JP2007068255A - Initial phase estimator for permanent magnet synchronous motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an initial phase estimator to which a function of judging whether the judgment of a magnetic pole judger is right or wrong is added and which improves the accuracy in phase estimation by estimating a specified phase again in case that it has made a mistake, thus estimating the phase of the rotor of a permanent magnet synchronous motor at stoppage. <P>SOLUTION: The magnetic pole judger has a function of judging whether its judgment is successful or unsuccessful, and in case that it judges the magnetic pole to be unsuccessful, it slides the initial value of a phase converger by a specified value and reestimates the phase of an axis d over again. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to rotor phase estimation when a permanent magnet synchronous motor is stopped, and particularly proposes a technique for eliminating phase estimation failure.

FIG. 3 shows an initial phase estimating apparatus for a permanent magnet synchronous motor as an example, and the prior art will be described based on this figure.
The power converter 1 supplies power to the permanent magnet synchronous motor 2 based on the input signal S. The current detector 3 detects the input current of the permanent magnet synchronous motor 2. The voltage detector 4 detects the input voltage of the permanent magnet synchronous motor 2. When the phase (direction) of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor 2 is the d axis and the estimated phase of the N pole of the permanent magnet is the γ axis, the phase converging unit 5 , An output of the current detector 3 and an output of the voltage detector 4 are input, and a signal S or an arbitrary voltage that allows an arbitrary current to flow through the permanent magnet synchronous motor 2 is applied. The phase of the signal S, the d-axis phase, and the γ-axis phase is gradually corrected for a predetermined period so that the phase difference converges to 0 degree or 180 degrees, and the γ-axis phase is output. The magnetic pole discriminator 6 inputs the phase of the γ-axis and the γ-axis component of the input voltage, which are the outputs of the phase converging unit 5, and sets the γ-axis component of the input current to 0 and the δ-axis component orthogonal to the γ-axis phase. When the phase difference is determined to be 0 degree or 180 degrees with respect to the signal S through which the predetermined value I flows, and when the phase difference is determined to be 0 degree, the output of the phase converging device 5 is determined to be 180 degrees Outputs a value obtained by adding 180 degrees to the output of the phase converging device 5 as the phase of the γ axis. First, the switch 7 outputs the signal S output from the phase converging device 5 to the power converter 1, and when a predetermined period in which the phase converging unit 5 converges the phase difference to 0 degree or 180 degrees has elapsed, the switch 7 The signal S output from the determiner 6 is output to the power converter 1.

Hereinafter, a method for estimating the d-axis phase, which is the N-pole phase of the permanent magnet of the rotor of the permanent magnet synchronous motor 2, by the phase converging device 5 will be described. The voltage equation of the permanent magnet synchronous motor 2 with the estimated d-axis as the γ-axis and the estimated q-axis as the δ-axis can be expressed as follows.

Vγ = (R + ω · Lγδ + p · Lγ) · iγ
− (Ω · Lδ + p · Lγδ) · iδ−ω · φ · sin (Δθ) (1)
Vδ = (ω · Lγ−p · Lγδ) · iγ
+ (R−ω · Lγδ + p · Lδ) · iδ + ω · φ · cos (Δθ) (2)
Lγ = [Ld + Lq− (Lq−Ld) · cos (2 · Δθ)] / 2 (3)
Lδ = [Ld + Lq + (Lq−Ld) · cos (2 · Δθ)] / 2 (4)
Lγδ = (Lq−Ld) · sin (2 · Δθ) / 2 (5)

  Here, Vγ and Vδ are the input voltages of the components of the γ-axis and δ-axis, iγ and iδ are the input currents of the components of the γ-axis and δ-axis, respectively, R is the armature winding resistance of the permanent magnet synchronous motor 2, and ω Is the rotational angular frequency of the permanent magnet synchronous motor 2, p is the differential operator, Ld and Lq are the d-axis inductance and q-axis inductance of the permanent magnet synchronous motor 2, respectively, φ is the flux linkage to the armature by the permanent magnet, Δθ Is the phase difference, and if the phase of the d-axis is θr and the phase of the γ-axis is θ, Δθ = θr−θ.

Substituting Equations (3), (4), and (5) into Equation (1) and approximating cos (2 · Δθ) = 1 and sin (2 · Δθ) = 2 · Δθ, the phase difference Δθ is Become.

