CN105720877B - On-line parameter identification method based on three phase alternating current motor equivalent circuit - Google Patents

Abstract

The invention discloses a kind of on-line parameter identification methods based on three phase alternating current motor equivalent circuit, have following steps：The stator voltage and stator current of the three phase alternating current motor of normal operation are acquired, by establishing α β coordinate systems, is converted to stator voltage vectorAnd stator current vectorDq rotating coordinate systems are established, the stator voltage vector that will be obtainedThe d axis of definition in a coordinate system；Obtain the excitation current vector L of the three phase alternating current motor_μ, equivalent leakage inductance L_σWith power supply angular frequency_eThe initial value of equivalent rotor voltage vector is acquired according to formulaWith equivalent rotor fluxIn the dq rotating coordinate systems, according to voltage vectorWith stator resistance R_sVariation, will move along the straight line p1 parallel with current phasor；The stator current vectorThe current phasor initial value resolved intoIt will be moved along the straight line p2 vertical with stator current vector；By formula, rotor equivalent resistance R is calculated_rref；By formula, motor stator resistance R is obtained_s。

Description

Parameter online identification method based on three-phase alternating current motor equivalent circuit

Technical Field

The invention belongs to the field of three-phase alternating current motor control, and particularly relates to a parameter online identification method based on an equivalent circuit of a three-phase alternating current motor, which can be applied to the fields of electric locomotives, diesel locomotives, electric automobiles and the like. To the patent classification number G01 measurement; test G01R measures an electrical variable; the means for measuring the magnetic variable G01R27/00 measures the resistance, reactance, impedance or a derivative thereof G01R27/02 resistance, reactance, impedance or other derivative thereof across a property, such as a real or complex measurement of a time constant.

Background

At present, the directional vector control of the rotor magnetic field becomes a commonly adopted control scheme in the field of alternating current motor control. The scheme is based on an alternating current motor mathematical model, and realizes decoupling control of alternating current motor excitation and torque through mathematical transformation, thereby improving static and dynamic performances. However, the performance improvement is based on accurate acquisition of motor parameters, and a steady-state equivalent circuit of the motor is shown in fig. 1, wherein particularly the rotor resistance Rrref changes with the change of the motor temperature, and if the change of the rotor resistance is not corrected or compensated to a certain extent in the control process, the control dynamic performance and the system efficiency are greatly reduced. Therefore, if motor parameters, particularly rotor resistance, can be identified on line in the control process, the overall performance of the motor control system is undoubtedly improved.

The motor rotor resistance online identification method can be roughly divided into three categories: firstly, motor parameters are calculated by injecting special signals into the motor and detecting voltage or current response, and the method can generate certain disturbance for the motor which is stably running in real time; secondly, based on a motor equation, a Kalman filter or a Longbeige filter is used for estimating parameters, and the method has large complex calculation amount; and thirdly, identifying parameters by using regulators by establishing mathematical models with the same physical meaning but different expression modes based on a model reference self-adaptive method, wherein the method is simple, an additional regulator needs to be added, and the rest motor parameters are known.

Disclosure of Invention

The invention provides a parameter online identification method based on an equivalent circuit of a three-phase alternating current motor aiming at the problems, which comprises the following steps:

acquiring the stator voltage and the stator current of a normally operating three-phase alternating current motor, and converting the stator voltage and the stator current into a stator voltage vector by establishing an αβ coordinate systemAnd stator current vector

-establishing a dq-rotation coordinate system,the obtained stator voltage vectorDefining a d-axis in a coordinate system; obtaining an excitation current vector I of the three-phase AC motor_μEquivalent leakage inductance L_σEquivalent excitation inductance L_μAnd synchronous angular frequency omega_eAccording to the formula:

determining an initial value of an equivalent rotor voltage vectorAnd equivalent rotor flux linkage

-according to the initial value of the voltage vector in said dq rotating coordinate systemStator-following resistor R_sWill follow the stator current vectorThe parallel straight line p1 moves; the stator current vectorDecomposed current vector initial valueWill move along a line p2 perpendicular to the stator current vector; at the same time, the stator current vector is establishedA circle c2 with the center point S as the center of the circle and the diameter of the die; the intersection point of the straight line p2 and the circle c2 is obtained, and the current vector is obtained according to the vector relation

-by means of the formula,

calculating to obtain equivalent resistance R of rotor_rrefWherein

Ψ_rmode, ω, representing equivalent rotor flux linkage_rRepresenting the motor speed;

-by means of the formula,

obtaining the motor stator resistance R_s。

In a preferred embodiment, the stator voltage vector isCalculated by the following formula:

j is U_smaxA component on an imaginary axis in the dq coordinate system;is the initial phase of the voltage;

U_smaxby defining under said αβ coordinate system:

U_smaxthe acquired voltage amplitude is acquired; omega_eFor synchronizing the angular frequency, u_sαComponent of voltage on axis α u_sβIs the component of the voltage on the coordinate axis β.

