JP5223109B2 - Control device for permanent magnet type synchronous motor - Google Patents

Description

  The present invention relates to a control device for a permanent magnet type synchronous motor, and more particularly to a technique for measuring the permanent magnet magnetic flux and inductance of a permanent magnet type synchronous motor with high accuracy.

  A permanent magnet type synchronous motor (hereinafter also referred to as PMSM) performs current control on d and q coordinates including a d axis (rotor magnetic pole direction) of a rotor and a q axis 90 degrees advanced from the d axis. Thus, highly accurate torque control can be realized. Here, the torque of PMSM is expressed by Equation 1.

  For this reason, in order to control the torque with high accuracy, it is desirable to accurately measure the permanent magnet magnetic flux and the inductance, and to control the current based on this. For this reason, based on the voltage equation model of PMSM, a technique for measuring permanent magnet magnetic flux and inductance from information on current, terminal voltage, and speed has been put into practical use.

  For example, in Non-Patent Document 1, when the current is controlled to zero by utilizing that the terminal voltage when the PMSM current is controlled to zero is equal to the induced voltage induced in the terminal by the permanent magnet magnetic flux. Describes a technique for measuring the permanent magnet flux by dividing the terminal voltage by the velocity. Furthermore, a technique for measuring the d-axis inductance and the q-axis inductance from the current, the terminal voltage and the speed using the voltage equation of PMSM is described.

Moreover, in the constant identification method of the synchronous motor described in Patent Document 1, “speed estimation value without adding a correction amount” obtained from the q-axis component of the induced voltage based on the q-axis voltage equation ((6) of Patent Document 1) So that the “estimated speed value with correction amount” calculated from the vector sum of the induced voltages based on the d and q-axis voltage equations (calculated by equation (7) in Patent Document 1) matches. The permanent magnet magnetic flux (induced voltage constant k _{e in} Patent Document 1) is calculated. Further, it is described that the d-axis inductance is calculated so that the q-axis induced voltage estimated value becomes a constant value even if the d-axis current is controlled to a different value (the above description is described in Patent Document 1). The description on the γ and δ axes (estimated axes of d and q axes) is replaced with d and q axes).

Japanese Patent No. 3707659 (Claim 1, Claim 3, Paragraphs [0006] to [0014], FIG. 1, FIG. 2, etc.) Shigeo Morimoto, Yoji Takeda, Tagao Hirata, “Measuring method of dq axis equivalent circuit constant of PM motor”, IEEJ Transactions D, Vol. 113, No. 11, p. 1330-1331, 1993

First, the first problem of the prior art will be described.
In order to measure the permanent magnet magnetic flux and the inductance by the methods described in Non-Patent Document 1 and Patent Document 1, it is necessary to operate the electric motor at a predetermined speed. For this reason, when the electric motor is coupled to the load, it is necessary to generate a load torque, and the q-axis current cannot always be controlled to zero. Here, since the embedded magnet structure permanent magnet type synchronous motor (hereinafter referred to as IPMSM) has different d-axis inductance and q-axis inductance depending on the saliency of the rotor, by actively controlling the d-axis current, In many cases, the torque / current is increased using the reluctance torque which is the second term on the right side of Formula 1. For this reason, when the load torque is large, the d-axis current may not be controlled to zero.

Hereinafter, problems of the related art according to Non-Patent Document 1 and Patent Document 1 during load operation will be described.
As described above, in Non-Patent Document 1, since it is necessary to control the current to zero in order to measure the permanent magnet magnetic flux, the permanent magnet magnetic flux cannot be measured during load operation. Further, since the value of the permanent magnet magnetic flux is necessary for measuring the d-axis inductance, it is impossible to measure the d-axis inductance during load operation.
Further, in Patent Document 1, since information on inductance is necessary to calculate the induced voltage under a condition where the current is not zero, the permanent magnet magnetic flux cannot be measured during load operation.

Next, the second problem of the prior art will be described.
In the measurement of the q-axis inductance according to Non-Patent Document 1, since the q-axis current needs to be controlled to a non-zero value, torque is generated during the measurement of the q-axis inductance, and the electric motor may be suddenly accelerated or decelerated.
Incidentally, the q-axis inductance is, for example, as shown in Japanese Patent Laid-Open No. 2000-50700, the current and the terminal voltage when an alternating current that alternates in the q-axis direction is passed while the rotor is stationary. It can be measured from the relationship. However, since the alternating current generally passes a high-frequency current, it may not be accurately measured due to the skin effect.

  Accordingly, the problem to be solved by the present invention is to provide a control device for a permanent magnet type synchronous motor that solves the above-mentioned various problems and can measure the permanent magnet magnetic flux and the inductance with high accuracy regardless of the load conditions. It is in.

