KR102739237B1 - Induction Motor using Torque Observer and Method for Controlling Thereof - Google Patents

Abstract

An induction motor using a torque observer capable of improving speed reduction due to load variation and a control method thereof are disclosed. This comprises configuring a torque observer using voltage, current, and speed information and induction motor parameters, and compensating for the observed torque with different gains for each voltage magnitude and frequency, thereby obtaining a desired speed output. In addition, speed information required for the torque observer in a transient state is input as a constant value, and a moving average filter, an offset, and a weight are used to reduce torque measurement errors due to parameter changes, thereby preventing feedforward overcompensation.

Description

Induction motor using torque observer and method for controlling thereof {Induction Motor using Torque Observer and Method for Controlling Thereof}

The present invention relates to an induction motor, and more specifically, to an induction motor using a torque observer capable of improving speed reduction due to load variation and a control method thereof.

Induction motors have the advantages of simple structure and low price compared to other motors, and are used in various fields such as large water pumps, water supply equipment, and pumps. In addition, because they operate stably, they are also used in large-capacity water supply and industrial pumps of 100 kW or more.

One of the methods for simply driving such induction motors is the scalar control (V/f control) method. The scalar control method has a disadvantage in that it cannot obtain the desired speed output because it is an open-loop control that does not use feedback and cannot apply changes in input due to external load fluctuations. Therefore, a method that can improve the speed reduction according to the load by compensating for the error between the output speed of the induction motor and the command speed through a PI controller together with the scalar control is being used. However, this method has the problem that it shows a lower output speed than the command speed, and in particular, it has a large output speed reduction when the load fluctuates.

Korean Patent Registration No. 10-0976670

The technical problem to be achieved by the present invention is to provide an induction motor using a torque observer and a control method thereof capable of improving speed reduction due to load variation by feed-forward compensating the torque observed using the torque observer to the voltage magnitude and frequency.

The induction motor using the torque observer of the present invention to solve the above problem has a stator current ( ), stator voltage (V _s ) and the observed stator flux ( based on the speed information (ω _r ) of the actual induction motor. ) to observe torque ( ) and the observed torque ( observed by the torque observer) ) the compensation voltage (V _com ) and the command frequency ( ) Three-phase command voltage with feed-forward compensation ( ) includes a scalar controller that outputs a

The above torque observer measures the stator voltage (V _s ), the speed information of the induction motor (ω _r ) and the error of the stator current ( ) using the stator flux ( ) for outputting the magnetic flux observation unit; and the stator magnetic flux ( ) and the stator current ( ) using the above observation torque ( ) may include a torque calculation unit that calculates the torque.

The above flux observation unit is expressed by the following equation using the A matrix, B matrix, and G matrix.

According to,

Here,

,

,

,

,

, and

At this time, L _S can represent the stator inductance, L _r can represent the rotor inductance, M can represent the mutual inductance, R _S can represent the stator resistance, R _r can represent the rotor resistance, and ω can represent the speed of the induction motor.

The above G matrix is the error of the stator current ( ) and the actual motor speed (ω _r ) information are input and fed back, and can be differentiated from the above B matrix.

The above torque calculation unit is as follows:

According to,

Here,

is the observed torque observed by the torque observer, P is the number of poles of the induction motor,

is the d-axis observation flux, is the q-axis sensing current, is the q-axis observation flux, can represent the d-axis sensing current.

The above torque observer outputs the observed torque (from the torque calculation unit) ) is input, and the above observation torque ( ) may further include a torque control unit that reduces the error from the actual torque by applying a moving average filter (MV filter), offset, and weight.

The above scalar controller is configured to control the command frequency ( ) is input, and the input command frequency ( ) by applying gain to the command voltage ( ) outputting a gain input section, the command voltage ( outputted from the gain input section) ) for applying a boost voltage to the command voltage ( ) and a first adder for adding the boost voltage, and the command voltage ( outputted from the first adder ) multiplied by a proportional constant (K _V ) to the observed torque ( ) and the compensation voltage (V _com ) to output the maximum command voltage value (V _m ), and the second adder outputs the command frequency ( ) and the proportional constant (K _f ) multiplied by the above observed torque ( ) input and a waveform forming unit that outputs a three-phase sine wave, and multiplies the maximum value of the command voltage (V _m ) and the three-phase sine wave to obtain the three-phase command voltage ( ) may include a multiplier that outputs a .

