JP2895355B2 - Drive circuit for brushless motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sensorless brushless motor drive circuit.

[0002]

2. Description of the Related Art A sensorless brushless motor in which a rotational position of a rotor is detected by detecting a back electromotive force of a drive coil and energization of the drive coil is controlled in accordance with the detection signal does not require a sensor. There are various advantages based on this. However, once stopped, back electromotive force is not obtained, and at the time of startup, the rotor needs to be largely moved when performing the position detection operation of the rotor, that is, the initial setting operation. Thus, when the motor and the load are directly connected and it is not necessary to operate the motor during the rotor position detection operation, the motor cannot be used.

Accordingly, the applicant has made the encoder output a rotation signal in accordance with the rotation of the rotor, and based on the output of the encoder, detects that the rotor has rotated by a predetermined amount or more by over-rotation detecting means. A drive circuit for a brushless motor which detects a position at which the rotor starts to rotate by a predetermined amount or more based on the output and calculates an initial position of the rotor from the detected position has been previously applied for a patent (Japanese Patent Publication No. 2-290188). Gazette). According to the invention of this application, when calculating the initial position of the rotor, the rotor only needs to be rotated to output a few pulses at the output level of the encoder, which is equivalent to almost no movement. Therefore, the present invention can be applied to, for example, a robot or a machine tool in which a motor must not move during a rotor position detection operation.

[0004]

As described above, the invention according to the above-mentioned application has excellent effects, but there is still room for improvement. That is, the invention according to the above-mentioned application is shown in FIG.
As shown in FIG. 3, the initial position of the rotor (specifically, the initial position of the magnetic pole) is estimated by calculation by detecting a point a where the generated torque Tg (θd) becomes 0, and this is set as the initial position. Is what you do. However, if the disturbance torque Tl is applied to the motor during the initial position setting operation, there is a problem that an accurate initial position cannot be detected. The reason is specifically described as follows.

Now, as shown in FIG.
Suppose that 1 was Tl = 3 / 2.Tref'.beta.Kt / 2. Tref 'is the torque command Tref
Is set to a range where the motor does not burn out. Originally, the point a in FIG.
_Although it must be detected as ₀ , the point b deviated from the initial position θ _{0 due} to the application of the disturbance torque Tl is detected. Therefore, the error θer of the initial position θ ₀ is as shown in Expression 1.

(Equation 1)

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art. In a brushless motor having no means for detecting the magnetic poles of a rotor, even if disturbance torque is applied during an initial setting operation, the present invention has been made. It is an object of the present invention to provide a drive circuit capable of detecting an accurate initial position.

[0007]

Means for Solving the Problems The present invention, in advance row
The first rotor initial position estimate obtained by the calculation Tsu in (.theta.o), a second rotor which is obtained by adding an arbitrary value ([Delta] [theta])
There line current control by using the initial position estimate (.theta.1), position
Torque command (Tref) in a stopped state after performing control
p) and a third rotation obtained by subtracting an arbitrary value (Δθ)
There line current control by using child initial position estimate with (.theta.2), position
Torque command under the stopped state after the location control (Tre
fn), and trying a plurality of arbitrary values, | T
Search for any value that minimizes refp-Trefn |
And adds it to the first rotor initial position estimated value (θo).
And a correction means for setting a correction value .

[0008]

Since the initial position of the rotor before the power is turned on is indefinite, there is no correspondence between the excitation current pattern at the time of turning on the power and the rotor position, and the rotor cannot rotate . The energizing means is sequentially controlled by the logic operation means and the exciting current is sequentially controlled, and the rotor starts to rotate soon. When the rotor rotates by a predetermined amount or more, the over-rotation means detects this . The logic operation means detects a position at which the rotor starts to rotate by a predetermined amount or more based on a detection output from the over-rotation detection means, and calculates an initial position of the rotor from the detected position. The correction means is based on an operation performed in advance.
The first rotor initial position estimated value (θo) obtained by
Estimation of initial position of second rotor to which arbitrary value (Δθ) is added
There line current control by using the value (θ 1), subjected to position control
The torque command (Trefp) in the stop state after the stop
And the third rotor initial position obtained by subtracting an arbitrary value (Δθ)
There line current control by using the estimated value (.theta.2), the row position control
The torque command (Trefn) in the stopped state
| Trefp−
Search for an arbitrary value that minimizes Trefn |
The correction value is added to the estimated rotor initial position value (θo) .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a brushless motor driving circuit according to the present invention will be described below, but before that, an outline of the present invention will be described. Since the initial position θ ₀ of the rotor before the power is turned on is indefinite, the energization pattern of the excitation current to the drive coil and the rotor position θf deviate from a predetermined correspondence. When the coil is energized in this state, the position command is 0 in the initial state and a position control loop for stopping is applied, so that the rotor cannot rotate. Strictly speaking, the rotor repeatedly rotates by a small angle alternately in the forward direction and the reverse direction, but in the present invention, this state is defined as “stop”.

