CN105406786A - Rotational inertia identification method for permanent magnet synchronous motor - Google Patents

Abstract

The invention relates to a rotational inertia identification method for a permanent magnet synchronous motor. The method comprises the following steps: building a reference model of unknown parameters, comparing the reference model with an actual model, and then adjusting the parameters of the reference model according to an algorithm; when an output deviation between the two models does not change basically, approximately replacing the actual model with the reference model, and feeding the identified result back to the reference model of the unknown parameters in the overall identification process; and improving the overall identification accuracy and rapidity by improving corresponding variable factors. According to the rotational inertia identification method, real-time detection can be carried out, so that a basis is laid for subsequent PI controller parameter self-tuning.

Description

A kind of permagnetic synchronous motor method for identification of rotational inertia

Technical field

The present invention relates to permagnetic synchronous motor technical field, particularly relate to a kind of permagnetic synchronous motor method for identification of rotational inertia.

Background technology

Along with permagnetic synchronous motor material property improve constantly and perfect, permagnetic synchronous motor is simple towards structure, high efficiency, high power density and miniaturization, and there is the advantages such as volume is little, non-carbonate, quick response, be applied widely in servo occasion.Due at industrial automation, particularly in the field that the control precisions such as robot, Aero-Space, Digit Control Machine Tool, special equipment processing are high, the performance requirement proposed it is also more and more higher.And in industrial sewing machines industry, to which proposing more harsh requirement.

Current permagnetic synchronous motor is substantially all adopt three close-loop control structure, and inner ring is current regulator, and middle ring is speeds control ring, and outer shroud is position ring.Controller adopts pi regulator, and the effect of electric current loop is the rapidity of raising system, suppresses the interference of current internal; The effect of speed ring is then the ability of raising system anti-disturbance, and suppress the fluctuation of speed, the effect of position ring is then make motor movement arrive given position.

Permagnetic synchronous motor be in essence one non-linear, many time become, the system of close coupling.In actual motion, the change of load, the change of running environment all can cause the parameter such as moment of inertia, friction factor to change.And the change of moment of inertia, then can reduce the stability of whole control system.This not only can cause system dynamic response to slow down, and more likely causes the instability of whole control system.Therefore the moment of inertia of identification permagnetic synchronous motor is necessary.

The identification of moment of inertia is a heat subject in motor servo control field, and existing method for identification of rotational inertia mainly contains acceleration and deceleration method, least square method, state observer method, Kalman filtering discrimination method etc., but all there is different shortcomings in these algorithms.

Summary of the invention

Technical problem to be solved by this invention is to provide a kind of permagnetic synchronous motor method for identification of rotational inertia, can detect in real time, for follow-up PI controller parameter Self-tuning System lays the foundation.

The technical solution adopted for the present invention to solve the technical problems is: provide a kind of permagnetic synchronous motor method for identification of rotational inertia, set up the reference model of unknown parameter, contrast with realistic model, then the parameter of reference model is regulated according to algorithm, when the output bias of two models is substantially constant, approximate reference model replaces realistic model, and in whole identification process, by identification result feedback out in the reference model of band unknown parameter, by improving corresponding variable factor, improve accuracy and the rapidity of whole identification.

Described reference model is ω (k)=2 ω (k-1)-ω (k-2)+z (k) × b (k), wherein, t _sfor the sampling period, J is the moment of inertia summation of rotor and load, $z\left(k\right)=1.5{\mathrm{P\Ψ}}_f\[\frac{6}{9}{i}_q\left(k\right)-\frac{4}{9}{i}_q(k-1)-\frac{1}{9}{i}_q(k-2)-\frac{1}{9}{i}_q(k-3)\],$ Wherein, i _qfor stator q shaft current, Ψ _ffor permanent magnet flux linkage, P is number of pole-pairs; Realistic model is the output bias of two models is $\mathrm{\ϵ}\left(k\right)=\mathrm{\ω}\left(k\right)-\widehat{\mathrm{\ω}}\left(k\right),$ The iterative formula of identification algorithm is $\hat{b}\left(k\right)=\hat{b}(k-1)+\mathrm{\β}\frac{z\left(k\right)\×\mathrm{\ϵ}\left(k\right)}{1+{\mathrm{\βz}}^2(k-1)},$ Wherein β be greater than 0 adaptive gain, in order to do a compromise selection to the value of β, therefore an error E value is set, order s function is used to write subprogram, when E value changes in different range, select different β value to feed back in recognition module and change gain factor, finally when b (k) value is substantially constant, just pick out the moment of inertia summation J of rotor and load.

