is detected, a digital value corresponding to the rotational position of the brushless motor 1 is obtained, and the digital value is output as a digital signal i.

The memory 6 of the compensator 4 is divided into a ROM area (ROM: read-only memory) in which predetermined programs and constants are stored, and a RAM area (RAM: random access memory) in which necessary values are stored. The arithmetic unit 5 performs predetermined operations and calculations according to a program in the ROM area. 1st
The figure shows a specific example of the program. Next, the operation will be explained in detail.

[Rotation Error Calculation Unit IAI CIA-1] First, the arithmetic unit 5 inputs the output signal q of the flip-flop circuit 35 of the speed detector 3, and waits for the signal q to become "H". That is, speed detector 3
detects the (half) cycle of the AC signal a and monitors the output of a new detected digital signal.

(IA-2) When q becomes "H°", speed detector 3
reads the detection digital signal S and converts it to the speed detection digital value S corresponding to the detection digital signal S, and also sets the reset signal r to "H" for a predetermined period of time to activate the counter circuit 34 and flip-flop circuit 35 of the speed detector 3. Reset.

(IA-3) Subtract the speed detection digital value S from the predetermined reference value S ref to obtain a new digital speed error of the brushless motor 1 at the current time (E).

=Sref-3), and the speed error Eo is multiplied by R to calculate the new digital rotation error E of the brushless motor 1 at the present time (E=R-Eo).

[Control signal creation unit IB] (IB-1) Adds and synthesizes the current rotational error E and the memory output value Vo from the memory output value creation unit IDb of the memory value storage unit ID, which will be described later, at a predetermined ratio (1:D). and obtain the digital composite value Y (Y=E+D-Vo), where D
is a constant of 0.5 or more and 1.2 or less, preferably D=1
(IB-2) The digital composite value Y (control signal digital value) is output to the D/A converter 7 and converted into a DC voltage (control signal C) corresponding to the value of Y.

[Storage position detection unit ICI Stable state determination unit ICa> (ICa-1) The absolute value 1Eol of the digital speed error proportional to the detected digital value S of the speed detector is the predetermined value E
When it is larger than x (lEol≧Ex), it is determined that the state is unstable and transient, and the digital signal i of the rotational position detector 8 is input and the digital value corresponding to the digital signal i is determined.
d, assign Id to io (Io=Id), set VO corresponding to the memory output value to O (Vo=O), set the variable Ga for branch judgment to O (Ga=O), and then change the control operation. Moving on to the operation of section IE. At this time, the rotational position detection unit ICb
and the operation of the stored value storage unit ID is not executed. Further, when the absolute value IE01 of the speed error is smaller than the predetermined value Ex (lEo1<Ex), it is determined that the speed control state is stable, and the operation of the rotational position detection unit ICb is started.

<Rotational position detection section ICb> (ICb-1) When the branch judgment variable Ga is 1, the operation moves to the stored value storage section ID, and when Ga is not equal to 1, the operation moves on to the following operation (ICb-2).

(ICb-2) Digital signal i of rotational position detector 8
is input and set to a digital value 1d corresponding to the digital signal i.

(ICb-3) New rotational position detection digital value 1d
When is equal to the old digital value Io, the control operation changing unit IE operates. When Id is not equal to Io, the second count variable described below! A digital value 1d to 2
Substituting the integer value multiplied by d (12=Ad -1d), this digital value 2 and the predetermined digital value Ma are expressed as Nx, which will be described later.
The value obtained by adding -L as mod is the set digital value 1m [lm=12+Ma (mod NxL
)], the first count variable (described later) ■ Set 1 to 0 ■ 1 =
0), the branch judgment variable Ga is set to 1 (Ga=1), and the branch judgment variable Gb is set to O (Cb=0), and then the operation of the control operation change unit IE is started. Here, Ad is Zq (the number of detections by the speed detector 3 during one rotation of the brushless motor l) and Pd (position detection signal h during one rotation of the brushless motor 1).
1 (the number of pulses of the shaped/differentiated signal e) divided by an integer Q to be described later [Ad=Zq/(Q-Pd)]. As a result, when a new differential signal e is generated based on the position detection signal h and the digital signal i of the rotational position detector 8 changes, the digital value 1d corresponding to the rotational position of the brushless motor 1 is used as the count variable 2 is initialized, the count variable 11 is initialized to 0, the branch judgment variable Ga becomes 1, and from the time when a new speed detection digital value S is obtained, the memory value storage unit ID is The action begins to take place. In addition, as described later, the digital value I2 is set to a predetermined value Ma (here, Ma is 1 or more and N
xL or less) is added to the above setting digital value 1m
and the branch judgment variable cb are used to switch the operation in the stored value storage unit ID.

