KR100951511B1 - Induction motor controller - Google Patents

Abstract

The present invention relates to an induction motor control device, and compares the rotational speed (W _m ) of the induction motor with the rated speed (W _r _rate) of the induction motor and outputs a first flux current command (i ^* _d _ff), The second magnetic flux by comparing the output voltage (V _out ) value of the current control unit and the voltage maximum (V ^' _max ) value according to the voltage command angle (θ) determined by the static coordinate system voltage command (v ^* _qs , v ^* _ds ). minute current command and outputting a (i ^* _d _fb), a first magnetic flux minute current command (i ^* _d _ff) and the second magnetic flux minute current command (i ^* _d _fb) the magnetic flux minute current command (i ^* _d) by summing By providing a magnetic flux control unit for outputting the present invention, an induction motor control device for making the most of the inverter output voltage characteristics is disclosed.

Induction motor, inverter, torque current, flux current, stop coordinate system, synchronous coordinate system

Description

Induction motor control unit {Apparatus for controlling of induction motor}

The present invention relates to an induction motor control device, and more particularly, to an induction motor control device for smooth field flux control even in a high speed region in which an inverter output voltage is limited.

Inverter (Inverter) is a device used for variable speed drive of the AC motor, typically receives a commercial AC voltage of a fixed size, fixed frequency and converts it into a DC voltage through rectification, and then pulse width modulation (PWM) Using this technique, AC voltage of variable size and variable frequency is needed to drive the motor.

High frequency and high voltage are required to drive an AC motor on the highway. The output frequency of the inverter can be adjusted relatively widely, but the magnitude of the output voltage of the inverter is limited by the magnitude of the commercial AC voltage input to the inverter.

Therefore, in order to drive the high rotational speed of the motor, it is common to perform field weakening control to reduce the magnetic flux current component (d-axis current component) of the motor so that it can be driven even at the current input voltage.

In addition, if it is necessary to operate in a high speed region above the rated speed, it is common to have a flux control device for this purpose.

In the case of the magnetic flux control device of the induction motor, the magnetic flux is reduced by using the portion of the magnetic flux lowered according to the rotational speed for controlling the magnetic flux and the difference between the maximum output voltage of the inverter and the voltage required to drive the current motor. It is usually composed of parts.

1 is a configuration diagram showing an induction motor system driven by a conventional inverter.

As shown in the drawing, the induction motor system is composed of an inverter 101, an induction motor 102, and a speed sensor 103. The inverter 101 has a speed command (W ^* _m ) input from an external device. The induction motor 102 to which the speed sensor 103 is attached is rotated.

The inverter 101 includes a first subtractor 104, a speed control device 105, a second subtractor 106, a torque current control device 107, a flux control device 108, an output voltage calculator 109, and a first subtractor 104. 3 subtractor 110, flux current control device 111, 2-phase / 3-phase converter 112, voltage control device 113, current sensors 114a, 114b, 114c, 3-phase / 2-phase converter 115 , A pulse amplifier 116, a multiplier 117, a slip frequency calculator 118, an adder 119, and an integrator 120.

In the induction motor system configured as described above, when the speed command (W ^* _m ) is input to the inverter 101, the first subtractor 104 has the speed command (W ^* _m ) and the speed sensor 103 and The difference (ie, speed error) of the rotational speed W _m value of the induction motor 102 calculated by the pulse amplifier 116 is calculated and output to the speed control device 105.

The speed control device 105 calculates a torque component current command (i ^* _q ) value for causing the induction motor 102 to rotate according to the speed command (W ^* _m ) value from the speed error.

Second subtractor 106 the speed control device 105 outputs a torque current command (i ^* _q) values and the three-phase / two-phase converter 115 outputs a torque current (i _q) of the value difference of ( That is, torque current difference) is calculated and output to the torque current control device 107.

Torque current control device 107 is a torque-minute voltage command (v ^* _q ) value so that torque current (i _q ) flows by torque current command (i ^* _q ) to induction motor 102 from the torque current error. Calculate

The flux control device 108 receives the rotation speed W _m value of the induction motor and the voltage command V _out value calculated by the output voltage calculator 109, and controls the rotation speed and the motor of the current induction motor 102. Calculate a flux current command (i ^* _d ) value that allows the inverter 101 to maintain the control performance for the induction motor 102 at the magnitude of the output voltage for.

