JP2013042631A - Control device of permanent magnet synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable identification of an off-set value of current detecting means to remove it, by speedily identifying motor constants while driving a motor.SOLUTION: The control device includes: a current simulator 9 for calculating d-axis and q-axis estimated currents with a motor speed, and a d-axis and q-axis voltages used as inputs; and identifying means 10 for identifying a self-inductance by controlling the motor at a constant speed so that a d-axis detected current becomes zero to adjust a self-inductance nominal value of the simulator 9 from the d-axis and q-axis estimated currents and d-axis and q-axis detected currents so that deviation of the number of flux interlinkage becomes zero, identifying an armature resistance by controlling the motor so that the d-axis detected current becomes a prescribed value to adjust the armature resistance nominal value of the simulator 9 from the d-axis and q-axis estimated currents and the d-axis and q-axis detected currents so that deviation of the number of flux interlinkage becomes zero, identifying the number of flux interlinkage from the d-axis and q-axis estimated currents and the d-axis and q-axis detected currents, and identifying an off-set value of current detecting means from the deviation between the d-axis estimated current and the d-axis detected current, and the deviation between the q-axis estimated current and the q-axis detected current.

Description

  The present invention relates to a control device for a permanent magnet synchronous motor, and more particularly to a technique for identifying motor constants such as motor self-inductance and armature resistance, and an offset adjustment technique for current detection means.

The synchronous motor can improve controllability and efficiency by appropriately detecting and controlling the current according to the position of the rotor. In this case, motor constants such as self-inductance, armature resistance, and flux linkage are required.
Generally, a design value is used for the motor constant of the synchronous motor, but there is an error between the actual value and the design value. Such errors greatly affect torque control accuracy and responsiveness. Since the motor constant fluctuates due to a temperature change or the like, it is desirable to adjust the motor constant used for control while sequentially identifying the motor during driving.

In addition, when detecting the current of the motor, a current sensor that requires electrical insulation is used, and as a detection element in that case, the strength of the magnetic field generated through the core having a gap is converted into a voltage. In general, the current detection signal is extracted by a Hall element.
However, the Hall element has an inherent offset due to component differences, individual differences, and the like, and this offset further has a characteristic that changes due to environmental factors such as sensitivity variations and temperature changes.

Here, as a method of measuring the motor constant of the synchronous motor, a method as shown in Patent Document 1 is known.
In the prior art according to Patent Document 1, the rotor is set to a stopped state, the q-axis current command and the d-axis current command are set to the first q-axis current command value and the first d-axis current command value, A d-axis current step command having a predetermined magnitude is given to the control device. A voltage value obtained by subtracting the voltage drop due to the primary resistance of the motor from the d-axis voltage command value generated corresponding to the deviation of the detected d-axis current value with respect to the step command is set to a predetermined first value. integral to over integration time to produce an integrated value v _dsum, it generates a variation .DELTA.i _d of d-axis current detection value at the time of integration end with respect to the d-axis current detection value of the integration start point.
The same calculation is performed for the q-axis to generate the integral values v _qsum and Δi _q , whereby the ratio of the d-axis inductance to the q-axis inductance: K = (v _qsum / v _dsum ) · (Δi _d / Δi _q ) is calculated. Then, by using the known d-axis inductance L _d and calculating the q-axis inductance L _q by L _q = KL _d , the identification is completed.

On the other hand, as a method for adjusting the offset of the current detector while measuring the motor constant during driving of the permanent magnet synchronous motor, there is a method as shown in Non-Patent Document 1.
In the prior art described in Non-Patent Document 1, a current simulator that simulates the electrical characteristics of a motor is configured, and the nominal value R _{n of} electrical parameters (armature resistance, self-inductance as a motor constant) used in the simulator. , L _n and error rates α and β between true values R _a and L _a , respectively. Then, with the d-axis current controlled to 0, the nominal value L _n is adjusted so that the value of the d-axis estimated current i _d ^ of the current simulator becomes 0, and the current ripple that appears as the offset of the detector is The error rate α is obtained from the current ratio between the removed q-axis estimated current i _q ^ and the q-axis detection current i _qsense, and the armature resistance _Ra is identified from the obtained error rate α. Further, determine the error rate β armature resistance R _a determined from the current ratio in the case of adjusting the parameters of the current simulator as nominal value R _n, to identify self-inductance value L _a from the error rate β obtained.
Then, to calculate the identified value R _a, the L _a as the electrical parameters of the current simulator, d-axis current, q-axis current and the current detector based on the electrical angle theta _re of the motor offset value .DELTA.i u _^, the .DELTA.i v _^ Is.