The three-phase sine wave output from the waveform forming unit may have a maximum waveform value of 1.

The above compensation voltage (V _com ) is the input speed error ( ) can be the output voltage of the PI controller.

The control method of an induction motor using a torque observer of the present invention to solve the above problem is to measure the stator current ( ), stator voltage (V _s ) and the observed stator flux ( based on the speed information (ω _r ) of the actual induction motor. ) to observe torque ( ) and the torque observation step for outputting the observed torque ( ) is input to the scalar controller, and the input observed torque is converted to a compensation voltage (V _com ) and a command frequency ( ) Three-phase command voltage with feed-forward compensation ( ) includes a scalar control step that outputs the result.

The above torque observation step is the error of the stator voltage (V _s ), the speed information of the induction motor (ω _r ) and the stator current ( ) using the stator flux ( ) and a stator flux generation step for outputting the stator flux ( ) and the stator current ( ) is used to calculate the observed torque in the torque calculation unit ( ) may include a torque calculation step for calculating the torque.

The above flux observation unit is expressed by the following equation using the A matrix, B matrix, and G matrix.

According to,

Here,

,

,

,

,

, and

At this time, L _S can represent the stator inductance, L _r can represent the rotor inductance, M can represent the mutual inductance, R _S can represent the stator resistance, R _r can represent the rotor resistance, and ω can represent the speed of the induction motor.

The above torque calculation unit is as follows:

According to,

Here,

is the observed torque observed by the torque observer, P is the number of poles of the induction motor,

is the d-axis observation flux, is the q-axis sensing current, is the q-axis observation flux, can represent the d-axis sensing current.

The above scalar control step is, the command frequency ( ) by applying gain to the command voltage ( ) and outputs the output command voltage ( ) and outputting the boost voltage, the command voltage ( to which the boost voltage is added) ) multiplied by a proportional constant (K _V ) to the observed torque ( ) and the step of adding the compensation voltage (V _com ) to output the maximum command voltage value (V _m ), and the observed torque ( multiplied by the proportional constant (K _f ) ) and the above command frequency ( ) and a step of outputting a three-phase sine wave by using the maximum value of the command voltage (V _m ) and the three-phase sine wave to obtain the three-phase command voltage ( ) may include a step of outputting the result.

According to the present invention, a torque observer is configured using voltage, current, and speed information and induction motor parameters, and a desired speed output can be obtained by compensating the observed torque with different gains for each voltage size and frequency.

In addition, feedforward overcompensation can be prevented by inputting the speed information required for the torque observer in a transient state as a constant value and reducing the torque measurement error due to parameter changes by using a moving average filter, offset, and weights.

The technical effects of the present invention are not limited to those mentioned above, and other technical effects not mentioned will be clearly understood by those skilled in the art from the description below.

Fig. 1 is a block diagram showing an induction motor using the torque observer of the present invention.
FIG. 2 is a block diagram showing an embodiment of a torque observer according to the present invention.
FIG. 3 is a block diagram showing another embodiment of a torque observer according to the present invention.
Figure 4 is a block diagram showing a scalar controller according to the present invention.
Figure 5 is a graph comparing the speed difference between an induction motor to which the feedforward of the present invention is applied and an induction motor to which the feedforward is not applied.
Figure 6 is a graph comparing the observed torque and the actual torque of an induction motor to which the torque observer of the present invention is applied.
Figure 7 is a graph showing the change in command voltage of an induction motor to which the feedforward compensation of the present invention is applied and an induction motor to which the feedforward compensation is not applied.

