REGENERATION CIRCULATOR, HIGH-FREQUENCY POWER SUPPLY DEVICE, AND HIGH-FREQUENCY POWER REGENERATION METHOD

Abstract

An excessive voltage rise of load voltage, caused by an impedance mismatching on a transmission path, is prevented, and high-frequency power is regenerated. A parallel impedance is connected to the transmission path during the voltage rise, thereby regenerating voltage caused by a standing wave and preventing excessive load voltage, together with enhancing energy usage efficiency. Establishing the parallel impedance for the load impedance, on the transmission path between the high-frequency amplifier circuit of the high-frequency power supply device and the high-frequency load, reduces impedance at the connecting position to prevent generation of excessive voltage on the transmission path, and high-frequency power is regenerated from the transmission path by the parallel impedance.

Claims

1. A regeneration circulator for regenerating high-frequency power from a transmission path between a high-frequency amplifier circuit of a high-frequency power supply device and a high-frequency load, wherein, an input end of the regeneration circulator is connected at a connecting position on the transmission path, the regeneration circulator configures a parallel impedance for the transmission path, on the basis of a comparison between voltage at the input end of the regeneration circulator and set voltage, and the parallel impedance incorporates the high-frequency power in one direction from the connecting position and regenerates the high-frequency power.

2. The regeneration circulator according to claim 1, wherein, the connecting position on the transmission path where the input end of the regeneration circulator is connected, corresponds to a position indicating an antinode of a standing wave that is generated due to an impedance mismatching on the transmission path, the regeneration circulator configures the parallel impedance for the transmission path on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and the parallel impedance incorporates the high-frequency power in one direction from the connecting position and regenerates the high-frequency power.

3. The regeneration circulator according to claim 1, wherein, the connecting position on the transmission path where the input end of the regeneration circulator is connected, corresponds to a position on the transmission path, indicating an odd multiple of an electrical length being one-fourth wavelength (λ/4) of high-frequency wavelength (λ) that is outputted by the high-frequency power source, the length starting from the output end of the high-frequency amplifier circuit, the regeneration circulator configures the parallel impedance for the transmission path on the basis of the comparison between voltage at the input end of the regeneration circulator and the set voltage, and the parallel impedance incorporates the high-frequency power in one direction from the connecting position and regenerates the high-frequency power.

4. The regeneration circulator according to claim 1, comprising a directional coupler configured to incorporate the high-frequency power in one direction from the transmission path, wherein, the directional coupler incorporates the high-frequency power from the transmission path, on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and while regeneration is performed, the directional coupler configures an upper limit of the voltage at the input end of the regeneration circulator as the set voltage.

5. The regeneration circulator according to claim 4, wherein, the directional coupler comprises a transformer, and a turn ratio of the transformer is a value that is based on a voltage ratio of the set voltage and the voltage at the output end of the regeneration circulator.

6. The regeneration circulator according to claim 5, comprising a rectifier configured to convert AC output from the transformer into DC.

7. The regeneration circulator according to claim 5, wherein, a capacitor is provided in parallel with the secondary side of the transformer.

8. The regeneration circulator according to claim 6, wherein, a DC reactor is provided in series with a subsequent stage of the rectifier.

9. A high-frequency power supply device, comprising, a high-frequency power source configured to feed high-frequency power into a high-frequency load, and a regeneration circulator configured to incorporate high-frequency power in one direction from a transmission path between a high-frequency amplifier circuit provided in the high-frequency power supply device and the high-frequency load, and to regenerate high-frequency power, wherein, an input end of the regeneration circulator is connected to a connecting position on the transmission path, the regeneration circulator configures a parallel impedance for the transmission path on the basis of a comparison between voltage at the input end of the regeneration circulator and set voltage, and the parallel impedance incorporates the high-frequency power from the connecting position and regenerates the high-frequency power.

10. The high-frequency power supply device according to claim 9, wherein, the connecting position on the transmission path where the input end of the regeneration circulator is connected, corresponds to a position indicating an antinode of a standing wave that is generated due to an impedance mismatching on the transmission path, the regeneration circulator configures the parallel impedance for the transmission path on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and the parallel impedance incorporates the high-frequency power from the connecting position and regenerates the high-frequency power.

11. The high-frequency power supply device according to claim 9, wherein, the connecting position on the transmission path where the input end of the regeneration circulator is connected, corresponds to a position on the transmission path, indicating an odd multiple of an electrical length being one-fourth wavelength (λ/4) of high-frequency wavelength (λ) that is outputted by the high-frequency power source, the length starting from the output end of the high-frequency amplifier circuit, the regeneration circulator configures the parallel impedance for the transmission path on the basis of the comparison between voltage at the input end of the regeneration circulator and the set voltage, and the parallel impedance incorporates the high-frequency power in one direction from the connecting position and regenerates the high-frequency power.

12. The high-frequency power supply device according to claim 9, comprising a directional coupler configured to incorporate the high-frequency power in one direction from the transmission path, wherein, the directional coupler incorporates the high-frequency power from the transmission path, on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and while regeneration is performed, the directional coupler configures an upper limit of the voltage at the input end of the regeneration circulator as the set voltage.