[Stored value storage unit ID] <Selection branch unit IDa> (IDa-1) Store and save the current digital rotation error E in the register F[Q-II] corresponding to the first count variable Il, which will be described later. F [Q-II Cor E).

Here, Q is an integer of 2 or more and is a divisor of Zq.

Here, Q=8. Since the count variable 11 is counted up every time the speed detector 3 performs a speed detection operation and takes a value between O and Q-1 (described later), the register F[1]
From F[Ql], continuous time-series values of the digital rotation error E are obtained.

(IDa-2) With Q as mod, the first count variable 1 is counted up every time a new speed detection digital value S is obtained. That is, +1=+1+1 (
After setting [1+1 to new 11], if 11=Q, reset 11 to O. If such an operation is performed, 11 becomes an integer between 0 and Q-1. Note that the initial value of the first count variable 11 when starting the operation of the storage value storage unit ID is 0.

(IDa-3) If If is not 0, the operation moves to the control operation change unit IE. If 11 is 0, the process moves to the next operation of the memory output value creation unit IDb. As a result, the memory output value creation section IDb, the synthesis error creation section IDc, and the update storage section ID
d is a memory output value creation unit IDb> (IDb-1) Nx-L (here, L is (Zq/Q
), where Nx is an integer greater than or equal to 1), mod (
modulus), each time the first count variable 11 becomes 0, (
Every time Q new speed detection digital values S are obtained, the second count variable 2 is counted up. That is,
After setting +2=12+1, if +2-NxL, reset I2 to O. If we perform such an operation, I2
is an integer between 0 and NxL-1. Note that the second count variable 1 when starting the operation of the memory value storage unit ID
The initial value 2 is a value corresponding to the digital signal i immediately after the rotational position detector 8 changes, and is a value corresponding to the rotational position of the brushless motor 1.

(IDb-2) Substitute the second count variable 12 for the integer J (J = 12), and set N at intervals of L in the ram area.
x digital storage value group M [J-nL (mod
NxL)] (n=1.- ・+.

Nx), the memory output value Vo is calculated by the following equation.

Vo-Σ Wn-M [J-nL (mod NxL
]・・・・・・(I1 Here, the value of the ratio Wn is 0<Wn<2/Nx (n=1. . . . , Nx)−
=(2)Σ Wn=1 ・
...(3) shall be satisfied. Specifically, Wn= 1/Nx (n=1.2...., N
x) ...... (4), one division (or bit shift) after adding the predetermined digital storage value
By performing the following, calculation (1) 2 can be easily realized.

<Synthetic error creation unit IDc> (IDc-1) Rotation error time series F [m] obtained in the above-mentioned register F [m] (m=,0,1.
..., Fd) respectively have a predetermined positive ratio Bm (m=
1.2. ..., Fd) are added and synthesized to create a synthesis error Eg. That is, Eg-Σ Bm
-F [m]...-45) m+turbidity Here, there is a relationship between the coefficient Bm. Furthermore, Σ Bm=1...
- Standardized as (7).

(IDc-2) Transfer the contents of register F[m] to register F[Q+m (m=1.2....
, Q). As a result, at the time of calculating the next composite error Eg, 2Q registers F [m] (m-1, 2, ·
..., 2Q), a continuous time-series signal of rotation error E is obtained. Note that 2Q≧Fd (register F
(The number of [m] can also be increased).