The output voltage calculator 109 calculates the torque divided voltage command (v ^* _q ) value which is the output of the torque current controller 107 and the magnetic flux divided voltage command (v ^* _d ) value which is the output of the magnetic flux current controller 111. Calculate the voltage command (V _out ) value to receive and output.

In this case, the value of the voltage command (V _out ) to be output can be calculated by Equation 1.

The third subtractor 110 is the difference between the magnetic flux current command (i ^* _d ) value received from the magnetic flux control device 108 and the magnetic flux current (i _d ) value that is the output of the three-phase / two-phase converter 115 ( That is, the magnetic flux current error) is calculated and output to the magnetic flux current control device 111.

The flux current control device 111 generates a flux voltage command (v ^* _d ) such that a flux current (i _d ) flows in the induction motor (102) by the flux current command (i ^* _d ) from the flux current error. Calculate the value.

The torque divided voltage command (v ^* _q ) and the flux divided voltage command (v ^* _d ), which are outputs of the torque current control device 107 and the flux current control device 111, are used to control the two-phase / three-phase converter 112. Through the three-phase voltage command (v ^* _a , v ^* _b , v ^* _c ) through the input to the voltage control device 113.

The voltage control device 113 is an inverter 101 through a pulse width modulation (PWM) technique to apply _a voltage of three-phase voltage commands (v ^* _a , v ^* _b , v ^* _c ) to the induction motor 102. To control the output voltage.

The three-phase current i _a , i _b , i _c output to the induction motor 102 is detected through three current sensors 114a, 114b, 114c, and the detected three-phase current i _a , i _b , i _c ) is converted into a torque current i _q and a magnetic flux current i _d through the three-phase / two-phase converter 115.

The vector control technique is applied to increase the torque control performance of the induction motor 102. First, the mechanical rotation speed W _m of the induction motor 102 obtained through the pulse amplifier 116 is added to the multiplier 117. The electric rotational speed W _r of the induction motor 102 is obtained by multiplying the value of (number of poles of the motor / 2).

Next, the rotor magnetic flux angle θ _e is integrated by integrating the electrical rotational speed W _r of the induction motor 102 and the slip frequency W _sl obtained through the slip frequency calculator 118 with the integrator 120. Calculate The rotor flux angle θ _e is the rotor flux position of the induction motor 102.

When the rotor flux angle θ _e is known, the magnetic flux current i _d , which is proportional to the value of the rotor flux, of the three-phase current of the induction motor 102 and the magnetic flux current i _d , is 90 degrees. It can be obtained by decomposing the torque current (i _q ) at an angle and proportional to the output torque of the induction motor 102.

On the other hand, in the induction motor system, the input voltage of the inverter 101 and the rated voltage of the induction motor 102 are used to match each other, the induction motor 102 is generally applied to the rated voltage at the rated frequency.

The magnetic flux control device 108 of the inverter 101 is configured to prevent the counter electromotive force of the induction motor 102 from becoming greater than the output voltage limit of the inverter 101 when the speed of the induction motor 102 becomes higher than the rated speed. In accordance with the increase in the speed of the motor 102 serves to reduce the counter-electromotive force by reducing the magnetic flux current (i _d ) of the motor.

In addition, the magnetic flux control device 108 may change the induction motor 102 even below the rated speed by a parameter change of the induction motor 102 such as a parameter setting error of the inverter 101 and a change in the rotor resistance due to a temperature rise. When the counter electromotive force is higher than the output voltage limit of the inverter 101, serves to reduce the counter electromotive force by reducing the magnetic flux current (i _d ) of the motor.

In such a situation, if the counter electromotive force of the induction motor 102 is not reduced, the torque component voltage command (v ^* _q ) value, which is the output of the torque current controller 107, and the magnetic flux component, which is the output of the magnetic flux current controller 111, are output. The output voltage V _out , which is the combined magnitude of the voltage command v ^* _d , is greater than or equal to the output voltage limit of the inverter 101, and thus the motor control is impossible.

2 is a view showing the configuration of a conventional flux control apparatus.

As shown therein, the flux control device 200 includes a multiplier 201, a discriminator 202, a flux command current generator 203, a memory 204, a subtractor 205, a proportional integral controller 206, a limit. Group 207 and an adder 208.

Referring to FIG. 1, the multiplier 201 receives the mechanical rotational speed W _m of the induction motor 102 calculated by the pulse amplifier 116 and multiplies the constant K (the number of motor poles / 2) to obtain the electrical rotational speed ( W _r ) to get the value.