The present invention can be modified in various ways and has various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, this is not intended to limit the present invention to specific embodiments, and it should be understood that it includes all modifications, equivalents, and substitutes included in the spirit and technical scope of the present invention. In describing the present invention, if it is determined that a specific description of a related known technology may obscure the gist of the present invention, the detailed description thereof will be omitted.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the attached drawings. When describing with reference to the attached drawings, identical or corresponding components are assigned the same drawing numbers and redundant descriptions thereof are omitted.

Example

Fig. 1 is a block diagram showing an induction motor using the torque observer of the present invention.

Referring to FIG. 1, an induction motor applying a torque observer according to the present invention includes a torque observer (100), a scalar controller (200), and a SVPWM inverter (300).

The torque observer (100) measures the stator current ( ), stator voltage (V _s ) and speed (ω _r ) of the actual induction motor, the observed stator flux ( ) to observe torque ( ) can be output. At this time, the torque observer (100) can output the error ( ) can increase the accuracy of the magnetic flux estimated through the feedback gain by the G matrix (113).

The scalar controller (200) is configured to control the command frequency ( ), compensation voltage (V _com ) and observed torque ( observed from the torque observer (100) ) is input, and the three-phase command voltage ( ) can be output to the SVPWM (Space Vector Pulse Width Modulation) inverter (300). At this time, the compensation voltage (V _com ) input to the scalar controller (200) is the input speed error ( ) may be the output voltage of the PI controller (400).

The three-phase command voltage output from the scalar controller (200) ) is input to the SVPWM inverter (300), and the SVPWM inverter (300) receives the three-phase command voltage ( ) is calculated by the SVPWM algorithm, and the three-phase voltage ( ) can be output and input to an induction motor (IM). At this time, the SVPWM inverter (300) applies the output voltage to the stator of the motor so that the command voltage can be maintained on average, and senses the stator voltage (V _s ), stator current ( ) and the actual induction motor speed (ω _r ) are input to the torque observer (100) to obtain the observed torque ( ) is created.

FIG. 2 is a block diagram showing an embodiment of a torque observer according to the present invention.

Referring to FIG. 2, a torque observer (100) according to the present invention may include a magnetic flux observation unit (110) and a torque calculation unit (120).

The magnetic flux observation unit (110) measures the stator current ( ), stator voltage (V _s ) and the actual speed (ω _r ) of the induction motor are input, and the stator flux observed based on the input information ( ) can be printed.

Here, the stator flux ( ) can be expressed as in mathematical expression 1.

That is, the magnetic flux observation unit (110) A matrix (111) formed by B matrix (112) formed by It can include a G matrix (113) formed by Equation 1. In addition, the stator current ( ) and the observed stator flux ( ) may include an integrator (114) for deriving the equation.

As in mathematical expression 1, the magnetic flux observation unit (110) of the present invention observes the stator current ( ) and observed magnetic flux ( ) In the B matrix (112), the stator voltage ( ) In the G matrix (113), the difference between the observed stator current and the actual stator current ( ) can be multiplied into each matrix as input.

Here, A ₁₁ , A ₁₂ , A ₂₁ and A ₂₂ , which are matrix A (111), can be expressed as mathematical expression 2, respectively.

Here, L _S is the stator inductance, , ω _r is the actual speed of the induction motor, R _r is the rotor resistance, L _r is the rotor inductance, , , , and M represent mutual inductance.

In addition, B ₁ and B ₂ , which are B matrices (112), can be expressed as in mathematical expression 3 below, and G ₁ and G ₂ , which are G matrices (113), can be expressed as in mathematical expression 4, respectively.

Here, K is can be expressed as

By examining the operation of the magnetic flux observation unit (110) according to the present invention using Fig. 2 and the mathematical formulas above, the difference value between the observed stator current and the actual stator current ( ) and the G matrix (113) into which the actual induction motor speed (ω _r ) is input is fed back to the stator voltage ( ) is inputted into the B matrix (112) and is differentiated. In addition, the G matrix (113) differentiated from the B matrix (112) is the observed stator current ( ), observed stator flux ( ) and the speed (ω _r ) of the actual induction motor are added to the input A matrix (111) and input to the integrator (114), and the stator current ( ) observed by the integrator (114) is ) and observed stator flux ( ) is output. At this time, the observed stator flux ( ) is the stator current ( ) is input to the torque calculation unit (120), and the observed stator current ( ) is the stator current ( ) and is then re-input into the G matrix (113).

