KR101981682B1 - Induction motor for estimating mutual inductance and rotor resistance and method for estimating thereof - Google Patents

Abstract

Disclosed is a method for estimating mutual inductance and rotor resistance of an induction motor. The estimation method comprises the steps of: allowing a magnetic flux estimator including a voltage model and a current model to receive a rotor angular velocity, a stator current, and a stator voltage and to estimate a voltage model rotor flux and a current model rotor flux; calculating an error between the estimated voltage model and current model rotor flux; and estimating mutual inductance and rotor resistance based on the calculated error between the flux. The step of calculating the error converts a function for the voltage model and current model rotor flux into a rotor coordinate system and calculates the error by converting the converted function into an error function separated from mutual inductance components and rotor resistance components based on the converted function for the voltage model and current model rotor flux.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an induction motor for estimating mutual inductance and rotor resistance,

The present invention relates to an induction motor for estimating mutual inductance and rotor resistance and an estimation method therefor. More particularly, the present invention relates to an induction motor for estimating mutual inductance and rotor resistance using magnetic flux information of a magnetic flux estimator, and an estimation method thereof.

A device that converts electric energy into dynamic energy by using the power that a current carrying conductor receives in a magnetic field is called an electric motor. The electric motor is classified into a DC motor and an AC motor according to the type of power source. AC motors can be classified into induction motors and permanent magnet synchronous motors using permanent magnets. In the past, due to the lack of power electronics technology and the ease of speed and torque control, DC motors were used in the past as variable-speed motors, but the necessity of regular maintenance of the brushes and commutators of DC motors, The use of AC motors is increasing due to structural problems such as limitation of number of motors.

As theories for the development of inverters, the development of advanced hardware in microprocessors and the interpretation of AC systems have been developed, the control of induction motors has become easier, and in recent years, Is widely used in the field.

When the flux-oriented control with coordinate conversion is used to control the induction motor, instantaneous torque control of the induction motor is possible. Therefore, by using the rotor flux reference control, the induction motor is widely used in fields requiring precise variable speed control and torque control.

Accurate setting of parameter constants is required to design the controller using the flux reference control of the induction motor. If the parameter constant is set incorrectly, the gain of the controller can also be designed incorrectly. If the controller gain is designed incorrectly, the performance of the motor may be degraded.

In order to use the flux-based control of the induction motor described above, flux information is required. The flux information is not measured in the hardware device but can be generally estimated in the controller. An accurate parameter constant is also required in the manner in which the flux is estimated in the controller. Therefore, when there is a parameter error between the induction motor system and the controller, the controller estimates erroneous magnetic flux information, and the motor control capability may be greatly degraded due to erroneously estimated magnetic flux information.

The parameters of the induction motor can largely be divided into stator resistance, stator transient inductance, mutual inductance and rotor resistance. Identification of stator parameter constants, including stator resistance and stator transient inductance, is relatively easier than mutual inductance and rotor resistance. On the other hand, the measurement of mutual inductance and rotor resistance is relatively more difficult than stator parameters.

Specifically, an induction motor composed mostly of a magnetic body has a magnetic saturation characteristic, and therefore, a change in inductance may occur depending on the current magnitude. Further, as the heat is generated due to the iron loss, the temperature inside the electric motor can be raised during the operation of the electric motor, and the resistance can also be raised as the temperature inside the electric motor rises. Therefore, mutual inductance and rotor resistance can be varied during operation of the motor. Although the mutual inductance and the rotor resistance are varied, the mutual inductance and the rotor resistance are required to be accurately corrected. However, the mutual inductance and the rotor resistance vary substantially. As described above, There is a problem that it is difficult to accurately correct the resistance.

A problem to be solved by the present invention is to provide a method for independently estimating mutual inductance and rotor resistance, which are large and difficult to estimate constants, without hardware equipment.

According to an aspect of the present invention, there is provided a method for estimating mutual inductance and rotor resistance of an induction motor, including: obtaining a rotor angular velocity, a stator current, and a stator voltage using a magnetic flux estimator including a voltage model and a current model Estimating a voltage model rotor flux and a current model rotor flux; Calculating an error between the estimated voltage model and the current model rotor flux; And estimating the mutual inductance and the rotor resistance based on the error between the calculated magnetic fluxes, wherein the calculating the error includes calculating a function for the voltage model and the current model rotor flux And the error can be calculated by transforming the mutual inductance component and the rotor resistance component into an error function based on the converted voltage model and the function for the current model rotor flux.

The step of estimating the mutual inductance and the rotor resistance may estimate the mutual inductance and the rotor resistance in real time.

The error function may be a sum of a signal having passed through a low-pass filter having the mutual inductance component as a coefficient and a signal having passed through a high-pass filter having the rotor resistance component as a coefficient.

The step of estimating the mutual inductance and the rotor resistance may simultaneously estimate the mutual inductance component and the rotor resistance component of the error function using a cyclic least squares method.

