JPH08182399A - Method for correcting field pole position in synchronous motor - Google Patents

Abstract

PURPOSE: To obtain a corrective value in current phase with small movement in motor without decreasing an accuracy in pole judgment of electromagnetic force, by increasing an electromagnetic force command up to a temporary target, calculating always an acceleration value, and decreasing a target value during large acceleration, while the target value is increased during small acceleration. CONSTITUTION: In correction of a magnetic pole position of a synchronous motor 6, an amount of correction in applied current phase is so changed that a corrective current phase value for making generated electromagnetic force to zero, regardless of the amount of applied current, is judged from polarity acceleration of generated electromagnetic force. After a corrective current-phase value for maximizing the electromagnetic force is obtained from the corrective value, a current phase to be applied is determined from the corrective value and a temporary field pole position detected by a position detector. As a result, the synchronous motor 6 is operated under vector control. In these steps, the acceleration value is always calculated while the electromagnetic command value is increased in a monotonous way up to a temporary target and the target value is decreased during larger acceleration, while the target value is increased during small acceleration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vector control method for a synchronous motor, and more particularly to a field pole position correction method.

[0002]

2. Description of the Related Art Conventionally, in vector control of a synchronous motor, a position detector (resolver or pulse detector) detects a field magnetic pole position and controls the amplitude and phase of a sine wave current having a phase synchronized with the field magnetic pole position. The electromagnetic force control is performed. In general, the field pole position of the synchronous motor and the position of the detection signal of the detector do not always match. Now, the actual field pole position is φ, the detected field pole position is θ, the difference between φ and θ is δ ₁ , the phase of the applied current is ρ, the correction amount of the current phase is γ, and the actual field pole position is φ. When the phase difference between the applied currents is δ, the following expressions (1) to (3) are established. φ = θ + δ ₁ (1) ρ = θ + γ (2) δ = φ−ρ = δ ₁ −γ (3) Further, the size of the field pole is Φ, and the magnitude of the applied current is I.
Then, the generated electromagnetic force T is T = K * Φ * I * cos (δ) (4) However, K is a positive constant. Generated electromagnetic force T
Is the generated torque in the case of a rotary synchronous motor, and is the generated thrust in the case of a direct acting synchronous motor. Hereinafter, description will be made on a rotary synchronous motor. The current phase correction amount γ (= δ ₁ ) at which the generated torque becomes maximum is obtained by shifting the current phase correction amount δ _{0 at} which the generated electromagnetic force T becomes zero by 90 ° regardless of the applied current.

As a method of obtaining the correction amount of the current phase, a method of updating the correction amount γ of the current phase according to the polarity of the generated torque (Japanese Patent Laid-Open No. 61-9218 of the present applicant).
There is 7). In this method, the current phase correction amounts γ ₁ , γ
₂ (where γ ₁ <δ ₀ <γ ₂ ) is the correction amount γ ₃ (eg γ ₃ = (γ
₁ + γ ₂ ) / 2) is given, the polarity of the generated torque is investigated,
If the polarity of the generated torque at this time is different from the polarity of the generated torque at the lower limit correction amount γ ₁ , the upper limit correction amount γ
₂ is updated with the correction amount γ ₃ , and when the generated torque has a polarity different from that of the upper limit correction amount γ ₂ , the lower limit correction amount γ ₁ is updated with the correction amount γ ₃ . The final value of the correction amount γ obtained by repeating this process a predetermined number of times is δ ₀ . As a method for determining the polarity of the generated torque, there are JP-A-61-92187 and JP-A-62-31385 proposed by the present applicant. In the former case, the polarity of the generated torque is positive when the speed feedback is negative feedback and the polarity of the generated torque is negative when the speed feedback is positive feedback. In the latter, the polarity of the generated torque is positive when the sign of the torque command and the sign of the speed change (acceleration) match, and negative when they do not match. The maximum torque command is given as the torque command.

[0004]

However, whichever method is used, the correction amount of the current phase is obtained by using only the polarity of the generated torque. Therefore, when the torque command to be used is increased, the amount of movement of the motor is increased. Becomes larger and the torque command to be used becomes smaller, the accuracy of determining the polarity of the generated torque becomes worse. The object of the present invention is to reduce the movement of the electric motor,
Another object of the present invention is to provide a method for correcting a magnetic pole position of a synchronous motor, which can obtain a correction amount of a current phase without lowering the accuracy of determining the polarity of a generated electromagnetic force.

