KR100636819B1 - A vector-control apparatus for a parallel induction motor - Google Patents

Abstract

The present invention relates to a vector control apparatus for a parallel induction motor, and more particularly, a torque and magnetic flux command / current converting unit for converting torque and magnetic flux commands into a direct current torque and a magnetic flux current; First and second subtractors for obtaining a difference between the torque and flux current value output from the torque and flux command / current converter and the actual torque and flux current value output from the synchronous coordinate converter; A PID controller which receives the torque and flux current difference signals output from the first and second subtractors and calculates a stator voltage through a proportional integral derivative; A stationary coordinate converter for converting the DC voltage command value of the stator output from the PID controller into an AC voltage command value; A 2/3 phase conversion unit for converting the two-phase AC voltage command value output from the still coordinate conversion unit into three phases; A pulse width modulated inverter for driving several induction motors connected in parallel by pulse width modulating the output voltage of the 2/3 phase converter; A 3/2 phase converter for converting the current output from the inverter into three phases into two phases; A synchronous coordinate converter converting the current output from the 3/2 phase converter into an actual torque and magnetic flux alternating current based on the rotor angular velocity; First and second differentiators for differentiating torque and magnetic flux current output from the torque and magnetic flux command / current converter; On the basis of the torque and the magnetic flux current output from the torque and the magnetic flux command / current converter, the derivative value of the torque and magnetic flux current differentiated through the first and second differentiators, and the DC voltage command value of the stator output from the PID controller. Synchronous angular velocity calculation unit for calculating the synchronous angular velocity through the formula determined by; The integrator is configured to calculate the rotor magnetic flux angle by integrating the synchronous angular velocity of the rotor output from the synchronous angular velocity calculator.

Therefore, in case of torque control operation in parallel induction motor vector control operation, the cost required for additionally installing the speed sensor to the motor can be reduced, and since the speed sensor is not installed, the influence of the speed sensor or the precision error can be eliminated. By not using the rotor resistance constant, the parallel induction motors can be controlled regardless of the temperature change of the motor.

Induction Motor, Vector Control, Synchronous Angular Speed, Rotor Magnetic Angle

Description

Modified vector control system for parallel control of induction motor {A vector-control apparatus for a parallel induction motor}             

1 is a block diagram of a conventional indirect vector control device for parallel control of a flow motor.

2 is a block diagram of an apparatus of the present invention.

Explanation of symbols on the main parts of the drawings

1: Torque and magnetic flux command / current converter 2, 3: 1st and 2nd subtractor

4,5: PID controller 6: Stop coordinate converter

7: 2/3 phase conversion unit 8: Pulse width modulation type inverter

9: 3/2 phase conversion unit 10: Synchronous coordinate conversion unit

14: integrator 15,16: first and second differentiator

17: synchronous angular velocity calculation unit

The present invention relates to a vector control apparatus for a parallel induction motor, and more particularly, to adopting a control method for obtaining a rotor magnetic flux angle without using a rotor resistance value, a stator resistance value and a motor speed, a parallel induction motor vector control operation. In the case of the time torque control operation, the invention was invented to reduce the cost required to additionally install the speed sensor to the motor and to remove the influence of the speed sensor defect or precision error.

In general, the vector control technique finds the rotor flux angle of the induction motor, and separates the stator current into the magnetic flux component and torque component, and independently controls the induction motor to have the same high control response characteristics as the DC motor.

In such a vector control method, direct vector control and indirect vector control are largely classified according to the method of obtaining the rotor magnetic flux angle.

When measuring the rotor flux angle directly, the information of the rotor flux is obtained through the Hall sensor or the flux measurement coil.In this case, the magnetic flux is distorted due to the saturation of the slot ripple and the magnetic path, and the magnetic flux measurement is inaccurate at low speed. Due to the problem that the installation of the hall sensor and the like is not easy, an indirect method of integrating a flux detector or calculating a slip speed and integrating the motor speed is widely used.