The step of estimating the mutual inductance and the rotor resistance may calculate the compensation component of the mutual inductance and the rotor resistance to make the mutual inductance component and the rotor resistance component zero by the proportional integral controller.

Wherein the step of estimating the mutual inductance and the rotor resistance includes the steps of repeating the process of calculating the compensation component of the mutual inductance and the rotor resistance and calculating the mutual inductance and the rotor resistance based on the calculated mutual inductance and the compensation component of the rotor resistance, The estimation of the rotor resistance can be repeatedly updated.

According to an aspect of the present invention, there is provided an induction motor including a voltage model and a current model. The induction motor receives a rotor angular velocity, a stator current, and a stator voltage, A magnetic flux estimator for estimating a magnetic flux; And a controller for calculating an error between the estimated voltage model and the current model rotor flux, wherein the controller estimates the mutual inductance and the rotor resistance based on the error between the calculated magnetic fluxes, Model and the current model rotor flux into a rotor coordinate system and separating the mutual inductance component and the rotor resistance component based on a function for the converted voltage model and the current model rotor flux It is possible to calculate the error by converting it into an error function.

According to the embodiment of the present invention as described above, it is possible to simultaneously estimate the mutual inductance and the rotor resistance, which are difficult to estimate constants and have large fluctuations, and thus it is possible to effectively control the electric motor.

In addition, according to an embodiment of the present invention, there is no need for a separate hardware device for estimating mutual inductance and rotor resistance, and the algorithm structure is simple.

The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood to those of ordinary skill in the art from the following description.

1 is a flowchart illustrating a method of estimating mutual inductance and rotor resistance of an induction motor according to an embodiment of the present invention.
FIG. 2 illustrates a method of estimating mutual inductance and rotor resistance of an induction motor using the principle of model reference adaptive control according to an embodiment of the present invention.
FIG. 3 illustrates an overall process of estimating mutual inductance and rotor resistance of an induction motor according to an embodiment of the present invention.
FIG. 4 illustrates calculating the compensation component of mutual inductance and rotor resistance using a proportional integral controller in accordance with an embodiment of the present invention.
5 (a) and 5 (b) show the results of estimating the parameters under a given speed and load condition in the absence of stator parameter error.
Figs. 6 (a) and 6 (b) show the results of estimating the parameters under a given speed and load condition when there is an error in the stator parameters.
Figs. 7 (a) and 7 (b) show the results of estimating the parameters under a given speed and load condition when there is no error in the stator parameters while periodically varying the load coupled to the motor.
8 (a) and 8 (b) show the results of estimating the parameters at a given speed and load condition in the presence of errors in the stator parameters while periodically varying the load coupled to the motor.
9 is a block diagram illustrating an induction motor for estimating mutual inductance and rotor resistance according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS The advantages and features of the present invention and the manner of achieving them will become apparent with reference to the embodiments described in detail below with reference to the accompanying drawings. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Is provided to fully convey the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Unless defined otherwise, all terms (including technical and scientific terms) used herein may be used in a sense commonly understood by one of ordinary skill in the art to which this invention belongs. In addition, the notation of the parameters and parameters used in the present specification can be defined by the following Table 1. < tb > < TABLE > Also, commonly used predefined terms are not ideally or excessively interpreted unless explicitly defined otherwise.

v Voltage i electric current λ Magnetic flux w _r Rotor angular velocity s Differentiator Superscript Stationary coordinate system Superscript r Rotor coordinate system Superscript e Synchronous coordinate system Subscripts Stator Subscript r Rotor ^ Estimated value Bold Vector value R _s Stator resistance R _r Rotor resistance σL _s Stator transient inductance L _m Mutual inductance L _r Rotor self-inductance L _lr Rotor leakage inductance T _r Rotor Time Constant, L _r / R _r

The stationary reference frame used herein denotes a stationary reference frame in which the coordinate axis of the dq axis does not rotate and a reference frame of the rotor reference frame indicates a coordinate system in which the coordinate axes of the dq axis also rotate together at an angular velocity w And the synchronous reference frame represents a coordinate system in which the coordinate axis of the dq axis rotates at the frequency w _e of the three-phase current. The d axis represents the axis on which the flux of the motor is generated, and the q axis represents the axis perpendicular to the d axis and on which the torque is generated.

It is also to be understood that the expressions " first, " " second, ", etc. used herein may be used to denote various components, regardless of their order and / or importance, and to distinguish one component from another But is not limited to those components. For example, the first user equipment and the second user equipment may represent different user equipment, regardless of order or importance. For example, without departing from the scope of the rights described in this document, the first component may be named as the second component, and similarly the second component may be named as the first component.

As used herein, the expressions " have, " " comprise, " " comprise, " or " comprise may " refer to the presence of a feature (e.g., a numerical value, a function, And does not exclude the presence of additional features.

1 is a flowchart illustrating a method of estimating mutual inductance and rotor resistance of an induction motor according to an embodiment of the present invention.