In order to solve the above-mentioned problems, the invention according to claim 1 comprises an electrical constant measuring means for measuring the permanent magnet magnetic flux and the inductance of the motor from the detected current value, the detected terminal voltage value and the detected speed value of the permanent magnet type synchronous motor. In the control device of the permanent magnet type synchronous motor provided,
The electrical constant measuring means includes
Taking the terminal voltage and current of the motor as a vector,
Means for estimating the magnetic flux from the current detection value, terminal voltage detection value and speed detection value of the motor;
Means for controlling the d-axis current to a plurality of values when the magnetic pole direction of the rotor of the electric motor is the d-axis and the direction perpendicular thereto is the q-axis;
The relationship between the d-axis current controlled to a plurality of values and the estimated value of the magnetic flux corresponding to each of these d-axis currents is approximated by a linear function, and the d-axis inductance of the motor is measured from the slope of this linear function. And means for measuring the permanent magnet magnetic flux of the electric motor from the intercept of the linear function.
As a result, the permanent magnet magnetic flux and the d-axis inductance of the permanent magnet type synchronous motor can be accurately measured regardless of the load condition.

According to a second aspect of the present invention, in the control device according to the first aspect, the current detection is performed when an alternating current is passed through the motor or an alternating voltage is applied while the rotor is stopped. Second inductance measuring means for measuring the d-axis inductance and the q-axis inductance of the electric motor from the relationship between the value and the terminal voltage detection value;
Means for measuring the q-axis inductance of the motor from the d-axis inductance and the q-axis inductance measured by the second inductance measuring means and the d-axis inductance measured by the electrical constant measuring means. is there.
As a result, the q-axis inductance can be accurately measured without being affected by the skin effect.

  According to the present invention, the permanent magnet magnetic flux and inductance of the PMSM can be measured with high accuracy regardless of the load condition, and the torque control performance can be improved.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a control device according to this embodiment.
First, a method for controlling the PMSM speed to a command value will be described together with the configuration of the control device.

As described above, since PMSM can achieve high-precision control by performing current control on the d and q coordinates, the speed control described below is also performed on the d and q coordinates.
In FIG. 1, an input voltage detection circuit 12 detects an input voltage E _dc of a power converter 70 composed of an inverter or the like. The magnetic pole position detector 90 detects the magnetic pole position θ _{1 of the} PMSM 80, and the speed detection value 91 detects the speed ω ₁ of the PMSM 80.

A deviation between the speed command value ω ^* and the detected speed value ω ₁ is calculated by the subtractor 16, and this deviation is amplified by the speed regulator 17 to calculate the torque command value τ ^* .
Based on the torque command value τ ^* and the speed detection value ω ₁ , the current command calculation unit 18 maximizes the torque / current under the condition that the terminal voltage of the PMSM 80 is less than or equal to the maximum output voltage of the power converter 70 and D and q-axis current command values i _d0 ^* and i _q0 ^* are output.

Then added by the adder 32 i _dm ^* and which corresponds to the output of the d-axis current command value i _d0 ^* and the electric constant measurement current command generator 31 calculates the d-axis current command value i _d ^* . Here, i _dm ^* is controlled to two different values.
On the other hand, the q-axis current command value i _q ^* is set to the q-axis current command value i _q0 ^* output from the current command calculation unit 18.

The current coordinate converter 14 detects the phase current detection values i _u and i _w detected by the u-phase current detector 11u and the w-phase current detector 11w, respectively, based on the magnetic pole position detection value θ ₁ and detects the d and q-axis currents. Coordinates are converted to values i _d and i _q , respectively.
The deviation between the d-axis current command value i _d ^* and the d-axis current detection value i _d calculated by the subtractor 19a, the deviation is amplified by a d-axis current regulator 20a d axis voltage value v _d ^* Calculate. On the other hand, a deviation between the q-axis current command value i _d ^* and the q-axis current detection value i _q is calculated by the subtractor 19b, and this deviation is amplified by the q-axis current regulator 20b to be q-axis voltage command value v _q. ^* Is calculated.
These d and q axis voltage command values v _d ^* and v _q ^* are converted into phase voltage command values v _u ^* , v _v ^* , and v _w ^* by the voltage coordinate converter 15 based on the magnetic pole position detection value θ _1. The

The rectifier circuit 60 rectifies the three-phase AC voltage of the three-phase AC power source 50 to convert it into a DC voltage, and supplies this DC voltage to the power converter 70.
The PWM circuit 13 outputs the output voltage of the power converter 70 from the phase voltage command values v _u ^* , v _v ^* , v _w ^* and the input voltage E _dc of the power converter 70 detected by the input voltage detection circuit 12. _Is generated to control the phase voltage command values v _u ^* , v _v ^* , and v _w ^* . The power converter 70 controls the internal semiconductor switching element based on the gate signal, thereby controlling the terminal voltage of the PMSM 80 to the phase voltage command values v _u ^* , v _v ^* , v _w ^* .
With the above arithmetic processing, the speed of the PMSM 80 can be controlled to a command value.

Next, details of the electric constant measuring means 30 for measuring the permanent magnet magnetic flux and the inductance of the PMSM 80 will be described. FIG. 2 shows a block diagram of the electric constant measuring means 30.
In FIG. 2, the d-axis magnetic flux estimator 100 estimates the d-axis magnetic flux based on the PMSM q-axis voltage equation. The PMSM d and q-axis voltage equations are as shown in Equation 2.