[0005]

According to the method of correcting the position of the magnetic poles of the synchronous motor of the present invention, the correction amount (γ) of the phase (ρ) of the applied current is changed to change the magnitude of the applied current. The amount of current phase correction (δ ₀ ) at which the generated electromagnetic force becomes zero
Is determined by determining the polarity of the generated electromagnetic force from the polarity of the acceleration, and the current phase correction amount (δ ₀ ) is used to derive the current phase correction amount (δ ₁ ) that maximizes the generated electromagnetic force. In the method of vector-controlling the synchronous motor by determining the phase (ρ) of the current to be applied from the correction amount (δ ₁ ) of the current phase and the temporary field pole position (φ) detected by the position detector, Is monotonically increased to a tentative target value and the acceleration is calculated at any time, and when the acceleration is large, the target value is reduced,
The feature is that the target value is increased when the acceleration is small.

Another field magnetic pole position correction method for a synchronous motor according to the present invention is to change the correction amount (γ) of the phase (ρ) of the applied current to generate an electromagnetic force regardless of the magnitude of the applied current. The current phase correction amount (δ ₀ ) at which is zero is determined by determining the polarity of the generated electromagnetic force from the polarity of the acceleration, and the correction amount (δ ₀ ) is used to obtain the current phase correction amount that maximizes the generated electromagnetic force. (Δ ₁ ) is derived, the phase (ρ) of the current to be applied is determined from this current phase correction amount (δ ₁ ) and the temporary field pole position (φ) detected by the position detector, and the synchronous motor is set as a vector. In the control method, the electromagnetic force command is monotonously changed from 0 to a first target value, symmetrically changed to 0 with the time of the first target value as an axis, and then the electromagnetic force command 0 is used as an axis. Symmetrically, the first target value and the second target value having the same absolute value but different polarities are changed, It changes monotonically again to 0,
Furthermore, contrary to the past, the electromagnetic force command is changed to the second target value,
It is characterized in that 0, the first target value, and 0 are changed.

[0007]

Therefore, when the acceleration is large, the generated electromagnetic force is large, so that the disturbance can be overcome even if the electromagnetic force command is reduced, and as a result, the rotation amount (movement amount) can be reduced. Further, when the acceleration is small, the rotation amount (movement amount) is naturally small, so that the electromagnetic force command can be increased and the accuracy of determining the polarity of the generated electromagnetic force can be increased.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 3 is a block diagram showing a circuit configuration of a drive device by vector control of a synchronous motor (three phases) to which the method for correcting a magnetic field pole position of the synchronous motor of the present invention is applied.
The encoder 7 detects the rotational position of the synchronous motor 6.
The microprocessor 1 performs calculation using the torque command i and the position x of the synchronous motor 6 detected by the counter 8,
Two-phase current commands Iu and Iv are applied to the D / A converter 2,
Digital / analog conversion is performed by 3 and output to the 2-phase / 3-phase conversion circuit 4. The 2-phase / 3-phase conversion circuit 4 converts the input 2-phase current command into 3-phase current commands iu, iv, and iw, and controls the power amplifier 5. The power amplifier 5 is
Currents corresponding to these three-phase current commands iu, iv, and iw are supplied to the synchronous motor 6 to drive the synchronous motor 6.

FIG. 4 is a block diagram of the microprocessor 1. The field pole position calculator 101 calculates a temporary field pole position θ from the position information x. The speed calculator 102 calculates the speed based on the time difference (differentiation) of the position information x. The acceleration calculator 103 calculates acceleration by the time difference (differentiation) of the speed information of the speed calculator 102. Torque command generator 10
4 generates a torque command i according to a pattern described later during the estimation of the field pole position correction amount, and after the estimation, generates a torque command i according to the control. The torque polarity determiner 105 determines the sign of cos (δ) related to the phase difference δ between the actual field pole position φ and the phase ρ of the current command to be applied based on the acceleration information. That is, the torque polarity determiner 105 determines that the current phase correction amount γ ₁ is being estimated while the current phase correction amount δ ₁ is being estimated.
On the other hand, first, the speed change (acceleration) Acc1 when the torque command is 0 is stored. Acc1 is acceleration due to disturbance. Here, the acceleration Acc1 is compared with the preset acceleration Acc2, and the larger one is set as the reference acceleration Acc0 for determining the magnitude of the acceleration. If possible, Acc0
Is 5% or more larger than Acc1. The acceleration Acc3 is calculated at regular intervals, and the polarity of the generated torque is determined by the sign of the acceleration when it becomes larger than the reference acceleration Acc0. Even if the command becomes the maximum torque command, if the acceleration Acc3 is smaller than the reference acceleration Acc0, the polarity of the generated torque is determined by the sign of the acceleration Acci at that time. The accelerations Acc1 and Acc3 are the acceleration calculator 1
03 measures. The current phase corrector 106 estimates the current phase correction amount δ ₀ by the method described later, and the current phase correction amount γ = δ ₁ (= δ ₀ +9 so that the polarity of the generated torque becomes positive.
0 °) or γ = δ ₁ (= δ ₀ −90 °) is output.
The adder 107 adds the provisional field magnetic pole position θ output from the field magnetic pole position calculator 101 and the current phase correction amount γ output from the current phase corrector 106, and outputs the phase ρ of the applied current. The phase ρ of this current is converted to sin (ρ) by the sine function generator 110. Further, the current phase ρ and the output of the −120 ° generator 108 are added by the adder 109 to obtain ρ−120 °, and the sine function generator 11
It is converted into sin (ρ-120 °) by 1. The sine function generators 110 and 111 give the applied current phases ρ and ρ−120 ° as addresses, respectively,
It is possible to take out the sin function stored in the program memory. The multipliers 112 and 113 respectively add s to the torque command i output from the torque command generator 104.
The two-phase current commands Iu and Iv are output by multiplying in (ρ) and sin (ρ-120 °).