1, in a mutual inductance and rotor estimation method of an induction motor according to an embodiment of the present invention, a magnetic flux estimator including a voltage model and a current model receives a rotor angular velocity, a stator current, and a stator voltage Voltage model rotor flux and current model rotor flux are estimated (S110).

The magnetic flux estimator of the induction motor can be divided based on the stator model and rotor model equations. The voltage model magnetic flux estimator based on the stator model can estimate the voltage model rotor flux in the stator coordinate system by receiving the stator voltage and the stator current. On the other hand, the current model flux estimator based on the rotor model can estimate the current model rotor flux in the stator coordinate system by receiving the rotor angular velocity and the stator current.

Voltage model estimation in the stator coordinate system The rotor flux can be expressed as the following equation (1).

(1)

(One)

Current model estimation in the stator coordinate system The rotor flux can be expressed by the following equation (2).

(2)

(2)

However, since the voltage model of Equation (1) includes a pure integral of 1 / s, an offset component problem may occur. Therefore, since the voltage model estimation rotor flux in the stator coordinate system can not be practically implemented as in Equation (1), a high finaness model such as the following Equation (3) can be used. The Gopinas model estimated rotor flux is a mixture of voltage model estimated rotor flux and current model estimated rotor flux.

(3)

(3)

Kp and Ki denote a proportional-integral controller (PI controller).

)를 통과시킨 형태 및 전류 모델 추정 회전자 자속에 저주파 통과 필터(LPF)(

)를 통과시킨 형태의 합으로 나타날 수 있다. 따라서, 주파수가 충분히 높은 고주파 영역대에서는 전압 모델 추정 회전자 자속이 대부분 출력될 수 있다. 따라서, 고피나스 모델이 이용되면, 상술한 옵셋 문제가 해결된 전압 모델이 구현될 수 있다.The high-pass model estimating rotor flux equation is based on the high-pass filter (HPF) (

) And the current model estimation rotor flux (LPF) (

) In the form of a line. Therefore, most of the voltage model estimation rotor flux can be output in the high frequency region band where the frequency is sufficiently high. Therefore, when a high finaness model is used, a voltage model in which the above-described offset problem is solved can be implemented.

In one embodiment of the present invention, a voltage model can be implemented using the characteristics of the high-fin-state model described above.

In the equation (1), the parameters used for the voltage model estimation rotor flux in the stator coordinate system estimated from the magnetic flux estimator receiving the stator voltage and stator current are stator resistance, stator transient inductance, mutual inductance and rotor magnetic inductance .

In equation (2), the parameters used in the current model estimation rotor flux in the stator coordinate system estimated from the magnetic flux estimator input the stator current and the rotor angular velocity are the rotor time constant including the rotor resistance and the rotor magnetic inductance And mutual inductance can be used.

As described above, since the parameters used in the voltage model estimation rotor flux and the parameters used in the current model estimation rotor flux are different, the estimated flux in each model can be different if there is a parameter error.

An error between the voltage model estimated from the magnetic flux estimator including the voltage model and the current model and the current model rotor flux is calculated (S120).

Specifically, the error calculations between the magnetic fluxes are performed such that the functions for the voltage model and the current model rotor flux are converted to the rotor coordinate system, and based on the converted voltage model and the function for the current model rotor flux, the mutual inductance component and the rotor resistance As the components are transformed into separate error functions, the error between fluxes can be calculated.

로 나타낼 수 있고, 일반적으로 상호 인덕턴스 대비 누설 인덕턴스가 매우 작으므로 식 (1)에 나타난

는 “1”로 가정될 수 있다. 따라서, 고정자 좌표계에서의 전압 모델 추정 회전자 자속은 상호 인덕턴스 및 회전자 저항의 오차가 존재하더라도, 고정자 저항 및 고정자 과도 인덕턴스가 정확한 경우 실질적으로 정확한 자속이 추정될 수 있다.The voltage model estimation rotor flux equation in the rotor coordinate system shown in equation (1) includes stator resistance and stator transient inductance. Meanwhile,

(1), because the leakage inductance is generally very small compared with the mutual inductance.

Can be assumed to be " 1 ". Thus, even if there is an error in the mutual inductance and the rotor resistance, the voltage model estimation rotor flux in the stator coordinate system can be estimated to be substantially accurate when the stator resistance and stator transient inductance are correct.

The mutual inductance and the rotor resistance of the induction motor can be estimated using the characteristics of the voltage model estimation rotor flux in the stator coordinate system according to an embodiment of the present invention.

The function for the current model estimation rotor flux in the stator coordinate system shown in equation (2) can be converted to a function for the current model estimation rotor flux in the rotor coordinate system. The function for the current model estimation rotor flux converted into the above-mentioned rotor coordinate system can be expressed by the following equation (4).