Update storage section I Dd> (IDd-1) When the branch judgment variable Gb is 1,
Moving on to the operation of (IDd-2). When Gb is other than 1 (
When Gb=0), the second count variable 12 and the aforementioned set digital value 1m are compared, and when 12=Im, Gb is set to 1 (Gb=1), and the operation of the control operation changing unit IE is started. As a result, the following operation to update and save the stored value (IDd-2) is performed after the second count variable 12 becomes equal to the set digital value 1m.

(IDd-2) Calculate the update value by calculating the synthesis error Eg and the memory output value Vo of the memory output value creation unit IDb at a ratio of 1:1, and calculate the update value in the RAM area corresponding to the second count variable ■2. Update the digital memory value M[+2] in M
[12] =Eg+Vo), stored and saved until the next update. After that, the process moves to the operation of the control 4U operation changing unit IE.

[Control operation change unit IB] (IE-1> Operation command signal of operation command device 11) is manually input.

(IE-2) The operation command signal j is read, and when it is a speed control command, the rotation error calculation unit IA returns to operation. When an operation command other than a speed control command is issued (for example, a high-speed regeneration search in the forward direction or a high-speed regeneration search in the reverse direction), the operation command signal j is changed while causing the brushless motor 1 to perform an operation according to the command. is checked, and when the speed control command is issued again, the operation shifts to the rotation error calculation unit IA.

Here, since the actual operation content other than the speed control operation is not the gist of the present invention, a detailed explanation thereof will be omitted.

With this configuration, when controlling the speed of the brushless motor 1, it becomes extremely resistant to fluctuations in the load torque generated by the load 10 shown in FIG.

This will be briefly explained. Since the rotation error and the memory output value are added to create a new digital storage value, the above NxL digital storage values M [1] (1-0, 1, .
. . , NxL-1), a pattern corresponding to the time change of the rotation error is formed.

The pattern held by these digital stored values is reflected in the memory output value Vo. In the control signal generation unit IB,
Since the control signal is created by the summation value Y of the rotation error E and the memory output value ■0, the rotation error side will be smaller for the pattern created by the memory output value vO after the control operation for the required time (in some cases, It may be zero). A small rotational error E means that the speed fluctuation of the brushless motor 1 itself is small, and an extremely good effect is obtained. In particular, such an effect can be obtained in a specific frequency group corresponding to the update cycle of NxL digital stored values. In this embodiment, the update cycle of the digital stored values is set to It is an integral multiple of one rotation period.

Furthermore, in this embodiment, immediately after the speed detector 3 obtains a new detection digital signal, the rotation error calculation section IA and the control signal generation section IB are made to operate with priority over the operation of the stored value storage section ID. I have to. In particular, since the memory output value creation unit IDb of the memory value storage unit ID roughly calculates the memory output value Vo to be used at the time of the next speed detection, a new detection digital signal can be obtained and then used for new control. The time delay until signal Y is obtained is extremely short. This time delay is very important in control, and the shorter the time delay, the larger the control gain can be, and the smaller speed fluctuations due to load fluctuations. That is, the speed fluctuation in this example is small.

Further, as shown in this embodiment, the control signal generation unit IB generates a new control signal every time the speed detector 3 obtains a new detection digital signal, and the speed detector 3 generates a new detection digital signal Memory value storage section I
If D is configured to update one digital storage value, the number of memories required for storing the digital storage value of the storage value storage unit ID will be reduced to one-ninth.1For example, ZQ=102
4°Q-8, L=Zq/Q=128. If Nx=2, the number of required memories is 256.

Furthermore, as shown in this embodiment, Pd continuous rotational errors are combined to obtain a combined error Eg, and a digital storage value M[
It has been found that by updating [I2], it is possible to prevent the operation from becoming unstable due to unnecessary noise components included in the rotation error E. This is because it is possible to prevent the influence of fairly high-frequency fluctuations included in the rotational error from entering the digital stored value or memory output value. Further, even if the synthetic error creation section was inserted before the update storage section, there was almost no adverse effect on the speed fluctuation improvement effect described above.

Furthermore, in this embodiment, even when the compensator 4 is performing operations other than speed control of the brushless motor 1 according to instructions from the operation command device 11, a plurality of digital stored values M[ I2] (+2=0.1. ・-+,
NxL-1) is held, and the rotational position of the brushless motor 1 is constantly detected by the rotational position detector 8.

