JP6322990B2 - Inverter device and plasma generator - Google Patents

Description

  The present invention relates to an inverter device and a plasma generator using it as a power source.

A switching regulator and an inverter device are used to supply a high voltage to various devices such as a discharge tube for a large plasma display and a plasma generator.
Generally, an output power value of about several watts is often used, but an inverter device having an AC output with an output voltage of several tens of KV and a power value of several tens of watts or more is used for a plasma generator or the like. Is done.

In general switching regulators (AC or DC-DC converters), a DC voltage is switched by a switching element intermittently applied to the primary excitation winding of a voltage conversion transformer, and applied to a secondary output winding. The generated AC current is rectified and smoothed to output a DC voltage.
In order to maintain the output voltage at a constant voltage, as seen in Patent Document 1, for example, the output voltage is detected to generate a feedback voltage. Thereby, pulse width modulation (PWM) control is performed to control the ratio (duty ratio) between the ON time and OFF time of the switching element.

When the output voltage drops, the ON width of the switching pulse is widened to compensate for the output power shortage. Conversely, when the output voltage rises, the ON width is narrowed to limit the excess output power. The voltage is controlled to be constant.
In addition, the inverter device intermittently applies a DC voltage to the excitation winding on the primary side of the voltage conversion transformer by a switching element in the same manner as described above, and generates an AC voltage generated on the output winding on the secondary side. Output to the load as it is.

  When the output voltage is a DC switching regulator, as described in Patent Document 1, it is possible to detect the output voltage and perform PWM control of a switching pulse for ON / OFF control of the switching element. Further, since there is a holding time due to an electrolytic capacitor of the output smoothing circuit, control responsiveness does not become a problem.

However, since the output of the inverter device is alternating current, it is difficult to control the peak value (peak voltage value) to be constant regardless of whether it is full wave or half wave.
The reason is that the peak time is one point, there is a control delay, the higher the frequency at which the output voltage waveform is repeated, the more the influence of the delay becomes, and the peak voltage drops. It is because it passes too much and rises too much.

  When the output is alternating current, the switching frequency is as high as several tens of KHz, and the peak value voltage of the output is as high as several tens of KV, in addition to the above-mentioned control responsiveness problem, output voltage detection means and components There arises a problem of the withstand voltage. Therefore, in an inverter device that outputs such a high voltage, it is general that the output voltage value is not controlled only by controlling the input supply voltage to be constant.

  In this case, for example, as can be seen in Japanese Patent Application Laid-Open No. H10-228707, there is a type in which an output current is detected instead of an output voltage and the voltage is replaced with a voltage to perform PWM control on the switching element. However, the peak value of the output voltage is not monitored and cannot be controlled.

  Therefore, Patent Document 3 proposes an invention for controlling the peak value voltage to be constant in a high voltage inverter device having an output of alternating current and a peak value voltage of several tens KV. The high voltage inverter device uses a voltage generated between terminals of a switching element for switching an exciting current or between both ends of an exciting winding as a monitor voltage.

  The output voltage control circuit switches the switching element according to the peak value of the monitor voltage from the time when the half wave of the monitor voltage is completed in the OFF period of the switching element until just before the second harmonic of the resonance voltage appears. A control signal for controlling when to turn on is generated. The PWM control circuit inputs the control signal, and the pulse width modulation is performed so that the switching pulse by the rectangular wave pulse signal having a constant frequency is changed in accordance with the control signal. Output. Thereby, on / off of the switching element is controlled to control the peak value voltage of the AC output voltage to be constant.

However, even such an inverter device has the following problems when used as a power supply device of a plasma generator, for example.
As plasma discharge, for example, atmospheric pressure plasma discharge is generally said to occur when a voltage of 6 KV or higher is applied under normal pressure conditions. As means for realizing the atmospheric pressure plasma discharge, there are dielectric barrier discharge, silent discharge, corona discharge in the atmosphere, and the like.
When such plasma discharge is used for surface treatment of recording materials used for so-called printing such as paper, active species such as radicals and ions generated by the discharge are important for surface modification of the recording material. Play an important role.

However, the active species generated by the discharge pulse decreases in a very short time after generation. Therefore, in order to enhance the effect of surface modification on the recording material to be surface-treated, it is necessary to continuously generate active species and keep the concentration of the active species uniform.
As a method of generating active species continuously, it is conceivable to increase the number of discharges by increasing the switching speed of the primary side of the transformer in the inverter device . However, this causes a problem of heat generation of the transformer and the switching element.