(4)

(4)

As described above, the voltage model estimation rotor flux in the stator coordinate system can be accurately estimated according to the value of the stator resistance and stator transient inductance despite the error of mutual inductance and rotor resistance. Further, as described above, the determination of the stator resistance and the stator transient inductance value is relatively easier than the mutual inductance and the rotor resistance. Therefore, using the above-described characteristics, the function for the voltage model estimation rotor flux in the stator coordinate system shown in equation (1) can be expressed as a function of the actual rotor resistance, the actual rotor self- inductance and the actual mutual inductance in the rotor coordinate system The current model can be equalized as a function of the estimated rotor flux. That is, the function of the voltage model estimation rotor flux in the rotor coordinate system estimated according to the stator resistance and the stator transient inductance value is expressed by the following equation (5) as the actual rotor resistance, the actual rotor self inductance and the actual mutual inductance Can be used as a function of the voltage model estimation rotor flux in the rotor coordinate system involved.

(5)

(5)

The error between the estimated voltage model and the current model rotor flux can be calculated by dividing the mutual inductance component and the rotor resistance component into separate error values by removing the stator current commonly contained in the function of the converted voltage model and the current model rotor flux, Function and can be calculated.

The above-described error function can be expressed as a sum of a signal that has passed through a low-pass filter having a mutual inductance component as a coefficient and a signal that has passed through a high-pass filter having a rotor resistance component as a coefficient.

The mutual inductance and the rotor resistance are estimated based on the error between the calculated magnetic fluxes (S130).

The mutual inductance and rotor resistance can be estimated in real time. That is, mutual inductance and rotor resistance can be estimated in real time even in a situation where the speed at which the motor actually operates is changed. Therefore, an embodiment of the present invention is also applicable to a motor system including a varying load.

Recursive Least Square may be used in the mutual inductance and rotor resistance estimation method based on the error between the magnetic fluxes calculated according to an embodiment of the present invention. By using the cyclic least squares method, the mutual inductance component and the rotor resistance component of the above-mentioned error function can be estimated at the same time.

Also, the mutual inductance and the rotor resistance can be calculated by using the proportional integral controller so that mutual inductance components and rotor resistance components simultaneously estimated by the cyclic least squares method become zero.

The process of calculating the compensation component of the mutual inductance and the rotor resistance can be repeated and the estimation of the mutual inductance and the rotor resistance can be repeatedly updated based on the compensation component of the calculated mutual inductance and rotor resistance.

FIG. 2 illustrates a method of estimating mutual inductance and rotor resistance of an induction motor using the principle of model reference adaptive control according to an embodiment of the present invention.

Referring to FIG. 2, the principle of model reference adaptive control (MRAC) may be applied to the method of estimating mutual inductance and rotor resistance of an induction motor according to an embodiment of the present invention. More specifically, the reference model receives a rotor angular velocity, a stator current, and a stator voltage, and calculates a high-frequency model rotor flux function estimated from a high-frequency model flux flux estimator in a high- Can be set as a function of the voltage model estimation rotor flux in the output rotor coordinate system. Also, the adaptive model can be set as a current model rotor flux in the rotor coordinate system estimated from the current model flux estimator, receiving the rotor angular velocity and the stator current. The magnetic fluxes estimated in the reference model and the adaptive model are compared in the adaptation mechanism so that the mutual inductance and rotor resistance of the induction motor can be estimated more accurately. In addition, the estimated mutual inductance and rotor resistance can be updated in a real-time adaptive model. The update of the estimated mutual inductance and rotor resistance can be updated based on the compensation components (? L _m ,? R _r ) of each of the mutual inductance and rotor components to be described later.

In the following, a method of estimating mutual inductance and rotor resistance of an induction motor by applying the above-described MRAS principle will be described. However, application of the MRAS is an example for illustrating an embodiment of the present invention, but is not limited thereto.

FIG. 3 illustrates an overall process of estimating mutual inductance and rotor resistance of an induction motor according to an embodiment of the present invention.

FIG. 4 illustrates calculating the compensation component of mutual inductance and rotor resistance using a proportional integral controller in accordance with an embodiment of the present invention.

3 and 4 will be described together.

Referring to FIG. 3, a magnetic flux estimator including a voltage model and a current model receives a rotor angular velocity, a stator current, and a stator voltage, and estimates a voltage model rotor flux and a current model rotor flux.

An error between the estimated voltage model rotor flux and the current model rotor flux can be calculated. The error calculations are based on the assumption that the function for the current model rotor flux is converted to the rotor coordinate system (see equation (4)) and the function for the voltage model rotor flux is converted to the rotor coordinate system (see equation (5) Based on the function of the voltage model (reference model) and the current model (adaptive model) rotor flux, the mutual inductance component and the rotor resistance component can be converted into separate error functions to calculate the error.

Specifically, the stator current can be canceled by the calculation of the equations (4) and (5), and the equation in which the stator current is canceled can be expressed as the following equation (6). In the equation below, Δλ represents the error between magnetic fluxes.

(6)

(6)

을 나타낸다.In the above formula (6)

.

에 의해

가 될 수 있다.Since the leakage inductance with respect to the mutual inductance is very small in the above-mentioned equation (6)

By

.

