JP2001069777A - Device for estimating position and speed of synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the direction of a permanent magnet and the rotational speed of a synchronous motor estimatable even under a wide range of conditions by estimating the direction of the magnet and correcting the estimated rotational speed of the motor by means of a position and speed estimating means. SOLUTION: A speed estimating means 20 incorporated in a position and speed estimating means 10 estimates the rotational speed ωm1 of a synchronous motor by inputting a d-axis current id, a q-axis current iq, and a q-axis voltage vg and a positional error estimating means 21 outputs the error in the estimated direction θg of a permanent magnet. Then a speed error estimating device 22 outputs the rotational speed error corresponding to the error in the direction θg of the permanent magnet and an adder 23 calculates the sum of the output of the speed error estimating device 22 and the output gh of a speed error detector and outputs the sum ωm2 of the rotational speed errors corresponding to the errors in the direction θg of the permanent magnet. In addition, another adder 26 outputs the sum ωmx of the output ÷m1 of the speed estimating means 20 and the output ωm2 of the adder 23 and an integrator 27 integrates the sum ωmx. Then the position and speed estimating means 10 outputs the integrated result as the direction θg. Therefore, the rotational speed of a synchronous motor and the direction of the permanent magnet can be estimated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for controlling a permanent magnet type synchronous motor, and more particularly to estimating the direction and rotational speed of a permanent magnet in a wide speed range without using a position sensor or a speed sensor. And an apparatus for estimating the position and speed of a synchronous motor.

[0002]

2. Description of the Related Art FIG. 3 is a block diagram showing an example of the entire structure of a conventional technique, and FIG. 4 is a detailed view of a position correcting means shown in FIG. 3, reference numeral 1 denotes a permanent magnet type synchronous motor, 4 denotes a power converter for supplying electric power to the permanent magnet type synchronous motor 1, 6
Is a high-frequency current superimposer that outputs a signal such that a high-frequency current is superimposed on the d-axis current id, 2 is a voltage detector that detects a primary voltage v1 applied to the permanent magnet type synchronous motor 1,
Is a current detector for detecting a primary current i1 flowing through the permanent magnet type synchronous motor 1.

[0003] Reference numeral 7 denotes a voltage component converter for inputting the primary voltage v1 and the estimated direction of the permanent magnet to output a d-axis voltage vd and a q-axis voltage vq, and 8 denotes a permanent magnet estimated as a primary current i1. And input the d-axis current id and the q-axis current iq
And a current component converter that outputs

Reference numeral 9 denotes a position correcting means for inputting the d-axis current id, the q-axis current iq, and the q-axis voltage vq to output an estimated error in the direction of the permanent magnet or an error equivalent Δθf, and 28 denotes a position correcting means. 9 is a proportional-integral amplifier for estimating the rotational speed ωg of the permanent magnet synchronous motor 1 by inputting the output of 9, and an integrator 29 for integrating the rotational speed ωg to estimate the direction θg of the permanent magnet.

In FIG. 4, reference numeral 12 in the position correcting means 9 denotes a differentiator for differentiating the q-axis current iq. Reference numeral 13 denotes an inductance voltage drop calculator that outputs the product of the output of the differentiator 12 and the q-axis inductance Lq of the permanent magnet type synchronous motor 1. A resistance voltage drop calculator 14 outputs the product of the q-axis current iq and the armature resistance R of the permanent magnet type synchronous motor 1. An adder 15 outputs the sum of the output of the inductance voltage drop calculator 13 and the output of the resistance voltage drop calculator 14. 16 is a subtractor, which is a q-axis voltage vq
And the output of the adder 15 is output.

Reference numeral 17 denotes a differentiator for differentiating the output of the subtractor 16. Reference numeral 18 denotes a position error detector, which outputs the output of the differentiator 17 and d
A product Δθh with the shaft current id is output. Reference numeral 19 denotes a low-pass filter which removes harmonic components of the output of the position error detector 18 and outputs a DC component Δθf.

