JP2021018749A - Frequency response analysis method - Google Patents

Abstract

To provide a frequency response analysis method of a pilot governor for a reverse operation type pressure governor capable of appropriately inputting an actual pressure sine wave or the like as input and measuring a driving pressure as an output response thereof, and also capable of performing a frequency response analysis that analyzes control characteristics from these values.SOLUTION: A frequency response analysis method performs: a pressure vibration imparting step of imparting cycle pressure vibration to a first chamber H1; a pressure vibration measuring step of measuring a simulated secondary pressure involving the cycle pressure vibration to be introduced to the first chamber H1; a vibration measuring step of measuring a driving pressure to be introduced to a driving pressure introducing path L4 from a third chamber H3 in a state where the cycle pressure vibration is imparted in the pressure vibration imparting step; and a frequency response analysis step of carrying out a frequency response analysis on the basis of an amplitude and a phase of the simulated secondary vibration to be measured in the pressure vibration measuring step, and an amplitude and a phase of vibration in another section to be measured in the vibration measuring step.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for analyzing the frequency response of a pilot governor used as a counter-actuated pressure regulator.

Conventionally, as a pressure regulating device that can control the displacement of the main valve body of the main governor when the secondary pressure rises or falls below the set pressure, a reverse operation type pressure regulating device and a pilot governor used for the reverse pressure regulating device are known. (See Patent Document 1).
On the other hand, as one method for analyzing a control system, frequency response analysis for examining control characteristics from a response to an input such as a sine wave is known. The frequency response analysis is often used in electrical and mechatronic systems, but it can of course be applied to pressure regulators such as pilot governors, which are feedback control devices that do not require electricity. For example, in the pilot type governor, the input signal is used as the secondary pressure for inputting the input signal to the pilot, and the output signal is used as the secondary pressure for the piping on the downstream side of the main valve. The stability of the system can be determined by performing frequency response analysis for inputs at various frequencies as pressure.

Japanese Unexamined Patent Publication No. 2017-182718

As described above, when the frequency response analysis of the pilot governor or the pilot governor is performed, it is necessary to apply a sine wave or the like, which is a periodic vibration, to the secondary pressure detection chamber as an input signal. However, in the pilot governor or the pilot governor used in the generally known reverse-acting pressure regulating device as shown in Patent Document 1, the driving pressure discharged from the driving pressure chamber flows into the secondary pressure detection chamber. Therefore, an accurate sine wave cannot be given as an input signal. For example, by reducing the pipeline resistance of the secondary pressure introduction path that is communicated with the secondary pressure detection chamber, the drive pressure discharge resistance from the secondary pressure introduction path can be reduced. However, in this method, a method in which the secondary pressure detection chamber is airtightly configured and its volume is forcibly changed to give a sine wave as pressure cannot be applied.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to be able to appropriately input an actual pressure sine wave or the like as an input and to measure the driving pressure as an output response thereof, and control from those values. It is an object of the present invention to provide a frequency response analysis method for a pilot governor of a counter-actuated pressure regulator capable of performing frequency response analysis for analyzing characteristics.

The frequency response analysis method for achieving the above objectives is
It is a frequency response analysis method of the pilot governor used as a reverse operation type pressure regulator, and its characteristic configuration is
The first chamber, which is partitioned by the housing and the first diaphragm and the secondary pressure introduction path is communicated with each other, and the opening hole which is partitioned by the housing, the first diaphragm, and the second diaphragm and opened to the outside. The second chamber formed in the housing is partitioned by the housing, the second diaphragm, and the third diaphragm, and the primary pressure introduction path is communicated and connected, and the drive pressure is introduced into the drive pressure chamber of the main governor. A third chamber in which the drive pressure introduction path is communicated with each other, and a first urging member that urges the third diaphragm toward the third chamber.
A connecting member that connects the first diaphragm, the second diaphragm, and the third diaphragm so as to have the same displacement amount in the displacement direction.
In the displacement direction, the secondary pressure introduction end is urged by the second urging member from the side of the second diaphragm toward the primary pressure introduction end, which is the introduction end of the primary pressure introduction path, to open and close the primary pressure introduction end. An exhaust valve that adjusts the inflow amount of the primary pressure side fluid introduced into the third chamber from the primary side pressure introduction end, and
The pilot having an open valve which is connected to the exhaust valve and opens and closes an opening formed in the second diaphragm to adjust the amount of exhaust gas released from the side of the third chamber to the side of the second chamber. It is a frequency response analysis method executed using a governor.
A pressure vibration applying step of applying periodic pressure vibration to the first chamber, and
A pressure vibration measurement step for measuring a simulated secondary pressure accompanied by the periodic pressure vibration introduced into the first chamber,
A vibration measurement step of measuring vibration at another part generated by receiving the periodic pressure vibration while the periodic pressure vibration is applied in the pressure vibration applying step.
Frequency to perform frequency response analysis based on the amplitude and phase of simulated secondary pressure vibration measured in the pressure vibration measurement step and the amplitude and phase of vibration in the other part measured in the vibration measurement step. The point is to execute the response analysis process.