The discriminator 202 determines whether the electrical rotational speed W _r exceeds the rated speed W _r _ rate of the induction motor 102 and transmits the result to the magnetic flux command current generator 203.

When the magnetic flux instruction current generator 203 exceeds the rated speed (W _r _rate) value of the electrical rotation speed (W _r), the value of the induction motor 102, and outputs the values as shown in equation 2 i ^* _d _ff Shall be.

i ^* _d _ff = (W _r _rate / W _r ) × i _dse _rate

Equation 2 decreases the magnetic flux current command value as the electric rotation speed W _r increases.

The magnetic flux command current generator 203 has a rated magnetic flux current as an output i ^* _d _ff when the electric rotation speed W _r does not exceed the rated speed W _r _rate of the induction motor 102. Print the command i _dse _rate. That is, i ^* _d _ff = i _dse _rate.

The memory 204 stores a maximum voltage value V _max of the phase voltage that the inverter 101 can output. Here, when the line RMS value of the input AC voltage of the inverter 101 is referred to as V _in , the maximum voltage V _max value can be calculated by the equation (3).

The subtractor 205 outputs an output voltage V _out value to be output for the control of the induction motor 102 by the torque current control device 107 and the flux current control device 111, and the inverter 101 outputs. Calculate the difference between the maximum possible voltage (V _max ) values.

Here, as the speed of the induction motor 102 approaches the rated speed, the difference between the output voltage V _out value and the maximum voltage V _max value becomes smaller.

The proportional integration controller 206 generates a control value for causing a difference between the output voltage V _out value and the maximum voltage V _max value to be zero.

The limiter 207 limits the output value of the proportional integration controller 206 to act only in the negative direction.

That is, the limiter 207 lowers the magnetic flux current command i ^* _d of the induction motor 102 when the output voltage V _out becomes larger than the maximum voltage V _max , thereby reducing the output voltage ( Outputs i ^* _d _ fb so that the value of V _out ) becomes smaller than the maximum voltage (V _max ) value.

The adder 208 is induced flux minute current command (i ^* _d _ff) and magnetic flux minute current command (i ^* _d _fb) which is determined by the difference of the output voltage which is determined in inverse proportion to the speed of the electric motor 102 is summed To output the final flux current command (i ^* _d ).

Figure 3 shows the magnitude of the voltage that the inverter can output V _ds -V _qs of the stationary coordinate system It is a graph shown on the coordinates.

Here, the hexagon of 301 represents the maximum value of the voltage that the inverter can output, and it can be seen that the magnitude of the voltage changes according to the phase of the voltage.

의 크기를 가지게 되는데, 위상에 따른 인버터 출력 전압의 크기는 각 꼭지 점에서 최대가 되고, 각 꼭지 점 사이의 정 가운데 위치에서 최소가 된다.The magnitude of the voltage from the origin of the stationary coordinate system to each vertex of the hexagon is obtained when the line RMS value of the input AC voltage is V _in .

The magnitude of the inverter output voltage according to the phase is maximum at each vertex and minimum at the center of the center between the vertices.

Reference numeral 302 denotes the torque divided voltage command (v ^* _q ) and the flux divided voltage command (v ^* _d ) output from the torque current control device and the flux current control device, respectively, V _ds -V _qs on the stationary coordinate system. As shown on the coordinates, the magnitude on the stationary coordinate system has the magnitude of V _out calculated by Equation (1).

Referring to FIG. 2, the conventional flux control apparatus stores the maximum voltage V _max of the inverter calculated by Equation 3 in the memory 204, in which case the maximum value of the inverter output voltage depends on the phase. The problem is that it does not properly reflect changing characteristics.

4 is a view for explaining a problem that occurs when the output voltage maximum value of the inverter in the conventional flux control device is made constant.

Here, the hexagon of 401 denotes the maximum value of the inverter output voltage, and 402 denotes the case where the maximum value of the inverter output voltage is set constant to the value given by Equation 2, and the output voltage vector corresponds to the hexagon. It becomes inscribed form.

This is a case where the inverter uses the maximum voltage that can be used linearly, the current control characteristics are excellent, but the portion shown in 404 is not used, the operation efficiency of the flux control device is reduced.

으로 일정하게 설정한 경우로, 도면 부호 402의 경우보다 출력 전압 벡터를 더 넓은 영역까지 사용할 수 있다.Reference numeral 403 denotes the maximum value of the inverter output voltage.

In this case, the output voltage vector can be used in a wider area than in the case of 402.