13. The high-frequency power supply device according to claim 12, wherein, the directional coupler comprises a transformer, and a turn ratio of the transformer is a value that is based on a voltage ratio of the set voltage and the voltage at the output end of the regeneration circulator.

14. The high-frequency power supply device according to claim 13, comprising a rectifier configured to convert AC output from the transformer into DC.

15. The high-frequency power supply device according to claim 13, wherein, a capacitor is provided in parallel with the secondary side of the transformer.

16. The high-frequency power supply device according to claim 14, wherein, a DC reactor is provided in series with a subsequent stage of the rectifier.

17. A method of regenerating high-frequency power by a regeneration circulator, from a transmission path between a high-frequency amplifier circuit of a high-frequency power supply device and a high-frequency load, comprising, connecting an input end of the regeneration circulator to a position on the transmission path, configuring a parallel impedance for the transmission path, on the basis of a comparison between voltage at the input end of the regeneration circulator and set voltage, and incorporating the high-frequency power in one direction from the connecting position by the parallel impedance and regenerating the high-frequency power.

18. The method of regenerating high-frequency power according claim 17, wherein, the input end of the regeneration circulator is connected to a position on the transmission path, indicating an antinode of a standing wave that is generated due to an impedance mismatching on the transmission path, a parallel impedance is configured for the transmission path on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and the parallel impedance incorporates the high-frequency power in one direction from the connection position and regenerates the high-frequency power.

19. The method of regenerating high-frequency power according to claim 17, wherein, the input end of the regeneration circulator is connected to a position on the transmission path, indicating an odd multiple of the electrical length being one-fourth wavelength (λ/4) of high-frequency wavelength (λ) that is outputted by the high-frequency power source on the transmission path, the length starting from the output end of the high-frequency amplifier circuit, the parallel impedance is configured for the transmission path on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and the parallel impedance incorporates the high-frequency power in one direction from the connecting position and regenerates the high-frequency power.

20. The method of regenerating high-frequency power according to claim 17, wherein, the parallel impedance incorporates the high-frequency power from the transmission path on the basis of the comparison between the voltage at the input end of the regeneration circulator and the set voltage, and while regeneration is performed, an upper limit of the voltage at the input end of the regeneration circulator is configured as the set voltage.

21. The method of regenerating high-frequency power according to claim 17, wherein, AC output of the high-frequency power is converted into DC, and then the high-frequency power is regenerated.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0064] FIG. 1 is a schematic view illustrating a configuration of a regeneration circulator and a high-frequency power supply device of the present invention;

[0065] FIG. 2 is a schematic view illustrating a connecting position of an input end of the regeneration circulator;

[0066] FIG. 3 is a schematic view illustrating a second mode of the connecting position of the input end of the regeneration circulator;

[0067] FIG. 4 illustrates a regenerative operation according to a parallel impedance;

[0068] FIG. 5 illustrates a connection example of the input end of the regeneration circulator;

[0069] FIG. 6 illustrates variation of electrode voltage V.sub.pp with respect to an electrical length;

[0070] FIG. 7 illustrates a circuit example of the regeneration circulator;

[0071] FIG. 8 illustrates circuit examples of the regeneration circulator;

[0072] FIG. 9 illustrates a circuit example of the high-frequency power supply device and the regeneration circulator;

[0073] FIG. 10 illustrates waveforms of voltage and current at each portion of the high-frequency power supply device in a time domain;

[0074] FIG. 11 illustrates waveforms of voltage and current at each portion of the high-frequency power supply device in the time domain;

[0075] FIG. 12 is a Smith chart showing an impedance locus of an output-end impedance Z.sub.amp;

[0076] FIG. 13 is a circuit example of the high-frequency power supply device;

[0077] FIG. 14 illustrates a relationship between regenerative-operation starting voltage V.sub.p-regen and voltage V.sub.P-Z0;

[0078] FIG. 15 illustrates a circuit example of a class-D high-frequency power supply device;

[0079] FIG. 16 illustrates a variation example of output power with respect to variation of impedance Z.sub.amp;

[0080] FIG. 17 illustrates a circuit example of the class-D high-frequency power supply device;

[0081] FIG. 18 illustrates electrode voltage, an impedance, a reflection coefficient ratio with respect to the electrical length; and

[0082] FIG. 19 are schematic views showing the state of standing waves at the time of matching and mismatching.

BEST MODE FOR CARRYING OUT THE INVENTION

[0083] With reference to FIGS. 1 to 4, there will be described a regeneration circulator and a high-frequency power supply device incorporating the regeneration circulator, according to the present invention.

(Configuration of the Present Invention)

[0084] FIG. 1 is a schematic view illustrating a configuration of the regeneration circulator and the high-frequency power supply device of the present invention.

[0085] The high-frequency power supply device 1 is provided with a high-frequency power source 10 and a regeneration circulator 20, and the regeneration circulator 20 being connected to a transmission path 3 of the high-frequency power source 10, establishes a parallel impedance for the transmission path 3, and incorporates power from the transmission path 3 for regenerating power. Regeneration by the regeneration circulator 20 may be executed by returning the incorporated power to the high-frequency power source 10, and in addition, by feeding power into a device not illustrated, or by storing electric power in a storing device not illustrated.