Described permagnetic synchronous motor adopts i _d ^*the control strategy of=0, the equation of motion of permagnetic synchronous motor is: electromagnetic torque equation is: T _e=1.5P [ψ _fi _q+ (L _d-L _q) i _di _q], wherein: i _d, i _qbe respectively stator d, q shaft current; L _d, L _qbe respectively stator d, q axle inductance, ψ _ffor permanent magnet flux linkage; P is number of pole-pairs; T _efor the electromagnetic torque that motor produces; T _lfor total load torque that rotor bears; J is the moment of inertia summation of rotor and load; ω _mfor the output mechanical angle speed of rotor, t is the time.

The concrete control method of described permagnetic synchronous motor comprises the following steps:

(1) detect permagnetic synchronous motor threephase stator electric current, and the current component that coordinate transform obtains under two-phase rest frame is carried out to threephase stator electric current;

(2) carry out static-rotation transformation again according to the current component under motor electrical degree and two-phase rest frame, obtain the current value i under two-phase synchronous rotating frame _dand i _q;

(3) motor rotate speed feedback value and given rotary speed instruction are compared, its difference is as the input of speed pi regulator, and the output of speed pi regulator is then as the input of q shaft current pi regulator;

(4) by current value i _dcompare with given d shaft current value, its difference as the input of d shaft current ring pi regulator, by current value i _qcompare with the input value of q shaft current pi regulator, its difference, as the input of q shaft current ring pi regulator, through the calculating of d, q shaft current pi regulator, obtains the output voltage U of d, q shaft current ring pi regulator respectively _d, U _q;

(5) the output voltage U obtained _d, U _qu is obtained through IPARK conversion with motor electrical degree _α, U _β, by U _α, U _βbe input to space vector pulse width modulation module, space vector pulse width modulation module calculates the duty ratio of three-phase, and the three-phase PWM waveform of output response is to inverter, exports three-phase voltage drive permagnetic synchronous motor to run by inverter.

Beneficial effect

Owing to have employed above-mentioned technical scheme, the present invention compared with prior art, there is following advantage and good effect: the present invention adopts the algorithm based on MRAS and feedback principle, there is calculating easy, convergence error is little, the advantages such as fast convergence rate, and can be that later PI controller parameter Self-tuning System is prepared according to identification moment of inertia out.In industrial practical application, this algorithm can be transplanted to the change of the moment of inertia also monitoring motor in control software design in real time, thus take counter-measure according to actual condition, make whole control system antijamming capability stronger.

Accompanying drawing explanation

Fig. 1 is system block diagram of the present invention;

Fig. 2 is the simulating schematic diagram that the present invention builds;

Fig. 3 is recognition module analogous diagram of the present invention;

Fig. 4 is feedback speed waveform figure;

Fig. 5 is identification of rotational inertia value oscillogram;

Fig. 6 is identifier oscillogram when moment of inertia being increased 5 times.

Embodiment

Below in conjunction with specific embodiment, set forth the present invention further.Should be understood that these embodiments are only not used in for illustration of the present invention to limit the scope of the invention.In addition should be understood that those skilled in the art can make various changes or modifications the present invention, and these equivalent form of values fall within the application's appended claims limited range equally after the content of having read the present invention's instruction.

Permagnetic synchronous motor method for identification of rotational inertia general principle figure based on MRAS and feedback principle algorithm of the present invention as shown in Figure 1, set up the reference model of unknown parameter, contrast with realistic model, then the parameter of adjustable model is regulated according to algorithm, when the output bias of two models is substantially constant, can be similar to and replace realistic model with reference model, namely unknown parameter has been picked out, and in whole identification process, by identification result feedback out in the reference model of band unknown parameter, and improve corresponding variable factor by program, improve accuracy and the rapidity of whole identification.