However, the output voltage vector is located outside the hexagon as much as the part indicated by reference numeral 405. In this case, the inverter is also outputting a voltage that cannot be actually output, and the calculation of the proportional integral controller is performed, resulting in an accumulation of incorrect voltage error. There is a disadvantage that the performance of the flux control device is degraded.

It is an object of the present invention to provide an induction motor control apparatus which makes the maximum use of inverter output voltage characteristics when controlling a weak magnetic flux in a high speed region in which an inverter output voltage is limited.

According to a preferred embodiment of the induction motor controller of the present invention, _a three-phase sine wave current (i _a , i _b , i _c ) is input to a DC power source input according to a preset voltage command (v ^* _a , v ^* _b , v ^* _c ). ) And a three-phase sine wave current (i _a , i _b , i _c ) output by the induction motor and output to the induction motor as magnetic flux current i _d and torque current i _q . Speed control unit for outputting torque current command (i ^* _q ) by comparing the three-phase / two-phase conversion unit to be converted with the externally input command speed (W ^* _m ) and the rotational speed (W _m ) of the induction motor A magnetic flux control unit for receiving a rotational speed W _m and a static coordinate system voltage command v ^* _qs and v ^* _ds of the induction motor and outputting a magnetic flux current command i ^* _d ; Torque component current command (i ^* _q ) and magnetic flux current command (i ^* _d ) respectively output from the controller and the three-phase / two-phase converter Is a current controller for comparing the torque component current (i _q ) and the magnetic flux component (i _d ) and outputting the torque component voltage command (v ^* _q ) and the flux component voltage command (v ^* _d ), and outputting from the current controller. A coordinate converter converting the synchronous coordinate system voltage command (v ^* _q , v ^* _d ) into a stationary coordinate system voltage command (v ^* _qs , v ^* _ds ) and outputting it to the magnetic flux control unit, and the torque divided voltage output from the current control unit. A two-phase / three-phase converter for converting the command (v ^* _q ) and the magnetic flux divided voltage command (v ^* _d ) into three-phase voltage commands (v ^* _a , v ^* _b , v ^* _c ) and outputting the same to the voltage controller. It is characterized by comprising.

Here, the magnetic flux control unit compares the rotational speed (W _m ) of the induction motor and the rated speed (W _r _rate) of the induction motor to output a first magnetic flux current command (i ^* _d _ff). The maximum voltage V ^' _max according to the voltage command angle θ determined by the current command setting unit, the output voltage V _out of the current control unit, and the static coordinate system voltage commands v ^* _qs and v ^* _ds . ) and the second magnetic flux minutes command current setting section for comparing a value output to the second magnetic flux minute current command (i ^* _d _fb), the first magnetic flux minute current command (i ^* _d _ff) and the second magnetic flux minute current command and an adder for summing (i ^* _d _ fb) and outputting a magnetic flux current command i ^* _d .

The first magnetic flux current command setting unit is a multiplier for multiplying the rotational speed W _m of the induction motor by a constant (K = the number of poles of the induction motor / 2) to obtain an electrical rotational speed W _r , and the electrical rotation. speed at which the output of the first magnetic flux minute current command (i ^* _d _ff) according to the determination whether or not the determined group, wherein the determinator for determining whether the (W _r) is greater than the rated speed of the induction motor (W _r _rate) And a magnetic flux command current generator.

The magnetic flux command current generator is configured to determine the first magnetic flux current command i ^* _d _ff when the electric rotation speed W _r exceeds the rated speed W _r _ rate of the induction motor as a result of the determination of the discriminator. Outputs a value of (W _r _rate / W _r ) × i _dse _rate (rated flux current command).

The flux command current generator is further configured to provide the first flux current command i when the electric rotation speed W _r does not exceed the rated speed W _r _ rate of the induction motor, as a result of the determination of the discriminator. ^It outputs a rated flux current command value (i _dse _rate) as a value _d ^* ff.

The second magnetic flux current command setting unit receives the static coordinate system voltage command (v ^* _qs , v ^* _ds ), and an angle formed by the composite vector (v ^* _ref ) of the static coordinate system voltage command and the D axis in the static coordinate system. An angle calculator for calculating the voltage command angle θ, a sector discriminating unit for discriminating the corresponding sector Sector on the still coordinate system of the composite vector v ^* _ref of the static coordinate system voltage command, and a voltage at the corresponding sector. A voltage maximum calculator for calculating a maximum (V ^′ _max ) value, an output voltage calculator for calculating an output voltage (V _out ) value from the static coordinate system voltage commands (v ^* _qs , v ^* _ds ), and the voltage maximum ( V _^'max) value and the output voltage (V _out) and a subtracter obtaining the difference between the value of the voltage up to ^(V' in proportion to the integration the difference between the _max) value and the output voltage (V _out) value of the second magnetic flux minute current command ( comprises a proportional-integral controller for outputting a ^* i _d _fb) The features.