[0086] By way of example, a DC power source 11 and a high-frequency amplifier circuit 12 may constitute the high-frequency power source 10. The high-frequency amplifier circuit 12 performs DC/RF conversion to convert direct current from the DC power source 11 into a high-frequency wave, and raises voltage to output a high-frequency output. The high-frequency output is supplied to a high-frequency load 2 via the transmission path 3.

[0087] The transmission path 3 is a transmission line for supplying power from the output end of the high-frequency amplifier circuit 12 to the input end of the high-frequency load 2, and it may be formed of a power cable disposed between the high-frequency power source 10 and the high-frequency load 2, and wiring and a circuit configuration in the high-frequency power source 10.

[0088] On the transmission path 3, if there is a matching between a characteristic impedance of the transmission path and the impedance of the high-frequency load 2, a forward wave outputted from the high-frequency amplifier circuit 12 may be supplied to the high-frequency load 2 without being reflected. On the other hand, if the impedance of the high-frequency load 2 varies, causing a mismatching between the characteristic impedance of the transmission path and the impedance of the high-frequency load 2, a part or all of the forward wave outputted from the high-frequency amplifier circuit 12 may be reflected, and the forward wave and the reflected wave may form a standing wave.

[0089] The regeneration circulator 20 has a function to establish conduction of current that branches from the transmission path 3, only in one direction; i.e., only in the direction toward the regeneration circulator 20. The circulator within the regeneration circulator represents a function for conducting current with a directionality.

[0090] The regeneration circulator 20 is provided with a regenerating function, in addition to the aforementioned circulator function. The regenerating function of the regeneration circulator 20 may vary the impedance state at a predetermined position on the transmission path 3, between the high-frequency amplifier circuit 12 of the high-frequency power source 10 and the high-frequency load 2, thereby changing the voltage state of the standing wave, and preventing a rise of a voltage standing wave ratio, together with regenerating high-frequency power from the transmission path. The input end of the regeneration circulator 20 is connected onto the transmission path 3, and establishes parallel impedance for the transmission path 3, on the basis of the comparison between the voltage at the input end of the regeneration circulator 20 and preset voltage. The parallel impedance incorporates high-frequency power in one direction from the connecting position on the transmission path 3, and regenerates the high-frequency power.

[0091] During an impedance matching on the transmission path 3, since the voltage at the input end of the regeneration circulator 20 is steady voltage, the voltage is lower relative to the set voltage. In the state of steady voltage, current is not conducted from the transmission path 3 toward the regeneration circulator 20 side, and therefore, the regeneration circulator 20 does not establish the parallel impedance for the transmission path 3.

[0092] When a standing wave is generated on the transmission path 3, the voltage at the input end of the regeneration circulator rises, and it may become higher relative to the set voltage. The standing wave is generated when an impedance mismatching occurs. The voltage at the input end of the regeneration circulator does not necessarily rise every time when the impedance mismatching occurs. There is a possibility that the voltage at the input end of the regeneration circulator is not raised even during the impedance mismatching, depending on the load impedance or an electrical length of the transmission line.

[0093] In the state where the voltage at the input end of the regeneration circulator is higher relative to the set voltage, current is conducted from the transmission path 3 to the regeneration circulator 20 side, and the regeneration circulator 20 establishes parallel impedance for the transmission path 3. The parallel impedance connected to the transmission path 3 may change the impedance state of the transmission path 3, so as to lower the voltage standing wave ratio (VSWR), to prevent a voltage rise, and to incorporates current from the transmission path 3, thereby regenerating power to the DC power source 11. It is to be noted that the power may be regenerated not only into the DC power source 11, but also into other DC power source or storage device.

[0094] The first embodiment and the second embodiment will now be described as to the example how the regeneration circulator is connected to the transmission path 3. A configuration example of the second embodiment corresponds to that of the first embodiment.

First Embodiment

[0095] FIG. 1 shows the first embodiment of a connection between the regeneration circulator and the transmission path. In the first embodiment, the input end of the regeneration circulator 20 is connected to a position corresponding to one of antinode parts of the standing wave that is generated by an impedance mismatching on the transmission path 3. When the standing wave is generated by the impedance mismatching on the transmission path 3, voltage becomes high at the antinode parts, whereas voltage becomes low at node parts. FIG. 1 shows a configuration example where the input end of the regeneration circulator 20 is connected to the antinode parts of the standing wave on the transmission path 3.

[0096] By connecting the input end of the regeneration circulator 20 to the antinode parts where high voltage is generated on the transmission path 3, the regeneration circulator 20 incorporates current from the antinode part on the transmission path 3, and when thus incorporated voltage exceeds the set voltage, parallel impedance is established for the transmission path 3.

Second Embodiment

[0097] FIG. 2 is a schematic view describing the second embodiment of the connection between the regeneration circulator and the transmission path, and FIG. 2 shows an example where the input end of the regeneration circulator is connected to a position indicating a predetermined electrical length from the output end of the high-frequency amplifier circuit. In FIG. 2, the connecting position of the input end of the regeneration circulator 20 is represented by P, and the impedance at the position P is represented by Z.sub.P.