In the case of the indirect vector, the slip speed and the speed of the motor are required. When parallel driving is performed by the batch control method, the speed difference between the motors may occur due to the load imbalance between the motors and the sliding phenomenon.

In this case, since the rotor flux angle calculation is not performed correctly by the method of calculating the speed of the reference motor, vector control may not be performed properly, and thus the entire system may become unstable.

등가회로에서 다음과 같은 식으로 표현할 수 있다.First of all, the induction motor model

In an equivalent circuit, it can be expressed as

(식 1)

(Equation 1)

(식 2)

(Equation 2)

(식 3)

(Equation 3)

(식 4)

(Equation 4)

(식 5)

(Eq. 5)

(식 6)

(Equation 6)

(식 7)

(Eq. 7)

(식 8)

(Eq. 8)

: 동기 각속도,

: 회전자 각속도, here,

Synchronous angular velocity,

: Rotor angular velocity,

,

: q축, d축 고정자 전압,

,

: q축, d축 회전자 전압,

,

: q-axis, d-axis stator voltage,

,

: q-axis, d-axis rotor voltage,

,

: q축, d축 고정자 전류,

,

: q축, d축 회전자 전류

,

: q-axis, d-axis stator current,

,

: q-axis, d-axis rotor current

,

: q축, d축 고정자 자속,

,

: q축, d축 회전자 자속

,

: q-axis, d-axis stator flux,

,

: q-axis, d-axis rotor flux

, : 고정자 저항,

: 회전자 저항,

,: Stator resistance,

: Rotor resistance,

: 고정자 인덕턴스,

: 회전자 인덕턴스,

: 상호인덕터스 이다.

Stator inductance,

: Rotor inductance,

: Mutual inductance.

)를 산출하는 가산기(13)와; 상기 가산기(13)에서 출력되는 회전자의 동기각속도를 적분하여 회전자 자속각(

)을 산출해 내는 적분기(14)로 구성되어 있다.However, the conventional indirect vector control apparatus for parallel control of the conventional motor is a torque and magnetic flux command / current converter (1) for converting the torque and the magnetic flux command to the torque current and magnetic flux current of the direct current as shown in FIG. Wow; First and second subtractors for obtaining a difference between the torque and the magnetic flux current value output from the torque and the magnetic flux command / current converter 1 and the actual torque and the magnetic flux current value output from the synchronous coordinate converter 10 ( 2) (3); A PID (Proportional Integral Differential) controller (4) (5) which receives the torque and magnetic flux current difference signals output from the first and second subtractors (2) (3) and calculates a stator voltage through proportional integral derivatives; ; A stationary coordinate converter (6) for converting a DC voltage command value of the stator output from the PID controller (4) (5) into an AC voltage command value; A two-third-phase converter (7) for converting the two-phase AC voltage command value output from the stationary coordinate converter (6) into three-phase; A pulse width modulation (PWM) inverter (8) for driving a plurality of induction motors (IM1-IMn) connected in parallel by pulse width modulating the output voltage of the 2/3 phase conversion section (7); A 3/2 phase converter 9 for converting the current output from the inverter 8 into three phases into two phases; A synchronous coordinate converter (10) for converting the current output from the 3/2 phase converter (9) into an actual torque and magnetic flux alternating current based on the rotor angular velocity; A slip speed calculation unit (11) for calculating a degree of slip between the rotor and the internal magnetic flux of the induction motor based on the torque and the magnetic flux current output from the torque and the magnetic flux command / current converting unit (1); A reference speed calculator 12 for calculating an average speed of the several induction motors IM1-IMn; By summing the output values of the slip speed calculating section 11 and the reference speed calculating section 12, the synchronous angular velocity (

An adder 13 for calculating); Rotor magnetic flux angle by integrating the synchronous angular velocity of the rotor output from the adder 13

) Is composed of an integrator 14 for calculating.

The method of estimating the rotor flux angle in the conventional indirect vector control configured as described above is as follows.