When the pattern of the excitation current supplied to the drive coil is changed by changing the command signal θc for determining the excitation current pattern, the transfer function from the current command to the torque output of the position control loop changes, and when a certain point is reached. The position control loop becomes a positive feedback, that is, oscillates, and the motor runs out of control without effective position control. In the present invention, this state is defined as "rotation" in the sense that the state has been rotated by a certain amount or more.

In the present invention, θc is changed to detect θc at the point where the position control loop changes from negative feedback to positive feedback, and if that point is θd, then θd = 90 ° and θd = 90 °.
From the relationship θc−θf, an initial rotor position θ ₀ is determined. If the initial position θ _{0 of the} rotor is determined, the command signal θc for determining the excitation current pattern can be set to θc = θf, and the motor can be freely rotated by sequentially changing the command signal θc.

In FIG. 1, the rotor denoted by reference numeral 1 is illustrated as being constituted by a permanent magnet having a pair of magnetic poles of NS for simplification of description. The stator has a three-pole configuration of 2u, 2v, and 2w, and drive coils 3u, 3v, and 3w are wound around each stator.
Each drive coil 3u, 3 v, amplifier A _1, A _2, A ₃ through excitation currents Iu as energizing means for 3w, Iv, Iw
Are turned on, thereby generating a rotating magnetic field in the stators 2u, 2v, 2w.

An encoder E is connected to the rotor 1, and the encoder E outputs a two-phase pulse-like rotation signal whose phase is shifted by, for example, 90 ° according to the rotation of the rotor 1.
Here, in order to simplify the description, it is assumed that the resolution of the encoder E is 360 RPM, that is, one pulse is output for a rotation angle of 1 °. The rotation signal output from the encoder E is input to the up-down counter C _1, is input located at the detection means C ₂ and the speed detector Sd composed of up-down counter. Position detection means C ₂ detects the rotational position of the rotor by the rotation signal. The output e of the position detecting means C ₂ is input to the position control unit 5 as a position feedback signal, a position command signal d
Is determined. Position command signal d is, when the first switching means SW ₁ selects the contact position command Pref
, And the is the initial setting position command Pref ₀ when (= 0) when the switching means SW ₁ selects the contact point. The output e of the position detecting means C ₂ is also inputted to the over rotation detector F. The over-rotation detecting means F detects from the output e whether or not the rotor has rotated by a predetermined amount or more, and the detected output f is input to a _second logical operation means B2 comprising a central processing unit (CPU). .

The second logical operation means B ₂ detects the position at which the rotor 1 rotates by a predetermined amount or more based on the output f from the over-rotation detecting means F, and determines the initial position of the rotor 1 from the detected position. Calculate θ ₀ . The second logical operation means B ₂ sets the initial value of the counter C _{1 based on} the calculated initial position θ ₀ and inputs a reset signal g to the position detection means C ₂ . The second logical operation means B ₂ exchanges data with the first logic operation means B _1. The first logical operation means B ₁ sequentially controls the amplifiers A ₁ , A ₂ , A ₃ as the energizing means to control the drive coil 3.
u, 3v, 3w for controlling the exciting current,
A command signal θc ₂ for determining the excitation current pattern is output. The command signal θc ₂ is stored in the memory R as the command signal θc when the second switching means SW ₂ selects a contact.
₁ , R ₂ and R ₃ are input. When the second switching means SW ₂ is selected contact, inputs a count signal .theta.c ₁ by the counter C ₁ in the memory R _1, R _2, R ₃ as a command signal .theta.c. The memories R ₁ , R ₂ , R ₃ store the driving coils 3u, 3
Excitation current waveforms for energizing v and 3w are stored as data, and the data is as shown in Equation 2.

(Equation 2) The outputs a, b and c of each memory are converted into analog signals by digital / analog converters D ₂ , D ₃ and D ₄ .