Next, the current phase correction amount δ in this embodiment.
₁ The estimation method of is referred to the flowchart of FIG.
explain. (Processing 21) Initial values are set. That is, current level complementation
Positive amount γ = 0 °, number of estimations j = 1, time t = −m · Δt
(= T_-1). However, m is a positive integer. time
t is the basis of processing such as calculation of torque command i and measurement of acceleration.
It is a quasi-time. Go to process 22. (Processing 22) The torque command i is calculated by the method described later. place
Proceed to reason 23. (Processing 23) The time t is determined. If t = 0, process 2
Go to 4. If t = k · Δt, the process proceeds to step 26. t =
t_1MAXIn the case of, the processing proceeds to processing 28. t = t₈ (T ₈ = 8
t_1MAXIn the case of), the process proceeds to process 32. Others, process 31
Proceed to. However, k is a positive integer and k · Δt <t_1MAXso
is there. t_1MAXIs the torque command i_MAX At the time
It

(Processing 24) The acceleration Acc1 is measured.
Go to processing 25. (Processing 25) The absolute value of the acceleration Acc1 is compared with the preset acceleration Acc2 (> 0), and the larger value is set as the reference acceleration Acc0 (> 0). Go to processing 31. (Processing 26) The acceleration Acc3 is measured. Go to processing 27. (Process 27) Absolute value of acceleration Acc3 and reference acceleration Ac
Compare c0. If | Acc3 | is greater than Acc0, the process proceeds to step 29, and if not, the process proceeds to step 31. (Processing 28) The acceleration Acc3 is measured. Go to processing 29. (Processing 29) The current phase correction amount γ is updated by the method described later. Go to processing 30.

(Process 30) A reference time t ₁ for creating the torque command i is determined. Let t ₁ = t. Here, t is either time the absolute value of the acceleration Acc3 is larger than the reference acceleration Acc0, a t _1MAX. Go to processing 31. (Processing 31) The time is updated. Let t = t + Δt. Go to process 22. (Process 32) The time is returned to the initial value. Let t = −m · Δt. Go to process 33. (Process 33) The estimated number of times j is compared with the maximum estimated number of times j _mAX . If j is smaller than j _{mAX, the} process proceeds to step 34, and if not, the process proceeds to step 35. (Processing 34) The estimated number of times j is updated. Let j = j + 1. Go to process 22. (Processing 35) The current phase correction amount δ ₁ is determined by the method described later. The process ends.

Next, the current phase correction amount γ is updated according to FIG.
I will explain how to do. (Processing 41) The estimation number j is determined. If j = 1, then
In reason 42, j = 2 to j _mAX In the case of, the processing proceeds to processing 45.
From the description of FIG. 1, j> j_mAX Never be. (Process 42) The sign of the acceleration Acc3 is checked. Acc3
If ≧ 0, the process proceeds to step 43. When Acc3 <0
Proceeds to process 44. (Processing 43) Limit value at which positive acceleration is obtained (hereinafter,
Abbreviated as limit value) γ_p , The limit value for negative acceleration (below
Below, abbreviated as negative limit value) γ_m To initialize. γ _p = 0
°, γ_m = 180 °. Go to process 48. Note that γ
_p Is δ when it is determined that the acceleration Acc3 ≧ 0₀ Most
Insert a close current phase correction amount γ. γ_m Is the acceleration Acc3
Δ when it is judged as <0₀ Current phase correction amount closest to
Insert γ.