,

는Rotor current in equations (5) and (6),

,

Is

(식 9)

(Eq. 9)

(식 10)

(Eq. 10)

,

를 제거하기 식(9), (10)을 대입하면,Rotor current in equations (3) and (4) above

,

If you substitute equations (9) and (10),

(식 11)

(Eq. 11)

(식 12)

(Eq. 12)

here

The conditional equation for non-interference control to classify torque component current and magnetic flux component current is

,

,

(식 13)

,

,

(Eq. 13)

 to be. In Eq. (12), Equation (14) is obtained using the non-interfering condition Equation (13).

(식 14)

(Eq. 14)

Using equation (13) which is a non-interference conditional expression in equation (11), the slip speed calculation equation (15) is obtained.

(식 15)

(Eq. 15)

If we reorganize the slip speed equation (15)

(식 16)

(Eq. 16)

In the reference speed calculation section 12, the calculation of the motor reference rotation speed is an average of the connected motor speeds.

(식 17)

(Eq. 17)

Where n is the number of motors connected in parallel.

It is calculated | required by slip speed plus motor reference rotational speed formula (17) like the rotation angle angular formula (18) calculated | required by the adder (13).

(식 18)

(Eq. 18)

Finally, the rotor flux angle integrated through the integrator 14 is obtained as shown in equation (19).

(식 19)

(Eq. 19)

)은 비간섭 제어시 조건으로 정리한 자속전류는 식(4)와 같이 주어진다.Magnetic flux current command of the magnetic flux relation equation of FIG.

) Is given by equation (4).

(식 20)

(Eq. 20)

Rated flux

(식 21)

(Eq. 21)

는 전동기 정격전압,

는 정격주파수이다.here

Motor rated voltage,

Is the rated frequency.

)Torque current command in the torque relationship equation of FIG.

)

(식 22)

(Eq. 22)

(식 23)

(Eq. 23)

Stator current command of Fig. 1

로 주어지는 자속각은 직교 단위벡터인

와

의 연산에 사용된다. 고정자전압 지령치는 다음 식에 의하여 동기회전 좌표계에서 정지좌표 변환부(6)를 통해 정지 좌표계로 변환된다.In integrator (14)

The flux angle given by is orthogonal unit vector

Wow

Used to compute. The stator voltage command value is converted into the stationary coordinate system through the stationary coordinate converting unit 6 in the synchronous rotation coordinate system by the following equation.

(식 24)

(Eq. 24)

Stator voltage command of Fig. 1

The difference between the stator current setpoint and the stator current of the motor is used to calculate the stator voltage setpoint using proportional integrators.

(식 25)

(Eq. 25)

: 적분이득,

: 비례이득이다.here,

: Integral gain,

: Proportional gain.

On the other hand, the stator current command value is converted into the synchronous coordinate system through the synchronous coordinate converter 10 in the stationary coordinate system by the following equation.

(식 26)

(Eq. 26)

The equation for converting two phases to three phases in the two-third-phase conversion unit 7 of FIG.

(식 27)

(Eq. 27)

The equation for converting three phases to two phases in the 3/2 phase conversion unit 9 of FIG.

(식 28)

(Eq. 28)

Equation (16) above is a basic equation for calculating the rotor magnetic flux angle in FIG.

In this equation (17), when calculating the angular speed of the rotor, the slip speed and the speed of the motor are required. When parallel driving is performed by the batch control method, speed differences between the motors may occur due to load imbalance between the motors and slippage.

In this case, since the rotor flux angle calculation is not performed correctly by the method of calculating the speed of the reference motor, vector control may not be performed properly, and thus the entire system may become unstable.

As described above, when induction motor obtains rotor magnetic flux angle through indirect vector control, inaccurate information about the speed of reference motor or variation of its value in several parallel motors, in addition to rotor resistance and stator resistance, can degrade control characteristics. As a result, when vector control is applied to an actual induction motor, the method of estimating rotor resistance, which cannot be measured directly during operation, is being used.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems in the related art, and adopts a parallel vector control method using a method of obtaining the rotor magnetic flux angle without using the rotor resistance value, the stator resistance value, and the motor speed. In case of torque control operation in induction motor vector control operation, it is possible to reduce the cost required to additionally attach the speed sensor to the motor, and to provide a vector control device for a parallel induction motor that can eliminate the effects of a poor speed sensor or precision error. Its purpose is to.