Therefore, during the subsequent speed control operation, when the digital speed error of the brushless motor 1 falls within a predetermined small range, the digital signal i (digital value 1d) of the rotational position detector 8 is used to control the brushless motor l. The storage position (value of the second count variable I2) of the digital storage value of the storage value storage unit ID corresponding to the rotational position can be detected, and the update storage operation can be performed sequentially from that storage position.

Furthermore, the control signal generation unit IB can quickly utilize the digital storage value information held in the update storage unit IDd of the storage value storage unit ID in correspondence with the rotational position of the brushless motor 1. The effect of reducing fluctuations can be obtained. In particular, the digital signal i of the rotational position detector 8 responsive to the position detection signal h1 is in 8 states (0 and 0) during one rotation.
to 7), the signal i immediately after the digital signal i of the rotational position detector 8 changes.
Since the rotational position of the brushless motor 1 is detected using the value of , the accuracy of rotational position detection is high regarding the value of the second count value I2 corresponding to the digital signal i (digital value 1d) at the time of the change. The position of the digital stored value (count value I2) corresponding to the rotational position of the brushless motor 1 is detected accurately or almost accurately. Furthermore, if the two-phase position detection signals h1 and h2 of the position detection unit, which is a component of the brushless motor 1, are used, there is no need to provide special sensor parts for rotational position detection (there are fewer components, good.

In the above embodiment, the number of states of the rotational position detector 8 during one rotation is Pd=8. The number of detections per rotation of the speed detector 3 is Zq=1024. As an integer Q=8, Pd is Zq/
Although Q is a divisor of 128, the present invention is not limited to such a case, and the relationship can be set arbitrarily. In general, the position of the digital storage value corresponding to each value of the digital signal i of the rotational position detector 8 (at least the second count value + 2, preferably the first count value 11 and the second count value + 2) is set respectively. By storing it in memory, the position of the digital stored value corresponding to the rotational position (digital value 1d) of the brushless motor 1 can be easily found.

Furthermore, as in this embodiment, by using the branch judgment variable cb and the set digital value 1m, at the time of transition to speed control operation,
First, the memory value storage unit ID is not updated and saved (the memory output value creation operation is performed), and the control operation using the rotation error calculation unit IA and the control signal creation unit IB is performed. Then, after an appropriate time period corresponding to the predetermined value Ma has elapsed, the stored value storage section ID is updated and stored, and the rotation error calculation section IA, the stored value storage section ID, and the control signal generation section IB are used. By configuring the system to shift to control operation, the effects of spike-like speed fluctuations at the moment of shift to control using the stored value M [1] are quickly converged. This will be further explained. When control is shifted to using the stored value M [1], pulsations equal to the stored value will be input to the control signal Y.

Due to this pulsation, a phenomenon occurred in which the speed of the brushless smoke 1 fluctuated slightly significantly immediately after the transition.

Therefore, if you update and save the memory value M [+] at the same time as the transition, the effect of sudden speed fluctuations immediately after the transition will be affected by the memory value M
[1], and after a vague update operation, it is output as the memory output value Vo to the control signal Y, causing the speed of the brushless motor 1 to pulsate again.

Although this pulsation will eventually disappear after a long period of time, it is preferable to eliminate it from the viewpoint of quickly reducing the speed fluctuation of the brushless motor l. Therefore, in this embodiment, updating and saving of the memory value is stopped for the required time immediately after shifting to control using the memory value M [1] (the control signal of the memory output value corresponding to the memory value is ). As a result, it was confirmed that the speed fluctuation of the brushless motor 1 described above was quickly reduced.

Moreover, thereby, the time-series signal F [m] for calculating the synthesis error Eg can also be easily prepared.

FIG. 6 shows an example of a program for the compensator 4 in consideration of the stability of the entire control system. Here, we have improved the method of calculating update values in the update storage section, the number of memory output values prepared in the memory output value creation section, and the method of using memory output values of the memory output value creation section in the control signal creation section. are doing. Next, its operation will be explained in detail (the overall configuration is the same as that in FIG. 2, so the explanation will be omitted).

