CN102539070A - Method and system for identifying rotational inertia of alternating current servo system - Google Patents

Abstract

The invention is applicable to the field of motors, and provides a method and a system for identifying the rotational inertia of an alternating current servo system. The method comprises the following steps of: acquiring time, a speed change value, and an average torque of a first speed change stage at the first speed change stage of the alternating current servo system to obtain a first speed change stage motion equation; acquiring time, a speed change value and an average torque of a second speed change stage at the second speed change stage of the alternating current servo system to obtain a second speed change stage motion equation; and calculating rotational inertia according to the difference between the first speed change stage motion equation and the second speed change stage motion equation, wherein the average speed of the first speed change stage is the same as that of the second speed change stage. The technical scheme has the advantages of high identification accuracy of the rotational inertia.

Description

The method for identification of rotational inertia of AC servo and system

Technical field

The invention belongs to machine field, relate in particular to a kind of method for identification of rotational inertia and system of AC servo.

Background technology

The high-performance AC servo system is a high-end technology product, has very critical role at aspects such as aerospace, military affairs, robot and precise numerical control machines.As the AC servo of topworks, compare with other electromechanical assembly, have high precision, good stability, response fast, speed-regulating range width and the big advantage of low speed torque.Approximate dynamic structure figure is as shown in Figure 1 for existing AC servo drive system; In different application scenes; The AC servo performance receives the influence of load disturbance and moment of inertia bigger, and especially moment of inertia is bigger to the servo-drive system performance impact, again because moment of inertia is to be difficult to the directly physical quantity of measurement; So the identification precision of moment of inertia is even more important; The method for identification of rotational inertia of the AC servo that prior art provides specifically comprises: servo-drive system is carried out acceleration and deceleration motion, obtain system's output torque and motor mean speed in this section period, obtain the servo-drive system average torque by system's output torque; In T.T., obtain the value of inertia according to motor mean speed, servo-drive system average torque and system's acceleration and deceleration operation.

According to the technical scheme that prior art provided, find to exist in the prior art following technical matters:

The discrimination method that prior art provides has only been considered the T.T. of average torque, mean speed and acceleration and deceleration operation; Computing formula according to moment of inertia can be known; The coefficient of viscosity that when moment of inertia calculates, also needs taking into account system; Because the technical scheme that prior art provides is not considered the viscous system, so the moment of inertia precision that this method obtains is low.

Summary of the invention

The purpose of the embodiment of the invention is to provide a kind of discrimination method of moment of inertia of AC servo, is intended to solve the low problem of moment of inertia precision that prior art causes owing to the coefficient of viscosity of taking into account system not.

The embodiment of the invention is achieved in that the present invention provides a kind of discrimination method of moment of inertia of AC servo, and said method comprises:

In first gear shift stage of AC servo, obtain time, velocity variations value and the average torque of first gear shift stage, obtain the first gear shift stage equation of motion;

In second gear shift stage of AC servo, obtain time, velocity variations value and the average torque of second gear shift stage, obtain the second gear shift stage equation of motion;

Difference according to the first gear shift stage equation of motion and the second gear shift stage equation of motion calculates moment of inertia; Said first gear shift stage is identical with the average velocity of said second gear shift stage.

The present invention also provides a kind of AC servo, and said system comprises:

Acquiring unit is used for first gear shift stage in AC servo, obtains time, velocity variations value and the average torque of first gear shift stage, obtains the first gear shift stage equation of motion;

Said acquiring unit also is used for second gear shift stage in AC servo, obtains time, velocity variations value and the average torque of second gear shift stage, obtains the second gear shift stage equation of motion;

The moment of inertia recognition unit is used for calculating moment of inertia according to the difference of the first gear shift stage equation of motion and the second gear shift stage equation of motion; Said first gear shift stage is identical with the average velocity of said second gear shift stage.

The embodiment of the invention compared with prior art; Beneficial effect is: first gear shift stage of technical scheme of the present invention is identical with the average velocity of second gear shift stage; So when carrying out moment of inertia calculating according to the difference of the first gear shift stage equation of motion and the second gear shift stage equation of motion; Can effectively eliminate the influence of the coefficient of viscosity, so that it has an identification of rotational inertia is accurate, advantage of high precision.

Description of drawings

Fig. 1 is the approximate dynamic structure figure of AC servo that prior art provides;

Fig. 2 is the process flow diagram of discrimination method of the moment of inertia of a kind of AC servo provided by the invention;

Fig. 3 is AC servo inertia identification process electric current provided by the invention and speed waveform synoptic diagram;

Fig. 4 is the identification and the parameter tuning control block diagram of moment of inertia provided by the invention;

Fig. 5 is the structural drawing of AC servo provided by the invention.