[0098] In FIG. 2, in a high-frequency power source 10 the transmission line 4 with the characteristic impedance Z.sub.0 connects the high-frequency power source 10 with the high-frequency load 2, and the high-frequency amplifier circuit 12 is connected to an output circuit 13, provided with an impedance matching at Z.sub.0. With this impedance matching at Z.sub.0 in the output circuit 13, the impedance Z.sub.amp when viewing the load side from the high-frequency amplifier circuit 12, matches the impedance Z.sub.g0 at the output end of the high-frequency power source 10.

[0099] When the high-frequency load is in a short-circuited state or in the open state, an impedance mismatching occurs on the transmission path, causing a reflected wave, and accordingly, a standing wave is formed. The second embodiment shows the state where the high-frequency load is short-circuited state.

[0100] The second embodiment is directed to reducing the standing wave that is generated when the end of the transmission path is in a short-circuited state, and the input end of the regeneration circulator 20 is connected to a position indicating an odd multiple of an electrical length being one-fourth wavelength (λ/4) of the high-frequency wavelength (λ) on the transmission path 3, the length starting from the output end (the position of impedance Z.sub.amp) of the high-frequency amplifier circuit 12, and the high-frequency wave being outputted from the high-frequency power source 10.

[0101] FIG. 3 illustrates the case where the input end of the regeneration circulator 20 is connected to the position indicating an odd multiple of an electrical length being one-fourth wavelength (λ/4) of the high-frequency wavelength (λ), from the output end of the high-frequency amplifier circuit 12 on the transmission path 3. The connecting position is represented by (2n−1)λ/4, where n is integer.

[0102] FIG. 3A illustrates the state where the regeneration circulator establishes a parallel impedance, when the impedance Z.sub.L of the high-frequency load is in a short-circuited state, FIG. 3B illustrates a standing wave that is generated when the impedance Z.sub.L of the high-frequency load is in a short-circuited state, and FIG. 3C shows a standing wave caused by the parallel impedance during the regenerative operation.

[0103] When the end of the transmission path is in a short-circuited state, an impedance mismatching occurs and a standing wave is generated. In this case, the position indicating an odd multiple of an electrical length being one-fourth wavelength (λ/4) of the high-frequency wavelength (λ) outputted from the high-frequency power source on the transmission path, corresponds to an antinode part of the standing wave, and therefore voltage is high. In here, the electrical length starts from the output end of the high-frequency amplifier circuit being the end point. As for the voltage and current shown in FIG. 3B and FIG. 3C, the voltage is indicated by a solid line and the current is indicated by a broken line when the end of the transmission path is short-circuited. FIG. 3B shows the state before regeneration, and FIG. 3C shows the state after regeneration.

[0104] The input end of the regeneration circulator is connected to the position indicating an electrical length where high voltage is generated on the transmission path, then the regeneration circulator incorporates current from the high voltage part on the transmission path, and establishes parallel impedance for the transmission path, when the incorporated voltage exceeds preset voltage. FIG. 3 shows an example where voltage being k-times larger than the voltage V.sub.L on the high-frequency load is assumed as the preset voltage. It is to be noted that the standing wave voltage is zero at the end being in a short-circuited. In this example, it is assumed that on the load side, the voltage at the position corresponding to the antinode part of the standing wave indicates voltage V.sub.L on the high-frequency load side.

[0105] The regeneration circulator being connected establishes the parallel impedance Z.sub.R, and with this impedance, the peak value of the standing wave is reduced, and then the voltage V.sub.L on the high-frequency load side is also reduced.

[0106] FIG. 4 illustrates the regenerative operation according to the parallel impedance. In this example, the voltage being k-times larger than the load voltage V.sub.L is used as the set voltage for performing the regenerative operation. In FIG. 4A, the voltage V.sub.P at the connecting position P of the regeneration circulator corresponds to the steady voltage that is determined on the basis of the matched impedance, during the state of impedance matching, whereas during the mismatching state, the impedance Z.sub.amp at the output end of the high-frequency amplifier circuit is reduced from Z.sub.0, resulting in a rise of voltage. When the voltage V.sub.P exceeds the set voltage k.Math.V.sub.L, the regenerative operation of the regeneration circulator is started, and then current passes into the circulator from the transmission path (FIG. 4B).

[0107] The regeneration circulator operates as the parallel impedance Z.sub.R according to the regenerative operation (FIG. 4C). When the parallel impedance Z.sub.R is connected to the impedance Z.sub.g0 at the output end of the high-frequency power supply device, impedance is increased, and then, the impedance Z.sub.amp having been reduced at the output end of the high-frequency amplifier circuit is enabled to prevent a voltage rise of the voltage V.sub.P (FIG. 4D). It is to be noted that the impedance Z.sub.amp during the regenerative operation does not exceed the value that is obtained under normal operating conditions.

(Configuration Example)

[0108] With reference to FIGS. 5 to 8, a configuration example of the second embodiment will now be described, as to the regeneration circulator and the high-frequency power supply device.

[0109] FIG. 5 illustrates a configuration example where the input end of the regeneration circulator 20 is connected at the position indicating the electrical length of (2n−1)λ/4 from the output end of the high-frequency amplifier circuit 12. In the high-frequency power supply device 1, a bridge circuit 12a of semiconductor switching elements and a transformer 12b constitute the high-frequency amplifier circuit 12. The output circuit 13 comprises a series connection circuit between a matching circuit 13a that performs impedance matching with the characteristic impedance Z.sub.0 of the transmission line 4 and an LPF (low-pass filter) 13b for removing a noise component. An LC circuit, for instance, may constitute the matching circuit 13a. The LC circuit and the LPF (low-pass filter circuit) 13b are designed in such a manner that the electrical length becomes equal to (2n−1)λ/4.