Japanese Unexamined Patent Publication No. 2001-352800 (paragraphs [0044] to [0056], FIG. 1, FIG. 2, etc.)

Sazawa, Kawagoe, Uenaka, Oishi, "Estimation method of current detection error and parameter fluctuation of permanent magnet motor using current simulator", IEEJ Industrial Application Division Journal, Vol.130, No.8, pp.100-1007 , August 2010

In the prior art disclosed in Patent Document 1, since a known d-axis inductance is used and an AC q-axis current command is input to the current controller after setting the rotor to a stopped state, the motor It is difficult to perform so-called on-line identification in which constant identification is performed during normal driving, and there are problems such as an offset of the current detector affecting the identification value and generating torque ripple.
On the other hand, according to the prior art disclosed in Non-Patent Document 1, if a constant current section is provided on the dq axis, the identification of the armature resistance _Ra and the self-inductance L, and the current detector However, there is a problem that the flux linkage number φ, which is one of the motor constants, cannot be identified.

  Therefore, the present invention controls a permanent magnet synchronous motor that quickly identifies various motor constants related to the d-axis and q-axis while driving the motor, and at the same time identifies the offset component of the current detection means and makes it adjustable. It is an object to provide an apparatus.

In order to solve the above-described problem, the invention according to claim 1 is directed to a current control unit that calculates a voltage command corresponding to a deviation between a current command of a permanent magnet synchronous motor and a detected current, and an AC voltage generated according to the voltage command. A control apparatus for a permanent magnet synchronous motor, comprising: a power converter that supplies the motor; and a current detection unit that converts the phase current as the detection current into a d-axis current and a q-axis current on dq rotation coordinates. In
A current simulator for calculating a d-axis and q-axis estimated current from the state equation of the motor by inputting the rotation speed of the motor and the d-axis and q-axis voltages on the dq rotation coordinates;
With the motor controlled at a constant speed such that the d-axis detection current of the motor becomes zero, the motor, the current simulator, The function of identifying the self-inductance of the motor by adjusting the self-inductance nominal value of the current simulator so that the deviation of the number of flux linkages of the motor becomes zero, and the d-axis detection current of the motor controlled to a predetermined value Using the d-axis and q-axis estimated currents and the d-axis and q-axis detection currents, the armature resistance nominal value of the current simulator is set so that the deviation of the number of flux linkages between the motor and the current simulator becomes zero. A function of adjusting and identifying the armature resistance of the motor, a function of identifying the number of flux linkages of the motor using the d-axis and q-axis estimated currents and the d-axis and q-axis detection currents, and the d And an identification unit having a function of identifying an offset value of the current detection unit based on a deviation between the estimated current and the d-axis detection current and a deviation between the q-axis estimation current and the q-axis detection current. .

In the present invention, the error of the flux linkage number is obtained from the d-axis and q-axis estimated currents and the d-axis and q-axis detected currents, which are the outputs of the current simulator in a state where the d-axis current is controlled to be zero. Identify self-inductance. Also, the error of the flux linkage is calculated from the d-axis, q-axis estimated current and the d-axis, q-axis detected current in the state where the self-inductance of the current simulator is set to the identified value and the d-axis current is controlled to an arbitrary value. Find the armature resistance. Then, the magnetic flux linkage number is identified by obtaining the error of the flux linkage number with the identified values of the self-inductance and the armature resistance of the current simulator. Thereby, all the motor constants can be identified while driving the synchronous motor.
Furthermore, according to the present invention, it is also possible to estimate the offset component from the d-axis and q-axis estimated currents and the d-axis and q-axis detected currents to obtain the offset value of the current detecting means.
That is, according to the present invention, various motor constants of the synchronous motor and the offset value of the current detecting means can be appropriately adjusted, and a highly accurate and highly responsive current control system is realized by suppressing the torque pulsation of the synchronous motor. It becomes possible to do.