Embodiment

In order to make the object of the invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with accompanying drawing and embodiment.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.

The present invention provides a kind of discrimination method of moment of inertia of AC servo, and this method is as shown in Figure 2, comprises the steps:

S21, in first gear shift stage of AC servo, obtain time, velocity variations value and the average torque of first gear shift stage, obtain the first gear shift stage equation of motion;

S22, in second gear shift stage of AC servo, obtain time, velocity variations value and the average torque of second gear shift stage, obtain the second gear shift stage equation of motion;

S23, calculate moment of inertia according to the difference of the phase one equation of motion and the subordinate phase equation of motion.

Need to prove that above-mentioned first gear shift stage is identical with the average velocity of second gear shift stage.

Need to prove; The average velocity of first gear shift stage and second gear shift stage is identical specifically can be comprised: first gear shift stage and second gear shift stage are uniform variable motion (the even acceleration or even the deceleration); And the starting velocity of first gear shift stage is identical with the cutoff velocity of second gear shift stage, and the cutoff velocity of first gear shift stage is identical with the starting velocity of second gear shift stage.

The above-mentioned method that obtains gear shift stage (is example with the phase one) equation of motion specifically can for, time, velocity variations value and the average torque input motion equation of phase one obtained the phase one equation of motion.

Optional, above-mentioned gear shift stage (first or second) can for: boost phase or decelerating phase specifically can be even boost phase or even decelerating phase.

Need to prove; The acquisition methods of above-mentioned velocity variations value can be (is example with first gear shift stage): measure the starting velocity value of start time point correspondence in first gear shift stage and the cutoff velocity value of first gear shift stage point closing time, velocity variations value=cutoff velocity value-starting velocity value.

Need to prove, the above-mentioned method of obtaining average torque can for: obtain the torque current of gear shift stage (first or second), calculate torque accumulation, average torque=torque accumulation/gear shift stage time according to this torque current; In addition, need to prove torque accumulation=torque current * servo-drive system motor torque coefficient (known constant).Certainly the method for obtaining average torque can also be other method of the prior art.

Need to prove that above-mentioned speed can be angular velocity.

Need to prove that said method can repeatedly repeat above-mentioned S21-S23 and obtain a plurality of moment of inertia, the mean value of getting a plurality of moment of inertia then is to improve the accuracy rate of moment of inertia.

AC servo inertia identification process electric current and speed waveform synoptic diagram are as shown in Figure 3.

Through principle of work of the present invention the technique effect that the present invention reaches is described below.

According to the equation of motion Can know that moment of inertia J is by velocity variations value Δ ω, time Δ t, coefficient of viscosity B, average velocity

Load torque T _LWith average torque T _eDecision; T wherein _e, Δ ω, Δ t can measure or calculate (concrete grammar is referring to foregoing description), this moment, we only needed to eliminate B and T _LGet final product; In the identification of moment of inertia, load is normally constant, so T _LAlso constant, so can eliminate B and T through the difference of the phase one equation of motion and the subordinate phase equation of motion _L, reason is that in the identification of moment of inertia, load is normally constant, so the T of phase one _LThe T of subordinate phase _LIdentical, so above-mentioned difference can effectively be eliminated the influence of load torque to moment of inertia, there is above-mentioned first gear shift stage identical again, then with the average velocity of second gear shift stage

With

Also identical, so this difference also can well be eliminated the influence of coefficient of viscosity B.So said method in identification of rotational inertia, can effectively be eliminated the influence of the coefficient of viscosity and load torque, it is more accurate to have a moment of inertia, advantage of high precision.

The computing method of moment of inertia are described through a real example below, and the identification of this moment of inertia and parameter tuning control block diagram are as shown in Figure 4.

Explanation for ease after here AC servo being started, is 4 stages with the stage definitions of AC servo, respectively corresponding STEP1, STEP2, STEP3, STEP4;

Need to prove that for the ease of the control of average velocity, define STEP1, STEP2, STEP3, STEP4 here and be even the acceleration or even the deceleration, the starting velocity of definition STEP1 is ω _n/ 4, cutoff velocity is ω _n/ 2; The starting velocity of definition STEP2 is ω _n/ 2, cutoff velocity is ω _n/ 4; The starting velocity of definition STEP3 is-ω _n/ 4, cutoff velocity is-ω _n/ 2; The starting velocity of definition STEP4 is-ω _n/ 2, cutoff velocity is-ω _n/ 4;