)가 통과된 신호 및 고역 통과 필터(

)가 통과된 신호의 합으로 나타낼 수 있다. 즉, 오차 함수는 상호 인덕턴스 성분을 계수로 하는 저역 통과 필터를 통과한 신호 및 회전자 저항 성분을 계수로 하는 고역 통과 필터를 통과한 신호의 합으로 나타낼 수 있다.Therefore, referring to Equation (7) below, the low-pass filter to the error between the magnetic flux reference model (voltage model) (λ _ref) (

) And a high-pass filter (

) Can be expressed as the sum of the signals passed through. That is, the error function can be expressed as a sum of a signal that passes through a low-pass filter having a mutual inductance component as a coefficient and a signal that has passed through a high-pass filter that has a rotor resistance component as a coefficient.

(7)

(7)

The mutual inductance component and the rotor resistance component are converted into separate error functions based on the function for the voltage model and the current model rotor flux converted into the rotor coordinate system by the above method, The error between the model and the current model rotor flux can be calculated.

The setting of the function for the voltage model estimation rotor flux can be set as a function of the voltage model estimation rotor flux in the rotor coordinate system output in the high frequency range where the frequency is sufficiently high in the high- have.

In the linear system, the input column vector X, the output y and the coefficient column vector A can be expressed by the following equation (8).

y = ^T A X (8)

The error between the voltage model estimated rotor flux and the current model estimated rotor flux converted into the rotor coordinate system can be set to the input column vector X and the output y through the input / output calculation.

The mutual inductance and the rotor resistance can be estimated based on the error between the magnetic fluxes. The reciprocal inductance component and the rotor resistance component of the error function can be estimated simultaneously by using the recursive least square method.

The cyclic least squares method according to an embodiment of the present invention can be used to minimize the weighted least squares error function with respect to the input signal by using various past data. Also, the forgetting factor can be used to determine how to reduce the impact of past data in calculating the covariance.

According to the cyclic least squares method using the forgetting factor, the coefficient can be estimated in real time as the following equation (9).

(9)

(9)

In the above equation (9), K represents a gain, e represents an error, P represents a covariance and? ₁ represents a forgetting factor, and λ ₁ represents a different value from the magnetic flux λ according to the embodiment of the present invention, .

The error Δλ between the magnetic fluxes in Eq. (7) can be applied to Eq. (8), and the input and output (X, y) and the coefficient A can be expressed as Eq.

,

]^T, A=[

,

]^T (10)y = ??, X = [

,

] ^T , A = [

,

] ^T (10)

,

)로부터 계산될 수 있다. 계산된 출력(y) 및 입력(X)이 식 (9)에 대입됨으로써 실시간으로 계수(A)가 추정될 수 있다. 본 발명의 일 실시 예로 계수 A=(

,

)일 수 있으며, 계수

및

는 아래의 식 (11)와 같이 나타낼 수 있다.In the above equation (10), the output (y) and the input (X) correspond to the magnetic flux estimators (? _{Ref ,? Adj} )

,

). ≪ / RTI > The coefficient A can be estimated in real time by substituting the calculated output y and the input X into the equation (9). In one embodiment of the present invention, the coefficient A = (

,

), And the coefficient

And

Can be expressed by the following equation (11).

,

(11)

,

(11)

The above-mentioned coefficient A is a formula for explaining an embodiment of the present invention, but is not limited thereto.

The reference model λ _ref and the adaptation model λ _adj expressed in Equation (7) according to an embodiment of the present invention may be a vector, and may be a vector simultaneously including a d-axis and a q-axis. Therefore, equation (7) can be satisfied in both the d-axis and the q-axis.

,

) 및 q축에서 추정된 계수를 산술 평균한 값이 사용되었다. 단, 상술한 예에서 사용된 산술 평균한 값은 본 발명의 일 실시 예를 설명하기 위한 것일 뿐 이에 한정되는 것은 아니다.In the method of estimating mutual inductance and rotor resistance of an induction motor according to an embodiment of the present invention,

,

) And the arithmetic mean of the coefficients estimated in the q-axis. However, the arithmetic mean value used in the above-described example is intended to illustrate an embodiment of the present invention, but is not limited thereto.

및

는 각각 상호 인덕턴스 성분 및 회전자 저항 성분의 오차율이 수반될 수 있다. 따라서,

및

가 0으로 제어됨으로써 유도전동기의 상호 인덕턴스 및 회전자 저항이 추정될 수 있다. 계수 제어기에 의해

및

가 0으로 제어될 수 있다.In the above-mentioned equation (11)

And

May each be accompanied by an error rate of the mutual inductance component and the rotor resistance component. therefore,

And

Is controlled to be zero, mutual inductance and rotor resistance of the induction motor can be estimated. By the coefficient controller

And

Lt; / RTI > can be controlled to zero.

Referring to FIG. 4, the coefficient controller may be a proportional integral controller. The compensation component of the mutual inductance and the rotor resistance for making the mutual inductance component and the rotor resistance component zero by the proportional integral controller can be calculated. The compensation component of the calculated mutual inductance may be? L _m , and the compensation component of the calculated rotor resistance may be? R _r .