[0110] When AC voltage at the input end of the regeneration circulator 20 exceeds a certain level, current starts to pass into the circuit of the regeneration circulator. Therefore, the load (impedance) is seemingly connected to the circuit of the regeneration circulator 20 in parallel, and accordingly, this leads to an operation to prevent the connecting position of the regeneration circulator from becoming high impedance. At the same time, this operation similarly indicates that the impedance Z.sub.amp at the point of the electrical length (2n−1)λ/4 from the regenerative circuit is prevented from becoming low impedance.

[0111] The regeneration circulator 20 is a circuit to start regenerating regeneration circulator power, and as shown in FIG. 1 and FIG. 2, it is provided with a directional coupler 21 for incorporating high-frequency power in one direction from the transmission path and a rectifier circuit 22. The directional coupler 21 incorporates high-frequency power from the transmission path, on the basis of comparison between the voltage at the input end of the regeneration circulator 20 and the set voltage, and during the regenerative operation, the upper limit of the voltage at the input end of the regeneration circulator is configured as the set voltage. The rectifier circuit 22 converts AC to DC, and regenerates the DC into a DC power source 11, and the like.

[0112] FIG. 6 shows that the high-frequency amplifier circuit including the transformer 12b with the turn ratio of 1:2 as shown in FIG. 5, is connected to a circuit of the output circuit 13, and assuming the case where plasma is extinguished with an active component of the load impedance Z.sub.L being 100 kΩ (≈Open), two situations are illustrated; one is when the regeneration circulator is provided, and the other is when it is not provided for the electrode voltage V.sub.pp, where the electrical length l of the transmission path varies from 0 degree angle to 180 degree angle. The electrode voltage V.sub.pp in FIG. 6 indicates that the regenerative operation is performed within the range of the electrical length from approximately 85 degree angle to 125 degree angle, so as to reduce the electrode voltage V.sub.pp.

[0113] FIG. 7 and FIG. 8 show circuit configurations of the regeneration circulator. In the circuit example as shown in FIG. 7, the regeneration circulator 20 is provided with a transformer 20a on the input side, and a rectifier 20b comprising a diode bridge circuit on the output side. The transformer 20a is associated with the directional coupler 21, and the rectifier 20b is associated with the rectifier circuit 22. By way of example, the output side is connected to a DC voltage source of the DC power source 11, thereby regenerating the DC power into the DC voltage source. It is to be noted that the DC power may be regenerated not only into the DC voltage source of the high-frequency power supply device, but also into other DC voltage source.

[0114] FIG. 8 shows modified circuit examples of the regeneration circulator. The circuit example as shown in FIG. 8A connects a capacitor 20c to the secondary side of the transformer constituting the transformer 20a, thereby compensating for voltage-waveform distortion on the secondary side of the transformer, caused by a commutation overlap angle due to leaked current (leakage) passing through the transformer.

[0115] In the circuit examples as shown in FIG. 8B and FIG. 8C, inductances 20d and 20e are connected on the output side of the diode bridge, thereby reducing an AC component directed to the DC power source (V.sub.DD) being a destination of regeneration. Another example may be possible where the capacitor in FIG. 8A and the inductance as shown in FIG. 8B or FIG. 8C are combined.

(Operation Example)

[0116] With reference to FIGS. 9 to 13, operation examples of the regeneration circulator of the present invention will now be described.

[0117] FIG. 9 is a circuit example of the high-frequency power supply device and the regeneration circulator. In the circuit example of FIG. 9, there are shown parameters as the following; in the steady state where plasma is ignited, and in the abnormal state where plasma is extinguished for the cases where the regeneration circulator is provided and not provided. It is to be noted that the load impedance Z.sub.L is 50Ω and the active component R.sub.L is 100Ω, when plasma is ignited.

[Steady State]

[0118] DC power source voltage V.sub.DD: 290 V
Forward wave: 4,000 W (measured value at the output end of high-frequency power supply device)
Reflected wave: 0 W (measured value at the output end of high-frequency power supply device)
Output-end impedance Z.sub.amp of high-frequency amplifier circuit: 40+j20Ω
Voltage V.sub.pp of active components R.sub.L of load impedance: 1,794 V
Active component R.sub.L of load impedance: 100Ω
Output-end impedance Z.sub.g0 of high-frequency power supply device: 50Ω

[Abnormal State: Regeneration Circulator is not Provided]

[0119] In the circuit example of FIG. 9, when the regeneration circulator is not provided, parameters in the abnormal state where plasma is extinguished are as the following. It is to be noted that the active component R.sub.L of the load impedance is 100 kΩ when plasma is extinguished.