STEP1.0: set Iq_ref=Iq_set, i.e. T _e_ ref=K _t* Iq_set gets into STEP2.1; Wherein Iq_ref representes the torque current component instruction, and Iq_fbk representes the torque current component feedback; ω _nBe rated angular velocity;

STEP1.1: judge whether speed arrives ω _n/ 4, no show then continues speed governing and reaches ω until speed _n/ 4, IqSum=0, pick up counting (t11), and get into STEP1.2;

STEP1.2: torque current IqSum '=IqSum+Iq_fbk, i.e. torque accumulation: T _eSum=K _t* IqSum '; Judge whether speed arrives ω _n/ 2, no show then continues speed governing and reaches ω until speed _n/ 2, finish timing (t12), obtain at whole the accelerator used time T 1 (t12-t11) and the average torque T that applies _E1=T _eSum/T1;

Need to prove that the torque current that above-mentioned IqSum ' expression is current, IqSum are represented the torque current of the previous moment of IqSum '; Wherein the concrete computing method of IqSum ' can for, suppose from ω _n/ 4 to ω _n/ 2 need carry out speed governing, then IqSum 1000 times ₁=IqSum ₀+ Iq_fbk, IqSum ₂=IqSum ₁+ Iq_fbk......IqSum ₁₀₀₀=IqSum ₉₉₉+ Iq_fbk; IqSum ₁₀₀₀Be IqSum '.

STEP2.0: set Iq_ref=-Iq_set, i.e. T _e_ ref=-K _t* Iq_set gets into STEP2.1;

STEP2.1: judge whether speed arrives ω _n/ 2, no show then scheduling next time continues to carry out STEP3.1, and speed arrives ω _n/ 2, IqSum=0 then picks up counting (t21), and gets into STEP2.2;

STEP2.2: torque current IqSum ' ₂=IqSum ₂+ Iq_fbk, i.e. torque accumulation T _eSum ₂=K _t* IqSum ' ₂Judge whether speed arrives ω _n/ 4, no show then continues speed governing and reaches ω until speed _nFinished timing (t22) at/4 o'clock, obtain at whole the moderating process used time T 2 (t22-t21) and the average torque T that applies _E2=T _eSum ₂/ T2; And entering STEP3.1;

STEP3.1: judge whether speed arrives-ω _n/ 4 no shows then continue speed governing until reaching-ω _n/ 4, speed reaches and IqSum ₃=0, pick up counting (t31), and get into STEP3.2;

STEP3.2 torque current IqSum ' ₃=IqSum ₃+ Iq_fbk, i.e. torque accumulation: T _eSum ₃=K _t* IqSum ' ₃Judge whether speed arrives-ω _n/ 2, no show then continues speed governing and reaches until speed, finishes timing (t32), obtains at whole the accelerator used time T 3 (t32-t31) and the average torque T that applies _E3=T _eSum ₃/ T3;

STEP4.0: set Iq_ref=-Iq_set, get into STEP4.1;

STEP4.1: judge whether speed arrives-ω _n/ 2, no show then scheduling next time continues speed governing until speed arrival-ω _n/ 2, pick up counting (t41), and get into STEP4.2;

STEP4.2: torque current IqSum ' ₄=IqSum ₄+ Iq_fbk, i.e. torque accumulation: T _eSum ₄=K _t* IqSum ' ₄, judge whether speed arrives-ω _n/ 4, no show then continues speed governing and reaches-ω until speed _n/ 4, finish timing (t42), obtain at the fast process of whole the deceleration used time T 4 (t42-t41) and the average torque T that applies _E4=T _eSum ₄/ T4;

According to the equation of motion:

and STEP1～STEP4 can obtain (1)～(4)

Equation:

$\left\{\begin{array}{cc}J\frac{\mathrm{\&Delta;}{\mathrm{\&omega;}}_1}{{\mathrm{\&Delta;<figure-callout\; id="1"\; label="t"\; filenames="HDA0000041769790000011.png"\; state="\{\{state\}\}">t</figure-callout>}}_1}+B\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_1}+T_L=T_{e1}& \left(1\right)\\ J\frac{{\mathrm{\&Delta;\&omega;}}_2}{{\mathrm{\&Delta;<figure-callout\; id="2"\; label="t"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">t</figure-callout>}}_2}+B\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_2}+T_L=T_{e2}& \left(2\right)\\ J\frac{{\mathrm{\&Delta;\&omega;}}_3}{{\mathrm{\&Delta;<figure-callout\; id="3"\; label="t"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">t</figure-callout>}}_3}+B\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_3}+T_L=T_{e3}& \left(3\right)\\ J\frac{{\mathrm{\&Delta;\&omega;}}_4}{{\mathrm{\&Delta;<figure-callout\; id="4"\; label="t"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">t</figure-callout>}}_4}+B\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_4}+T_L=T_{e4}& \left(4\right)\end{array}\right.$