Δθ = (− Vδ + ω · Ld · iγ + R · iδ + Lq · p · iδ + ω · φ) /
[(Lq−Ld) · p · iγ + ω · (Lq−Ld) · iδ] (6)

If the phase θ of the γ-axis is adjusted by the phase converging unit 5 so that the phase difference Δθ becomes 0, the d-axis and the γ-axis coincide with each other, and the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor 2 The d-axis that is the phase can be estimated.

However, since the phase difference Δθ is used twice as shown in the equations (3), (4), and (5), the difference between the phase difference of 180 degrees and the phase difference of 0 degrees can be distinguished in these expressions. It will not be possible. In other words, if the absolute value of the initial phase difference is less than 90 degrees, the phase difference can be reduced to 0 degree by adjusting θ so that Δθ obtained by the equation (6) becomes 0. If the absolute value of the phase difference exceeds 90 degrees, the phase difference will converge to 180 degrees. Therefore, the magnetic pole determiner 6 is necessary. A method for determining whether the phase difference is 0 degree or 180 degrees by the magnetic pole determiner 6 will be described below.

When iγ = 0 and iδ = I (direct current) are passed in the state of Δθ = 0 or 180 degrees, the γ-axis voltage Vγ is as follows from the equation (1).

  Vγ = −ω · Lδ · iδ (7)

The torque equation of the permanent magnet synchronous motor 2 is

  T = n · [iq · φ + (Ld−Lq) · id · iq] (8)

It is represented by Here, n is the number of pole pairs of the permanent magnet synchronous motor 2. Therefore, when the phase difference Δθ = 0 degrees, iq = iδ, and if I> 0, the permanent magnet synchronous motor 2 accelerates in the positive direction to generate a positive torque. That is, ω> 0, and Vγ <0 from equation (7). Therefore, if the signs of ω and Vγ are different from each other, the phase difference Δθ can be determined to be 0 degree, and if the signs of ω and Vγ are the same sign, the phase difference Δθ can be determined to be 180 degrees.

Patent Document 1 describes a method for determining whether the phase difference is 0 degree or 180 degrees by a method other than the above.
A method of determining the phase difference from the sign of I and the integral value of the γ-axis voltage Vγ when the absolute value of the value obtained by integrating the γ-axis voltage Vγ by time integration exceeds a predetermined value.
A method of determining the phase difference from the integral value of the γ-axis voltage Vγ and the sign of ω.
A method of determining a phase difference from the difference between the γ-axis voltage Vγ1 after the lapse of the predetermined time t1 and the γ-axis voltage Vγ2 after the lapse of the predetermined time t2 Vγ2−Vγ1 and I.
Γ-axis voltage Vγ is time-integrated with an initial value 0 every minute period Δt, and an integrated value φd1 after a predetermined time t3 has elapsed is stored, and φd1 and a value φdn time-integrated with an initial value 0 every minute period Δt A method of determining a phase difference from the sign of φdn−φd1 and the sign of I when the absolute value of the difference exceeds a predetermined value.

Patent Document 2 describes a method for estimating the d-axis phase based on principles and methods other than Patent Document 1 and a method for determining whether the phase difference is 0 degrees or 180 degrees.
FIG. 4 shows an initial phase estimating apparatus for a permanent magnet synchronous motor as an example, and the prior art of Patent Document 2 will be described based on this figure.
What is different from the prior art of FIG. 3 described above is a phase converging unit 5 ′ and a magnetic pole determining unit 6 ′. When the phase (direction) of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor 2 is the d axis and the estimated phase of the N pole of the permanent magnet is the γ axis, the phase converging unit 5 ′ An arbitrary initial value of the phase, the output of the current detector 3 and the output of the voltage detector 4 are input, an arbitrary alternating current is passed through the permanent magnet synchronous motor 2 as the γ-axis current iγ, and the δ-axis current iδ is set to 0. The phase of the γ-axis is output after being gradually corrected for a predetermined period so that the phase difference between the signal S and the phase of the d-axis and the phase of the γ-axis converges to 0 degree or 180 degrees. The magnetic pole discriminator 6 ′ inputs the phase of the γ-axis, the γ-axis component of the input voltage, and the γ-axis component of the input current, which are the outputs of the phase converging unit 5 ′, and the γ-axis component of the input current is a predetermined positive value. It is determined whether the phase difference is 0 degree or 180 degrees with the signal S in which a predetermined negative value flows, and if the phase difference is determined to be 0 degree, the output of the phase converging device 5 ′ is 180 degrees. Is determined, a value obtained by adding 180 degrees to the output of the phase converging unit 5 ′ is output as the phase of the γ axis.

A method for estimating the d-axis phase, which is the N-pole phase of the permanent magnet of the rotor of the permanent magnet synchronous motor 2, by the phase converging device 5 'will be described below.
Although the derivation of the equation is omitted, the R term in the equations (1) and (2) is omitted, the equation (3) is Lγ = Ld, the equation (4) is Lδ = Lq, the equation (5) is Lγδ = By approximating 0, the phase difference Δθ is obtained from the detected γ-axis current iγ and δ-axis voltage vδ by the following equation.

Δθ = iγ · p · vδ−p · iγ · vδ
= −ω1 · ω1 · I1 · I1 · (Lq−Ld) sin (2 · Δθ) (9)

In the formula (9), the phase difference Δθ is doubled, so that the phase difference of 180 degrees cannot be distinguished from the phase difference of 0 degrees.
Therefore, the magnetic pole determiner 6 ′ for determining the phase difference is required. In this method, the γ-axis current iγ is passed until a positive predetermined value (Ip) is reached, and then the negative predetermined value (−Ip) is passed, and the detected γ-axis current iγ and the detected γ-axis voltage vγ are used. The inductance is obtained, and if the relationship between the inductance Ldnp when flowing until it reaches a positive predetermined value (Ip) and the inductance Ldn when flowing until it reaches a negative predetermined value (−Ip) is Ldp> Ldn, It is determined that the phase difference is 180 degrees. The principle of this determination uses a magnetic saturation phenomenon caused by a magnetizing action and a demagnetizing action by a magnetic flux and a permanent magnet magnetic flux caused by the flow of a γ-axis current iγ.

Patent No. 3480572 Japanese Patent No. 3566595

  As a method for estimating the phase of the d-axis, Lq−Ld, that is, the difference between Ld and Lq is used as expressed by the equations (6) and (9). Therefore, in a permanent magnet synchronous motor with a small difference between Ld and Lq, the phase converging unit 5 or the phase converging unit 5 ′ cannot converge the phase difference Δθ to 0 degrees or 180 degrees in a predetermined period, and the magnetic pole determination unit 6 or the magnetic pole determiner 6 ′ cannot determine whether the phase difference Δθ is 180 degrees or 0 degrees, or results in incorrect determination.

  In order to solve the above problems, the present invention newly adds a function for determining whether or not the judgment of the magnetic pole discriminator is correct, and if it is wrong, the phase estimation accuracy is improved by performing the predetermined phase estimation again. An object of the present invention is to provide an initial phase estimation device for a permanent magnet synchronous motor.

  In order to solve the above-mentioned problems, the phase (direction) of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor is set as the d-axis with the permanent magnet synchronous motor stopped, and the N pole of the permanent magnet Assuming that the estimated phase of γ is the γ axis, an arbitrary initial value of the phase of the γ axis is input so that the phase difference between the phase of the d axis and the phase of the γ axis converges to 0 degrees or 180 degrees. A phase converging device that gradually corrects and outputs the phase of the γ-axis for a predetermined period and an output of the phase converging device are input to determine whether the phase difference is 0 degree or 180 degrees, and the phase difference is 0 A magnetic pole determiner that outputs the output of the phase converging device as it is when it is determined to be 180 degrees and adds 180 degrees to the output of the phase converging device when it is determined to be 180 degrees, The phase concentrator and the magnetic pole determiner are operated in this order to estimate the d-axis phase. In the initial phase estimation device for a permanent magnet synchronous motor, the magnetic pole determination device is provided with a function of determining whether the determination of the magnetic pole determination device is successful or unsuccessful. The initial value is shifted by a predetermined value, and the phase of the d-axis is estimated again.

  According to the present invention, the phase of the N pole of the rotor of the permanent magnet synchronous motor can be accurately estimated.

  Even with a permanent magnet synchronous motor having a small difference between Ld and Lq, the phase of the N pole of the rotor in a stopped state could be estimated.

FIG. 1 is a block diagram of one embodiment of the present invention.
What is different from the prior art of FIG. The phase converging unit 8 newly inputs the signal J of the magnetic pole discriminator 9 and if the signal J is 1, the initial value of the phase of the γ-axis is shifted by a predetermined value, and again to the permanent magnet synchronous motor 2 The signal S to which an arbitrary current flows or the signal S to which an arbitrary voltage is applied and the phase difference between the phase of the d-axis and the phase of the γ-axis gradually converges for a predetermined period so as to converge to 0 degree or 180 degrees. Correct and output the phase of γ-axis. The magnetic pole discriminator 9 inputs the γ-axis phase and the γ-axis component of the input voltage, which are the outputs of the phase converging unit 8, and sets the γ-axis component of the input current to 0 and the δ-axis component orthogonal to the γ-axis phase. When the phase difference is determined to be 0 degree or 180 degrees from the signal S through which the predetermined value I flows, and when the phase difference is determined to be 0 degree, the output of the phase converging unit 8 is determined to be 180 degrees Outputs a value obtained by adding 180 degrees to the output of the phase converging unit 8 as the phase of the γ axis, and newly determines whether the phase difference determination is successful or unsuccessful, and if successful, outputs a signal J that is 1 if 0 is unsuccessful. .

Below, the method to determine whether the determination result of the magnetic pole determination device 9 which is a function added to the magnetic pole determination device 9 is success or failure will be described.
As described above, in the magnetic pole determiner 6, the phase difference Δθ is 180 degrees or 0 based on the relationship between the signs of ω and Vγ, which are derived from the torque equation (8) and the voltage equation (7). Judging the degree. However, the permanent magnet synchronous motor 2 may not be able to rotate unless the phase θ estimated by the phase converging unit 5 is 180 ° or 0 °. If the phase difference Δθ is not 180 degrees or 0 degrees, iq = iδ is not satisfied, the torque that can be output from the permanent magnet synchronous motor 2 is reduced from the equation (8), and the permanent magnet synchronous motor 2 cannot rotate ( This is because Vγ = 0 from the equation (7) and it is impossible to determine whether the phase difference Δθ is 180 degrees or 0 degrees.
Therefore, if the absolute value of ω does not exceed the predetermined value X after flowing for a predetermined time with the γ-axis component of the input current as 0 and the δ-axis component as the predetermined value I, the determination result is determined as failure. Alternatively, if the absolute value of Vγ does not exceed the predetermined value V after the predetermined time, the determination result is determined as failure.

  When the determination result of the magnetic pole determiner 9 is determined to be unsuccessful, the initial value of the phase of the γ-axis that is the input of the phase converging unit 8 is shifted by a predetermined value, and the d-axis phase is estimated again. Even if the difference between Ld and Lq is small, the phase of the d-axis output by the phase converging unit 8 can be brought as close as possible to the phase difference Δθ = 180 degrees or 0 degrees, and the determination result of the magnetic pole determination unit 9 can be made successful. Thus, the phase of the d axis can be estimated.

Although other examples are described in Patent Document 1, for example,
Whether the determination result of the magnetic pole determiner is successful or unsuccessful is determined by whether or not the absolute value of the time integral value of the γ-axis voltage Vγ after a predetermined time has passed exceeds a predetermined value.
・ The judgment result of the magnetic pole discriminator is successful or unsuccessful depending on whether or not the absolute value of the difference Vγ2−Vγ1 between the γ-axis voltage Vγ1 after the lapse of the predetermined time t1 and the γ-axis voltage Vγ2 after the lapse of the predetermined time t2 exceeds the predetermined value. Determine whether.
Γ-axis voltage Vγ is time-integrated with an initial value 0 every minute period Δt, and an integrated value φd1 after a predetermined time t3 has elapsed is stored, and φd1 and a value φdn time-integrated with an initial value 0 every minute period Δt Whether the determination result of the magnetic pole determiner is successful or unsuccessful is determined based on whether or not the absolute value of the difference exceeds a predetermined value.
There are various methods for determining whether the determination result of the pole determiner 9 is success or failure.

FIG. 2 is a block diagram of one embodiment of the present invention.
What is different from the prior art of FIG. 4 is a phase converging unit 8 ′ and a magnetic pole determining unit 9 ′. The phase converging unit 8 ′ additionally inputs the signal J of the magnetic pole discriminator 9 ′. If the signal J is 1, the permanent magnetic synchronous motor is shifted again by shifting an arbitrary initial value of the phase of the γ axis by a predetermined value. 2 for a predetermined period so that the phase difference between the signal S and the phase of the d-axis and the phase of the γ-axis converges to 0 degrees or 180 degrees. Correct gradually and output the phase of γ-axis. The magnetic pole determiner 9 ′ inputs the phase of the γ-axis, the γ-axis component of the input voltage, and the γ-axis component of the input current, which are the outputs of the phase converging unit 8 ′, and the γ-axis component of the input current is a predetermined positive value. It is determined whether the phase difference is 0 degree or 180 degrees with the signal S in which a predetermined negative value flows, and if the phase difference is determined to be 0 degree, the output of the phase converging unit 8 'is 180 degrees. Is determined, the value obtained by adding 180 degrees to the output of the phase converging unit 8 ′ is output as the phase of the γ axis, and it is newly determined whether the phase difference determination is successful or unsuccessful. A signal J is output.