An object of the present invention described above includes a torque and magnetic flux command / current converting unit for converting torque and magnetic flux commands into direct current torque current and magnetic flux current; First and second subtractors for obtaining a difference between the torque and flux current value output from the torque and flux command / current converter and the actual torque and flux current value output from the synchronous coordinate converter; A PID controller which receives the torque and flux current difference signals output from the first and second subtractors and calculates a stator voltage through a proportional integral derivative; A stationary coordinate converter for converting the DC voltage command value of the stator output from the PID controller into an AC voltage command value; A 2/3 phase conversion unit for converting the two-phase AC voltage command value output from the still coordinate conversion unit into three phases; A pulse width modulated inverter for driving several induction motors connected in parallel by pulse width modulating the output voltage of the 2/3 phase converter; A 3/2 phase converter for converting the current output from the inverter into three phases into two phases; A synchronous coordinate converter converting the current output from the 3/2 phase converter into an actual torque and magnetic flux alternating current based on the rotor angular velocity; First and second differentiators for differentiating torque and magnetic flux current output from the torque and magnetic flux command / current converter; On the basis of the torque and the magnetic flux current output from the torque and the magnetic flux command / current converter, the derivative value of the torque and magnetic flux current differentiated through the first and second differentiators, and the DC voltage command value of the stator output from the PID controller. Synchronous angular velocity calculation unit for calculating the synchronous angular velocity through the formula determined by; The integrator can calculate the rotor magnetic flux angle by integrating the synchronous angular velocity of the rotor output from the synchronous angular velocity calculator.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 shows a block diagram of the device of the present invention.

According to the present invention, there is provided a torque and magnetic flux command / current converting section (1) for converting torque and magnetic flux commands into a direct current torque current and a magnetic flux current;

First and second subtractors for obtaining a difference between the torque and the magnetic flux current value output from the torque and the magnetic flux command / current converter 1 and the actual torque and the magnetic flux current value output from the synchronous coordinate converter 10 ( 2) (3);

A PID controller (4) (5) for receiving the torque and flux current difference signals output from the first and second subtractors (2) (3) and calculating the stator voltage through proportional integral derivative;

A stationary coordinate converter (6) for converting a DC voltage command value of the stator output from the PID controller (4) (5) into an AC voltage command value;

A two-third-phase converter (7) for converting the two-phase AC voltage command value output from the stationary coordinate converter (6) into three-phase;

A pulse width modulated inverter (8) for driving a plurality of induction motors (IM1-IMn) connected in parallel by pulse width modulating the output voltage of the two-third-phase converter (7);

A 3/2 phase converter 9 for converting the current output from the inverter 8 into three phases into two phases;

A synchronous coordinate converter (10) for converting the current output from the 3/2 phase converter (9) into an actual torque and magnetic flux alternating current based on the rotor angular velocity;

First and second differentiators (15, 16) for differentiating the torque and the flux component current outputted from the torque and magnetic flux command / current converting section (1);

)를 계산하는 동기각속도 계산부(17)와; The derivative of torque and magnetic flux current output from the torque and magnetic flux command / current converting unit 1 and the torque and magnetic flux current differentiated through the first and second differentiators 15 and 16 and the PID controller ( 4) Synchronous angular velocity (

A synchronous angular velocity calculation unit 17 for calculating);

)를 적 분하여 회전자 자속각(

)을 산출해 내는 적분기(14)로 구성한 것을 특징으로 한다.Synchronous angular velocity of the rotor output from the synchronous angular velocity calculator 17

) By integrating the rotor flux angle (

It is characterized by consisting of an integrator (14) for calculating a).

Referring to the operation and effect of the device of the present invention configured as described above are as follows.

를 추정하는 방법은 다음과 같다.First, the rotor flux angle in the vector control device of the present invention

The method of estimating is as follows.