[0015] After the deviation signal between the output e and the position command signal d of the position detecting means C ₂ obtained by the position control means 5 is converted into an analog signal by a digital-to-analog converter D _1, position deviation amplifier Com Amplified by _one . The output of the position deviation amplifier Com ₁ is further supplied to the speed deviation detecting means 6.
Thus, a deviation from the speed signal from the speed detector Sd is obtained. This deviation signal is amplified by the speed deviation amplifier Com _2, three multipliers M _1, M as the torque command Tref
Is input to the _2, M _3. In each of the multipliers M ₁ , M ₂ , and M ₃ , the torque command Tref and the digital / analog converter D ₂ ,
The quotients of the outputs a, b, and c of the memories converted into analog signals by D ₃ and D ₄ are obtained, and the amplifiers A
₁ , A ₂ and A ₃ are input. First switching control of the switching means SW ₁ is performed by a second logical operation means B _2, the second switching control of the switching means SW ₁ is performed by the first logical operation means B _1.

A torque command Tref output from the speed deviation amplifier Com is input to an analog / digital converter G via a low-pass filter H, and a digital signal Tref
Is converted to Output T of analog-to-digital converter G
ref is input to the second logical operation means B 1. The second logical operation means B has a correction means for correcting a deviation of the initial position detection due to a disturbance torque applied to the motor. This correction means is obtained by a previously performed calculation.
A second rotor initial position estimated value (θ) obtained by adding an arbitrary value (Δθ) to the obtained first rotor initial position estimated value (θo)
There line current control using a 1), after the position control
Won torque command under stop state (Trefp), have row current control using the third rotor initial position estimate obtained by subtracting an arbitrary value ([Delta] [theta]) a (.theta.2), after the position control
To obtain the torque command (Trefn) under the stop state of
By trying a plurality of arbitrary values, | Trefp−Tre
Search for an arbitrary value that minimizes fn |
The corrected value is added to the trochanter initial position estimated value (θo) .

Next, the operation of the above embodiment will be described with reference to FIGS.
This will be described with reference to FIG. In the present invention, an initial setting operation is first performed when the power is turned on, and then a normal operation is performed. However, for the sake of explanation, the normal operation will be described first.

The data stored in each of the memories R ₁ , R ₂ , R ₃ as a current waveform that flows through each of the drive coils 3 u, 3 v, 3 w is as shown in the above equation (2). Further, the torque constants Ktu, Ktv, and Ktw of each phase with respect to the rotor position θf are given by the following equation (3).
Can be thought of as

(Equation 3) Here, from Equation 2, the current flowing in each phase is as shown in Equation 4.

(Equation 4)

The torque Tg generated by the motor is the product of the torque constant and the phase current, and

## EQU5 ##

Tg (θf, θc) = Tref · β · Kt {sin θc · sin θf + sin (θc−120) · sin (θf−120) + sin (θc + 120) · sin (θf + 120)} where θc = θf Assuming that, Tg is as shown in Equation 6.

Tg = (3/2) · Tref · β · Kt Therefore, the motor generates the maximum torque when θc = θf.

[0020] Next, the operation of the counter C _1. Input-output relationship of the counter C ₁ is it is shown in FIG. 6, the counter C ₁ when the number of pulses the rotor 1 is output from the encoder E rotates 1 is 360 is clear, the output .theta.c ₁ is It becomes 0. In addition, 2 of encoder E
The direction of rotation of the rotor is detected from the phase difference between the output pulses of the phases, and up-counting or down-counting is switched according to the direction of rotation. Position θf of such output .theta.c ₁ of the counter C ₁ by the operation of the counter C ₁ and the rotor is always 1
There is a one-to-one correspondence. Therefore, the second switching means SW ₂
Is switched to the contact side, the memories R ₁ , R ₂ , R ₃
Outputs a signal of a current pattern corresponding to the position θf of the rotor, and each of the driving coils 3u, 3v, 3w
, The rotor 1 is driven to rotate. The first switching means SW ₁ is in normal operation is input from the position instruction Pref be in contact side, it is rotationally driven to the position corresponding to the command.

Next, the initial setting operation will be described. FIG. 2 shows the flow of the initial setting operation, and FIG.
Shown in When the power is turned on, since the position of the initial value and the rotor 1 of the counter C ₁ is not turned to the predetermined correspondence relationship, i.e. .theta.c = .theta.f, it detects the position of the rotor by performing an initial operation,
The value θ ₀ corresponding to the position of the rotor is input to the counter C ₁ ,
The initial value of the counter C ₁ is set to the above values theta _0. Less than,
This initial setting operation will be specifically described.