It is a block diagram which shows the structure of embodiment of this invention. It is a flowchart which shows operation | movement of embodiment of this invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing the configuration of the present embodiment. In FIG. 1, a control device for a permanent magnet synchronous motor 1 according to this embodiment includes a power converter 2, a current detection means 3, a biaxial current conversion means 4, a speed detection means 5 such as an encoder, a rotation speed control means 6, In addition to d-axis current control means 7, q-axis current control means 8, and addition / subtraction means 11, 12d, 12q, 13u, 13v, a current simulator 9 and identification means 10 are provided.

Here, the power converter 2 includes a PWM inverter that outputs a three-phase AC voltage based on the d-axis voltage command v _d ^ref and the q-axis voltage command v _q ^ref , and is a power semiconductor switching element such as an IGBT. A three-phase switching circuit using is provided.
Each means other than the power converter 2 is realized by a control application of a DSP or a microcomputer, for example. The DSP or microcomputer may include a current detection core, peripheral devices such as a memory, an A / D conversion circuit, and a communication port. Of course, a part of each means other than the power converter 2 may be configured by a logic circuit.
As the permanent magnet synchronous motor 1 to be controlled, a surface magnet synchronous motor (SPM) is particularly assumed. Although this SPM has a lower torque than an embedded magnet synchronous motor (IPMSM), it has the advantage of a low torque ripple, so it is widely used in servo motors for positioning applications with high accuracy and high performance.

Next, based on FIG. 1, the outline | summary of the operation | movement at the time of the drive of the synchronous motor 1 is demonstrated.
The difference between the rotational speed omega _rm of the motor 1 detected by the target rotational speed omega _rm ^ref and the speed detecting means 5 provided externally determined by subtraction unit 11, on the basis of the deviation, the speed control means 6 q-axis current command i _q ^ref is generated.
The current detecting unit 3, u-phase and v-phase phase current i _u obtained by the current _detector, the i _v, and w-phase current i _w calculated from those, on the d-q coordinate by 2-axis current converter 4 The detection currents i _d ^sense and i _q ^sense are converted to In FIG 1, consider the offset value .DELTA.i _u, .DELTA.i _v is present in the current detector, subtraction means 13u, phase currents _i u by 13v, the _{i v} offset value .DELTA.i _u, .DELTA.i _v were respectively added The value is displayed so as to be input to the biaxial current converting means 4.

The detected currents i _d ^sense and i _q ^sense output from the biaxial current conversion unit 4, the arbitrarily set d axis current command i _d ^ref, and the q axis current command i _q ^ref output from the speed control unit 6 Deviations are respectively obtained by the addition / subtraction means 12d and 12q, and based on these deviations, the d-axis current control means 7 and the q-axis current control means 8 generate the d-axis voltage command v _d ^ref and the q-axis voltage command v _q ^ref , respectively. .
The d-axis voltage command v _d ^ref and the q-axis voltage command v _q ^ref are input to the power converter 2, and the three-phase AC voltage generated by the power converter 2 is supplied to the synchronous motor 1.
Through the series of operations described above, the synchronous motor 1 is controlled such that the actual rotational speed ω _rm follows the target rotational speed ω _rm ^ref . Note that the configuration and operation of the two-axis current conversion unit 4 and the reverse conversion unit (not shown) for converting the dq-axis voltage component into the three-phase voltage in the power converter 2 are well-known techniques, and thus description thereof is omitted. To do.

Next, the current simulator 9 that estimates the d-axis and q-axis currents will be described.
Based on the state equation on the dq coordinate axes of the synchronous motor 1, the current simulator 9 is realized by executing the calculation of Equation 1. In Equation 1, i _d ^ and i _q ^ are d-axis estimated current and q-axis estimated current, v _d and v _q are d-axis voltage and q-axis voltage, R _n is a nominal value of armature resistance of the motor 1, L _n is a nominal value of self-inductance, φ _fn is a nominal value of the number of flux linkages, and ω _re is an electrical angular frequency of the synchronous motor 1.
As is clear from Equation 1, the current simulator 9 receives v _d , v _q and ω _re as inputs, and further uses the nominal values R _n , L _n and φ _fn to determine the d-axis estimated current i _d ^ and the q-axis. The estimated current i _q ^ is output. In FIG. 1, voltage commands v _d ^ref and v _q ^ref are used as v _d and v _q in Equation 1, and ω _re in Equation 1 corresponds to the actual rotational speed ω _rm in FIG.

