CN102510260A - Induction machine vector control method taking account of iron loss - Google Patents

Abstract

The invention provides an induction machine vector control method taking account of iron loss adopts dual closed-loop control of an outer speed loop and an inner current loop, wherein the outer speed loop adopts the rotational speed PI modulating control of a motor and outputs a torque current instruction value of the inner current loop; the inner current loop adopts torque current and field current PI modulating control; in the inner current loop, the torque current and the field current are respectively compensated; and the compensated torque current and field current components are led into the current PI regulation. The induction machine vector control method takes the influence of iron loss on the field orientation and the field intensity into consideration, and improves the field orientation accuracy and control performance of a traditional induction machine vector control method, particularly the speed operating precision in a weak magnetic region and the stability in current control.

Description

A kind of induction Motor Vector Control method of considering iron loss

Technical field

The invention belongs to AC induction motor and control technology field thereof, be specifically related to a kind of induction Motor Vector Control method of considering iron loss.

Background technology

The ac motor speed control by variable frequency method mainly comprises open loop V/f speed governing and closed-loop drive, and the closed-loop drive vector control method that is otherwise known as specifically comprises rotor field-oriented indirectly, direct rotor field-oriented, direct stator flux orientation etc.Its indirect is rotor field-oriented because the hardware that needs is few, and control performance is high and be widely used.

The indirect rotor field-oriented vector control principle of induction machine is: rotating coordinate system is based upon on the direction of rotor field; And through this coordinate; Stator current is decomposed into torque current and excitation current component, thereby realizes the size control of output torque and rotor field respectively.The rotor field angle obtains through rotor-position and slip angle addition calculation.The slip angle is passed through the slip speed integration is obtained, and slip speed then is to calculate through torque current and field supply.

During operation below the induction machine base speed, it is constant that exciting current keeps, and is generally the 30%-50% of rated current, is in than higher levels of current.When moving more than the motor base speed, exciting current can descend along with the rising of rotating speed, and when higher rotation speed, exciting current will be in lower, even extremely low level.

The loss that eddy current in the coil and the magnetic hysteresis in the magnet produce is called as iron loss, and it increases along with the increase of power frequency, increases along with the increase in magnetic field, and it is embodied in, and the motor feels hot and magnetic field linearity variation.When moving below the induction machine base speed, magnetic field remains unchanged, and along with the rising of power frequency, its iron loss can constantly increase, but because field supply is bigger, iron loss almost can be ignored to the influence in magnetic field.But along with the rising of speed, because field supply constantly reduces, the rotor field level decreases; Under this situation; Iron loss can not be ignored the influence of rotor field again, and the conventional vector control method of extensive use is not at present considered the influence of iron loss to field orientation precision and magnetic field size, therefore; The conventional vector control method is difficult to satisfy the demand of performance application occasion for high speed weak magnetic area and inapplicable.

Summary of the invention

The purpose of this invention is to provide a kind of induction Motor Vector Control method of considering iron loss; Do not consider the influence of iron loss to solve the conventional vector control method; Cause weak magnetic high velocity field orientation inaccurate; The true field size is given inconsistent with system, and then the problem that makes the weak magnetic high velocity control performance decline of system.

A kind of induction Motor Vector Control method of considering iron loss; Two closed-loop controls of employing speed outer shroud and current inner loop, speed outer shroud adopt motor speed PI to regulate control, and it is output as the torque current command value of current inner loop; Current inner loop adopts walk around square electric current and field supply PI adjusting control; It is characterized in that, in current inner loop, respectively torque current and field supply are compensated; And in torque current after will compensating and the adjusting of field supply component introducing current PI, the iron loss compensation term of torque current and field supply is respectively

And T _Feω _ei _Dm, wherein, L _rBe the rotor inductance, L _LrBe the rotor leakage inductance,

L _mBe the motor mutual inductance, R _FeBe motor equivalence iron loss resistance, ω _eBe synchronous angular velocity, i _DmAnd i _QmBe respectively d axle and q axle excitation current component.

Objective for implementation of the present invention is for adopting the Induction Motor Drive system of vector control.Compare with conventional vector control, only need increase the iron loss compensate component respectively to torque current and field supply component can realize, explicit physical meaning, and need not adjust the vector control structure, realize simply.Concrete technique effect of the present invention embodies as follows:

1) in the indirect rotor field-oriented vector control, the angle of rotor field is to obtain through rotor-position and slip angular velocity integration, and the calculating of slip angular velocity then needs torque current and field supply component accurately.Through compensation, and participate in the control of current PI adjuster, thereby effectively improved the accuracy of torque current and field supply, and then guarantee the accuracy of field orientation iron loss;

2) through compensation, make the desired magnetic field of motor true field and system be consistent, help effective control big or small in the weak magnetic process, improve the utilance of electric current, strengthen the torque fan-out capability magnetic field to field supply;

3) when magnetic tachometer a little less than the motor when higher since magnetic field levels a little less than, iron loss influence proportion and increases, and iron loss is compensated significantly improving performance and the stability that system controls.