In normal operation, the first and second switching means S
W ₁ and SW ₂ are both contact sides, but are switched to the side when the power is turned on. Therefore, the position command becomes the position command Pref ₀ at the time of the initial operation, and its value becomes 0. Further, when the power is turned position detection means C ₂ is reset, its output is 0
Becomes The difference between the position θf of the rotor and the command signal θc of the current supplied to the coil, that is, θc−θf, is defined as θd. FIG. 7 shows the relationship between this θd and the generated torque Tg, and can be expressed as in Equation 7.

Tg = (3/2) · Tref · β · Kt · cosθd

FIG. 8 is a simplified block diagram of the embodiment shown in FIG. H is the transfer function of the positional deviation amplifier Com ₁ in FIG. 8, I is the speed deviation amplifier Com ₂
Transfer function, N is the position detecting means C ₂ gain, M is the speed detector Sd transfer function of, J is inertia of the motor and load. As is clear from FIGS. 7 and 8, when θd is between 90 ° and 270 °, the feedback of speed and position becomes positive, the control system oscillates and becomes unstable, and the motor runs away. The overrun detection means F is turned on by the runaway of the motor.

In this embodiment, the value of θc is swept while the motor is stopped by the position control loop to change the value of θd. Then, when θd falls within the range of 90 ° to 270 ° from the point indicated by “A” in FIG. 7, runaway starts, and the point at which this runaway starts is detected by the over-rotation detecting means F. Take the value θc ′ of θc. The second logical operation means B ₂ applies the above value θc ′ to Expression 8, finds the rotor position θf at that time, and sets the value as the initial setting value θ ₀ of the counter C ₁ .

[Equation 8] θo = θc′−90

The value obtained by the equation (8) is output as a command signal θc ₂ through the _first logical operation means B ₁ , and the rotor is stopped again by the position control. After confirming the stop, the counter C ₁ is set to the initial value θ ₀ by the second logical operation means B ₂ . Thereafter, the first and second switching means SW ₁ and SW ₂ are switched to the contact side, and the operation shifts to a normal operation. Note that Fth shown in FIG. 9 is a threshold value of the over-rotation detecting means F. The threshold value Fth is set slightly larger than the maximum value of the noise when the position control is operating normally, for example, about 2 pulses, and at most about 5 pulses.

Next, how the above operation is performed in a specific case will be described with reference to FIG. As case 1), it is assumed that θf = −60 ° (300 °). Initially, θc ₂ = 0, so θd = 0−
(−60) = 60. In FIG. 10, the point is “a”,
The sign of Tg is + and the rotor stops. When θc ₂ increases by 1 and θc ₂ = 30 + 1, the rotor starts rotating. Therefore, the initial position θ _{0 of the} rotor is θ ₀ = 30−90 = −60.
(°). However, since θ ₀ = 60 ° <0, θ ₀ = 3
60−60 = 300 (°). Therefore, θ ₀ = θf. Here, -90 in Equation 8 is set to the point at which runaway surely starts,-(90 + 1) =-91.

As case 2), θf = −120 ° (2
40 °). Initially, θc ₂ = 0, so θd = 0 − (− 120) = 120. In FIG. 10, the point is "b", the sign of Tg is-, and the rotor rotates. θ
When c ₂ becomes 180, θd = 180 − (− 120) =
It will be 300. In FIG. 10, the point is "c". θc ₂ is 1
Θc ₂ = (150 + 180 + 1) = 331
At (°), the rotor starts to rotate. Therefore, the rotor position θ ₀ = 331-90 = 240 (°), and θ ₀ = θf.

As case 3), θf = −200 ° (1
60 °). Initially, θc ₂ = 0, so θd = 0 − (− 200) = 200. In FIG. 10, the point is "d", the sign of Tg is-, and the rotor rotates. θ
When c ₂ becomes 180, θd = 180 − (− 200) =
380. In FIG. 10, the point is "e". θc ₂ is 1
When θc ₂ = 180 + 70 = 250 (°), the rotor starts rotating. Therefore, the rotor position θ ₀ = 25
1-91 = 160 (°), and θ ₀ = θf.

As case 4), θf = −345 ° (1
5 °). Initially, θc ₂ = 0, so θd
= 0 − (− 345) = 345. In FIG. 10, the point is "F", the sign of Tg is +, and the rotor stops. θc
_{When 2} increases by 1 and θc ₂ = 105 + 1, the rotor starts rotating. Therefore, the rotor position θ ₀ = 106−90 =
15 (°), and θ ₀ = θf.