As another method for continuously generating active species, it is conceivable to increase the amount of active species generated per discharge by increasing the output voltage of the inverter device and increasing the discharge current. However, if the output voltage is set higher than the intended use, discharge may occur in an unexpected place. Moreover, the energy consumption of the system will be increased more than necessary, which is not preferable from the viewpoint of energy saving.
In the high-voltage inverter device disclosed in Patent Document 3, such a problem has not been considered.

  The present invention has been made in view of such a current situation, and when applied to an apparatus for generating plasma discharge, the plasma generating apparatus generates continuous and uniform active species, and more than necessary. An object of the present invention is to provide an inverter device that does not increase energy consumption by the system.

In order to achieve the above object, the present invention switches direct voltage or an input voltage in which a pulsating current is superimposed on a direct current component, causes an exciting current to flow in the exciting winding of the transformer, and outputs an alternating voltage from the output winding of the transformer. In the inverter device that outputs the above, each of the transformers is composed of one or more transformers, and the first transformer group and the second transformer group that have different characteristics due to different inductances of the output windings .
The excitation windings of the transformers of the first and second transformer groups are connected in parallel or in series so that the excitation current flows simultaneously.
Further, when each of the first and second transformer groups is composed of one transformer, the output winding of the one transformer is used as the output winding of each transformer group, and when each of the transformers is composed of a plurality of transformers. The output windings of the transformers are connected in series to form output windings of the transformer groups, and the output windings of the first transformer group and the output windings of the second transformer group are connected in parallel. It is connected, and the waveform of the output voltage to the load is dispersed and output in at least two or more within the switching period.

  The inverter device according to the present invention can disperse the output waveform of the output AC voltage. Therefore, when applied to an apparatus for generating plasma discharge, the plasma generating apparatus can continuously generate uniform active species and does not increase the energy consumption by the system more than necessary.

1 is a circuit diagram schematically showing a first embodiment of an inverter device and a plasma generator according to the present invention. FIG. 2 is a circuit diagram showing a connection relationship on a secondary side of a transformer in the inverter device shown in FIG. 1. It is a figure for demonstrating the example of an output voltage waveform at the time of assuming that only the output winding of the trans | transformer T1 in FIG. 2 and the discharge part are connected in parallel. It is a figure for demonstrating the example of an output voltage waveform at the time of assuming that only the output winding of the trans | transformer T2 in FIG. 2 and the discharge part are connected in parallel. It is a figure for demonstrating the example of the output voltage waveform in the case of the connection state shown in FIG.

A waveform diagram for explaining the outline of the ON / OFF signal, output voltage waveform, and amount of active species of the switching element when the output windings of two transformers having the same characteristics are connected in series and the outputs are stacked. is there. A waveform diagram for explaining the outline of the ON / OFF signal of the switching element, the output voltage waveform, and the amount of active species when the output windings of two transformers having different characteristics are connected in parallel and the outputs are added. is there. It is a wave form diagram which shows the relationship between the period between the distributed output voltage waveforms, and the quantity of active species.

It is a circuit diagram which simplifies and shows 2nd Embodiment of the inverter apparatus and plasma generator by this invention. It is a circuit diagram which simplifies and shows 3rd Embodiment of the inverter apparatus and plasma generator by this invention. It is a circuit diagram which simplifies and shows an example of the plasma generator using the inverter apparatus made into the object of this invention. It is a wave form diagram which shows the voltage of each part in the inverter apparatus of FIG. It is a side view which shows typically the structural example of the discharge part in FIG.

[Example of plasma generator using inverter device]
Prior to the description of embodiments for carrying out the present invention, an example of a plasma generator using an inverter device as an object of the present invention will be described.
FIG. 11 is a circuit diagram showing a simplified example of the plasma generating device, and FIG. 12 is a waveform diagram showing voltage and current waveforms of each part in the inverter device.
A plasma generator 100 shown in FIG. 11 includes an inverter device 10 and a discharge unit 20 as a load thereof.