Referring again to FIG. 3, in accordance with an embodiment of the present invention, the compensation inductance (ΔL _m , ΔR _r ) of the mutual inductance and rotor resistance output from the coefficient controller can be passed to the output filter. The output filter may be a low pass filter (LPF). Therefore, there is noise contained in the output from the coefficient control the mutual inductance of the electronic components and the time compensating resistance _(m ΔL, ΔR _r) can be removed.

According to one embodiment of the invention, the mutual inductance and the time compensating components of the electronic resistance in the output controller coefficient _(m ΔL, ΔR _r) each of which it can be updated as Equation (12) below.

,

(12)

,

(12)

와

는 각각 상호 인덕턴스 및 회전자 저항의 초기 설정값을 나타낸다.In the above-mentioned equation (12)

Wow

Respectively represent initial set values of mutual inductance and rotor resistance.

According to an embodiment of the present invention, the calculation process of the compensation component of mutual inductance and rotor resistance can be repeated, and the mutual inductance and the resistance of the rotor are estimated repeatedly based on the calculated compensation component of mutual inductance and rotor resistance. . ≪ / RTI >

Thus, even though the initial set values of mutual inductance and rotor resistance are erroneous values, the estimated values of mutual inductance and rotor resistance by the compensating component of each mutual inductance and rotor resistance output according to an embodiment of the present invention are accurate Lt; / RTI >

FIGS. 5 (a) to (b) show results of estimating mutual inductance and rotor resistance of an induction motor by using a simulation program according to an embodiment of the present invention.

Table 2 below shows the specifications of the induction motor. The simulation program used in Figs. 5 (a) to 8 (b) according to an embodiment of the present invention uses the specifications of the induction motor shown in Table 2 below. The present invention is not limited thereto.

Rated capacity 1.5 kW Number of poles 4 Rated speed 1455rpm Rated torque 9.2 N · m Stator resistance 1.67Ω Rotor resistance 0.73Ω Mutual inductance 137mH Stator transient inductance 12.7mH

The simulation program according to an embodiment of the present invention was tested under the conditions of speeds of 300, 600 and 1200 rpm, and the load torque was tested at 30, 50 and 80% of the induction motor rating. 5 (a) to 6 (b) show experiments in which the mutual inductance was set to 206 mH which is 1.5 times the actual value, and the initial value of the rotor resistance was set to 0.37 Ω which is 0.5 times the actual value. Figs. 7 (a) to 8 (b) show experiments in which the initial value of mutual inductance was set to 202.5 mH and the rotor resistance was set to 0.35 Ω.

The above-mentioned values are only illustrative for explaining one embodiment of the present invention, but the present invention is not limited thereto. The updated parameters are reflected in all controllers.

5 (a) and 5 (b) show the results of estimating the parameters under a given speed and load condition in the absence of stator parameter error.

FIG. 5 (a) shows parameter estimates of mutual inductance and rotor resistance and currents in the d and q axis of the synchronous coordinate system when a 50% load is applied at 600 rpm according to an embodiment of the present invention.

Referring to FIG. 5A, the values of the mutual inductance and the rotor resistance estimated according to an embodiment of the present invention are corrected, and the values of the currents in the synchronous coordinate system d and the q-axis are changed. The reason why the values of the currents in the d and q axes of the synchronous coordinate system are changed is that the gain of the controller fluctuates as the above two parameters are changed.

FIG. 5 (b) is a graph showing the relationship between the values of the mutual inductance and the rotor resistance estimated according to an embodiment of the present invention when the 50% load is applied at 600 rpm and the flux vector error is converged to '0' .

Referring to FIG. 5 (b), the flux vector error can be expressed by the following equation (13). The value of the magnetic flux vector error value is '0', which indicates that the magnetic flux error is '0' in both the d and q axes.

(13)

(13)

Figs. 6 (a) and 6 (b) show the results of estimating the parameters under a given speed and load condition when there is an error in the stator parameters. Specifically, the simulation results are obtained when the voltage model, which is a reference model according to an embodiment of the present invention, has a magnetic flux-to-flux error and a stator parameter error is present.

6A is a graph showing the relationship between the parameter estimates of the mutual inductance and the rotor resistance and the currents of the d and q axes in the synchronous coordinate system when an 80% load is applied at 300 rpm in the presence of stator resistance error. .

6 (b) shows the relationship between the parameter estimates of the mutual inductance and the rotor resistance, and the currents of the synchronous coordinate system d and q-axis when the 30% load is applied at 1200 rpm when there is an inductance error between the stator and the stator. .

6A and 6B, even when the stator resistance is 15% or the stator transient inductance is 25% smaller, the mutual inductance and the rotor resistance of the induction motor estimated according to the embodiment of the present invention, And converges to a value close to the actual value.