The torque calculation unit (120) calculates the observed stator flux (output from the flux observation unit (110)) ) and stator current ( ) is input and the observed torque ( is calculated through calculation) ) is printed.

The observed torque (calculated in the torque calculation unit (120)) ) can be expressed as mathematical formula 5 below.

Here, is the observed torque observed in the torque calculation unit (120), P is the number of poles of the induction motor, is the observed flux along the d-axis, is the sensing current of the q-axis, is the observed flux along the q-axis, represents the sensing current of the d-axis, respectively.

That is, the torque observer (100) according to the present invention measures the difference between the stator current observed by the magnetic flux observer (110) and the actual stator current ( ) is fed back into the G matrix (113), and the speed (ω _r ) of the actual induction motor is fed back into the G matrix (113) and the A matrix (111), and the stator flux ( ) is fed back into the A matrix (111), the B matrix (112), and the G matrix (113). ) is observed. The stator flux ( observed in the manner described above) is ) is used to obtain the observed torque through the torque calculation unit (120). ) by outputting the observed torque ( ) can be operated to follow the actual torque value.

FIG. 3 is a block diagram showing another embodiment of a torque observer according to the present invention.

Referring to FIG. 3, another embodiment of a torque observer (100) according to the present invention may include a magnetic flux observation unit (110), a torque calculation unit (120), and an observation torque control unit (130).

Here, the magnetic flux observation unit (110) and the torque calculation unit (120) may be the same as the magnetic flux observation unit (110) and the torque calculation unit (120) illustrated in Fig. 2. However, in another embodiment of the torque observer (100), the observed torque ( ) is input to the observation torque control unit (130), and the input observation torque ( ) can be controlled and output from the observation torque control unit (130).

For example, the observation torque control unit (130) may include a moving average filter, an offset, and a weight. That is, the observation torque ( ) can be output with moving average filters, offsets, and weights applied.

For example, observation torque ( ) and the actual torque may cause a large torque observation error due to parameter fluctuations caused by transient conditions or heat, which may result in overcompensation. Accordingly, the torque observer (100) according to the present invention inputs a constant value of the speed information required for the torque observer (100) in a transient state, and the observed torque () observed by the magnetic flux observation unit (110) and the torque calculation unit (120) ) can reduce torque measurement errors caused by parameter changes by reducing vibration through a moving average filter, increasing the average by applying an offset, and reducing the amplitude by applying weights, thereby preventing feedforward overcompensation.

In addition, the torque observer (100) has a problem that an error may occur during actual measurement if the sampling time is not considered. Therefore, the present invention uses Zero Order Hold (ZOH) to ensure that the voltage, current, and speed information input to the torque observer (100) to consider the sampling time have the same sampling time before being input to the torque observer (100). In addition, in a transient state, a constant speed is input to reduce the measurement error caused by the fluctuating parameters of the stator and rotor, but when the steady state is reached, the speed of the actual induction motor is input to measure the torque, thereby reducing the error between the actual torque and the observed torque.

Figure 4 is a block diagram showing a scalar controller according to the present invention.

Referring to FIG. 4, the scalar controller (200) according to the present invention has a command frequency ( ), compensation voltage (V _com ) and observed torque ( observed from the torque observer (100) ) is input, a, b, c 3-phase command voltage ( ) can be printed.

Additionally, the scalar controller (200) may include a gain input unit (210), a boost voltage input unit (220), a waveform forming unit (230), and a multiplier (240).

The gain input section (210) has a command frequency ( ) is entered, and the entered command frequency ( ) is multiplied by a constant gain to obtain the command voltage for scalar control. ) so that the maximum waveform value (V _m ) is output. That is, the gain input unit (210) outputs the command frequency ( ) increases, so that the voltage also increases steadily, the command frequency ( ) to input the gain to the command voltage ( ) is printed.