The inverter device 10 uses, as an input voltage Vin, a rectifying / smoothing circuit 12 that rectifies and smoothes an AC voltage from a commercial power supply 11 and a DC voltage (which may include a pulsating current component) output from the rectifying / smoothing circuit 12. A transformer 13, a switching element Q such as an FET, and a control circuit 15 are provided.
The transformer 13 has an excitation winding Np and an output winding Ns, and the excitation winding Np is connected in series with the switching element Q to a power supply circuit from the rectifying / smoothing circuit 12. The switching element Q is on ( ON ) / off (OFF) controlled by a switching signal Sp output from the control circuit 15 to the gate terminal.

The switching signal Sp applied from the control circuit 15 to the gate of the switching element Q is a rectangular wave having a period T as shown in FIG. 12A, which is the gate-source voltage Vgs (Q ) Waveform. A period when the switching signal Sp is at a low level is an OFF period, and a period when the switching signal Sp is at a high level is an ON period.
The inverter device 10 is a flyback type voltage resonance inverter. Therefore, the input voltage Vin is switched by the switching element Q to turn on / off the exciting current flowing through the exciting winding Np of the transformer 13. When the power is turned on, excitation energy is applied to the power winding Np. When the power is turned off, the output voltage Vout having a waveform as shown in FIG. It is applied between the electrodes of a certain discharge unit 20.

FIG. 12B shows the current between the source and drain of the switching element Q, that is, the current Id (Q) flowing through the switching element Q, which shows the waveform of the excitation current flowing through the excitation winding Np of the transformer 13. FIG. 12D shows a waveform of the output current Io flowing to the discharge unit 20.
The output voltage Vout is paralleled by the inductance Ls of the output winding Ns, the distributed capacitance Cs of the output winding Ns, and the combined capacitance C of the equivalent electrostatic capacitance (referred to as “load capacitance”) Co of the discharge unit 20 as a load. Generated by a resonant circuit.

It becomes a high voltage according to the turn ratio of the excitation winding Np and the output winding Ns. Therefore, the waveform of the output voltage Vout is a half wave shape of a substantially sinusoidal waveform as shown in FIG. 12C. In this example, the waveform is a positive (+) voltage corresponding to a positive half wave, but a negative half wave. It can also be a negative (-) voltage corresponding to a wave.
The control circuit 15 can control the output voltage Vout by changing the ratio (duty) of the ON period and the OFF period in one cycle T by controlling the switching signal Sp by pulse width modulation (PWM). The frequency and period of the switching signal Sp can be changed.

For example, as shown in FIG. 13, the discharge unit 20 includes a discharge electrode 21, a counter electrode 22 opposed to the discharge electrode 21, and a dielectric 23 interposed between the discharge electrode 21 and the counter electrode 22.
In this example, the discharge electrodes 21 are a plurality of (15 in the illustrated example) discharge electrodes 21 in the form of a round bar in which an insulator (dielectric) 21b is coated around a metal wire 21a having good conductivity such as copper or aluminum. The discharge electrode array is constituted by the above. That is, the plurality of discharge electrodes 21 are arranged in a plane parallel to the opposing surface 22a of the flat counter electrode 22 so that the outer peripheries of the electrodes adjacent to each other in the left-right direction in FIG. It is arranged extending in the direction. The diameter (φ) of each discharge electrode 21 is, for example, about 8 mm.

The counter electrode 22 is a flat electrode made of a metal having good conductivity such as copper or aluminum, and also serves as a heat sink. A dielectric 23 such as a silicon-based sheet is attached to a surface 22 a of the counter electrode 22 facing the discharge electrode 21. In FIG. 13, a gap is provided between the counter electrode 22 and the dielectric 23 for easy understanding, but in actuality, the counter electrode 22 and the dielectric 23 are in close contact by adhesion or the like.
The gap between the discharge electrode 21 and the dielectric 23 is also shown in an enlarged manner, but in actuality, a sheet-like recording material such as printing paper to be subjected to surface modification can pass as shown by an alternate long and short dash line arrow F. There should be a gap of a certain degree.

A high output voltage Vout of 6 KV or more by the inverter device 10 described above is applied between each discharge electrode 21 and the counter electrode 22 of the discharge unit 20 configured as described above. Accordingly, a dielectric barrier discharge can be generated in atmospheric pressure by creeping discharge or silent discharge, which is a kind of atmospheric plasma discharge, or by combined discharge of creeping discharge and silent discharge.
The counter electrode 22 is grounded. Even if the voltage applied to the discharge electrode 21 is reversed between positive and negative, there is no difference in the effect.