In this way, the initial setting operation is performed when the rotor rotates extremely slightly. However, if the initial setting is performed as described above, the initial position is accurately detected when the disturbance torque is applied. Can not do. C
Second logic operating means correcting means included in B ₂ in the PU performs correction according to the disturbance torque to the initial position theta ₀ obtained, sets the correction value again as the initial position theta _0. The basic idea of this correction is that Tg (θd) =
(3/2) Paying attention to the fact that Tref · β · cos θd is an even function, that is, being symmetrical with respect to the T (θd) axis as shown in FIG.
This is to correct the error Δθ caused by l. Hereinafter, this will be described in more detail.

The initial position θ ₀ with the disturbance torque applied
Is completed, the address input to the memories R ₁ , R ₂ , and R ₃ is set to θc ₂ = θ ₀ (the state where the rotor is stopped). Paying attention to the torque command Tref, Tref is the disturbance torque T for stopping the rotor.
It should be a value corresponding to l. That is, Equation 9 is obtained.

Tl = Tref · β · Kt · cos θd ∴Tref = Tl / β · Kt · cos θd

Here, considering the example described with reference to FIG. 13, θd is −30 ° (that is, 0− θer =
-30 °). Then, try adding or subtracting an arbitrary value Δθ in the θ d. If θer = 0, θd
Since = 0, Equation 9 should be changed to Equation 10. This is because cos θd is an even function.

(Equation 10)

However, as in the above example, θer = −3
If it is 0 °, Equation 11 is obtained, and Equation 10 is not established (see FIG. 12).

[Equation 11] Therefore, a new θc that satisfies Equation 10 is obtained,
By setting this to θ 2, the error θer caused by the disturbance torque Tl can be eliminated. This disturbance torque correction operation is performed in the order shown in FIG. First, an estimated position θ 2 of the rotor is obtained and used as an address input θ 2 of the memory. An arbitrary value Δθ is added to the above θ 2, and this is added to the address input θ
c and position control is performed. Wait for a fixed time until the position control system is stabilized, input a torque command Tref,
refp. These operations are shown in FIG.
Shown in Next, an arbitrary value Δθ is subtracted from the above θ 2, and this is used as an address input θc to perform position control. Wait for a certain period of time until the position control system stabilizes, and then
Is input, and this is set as Trefn. These operations are shown in steps 5 to 7 in FIG. Next, Trefp and Tre
The absolute value of the difference between fn is determined, and it is determined in step 8 whether the absolute value is greater than the allowable value ΔTref. FIG.
Shows how .DELTA..theta. Is added or subtracted.

If the absolute value of the difference between Trefp and Trefn is smaller than the permissible value ΔTref, then in step 9 θ _0.
Is set to θc ₂ , and when the rotor stops, θ ₀ is set to the counter C _1, and the estimated value θ _{0 of the} rotor is set as the initial setting value of the magnetic pole position detection counter. If there is no disturbance torque, it corresponds to the case where the absolute value of the difference between Trefp and Trefn is smaller than the allowable value ΔTref.

When the absolute value of the difference between Trefp and Trefn is larger than the allowable value ΔTref, the value of θ ₀ is updated as shown in FIG. That is, Trefp-Tr
determining the sign of efn, a value obtained by subtracting 1 from theta ₀ if positive and theta _0, a value obtained by adding 1 to the theta ₀ if it is negative and theta _0. Based on θ ₀ thus updated, Trefp and Tr
Steps 2 to 8 in FIG. 3 are repeated until the absolute value of the difference of efn becomes smaller than the allowable value ΔTref.

The above operation makes it possible to find θ _{0 at} which the torque command Tref ₁ has the minimum value. The thus obtained θ ₀ has a physical meaning of a value that minimizes a torque command for obtaining a motor torque balanced with the disturbance torque. This will be described using equations with reference to FIG. Since the rotor is stopped, if the disturbance torque is Tl, then Tl = Tg. Further, Tg = 3 · β · cosθd / 2 · Tref 1 _{Therefore, Tref 1 = Tl · 2 /} (3 · β · cosθd) is obtained.