DC power source voltage V.sub.DD: 290 V
Forward wave: 49,000 W (Measured value at the output end of high-frequency power supply device)
Reflected wave: 49,000 W (Measured value at the output end of high-frequency power supply device)
Output-end impedance Z.sub.amp of high-frequency amplifier circuit: 0.05−j0.01Ω
Voltage V.sub.pp of active component R.sub.L of load impedance: 12,530 V
Active component R.sub.L of load impedance: 100 kΩ
Output-end impedance Z.sub.g0 of high-frequency power supply device: open (40 kΩ)

[0120] FIG. 10 shows waveforms within a time domain, respectively of the output-end voltage V.sub.g0 of the high-frequency power supply device, the electrode voltage V.sub.pp, the output current I.sub.dc from the DC power source, and the input voltage I.sub.inv into the high-frequency amplifier circuit. FIG. 10 illustrates data when plasma is extinguished at t=12 us.

[0121] In the case where the regeneration circulator is not provided, output power of 49 kW is outputted to 4-kW rated power source, and there is a possibility that power amplifier element is broken due to over voltage or excessive loss. In addition, the electrode voltage V.sub.pp at the steady time is 1,794 V, whereas at the abnormal time, high voltage of 12,530 V is applied to the electrodes within the vacuum device, and there is a problem that this high voltage may be a factor of arching generation due to an electrode fracture or dielectric breakdown.

[Abnormal State: Regeneration Circulator is Provided]

[0122] In the circuit example as shown in FIG. 9, when the regeneration circulator is provided, parameters in the abnormal state where plasma is extinguished are as the following. When plasma is extinguished, the active component R.sub.L of the load impedance is assumed as 100 kΩ.

DC power source voltage V.sub.DD: 290 V
Forward wave: 4,000 W (measured value at the output end of high-frequency power supply device)
Reflected wave: 4,000 W (measured value at the output end of high-frequency power supply device)
Output-end impedance Z.sub.amp of high-frequency amplifier circuit: 18.9+j6.0Ω
Voltage V.sub.pp of active component R.sub.L of load impedance: 3,560 V
Active component R.sub.L of load impedance: 100 kΩ
Output-end impedance Z.sub.g0 of high-frequency power supply device: open (40 kΩ)

[0123] FIG. 11 shows waveforms within the time domain, respectively of the output-end voltage V.sub.g0 of the high-frequency power supply device, the electrode voltage V.sub.pp, the output current I.sub.dc of the DC power source, and the input voltage I.sub.inv into the high-frequency amplifier circuit. FIG. 11 illustrates data when plasma extinguished at t=12 us.

[0124] FIG. 12 illustrates on the Smith chart, an impedance locus of the output end impedance Z.sub.amp with respect to the electrical length of the transmission line. FIG. 12A shows variation of the output end impedance Z.sub.amp when plasma is extinguished, without the regeneration circulator. FIG. 12B shows variation of the output end impedance Z.sub.amp when plasma is extinguished, with the regeneration circulator being provided.

[0125] In FIG. 12A, the reference symbols A, B, and C correspond to the impedance, respectively when the electrical length is 0, λ/4, and λ/2, and in accordance with the variation of the electrical length from 0 to λ/2, the impedance varies in the order of A, B, and C.

[0126] Since there is a relationship of λ/4 in electrical length, between the antinode part and the node part of the standing wave, the load-end voltage is maximized when the load end is located at the position corresponding to the antinode part of the standing wave. In this situation, the impedance Z.sub.amp viewed from the high-frequency amplifier circuit, in association with the node part of the standing wave is low impedance, which corresponds to the impedance in the short-circuited state. Since the load end voltage is proportional to the electrode voltage, when the electrode voltage is maximized, the impedance Z.sub.amp becomes low.

[0127] In FIG. 12A, when the load end voltage (electrode voltage) is maximized, the impedance at the load end is located at the electrical length A, and the impedance Z.sub.amp viewed from the high-frequency amplifier circuit is located at the electrical length B, moved only by λ/4 from the position A. The impedance of the electrical length B is zero, and this corresponds to the short-circuited state.

[0128] Therefore, observing the impedance Z.sub.amp viewed from the high-frequency amplifier circuit, when the impedance Z.sub.amp is located at the electrical length B where the impedance is zero, the impedance at the load end is located at the electrical length A, where the impedance corresponds to co, and the load end voltage (electrode voltage) increases.

[0129] In FIG. 12B, the reference symbols A and C correspond to the impedance, respectively when the electrical length is zero 0 and λ/2, D corresponds to the impedance when the electrical length is between 0 and λ/4, E corresponds to the impedance when the electrical length is between λ/4 and λ/2, and the impedance varies in the order of A, D, E, and C, along with the variation of the electrical length from 0 to λ/2.

[0130] In the configuration where the regeneration circulator is provided, when the impedance Z.sub.amp is coming into the short-circuited state, between 0 and λ/4, the parallel impedance becomes connected to the transmission path at the electrical length D. Then, another active component may be generated, in addition to those provided in the load impedance, and the impedance may vary along with the impedance locus that avoids the low impedance point at the electrical length B.

[0131] When the impedance Z.sub.amp returns from the short-circuited state to the open state, between λ/4 and λ/2, the parallel impedance is disconnected from the transmission path, and the active component being generated disappears at the electrical length E, and the impedance varies toward the high impedance point at the electrical length C.

[0132] Therefore, with the regeneration circulator, it is possible to allow the output end impedance Z.sub.amp of the high-frequency amplifier circuit to be away from the low impedance of the short-circuited state.