  By transporting and passing a sheet-like recording material as indicated by the dashed-dotted arrow F in the discharge unit 20, the surface thereof is activated species such as radicals and ions generated by the dielectric barrier discharge described above. The reforming proceeds by touching. It progresses due to the surface energy of the recording material being increased by the formation of various hydrophilic functional groups and other groups formed by the components in the air and the components contained in the recording material. To do. For example, when the surface of the recording material includes a portion having water repellency, the modification is performed by making the portion hydrophilic.

In order to improve the surface modification effect of the recording material as described above, the present invention continuously and uniformly activates the discharge portion without increasing the energy consumption by the system more than necessary due to heat generation of the switching element. The aim is to be able to generate seeds.
An inverter device and a plasma generator are provided for this purpose.

[First Embodiment]
A first embodiment of an inverter device and a plasma generator according to the present invention will be described with reference to FIGS.
FIG. 1 is a circuit diagram schematically showing a plasma generator using the inverter device. The plasma generator is constituted by the inverter device 1 shown in FIG. 1 and the discharge unit 2 as its load.

The inverter device 1 inputs an input voltage Vin in which a pulsating current is superimposed on a direct current or a direct current component from input terminals I1 and I2, and switches it by a switching element 4 such as an FET to excite the excitation winding of the transformer 3 Apply current. Then, an AC voltage is output from the output winding of the transformer 3, and the output voltage Vout is fed from the output terminals O1 and O2 to the discharge unit 2 as a load. A bipolar switching transistor may be used as the switching element 4.
The input voltage Vin is supplied after being rectified and smoothed by a rectifying / smoothing circuit that rectifies and smoothes an AC voltage from a commercial power supply, for example, as in the example shown in FIG.

Similarly to the control circuit 15 shown in FIG. 11, the control circuit 5 operates by the input voltage Vin, outputs the switching signal Sp to the gate terminal of the switching element 4, and turns on the switching element 4 ( ON ) / OFF (OFF). )Control. Thereby, the exciting current of the transformer 3 is intermittently switched.
11 and 12, an AC voltage is output from the output winding of the transformer 3, and power is supplied from the output terminals O <b> 1 and O <b> 2 to the discharge unit 2 that is a load.

In the discharge unit 2, for example, the discharge electrode 21 and the counter electrode 22 are opposed to each other through the dielectric 23 like the discharge unit 20 described with reference to FIG. 13, and an AC high voltage of 6 KV or more is applied by the inverter device 1. Then, dielectric barrier discharge, which is a kind of atmospheric pressure plasma discharge, is generated.
The inverter device 1 shown in FIG. 1 is different from the inverter device 10 shown in FIG. 11 in that the transformer 3 is composed of a first transformer group A and a second transformer group B having different characteristics. Is a point.

In the first embodiment, each of the first transformer group A and the second transformer group B includes one transformer T1 and T2.
The exciting windings Np1 and Np2 of the transformers T1 and T2 of the first and second transformer groups A and B are connected in parallel so that the exciting current flows simultaneously through the common switching element 4. ing.
Further, the output winding Ns1 of the transformer T1 of the first transformer group A and the output winding Ns2 of the transformer T2 of the second transformer group B are connected in parallel, and the waveform of the output voltage to the load is changed to the switching cycle. In this configuration, the output is distributed to at least two or more.

With the configuration of the transformer 3 shown in FIG. 1, the inverter device 1 can output the waveform of the output voltage to the load dispersed in at least two or more within the switching period of the excitation current. Therefore, active species can be generated continuously and efficiently in the discharge section 2 even at a relatively low switching frequency, so that heat generation of the switching element due to a high switching frequency can be suppressed.
Moreover, since it is not necessary to set the output voltage higher than necessary, the power consumption of the system can be suppressed.

FIG. 2 is a circuit diagram showing a connection relationship on the secondary side of the transformer 3 in the inverter device 1 shown in FIG.
Thus, by connecting the output winding Ns2 output winding Ns1 and transformer T2 of the transformer T1 constituting the first transformer group A and the second transformer group B of the transformer 3 in parallel, the output voltage Applied to the discharge unit 2.
In this example, the transformers T1 and T2 exhibit different characteristics due to the difference in secondary inductance, that is, the inductance of the output winding Ns1 and Ns2. In order to show this easily, in FIG. 2, the shapes of the output winding Ns1 and the output winding Ns2 are different.