[Rotation error calculation unit 6A] (6A-1) First, the arithmetic unit 5 inputs the output signal q of the flip-flop circuit 35 of the speed detector 3, and waits for the signal q to become °゛H°°. . That is, the speed detector 3 detects a (half) cycle of the AC signal a and monitors the output of a new detected digital signal.

(6A-2) When q becomes °゛H'', read the detection digital signal of the speed detector 3, change it to the speed detection digital value S corresponding to the detection digital signal S, and keep the reset signal r for a predetermined period of time. Ho'' to reset the counter circuit 34 and flip-flop circuit 35 of the speed detector 3.

(6A-3) Subtract the speed detection digital value S from the predetermined reference value 5 ref to obtain the new digital speed error of the motor 1 at the current moment (E o = S ref - S
).

The speed error EO is multiplied by R to calculate a new digital rotation error E of the motor 1 at the present time (E=R·Eo).

[Control Signal Creation Unit 6B] (6B-1) Adds the current rotation error E and a new memory output value Vo from the memory output value creation unit 6Db of the memory value storage unit 6D, which will be described later, at a predetermined ratio (1:D). and obtain a digital composite value Y (Y=E'+D −V o
), where D is a constant of 0.5 or more and 1.2 or less,
Preferably D=1° (6B-2) Digital composite value Y
(control signal digital value) is output to the D/A converter 7, and Y
is converted into a DC voltage (control signal C) corresponding to the value of .

[Memory position detection unit 6C] <Stable state determination unit 6Ca> (6Ca-1) The absolute value IE01 of the digital speed error proportional to the detected digital value S of the speed detector is a predetermined value E.
When it is larger than x (lEol≧Ex), it is determined that it is an unstable transient state, and the digital signal i of the rotational position detector 8 is inputted to obtain the digital value 1 corresponding to the digital signal i.
d, substitute Id for Io (Io=Id), VO and V corresponding to the memory output value [Set Pxl to 0, Vo=0
After setting the variable Ga for branch judgment to 0 (Ga=0), the process moves to the operation of the control operation changing unit 6E.

At this time, the operations of the rotational position detection section 6Cb and the stored value storage section 6D are not executed. Also, the absolute value of the speed error is 1Eol
When is smaller than the predetermined value Ex, (l
Eo l<Ex), it is determined that the speed control state is stable, and the operation moves to the rotational position detection section 6Cb.

<Rotational position detection section 6Cb> (6Cb-1) When the branch judgment variable Ga is 1, the operation moves to the stored value storage section 6D, and when Ga is not equal to 1, the operation moves on to the following operation (6Cb-2).

(6Cb-2) Input the digital value i of the rotational position detector 8 and set it to the digital value Id corresponding to the digital signal i.

(6Cb-3) New rotational position detection digital value 1d
When G is equal to the old digital value 1o, the control operation changing section 6E moves to operation. When Id is not equal to IO, a digital (il
Substituting the value obtained by multiplying d by Ad (T2=Ad・Td), this digital value I2 and a predetermined digital value Ma are expressed as Nx-
The setting digital value obtained by adding L as mod is 1m.
and None [lm=12+Ma (mod NxL)],
First count variable (described later) Set 1 to 0 + 1 = 0),
After setting the branch judgment variable Ga to 1 (Ga=1) and setting the branch judgment variable Gb to O (Gb=O), the process moves to the operation of the City II control operation changing unit 6E. Here, Ad&YoZq (the number of detections by the speed detector 3 during one rotation of the brushless motor 1) is expressed as Pd (the position detection signal h during one rotation of the brushless motor 1).
1 (the number of pulses of the shaped/differentiated signal e) divided by the integer Q described later [Ad=Zq/(Q-Pd)]. As a result, when a new differential signal e is generated by the position detection signal hl and the digital signal i of the rotational position detector 8 changes, the count variable 12 is initialized, the count variable 11 is initialized to 0, the branch judgment variable Ga becomes 1, and from the time when a new speed detection digital value S is obtained, the stored value storage unit 6
Operation D is now performed. In addition, as will be described later, the stored value storage unit Switching the operation in 6D.