Wherein:

T _LBe load torque (unknown quantity),

Δω ₁＝ω _n/2-ω _n/4＝ω _n/4；Δt ₁＝t11-t12＝T1

Δω ₂＝ω _n/4-ω _n/2＝-ω _n/4；Δt ₂＝t21-t22＝T2

Δω ₃＝-ω _n/2+ω _n/4＝-ω _n/4；Δt ₃＝t31-t32＝T3

Δω ₄＝-ω _n/4+ω _n/2＝ω _n/4；Δt ₄＝t41-t42＝T4

Because be that whole identification process quickens or even the deceleration for even, T1, T2, T3, T4 average velocity are:

$\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_1}={\mathrm{\&Delta;\&omega;}}_1/2+{\mathrm{\&omega;}}_n/4=3{\mathrm{\&omega;}}_n/8$

$\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_2}={\mathrm{\&Delta;\&omega;}}_2/2+{\mathrm{\&omega;}}_n/2=3{\mathrm{\&omega;}}_n/8$

$\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_3}={\mathrm{\&Delta;\&omega;}}_3/2-{\mathrm{\&omega;}}_n/4=-3{\mathrm{\&omega;}}_n/8$

$\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_4}={\mathrm{\&Delta;\&omega;}}_4/2-{\mathrm{\&omega;}}_n/2=-3{\mathrm{\&omega;}}_n/8$

Through (1) formula-(2) formula, (3) formula-(4) formula, peel load torque T _L:

$\left\{\begin{array}{cc}J(\frac{{\mathrm{\&Delta;\&omega;}}_1}{{\mathrm{\&Delta;t}}_1}-\frac{{\mathrm{\&Delta;\&omega;}}_2}{{\mathrm{\&Delta;t}}_2})+B(\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_1}-\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_2})=T_{e1}-T_{e2}& \left(5\right)\\ J(\frac{{\mathrm{\&Delta;\&omega;}}_3}{{\mathrm{\&Delta;t}}_3}-\frac{{\mathrm{\&Delta;\&omega;}}_4}{{\mathrm{\&Delta;t}}_4})+B(\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_3}-\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_4})=T_{e3}-T_{e4}& \left(6\right)\end{array}\right.$

(5)-(6) formula gets:

$J(\frac{{\mathrm{\&Delta;\&omega;}}_1}{{\mathrm{\&Delta;t}}_1}-\frac{{\mathrm{\&Delta;\&omega;}}_2}{{\mathrm{\&Delta;t}}_2}-\frac{{\mathrm{\&Delta;\&omega;}}_3}{{\mathrm{\&Delta;<figure-callout\; id="3"\; label="t"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">t</figure-callout>}}_3}+\frac{{\mathrm{\&Delta;\&omega;}}_4}{{\mathrm{\&Delta;t}}_4})+B(\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_1}-\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_2}-\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_3}+\stackrel{\&OverBar;}{{\mathrm{\&omega;}}_4})=T_{e1}-T_{e2}-{\mathrm{<figure-callout\; id="3"\; label="T\; e"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">T</figure-callout>}}_e+T_{e4}---\left(7\right)$

By above-mentioned

thereby the influence that can eliminate the coefficient of viscosity fully and produced:

$J=(T_{e1}-T_{e2}-{\mathrm{<figure-callout\; id="3"\; label="T\; e"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">T</figure-callout>}}_e+T_{e4})/(\frac{{\mathrm{\&Delta;\&omega;}}_1}{{\mathrm{\&Delta;t}}_1}-\frac{{\mathrm{\&Delta;\&omega;}}_2}{{\mathrm{\&Delta;t}}_2}-\frac{{\mathrm{\&Delta;\&omega;}}_3}{{\mathrm{\&Delta;<figure-callout\; id="3"\; label="t"\; filenames="HDA0000041769790000021.png"\; state="\{\{state\}\}">t</figure-callout>}}_3}+\frac{{\mathrm{\&Delta;\&omega;}}_4}{{\mathrm{\&Delta;t}}_4})---\left(8\right);$

So the influence that this method when the identification moment of inertia, can be eliminated the coefficient of viscosity fully and produced is so it has accuracy height, advantage of high precision.