The present invention is that research object sets up its vector control system with permagnetic synchronous motor, as shown in Figure 2, coder module, permagnetic synchronous motor, d and q shaft current ring pi regulator, speed ring pi regulator, coordinate transformation module, SVPWM module, IGBT module and identification of rotational inertia module etc. are comprised.

The vector control Principle of Process that the present invention adopts is as described below: the signal that encoder will collect, and obtains feedback rotating speed n through speed and position conversion module, and with given rotary speed instruction n ^*compare, its difference is as the input of speed pi regulator, and the output of speed pi regulator inputs to definite value i then as q shaft current pi regulator ^* _q; The permagnetic synchronous motor threephase stator current i that current sensor will detect _a, i _b, i _cinput in coordinate transform CLARK module and carry out 3/2 conversion, obtain the current component i under rest frame _α, i _β; In PARK conversion module, according to the motor electrical degree θ calculated _e=P × θ _m, (wherein P is the number of pole-pairs of motor, θ _mthat motor exports mechanical angle) and CLARK convert current component i under the two-phase rest frame obtained _α, i _β, carry out static-rotation (2s/2r) conversion, obtain the current value i under two-phase synchronous rotating frame _d, i _q; The current value i will obtained again _dwith given d shaft current set-point i _d ^*compare, its difference as the input of d shaft current ring pi regulator, current value i _qthe q shaft current set-point i obtained is exported with speed ring ^* _qcompare, its difference, as the input of q shaft current ring pi regulator, through the calculating of d, q shaft current pi regulator, can obtain the output voltage U of d, q shaft current ring pi regulator respectively _d, U _q; Again by the output voltage U obtained _d, U _qwith the electric angle angle value θ of motor _eu is obtained through IPARK conversion _α, U _β, by U _α, U _βbe input to SVPWM module, SVPWM module calculates the duty ratio of three-phase, and the three-phase PWM waveform of output response is to inverter, exports three-phase voltage drive permagnetic synchronous motor to run by inverter.

The equation of motion of surface-mount type permagnetic synchronous motor is such as formula shown in (1):

$J\×\frac{{\mathrm{d\ω}}_m}{dt}=T_e-T_l---\left(1\right)$

Electromagnetic torque equation is such as formula shown in (2):

T _e＝1.5P[ψ _fi _q+(L _d-L _q)i _di _q](2)

Wherein: i _d, i _qbe respectively stator d, q shaft current; L _d, L _qbe respectively stator d, q axle inductance, the permagnetic synchronous motor for surface-mount type has, L _d=L _q, ψ _ffor permanent magnet flux linkage; P is number of pole-pairs; T _efor the electromagnetic torque that motor produces; T _lfor total load torque that rotor bears, comprise friction torque etc.; J is the moment of inertia summation of rotor and load; ω _mfor the output mechanical angle speed of rotor.

Discretization is carried out to formula (1) and obtains the discrete form of motor movement equation such as formula shown in (3):

$J\frac{\mathrm{\ω}\left(k\right)-\mathrm{\ω}(k-1)}{T_s}=T_e\left(k\right)-T_l\left(k\right)---\left(3\right)$

Wherein T _ek () is a sampling period T _smedium velocity is changed to the electromagnetic torque mean value of the motor of ω (k) by ω (k-1).

T _ek () can by interpolation calculation, computational methods are such as formula shown in (4):

$T_e\left(k\right)=1.5{\mathrm{P\ψ}}_f\[\frac{1}{9}{i}_q(k-2)+\frac{2}{9}{i}_q(k-1)+\frac{6}{9}{i}_q\left(k\right)\]---\left(4\right)$

Motor is in actual motion, and in a control cycle, the possibility of acute variation is very little, therefore can be similar to and think that load is substantially constant, namely such as formula shown in (5):

T _l(k)＝T _l(k-1)(5)

Formula (3) sampling period of delay is obtained:

$J\frac{\mathrm{\ω}(k-1)-\mathrm{\ω}(k-2)}{T_s}=T_e(k-1)-T_l(k-1)---\left(6\right)$

Formula (3) and formula (6) are subtracted each other, obtain:

$\mathrm{\ω}\left(k\right)=2\mathrm{\ω}(k-1)-\mathrm{\ω}(k-2)+\frac{T_s}{J}\[T_e\left(k\right)-T_e(k-1)\]---\left(7\right)$

Formula (2) is substituted into formula (7) arrange:

$\mathrm{\ω}\left(k\right)=2\mathrm{\ω}(k-1)-\mathrm{\ω}(k-2)+\frac{1.5{\mathrm{P\ψ}}_f{T}_s}{J}\[\frac{6}{9}{i}_q\left(k\right)-\frac{4}{9}{i}_q(k-1)-\frac{1}{9}{i}_q(k-2)-\frac{1}{9}{i}_q(k-3)\]---\left(8\right)$

Order $z\left(k\right)=1.5{\mathrm{P\ψ}}_f\[\frac{6}{9}{i}_q\left(k\right)-\frac{4}{9}{i}_q(k-1)-\frac{1}{9}{i}_q(k-2)-\frac{1}{9}{i}_q(k-3)\],\frac{T_s}{J}=b\left(k\right),$ Then formula (8) abbreviation is:

ω(k)＝2ω(k-1)-ω(k-2)+z(k)×b(k)(9)

With formula (9) for reference model, then estimation model is:

$\widehat{\mathrm{\ω}}\left(k\right)=2\mathrm{\ω}(k-1)-\mathrm{\ω}(k-2)+z\left(k\right)\×\hat{b}\left(k\right)---\left(10\right)$

The deviation of two models is:

$\mathrm{\ϵ}\left(k\right)=\mathrm{\ω}\left(k\right)-\widehat{\mathrm{\ω}}\left(k\right)---\left(11\right)$

The object of identification is exactly to make the deviation of two models more and more less, until substantially no longer change and in allowed limits, so just can go to replace actual value by estimated value, thus obtain a result.

Variable due to identification is the rotor of permagnetic synchronous motor and the moment of inertia summation J of load, therefore will design a kind of alternative manner, J is restrained, and has according to MRAS algorithm iteration formula:

$\hat{b}\left(k\right)=\hat{b}(k-1)+\mathrm{\β}\frac{z\left(k\right)\×\mathrm{\ϵ}\left(k\right)}{1+{\mathrm{\βz}}^2(k-1)}---\left(12\right)$

Consider and will take into account Identification Errors and identification convergence time, need to do a compromise selection to the value of β, therefore an error E value is set, order use S function to write subprogram, by different E values, select different β value to feed back in recognition module, pick out b (k), also just picked out the moment of inertia summation J of rotor and load.

In order to verify the validity of the method, built simulation model as shown in Figure 3, the simulation parameter of the motor chosen is 2 to pole, and stator resistance is 2.875 Ω, and stator d, q axle inductance is 8.5mH, and permanent magnet flux linkage is 0.175Wb, and moment of inertia is 0.0006K _gm ².Speed command is sinusoidal signal, and peak value is 500r/min, and the cycle is 0.01s, and the load torque of motor is set to 1Nm.Taking from the suitable solution cycle is 0.006s, β feeds back to S function by the J value picked out, error E is calculated in S function, by different E values, select different β value, to improve the precision of identification, simulation result figure as shown in Figure 4, Figure 5, as can be seen from Figure 4, feedback rotating speed can tracing preset speed, and tracking effect is very good.Identification moment of inertia value out can be obtained from Fig. 5 and be about 0.0006K _gm ², relative error is about 5%, and the time that J reaches stationary value is about 0.25s, and identification is effective.

In order to verify identification algorithm further, moment of inertia is increased 5 times, also namely the moment of inertia of motor itself is 0.003K _gm ², again emulate, as shown in Figure 6, as can be seen from Figure 6, identification moment of inertia value is out about 0.003K to the simulation waveform drawn _gm ², relative error is about 6%, and make from different before, the time that J reaches stationary value shortens greatly, is about 0.05s, and therefore identification result is still effective.