[Memory value storage section 6D] Select branch section 6Da> (6D a -1) Stores and saves the current digital rotation error E in the register F[Q-■1] corresponding to the first count value ■1, which will be described later. (F [Q-11]=E
). Here, Q is an integer of 3 or more, and here Q=8
It is. Since the count value 11 is counted every time the speed detector 3 performs a speed detection operation and takes a value between 0 and Q-1 (described later), the registers F[1] to F[Ql contain the digital rotation error E. Continuous time series values are obtained.

(6Da-2) With Q as mod, the first count variable ■1 is set every time a new speed detection digital value S is obtained.
Count and amp. That is, 11=11+1
After setting (11+1 to new If), +1=
If it is Q, ■ reset 1 to O. If such an operation is performed, If will be an integer between 0 and Q-1. Incidentally, the initial value of the first count variable (1) when starting the operation of the stored value storage section 6D is O.

(6Da-3) When 11 is equal to Ql (here, Ql is an integer smaller than Q), the memory output value Vo is
[Px], and if 11 is not equal to Ql, such a changing operation is not performed. As a result, If<Ql
In the range of , Vo=V[Px-1ko (described later), and 1
In the range of 1≧Ql, Vo=V [Px].

(60a-4) When 11 is equal to Q-1, the operation moves to the memory output value creation section 6Db.

(2) When 1 is equal to O, the operation moves to the composite error creation section 6Dc. (2) When 1 is equal to 1, the operation moves to the update storage section 6Dd. When 11 is other than these values, the process shifts to the operation of the control operation changing section 6E.

As a result, the memory output value creation section 6Db, the composite error creation section 6Dc, and the update storage section 6Dd are executed once every Q times of detection operations of the speed detector 3.

<Memory output value creation unit 6Db> (6Db-1) With Nx −L as mod,
Every time the first count variable 11 becomes O (every time a new speed detection digital value S is obtained Q@), the second count variable 1
Count up 2.

The initial value of the second count variable 2 when starting the operation of the memory value storage section 6D is the value corresponding to the digital signal i immediately after the change in the rotational position detector 8, and is the value corresponding to the digital signal i immediately after the rotational position detector 8 changes. The value corresponds to the rotation position.

(6Db-2) Calculate the integer J by adding Px (here, Px is an integer greater than or equal to 1 and less than or equal to 3, and preferably Px = 1) to the second count variable 12 with NxL as mod [J = I2+Px(mad NxL)].

(6Db-3) After sequentially transferring the contents of register variable V[m+13 to V[ml (m=0゜1,...
, Px-1), a group of Nx digital storage values M[J-nL (mod NxL)] separated by L intervals in the RAM area
Put the latest memory output value calculated by the following formula using (n=1.---, Nx) into V[Pxl.

V[Px co-ΣWn-M[J
-nL (mod NxL)]・・・・・・(8
) Here, the value of W n is expressed as (2), (3) and (4)
satisfies the formula. That is, from V [Pxl to V [
0] to obtain a group of Px+1 consecutive memory output values. At this time, the integer J in equation (8) when calculating V[Pxl
Let Jl be Jl, and let J2 be the integer J in equation (8) when calculating 10], then there is a relationship of J1=J2+Px. Next, the memory output value ■0 used first in the control signal generation unit 4B is set to V [Px-1] (V o =
V [P x 1 ] )a After that, the process moves to the operation of the control operation changing section 6E.

<Synthetic error creation unit 6Dc> (6Dc-1) Registration value F[mco (m=0.1. . . .) storing the rotation error time series described above.

Fd) with a predetermined positive ratio Bm (m=1°2, ・
..., Fd) are added and synthesized, and the synthesis error Eg
[Equations (5), (6), (7).

(6Dc-2) Transfer the contents of register F [ml to register F [Q+m] (m=1.2°..., Q
), as a result, at the time of calculating the next composite error Eg, 2Q registers F [ml (m=1.2...
, 2Q), a continuous time-series signal of rotation error E is obtained. Note that 2Q≧Fd. After that, the operation of the control operation changing section 6E is repeated.