Next, the identification unit 10 will be described.
The identification means 10 is supplied with the d-axis estimated current i _d ^, the q-axis estimated current i _q ^ and the detected currents i _d ^sense and i _q ^{sense which} are the outputs of the current simulator 9. identifying a motor constant R _a, L _a, with identifying phi _f, offset value .DELTA.i u included in the current detection value of the current detection means _3, the .DELTA.i _v using the input.

Here, regarding the theoretical reason for parameter identification of the synchronous motor 1 in the identification means 10, first, the relationship between the offset of the current detection means 3 and the current simulator 9 will be described.
When an offset is added to the current detection value by the current detection means 3, the current control system performs control so as to suppress the current ripple due to the offset, so the voltage commands v _d ^ref and v _q ^ref include the effect of the offset. Therefore, the current simulator 9 in consideration of the current control system is expressed by Equation 2. In Equation 2, i _d ^ ′ and i _q ^ ′ are d-axis and q-axis estimated currents taking into account the current control system, R _a is an armature resistance value, L _a is a self-inductance value, Δi _d and Δi _q are is the actual d-axis d-axis, the q-axis estimated current, q-axis detection current _i d, the deviation between the _{i q (i q Δi d =} i d ^ '- - i d, Δi q = i q ^') . The d-axis and q-axis currents i _d and i _q correspond to the above-described i _d ^sense and i _q ^sense .

When the fluctuation rate of the armature resistance of the current simulator 9 with respect to the electric parameters of the synchronous motor is γ _a , the fluctuation rate of the self-inductance is γ _L , and the error of the number of flux linkages is Δφ i _d ^ ′ and the q-axis estimated current i _q ′ are given by Equation 4. According to Equation 4, the influence of the offset of the current detection means 3, that is, the term including Δi _d and Δi _q is the same for both the d-axis estimated current i _d ^ ′ and the q-axis estimated current i _q ′. It appears only in the second and third terms.

Usually, the offset of the current detection means is dominant DC component, the .DELTA.i _d and .DELTA.i _q on d-q-axis appears as an AC component. Accordingly, for both the d-axis estimated current i _d ^ ′ and the q-axis estimated current i _q ′, only the first term of Equation 4 appears in the DC component. By using the components, it is possible to realize an identification method that is insensitive to the offset of the current detection means.

Next, the theoretical reason for identifying the electric parameters of the motor will be described.
Of the electrical parameters, if only the flux linkage number φ _fa changes (that is, R _a = R _n , L _a = L _n ), the d-axis estimated current i _d ^ and the q-axis estimated current i _q ^ It can be expressed by Equation 5, and this can be expressed as Equation 6 by solving Δφ on the d-axis side as Δφ _d and Δφ on the q-axis side as Δφ _q for the error Δφ in the flux linkage number.

Ｒ_ｎ及びＬ_ｎの調整に関しては、数式７を同期モータの電気パラメータを用いて展開すると数式８のようになり、数式８におけるΔｉ_ｄを零とすると、γ_Ｌが１となるようにすればφ_ｄｉｆｆが零となる。

Originally, Δφ _d and Δφ _q need to coincide with each other, and therefore R _n and L _n may be adjusted so that the deviation Δφ _diff between the two expressed in Equation 7 becomes zero.

For the adjustment of R _n and L _n, when developed using electrical parameters of the synchronous motor Equation 7 is as Equation 8, when the zero .DELTA.i _d in Equation 8, if so gamma _L becomes 1 φ _diff becomes zero.