Further, the d-axis magnetic flux Ψ _d is expressed by Equation 3.

From Equations 2 and 3, the d-axis magnetic flux estimator 100 calculates the d-axis magnetic flux estimated value ψ _dest by Equation 4.

Next, the parameter estimator 101 uses the fact that the d-axis magnetic flux Ψ _d is a linear function of the d-axis current i _d as shown in Equation 3, and controls the d-axis current _id to two different values. The permanent magnet magnetic flux and the d-axis inductance are calculated from the estimated d-axis magnetic flux Ψ _dest at that time. The operation of controlling the two different values of d-axis current i _d, the electric constant measurement current instruction generator 31 in FIG. 1, a i _dm ^* is realized by controlling the two different values.

FIG. 3 shows the operation principle of the parameter estimator 101. That is, in FIG. 3, when the d-axis magnetic flux estimation values when the d-axis current is controlled to I _d1 and I _d2 are Ψ _d1 and Ψ _d2 , respectively, the d-axis inductance is a linear function connecting two operating points. Equal to the slope. From this, the d-axis inductance L _dest is calculated by Equation 5.

  On the other hand, since the permanent magnet magnetic flux is equal to the intercept of the linear function, it is calculated by Equation 6.

  Through the above arithmetic processing, the permanent magnet magnetic flux and the d-axis inductance can be accurately measured even during load operation.

Next, a second embodiment of the present invention will be described. In this embodiment, the second d-axis inductance L is determined from the relationship between the detected current value and the terminal voltage when an alternating current is passed or the AC voltage is applied while the rotor is stationary. _{The dest} and the second q-axis inductance L _qest are measured, and the q-axis inductance is _obtained using these measured values and the first d-axis inductance L _dest measured according to the first embodiment.

The second d-axis inductance L _dest and the second q-axis inductance L _qhest may have errors due to the skin effect, but the ratio of both inductances (L _qhest / L _dhest ) can be accurately measured. On the other hand, the first d-axis inductance L _dest can be accurately measured by Equation 5 without being affected by the skin effect. For these reasons, according to the second embodiment, the q-axis inductance L _qest can be accurately measured by Equation 7 without being affected by the skin effect.

In the above-described embodiments, the case where the speed control is performed using the magnetic pole position detector 90 and the speed detector 91 as shown in FIG. 1 has been described. However, the control device according to the present invention detects these magnetic pole positions. The present invention can be similarly applied to so-called sensorless control in which speed control is performed by indirectly calculating the magnetic pole position and speed from the current and terminal voltage information of the PMSM80 without using a detector or speed detector. .
In each embodiment, the d-axis magnetic flux estimated value ψ _dest is directly calculated from the q-axis voltage equation of PMSM80, but may be calculated by a magnetic pole observer.

1 is a block diagram showing a first embodiment of the present invention. It is a block diagram of the electrical constant measurement means in FIG. It is a figure which shows the principle of operation of the parameter estimator in FIG.

Explanation of symbols

11u u-phase current detector 11w w-phase current detector 12 input voltage detection circuit 13 PWM circuit 14 current coordinate converter 15 voltage coordinate converter 16 subtractor 17 speed adjuster 18 current command calculation units 19a and 19b subtractor 20a d-axis Current regulator 20b q-axis current regulator 30 Electrical constant measuring means 31 Current command generator 32 for electrical constant measurement 32 Adder 50 Three-phase AC power supply 60 Rectifier circuit 70 Power converter 80 Permanent magnet synchronous motor (PMSM)
90 magnetic pole position detector 91 speed detector 100 d-axis magnetic flux estimator 101 parameter estimator

Claims (2)

In a control apparatus for a permanent magnet type synchronous motor provided with an electric constant measuring means for measuring a permanent magnet magnetic flux and an inductance of the electric motor from a detected current value, a detected terminal voltage value and a detected speed value of the permanent magnet type synchronous motor,
The electrical constant measuring means includes
Taking the terminal voltage and current of the motor as a vector,
Means for estimating the magnetic flux from the current detection value, terminal voltage detection value and speed detection value of the motor;
Means for controlling the d-axis current to a plurality of values when the magnetic pole direction of the rotor of the electric motor is the d-axis and the direction perpendicular thereto is the q-axis;
The relationship between the d-axis current controlled to a plurality of values and the estimated value of the magnetic flux corresponding to each of these d-axis currents is approximated by a linear function, and the d-axis inductance of the motor is measured from the slope of this linear function. And means for measuring the permanent magnet magnetic flux of the electric motor from the intercept of the linear function;
A control device for a permanent magnet type synchronous motor. In the control device for the permanent magnet type synchronous motor according to claim 1,
From the relationship between the detected current value and the detected terminal voltage when an alternating current is passed through the motor while the rotor is stopped, or when an alternating voltage is applied, the d-axis inductance of the motor and second inductance measuring means for measuring q-axis inductance;
Means for measuring the q-axis inductance of the motor from the d-axis inductance and the q-axis inductance measured by the second inductance measuring means, and the d-axis inductance measured by the electrical constant measuring means;
A control device for a permanent magnet type synchronous motor.

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