As a preferred embodiment, the method for online identification of parameters based on an equivalent circuit of a three-phase alternating current motor is further characterized in that the stator current vectorCalculated by the following formula:

I_sdis the projection of the stator current on the d axis; i is_sqIs the projection of the stator current on the q axis; j is U_smaxA component on an imaginary axis in the dq coordinate system, which represents a unit vector in the q-axis direction;

through I_smaxDefined under the αβ coordinate system

Wherein i_sαComponent, i, of current in coordinate axis α_sβComponent of current in coordinate axis β_smaxAmplitude of the current, omega_eIn order to synchronize the angular frequency of the signal,is the initial phase of the current;

the I can be obtained by coordinate conversion through the included angle theta of the αβ coordinate system and the dq rotation coordinate system_sdAnd I_sq。

In a preferred embodiment, the equation of the straight line p2 is:

q＝q₀+K_p2*(d-d₀) (1)

wherein,K_p2is the slope of line P2;

wherein d is the excitation current vectorProjection on the d-axis, d₀As vector of exciting currentInitial values of the projection on the d-axis; q is an excitation current vectorProjection on the q-axis, q₀As vector of exciting currentAn initial value of the projection on the q-axis;

-defining one in a rotating coordinate system dqA circle c2 with its center point S as the center of the circle having the diameter of (a);

wherein d is_sAs stator current vectorA projection of the midpoint of (a) on the d-axis in the rotating coordinate system, q_sStator current vectorA projection of the midpoint of (a) onto the q-axis in the rotating coordinate system;

make the excitation current vectorHas the coordinates of (d)_A，q_A)；

The equations (1) and (2) are combined to obtain an equation system of the intersection point of the straight line p2 and the circle c2, and the solution is obtained by:

q_A1,2＝q₀+K_p2*(d_A1,2-d₀)

wherein,

the positional relationship in the coordinate system is incorporated.

By adopting the technical scheme, the parameter online identification method based on the equivalent circuit of the three-phase alternating current motor disclosed by the invention is completely based on the equivalent circuit of the motor, has clear physical concept, and only needs to acquire voltageElectric currentSupply angular frequency omega_eRotational speed omega_rCombined with known motor total leakage inductance L_σAnd equivalent excitation inductance L_μThe stator and rotor resistances can be solved by simple calculation.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 shows a steady-state equivalent circuit of a motor corresponding to vector control

FIG. 2 is R_sVector diagram corresponding to equivalent circuit when 0

FIG. 3 is R_sVector diagram corresponding to equivalent circuit when changing from zero

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the following describes the technical solutions of the embodiments of the present invention clearly and completely with reference to the accompanying drawings in the embodiments of the present invention:

as shown in fig. 1-3, assuming normal operation of the motor, the fundamental input voltage, the stator current and the stator voltage can be defined as follows under the αβ coordinate system:

wherein, U_smaxIs the voltage amplitude, I_smaxAmplitude of the current, omega_eIn order to synchronize the angular frequency of the signal,is the initial phase of the voltage (current), u_sαComponent of voltage on coordinate axis α, u_sβComponent of voltage on axis β, i_sαComponent, i, of current in coordinate axis α_sβThe component of the current in coordinate axis β.

Define dq rotation coordinate system, which is defined by omega_eRotate in speed and orient the q-axis at the input voltage vectorThe location of the same.

j is U_smaxThe component on the imaginary axis in the dq coordinate system.

αβ and dq can be obtained by the following formula,

after theta is present, the coordinate transformation can be used for obtaining

I_sdIs the projection of the stator current on the d axis; i is_sqIs the projection of the stator current on the q axis, j is U_smaxThe component on the imaginary axis in the dq coordinate system.

In connection with FIG. 2, assume R_sIs 0, knownL_μ、L_σAnd ω_eThen there is

L_μIs an equivalent excitation inductance; l is_σIn order to be equivalent to the leakage inductance,is the initial value of the equivalent rotor voltage vector,equivalent rotor flux linkage.

With R_sThe voltage drop of which is to be taken into account,will be along a straight line p parallel to the current vector₁The movement is carried out in such a way that,will be along a straight line p₂Move and finally fall at point a. Let the equation for the line P2 perpendicular to the stator current vector be:

q＝q₀+K_p2*(d-d₀) (7)

wherein,

c2 is such thatIs a diameter, a circle centered at its center point S, let the equation of c2 be

Wherein,

wherein d is the excitation current vectorProjection on the d-axis, d₀As vector of exciting currentInitial values of the projection on the d-axis; q is an excitation current vectorProjection on the q-axis, q₀As vector of exciting currentAn initial value of the projection on the q-axis;

order toHas the coordinates of (d)_A，q_A)，

Simultaneous equations (7) and (8) yield a system of equations for the intersection of p2 and c2, solved for the system of equations for the unknown variables d and q:

kp2 is the slope of line P2.