Description of drawings

Fig. 1 is the vector control block diagram that comprises iron loss;

Fig. 2 is the equivalent electric circuit that induction machine comprises iron loss, and Fig. 2 (a) is a d axle equivalent electric circuit under the rotating coordinate system, and Fig. 2 (b) is a q axle equivalent electric circuit under the rotating coordinate system;

Fig. 3 is an induction machine high velocity Physical Experiment curve, Fig. 3 (a) be speed-up ratio than waveform, abscissa is the time, unit: the 0.05s/ lattice; Ordinate is time rev/min, and Fig. 3 (b) is speed one a stator voltage curve, and abscissa is a speed; Unit: rev/min, ordinate is a voltage, unit: volt/lattice.

Embodiment

In order to solve the existing problem of conventional vector control method, the present invention proposes a kind of induction Motor Vector Control mode of considering iron loss.

1) as shown in Figure 2 according to the induction machine equivalent electric circuit that comprises iron loss, derivation obtains induction Motor Vector Control and has following expression formula:

$v_{\mathrm{ds}}=R_s{i}_{\mathrm{ds}}+\frac{{\mathrm{d\ψ}}_{\mathrm{ds}}}{\mathrm{dt}}-{\mathrm{\ω}}_e{i}_{\mathrm{qs}}{L}_{\mathrm{ls}}-{\mathrm{\ω}}_e{i}_{\mathrm{qm}}{L}_m=R_s{i}_{\mathrm{ds}}+\frac{{\mathrm{d\ψ}}_{\mathrm{ds}}}{\mathrm{dt}}-{\mathrm{\ω}}_e{\mathrm{\ψ}}_{\mathrm{qs}}---\left(1\right)$

$v_{\mathrm{qs}}=R_s{i}_{\mathrm{qs}}+\frac{{\mathrm{d\ψ}}_{\mathrm{qs}}}{\mathrm{dt}}+{\mathrm{\ω}}_e{i}_{\mathrm{ds}}{L}_{\mathrm{ls}}+{\mathrm{\ω}}_e{i}_{\mathrm{dm}}{L}_m=R_s{i}_{\mathrm{qs}}+\frac{{\mathrm{d\ψ}}_{\mathrm{qs}}}{\mathrm{dt}}+{\mathrm{\ω}}_e{\mathrm{\ψ}}_{\mathrm{ds}}---\left(2\right)$

i _ds+i _dr＝i _dm+i _dfe (3)

(5)

i _qs+i _qr＝i _qm+i _qfe

ψ _ds＝i _dsL _ls+i _dmL _m (6)

ψ _qs＝i _qsL _ls+i _qmL _m (7)

ψ _dr＝i _drL _ls+i _dmL _m (8)

ψ _qr＝i _qrL _ls+i _qmL _m (9)

$T_e=\frac{3}{2}\left(\frac{p}{2}\right)\left(\frac{L_m}{L_r}\right)[{\mathrm{\ψ}}_{\mathrm{dr}}(i_{\mathrm{qs}}-i_{\mathrm{fe}})-{\mathrm{\ψ}}_{\mathrm{qr}}(i_{\mathrm{ds}}-i_{\mathrm{dfe}})]---\left(10\right)$

These expression formulas have provided the induction machine model of considering iron loss, wherein L _mBe the motor mutual inductance, L _sThe motor stator inductance, L _rBe inductor rotor, L _LsBe the motor leakage inductance, R _sBe motor stator resistance, R _FeBe equivalent iron loss resistance, p is the motor pole number, ω _eBe synchronous angular velocity, T _eBe motor output torque, ψ _DsAnd ψ _QsAnd ψ _DrAnd ψ _QrBe respectively stator magnetic flux and the rotor flux under the d-q coordinate system, i _DsAnd i _Qs, i _DrAnd i _Qr, i _DmAnd i _QmAnd i _DfeAnd i _QfeBe respectively stator current, rotor current, exciting current and the iron loss equivalent current under the d-q coordinate system.Ignoring under the situation of iron loss, i.e. R _Fe=+∝, i _Dfe=0 and i _Qfe, just obtain conventional rotors field orientation vector control algorithm at=0 o'clock according to following formula.Therefore, comprise iron loss the d-q coordinate system under equivalent electric circuit have more versatility.