Claims (4)

1. a permagnetic synchronous motor method for identification of rotational inertia, it is characterized in that, set up the reference model of unknown parameter, contrast with realistic model, then regulate the parameter of reference model according to algorithm, when the output bias of two models is substantially constant, approximate reference model replaces realistic model, and in whole identification process, by identification result feedback out in the reference model of band unknown parameter, by improving corresponding variable factor, improve accuracy and the rapidity of whole identification.

2. permagnetic synchronous motor method for identification of rotational inertia according to claim 1, it is characterized in that, described reference model is ω (k)=2 ω (k-1)-ω (k-2)+z (k) × b (k), wherein t _sin the sampling period, J is the moment of inertia summation of rotor and load, $z\left(k\right)=1.5{\mathrm{P\Ψ}}_f\[\frac{6}{9}{i}_q\left(k\right)-\frac{4}{9}{i}_q(k-1)-\frac{1}{9}{i}_q(k-2)-\frac{1}{9}{i}_q(k-3)\],$ Wherein, i _qfor stator q shaft current, Ψ _ffor permanent magnet flux linkage, P is number of pole-pairs; Realistic model is $\widehat{\mathrm{\ω}}\left(k\right)=2\mathrm{\ω}(k-1)-\mathrm{\ω}(k-2)+z\left(k\right)\×\hat{b}\left(k\right);$ The output bias of two models is $\mathrm{\ϵ}\left(k\right)=\mathrm{\ω}\left(k\right)-\widehat{\mathrm{\ω}}\left(k\right),$ The iterative formula of identification algorithm is wherein β be greater than 0 adaptive gain, in order to do a compromise selection to the value of β, therefore an error E value is set, order s function is used to write subprogram, when E value changes in different range, select different β value to feed back in recognition module and change gain factor, finally when b (k) value is substantially constant, just pick out the moment of inertia summation J of rotor and load.

3. permagnetic synchronous motor method for identification of rotational inertia according to claim 1, is characterized in that, described permagnetic synchronous motor adopts i _d ^*the control strategy of=0, the equation of motion of permagnetic synchronous motor is: electromagnetic torque equation is: T _e=1.5P [ψ _fi _q+ (L _d-L _q) i _di _q], wherein: i _d, i _qbe respectively stator d, q shaft current; L _d, L _qbe respectively stator d, q axle inductance, ψ _ffor permanent magnet flux linkage; P is number of pole-pairs; T _efor the electromagnetic torque that motor produces; T _lfor total load torque that rotor bears; J is the moment of inertia summation of rotor and load; ω _mfor the output mechanical angle speed of rotor, t is the time.

4. permagnetic synchronous motor method for identification of rotational inertia according to claim 3, is characterized in that, the concrete control method of described permagnetic synchronous motor comprises the following steps:

(1) detect permagnetic synchronous motor threephase stator electric current, and the current component that coordinate transform obtains under two-phase rest frame is carried out to threephase stator electric current;

(2) carry out static-rotation transformation again according to the current component under motor electrical degree and two-phase rest frame, obtain the current value i under two-phase synchronous rotating frame _dand i _q;

(3) motor rotate speed feedback value and given rotary speed instruction are compared, its difference is as the input of speed pi regulator, and the output of speed pi regulator is then as the input of q shaft current pi regulator;

(4) by current value i _dcompare with given d shaft current value, its difference as the input of d shaft current ring pi regulator, by current value i _qcompare with the input value of q shaft current pi regulator, its difference, as the input of q shaft current ring pi regulator, through the calculating of d, q shaft current pi regulator, obtains the output voltage U of d, q shaft current ring pi regulator respectively _d, U _q;

(5) the output voltage U obtained _d, U _qu is obtained through IPARK conversion with motor electrical degree _α, U _β, by U _α, U _βbe input to space vector pulse width modulation module, space vector pulse width modulation module calculates the duty ratio of three-phase, and the three-phase PWM waveform of output response is to inverter, exports three-phase voltage drive permagnetic synchronous motor to run by inverter.