The command voltage output from the gain input section (210) ) can be output by adding the boost voltage input from the boost voltage input section (220). For example, the command frequency ( ) is low, the operating performance of the induction motor (IM) may deteriorate due to voltage drop in a transient state. Therefore, the command voltage ( output from the gain input unit (210) ) By applying the boost voltage input from the boost voltage input section (220), it is possible to prevent the deterioration of the operating performance of the induction motor due to voltage drop.

Reference voltage with added boost voltage ( ) is the compensation voltage (V _com ) and the observed torque ( ) can be added to output the maximum command voltage value (V _m ). In addition, the output maximum command voltage value (V _m ) can be input to the multiplier (240). Here, the compensation voltage (V _com ) is input to the speed error ( ) may be the output of the PI controller (400) according to the observed torque ( ) is the observation torque ( ) can be the observed torque multiplied by the proportional constant (K _V ). That is, the maximum value of the three-phase sine wave can be determined by the proportional constant (K _V ).

Also, observation torque( ) is multiplied by a proportional constant (K _f ) to obtain the command frequency ( ) can be input to the waveform forming unit (230). That is, the waveform forming unit (230) can input the command frequency ( ) and the observed observed torque ( ) is input, but the observed torque ( ) is multiplied by a proportional constant (K _f ) to prevent the motor speed from decreasing as the torque increases. ) can be entered.

Therefore, the waveform forming unit (230) is configured to generate a command frequency ( ) is the observed torque ( ) multiplied by the proportional constant (K _f ). ) and perform an integration operation on the added value so that the a, b, and c three-phase sine (sin) waves can be output. At this time, the three-phase sine wave output from the waveform forming unit (230) may be a three-phase sine wave with a maximum waveform value of 1.

In the multiplier (240), the maximum command voltage value (V _m ) and the three-phase sine wave output from the waveform forming unit (230) are input, and the maximum command voltage value (V _m ) and the three-phase sine wave are multiplied to obtain the three-phase command voltage ( ) can be output. That is, the three-phase command voltage ( output from the multiplier (240) according to the command voltage maximum value (V _m ) ) can be determined in size.

As described above, the scalar controller (200) according to the present invention has a command frequency ( ) to generate a three-phase sine wave with a size of 1, and a command frequency ( ) and the three-phase command voltage ( ) to perform scalar control. That is, speed control is performed by compensating the compensation voltage (V _com ) to the voltage size, and the observed torque ( ) can be controlled robustly against external load fluctuations by multiplying the proportional constants (K _V , K _f ) to compensate for the voltage magnitude and the frequency of the command wave, respectively.

Figure 5 is a graph comparing the speed difference between an induction motor to which the feedforward of the present invention is applied and an induction motor to which the feedforward is not applied.

Here, Fig. 5(a) shows the speed difference between the actual speed of the induction motor and the command speed to which the feedforward is not applied, and Fig. 5(b) shows the speed difference between the actual speed and the command speed of the induction motor to which the feedforward compensation according to the torque observer (100) of the present invention is applied. At this time, the induction motor applied a PI controller for speed error, and the motor reached a steady state of 1800 rpm for 0 to 3 seconds and was operated, and a rated load of about 200 N m was applied for 3 seconds during the steady state operation of the motor.

Regarding the difference between the command speed and the actual speed during the operation of the induction motor, the induction motor before the feedforward is applied has a difference of 20.32 rpm between the command speed and the actual speed when the steady state is reached after the rated load is applied, as shown in Fig. 5(a), whereas the induction motor of the present invention with the feedforward compensation applied has a difference of 9.95 rpm when the steady state is reached, as shown in Fig. 5(b). That is, it can be confirmed that the induction motor of the present invention with the feedforward compensation applied is improved by 51% compared to the induction motor when the feedforward compensation is not applied, and it can also be confirmed that the time to reach the steady state is faster.

Figure 6 is a graph comparing the observed torque and the actual torque of an induction motor to which the torque observer of the present invention is applied.