Therefore, as the operation relates to the identification of electrical parameters in the identification unit 10, while controlling the i _d to zero, varying the nominal value L _n of the self-inductance in the current simulator 9, [Delta] [phi _diff equation 7 becomes zero to identify the self-inductance by looking for the value of L _n. Then, the value obtained by identifying the self-inductance L _n of the current simulator controls the i _d to an arbitrary value by varying the nominal value R _n of the armature resistance, the value of R _n which [Delta] [phi _diff equation 7 becomes zero To identify the armature resistance. Finally, the armature resistance R _n and the self-inductance L _n of the current simulator are set to the identified values, and Δφ _d and Δφ _q which are errors of the flux linkage number are obtained by Equation 6, and the flux linkage number φ _fa is identified. To do.

The overall operation relating to the identification of the electrical parameters of the synchronous motor described above will be described using the flowchart of FIG.
First, in order to keep the q-axis current _iq constant, the rotational speed of the synchronous motor 1 is controlled to a constant value (step S1). Next, in step S2, while controlling to zero the d-axis current _{i d} (S2a), so that the deviation [Delta] [phi _diff as shown in Equation 6-8 is zero, adjust the nominal value _{L n} of self-inductance (S2b to S2e). In step S3, the adjusted value as the self-inductance nominal value of the current simulator, the d-axis current i _d while controlling to any value (S3a), so that the deviation [Delta] [phi _diff becomes zero, the armature resistance adjusting the nominal value _{R n (S3b~S3e).} In step S4, after identifying the self-inductance and the armature resistance as described above, Δφ is identified by Equation 6 to adjust the flux linkage number φ _fn .

Next, offset identification of the current detection means 3 in the identification means 10 will be described.
The electrical parameter of the synchronous motor 1 identified above is used as the nominal value of the current simulator 9, and the output of the current simulator as shown in Equation 9, that is, the d-axis estimated current i _d ^ ′, the q-axis estimated current i _q ′ and d Since the deviations Δi _d ^ and Δi _q ^ from the axis detection current i _d and the q axis detection current i _q are offset components of the dq axis, these two axis currents are converted into a three-phase alternating current by Equation 10. Then, offset values Δi _u ^ and Δi _v ^ are obtained. These offset values, as shown in the current detecting means 3 in FIG. 1, will be used to correct the phase currents i _u, i _v.

  The controller for a permanent magnet synchronous motor according to the present invention only provides a period for controlling the d-axis current and the q-axis current to a predetermined value during normal operation without performing a special operation for identification. All the electrical parameters of the synchronous motor can be identified and the offset of the current detection means can also be adjusted. Therefore, the present invention can be used when driving an industrial permanent magnet synchronous motor such as a servo system.

1: Permanent magnet synchronous motor 2: Power converter (PWM inverter)
3: Current detection means 4: Biaxial current conversion means 5: Speed detection means (encoder)
6: Speed control means 7: d-axis current control means 8: q-axis current control means 9: current simulator 10: identification means 11, 12d, 12q, 13u, 13v: addition / subtraction means

Claims (1)

A current control means for calculating a voltage command corresponding to a deviation between a current command of the permanent magnet synchronous motor and a detected current; a power converter for supplying an AC voltage generated according to the voltage command to the motor; and In a control device for a permanent magnet synchronous motor, comprising: current detection means for converting a phase current into a d-axis current and a q-axis current on a dq rotation coordinate;
A current simulator for calculating a d-axis and q-axis estimated current from the state equation of the motor by inputting the rotation speed of the motor and the d-axis and q-axis voltages on the dq rotation coordinates;
With the motor controlled at a constant speed such that the d-axis detection current of the motor becomes zero, the motor, the current simulator, The function of identifying the self-inductance of the motor by adjusting the self-inductance nominal value of the current simulator so that the deviation of the number of flux linkages of the motor becomes zero, and the d-axis detection current of the motor controlled to a predetermined value Using the d-axis and q-axis estimated currents and the d-axis and q-axis detection currents, the armature resistance nominal value of the current simulator is set so that the deviation of the number of flux linkages between the motor and the current simulator becomes zero. A function of adjusting and identifying the armature resistance of the motor, a function of identifying the number of flux linkages of the motor using the d-axis and q-axis estimated currents and the d-axis and q-axis detection currents, and the d From the deviation between the deviation and the q-axis estimated current and the q-axis detection current and the estimated current and the d-axis detection current, and the identification means having a function of identifying an offset value of said current detecting means,
A control apparatus for a permanent magnet synchronous motor, comprising:

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