According to the present invention, by utilizing the inverter output voltage characteristics in the high speed region where the inverter output voltage is limited, the weak magnetic flux control of the induction motor can be efficiently performed.

When the speed of the induction motor is equal to or higher than the rated speed, the counter electromotive force of the induction motor can be effectively reduced by reducing the flux current i _d of the motor in accordance with the speed increase of the induction motor.

Hereinafter, the inverter control apparatus of the present invention will be described in detail with reference to FIGS. 5 to 8.

In describing the present invention, when it is determined that the detailed description of the known technology related to the present invention may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted. The following terms are defined in consideration of the functions of the present invention, and may be changed according to the intention or custom of the user, the operator, and the like. Therefore, the definition should be made based on the contents throughout the specification.

5 is a configuration diagram showing an induction motor system driven by an inverter of the present invention.

As shown in the drawing, the induction motor system is composed of an inverter 501, an induction motor 502, and a speed sensor 503. The inverter 501 has a speed command W ^* _m input from the outside. The induction motor 502 to which the speed sensor 503 is attached is rotated.

The inverter 501 may include a first subtractor 504, a speed controller 505, a second subtractor 506, a torque current controller 507, a flux controller 508, a coordinate converter 509, and a third controller. Subtractor 510, flux current control device 511, two-phase / 3-phase converter 512, voltage control device 513, current sensors 514a, 514b, 514c, three-phase / 2-phase converter 515, Pulse amplifier 516, multiplier 517, sleep frequency calculator 518, adder 519, integrator 520.

In the induction motor system configured as described above, when the speed command (W ^* _m ) is input to the inverter 501, the first subtractor 504 outputs the speed command (W ^* _m ) and the speed sensor 503 and the pulse. The difference (ie, speed error) of the rotation speed W _m value of the induction motor 502 calculated by the amplifier 516 is calculated and output to the speed control device 505.

The speed control device 505 calculates a torque component current command (i ^* _q ) value for causing the induction motor 502 to rotate according to the speed command (W ^* _m ) value from the speed error.

A second subtracter 506, the speed control device 505 outputs a torque current command (i ^* _q) values and the three-phase / two-phase converter 515 outputs the torque current (i _q) of the value difference of ( That is, torque current difference) is calculated and output to the torque current control device 507.

The torque current control device 507 has a torque-minute voltage command v ^* _q value such that the torque-current current i _q flows from the torque current error to the induction motor 502 by the torque current command i ^* _q . Calculate

The flux control device 508 receives the rotational speed (W _m ) of the induction motor from the pulse amplifier 516, and receives the static coordinate system voltage commands v ^* _qs and v ^* _ds from the coordinate converter 509, and the magnetic flux component current. Calculate the command (i ^* _d ) value.

That is, the magnetic flux control device 508 receives the rotation speed W _m value of the induction motor and the static coordinate system voltage commands v ^* _qs , v ^* _ds , and the inverter 501 induces the current rotation speed and the output voltage. The magnetic flux current command (i ^* _d ) value is calculated so as to maintain the maximum control performance for the motor 502.

The coordinate converter 509 receives the torque divided voltage command (v ^* _q ) value and the flux divided voltage command (v ^* _d ) value, which are synchronous coordinate system voltage commands, from the torque current controller 507 and the flux current controller 511. It receives the input and converts it into the voltage commands v ^* _qs and v ^* _ds in the stationary coordinate system.

Here, the coordinate converter 509 converts the synchronous coordinate system voltage commands v ^* _q and v ^* _d into the static coordinate system voltage commands v ^* _qs and v ^* _ds by Equations 4 and 5 below.

In Equations 3 and 4, θ _e represents the rotor flux angle.

A third subtracter 510 flux minute current command (i ^* _d) of the value and the three-phase / two-phase converter 515, the output of the magnetic flux minute current (i _d) of the value difference received from the flux control unit 508 ( That is, the magnetic flux current error) is calculated and output to the magnetic flux current control device 511.

The magnetic flux current control device 511 calculates a magnetic flux divided voltage command v ^* _d from the magnetic flux current error.