[0133] Since the parallel impedance according to the regeneration circulator allows the impedance Z.sub.amp to be away from becoming low impedance, it is possible to prevent the load voltage V.sub.L and the electrode voltage V.sub.pp from boosting up to be a value several ten folds larger than a value in the steady state.

[0134] The active component caused by the parallel impedance is generated by resuming power in the DC power source voltage V.sub.DD via the regeneration circulator, and it is not generated by adding a loss component such as an internal dummy load. Therefore, it is possible to avoid a loss of energy being regenerated, thereby enhancing the regenerative efficiency.

[0135] In addition, the output power at the time of total reflection time is limited to 4,000 W, and as a result, the upper limit of the electrode voltage V.sub.pp is also restricted.

[0136] By setting the upper limit of the output power and voltage, it is possible to prevent a fracture of the power amplifier element, electrode breakage of the vacuum device, a fracture of a semiconductor element due to arching, and the like.

(Condition for Starting the Regenerative Operation)

[0137] As described above, the impedance state where the impedance Z.sub.amp viewed from the output end of the high-frequency amplifier circuit becomes low, is associated with a rise of the load end voltage caused by a standing wave. There will now be described an operating condition that prevents the impedance Z.sub.amp from becoming low according to the regenerative operation.

[0138] The class-D high-frequency power supply device generates a square wave by an inverter. In the circuit example of FIG. 13, the internal resistance R.sub.in is expressed by the following formula, where an effective value voltage of a basic wave component of the square wave voltage is V.sub.in, on-resistance of the inverter is R.sub.on, and the transformer turn ratio is N:

R.sub.in=2R.sub.onN.sup.2  (1)

[0139] In this case, a relationship between an effective value voltage V.sub.g0 and an effective value current i.sub.g0 of high-frequency output is expressed as:

v.sub.amp=v.sub.g0=v.sub.in−R.sub.ini.sub.amp=v.sub.in−R.sub.ini.sub.g0

i.sub.amp=i.sub.g0

Z.sub.amp=v.sub.amp/i.sub.amp=V.sub.g0/i.sub.g0=Z.sub.g0  (2)

[0140] Following formulas are established, where the effective value voltage on the load side at the coaxial cable length l is V.sub.L, the effective value current is i.sub.L, the transmission path length is 1=λ/4 and βl=π/2, V.sub.L substitutes for V.sub.L (λ/4), assuming V.sub.L (λ/4)=V.sub.L-set where V.sub.L(λ/4) is set as a reference vector:

v.sub.L-set=v.sub.P-set

i.sub.L-set=i.sub.P-set

Z.sub.L=Z.sub.P  (3)

V.sub.g0(λ/4)=j(V.sub.P-setZ.sub.0)/Z.sub.P

i.sub.g0(λ/4)=jv.sub.P-set/Z.sub.0

Z.sub.g0(λ/4)=V.sub.g0(λ/4)/i.sub.g0(λ/4)=Z.sub.0.sup.2/Z.sub.P  (4)

[Allowable Voltage Ratio k and Z.SUB.amp .During the Regenerative Operation]

[0141] In the formula 4, the subscript at the time of impedance matching where Z.sub.L=Z.sub.0 is represented as “.sub.Z0”, the subscript during the regenerative operation is represented as “.sub.regen”, and when the allowable voltage ratio k of the load voltage V.sub.L is defined, assuming that the regenerative operation starts when the load voltage V.sub.L becomes k times larger than the load voltage V.sub.L-Z0 at the time of impedance matching, the impedance Z.sub.amp(λ/4)-regen viewed from the high-frequency amplifier circuit at the time of regeneration, and the impedance Z.sub.P(λ/4)-regen at the connecting position P of the regeneration circulator are expressed respectively as the following:

Z.sub.amp(λ/4)-regen={Z.sub.0−(k−1)R.sub.in}/k

Z.sub.P(λ/4)-regen=kZ.sub.0.sup.2/{Z.sub.0−(k−1)R.sub.in}  (5)

[0142] When the electrical length between the connecting position P of the regeneration circulator and the load end has an integral multiple relation in terms of the wavelength λ, this leads to a relation of V.sub.L=V.sub.P. Therefore, the allowable voltage ratio k can be set by the voltage V.sub.P at the connecting position P, instead of the load voltage V.sub.L, and the allowable voltage ratio k may be configured in such a manner that the regenerative operation starts when the regenerative-operation starting voltage V.sub.P-regen becomes k times larger than the voltage V.sub.P-Z0 at the time of impedance matching. FIG. 14 shows a relation between the regenerative-operation starting voltage V.sub.P-regen and the voltage V.sub.P-Z0, where the allowable voltage ratio k is 2.

[0143] Under the following condition for maximizing the load voltage v.sub.L, as a calculation example,

Z.sub.L=∞

R.sub.in=8Ω

Z.sub.0=50Ω, and

[0144] Electrical length of the transmission line l=λ/4; there will now be described an example for reducing the load voltage V.sub.L, where k=2 with the use of the regeneration circulator.

[0145] In the state where the impedance Z.sub.P on the load side relative to the connecting position P of the regeneration circulator is open (Z.sub.P=∞) on the load side, the impedance Z.sub.P becomes Z.sub.P=Z.sub.R according to image impedance, when the parallel impedance Z.sub.R is connected by the regeneration circulator.