Wherein,

with reference to FIGS. 1 and 3, there are

Given the angular frequency ω of the motor supply_eAnd motor speed omega_rThen the slip angular frequency ω_sIs composed of

ω_s＝ω_e-ω_r(12)

Rotor equivalent resistance R_rrefCan be obtained by the following formula,

motor stator resistor R_sIt can be calculated as follows,

the method has clear physical concept and only needs to know the voltageElectric currentSupply angular frequency omega_eRotational speed omega_rCombined with known motor total leakage inductance L_σAnd equivalent excitation inductance L_μThe calculation of the stator and rotor resistances can be completed.

The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art should be considered to be within the technical scope of the present invention, and the technical solutions and the inventive concepts thereof according to the present invention should be equivalent or changed within the scope of the present invention.

Claims (4)

1. A parameter online identification method based on an equivalent circuit of a three-phase alternating current motor is characterized by comprising the following steps:

acquiring the stator voltage and the stator current of a normally operating three-phase alternating current motor, and converting the stator voltage and the stator current into a stator voltage vector by establishing an αβ coordinate systemAnd stator current vector

-establishing a dq rotation coordinate system, the stator voltage vector to be obtainedDefining a d-axis in a coordinate system; obtaining an excitation current vector I of the three-phase AC motor_μEquivalent leakage inductance L_σEquivalent excitation inductance L_μAnd synchronous angular frequency omega_eAccording to the formula:

determining an initial value of an equivalent rotor voltage vectorAnd equivalent rotor flux linkage

-according to the initial value of the voltage vector in said dq rotating coordinate systemStator-following resistor R_sWill follow the stator current vectorThe parallel straight line p1 moves; the stator current vectorDecomposed current vector initial valueWill move along a line p2 perpendicular to the stator current vector; at the same time, the stator current vector is establishedA circle c2 with the center point S as the center of the circle and the diameter of the die; the intersection point of the straight line p2 and the circle c2 is obtained, and the current vector is obtained according to the vector relation

-by means of the formula,

calculating to obtain equivalent resistance R of rotor_rrefWherein

Ψ_rmode, ω, representing equivalent rotor flux linkage_rRepresenting the motor speed;

-by means of the formula,

obtaining the motor stator resistance R_s。

2. The method according to claim 1, wherein the stator voltage vector is a vector of a three-phase alternating current motor equivalent circuitCalculated by the following formula:

j is U_smaxA component on an imaginary axis in the dq coordinate system;is the initial phase of the voltage;

U_smaxby defining under said αβ coordinate system:

U_smaxthe acquired voltage amplitude is acquired; omega_eFor synchronizing the angular frequency, u_sαComponent of voltage on axis α u_sβIs the component of the voltage on the coordinate axis β.

3. The method according to claim 2, wherein the stator current vector is a vector of a stator currentCalculated by the following formula:

I_sdis the projection of the stator current on the d axis; i is_sqIs the projection of the stator current on the q axis; j is U_smaxA component on an imaginary axis in the dq coordinate system, which represents a unit vector in the q-axis direction;

through I_smaxDefined under the αβ coordinate system

Wherein i_sαComponent, i, of current in coordinate axis α_sβComponent of current in coordinate axis β_smaxAmplitude of the current, omega_eIn order to synchronize the angular frequency of the signal,is the initial phase of the current;

the I can be obtained by coordinate conversion through the included angle theta of the αβ coordinate system and the dq rotation coordinate system_sdAnd I_sq：

4. The method according to claim 1, wherein the equation of the straight line p2 is:

q＝q₀+K_p2*(d-d₀) (1)

wherein,K_p2is the slope of line P2;

wherein d is the excitation current vectorProjection on the d-axis, d₀As vector of exciting currentInitial values of the projection on the d-axis; q is an excitation current vectorProjection on the q-axis, q₀As vector of exciting currentAn initial value of the projection on the q-axis;

-defining one in a rotating coordinate system dqA circle c2 with its center point S as the center of the circle having the diameter of (a);

wherein d is_sAs stator current vectorA projection of the midpoint of (a) on the d-axis in the rotating coordinate system, q_sStator current vectorA projection of the midpoint of (a) onto the q-axis in the rotating coordinate system;

make the excitation current vectorHas the coordinates of (d)_A，q_A)；

The equations (1) and (2) are combined to obtain an equation system of the intersection point of the straight line p2 and the circle c2, and the solution is obtained by:

q_A1,2＝q₀+K_p2*(d_A1,2-d₀)

wherein,

positional relationship incorporated in the coordinate system: