JP4824285B2 - Impedance automatic matching method - Google Patents

Description

This invention relates to the automatic impedance matching how to insert between the high-frequency signal transmission line and the load.

  In order to efficiently propagate a high-frequency signal without reflection on the transmission line, it is necessary to match the characteristic impedance of the transmission line with the impedance of the load. The impedance matching device is provided to automatically match the impedance between the transmission line and the load to minimize loss, and has a function to automatically adjust its own impedance according to the power transmission state. is doing.

  Examples of the load include a transmission antenna that receives power from a transmission line, a plasma chamber, and a receiver, and a high-frequency power source that sends power to the transmission line and a reception antenna. In general, the matching circuit that realizes impedance matching differs depending on the impedance of the load. When the real part of the load impedance is smaller than the characteristic impedance of the transmission line, a so-called inverted L-type matching circuit shown in FIG. 1 is used. When the real part of the load impedance is larger than the characteristic impedance of the transmission line, a so-called L-shaped matching circuit shown in FIG. 2 is used.

Japanese Patent Application Laid-Open No. 2003-046359 (Patent Document 1) shows an example of an inverted L-type impedance matching device, which includes a first variable reactance for adjusting amplitude and a second variable for adjusting phase. A matching device that has reactances and matches load impedances by controlling the reactances according to the detection values of the amplitude detection and phase detection units is shown.
Japanese Patent Laying-Open No. 2003-046359 (paragraph number 0014, FIG. 1)

  In a conventional automatic control type matching device, a detection circuit provided between a transmission line and a matching circuit detects a deviation in amplitude and phase with respect to an impedance target value, and operates two variable reactances separately. Thus, it is a common practice to converge the detected amplitude and phase deviation values to zero.

  However, for example, in the above impedance matching device, the detected values of the amplitude and phase differ depending on the transmitted power, and the detection sensitivity differs if the impedance on the output side differs. Further, the first variable reactance for adjusting the amplitude and the second variable reactance for adjusting the phase are individually controlled. For this reason, since the two detected values of phase and amplitude are both affected by fluctuations in both the first and second variable reactances, the two detected values cannot be controlled independently and interfere with each other. There is also. Therefore, the gain adjustment for determining the convergence speed cannot be handled quantitatively, and the adjustment must be performed according to the situation in the field.

  Further, since the two movable parts interfere with each other, they may come and go before and after the convergence to the convergence point and may diverge. Furthermore, for example, when the purpose is to suppress the reflected power of the propagating power, the reflected power may become larger before it converges to the convergence point.

Therefore, an object of the present invention is to quantitatively handle the gain adjustment for determining the convergence speed, and it is easy to optimize the convergence speed of the tuning of the high-frequency signal transmission line and the load or the impedance adjustment. it is to provide an automatic impedance matching how.

The present invention includes a transmission line, matching between the load is inserted, a automatic impedance matching method for matching the impedance of the transmission line and the load side, integer if circuit, between the transmission line and the load And a shunt reactance element shunt connected between the input side or output side of the series reactance element and the ground potential line, and at least the power from the transmission line of the matching circuit It includes a sensor unit that detects either impedance or admittance at the power output unit to the input unit or transmission line, and an error function that represents the difference between the target value for matching impedance and the detected value of the sensor unit is detected value. The automatic impedance matching method is defined by a vector represented by the real part and imaginary part based on
(A) detecting a detection value of the sensor unit;
(B) A series reactance element and a shunt reactance element for exponentially attenuating an error function to converge an error with respect to a target value of the real part and imaginary part of impedance or admittance based on a detection value of the sensor unit Rate of change
dX / dt = A− ¹ · K · e,
However,
X is a reactance X ₁ of the series reactance element, column vector of the reactance X ₂ of the shunt reactance element,
K is a diagonal matrix whose components are negative
A represents a time change of the error function determined by the matching circuit, the relationship between the time variation of the reactance X ₂ of the reactance X ₁ and shunt reactance element of the series reactance elements, in de / dt = A · dX / dt Matrix defined,
e is a column vector consisting of real and imaginary parts of the error function,
A step of varying a step of computing (c) on the basis of the calculated rate of change, the inductance or capacitance of the series reactance element and shunt reactance element like,
(D) including repeatedly executing steps (a) to (c) until the detection value of the sensor unit reaches the target value.

Preferably, the shunt reactance element includes a first reactance that is shunt-connected between the transmission line and the ground potential, and a reverse reactance that includes a second reactance connected in series between the transmission line and the load. A third reactance connected in series between the L-type matching circuit or the transmission line and the load, and a fourth reactance shunted immediately after the third reactance and between the ground potential and the third reactance. One of the included L-shaped matching circuits .

Preferably, the series reactance element and the shunt reactance element each include a variable capacitance element or a variable inductance element.

  Preferably, the real part and the imaginary part of the impedance or admittance are independently attenuated exponentially with respect to the target value, and the degree of attenuation is designated quantitatively.

  According to this invention, the gain adjustment for determining the convergence speed is performed by automatically specifying the error convergence degree with respect to the target value of the real part and the imaginary part of the impedance or admittance in an exponentially attenuated manner. It can be handled quantitatively, and it becomes possible to optimize the convergence speed of the tuning or impedance adjustment of the transmission line of the high-frequency signal and the load.

The present invention performs system analysis based on modern control theory using state variables, and attenuates exponentially with respect to a target value in an independent form of the real part and imaginary part of admittance or impedance. The degree can be designated quantitatively. First, before describing the embodiment, the principle of the present invention will be described with reference to FIG. In the following description, the transmission line of the matching unit that performs impedance matching is described as the input side, and the end terminal (load) is described as the output side. Here, the end terminal means an oscillator, a receiver, an antenna, a plasma chamber, or the like. In addition, the present invention can be applied even when the input side and the output side are replaced with either the transmission line or the end terminal described above.

FIG. 1 shows an inverted L-type matching circuit, and high frequency power (RF) is supplied to the sensor unit 1. The sensor unit 1 detects the amplitude and phase of the high frequency power and outputs it as impedance. Between the terminals A and the ground potential of the output side of the sensor unit 1, the first reactance X ₁₀ is shunt-connected to a series circuit of a fixed inductance (coil L ₁₎ and a variable capacitance (capacitor C ₁₎ and, between the terminal a and the end terminal 2, the second reactance X ₂₀ is connected to a series circuit of a fixed inductance (coil L ₂₎ and a variable capacitance (capacitor C _2). The capacities of the variable capacitors C ₁ and C ₂ are varied by a drive servo motor (not shown).

Note that the variable element of the first and second reactances X ₁₀ and X ₂₀ may be a variable inductance, and a fixed capacitor may be connected to the variable inductance.

In FIG. 1, the detected impedance value of the sensor unit 1 is represented by Z = (R + jX), and the impedance of the end terminal 2 is represented by Z ₀ = R ₀ + jX ₀ . Further, the variation of the variable capacitance C _1, C ₂ is the assumed to be proportional to the rotation angle of the servo motor for driving the variable capacitance C _1, C ₂ is represented by equation (1).

In the expression (1), r ₁ (t) and r ₂ (t) represent motor rotation speed command values of the variable capacitors C ₁ and C ₂ , respectively. The admittance at point A in FIG.

If the real part and the imaginary part on the left side of the expression (2) are defined as Re and Im, respectively, the expression (2) can be rewritten as the expression (3).

However, X ₁ = ωL ₁ , X ₂ = X ₀ + ωL ₂ . When the derivative is obtained for Re and Im in the expression (3), the expression (4) is obtained.

Here, an error function is defined as in equation (5), and matrix expansion is performed.

Re _ref and Im _ref represent a real part and an imaginary part of the target value, respectively. Here, a diagonal gain matrix shown in the following equation (6) is introduced.

  In this case, if the motor rotation speed command value is obtained as in the following equation (7), the error function e (t) is exponentially attenuated according to the gain matrix K, that is,

In this case, the error function is expressed by the following equation (8).

In the expression (8), k ₁ and k ₂ are gain parameters, respectively.

In the case where the matching circuit is configured by using the inductance elements L ₁ and L ₂ as variable inductance elements, the same error convergence characteristic can be obtained by setting the motor rotation speed command value as shown in Equation (9).

Here, Re and Im are detection values of the sensor unit 1, and Im ₁ is a state quantity that can be calculated from the values of the capacitance C ₁ and the inductance L ₁ , and thus Im ₂ can also be calculated.

1 illustrates an example of an inverted L-type matching circuit, FIG. 2 illustrates an example of an L-type matching circuit. 2, between the terminal A and the ground potential, the third reactance X ₃₀ is connected comprising a series circuit of a fixed inductance in the same manner as in FIG. 1 (a coil L ₁₎ and a variable capacitance (capacitor C ₁₎ However, a fourth reactance X ₄₀ comprising a series circuit of a variable capacitor (capacitor C ₂ ) and a fixed inductance (coil L ₂ ) is connected between the output of the sensor unit 1 and the terminal A.

  In the case of FIG. 2, the equation (10) holds for the impedance Z of the sensor unit 1.

When the derivative is obtained for the resistance R and the reactance X, the expression (11) is obtained.

However, _{X 1} is a reactive part including a capacitor _{C 1, X 2} is a reactance of a portion including a capacitor _{C 2.}

As in the example of FIG. 1, an error function and a gain matrix are introduced as shown in equations (12) and (13).

In this case, if the motor rotation speed command value is determined as shown in Equation (14), the error function e (t) is exponentially attenuated according to the gain matrix K, that is,

In this case, the error function is expressed by equation (15).

Similarly, R and X are the detected value of the sensor unit 1, also the reactance X ₂ can be calculated from the values of the capacitor C ₂ and the coil L _2, hence the state quantity reactance X ₁ can also be calculated.

  In the same way as in the example of FIG. 1, when a matching circuit is configured with a variable inductance as a variable element, the same error convergence characteristic can be obtained by setting the motor rotation speed command value as the following equation (16). Can do.

FIG. 3 is a diagram showing a circuit for impedance matching by the inverted L-type matching circuit shown in FIG. In FIG. 3, the control unit 3 detects the impedance of the sensor unit 1 and performs control for converging impedance matching by changing the capacitances of the capacitors C ₁ and C ₂ . Capacitor C ₁ is driven by a motor M _1, the rotation angle of the motor M _1, i.e. the position is given to the control unit 3 is detected by the potentiometer VRx. Capacitor C ₂ is driven by the motor M _2, the rotation angle of the motor M ₂ is supplied to the control unit 3 is detected by the potentiometer Vry. The fixed inductances of the coils L ₁ and L ₂ are already known.

FIG. 4 is a flowchart for explaining the operation of the impedance matching circuit shown in FIG. In FIG. 4, the control unit 3 sets gain parameters k ₁ and k ₂ in the gain matrix shown in the expression (6) in step (abbreviated as SP in the drawing) SP1. The error function shown in the expression (8) converges exponentially according to the gain parameters k ₁ and k ₂ , and the speed is expressed by a time constant in mathematics. The time constant is the reciprocal of the gain parameters k ₁ and k _2. For example, when k ₁ = 5, the time constant is 0.2 seconds, and when k ₁ = 1, the time constant is 1 second. Therefore, the convergence time constants of e ₂ (t) are 0.2 seconds and 1 second, respectively.

In step SP2, along with the impedance of the sensor unit 1 Z = (R + jX) is detected, the position of the capacitor _{C 1} is detected by the value of the potentiometer VRx.

In step SP3, when the impedance Z is detected, the real part Re and the imaginary part Im shown in the expression (3) are calculated from the reciprocal thereof. Its capacity from position of the capacitor C ₁ is determined, Im ₁ of the equation (3) is calculated. Since L ₁ and L ₂ are known, their numerical values are substituted. Further, a _{Im = Im 1 + Im 2,} Im 2 is computed when Im ₁ is calculated. Thus, detection of the position of the capacitor C ₂ becomes unnecessary. Further, an error vector e (t) defined by the expression (5) is calculated.

In step SP4, the (7) the motor input command value based on equation _r 1 _{(t), r} 2 the vector r (t) calculated in (t), the input command value calculated in step SP5 _r 1 (t) And r ₂ (t), the motors M ₁ and M ₂ are operated. Thereby, the error function e (t) is exponentially attenuated by the expression (8) according to the gain matrix K shown in the expression (6).

  Therefore, according to this embodiment, an inverse L-type matching circuit is connected between the sensor unit 1 and the end terminal 2, and the real part and the imaginary part of the impedance included in the inverse L-type matching circuit are independently set as the target. Since the value is attenuated exponentially and the attenuation can be specified quantitatively, it is easy to optimize the convergence speed of tuning or impedance adjustment between the transmission line of the high frequency signal and the end terminal 2 Can be.

FIG. 5 is a diagram showing a circuit for impedance matching by the L-type matching circuit shown in FIG. In FIG. 5, as in FIG. 3, the control unit 3 detects the impedance of the sensor unit 1 and the end terminal 2 and performs control for converging impedance matching by changing the capacitances of the capacitors C ₁ and C _2. . The capacitors C ₁ and C ₂ are driven by the motors M ₁ and M ₂ , and the rotation angle, that is, the position of the motor M ₁ is detected by the potentiometer VRx and given to the control unit 3. Capacitor C ₂ is driven by the motor M _2, the rotation angle of the motor M ₂ is supplied to the control unit 3 is detected by the potentiometer Vry.

  FIG. 6 is a flowchart for explaining the operation of impedance matching by the L-type matching circuit shown in FIG. In FIG. 6, steps SP11 to SP15 correspond to steps SP1 to SP5 of FIG. 4, and steps SP12 and 13 differ only in the calculation contents of steps SP2 and SP3.

Set the gain parameter _k 1, _{k 2} in step SP11, in step SP 12, along with the impedance of the sensor unit 1 Z = (R + jX) is detected, the position of the capacitor _{C 2} is detected by the value of the potentiometer Vry. In step SP13, the detection value of the sensor unit 1 R and X is substituted to the equation (10), _{X 2} is determined by the value of the potentiometer VRy capacitor _{C 2,} the series combination of capacitor _{C 2} and the coil _{L 2} Calculated as reactance. An error vector e (t) with an error function determined based on the expression (12) is calculated.

In step SP14, a motor input command value vector r (t) is calculated based on the expression (14), and the motor M is calculated according to the input command values r ₁ (t) and r ₂ (t) calculated in step SP15. operating the _first and _{M 2.} As a result, the error function e (t) is exponentially attenuated by the expression (15) according to the gain matrix K shown in the expression (13).

  Therefore, according to this embodiment, an L-type matching circuit is connected between the sensor unit 1 and the end terminal 2, and the real part and the imaginary part of the impedance included in the L-type matching circuit are made independent to the target value. On the other hand, since the attenuation is exponentially performed and the attenuation can be specified quantitatively, it is possible to easily optimize the convergence speed of the tuning or impedance adjustment between the transmission line of the high-frequency signal and the end terminal.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The present invention performs system analysis based on modern control theory using state variables, and attenuates exponentially with respect to a target value in an independent form of the real part and imaginary part of admittance or impedance. Since the degree can be specified quantitatively, it can be used for an impedance matching device of a high-frequency plasma apparatus.

It is a figure which shows an example of a reverse L type | mold matching circuit. It is a figure which shows an example of an L-type matching circuit. It is a figure which shows the circuit which carries out an impedance matching with the inverted L type | mold matching circuit shown in FIG. 4 is a flowchart for explaining an operation of impedance matching by the inverted L-type matching circuit shown in FIG. 3. It is a figure which shows the circuit which carries out impedance matching with the L-shaped matching circuit shown in FIG. 6 is a flowchart for explaining an operation of impedance matching by the L-type matching circuit shown in FIG. 5.

Explanation of symbols

1 sensor unit, second end terminal, 3 control _unit, C 1, _{C 2 capacitors,} L 1, _{L 2 coils,} M 1, _{M 2} motors, VRx, Vry _{potentiometer, X 10} first _{reactance, X 20} second Reactance, X ₃₀ third reactance, X ₄₀ fourth reactance.

Claims (4)

An automatic impedance matching method in which a matching circuit is inserted between a transmission line and a load, and impedance between the transmission line and the load side is matched,
The matching circuit includes a series reactance element connected in series between the transmission line and the load, and a shunt reactance connected in shunt between the input side or output side of the series reactance element and a ground potential line. A sensor unit for detecting either impedance or admittance at least in the power input unit from the transmission line or the power output unit to the transmission line of the matching circuit,
An error function representing a difference between a target value for matching the impedance and a detection value of the sensor unit is defined by a vector represented by a real part variable and an imaginary part variable based on the detection value,
The impedance automatic matching method is:
(A) detecting a detection value of the sensor unit;
(B) Based on the detection value of the sensor unit, the variable of the error function is exponentially attenuated in order to converge the error of the variable indicating the real part of the impedance or admittance and the target value of the variable indicating the imaginary part. The rate of change of the series reactance element and the shunt reactance element for dX / dt = A− ¹ · K · e,
However,
X is a reactance X ₁ of the series reactance element, column vector of the reactance X ₂ of the shunt reactance element,
K is a diagonal matrix whose components are negative,
A represents the relationship between the temporal change, time change of the reactance X ₂ of the reactance X ₁ and the shunt reactance element of the series reactance elements of the error function which is determined from the matching circuit, de / dt = A · a matrix defined by dX / dt,
e is a column vector consisting of real and imaginary parts of the error function,
A step of calculating as follows:
(C) varying the inductance or capacitance of the series reactance element and the shunt reactance element based on the calculated rate of change ;
(D) An automatic impedance matching method including a step of repeatedly executing the steps (a) to (c) until the detection value of the sensor unit reaches the target value. The shunt reactance element is:
An inverted L-type matching circuit including a first reactance shunt connected between the transmission line and a ground potential and a second reactance connected in series between the transmission line and the load; or L-shaped matching including a third reactance connected in series between the transmission line and the load, and a fourth reactance connected immediately after the third reactance and between a ground potential. The automatic impedance matching method according to claim 1, comprising any of the circuits.   The automatic impedance matching method according to claim 1, wherein each of the series reactance element and the shunt reactance element includes a variable capacitance element or a variable inductance element.   The real part and the imaginary part of the impedance or the admittance are independently attenuated exponentially with respect to a target value, and the degree of attenuation is specified quantitatively. Impedance automatic matching method.

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