Update storage section 6Dd> (6Dd-1) Calculate the integer K by subtracting Kd from the second count variable ■2 with NxL as mod [K=1
2-Kd (mod NxL)].

(]6Dd-2 After transferring the contents of register variable X[m+1 to X[ml in order) (m=0゜1.2.・
..., 2Kd-1), Input the composite value calculated and synthesized at the ratio of Egt1:l (X [2Kd] = Eg10V [0]). That is, 2Kd consecutive from X[2Kd] to X[0]
+1 additional value (addition value of memory output value and synthesis error) is obtained.

(6Dd-3) When the branch judgment variable cb is 1,
Moving on to the operation (6Dd-4). When Gb is other than 1 (
C; when b = 0), compare the second count variable 12 and the aforementioned set digital value 1m, and when 12 = Im, Gb is set to 1.
(G b = 1), the process moves to the operation of the control operation changing section 6E. As a result, the following storage value update/save operation (6Dd-4) is performed after the second count variable 12 becomes equal to 1m.

(6Da-4) X [predetermined positive ratio Cm to ml
Obtain a new updated value by adding and combining the values multiplied by (m=0.1. . . . , 2Kd), update the digital storage value M [K] in the RAM area corresponding to the integer K, and then Stored until updated. That is, M [K] = Σ Cm
−X Cm] −=・(9). Here, the ratio Cm has the following relationship.

C,, ==02, -, (m=o, 1.---, Kd
)・・・・・・00 Σ Cm=1 ・・・・・・(
11) After that, the process moves to the operation of the control operation changing section 6E.

As a result, when the branch judgment variable Gb is 1, NxL
digital memory values M[K] (K=0.1°...
, NxL-1) are updated and saved one by one every time the speed detector obtains Q new detection digital signals.

[Control operation change unit 6E] (6E-1) Inputs the operation command signal j of the operation command device 11.

(6E-2) Read the operation command signal j, and when it is a speed control command, return to the operation of the rotation error calculation section 6A. When an operation command other than a speed control command is issued (for example, a forward high-speed regeneration search or a reverse high-speed regeneration search operation), the change in the operation command signal j is controlled while causing the motor 1 to perform the operation corresponding to the command. When the rotation error calculation unit 6A changes and becomes a speed control command again, the rotation error calculation unit 6A shifts to operation. here,
Since the actual operation content other than the speed control operation is not the gist of the present invention, a detailed explanation thereof will be omitted.

As in this embodiment, the update storage section 6. The first memory output value V of the memory output value creation unit 6Db used in the control signal creation unit 6B by inserting a calculation to take a weighted average into Dd.
o (V [Px]) and the second memory output value v of the memory output value creation unit 6Db used in the update storage 6Dd
It was confirmed that if a predetermined deviation (V[Px] is ahead of ■[0]) is provided between [0], the operation of the entire control system becomes stable.

Further, in this embodiment, the timings of the operation of the memory output value creation section 6Db, the operation of the composite error creation section 6Dc, and the operation of the update storage section 6Dd of the stored value storage section 6D are shifted with respect to the detection operation of the speed detector 3. . As a result, the amount of calculation required within one detection cycle of the speed detector 3 is significantly reduced, and it is also possible to use a microcomputer with a slow operating speed for the arithmetic unit 5 of the compensator 4. becomes. In particular, as shown in this embodiment, the operation of the memory output value creation section 6Db, the operation of the synthesis error creation section 6Dc, and the update storage section 6Dd
When the operation includes a large number of transfers and multiplications, the effect of reducing the amount of calculation required within one detection period of the speed detector 3 is significant, which is a great practical advantage.

In addition, the update storage operation of the update storage section 6Dd [(6Dd-4
)] is not performed (Gb=O), the register variable X [m] is prepared, so when the update save operation is performed, the
[m] can be used to immediately calculate the updated value.

It should be noted that calculations using the ratios Wn and Cm are not limited to the above-mentioned forms, but may be any form that realizes the contents of the above-mentioned program, and it goes without saying that various equivalent expression transformations are possible. In addition, when a new rotation error is obtained, the control signal generation section first outputs a new control signal, and then the memory output value generation section of the memory value storage section outputs the memory to be used at the next sampling point. If the value is calculated, the calculation time of the memory output value generation section can be lengthened, and the time delay until the control signal is output can be shortened, making it easier to ensure the stability of the control system.