If the inductance of the output winding on the secondary side of the transformer 3 is Ls , and the combined capacity of the distributed capacitance Cs on the secondary side and the load capacity Co of the discharge unit 2 is C, the resonance frequency f of the series resonant circuit is Calculated by the formula.
f = 1 / 2π√ (Ls × C)
Here, as shown in FIGS. 3 and 4, it is assumed that only the output winding Ns1 of the transformer T1 or the output winding Ns2 of the transformer T2 is connected to the discharge unit 2 of the load capacitance Co.
The resonance frequencies f1 and f2 of the respective output voltage waveforms (shown on the right side of FIGS. 3 and 4) at this time are the inductances Ls1 and Ls2 of the output windings Ns1 and Ns2 on the secondary side of the transformer T1 and transformer T2. If the relationship is Ls1> Ls2, then f1 <f2. Therefore, the periods t1 and t2 are t1> t2.

Therefore, as shown in FIG. 2, the output winding Ns1 of the transformer T1 and the output winding Ns2 of the transformer T2 are connected in parallel and connected to the discharge unit 2 of the load capacitance Co to synthesize each output voltage waveform. As a result, a composite output voltage waveform as shown in FIG. 5 is obtained.
In this case, a distorted wave is intentionally created by synthesizing the output voltage waveforms of the transformer T1 and the transformer T2.

Active species such as radicals and ions are generated by a discharge pulse, but rapidly decrease after discharge due to a time constant. In order to keep the active species uniform by repeating discharge, it is necessary to continuously generate active species by shortening the discharge pulse interval with respect to the decrease time of the active species.
However, in order to shorten the discharge pulse interval, it becomes necessary to increase the switching frequency in the inverter device. Then, problems such as heat generation of the switching element itself and heat generation of the transformer occur.

In general, the generation of active species increases in proportion to the discharge current. As a method for increasing the discharge current, it is conceivable to increase the output voltage of the inverter device. However, the output voltage is defined by system restrictions. If the output voltage exceeds the specified value, an unexpected discharge may occur in the system, which is not possible.
Therefore, as shown in FIG. 5, by intentionally generating a distorted wave, the pulse interval of the output voltage can be shortened in a pseudo manner, thereby preventing the above-described heat generation and output voltage from increasing. The active species can be continuously generated in the discharge part 2.

FIG. 6 illustrates an outline of the ON / OFF signal of the switching element, the output voltage waveform, and the amount of active species when the output windings of two transformers having the same characteristics are connected in series and the outputs are stacked. FIG.
FIG. 7 illustrates an outline of the ON / OFF signal of the switching element, the output voltage waveform, and the amount of active species when the output windings of two transformers having different characteristics are connected in parallel and the outputs are added. FIG. This corresponds to the first embodiment in which the transformer 3 of the inverter device 1 shown in FIG. 1 is configured by two transformers T1 and T2 having different characteristics.

As shown in FIGS. 6 and 7, an exciting current is supplied to the primary side of the transformer during the ON time of the switching element, and an output voltage is generated during the OFF time of the switching element. Plasma is generated by the output voltage is applied to the discharge section 2, the active species are generated.
When the peak-to-peak value of the voltage value in the output voltage waveform shown in FIG. 6 is V1pk-pk, and the peak-to-peak value of the voltage value in the output voltage waveform shown in FIG. 7 is V2pk-pk, V3pk-pk, It becomes the following relationship.
V1pk-pk>V2pk-pk> V3pk-pk

At this time, assuming that the amount of active species to be generated is N1, N2, and N3, the relationship is N1>N2> N3.
In the case of two transformers having the same characteristics shown in FIG. 6, the amount of active species generated by one discharge is large, but when the period of the switching element is long with respect to the lifetime of the active species, The amount decreases, and for example, unevenness occurs in the surface modification effect on the recording material to be conveyed.