2) expression formula that induction machine is comprised iron loss is changed, and obtains its vector control method.

Further conversion can obtain following relation to above-mentioned formula:

${\mathrm{\ψ}}_{\mathrm{dr}}+\frac{L_{\mathrm{lr}}}{R_r}\frac{{\mathrm{d\ψ}}_{\mathrm{dr}}}{\mathrm{dt}}=L_m{i}_{\mathrm{dm}}---\left(11\right)$

${\mathrm{\ω}}_{\mathrm{sl}}=\frac{L_m{R}_r}{L_{\mathrm{lr}}}\frac{i_{\mathrm{qm}}}{{\mathrm{\ψ}}_{\mathrm{dr}}}---\left(12\right)$

$\frac{L_r}{L_{\mathrm{lr}}}{i}_{\mathrm{dm}}+\frac{L_m}{R_{\mathrm{fe}}}\frac{{\mathrm{di}}_{\mathrm{dm}}}{\mathrm{dt}}=i_{\mathrm{ds}}+\frac{{\mathrm{\ψ}}_{\mathrm{dr}}}{L_{\mathrm{lr}}}+\frac{L_m}{R_{\mathrm{fe}}}{\mathrm{\ω}}_e{i}_{\mathrm{qm}}---\left(13\right)$

$\frac{L_r}{L_{\mathrm{lr}}}{i}_{\mathrm{qm}}+\frac{L_m}{R_{\mathrm{fe}}}\frac{{\mathrm{di}}_{\mathrm{qm}}}{\mathrm{dt}}=i_{\mathrm{qs}}-\frac{L_m}{R_{\mathrm{fe}}}{\mathrm{\ω}}_e{i}_{\mathrm{dm}}---\left(14\right)$

In the indirect rotor field-oriented control system, has following relation: ψ _Dr=L _mi _Dm,

In its substitution above-mentioned relation formula, can be able to down relation:

$i_{\mathrm{ds}}=i_{\mathrm{dm}}-\frac{L_m}{R_{\mathrm{fe}}}{\mathrm{\ω}}_e{i}_{\mathrm{qm}}---\left(15\right)$

$i_{\mathrm{qs}}=\frac{L_m}{R_{\mathrm{fe}}}{\mathrm{\ω}}_e{i}_{\mathrm{dm}}+\frac{L_r}{L_{\mathrm{lr}}}{i}_{\mathrm{qm}}---\left(16\right)$

Comprehensive above the analysis can obtain considering that the indirect rotor orientation governing equation of induction machine under the iron loss situation is:

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{dr}}=L_m{i}_{\mathrm{dm}}\\ {\mathrm{\ω}}_{\mathrm{sl}}=\frac{1}{T_{\mathrm{lr}}}\frac{i_{\mathrm{qm}}}{i_{\mathrm{dm}}}\\ T_e=\frac{3}{2}\left(\frac{p}{2}\right)\left(\frac{L_m^2}{L_{\mathrm{lr}}}\right)i_{\mathrm{dm}}{i}_{\mathrm{qm}}\\ i_{\mathrm{ds}}=i_{\mathrm{dm}}-T_{\mathrm{fe}}{\mathrm{\ω}}_e{i}_{\mathrm{qm}}\\ i_{\mathrm{qs}}=T_{\mathrm{fe}}{\mathrm{\ω}}_e{i}_{\mathrm{dm}}+\frac{L_r}{L_{\mathrm{lr}}}{i}_{\mathrm{qm}}\end{array}\right.---\left(17\right)$

Wherein, $T_{\mathrm{Lr}}=\frac{L_{\mathrm{Lr}}}{R_r},$ $T_{\mathrm{Fe}}=\frac{L_m}{R_{\mathrm{Fe}}}.$

3) because i _QmValue very little, therefore be unfavorable for the realization of adjuster, order

Then the vector control equation is transformed to:

$\left\{\begin{array}{c}{\mathrm{\ψ}}_{\mathrm{dr}}=L_m{i}_{\mathrm{dm}}\\ {\mathrm{\ω}}_{\mathrm{sl}}=\frac{1}{T_r}\frac{i_{\mathrm{qm}}^{\′}}{i_{\mathrm{dm}}}\\ T_e=\frac{3}{2}\left(\frac{p}{2}\right)\left(\frac{L_m^2}{L_{\mathrm{lr}}{L}_r}\right)i_{\mathrm{dm}}{i}_{\mathrm{qm}}^{\′}\\ i_{\mathrm{ds}}=i_{\mathrm{dm}}-\frac{L_{\mathrm{lr}}}{L_r}{T}_{\mathrm{fe}}{\mathrm{\ω}}_e{i}_{\mathrm{qm}}^{\′}\\ i_{\mathrm{qs}}=T_{\mathrm{fe}}{\mathrm{\ω}}_e{i}_{\mathrm{dm}}+i_{\mathrm{qm}}^{\′}\end{array}\right.---\left(18\right)$