The present invention also provides a kind of AC servo, and this system is as shown in Figure 5, specifically comprises:

Acquiring unit 51 is used for first gear shift stage in AC servo, obtains time, velocity variations value and the average torque of first gear shift stage, obtains the first gear shift stage equation of motion;

Acquiring unit 51 also is used for second gear shift stage in AC servo, obtains time, velocity variations value and the average torque of second gear shift stage, obtains the second gear shift stage equation of motion;

Moment of inertia recognition unit 52 is used for calculating moment of inertia according to the difference of the first gear shift stage equation of motion and the second gear shift stage equation of motion; Said first gear shift stage is identical with the average velocity of said second gear shift stage.

Optional, said system also comprises:

Cycling element 53 is used to trigger acquiring unit 51 and carries out circular treatment with moment of inertia recognition unit 52 and obtain a plurality of moment of inertia, gets the mean value of a plurality of moment of inertia.

System provided by the invention is adjusted to the identical influence of eliminating the coefficient of viscosity to moment of inertia through the average velocity with first gear shift stage and second gear shift stage, so that it has an identification of rotational inertia is more accurate, and advantage of high precision.

It should be noted that said system, each included unit is just divided according to function logic, but is not limited to above-mentioned division, as long as can realize function corresponding; In addition, the concrete title of each functional unit also just for the ease of mutual differentiation, is not limited to protection scope of the present invention.

In addition; One of ordinary skill in the art will appreciate that all or part of step that realizes in the foregoing description method is to instruct relevant hardware to accomplish through program; Corresponding program can be stored in a kind of computer-readable recording medium; The above-mentioned storage medium of mentioning can be a ROM (read-only memory), disk or CD etc.

In sum, it is more accurate that technical scheme provided by the invention has an identification of rotational inertia, advantage of high precision.

The above is merely preferred embodiment of the present invention, not in order to restriction the present invention, all any modifications of within spirit of the present invention and principle, being done, is equal to and replaces and improvement etc., all should be included within protection scope of the present invention.

Claims (8)

1. the discrimination method of the moment of inertia of an AC servo is characterized in that, said method comprises:

In first gear shift stage of AC servo, obtain time, velocity variations value and the average torque of first gear shift stage, obtain the first gear shift stage equation of motion;

In second gear shift stage of AC servo, obtain time, velocity variations value and the average torque of second gear shift stage, obtain the second gear shift stage equation of motion;

Difference according to the first gear shift stage equation of motion and the second gear shift stage equation of motion calculates moment of inertia; Said first gear shift stage is identical with the average velocity of said second gear shift stage.

2. method according to claim 1 is characterized in that, said gear shift stage comprises: the even acceleration or the even decelerating phase.

3. method according to claim 1 is characterized in that, the average velocity of said first gear shift stage and said second gear shift stage is identical specifically to be comprised:

Said first gear shift stage is even gear shift stage, and said second gear shift stage is even gear shift stage; The starting velocity of said phase one is identical with the cutoff velocity of said subordinate phase, and the starting velocity of said subordinate phase is identical with the cutoff velocity of said phase one.

4. method according to claim 1 is characterized in that, the method for obtaining average torque is specially:

Obtain the torque current of gear shift stage, calculate torque accumulation, average torque=torque accumulation/gear shift stage time according to this torque current.

5. an AC servo is characterized in that, said system comprises:

Acquiring unit is used for first gear shift stage in AC servo, obtains time, velocity variations value and the average torque of first gear shift stage, obtains the first gear shift stage equation of motion;

Said acquiring unit also is used for second gear shift stage in AC servo, obtains time, velocity variations value and the average torque of second gear shift stage, obtains the second gear shift stage equation of motion;

The moment of inertia recognition unit is used for calculating moment of inertia according to the difference of the first gear shift stage equation of motion and the second gear shift stage equation of motion; Said first gear shift stage is identical with the average velocity of said second gear shift stage.

6. system according to claim 5 is characterized in that, said gear shift stage comprises: the even acceleration or the even decelerating phase.

7. system according to claim 5 is characterized in that, the average velocity of said first gear shift stage and said second gear shift stage is identical specifically to be comprised:

Said first gear shift stage is even gear shift stage, and said second gear shift stage is even gear shift stage; The starting velocity of said phase one is identical with the cutoff velocity of said subordinate phase, and the starting velocity of said subordinate phase is identical with the cutoff velocity of said phase one.

8. system according to claim 5 is characterized in that, said system also comprises:

Cycling element is used to trigger said acquiring unit and moment of inertia recognition unit and carries out circular treatment and obtain a plurality of moment of inertia, gets the mean value of a plurality of moment of inertia.

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