The torque divided voltage command (v ^* _q ) and the flux divided voltage command (v ^* _d ), which are outputs of the torque current control device 507 and the magnetic flux current control device 511, are used for the two-phase / three-phase converter 512. Through the three-phase voltage command (v ^* _a , v ^* _b , v ^* _c ) through the input to the voltage control device 513.

The voltage control device 513 is an inverter 501 through a pulse width modulation (PWM) technique to apply _a voltage of three phase voltage commands (v ^* _a , v ^* _b , v ^* _c ) to the induction motor 502. To control the output voltage.

The three phase currents i _a , i _b , i _c output to the induction motor 502 are detected through three current sensors 514a, 514b, 514c, and the detected three phase currents i _a , i _b , i _c ) is converted into a torque current i _q and a magnetic flux current i _d through the three-phase / two-phase converter 515.

6 is a view showing the configuration of a magnetic flux control device of the inverter of the present invention.

As shown therein, the multiplier 601, the discriminator 602, the magnetic flux command current generator 603, the angle calculator 604, the sector discriminator 605, the voltage maximum calculator 606, the output voltage calculator ( 607, a subtractor 608, a proportional integration controller 609, a limiter 610, and an adder 611.

Referring to FIG. 5, the multiplier 601 receives the mechanical rotational speed W _m of the induction motor 502 calculated by the pulse amplifier 516 and multiplies the constant K (the number of motor poles / 2) to obtain the electrical rotational speed ( W _r ) to get the value.

The decider 602 transmits the result to the magnetic flux instruction current generator 603 to determine if the electrical rotation speed (W _r) value exceeds the rated speed of the induction motor (502) (W _r _rate) value.

The magnetic flux instruction current generator 603, if it exceeds the electrical rotation speed (W _r), the value of the rated speed of the induction motor (502) (W _r _rate) value, the electrical rotation speed (W _r), the greater the value of flux min. Outputs i ^* _d _ ff value so that the current command value becomes smaller. Where i ^* _d _ff = (W _r _rate / W _r ) × i _dse _rate.

When the electric rotation speed W _r does not exceed the rated speed W _r _rate of the induction motor 502, the magnetic flux command current generator 603 outputs a rated magnetic flux current command as an output i ^* _d _ff. Output i _dse _rate. That is, i ^* _d _ff = i _dse _rate.

The angle calculator 604 calculates the angle θ from the static coordinate system voltage commands v ^* _qs and v ^* _ds values input from the coordinate converter 509.

Here, with reference to FIG. 7, the angle θ will be described. With the D-axis voltage command as the X-axis and the Q-axis voltage command as the Y-axis, the v ^* _ds value is placed on the X axis and the v ^* _qs value is Y. When placed on the axis, the angle formed by the composite vector v ^* _ref of the D-axis voltage command and the Q-axis voltage command and the D-axis is θ.

The angle θ can be obtained by equation (6).

The sector discriminator 605 determines which sector the position of the composite vector v ^* _ref is in and outputs a sector value Sector # from the voltage command angle θ calculated by the angle calculator 604.

7 shows the position of each sector. Since the voltage limiting hexagon consists of a total of six positive triangles, each positive triangle forms one sector, and the sector value is determined by the angle θ.

That is, 0 ° <θ ≤ 60 ° → Sector I, 60 ° <θ ≤ 120 ° → Sector II, 120 ° <θ ≤ 180 ° → Sector III, 180 ° <θ ≤ 240 ° → Sector IV, 240 ° <θ ≦ 300 ° → Sector Ｖ, 300 ° <θ ≦ 360 ° → Sector VI.

The voltage maximum calculator 606 calculates a voltage maximum V ^′ _max value from the voltage command angle θ and the sector value Sector #.

The maximum amount of voltage that can be output at the voltage command angle θ calculated from the angle calculator 604 is the points on the hexagonal sides shown in bold dotted lines, as shown in FIG. 8, and this value is equal to the voltage command angle θ. Given differently.

The voltage maximum (V ^' _max ) value can be obtained by Equation 7.

(V_in은 인버터 입력 전압의 선간 RMS값)이고, m은 섹터 값(Sector #)을 나타낸다. here,

(V _in is the line RMS value of the inverter input voltage), and m is the sector value (Sector #).

For example, by substituting m = 1, the maximum voltage (V ^' _max ) obtained from Sector I can be obtained, which can be obtained by Equation (8).