According to this equation, can obtain considering the indirect rotor field-oriented control method of iron loss.Compare with the conventional vector control mode, just on current regulator, increased by two iron loss compensation term:

And T _Feω _ei _DmIt realizes that block diagram is as shown in Figure 1; It comprises rotating speed pi regulator 1, torque current pi regulator 2, exciting current controller 3, output voltage Park inverse transformation (2/3 conversion) module 4; Space vector SVPWM module 5, inverter 6, current sample and processing module 7, stator current Clark conversion (3/2 conversion) module 8, electric current Park conversion module 9, field orientation module 10, induction machine 11.

According to motor given rotating speed n _RefWith real-time feedback speed n, obtain velocity deviation; Velocity deviation obtains torque current set-point i ' through speed pi regulator 1 _Qm, the value i after this electric current and the current feedback decoupling zero _Qs, and torque current iron loss compensation term T _Feω _ei _DmConstitute the input of torque current pi regulator 2 together, it is output as q shaft voltage set-point v _QsExciting current set-point i _DmWith the value i after the current feedback decoupling zero _Ds, and exciting current iron loss compensation term

Constitute the input of exciting current pi regulator 3, it is output as d shaft voltage set-point v _DsThrough Park inverse transform block 4, with v _QsAnd v _DsBe transformed to the component of voltage v under the two phase rest frames _{α s}And v _{β s}Voltage v _{α s}And v _{β s}Through SVPWM module 5,6 road pwm signals that output inverter 6 is required, through the switch of power device in the inverter 6, the voltage of control motor 11 stator side; Obtain three-phase current i through current sensor and current signal processing module 7 _a, i _bAnd i _c, three-phase current obtains the component i under the two phase rest frames through Clark conversion module 8 _{α s}And i _{β s}Then, through Park conversion module 9, and combined magnetic field orientation module 10 resulting rotor field angle θ _e, obtain the current component i under the rotating coordinate system _DsAnd i _QsI ' through speed feedback n and the influence of consideration iron loss _QmAnd i _Dm, obtain rotor field angle θ through field orientation module 10 _e

Fig. 3 has provided the Physical Experiment waveform.Fig. 3 (a) figure is 0-8000 rev/min velocity step experiment, adopts iron loss compensation post acceleration characteristic obviously to strengthen.If iron loss has been carried out effective compensation, and the given i of field supply _DmBe inversely proportional to speed, then when the empty load of motor weak magnetic field operation, along with the rising of rotating speed, it is constant that motor lines voltage keeps; If compensation is inaccurate or uncompensated, then, cause line voltage and speed line sexual intercourse not to exist because field orientation is inaccurate and true field does not conform to given; Therefore, in order to examine the accuracy of compensation, compensation and uncompensated two kinds of situation are contrasted; Fig. 3 (b) figure is a comparative result; Wherein (*) is depicted as the effect after iron loss compensates, and can know that by figure voltage keeps constant basically along with rotating speed rises, and explains that the iron loss compensation has obtained expected effect; And (●) is depicted as the waveform that does not have compensation, and voltage and speed do not have linear relationship.

The present invention is through comprising the induction machine equivalent electric circuit of iron loss; Derivation obtains the iron loss compensation term of torque current and exciting current; And on the basis of conventional vector control method; Torque current and field supply are compensated, thereby in rotor field-oriented angle calculation process, can consider the influence of iron loss, and then improve the precision of field orientation.And in the changes of magnetic field process, during like the above weak magnetic field operation of motor base speed, can guarantee that the magnetic field size that true field and drive system require is consistent.

Claims (1)

1. induction Motor Vector Control method of considering iron loss; Two closed-loop controls of employing speed outer shroud and current inner loop, speed outer shroud adopt motor speed PI to regulate control, and it is output as the torque current command value of current inner loop; Current inner loop adopts walk around square electric current and field supply PI adjusting control; It is characterized in that, in current inner loop, respectively torque current and field supply are compensated; And in torque current after will compensating and the adjusting of field supply component introducing current PI, the iron loss compensation term of torque current and field supply is respectively

And T _Feω _ei _Dm, wherein, L _rBe the rotor inductance, L _LrBe the rotor leakage inductance,

L _mBe the motor mutual inductance, R _FeBe motor equivalence iron loss resistance,

ω _eBe synchronous angular velocity, i _DmAnd i _QmBe respectively d axle and q axle excitation current component.

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