[0146] Here, Z.sub.amp and Z.sub.P are obtained by using the formula 5 as the following:

Z.sub.amp={Z.sub.0−(k−1)R.sub.in}/k={50−(2−1)×8}/2=21[Ω]

Z.sub.P=Z.sub.R=kZ.sub.0.sup.2/{Z.sub.0−(k−1)R.sub.in}=2×50.sup.2/{50−(2−1)×8}≈119[Ω]

[0147] This indicates that Z.sub.R (approximately 119Ω) is connected in parallel with the infinite load impedance at the point P, then preventing Z.sub.amp from becoming low impedance (short-circuited).

[0148] In the formula 5, even when the load is in the open state (Z.sub.L=∞), the allowable voltage ratio k is set to 1, thereby establishing Z.sub.amp=Z.sub.P=50Ω and leading to the state of impedance matching.

[0149] The allowable voltage ratio k=1 indicates that the load voltage V.sub.L for starting the regenerative operation is set to be the load voltage V.sub.L−Z.sub.0 of impedance matching, and by performing the regenerative operation even during the normal state, it is possible to maintain the load voltage V.sub.L to be the load voltage V.sub.L−Z.sub.0 of impedance matching, against abnormality caused by an impedance mismatching.

[Relation Between V.sub.L-regen During Regenerative Operation and DC Power Source Voltage V.sub.DD]

[0150] When the load voltage V.sub.L becomes k times larger than the effective value voltage V.sub.L−Z.sub.0 of impedance matching, the regenerative operation is started to perform regeneration of DC power into the DC power source voltage V.sub.DD. Simultaneously, the upper-limit of the load voltage V.sub.L is restricted to the load voltage V.sub.L-regen for the regenerative operation.

[0151] In the case where the regeneration is performed by using the transformer, the DC power source voltage V.sub.DD being a regenerating destination may be defined by an average value (2√2v.sub.P-regen/π) of V.sub.P-regen(V.sub.L-regen), and the turn ratio N of the transformer.

[0152] When Z.sub.L is equal to Z.sub.0, if the DC power source voltage V.sub.DD applied to the inverter of the high-frequency amplifier circuit and the regenerative-operation starting voltage V.sub.P-z0 (V.sub.L-z0) are already known, the turn ratio N of the transformer may be expressed by the following formula 6, using the allowable voltage ratio k:

N×V.sub.DD=2√2×V.sub.L-regen/π=(2√2×k×v.sub.L-z0))/π

N=(2√2×k×V.sub.L-Z0)/(π×V.sub.DD)≈(0.9×k×v.sub.L-Z0)/((π×V.sub.DD)  (6)

[0153] The descriptions of the above embodiments and modifications are intended to illustrate the DC generator and the method of controlling the DC generator as an example relating to the present invention, and the present invention is not limited to those embodiments. More specifically, it is intended that the invention embrace all modifications and variations of the exemplary embodiments described herein that fall within the spirit and scope of the invention.

Industrial Applicability

[0154] The regeneration circulator, the high-frequency power supply device, and the regeneration method according to the present invention are applicable to a power supply unit and a power supply method for supplying high-frequency power to a load device being a plasma load, such as liquid-crystal panel manufacturing equipment, semiconductor producing equipment, and laser oscillator.

DESCRIPTION OF SYMBOLS

[0155] A to E electrical length [0156] I.sub.dc output current [0157] I.sub.g0 current [0158] I.sub.inv input voltage [0159] N turn ratio [0160] P connecting position [0161] R.sub.L active component [0162] R.sub.in internal resistance [0163] R.sub.on resistance value [0164] V.sub.DD DC power source voltage [0165] V.sub.L load voltage [0166] V.sub.P regenerative-operation starting voltage [0167] V.sub.g0 output end voltage [0168] V.sub.in AC voltage source [0169] V.sub.pp electrode voltage [0170] Z.sub.0 characteristic impedance [0171] Z.sub.L load impedance [0172] Z.sub.P impedance [0173] Z.sub.R parallel impedance [0174] Z.sub.amp output end impedance [0175] Z.sub.g0 output end impedance [0176] i.sub.L effective value current [0177] i.sub.g0 effective value current [0178] k allowable voltage ratio [0179] v.sub.L load voltage [0180] Γ voltage reflection coefficient [0181] λ wavelength [0182] 1 high-frequency power supply device [0183] 2 high-frequency load [0184] 3 transmission path [0185] 4 transmission path [0186] 10 high-frequency power source [0187] 11 DC power source [0188] 12 high-frequency amplifier circuit [0189] 12a bridge circuit [0190] 12b transformer [0191] 13 output circuit [0192] 13a LC circuit [0193] 13b LPF [0194] 20 regeneration circulator [0195] 20a transformer [0196] 20b rectifier [0197] 20c capacitor [0198] 20d, 20e inductance [0199] 20f voltage divider [0200] 21 directional coupler [0201] 22 rectifier circuit [0202] 101 generator [0203] 102 load [0204] 104 transmission path [0205] 111 DC power source [0206] 112 high-frequency amplifier circuit [0207] 112a bridge circuit [0208] 112b transformer [0209] 113 output circuit [0210] 113a matching circuit [0211] 113b filter circuit