According to the embodiment described above, in the sensorless brushless motor, when calculating the initial position of the rotor, the rotor may be rotated to output a few pulses at the output level of the encoder. Is equivalent to almost no movement, so that it can be applied to those in which the driven object must not move in the initial operation, and can be obtained by a calculation performed in advance.
An arbitrary value (Δ) is added to the first rotor initial position estimated value (θo).
θ) is added to the second rotor initial position estimated value (θ1)
There line current control using a stop-like after the position control
The third rotor initial position estimated value (θ) obtained by obtaining the torque command (Trefp) under the condition and subtracting an arbitrary value (Δθ)
There line current control by using 2) stops after the position control
Won torque command under stop state (Trefn), optionally
| Trefp-Trefn
| Search for any value that minimizes |
Since the correction means for adding the correction value to the initial position estimation value (θo) to provide a correction value is provided, an accurate initial position can be detected regardless of the disturbance torque even when a disturbance torque is applied during the initial operation.

As another embodiment, the output of the speed detector Sd for counting the number of pulses of the speed signal per unit time and detecting the speed is provided to the over-rotation detecting means F in the embodiment of FIG. may be connected to via means C _2, it may be imparted the same function as the speed detector Sd to the position detecting means C _2. Alternatively, the speed detector Sd may detect an analog signal and output a signal that turns on when the speed exceeds a specified speed. Further, it is needless to say that the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof. For example, a method of estimating the initial position of the rotor in advance by calculation is described in Japanese Patent Publication No. 58-119794, in which at least one predetermined coil is energized to bring the rotor to a predetermined stable position. The method may be such that the rotor is rotated to determine the stable position as a specific rotor initial position.

[0039]

According to the present invention, the energizing means is sequentially controlled by the logical operation means to control the exciting current. When the rotor starts rotating and rotates by a predetermined amount or more, this position is detected and the rotor is rotated. In addition to calculating the initial position, the first time obtained by the calculation performed in advance
The rotor initial position estimate (.theta.o), have row current control using the second rotor initial position estimate obtained by adding an arbitrary value ([Delta] [theta]) a (theta 1), stopping after the position control Under the condition, the torque command (Trefp) is obtained and an arbitrary value (Δθ) is obtained.
Gastric line current control by using the third rotor initial position estimate obtained by subtracting (.theta.2), under a stopped state after the position control
Of the torque command (Trefn) of
An arbitrary value that minimizes | Trefp-Trefn | is searched for by performing a pair trial , and this is estimated by the first rotor initial position estimation.
Since the correction means for adding the correction value to the constant value (θo) to provide the correction value is provided, the rotor may be rotated to output a few pulses at the output level of the encoder when calculating the initial position of the rotor. Since it is equivalent to almost no movement, it is possible to apply, for example, to a drive object that should not move in an initial operation such as a robot or a machine tool, and a disturbance torque during the initial operation. , An accurate initial position can be detected irrespective of disturbance torque.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a drive circuit for a brushless motor according to the present invention.

FIG. 2 is a flowchart showing an initial setting operation in the embodiment.

FIG. 3 is a flowchart showing a disturbance torque correction operation in the same initial setting operation.

FIG. 4 is a flowchart showing an initial value update operation accompanying the disturbance torque correction operation;

FIG. 5 is a waveform chart showing the concept of the disturbance torque correction.

FIG. 6 is a timing chart showing the operation of the counter in the embodiment.

FIG. 7 is a diagram illustrating a relationship between a torque and a difference between an exciting current pattern and a rotor position.

FIG. 8 is a simplified block diagram showing the embodiment.

FIG. 9 is a timing chart showing the operation of the embodiment.

FIG. 10 is a diagram for explaining the operation of the embodiment in a more specific case.

FIG. 11 is a diagram showing disturbance torque correction in the embodiment.

FIG. 12 is a diagram showing an initial value updating operation in the embodiment.

FIG. 13 is a diagram showing a deviation of an initial value due to a disturbance torque.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Rotor 5 Position control means E Encoder E Over-rotation detection means d Position command signal B ₁ First logical operation means B ₂ Second logical operation means C ₂ Position detection means

Claims (1)

(57) [Claims] (1) An image obtained by an operation performed in advance
An arbitrary value (Δ) is added to the first rotor initial position estimated value (θo).
θ) is added to the second rotor initial position estimated value (θ1)
There line current control using a stop-like after the position control
The third rotor initial position estimated value (θ) obtained by obtaining the torque command (Trefp) under the condition and subtracting an arbitrary value (Δθ)
There line current control by using 2) stops after the position control
Won torque command under stop state (Trefn), optionally
| Trefp-Trefn
| Search for any value that minimizes |
A drive circuit for a brushless motor, comprising: a correction unit that adds a correction value to an estimated initial position value (θo) .