In the case of two transformers having different characteristics shown in FIG. 7, the amount N2 of active species generated by the first discharge is smaller than the amount N1 of active species generated by two transformers having the same characteristics. However, even when the cycle of the switching element is long with respect to the lifetime of the active species, the amount of active species is not significantly reduced because the amount of active species N3 is continuously generated by the second discharge.
Therefore, there is an effect that surface modification can be continuously and uniformly performed on a recording material such as printing paper.

Here, the relationship is V1pk-pk>V2pk-pk> V3pk-pk, but the dielectric barrier discharge requires an output voltage of 6 kV or more.
Therefore, it is desirable that the waveform of the output voltage to the discharge unit 2 that is a load is distributed so that the waveform of the output voltage of 6 kV or more is at least two in the switching cycle. Thereby, dielectric barrier discharge can be reliably generated.

FIG. 8 shows the relationship between the period between the output voltage waveforms distributed by two transformers having different characteristics and the amount of active species, as shown in FIG.
As shown in FIG. 8, uniform active species can be generated continuously by setting the period between the output voltage waveforms so that the amount of active species does not become at least half or less. Thereby, unevenness of the modification effect on the recording material is suppressed. This period is, for example, several tens of μs or less.

Transformers T1 and T2 shown in FIG. 1 are resonant transformers, and assuming that the inductances of the output windings Ns1 and Ns2 are Ls1 and Ls2, respectively, the resonant frequency f1 of the output voltage waveform in the case of series resonance with the load independently. f2 is calculated by the following formula.
f1 = 1 / 2π√ (Ls1 · Ca) f2 = 1 / 2π√ (Ls2 · Cb)
Ca is a combined capacity of the distributed capacity Cs1 of the output winding Ns1 and a load capacity Co which is an equivalent capacitance of the discharge unit 2, and Cb is a combined capacity of the distributed capacity Cs2 of the output winding Ns2 and the load capacity Co. . If Cs1≈Cs2, then Ca≈Cb, and if it is the combined capacity C,
f1 = 1 / 2π√ (Ls1 · C) f2 = 1 / 2π√ (Ls2 · C)
It becomes.

Here, for example, in order to obtain the composite waveform by setting the resonance frequency f2 to twice the resonance frequency f1, the inductance Ls2 of the output winding Ns2 is set to ¼ of the inductance Ls1 of the output winding Ns1 from the above equation. Should be set to be .
Generally, the secondary inductance of the transformer (inductance of the output winding) is calculated by the following equation.
Ls = AL · ns ²

Here, ns is the number of turns of the output winding, AL is the induction coefficient of the core, μ is the permeability of the core, Ae is the effective area of the core, and L is the magnetic path length, and AL = μ · Ae / L Desired.
Therefore, in order to set the secondary side inductance of the transformer T2 to ¼ of the transformer T1, a core having an induction coefficient AL determined by the core characteristics of ¼ is selected or the number of turns of the output winding Ns2 is set. A transformer having half the number of turns of the output winding Ns1 may be manufactured.
If an attempt is made to produce a transformer with different characteristics depending on the exciting winding of the transformer or the gap characteristics of the core, the variation in heat generation between the transformers will increase.

[Second Embodiment]
Next, a second embodiment of the inverter device and the plasma generator according to the present invention will be described with reference to FIG. FIG. 9 is a circuit diagram showing a simplified plasma generator using the inverter device. Parts corresponding to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.
Each of the first transformer group A and the second transformer group B constituting the transformer of the inverter device according to the present invention may be composed of two or more transformers. Further, the number of transformers in the first transformer group A and the number of transformers in the second transformer group B may be different.

In the second embodiment shown in FIG. 9, the transformer 30 of the inverter device 1 is constituted by a first transformer group A composed of transformers T3 and T4 and a second transformer group B composed of transformers T5 and T6. .
The excitation windings Np3 to Np6 of the transformers T3 to T6 of the first and second transformer groups A and B are all connected in parallel so that the excitation current flows simultaneously via the common switching element 4. doing.

  The output windings Ns3 and Ns4 of the transformers T3 and T4 of the first transformer group A are connected in series, and the output windings Ns5 and Ns6 of the transformers T5 and T6 of the second transformer group B are also connected in series. Connected to. The output winding of the first transformer group A and the output winding of the second transformer group B, which are connected in series, are connected in parallel and connected to the output terminals O1 and O2 that supply power to the discharge unit 2. Yes.