Table 3 below shows the results of estimating the parameter values of mutual inductance and rotor resistance according to a predetermined speed and predetermined load condition except when 80% load is applied at 300 rpm in FIG. 6 (a).

Table 4 below shows the results of estimating the parameter values of mutual inductance and rotor resistance according to predetermined speed and predetermined load condition except for a case where 30% load is applied at 1200rpm in FIG. 6 (b).

Referring to Table 3 below, the results of estimating the parameter values of the mutual inductance and the rotor resistance according to the predetermined speed and predetermined load condition when the stator resistance is 15% larger are shown. The final estimated values of mutual inductance and rotor resistance are expressed as a relative error (%) with respect to the parameters of the actual mutual inductance and rotor resistance.

According to the embodiment of the present invention, the estimated rotor resistance has a maximum error of 5%, and mutual inductance has a very small error of 6.7%.

speed
(rpm) Load (%) 30 50 80 R _r L _m R _r L _m R _r L _m 300 5.0 -2.7 1.7 -4.4 -0.7 -6.7 600 2.4 -1.5 0.8 -2.4 -0.5 -3.7 1200 1.2 -0.8 0.4 -1.3 -0.3 -2.0

Referring to Table 4 below, the results of estimating the parameter values of mutual inductance and rotor resistance according to predetermined speed and predetermined load condition when the stator inductance is 25% smaller are shown. The final estimated mutual inductance and rotor resistance values represent the relative error (%) of the actual mutual inductance and rotor resistance with respect to the parameters, and the same method as in Table 3 was used.

According to an embodiment of the present invention, the error of the estimated rotor resistance is 2.8% at maximum and the mutual inductance is 3.2% at maximum, even though the error of the stator transient inductance is 25% for the estimated rotor resistance. Is displayed.

speed
(rpm) Load (%) 30 50 80 R _r L _m R _r L _m R _r L _m 300
600
1200
2.5
0.6
2.6
-0.6
2.8
-3.2

Figs. 7 (a) and 7 (b) show the results of estimating the parameters under a given speed and load condition when there is no error in the stator parameters while periodically varying the load coupled to the motor.

FIG. 7 (a) shows parameter estimates of mutual inductance and rotor resistance and currents in the d and q axes of the synchronous coordinate system when a 50% load is applied at 600 rpm according to an embodiment of the present invention.

Referring to FIG. 7 (a), it can be seen that the estimated mutual inductance and rotor resistance parameters converge to actual values according to an embodiment of the present invention.

FIG. 7 (b) shows the value of the flux vector error when the 50% load is applied at 600 rpm and the mutual inductance and rotor resistance estimated according to the embodiment of the present invention are corrected.

Referring to FIG. 7 (b), it can be seen that the flux vector error converges to '0' as the estimated mutual inductance and rotor resistance parameters are corrected according to an embodiment of the present invention.

8 (a) and 8 (b) show the results of estimating the parameters at a given speed and load condition in the presence of errors in the stator parameters while periodically varying the load coupled to the motor. Specifically, the simulation results are obtained when the voltage model, which is a reference model according to an embodiment of the present invention, has a magnetic flux-to-flux error and a stator parameter error is present.

8 (a) is a graph showing the relationship between the parameter estimates of the mutual inductance and the rotor resistance and the currents in the synchronous coordinate system d and q-axis when the stator resistance is 15% .

8 (b) is a graph showing the relationship between the parameter estimates of the mutual inductance and the rotor resistance and the estimated values of the d and q axes of the synchronous coordinate system according to an embodiment of the present invention when the stator inductance is 25% Current.

8A and 8B, the parameters of the mutual inductance and the rotor resistance estimated according to an embodiment of the present invention include the stator resistance or stator transient inductance, It can be seen that all of the values converge to values close to the actual values without any significant difference from the results shown in (a) and (b).

However, the above-mentioned parameter values are only examples for explaining one embodiment of the present invention, and the present invention is not limited thereto.

The mutual inductance and rotor resistance estimation of the induction motor according to an embodiment of the present invention can be estimated without assuming steady state operation, so that it can be estimated even in a transient state operation.

In addition, the mutual inductance and rotor resistance estimation of an induction motor according to an embodiment of the present invention can be estimated also in a motor system having a fluctuating load. That is, the parameters can be corrected in real time even when the motor is actually in operation.

9 is a block diagram illustrating an induction motor for estimating mutual inductance and rotor resistance according to an embodiment of the present invention.

Referring to FIG. 9, an induction motor for estimating mutual inductance and rotor resistance includes a voltage model and a current model, receives a rotor angular velocity, a stator current, and a stator voltage and receives a voltage model rotor flux and a current model rotor flux And a controller 920 for calculating an error between the estimated voltage model and the current model rotor flux. The control unit 920 estimates mutual inductance and rotor resistance based on the error between the calculated magnetic fluxes, converts the functions of the voltage model and the current model rotor flux into a rotor coordinate system, The error can be calculated by converting the mutual inductance component and the rotor resistance component into an error function based on the function for the electromagnetic flux.