Next, the synchronous motor position and speed estimating apparatus having such a configuration will be described in detail below, taking into account the circumstances leading to the invention of the present invention. FIG. 5 shows the relationship between the actual permanent magnet direction θgr of the permanent magnet type synchronous motor and the estimated permanent magnet direction θg as a vector.

[0008]

(Equation 1)

Assume that there is a position error Δθ. When a high-frequency current is superimposed on the d-axis current id by the high-frequency current superimposer 6, the d-axis current id and the q-axis current iq are represented by the following equations.

[0010]

(Equation 2)

Here, Id and Iq are DC components, I is the peak value of the high-frequency current, ωh is the angular frequency of the high-frequency current, and t is time. In the primary current i1, a dr-axis current idr in a direction parallel to the actual direction θgr of the permanent magnet (hereinafter, referred to as dr axis) and a qr-axis current iqr in an axis perpendicular to the dr axis (hereinafter, referred to as qr axis) are: From the d-axis current id and q-axis current iq in equations (2) and (3),

[0012]

(Equation 3)

## EQU1 ##

The characteristic equation of the permanent magnet type synchronous motor 1 is expressed by the following equation.

[0015]

(Equation 4)

Here, vdr is the dr-axis voltage, and vqr is q
r-axis voltage, Ld is the d-axis inductance of the permanent magnet type synchronous motor 1, p is the differential operator, φ is the magnetic flux of the permanent magnet, ωg
r is the actual rotation speed of the permanent magnet synchronous motor 1.
Next, when equations (4) and (5) are substituted into equations (6) and (7),

[0017]

(Equation 5)

## EQU1 ## Therefore, the estimated q-axis voltage vq of the component perpendicular to the direction θg of the permanent magnet is expressed by Expression (10) from Expressions (8) and (9).

[0019]

(Equation 6)

The product Δθh of the d-axis current id output from the position error detector 18 and the value dvq obtained by differentiating the q-axis voltage vq is given by the following equations (2) and (10).

[0021]

(Equation 7)

## EQU1 ## Although the q-axis current iq is controlled to the DC component Iq as shown in the equation (3), the d-axis current id is actually changed to the harmonic current as shown in the equation (2) by interference between the d-axis and the q-axis. Is controlled so that the q-axis current iq
Also, harmonic components appear. The harmonic component of the q-axis current iq also appears in the q-axis voltage vq. Therefore, in FIG. 4, in order to remove the influence of the harmonic component of the q-axis current iq appearing in the q-axis voltage vq, the q-axis voltage v
The second term relating to the qr-axis current iqr in equation (7) is removed from q. When Δθh is passed through the low-pass filter 19 to remove harmonic components, the following equation (12) is obtained.

[0023]

(Equation 8)

Here, assuming that the position error Δθ is very small, the DC component Δθf of the equation (12) can be approximated by the equation (13).

[0025]

(Equation 9)

Here, K1 is

[0027]

(Equation 10)

Is as follows. Since Lq> Ld, equation (13) shows that the position error Δθ and the DC component Δθf are in a proportional relationship. That is, the estimated direction of the permanent magnet θg
Is more advanced than the actual permanent magnet direction θgr,
Δθf <0, and the estimated rotational speed ωg of the permanent magnet type synchronous motor 1 is reduced by the proportional-integral amplifier 28, so that the estimated advance of the direction θg of the permanent magnet is slowed down,
The direction coincides with the actual direction θgr of the permanent magnet. The same applies to the opposite case. That is, by multiplying the d-axis current id by the value obtained by differentiating the q-axis voltage vq, Δθf corresponding to the position error Δθ is obtained, so that the direction θg and the rotational speed ωg of the permanent magnet can be estimated. In view of the above, the following describes the issues that have been taken as conventional issues.

[0029]

The conventional method is effective when the permanent magnet type synchronous motor is stopped or rotating at a low speed. However, as can be seen from the characteristic equation (7) of the permanent magnet type synchronous motor 1, the higher the rotation speed, the higher the voltage. When the voltage exceeds the voltage that can be supplied by the power converter 4, there is a problem that the high-frequency current cannot be superimposed on the d-axis current id, and the direction θg and the rotation speed ωg of the permanent magnet cannot be estimated.