Referring to Equation 8, the maximum voltage (V ^' _max ) value in Sector I is the case of θ = π / 6, the maximum is the case of θ = 0 and θ = π / 3 Able to know.

Here, by substituting θ = π / 6 to obtain the magnitude when the voltage maximum (V ^' _max ) is the minimum, it can be seen that it is the same as the value obtained from Equation 3. It can be seen that the flux is controlled to the minimum size.

On the other hand, the voltage maximum (V ^' _max ) value can also be obtained by the equation (7), after determining the sector position of the composite vector v ^* _ref , using the equation (9) voltage command angle between 0 ° and 60 ° after translation, and it may obtain a maximum voltage (V _^'max) value using the equation (10).

The output voltage calculator 607 obtains an output voltage V _out to be output by the torque current controller 507 and the flux current controller 511 through Equation (9).

The subtractor 608 may output an output voltage V _out value for controlling the motor calculated by the output voltage calculator 607 and a maximum voltage V output by the current inverter calculated by the voltage maximum calculator 606. ^' _max ) Calculate the difference between the values.

The proportional integration controller 609 generates a control value for causing a difference between the output voltage V _out value and the voltage maximum V ^' _max value to be zero.

The limiter 610 operates the output value of the proportional integral controller 609 only in the minus direction to induce when the output voltage V _out and the voltage maximum V ^' _max are greater than the output value. outputs a i ^* _d _fb to such that the magnetic flux minute current command (i ^* _d) lowering the output voltage (V _out), the value of the electric motor 502 is smaller than the maximum voltage value (V ^_'max).

By adding the adder 611 is induced flux minute current command (i ^* _d _ff) and magnetic flux minute current command (i ^* _d _fb) which is determined by the difference of the output voltage which is determined by the speed of the electric motor 502 Outputs the final flux current command (i ^* _d ).

Although the present invention has been described in detail with reference to exemplary embodiments above, those skilled in the art may make various modifications within the scope of the present invention without departing from the scope of the present invention. Will understand.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined by the claims below and equivalents thereof.

1 is a configuration diagram showing an induction motor system driven by a conventional inverter.

2 is a view showing the configuration of a conventional flux control apparatus.

Figure 3 shows the magnitude of the voltage that the inverter can output V _ds -V _qs of the stationary coordinate system Graph plotted on coordinates.

4 is a view for explaining a problem that occurs when the output voltage maximum value of the inverter in the conventional flux control device is constant.

5 is a configuration diagram showing an induction motor system driven by an inverter of the present invention.

6 is a diagram illustrating a configuration of a magnetic flux control device of an inverter of the present invention.

Fig. 7 is a graph showing a composite vector (v ^* _ref ), a voltage command angle (θ) and an angular sector (Sector) on a still coordinate system of the present invention.

8 is a graph showing a maximum voltage (V _^'max) values that are given in accordance with the voltage command angle (θ) of the present invention.

Explanation of symbols on the main parts of the drawings

501: Inverter 502: Induction Motor

503: speed sensor 504: first subtractor

505: speed control device 506: second subtractor

507: torque current control device 508: flux control device

509: coordinate converter 510: third subtractor

511: flux current control device 512: two-phase / three-phase converter

513: voltage control device 514a, 514b, 514c: current sensor

515: three-phase / two-phase converter 516: pulse amplifier

517: multiplier 518: slip frequency calculator

519: adder 520: integrator

601: multiplier 602: discriminator

603: flux command current generator 604: angle calculator

605: sector discriminator 606: voltage maximum value calculator

607: output voltage calculator 608: subtractor

609: proportional integral controller 610: limiter

611: Adder

Claims (10)