Here, Fig. 6(a) shows the difference between the actual torque and the observed torque of an induction motor to which the torque observer (100) of the present invention is applied but feedforward compensation is not applied, and Fig. 6(b) shows the difference between the actual torque and the observed torque of an induction motor to which the torque observer (100) of the present invention is applied and feedforward compensation is applied.

Referring to FIGS. 6(a) and (b), it can be confirmed that the actual torque and the observed torque are observed similarly in both FIGS. 6(a) and (b) to which the torque observer (100) of the present invention is applied regardless of the feedforward compensation, and in particular, it can be confirmed that the observed torque is observed very similarly to the actual torque in both FIGS. 6(a) and (b) in the steady state.

Figure 7 is a graph showing the change in command voltage of an induction motor to which the feedforward compensation of the present invention is applied and an induction motor to which the feedforward compensation is not applied.

Here, Fig. 7(a) shows the reference voltage and A-phase reference voltage of an induction motor to which feedforward is not applied, and Fig. 7(b) shows the reference voltage and A-phase reference voltage of an induction motor to which feedforward compensation of the present invention is applied.

Referring to Fig. 7(a), it can be seen that there is a large difference between the actual speed of the motor and the command speed because even if the rated torque is applied for 3 seconds at the maximum command voltage value, the maximum command voltage value does not change, and therefore, there is no change when checking the A-phase command voltage.

In addition, referring to Fig. 7(b), when feedforward compensation is applied as in the present invention, when the rated torque is applied for 3 seconds at the maximum value of the command voltage, it can be confirmed that the maximum value of the command voltage is changed after 3 seconds, and thus the A-phase command voltage is also changed. That is, it can be confirmed that when feedforward compensation is applied, the compensation result affects the maximum value of the command voltage.

As described above, the induction motor using the torque observer of the present invention can obtain a desired speed output by configuring a torque observer (100) using voltage, current, and speed information and induction motor parameters, and compensating for the observed torque with different gains for each voltage size and frequency. In addition, by inputting speed information required for the torque observer (100) in a transient state as a constant value, and reducing torque measurement errors due to parameter changes using a moving average filter, an offset, and a weight, feedforward overcompensation can be prevented.

Meanwhile, the embodiments of the present invention disclosed in this specification and drawings are merely specific examples presented to help understanding, and are not intended to limit the scope of the present invention. It will be apparent to those skilled in the art to which the present invention pertains that other modified examples based on the technical idea of the present invention can be implemented in addition to the embodiments disclosed herein.

100: Torque Observation Unit 110: Magnetic Flux Observation Unit
120: Torque calculation unit 130: Observation torque control unit
200: Scalar controller 210: Gain input section
220: Boost voltage input section 230: Waveform forming section
240: Multiplier 300: SVPWM Inverter
400 : PI controller

Claims (14)