등가회로에서 고정자측 전압 관계식은Rotary coordinate axis

In the equivalent circuit, the relation of stator voltage is

(식 29)

(Eq. 29)

(식 30)

(Eq. 30)

를 곱하면In equation (29)

Multiply by

(식 31)

(Eq. 31)

를 곱하면In equation (30)

Multiply by

(식 32)

(Eq. 32)

Equation (31) -Equation (32) to remove the term containing the stator side resistance

(식 33)

(Eq. 33)

에 대해 정리하면 식(34)식이 된다.Synchronous angular velocity

If we sum up, it becomes equation (34).

(식 34)

(Eq. 34)

If the non-interference control condition equation (35) is considered in the steady state for converting the stator side magnetic flux into an equation related to the stator current in equation (34), the stator side magnetic flux is summarized as in equations (36) and (37).

(식 35)

(Eq. 35)

(식 36)

(Eq. 36)

(식 37)

(Eq 37)

,

가 급격히 변하지 않는다면 식(39)와 같이 약식 된다.Therefore, by substituting Eq. (36) and (37) into Eq.

,

If is not changed rapidly, it is abbreviated as Eq. (39).

(식 38)

(Eq. 38)

(식 39)

(Eq. 39)

은

로 구할 수 있다. Rotor flux angle

silver

Can be obtained as

As can be seen in equation (38), it can be seen that the stator resistance, rotor resistance and motor speed cannot be seen in the equation itself.

This invention can be implemented in other various forms, without deviating from the mind or main characteristic. Therefore, the above-described embodiments are merely examples in all respects and should not be interpreted limitedly.

The scope of the present invention is shown by the scope of the claims, which are not limited by the specification text, and all modifications and changes belonging to the equivalent scope of the claims are within the scope of the present invention.

According to the present invention as described in detail above, in the case of torque control operation in parallel induction motor vector control operation, the cost required to additionally attach the speed sensor to the motor can be reduced, and the speed sensor is not good because the speed sensor is not installed. The effect of precision errors can be eliminated.

In addition, when indirect vector control is used in the vector control structure, the resistance of the motor rotor is required. This motor constant cannot be directly measured and changes depending on the temperature of the motor, which causes difficulty in vector control. According to the apparatus of the present invention, it is possible to control the parallel induction motors irrespective of the temperature change of the motor by not using the rotor resistance constant, which is a very useful invention.

Claims (2)

A torque and magnetic flux command / current converting unit for converting the torque and magnetic flux command into direct current torque current and magnetic flux current; First and second subtractors for obtaining a difference between the torque and flux current value output from the torque and flux command / current converter and the actual torque and flux current value output from the synchronous coordinate converter; A PID controller which receives the torque and flux current difference signals output from the first and second subtractors and calculates a stator voltage through a proportional integral derivative; A stationary coordinate converter for converting the DC voltage command value of the stator output from the PID controller into an AC voltage command value; A 2/3 phase conversion unit for converting the two-phase AC voltage command value output from the still coordinate conversion unit into three phases; A pulse width modulated inverter for driving several induction motors connected in parallel by pulse width modulating the output voltage of the 2/3 phase converter; A 3/2 phase converter for converting the current output from the inverter into three phases into two phases; A synchronous coordinate converter converting the current output from the 3/2 phase converter into an actual torque and magnetic flux alternating current based on the rotor angular velocity; First and second differentiators for differentiating torque and flux currents output from the torque and flux command / current converters; On the basis of the torque and the magnetic flux current output from the torque and the magnetic flux command / current converter, the derivative value of the torque and magnetic flux current differentiated through the first and second differentiators, and the DC voltage command value of the stator output from the PID controller. Synchronous angular velocity calculation unit for calculating the synchronous angular velocity through the formula determined by; And an integrator for calculating the rotor magnetic flux angle by integrating the synchronous angular velocity of the rotor outputted from the synchronous angular velocity calculator. The method according to claim 1, The equation for obtaining the synchronous angular velocity to be executed in the synchronous angular velocity calculator is

Vector control device of a parallel induction motor, characterized in that.

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