A voltage controller configured to convert a DC power input according to a preset voltage command (v ^* _a , v ^* _b , v ^* _c ) into a three-phase sine wave current (i _a , i _b , i _c ) and output it to an induction motor; A three-phase / two-phase converter for converting the three-phase sine wave currents i _a , i _b , i _c output by the voltage controller into magnetic flux currents i _d and torque currents i _q ; Reference speed inputted from outside (W ^* _m) and the rotation speed (W _m) to a speed control unit for outputting a torque current command (i ^* _q) comparison of the induction motor; A magnetic flux controller configured to receive a rotational speed W _m and a static coordinate system voltage command (v ^* _qs , v ^* _ds ) of the induction motor and output a flux current command (i ^* _d ); Torque component current command (i ^* _q ) and magnetic flux current command (i ^* _d ) output from the speed control unit and magnetic flux control unit, respectively, torque component current (i _q ) and magnetic flux output from the three-phase / two-phase conversion unit. A current controller which compares the minute current i _d and outputs a torque minute voltage command v ^* _q and a magnetic flux minute voltage command v ^* _d ; And And a coordinate converter configured to convert a synchronous coordinate system voltage command (v ^* _q , v ^* _d ) output from the current controller into a stop coordinate system voltage command (v ^* _qs , v ^* _ds ) and output the same to the magnetic flux control unit. The magnetic flux control unit, A first flux current command setting unit configured to output a first flux current command i ^* _d _ff by comparing the rotational speed W _m of the induction motor with a rated speed W _r _rate of the induction motor; Comparing the output voltage (V _out ) value of the current controller and the voltage maximum (V ^' _max ) value according to the voltage command angle (θ) determined by the static coordinate system voltage commands (v ^* _qs , v ^* _ds ) A second flux current command setting unit for outputting two flux current commands i ^* _d _ fb; And an adder configured to sum the first magnetic flux current command (i ^* _d _ff) and the second magnetic flux current command (i ^* _d _fb) to output a magnetic flux current command (i ^* _d ). Device. The method of claim 1, And a rotor flux angle calculator configured to calculate a rotor flux angle θ _e from the rotational speed W _m of the induction motor and output the rotor flux angle to a three-phase and two-phase converter. delete The method of claim 1, The first magnetic flux current command setting unit, A multiplier for multiplying the rotational speed (W _m ) of the induction motor by a constant (K = number of poles / 2 of the induction motor) to obtain an electrical rotational speed (W _r ); A discriminator for determining whether the electrical rotational speed W _r exceeds a rated speed W _r _ rate of an induction motor; And And a magnetic flux command current generator for outputting the first magnetic flux current command (i ^* _d _ff) according to whether the discriminator is judged. The method of claim 4, wherein The magnetic flux command current generator, As a result of the determination of the discriminator, when the electric rotation speed W _r exceeds the rated speed W _r _rate of the induction motor, the value of the first magnetic flux current command i ^* _d _ff is determined as (W _r _rate). / W _r ) × i _dse _rate value. Here, i _dse _rate represents a rated magnetic flux current command value. The method of claim 4, wherein The magnetic flux command current generator, As a result of the determination of the discriminator, when the electrical rotational speed W _r does not exceed the rated speed W _r _rate of the induction motor, the rated magnetic flux fraction is set to the value of the first magnetic flux current command i ^* _d _ff. Induction motor control device characterized in that for outputting a current command (i _dse _rate) value. The method of claim 1, The second magnetic flux current command setting unit, The voltage command angle (θ), which is an angle formed by the composite vector (v ^* _ref ) of the stationary coordinate system voltage command and the D axis in the stationary coordinate system, is input to the stationary coordinate system voltage command (v ^* _qs , v ^* _ds ). Angle calculator; A sector discriminating unit for discriminating a corresponding sector on the still coordinate system of the composite vector v ^* _ref of the still coordinate system voltage command; Voltage maximum value computing unit for computing a maximum voltage (V _^'max) value in the relevant sector; An output voltage calculator for calculating an output voltage V _out value from the static coordinate system voltage command v ^* _qs , v ^* _ds ; A subtractor for obtaining a difference between the voltage maximum (V ^′ _max ) and the output voltage (V _out ); And Induction comprising the proportional-integral controller for proportionally integrating the difference between the voltage up to (V _^'max) value and the output voltage (V _out) value output to the second magnetic flux minute current command (i ^* _d _fb) Motor controller. The method of claim 7, wherein The sector discriminator determines the sector, 0 ° <θ ≤ 60 ° to Sector I, 60 ° <θ ≤ 120 ° to Sector II, 120 ° <θ ≤ 180 ° to Sector III, 180 ° <θ ≤ 240 ° to Sector IV, 240 ° An induction motor control device characterized in that Sector 이면 when <θ ≤ 300 °, and Sector VI when 300 ° <θ ≤ 360 °. The method of claim 7, wherein The voltage maximum (V ^' _max ) value is calculated by Equation 1 below. Equation  One

here,

(V _in is the line RMS value of the inverter input voltage), and m is the sector value. The method of claim 7, wherein The maximum voltage (V ^' _max ) value is calculated by the following equation (2) and (3) induction motor control apparatus. Equation  2

Equation  3

here,

(V _in is the line RMS value of the inverter input voltage), and m is the sector value.

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