Stator current( ), stator voltage (V _s ) and speed (ω _r ) of the actual induction motor, the observed stator flux ( ) to observe torque ( ) torque observer outputting; and
The observed torque observed by the above torque observer ( ) the compensation voltage (V _com ) and the command frequency ( ) Three-phase command voltage with feed-forward compensation ( ) includes a scalar controller that outputs
The above torque observer,
The above stator voltage (V _s ), the actual induction motor speed (ω _r ) information and the stator current error ( ) using the stator flux ( ) for outputting the flux observation unit; and
The above stator flux ( ) and the stator current ( ) using the above observation torque ( ) An induction motor using a torque observer including a torque calculation unit that calculates a torque. delete In the first paragraph,
The above flux observation unit is expressed by the following equation using the A matrix, B matrix, and G matrix.
According to,
Here,
,
,
,
,
, and
At this time, an induction motor using a torque observer where L _S is the stator inductance, L _r is the rotor inductance, M is the mutual inductance, R _S is the stator resistance, R _r is the rotor resistance, and ω _r represents the actual speed of the induction motor. In the third paragraph,
The above G matrix is the error of the stator current ( ) and an induction motor using a torque observer that receives information on the speed (ω _r ) of the actual induction motor and feeds it back, and then differentiates it from the B matrix. In the first paragraph,
The above torque calculation unit is as follows:
According to,
Here,
is the observed torque observed by the torque observer, P is the number of poles of the induction motor,
is the d-axis observation flux, is the q-axis sensing current, is the q-axis observation flux, An induction motor using a torque observer that represents the d-axis sensing current. In the first paragraph,
The above torque observer outputs the observed torque (from the torque calculation unit) ) is input, and the above observation torque ( ) An induction motor using a torque observer further including a torque control unit that reduces the error from the actual torque by applying a moving average filter (MV filter), offset, and weight. In the first paragraph, the scalar controller,
The above command frequency ( ) is input, and the input command frequency ( ) by applying gain to the command voltage ( ) gain input section that outputs;
The command voltage output from the above gain input section ( ) A boost voltage input section for applying a boost voltage;
The above command voltage ( ) and a first adder for adding the boost voltage;
The command voltage output from the first adder ( ) multiplied by a proportional constant (K _V ) to the observed torque ( ) and a second adder that adds the compensation voltage (V _com ) and outputs the maximum command voltage value (V _m );
The above command frequency ( ) and the proportional constant (K _f ) multiplied by the above observed torque ( ) and a waveform forming unit that outputs a three-phase sine wave; and
Multiply the above command voltage maximum value (V _m ) and the above three-phase sine wave to obtain the three-phase command voltage ( ) Induction motor using a torque observer including a multiplier outputting a torque. In Article 7,
An induction motor using a torque observer in which the three-phase sine wave output from the waveform forming section has a maximum waveform value of 1. In Article 7,
The above compensation voltage (V _com ) is the input speed error ( ) An induction motor using a torque observer which is the output voltage of a PI controller. In the torque observer, the stator current ( ), stator voltage (V _s ) and speed (ω _r ) of the actual induction motor, the observed stator flux ( ) to observe torque ( ) torque observation step; and
The observed torque observed by the above torque observer ( ) is input to the scalar controller, and the input observed torque is converted to a compensation voltage (V _com ) and a command frequency ( ) Three-phase command voltage with feed-forward compensation ( ) includes a scalar control step that outputs
The above torque observation step is,
In the magnetic flux observation section, the stator voltage (V _s ), the actual induction motor speed (ω _r ) information, and the stator current error ( ) using the stator flux ( ) to generate a stator flux; and
The above stator flux ( ) and the stator current ( ) is used to calculate the observed torque in the torque calculation unit ( ) A control method for an induction motor using a torque observer including a torque calculation step for calculating a torque. delete In Article 10,
The above flux observation unit is expressed by the following equation using the A matrix, B matrix, and G matrix.
According to,
Here,
,
,
,
,
, and
At this time, L _S is the stator inductance, L _r is the rotor inductance, M is the mutual inductance, R _S is the stator resistance, R _r is the rotor resistance, and ω _r is the control method of the induction motor using a torque observer representing the actual speed of the induction motor. In Article 10,
The above torque calculation unit is as follows:
According to,
Here,
is the observed torque observed by the torque observer, P is the number of poles of the induction motor,
is the d-axis observation flux, is the q-axis sensing current, is the q-axis observation flux, A control method for an induction motor using a torque observer that represents a d-axis sensing current. In the 10th paragraph, the scalar control step,
The above command frequency ( ) by applying gain to the command voltage ( ) and outputs the output command voltage ( ) and outputting the boost voltage;
The above boost voltage is added to the command voltage ( ) multiplied by a proportional constant (K _V ) to the observed torque ( ) and a step of adding the compensation voltage (V _com ) to output the maximum command voltage value (V _m );
The above observed torque ( multiplied by the proportional constant (K _f ) ) and the above command frequency ( ) to output a three-phase sine wave; and
Multiply the above command voltage maximum value (V _m ) and the above three-phase sine wave to obtain the three-phase command voltage ( ) A method for controlling an induction motor using a torque observer including a step of outputting a torque.