In each of the above-mentioned embodiments, only the rotational speed of the brushless motor is detected by the speed detector, but in addition to this, the rotational phase of the brushless motor is detected by a well-known phase detector, and both are combined to create a digital signal. It goes without saying that this may be considered a rotation error and is included in the present invention. Further, the output of the compensator may be a digital signal or a PWM signal (pulse width modulation signal), or the output signal of the driver may be a PWM signal. Further, the configuration of the brushless motor is not limited to the above-described embodiment, and various known brushless motors having a position detection section that detects the rotational position of the rotor can be used.

Furthermore, the compensator can be configured completely in hardware,
The same operations as those performed by the program described above may be performed. In addition, various modifications can be made without changing the gist of the present invention.

Effects of the Invention The brushless motor control device of the present invention can perform high-performance speed control with a small number of memories, and can significantly reduce rotational speed fluctuations in a short time when transitioning to speed control operation. Therefore, if the capstan motor of a video tape recorder is configured according to the present invention, the running speed of the magnetic tape can be controlled extremely accurately, and a high performance video tape recorder with less wow and flutter can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing an example of a built-in program of a compensator of a control device for a brushless motor according to an embodiment of the present invention, FIG. 2 is a block diagram showing the overall structure of the embodiment of the present invention, and FIG. is a block diagram showing a specific example of the configuration of the speed detector in FIG. 2, FIG. 4 is a block diagram showing a specific example of the configuration of the rotational position detector in FIG. 2, and FIG. FIG. 6 is a waveform diagram for explaining the operation of the rotational position detector, and FIG. 6 is a flowchart diagram representing an example of a built-in program of a compensator of a control device for a brushless motor representing another embodiment of the present invention. 1... Brushless motor, 2... Rotation sensor, 3... Speed detector, 4... Compensator, 5... Arithmetic unit , 6... Memory,
7...D/A converter, 8...Rotational position detector, 9...Driver, 10...Load, 11...・Operation command device.

Claims (3)

[Claims] (1) a brushless motor having a position detection section that detects the rotational position of the rotor; and rotation sensor means that generates an alternating current signal with a period corresponding to the rotational speed of the brushless motor;
speed detection means for detecting a plurality of times per rotation of the brushless motor based on the alternating current signal of the rotation sensor means; a compensation means for generating a control signal; and a drive for driving the brushless motor in accordance with the control signal of the compensation means. and operation command means for instructing the operation content of the compensation means, and the compensation means calculates a rotation error by obtaining a digital rotation error from the detection digital signal of the speed detection means for each detection operation of the speed detection means. means for generating a digital composite error by combining at least two digital rotation errors of the rotation error calculating means; and Q times (where Q is an integer of 2 or more) of the speed detecting means. an update storage means for updating and storing one of the plurality of digital storage values in order for each detection operation with a value corresponding to the digital synthesis error and a composite value of at least one of the digital storage values; and the digital rotation. control signal generating means for generating the control signal by synthesizing the error and at least one of the digital stored values; and obtaining a digital value corresponding to the rotational position of the brushless motor based on the output signal of the position detection section of the brushless motor. It has a rotational position detecting means and a control operation changing means for changing the content of the control operation according to an instruction from the operation commanding means, and when the instruction from the operation commanding means becomes a speed control operation, the digital value of the rotational position detecting means is changed. A control device for a brushless motor, wherein a storage position of a digital storage value of the update storage means corresponding to a rotational position of the brushless motor is detected using the digital storage means, and an update storage operation of the update storage means is performed from the storage position. (2) A control device for a brushless motor according to claim (1), wherein a time point at which the digital value of the rotational position detecting means changes is detected, and a storage position corresponding to the digital value at the time of the change is obtained. (3) When transitioning to speed control operation based on instructions from the operation command means, first, the update storage means is not operated and a control operation is performed using the rotation error calculation means and the control signal generation means, and then, 2. A control device for a brushless motor according to claim 1, wherein said update storage means is also operated after a required time has elapsed.