According to an embodiment of the present invention, the error function may be a sum of a signal having passed through a low-pass filter having a coefficient of mutual inductance as a coefficient and a signal having passed through a high-pass filter having a rotor resistance component as a coefficient.

The controller 920 according to an exemplary embodiment of the present invention may simultaneously estimate the mutual inductance component and the rotor resistance component of the error function using the cyclic least squares method. Also, the controller 920 may control the proportional integral controller to calculate the mutual inductance and the rotor resistance compensation component to make the mutual inductance component and the rotor resistance component zero. The controller 920 repeats the calculation process of the compensation component of the mutual inductance and the rotor resistance and repeatedly updates the estimation of the mutual inductance and the rotor resistance based on the calculated compensation component of the mutual inductance and the rotor resistance .

As described above, according to various embodiments of the present invention, since the mutual inductance component and the rotor resistance component can be separated, the mutual inductance component and the rotor resistance component of the induction motor can be simultaneously estimated. Therefore, there is an advantage that an effective control of the electric motor can be performed.

The mutual inductance and rotor resistance estimation method of the induction motor according to various embodiments described above can be implemented by a program and stored in various recording media. That is, a computer program that can be processed by the various control units to execute the various control methods described above can be used as stored in the recording medium.

Calculating an error between the estimated voltage model and the current model rotor flux, and calculating an error between the estimated voltage model and the current model rotor flux, Estimating the mutual inductance and the rotor resistance based on an error between the magnetic fluxes and calculating the error, the step of calculating an error includes: converting a function for the voltage model and the current model rotor flux into a rotor coordinate system, A program for performing error calculation by converting the mutual inductance component and the rotor resistance component into an error function based on a function of the voltage model and the current model rotor flux, transitory computer readable medium may be provided.

A non-transitory readable medium is a medium that stores data for a short period of time, such as a register, cache, memory, etc., but semi-permanently stores data and is readable by the apparatus. In particular, the various applications or programs described above may be stored on non-volatile readable media such as CD, DVD, hard disk, Blu-ray disk, USB, memory card, ROM,

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be construed as limiting the scope of the invention as defined by the appended claims. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention.

910: flux estimator
920:

Claims (7)

A method for estimating mutual inductance and rotor resistance of an induction motor,
A magnetic flux estimator including a voltage model and a current model receives a rotor angular velocity, a stator current, and a stator voltage and estimates a voltage model rotor flux and a current model rotor flux;
Calculating an error between the estimated voltage model and the current model rotor flux; And
And estimating the mutual inductance and the rotor resistance based on the error between the calculated magnetic fluxes,
Wherein the calculating the error comprises:
And converting the function of the voltage model and the current model rotor flux into a rotor coordinate system and outputting the mutual inductance component and the rotor resistance component based on the converted voltage model and the function for the current model rotor flux, The error is converted into a separated error function to calculate the error,
Wherein the error function comprises:
A signal passing through a low-pass filter of the voltage model rotor flux having the mutual inductance component as a coefficient, and a signal passing through a high-pass filter of the voltage model rotor flux having the rotor resistance component as a coefficient,
Wherein the step of estimating the mutual inductance and the rotor resistance comprises:
And estimating the mutual inductance component and the rotor resistance component of the error function simultaneously using a cyclic least squares method. The method according to claim 1,
Wherein the step of estimating the mutual inductance and the rotor resistance comprises:
And estimating the mutual inductance and the rotor resistance in real time. delete delete The method according to claim 1,
Wherein the step of estimating the mutual inductance and the rotor resistance comprises:
Wherein the compensating component of the mutual inductance and the rotor resistance for making the mutual inductance component and the rotor resistance component zero by the proportional integral controller is calculated. 6. The method of claim 5,
Wherein the step of estimating the mutual inductance and the rotor resistance comprises:
The inductance of the induction motor and the resistance of the rotor are repeated and the estimation of the mutual inductance and the rotor resistance is repeatedly updated based on the compensated component of the mutual inductance and the rotor resistance, Mutual inductance and rotor resistance estimation method. A magnetic flux estimator for estimating a voltage model rotor flux and a current model rotor flux including a voltage model and a current model and receiving a rotor angular velocity, a stator current, and a stator voltage; And
And a controller for calculating an error between the estimated voltage model and the current model rotor flux,
Wherein,
Estimating a mutual inductance and a rotor resistance based on an error between the calculated magnetic fluxes, converting a function for the voltage model and the current model rotor flux into a rotor coordinate system, The mutual inductance component and the rotor resistance component are converted into an error function by separating the mutual inductance component and the rotor resistance component based on a function for the electromagnetic flux to calculate the error, The resistance component is estimated at the same time,
Wherein the error function comprises:
A signal obtained by passing the low-pass filter of the voltage model rotor flux having the mutual inductance component as a coefficient, and a signal passing through the high-pass filter of the voltage model rotor flux having the rotor resistance component as a coefficient, Electric motor.

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