Similarly, when the rotational speed of the permanent magnet type synchronous motor suddenly changes, the dr-axis current idr and q
The r-axis current iqr increases, and d is obtained from the equations (6) and (7).
The r-axis voltage vdr and the qr-axis voltage vqr increase, and the direction θg and rotation speed ωg of the permanent magnet cannot be estimated. The present invention has been made in view of the above points, and aims to solve these disadvantages, and to estimate the direction and rotation speed of the permanent magnet by high-speed rotation, etc. And an apparatus for estimating the position and speed of the synchronous motor which can estimate the direction and rotation speed of the motor.

[0031]

Means for attaining the object are as follows: 1) The primary current parallel to the estimated permanent magnet direction (d-axis) of the permanent magnet type synchronous motor according to claim 1. A synchronous motor having position correcting means for superposing a high-frequency current on the d-axis current which is a component of the above, and correcting the estimated direction of the permanent magnet from the detected primary current and primary voltage of the permanent magnet type synchronous motor. A position and speed estimating device, a speed estimating means for estimating the rotation speed of the permanent magnet type synchronous motor from the primary current and the primary voltage, and the permanent magnet estimated from the primary current and the primary voltage A position error estimating means for estimating a direction error; and an arithmetic means for adding the output of the position error estimating means and the output of the position correcting means, and adding this output and the output of the speed estimating means. The position and speed of the synchronous motor, wherein the position and speed estimation means estimates the direction of the permanent magnet and corrects the estimated rotation speed. It is an estimation device.

2) The rotational speed of the permanent magnet type synchronous motor according to claim 2, wherein the speed estimating means determines the rotational speed of the permanent magnet type synchronous motor from the d-axis current, the q-axis current in the direction perpendicular to the d-axis (q-axis), and the q-axis voltage. 2. The synchronous motor according to claim 1, wherein the position error estimating unit estimates an error in the estimated direction of the permanent magnet from the d-axis current, the q-axis current, and the d-axis voltage. Is a position and velocity estimating device.

[0033] In the third aspect, the calculating means obtains a rotation speed error corresponding to the estimated error of the direction of the permanent magnet from the output of the position error estimating means and the output of the position correcting means. The synchronous motor according to claim 1, wherein the speed error is passed through a low-pass filter, and the estimated rotational speed is corrected from an output of the low-pass filter and an output of the speed estimating means. It is a speed estimation device.

(4) In the above (4), when the high-frequency current and the output of the position correcting means exceed a certain arbitrary rotation speed, the output is reduced to zero at an arbitrary slope and becomes zero. 2. The method according to claim 1, wherein the slope is increased to the original value when the slope is equal to or less than a predetermined value, and a slope of the high-frequency current is smaller than a slope of an output of the position correcting unit.
It is a position and speed estimation device of the synchronous motor described in the above. Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram of the overall configuration showing an embodiment of the present invention, and FIG. 2 is a block diagram showing an embodiment of the position / speed estimating means of FIG. Elements having the same reference numerals as 3 have the same configuration and function, and therefore description thereof is omitted. In FIG. 1, a speed error detector 11
Outputs the error of the rotational speed estimated by inputting the DC component Δθf which is the output of the position correcting means 9 up to an arbitrary rotational speed, and when the rotational speed exceeds the arbitrary rotational speed, the rotational speed becomes zero. The output is reduced at an arbitrary inclination until the rotation speed becomes equal to or less than the rotation speed when the output becomes zero, and a value increased to the original value at the arbitrary inclination is output. position·
The speed estimating means 10 outputs the output ωgh of the speed error detector 11.
And the d-axis current id, the q-axis current iq, the d-axis voltage vd, and the q-axis voltage vq, and outputs the estimated permanent magnet direction θg and the rotational speed ωg of the permanent magnet type synchronous motor 1.

The high-frequency current superimposer 5 is different from the high-frequency current superimposer 6 shown in FIG. 3 in that it outputs a signal such that a high-frequency current is superimposed on a d-axis current id up to a certain rotation speed. When the rotation speed is exceeded, the output is reduced at an arbitrary slope until the rotation becomes zero, and when the rotation speed becomes equal to or less than the rotation speed when the rotation becomes zero, the output is increased to the output of the original value at the arbitrary slope. The point is that the inclination is smaller than an arbitrary inclination of the error detector 11.

In FIG. 2, the speed estimating means 20 in the position / speed estimating means 10 receives the d-axis current id, the q-axis current iq, and the q-axis voltage vq, and outputs the rotation speed of the permanent magnet type synchronous motor 1. ωm1 is estimated. The position error estimating means 21 calculates d
The axis current id, the q-axis current iq, and the d-axis voltage vd are input, and the estimated error of the permanent magnet direction θg is output.
The speed error estimator 22 receives the output of the position error estimating means 21 and outputs a rotation speed error corresponding to the estimated error in the direction θg of the permanent magnet.

The adder 23 calculates the sum of the output of the speed error estimator 22 and the output ωgh of the speed error detector 11, and calculates the sum ωm2 of the rotational speed error according to the estimated error in the direction θg of the permanent magnet. Output. The low-pass filter 24 removes the harmonic component of the output ωm2 of the adder 23 and removes the DC component dt
Output h. The adder 25 outputs the output ω of the speed estimating means 20.
The sum of m1 and the output dth of the low-pass filter 24 is calculated, and the estimated rotational speed ωg of the permanent magnet type synchronous motor 1 is calculated.
Output as In this way, the calculating means is the adder 2
3, 25, etc.

The adder 26 outputs the sum ωmx of the output ωm1 of the speed estimating means 20 and the output ωm2 of the adder 23. The integrator 27 outputs the integration of the output ωmx of the adder 23 as the estimated permanent magnet position / velocity estimating means 10 middle direction θg.

The reason why the above problems can be solved by claims 1, 2, and 3 of the present invention will be described below. When the characteristic equation (7) of the above-described permanent magnet type synchronous motor 1 is solved for the rotation speed ωgr, the following is obtained.

[0041]

[Equation 11]

Is as follows. Therefore, when the dr-axis current idr of the equation (15) is set to the d-axis current id, the qr-axis current iqr is set to the q-axis current iq, and the qr-axis voltage vqr is set to the q-axis voltage vq, the rotation speed ωg can be estimated. .

The voltage equation of the d-axis voltage vd when there is a position error Δθ is expressed by equation (16).

[0044]

(Equation 12)

When equation (16) is solved for sin (Δθ), the following equation (17) is obtained.

[0046]

(Equation 13)

Assuming that the position error Δθ is very small, the position error Δθ can be approximated by equation (18).

[0048]

[Equation 14]

By differentiating the position error Δθ in the speed error estimator 22, a rotational speed error corresponding to the position error Δθ can be obtained. The speed error detector 11 also differentiates the position error Δθ represented by the equation (9), and obtains a rotation speed error corresponding to the position error Δθ. Therefore, the sum of the output of the speed error estimator 22 output from the adder 23 and the speed error detector 11 determines the rotational speed error ωm corresponding to the position error Δθ.
2 can be output. The reason why the output ωm2 of the adder 23 is added to the rotation speed ωm1 estimated after passing through the low-pass filter 24 is to remove noise of the output ωm2 of the adder 23. As described above, if the d-axis current id, the q-axis current iq, the d-axis voltage vd, and the q-axis voltage vq are known, the equations (15) and (16) can be used even if the voltage exceeds the voltage that can be supplied by the power converter 4. The rotational speed ωg of the permanent magnet type synchronous motor 1 and the direction θg of the permanent magnet can be estimated using the equations.

Next, claim 4 will be described. Since the position correcting means 9 of the conventional method becomes unnecessary if the permanent magnet type synchronous motor 1 rotates to some extent, when the rotation speed exceeds an arbitrary rotation speed, the high frequency current and the output of the speed error detector 11 are reduced to zero. At this time, the direction of the permanent magnet and the rotational speed cannot be estimated unless the position correcting means 9 superimposes the high-frequency current on the d-axis current id. Therefore, the inclination of the high-frequency current is reduced and the output of the speed error detector 11 is reduced. Be able to superimpose earlier than it is used.

[0051]

As described above, according to the present invention, since the rotation speed and the direction of the permanent magnet of the permanent magnet type synchronous motor can be estimated in a wide range, a position sensor and a speed sensor are not required, and practically, It is extremely useful.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram of a position / velocity estimating means showing one embodiment of the present invention.

FIG. 3 is a block diagram showing an example of a conventional system.

FIG. 4 is a block diagram of a position correcting means showing an example of a conventional method.

FIG. 5 is a vector diagram for explaining the principle of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Permanent magnet type synchronous motor 2 Voltage detector 3 Current detector 4 Power converter 5 High frequency current superposition device 6 High frequency current superposition device 7 Voltage component converter 8 Current component converter 9 Position correction means 10 Position / speed estimation means 11 Speed Error detector 12 Differentiator 13 Inductance voltage drop calculator 14 Resistance voltage drop calculator 15 Adder 16 Subtractor 17 Differentiator 18 Position error detector 19 Low-pass filter 20 Speed estimating means 21 Position error estimating means 22 Speed Error estimator 23 adder 24 low-pass filter 25 adder 26 adder 27 integrator 28 proportional-integral amplifier 29 integrator

Continued on the front page F term (reference) 2F063 AA35 BA30 DA05 GA01 GA32 GA36 5H560 BB12 DA12 DB12 DC12 DC13 EB01 EB02 RR10 TT08 TT20 XA13 5H576 BB10 DD07 EE01 HB01 HB04 JJ04 JJ22 JJ23 JJ24 JJ24 LL14

Claims (4)

[Claims] 1. A permanent magnet type synchronous motor in which a high-frequency current is superimposed on a d-axis current which is a primary current component parallel to an estimated permanent magnet direction (d-axis) of a permanent magnet type synchronous motor and detected. In a position and speed estimating device for a synchronous motor having a position correcting means for correcting the estimated direction of the permanent magnet from the primary current and the primary voltage of the motor, the position and the speed of the permanent magnet type synchronous motor are determined from the primary current and the primary voltage. Speed estimating means for estimating a rotational speed, position error estimating means for estimating the estimated error of the direction of the permanent magnet from the primary current and primary voltage, and an output of the position error estimating means and the position correcting means. A position / speed estimating means composed of arithmetic means for adding an output and adding the output and the output of the speed estimating means;
An apparatus for estimating the position and speed of a synchronous motor, comprising estimating the direction of the permanent magnet and correcting the estimated rotational speed. 2. The speed estimating means estimates a rotation speed of the permanent magnet type synchronous motor from the d-axis current, a q-axis current in a direction perpendicular to the d-axis (q-axis), and a q-axis voltage. 2. The position and speed estimation of a synchronous motor according to claim 1, wherein the position error estimating means estimates the estimated error in the direction of the permanent magnet from the d-axis current, the q-axis current, and the d-axis voltage. apparatus. 3. An arithmetic unit determines a rotational speed error corresponding to the estimated error in the direction of the permanent magnet from an output of the position error estimating unit and an output of the position correcting unit. 2. The position and speed estimating device for a synchronous motor according to claim 1, wherein the estimated rotational speed is corrected through an output of the low-pass filter and an output of the speed estimating means through a pass filter. 4. The high-frequency current and the output of the position correcting means are reduced to zero at an arbitrary slope when the rotation speed exceeds a certain arbitrary rotation speed, and when the rotation speed becomes equal to or less than the rotation speed at the time when the rotation speed becomes zero. 2. The position and speed estimating device for a synchronous motor according to claim 1, wherein the gradient of the high frequency current is increased to the original value, and the gradient of the high frequency current is smaller than the gradient of the output of the position correcting means.