A pilot governor having three diaphragms having the above-mentioned characteristic configuration has a different configuration from a pilot governor having two diaphragms which has been generally used as a reverse-acting pressure regulator, but both of them have two. When the secondary pressure rises, all the diaphragms fall and the drive pressure is discharged (in the case of a three-diaphragm configuration, it is discharged to the outside via the second chamber, and in the case of a two-diaphragm configuration, the secondary pressure is discharged. When it is discharged to the detection chamber) and the secondary pressure drops, the drive pressure is supplied to the main governor. Therefore, it basically exhibits the same frequency response characteristics as a pilot governor with two diaphragms. it is conceivable that.
Further, according to the pilot governor having the above-mentioned characteristic configuration, the exhaust pressure released from the third chamber through the release valve is guided to the second chamber and not to the first chamber. Therefore, in the first chamber, A secondary pressure can be introduced as periodic pressure vibration as an input that is not disturbed by the discharge pressure.
Therefore, by using a pilot governor having the above-mentioned characteristic configuration, frequency response analysis is performed based on the periodic pressure vibration applied in the pressure vibration applying process and the driving pressure measured in the vibration measuring process. It is possible to obtain characteristics substantially equivalent to the frequency response characteristics of the pilot governor of a commonly used reverse-acting pressure regulator.
Therefore, the frequency response of the pilot governor of the counter-actuated pressure regulator that can appropriately input an actual pressure sine wave or the like as an input and can perform frequency response analysis that analyzes the control characteristics from those values using the output as a driving pressure. The analysis method can be realized.

The pilot governor having the above-mentioned characteristic configuration can be used for verification for knowing the frequency response characteristics of the conventional pilot governor as described above, and can be put into practical use as a pilot governor for a reverse-acting pressure regulator. You can also.

Further features of the frequency response analysis method
The pressure vibration applying step is a step of applying the periodic pressure vibration to the first chamber at a plurality of different frequencies.
The pressure vibration measurement step is a step of measuring the simulated secondary pressure generated at a plurality of different frequencies.
The vibration measurement step is a step of measuring the driving pressure generated for each of the periodic pressure vibrations generated at a plurality of different frequencies.
The frequency response analysis step is
Gain derived from the ratio of the amplitude of the simulated secondary pressure vibration measured in the pressure vibration measurement step at each of a plurality of different frequencies to the amplitude of the vibration in the other part measured in the vibration measurement step. And the gain output process that outputs for each of multiple frequencies
The difference between the phase of the simulated secondary pressure vibration measured in the pressure vibration measurement process at each of a plurality of different frequencies and the phase of vibration at the other part measured in the vibration measurement process is set for each of a plurality of frequencies. Phase output process to output to
It has a stability determination step of determining the stability of the pilot governor based on a board diagram created from the gain output output in the gain output step and the phase output output in the phase output step. At the point.

According to the determination, since the determination is based on the actual measurement, the determination can be made more realistically than the method based on the numerical analysis premised on various assumptions.

It is a schematic block diagram of the pilot governor used for frequency response analysis. It is an operation diagram when the pilot governor used for frequency response analysis operates. It is a graph diagram of the simulated secondary pressure accompanied by the periodic pressure vibration as an input to the pilot governor, and the graph diagram of the drive pressure as an output.

The frequency response analysis method of the pilot governor 100 according to the embodiment of the present invention can appropriately input an actual pressure sine wave or the like as an input, measure the driving pressure as the output response, and analyze the control characteristics from those values. Regarding what to do.

As shown in FIG. 1, the reverse-acting pressure regulating device 200 includes a reverse-acting main governor 10 that adjusts the secondary pressure of the fluid flow path L0 to a set pressure, and a pilot that introduces a driving pressure into the main governor 10. It is configured to include a governor 100.

The main governor 10 is provided with a main diaphragm D0 provided along the diaphragm plate 14, and the internal space thereof is divided into a fifth chamber H5 and a sixth chamber H6 by the main diaphragm D0. The main governor 10 is provided with a main valve body V0 that opens and closes the main opening K0 provided in the fluid flow path L0, and the main valve body V0 is connected to the main diaphragm D0 by a connecting rod 16 and is connected to the main diaphragm D0. It is configured to open and close in a form that moves in conjunction with. Further, in the fifth chamber H5, a main urging spring G0 that urges the main diaphragm D0 toward the valve closing direction side of the main valve body V0 is arranged.

The pilot governor 100 is composed of a first chamber H1 which is partitioned by a housing K and a first diaphragm D1 and a secondary pressure introduction path L2 is communicated with each other, and a housing K, a first diaphragm D1 and a second diaphragm D2. The second chamber H2 in which the opening hole K1 is partitioned and opened to the outside is formed in the housing K, and the housing K, the second diaphragm D2, and the third diaphragm D3 are partitioned, and the primary pressure introduction path L1 is communicated with each other. The third chamber H3 and the third diaphragm D3 are connected to the third chamber H3 in which the drive pressure introduction path L4 for introducing the drive pressure into the sixth chamber H6 (an example of the drive pressure chamber) of the main governor 10 is communicated with each other. A connection in which the first urging member G1 urging to the side, the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3 are connected so as to have the same displacement amount in the displacement direction (arrow Z direction in FIG. 1). The member R and the primary pressure introduction end L1a are urged by the second urging member G2 from the side of the second diaphragm D2 in the displacement direction toward the primary pressure introduction end L1a which is the introduction end of the primary pressure introduction path L1. Is connected to the exhaust valve V1 that opens and closes to adjust the inflow amount of the primary pressure side fluid introduced into the third chamber H3 from the primary pressure introduction end L1a, and is formed in the second diaphragm D2. It has an open valve V2 that opens and closes the opening DP2a to adjust the amount of discharge that is released from the side of the third chamber H3 to the side of the second chamber H2.
Here, the drive pressure introduction path L4 is communicated with the secondary side pressure introduction path L2 via a third fluid flow path L3 having a throttle 39 for narrowing the flow path diameter. Further, the base end side end portion of the first urging member G1 opposite to the third diaphragm D3 is attached to a saucer G2a provided in a form of being screwed into a female screw portion G2b provided on the inner peripheral surface of the housing K. The saucer G2a is in contact with each other, and is configured to be movable in the displacement direction (arrow Z direction in FIG. 1) by rotating while being screwed into the female screw portion G2b.

The first diaphragm D1 is provided with the first diaphragm plate DP1, the second diaphragm D2 is provided with the second diaphragm plate DP2, and the third diaphragm D3 is provided with the third diaphragm plate DP3. The member R is provided in a form of connecting the first diaphragm plate DP1, the second diaphragm plate DP2, and the third diaphragm plate DP3.

When the secondary pressure P2 of the fluid flow path L0 is higher than the set pressure by appropriately setting the urging force of the first urging member G1 and the second urging member G2 in the above configuration, FIG. 2A ), The pressure of the first chamber H1 is increased, so that the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3 are first opposed to the urging force of the first urging member G1. It is displaced toward the urging member G1. As a result, the exhaust valve V1 is operated to the closed side and the open valve V2 is operated to the open side, the introduction of the primary pressure P1 to the third chamber H3 is stopped, and the pressure of the third chamber H3 is reduced to the second chamber H3. It is discharged to the outside through the chamber H2 and the opening hole K1. As a result, the pressure in the sixth chamber H6 is discharged to the outside through the drive pressure introduction path L4, the opening DP2a, and the opening hole K1, the pressure in the sixth chamber H6 decreases, and the fifth chamber H5 and the sixth chamber H6 The main diaphragm D0 is displaced toward the sixth chamber H6 due to the pressure difference from the chamber H6. Therefore, the main valve body V0 of the main governor 10 is operated to the closed side, the secondary pressure P2 of the fluid flow path L0 is lowered, and the secondary pressure P2 is adjusted to the set pressure.
The opening degree of the opening DP2a is configured to increase as the pressure difference between the secondary pressure P2 and the set pressure increases.

On the other hand, when the secondary pressure P2 of the fluid flow path L0 is lower than the set pressure, as shown in FIG. 2B, the secondary side pressure introduction path L2 communicates with the secondary side of the fluid flow path L0. The pressure in the first chamber H1 of the pilot governor 100 is reduced, and the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3 are displaced toward the first chamber H1 by the urging force of the first urging member G1. To do. As a result, the exhaust valve V1 operates to the open side and the open valve V2 operates to the closed side, and the primary pressure of the fluid flow path L0 is introduced into the third chamber H3 via the primary side pressure introduction path L1. The pressure in the chamber H3 rises. Then, the pressure of the third chamber H3 whose pressure has increased is introduced as a drive pressure into the sixth chamber H6 of the main governor 10 via the drive pressure introduction path L4, the pressure of the sixth chamber H6 also increases, and the pressure of the sixth chamber H6 also rises, and the fifth chamber H5 The main diaphragm D0 is displaced toward the fifth chamber H5 due to the pressure difference between the and the sixth chamber H6. Therefore, the main valve body V0 of the main governor 10 is operated to the open side, the secondary pressure P2 of the fluid flow path L0 is increased, and the secondary pressure P2 is adjusted to the set pressure.

The pilot governor 100 having the three diaphragms described so far has patent document 1 (Patent Document 1) when a simulated secondary pressure P2 accompanied by periodic pressure vibration is applied to the first chamber H1 as the secondary pressure detection chamber. Japanese Patent Application Laid-Open No. 2017-12718) has the following configuration so as to obtain frequency response characteristics substantially equivalent to those of a pilot governor having two diaphragms used in a conventional reverse-acting pressure regulator. There is.

The effective pressure receiving areas of the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3 are configured to be substantially the same, and preferably, the effective pressure receiving area is the effective pressure receiving pressure of the diaphragm of the conventional reverse-acting pilot governor. It is configured equal to the area.
Further, the connecting member R connecting the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3 extends along the displacement direction (arrow Z direction in FIG. 1) and the first diaphragm plate DP1 and the second diaphragm. It can be composed of a plurality of rod-shaped members R1 (two in the embodiment) connecting the plate DP2 and the third diaphragm plate DP3.

Further, the relationship between the stroke of the secondary pressure P2 and the exhaust valve V1 and the mass of the vibrable portion can be substantially the same as that of the conventional pilot governor. Incidentally, the vibrable portion includes the connecting member R, the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3. More precisely, the above relationship is also influenced by the masses of the exhaust valve V1, the open valve V2, the first diaphragm D1, the second diaphragm D2, and the third diaphragm D3.

Further, in order to introduce a simulated secondary pressure accompanied by periodic pressure vibration as an input to the first chamber H1 as the secondary pressure measurement chamber, the secondary side pressure introduction path L2 has a secondary pressure introduction path L2. An on-off valve 51 for switching the opening and closing of the is provided.
Further, a pressure vibration generator 50 (an example of a pressure vibration applying unit) for applying periodic pressure vibration to the first chamber H1 is provided for the first chamber H1, and the pressure vibration generator 50 is provided. It is composed of a pressure introduction valve V3 that controls pressure introduction to the first chamber H1 and a pressure discharge valve V4 that controls pressure discharge from the first chamber H1. To add an explanation, the pressure introduction valve V3 is provided in a form of opening and closing the primary side pressure introduction path L1 which is communicated with the first chamber H1, and the pressure discharge valve V4 is communicated with the first chamber H1. It is provided in a form of opening and closing the open air flow path L5.
With the on-off valve 51 closed, the control device C alternately switches between opening and closing the pressure introduction valve V3 and the pressure discharge valve V4 based on the detected pressure value of the first pressure sensor S1 to control the pressure. Vibration can be generated.

Further, a first pressure sensor S1 capable of measuring a simulated secondary pressure accompanied by periodic pressure vibration introduced into the first chamber H1 is provided on the side of the first chamber H1 with respect to the on-off valve 51. Further, a second pressure sensor S2 capable of measuring the drive pressure is provided in the drive pressure introduction path L4, and the control device C can receive the pressure measured by the first pressure sensor S1 and the second pressure sensor S2. It is configured in.
The control device C includes the amplitude and phase of the simulated secondary pressure vibration accompanied by the periodic pressure vibration introduced into the first chamber H1 measured by the first pressure sensor S1, and the amplitude and phase measured by the second pressure sensor S2. A frequency response analysis is performed based on the amplitude and phase of the vibration at the site (eg, the vibration of the drive pressure).

Now, an example of the frequency response analysis method of the pilot governor 100 described so far will be described.

The operator closes the on-off valve 51 in order to isolate the first chamber H1 and the secondary side of the fluid flow path L0 so as to prohibit the propagation of pressure.
Next, the control device C sets the frequency of the periodic pressure vibration generated in the pressure vibration generator 50 to an initial value (for example, a minimum value of a plurality of frequencies is set: 0.1 Hz as an example). The pressure vibration generator 50 executes a pressure vibration applying step of generating periodic pressure vibration of a set frequency.
After that, the control device C executes a pressure vibration measurement step of receiving the pressure as a simulated secondary pressure accompanying the periodic pressure vibration measured by the first pressure sensor S1 at the set frequency, and the second pressure sensor. The vibration measurement step of receiving the drive pressure vibration (an example of the pressure vibration at another part generated by receiving the periodic pressure vibration) measured by S2 is executed.
The simulated secondary pressure as an input and the driving pressure as an output to be measured at a predetermined set frequency are, for example, values as shown in FIG. Incidentally, the frequency set in FIG. 3 is 0.5 Hz. In FIG. 3, the measured values are displayed in plots, and the sine approximation is shown in curves.

The control device C gradually increases the frequency of the periodic pressure vibration generated by the pressure vibration generator 50. Here, it is preferable that the frequency is exponentially increased until the frequency of the set periodic pressure vibration reaches a predetermined upper limit value.
Next, the control device C outputs a board diagram from the amplitude and phase of the simulated secondary pressure vibration accompanying the periodic pressure vibration measured for each frequency and the amplitude and phase of the vibration at other parts to respond to the frequency. Perform the frequency response analysis step to perform the analysis.
Specifically, the amplitude A1 of the simulated secondary pressure vibration accompanied by the periodic pressure vibration measured in the pressure vibration measurement process for each of a plurality of different measured frequencies and the vibration in other parts measured in the vibration measurement process. Simulated secondary pressure vibration with periodic pressure vibration measured in the gain output process that outputs the gain G derived from the ratio of the amplitude A2 to the amplitude A2 for each of a plurality of frequencies and the pressure vibration measurement process for each of a plurality of different frequencies. The phase output process that outputs the difference between the phase of the above and the phase of the vibration at other parts measured in the vibration measurement process for each of a plurality of frequencies is executed, and the gain and phase output process output in the gain output process. The phase difference output in is plotted on the board diagram.

The control device C determines the stability of the pilot governor 100 based on the Bode diagram created from the gain margin derived from the gain output in the gain output process and the phase margin derived from the phase output process. The stability determination step (an example of the frequency response analysis process) for determination is executed.

[Another Embodiment]
(1) The first pressure sensor S1 may directly measure the pressure in the first chamber H1 as the secondary pressure detection chamber.
Further, the drive pressure measured by the second pressure sensor S2 may be the secondary pressure of the downstream piping of the main valve body V0.

(2) As another example of the configuration of the pressure generator 50, for example, a form in which the internal pressure of the first chamber H1 is vibrated by a roots pump, or a chamber in which a chamber chamber communicating with the first chamber H1 is heated and cooled is heated and cooled. It is also possible to adopt a configuration in which pressure vibration is formed by expansion and contraction of the gas inside.

It should be noted that the configuration disclosed in the above embodiment (including another embodiment, the same shall apply hereinafter) can be applied in combination with the configuration disclosed in other embodiments as long as there is no contradiction. The embodiments disclosed in the present specification are examples, and the embodiments of the present invention are not limited thereto, and can be appropriately modified without departing from the object of the present invention.

The frequency response analysis method of the pilot governor of the present invention can appropriately input an actual pressure sine wave or the like as an input, measure the driving pressure as an output response, and analyze the control characteristics from those values. It can be effectively used as a frequency response analysis method for the pilot governor of a viable reverse-acting pressure regulator.

10: Main governor 14: Diaphragm plate 100: Pilot governor 200: Reverse operation type pressure regulator D1: 1st diaphragm D2: 2nd diaphragm D3: 3rd diaphragm G1: 1st urging member G2: 2nd urging member H1 : 1st chamber H2: 2nd chamber H3: 3rd chamber K: Housing K1: Open hole L0: Fluid flow path L1: Primary pressure introduction path L1a: Primary pressure introduction end L2: Secondary pressure introduction path L4: Drive pressure introduction path P1: Primary pressure P2: Secondary pressure R: Connecting member V0: Main valve body V1: Exhaust valve V2: Open valve

Claims (2)

This is a frequency response analysis method for pilot governors used as a reverse-acting pressure regulator.
The first chamber, which is partitioned by the housing and the first diaphragm and the secondary pressure introduction path is communicated with each other, and the opening hole which is partitioned by the housing, the first diaphragm, and the second diaphragm and opened to the outside. The second chamber formed in the housing is partitioned by the housing, the second diaphragm, and the third diaphragm, and the primary pressure introduction path is communicated and connected, and the drive pressure is introduced into the drive pressure chamber of the main governor. A third chamber in which the drive pressure introduction path is communicated with each other, and a first urging member that urges the third diaphragm toward the third chamber.
A connecting member that connects the first diaphragm, the second diaphragm, and the third diaphragm so as to have the same displacement amount in the displacement direction.
In the displacement direction, the secondary pressure introduction end is urged by the second urging member from the side of the second diaphragm toward the primary pressure introduction end, which is the introduction end of the primary pressure introduction path, to open and close the primary pressure introduction end. An exhaust valve that adjusts the inflow amount of the primary pressure side fluid introduced into the third chamber from the primary side pressure introduction end, and
The pilot having an open valve which is connected to the exhaust valve and opens and closes an opening formed in the second diaphragm to adjust the amount of exhaust gas released from the side of the third chamber to the side of the second chamber. It is a frequency response analysis method executed using a governor.
A pressure vibration applying step of applying periodic pressure vibration to the first chamber, and
A pressure vibration measurement step for measuring a simulated secondary pressure accompanied by the periodic pressure vibration introduced into the first chamber,
A vibration measurement step of measuring vibration at another part generated by receiving the periodic pressure vibration while the periodic pressure vibration is applied in the pressure vibration applying step.
Frequency to perform frequency response analysis based on the amplitude and phase of simulated secondary pressure vibration measured in the pressure vibration measurement step and the amplitude and phase of vibration in the other part measured in the vibration measurement step. A frequency response analysis method that executes a response analysis step. The pressure vibration applying step is a step of applying the periodic pressure vibration to the first chamber at a plurality of different frequencies.
The pressure vibration measurement step is a step of measuring the simulated secondary pressure generated at a plurality of different frequencies.
The vibration measurement step is a step of measuring the driving pressure generated for each of the periodic pressure vibrations generated at a plurality of different frequencies.
The frequency response analysis step is
Gain derived from the ratio of the amplitude of the simulated secondary pressure vibration measured in the pressure vibration measurement step at each of a plurality of different frequencies to the amplitude of the vibration in the other part measured in the vibration measurement step. And the gain output process that outputs for each of multiple frequencies
The difference between the phase of the simulated secondary pressure vibration measured in the pressure vibration measurement process at each of a plurality of different frequencies and the phase of vibration at the other part measured in the vibration measurement process is set for each of a plurality of frequencies. Phase output process to output to
It has a stability determination step of determining the stability of the pilot governor based on a board diagram created from the gain output output in the gain output step and the phase output output in the phase output step. The frequency response analysis method according to claim 1.

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