(Processing 44) The positive limit value γ _p and the negative limit value γ _m are initialized. _Let γ _p = 180 ° and γ _m = 0 °. Go to process 48. (Processing 45) The sign of the acceleration Acc3 is checked. Acc3
If ≧ 0, the process proceeds to process 46. If Acc3 <0, the process proceeds to process 47. (Processing 46) The positive limit value γ _p is updated. _Let γ _p = γ. Go to process 48. (Processing 47) The negative limit value γ _m is updated. Let γ _m = γ. Go to process 48. (Processing 48) The current phase correction amount γ used next is calculated. _Let γ = (γ _p + γ _m ) / 2. The process ends. Next, a method of generating the torque command i will be described with reference to FIG. The time divisions t _{2 to} t ₈ are determined as follows based on t ₁ determined in the process 30.

T ₂ = 2 · t ₁ t ₃ = 3 · t ₁ t ₄ = 4 · t ₁ t ₅ = 5 · t ₁ t ₆ = 6 · t ₁ t ₇ = 7 · t ₁ t ₈ = 8 · The t ₁ torque command i is determined as follows. When t ₋₁ ≦ t <0, i = 0. t ₋₁ = −m · Δt. 0 ≦
When t <t ₁ , i = f (t). Function f (t)
Is f (0) = 0 and f (t ₁ ) = i _MAX , and the interval 0 ≦
It is assumed that it increases monotonically when t ≦ t ₁ . Note that i _MAX is preferably a maximum torque command, but it may be smaller than the maximum torque command. For example, 90% of maximum torque command or 5
0% is sufficient.

T₁ ≤t <t₂ , I = f (t₂ −
t). t₂ ≤t <t₃ , I = -f (t-
t₂ ). t₃ ≤t <t_Four , I = -f (t
_Four -T). t_Four ≤t <t_Five When, i = -f
(T-t_Four ). t_Five ≤t <t₆ When, i =-
f (t₆ -T). t₆ ≤t <t₇ When, i =
f (t-t₆ ). t₇ ≤t <t₈ When, i =
f (t₈ -T). FIG. 6 shows the primary function as f (t).
In an example using numbers, t₁ = T_1MAXIs the case. f (t) = i_MAX / T_1MAX• t Figure 7 uses the same f (t) as Figure 6, but t is t
_1MAXIf | Acc3 |> Acc0 before
And t₁ = T_{1 MID}(<T_1MAX) Is an example. Toll
The absolute value of the target value of the command i is the time t₁ Torque at
Command i_MID (<I _MAX )become. In addition, the torque command i
Time to give is 8t_1MAX+ T_-1From 8 ・ t _{1 MID}+ T_-1To
Will be shortened.

FIG. 8 is a diagram for explaining a method for obtaining the current phase correction amount δ ₁ that gives the maximum torque from the current phase correction amount δ _{0 at} which the generated torque becomes 0 regardless of the magnitude of the applied current. In FIG. 8, the shaded portion is the range of the current phase correction amount γ where Acc3 ≧ 0. Current phase correction amount γ =
The following combinations are possible depending on the sign of the acceleration Acc3 at 0 °. (1) When Acc3 ≧ 0 (corresponding to (1) and (4) in FIG. 8) δ ₁ = δ ₀ −90 ° (2) When Acc3 <0 (corresponding to (2) and (3) in FIG. 8) δ ₁ = δ ₀ + 90 ° Note that δ ₀ is always found between 0 ° and 180 °.

Although the rotary synchronous motor has been described above, the same can be said for a direct acting synchronous motor by replacing the torque with the thrust.

[0019]

As described above, the present invention has the following effects. (1) The invention of claim 1 changes the electromagnetic force command given in accordance with the magnitude of the acceleration to change the rotation amount (movement amount).
It is possible to obtain the correction amount of the current phase without reducing the accuracy of the determination of the polarity of the generated electromagnetic force. (2) According to the invention of claim 2, the velocity can be returned to the same as the start time by the 0 command after the second target value, so that the position can be returned to the same as the start time by the last 0 command. . If the disturbance does not change even if the correction amount of the current phase is changed, the polarity of acceleration can be determined under the same conditions. (3) In the invention of claim 3, the function can be easily generated. (4) According to the invention of claim 4, the electromagnetic force command is reduced when the acceleration is large, so that the rotation amount (movement amount) is smaller than when the provisional target value is maintained. (5) According to the invention of claim 5, the reference acceleration is made larger than the acceleration due to the disturbance, so that the mistake of the electromagnetic force polarity determination due to the disturbance can be eliminated. (6) According to the invention of claim 6, the disturbance acceleration at the immediately preceding 0 command can be measured for each correction amount, so that it is possible to cope with the change in the disturbance.