Hereinafter, a method for determining whether the determination result of the magnetic pole determiner 9 ′, which is a function added to the magnetic pole determiner 9 ′, is success or failure will be described.
As described above, the principle of determination by the magnetic pole determiner 6 ′ uses the magnetic saturation phenomenon caused by the magnetizing action and demagnetizing action caused by the magnetic flux and permanent magnet magnetic flux caused by the flow of the γ-axis current iγ. Whether the phase difference Δθ is 180 degrees or 0 degrees based on the relationship between the inductance Ldp when flowing until the predetermined value (Ip) is reached and the inductance Ldn when flowing until the negative predetermined value (−Ip) is reached Is judged. However, as in the first embodiment, if the phase difference Δθ is not converged by the phase converging unit 5 ′ to 180 degrees or 0 degrees, the magnetic saturation phenomenon cannot be used and Ldp There is no difference in the relationship with Ldn, and it is impossible to determine whether the phase difference Δθ is 180 degrees or 0 degrees.
Therefore, if the absolute value of the difference between Ldp and Ldn does not exceed the predetermined value L, or the ratio between Ldp and Ldn does not exceed the predetermined value Y, the determination result is determined as failure.

  When the determination result of the magnetic pole determiner 9 ′ is determined to be unsuccessful, an arbitrary initial value of the phase of the γ-axis that is the input of the phase converging unit 8 ′ is shifted by a predetermined value, and the d-axis phase is estimated again. Thus, even if the difference between Ld and Lq is small, the phase of the d-axis output from the phase converging unit 8 ′ can be brought as close as possible to the phase difference Δθ = 180 degrees or 0 degrees, and the determination by the magnetic pole determination unit 9 ′ It is possible to estimate the phase of the d-axis by making the result successful.

In the description of the first embodiment and the second embodiment, the input voltage uses the detected value, but the same effect can be obtained even if the estimated value is used.

  According to the present invention, even if the difference between Ld and Lq is small, the phase of the d-axis of the permanent magnet synchronous motor at the time of stoppage can be accurately estimated, so that there is a great industrial applicability.

It is explanatory drawing which showed Example 1 of this invention. It is explanatory drawing which showed Example 2 of this invention. It is explanatory drawing which showed an example of the prior art. It is explanatory drawing which showed an example of the prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Power converter 2 Permanent magnet synchronous motor 3 Current detector 4 Voltage detector 5, 5 ', 8, 8' Phase converger 6, 6 ', 9, 9' Magnetic pole determination device 7 Switch

Claims (1)

When the permanent magnet synchronous motor is stopped, the phase (direction) of the N pole of the permanent magnet of the rotor of the permanent magnet synchronous motor is set as the d axis, and the estimated phase of the N pole of the permanent magnet is set as the γ axis. An arbitrary initial value of the phase of the γ-axis is input, and the phase of the γ-axis is gradually increased for a predetermined period so that the phase difference between the phase of the d-axis and the phase of the γ-axis converges to 0 degree or 180 degrees. Corrected and output phase converging device, input the output of the phase converging device, determine whether the phase difference is 0 degree or 180 degree, and if the phase difference is determined to be 0 degree, the phase converging A magnetic pole discriminator for adding 180 degrees to the output of the phase converging device and outputting the output when the output of the phase converging device is determined to be 180 degrees, and in the order of the phase converging device and the magnetic pole discriminating device. Initial phase estimation of a permanent magnet synchronous motor that operates to estimate the phase of the d-axis In the apparatus, the magnetic pole discriminator has a function of determining whether the judgment of the magnetic pole discriminator is successful or unsuccessful, and when the magnetic pole discriminator judges that it has failed, the initial value of the phase converging device is set to a predetermined value. An initial phase estimation device for a permanent magnet synchronous motor, wherein the phase of the d-axis is reestimated after being shifted.

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