[Brief description of drawings]

FIG. 1 is a flowchart showing an embodiment of the present invention.

FIG. 2 is a flowchart showing a method of updating a current phase correction amount according to the present invention.

FIG. 3 is a block diagram showing a circuit configuration of synchronous motor vector control to which the present invention is applied.

FIG. 4 is a block diagram showing a microprocessor 1.

FIG. 5 is a diagram illustrating a method of generating a torque command according to the present invention.

FIG. 6 is a diagram illustrating a case where a torque command of the present invention is generated using a linear function.

FIG. 7 is a diagram illustrating a torque command of the present invention generated using a linear function,
It is a figure explaining the case where acceleration is large and thrust command does not require up to i _MAX .

FIG. 8 is an explanatory diagram for obtaining a current phase correction amount δ ₁ of the present invention.

[Explanation of symbols]

 1 Microprocessor 2, 3 D / A converter 4 2/3 phase conversion circuit 5 Power amplifier 6 Synchronous electric motor 7 Encoder 8 Counter 21-35, 41-48 Processing 101 Speed detector 102 Acceleration detector 103 Torque polarity determiner 104 Torque command generator 105 Temporary magnetic pole position detector 106 Current phase corrector 107-120 ° generator 108,109 Adder 110,111 Sine function generator 112,113 Multiplier

Claims (6)

[Claims] 1. A current phase correction amount (δ ₀ ) at which the generated electromagnetic force becomes zero regardless of the magnitude of the applied current, by changing the correction amount (γ) of the applied current phase (ρ). Obtained by determining the polarity of the generated electromagnetic force from the polarity of acceleration,
The current phase correction amount (δ ₁ ) is used to derive the current phase correction amount (δ ₁ ) that maximizes the generated electromagnetic force, and the current phase correction amount (δ ₁ ) and the temporary detector detected by the position detector are derived. In the method of determining the phase (ρ) of the current to be applied from the field pole position (φ) and vector-controlling the synchronous motor, the electromagnetic force command is monotonically increased to a provisional target value to obtain the acceleration at any time, A method of correcting a magnetic field pole of a synchronous motor, comprising: decreasing the target value when the acceleration is large and increasing the target value when the acceleration is small. 2. A correction amount (γ) of the phase (ρ) of the applied current is changed so that a current phase correction amount (δ ₀ ) at which the generated electromagnetic force becomes zero regardless of the magnitude of the applied current, Obtained by determining the polarity of the generated electromagnetic force from the polarity of acceleration,
The current phase correction amount (δ ₁ ) is used to derive the current phase correction amount (δ ₁ ) that maximizes the generated electromagnetic force, and the current phase correction amount (δ ₁ ) and the temporary detector detected by the position detector are derived. In the method of vector-controlling the synchronous motor by determining the phase (ρ) of the applied current from the field magnetic pole position (φ), the electromagnetic force command is changed monotonically from 0 to the first target value,
Of the target value is symmetrically changed to 0 about the time, and then the electromagnetic force command 0 is changed symmetrically to the second target value whose polarity is different from that of the first target value in absolute value. , A monotonic change again to 0, and further, the electromagnetic force command is changed to a second target value, 0, a first target value, 0 in a completely opposite manner to the above, the field pole of the synchronous motor. Correction method. 3. The method of correcting a magnetic field pole position of a synchronous motor according to claim 1, wherein the function for giving the electromagnetic force command is a linear curve in a monotonically changing section. 4. The acceleration is sequentially detected while the electromagnetic force command is being changed from 0 to a temporary first target value, and if the magnitude of the acceleration becomes larger than a reference acceleration, the first acceleration is detected. The method of correcting a magnetic field pole position of a synchronous motor according to claim 2, wherein the target value is changed to an electromagnetic force command at that time. 5. The field pole position correcting method for a synchronous motor according to claim 4, wherein a value larger than the acceleration when the electromagnetic force command is 0 is used as the reference acceleration. 6. The method of correcting a magnetic field pole position of a synchronous motor according to claim 2, wherein a section of electromagnetic force command 0 is provided between a certain correction amount and a next correction amount.