The transformers T3 and T4 of the first transformer group A have the same characteristics (the inductances of the output windings of the transformers are the same), and the transformers T5 and T6 of the second transformer group B also have the same characteristics.
However, the first transformer group A and the second transformer group B have different characteristics. The characteristic in this case is a secondary side inductance of each of the first and second transformer groups A and B, that is, an inductance in which output windings of two transformers in each transformer group are connected in series. For this reason, in this embodiment, transformers having different characteristics are used as the transformers T3 and T4 of the first transformer group A and the transformers T5 and T6 of the second transformer group B.

Also in the inverter device of the second embodiment, as in the inverter device of the first embodiment described above, at least two waveforms of the output voltage to the discharge unit 2 that is a load are within the switching period of the excitation current. It can be dispersed and output as described above.
That is, as described above, a distorted wave is intentionally generated, and the pulse interval of the output voltage can be shortened in a pseudo manner, and thereby the discharge unit 2 can generate the heat without generating the switching element and increasing the output voltage. Active species can be generated continuously.

The transformers T3 and T4 in the first transformer group A in FIG. 9 all have the same characteristics as the transformer T1 in FIG. 1, and the transformers T5 and T6 in the second transformer group B all have the same characteristics as the transformer T2 in FIG. If there is, it becomes as follows.
The inductance LsA of the output winding of the first transformer group A is twice the inductance Ls1 of the output winding Ns1 of the transformer T1, and the inductance LsB of the output winding of the second transformer group B is the output winding of the transformer T2. This is twice the inductance Ls2 of Ns2.

Accordingly, the resonance frequency f1 on the first transformer group A side and the resonance frequency f2 on the second transformer group B side are both 1 / √2 in the case of the first embodiment, but Ls2 = Ls1 / 4. Then, LsB = LsA / 4, and f2 = 2f1.
When the input voltage Vin of the inverter device 1 is the same as that in the first embodiment, the peak value of the output voltage Vout in the second embodiment is approximately doubled.

[Third embodiment and other modifications]
Next, a third embodiment of the inverter device and the plasma generator according to the present invention will be described with reference to FIG. FIG. 10 is a circuit diagram showing a simplified plasma generator using the inverter device. Parts corresponding to those in FIGS. 1 and 9 are denoted by the same reference numerals, and description thereof is omitted.
The first transformer group A constituting the transformer 31 of the inverter device 1 shown in FIG. 10 includes two transformers T3 and T4, and the second transformer group B includes three transformers T5, T6, and T7. ing.

The excitation windings Np3 to Np7 of the transformers T3 to T7 of the first and second transformer groups A and B are all connected in parallel so that the excitation current flows simultaneously through the common switching element 4. doing.
Further, the output windings Ns3 and Ns4 of the transformers T3 and T4 of the first transformer group A are connected in series, and the output windings Ns5 and Ns6 of the transformers T5, T6 and T7 of the second transformer group B are connected. , Ns7 are also connected in series. The output winding of the first transformer group A and the output winding of the second transformer group B, which are connected in series, are connected in parallel and connected to the output terminals O1 and O2 that supply power to the discharge unit 2. Yes.

In the case of the third embodiment, the characteristics of the first transformer group A and the second transformer group B may be made different even if the characteristics of the transformers T1 to T7 used for the transformer 31 are all the same. it can.
For example, when the inductance of each output winding of each transformer T1 to T7 is Ls, the inductance LsA of the output winding (Ns3 + Ns4) of the first transformer group A is 2Ls. The inductance LsB of the output winding (Ns5 + Ns6 + Ns7) of the second transformer group B is 3Ls. Therefore, LsB = LsA · 3/2 = 1.5LsA.
Therefore, the resonance frequency f1 on the first transformer group A side and the resonance frequency f2 on the second transformer group B side can be made different.

If the first transformer group A is composed of one transformer and the second transformer group B is composed of four transformers having the same characteristics, the inductance LsA of the output winding of the first transformer group A is Ls. The inductance LsB of the output winding of the second transformer group B is 4Ls.
Therefore, although contrary to the first embodiment, the inductance LsA of the output winding of the first transformer group A is ¼ of the inductance LaB of the output winding of the second transformer group B. As a result, the resonance frequency f1 on the first transformer group A side becomes twice the resonance frequency f2 on the second transformer group B side. Therefore, the same effects as those in the first and second embodiments can be obtained.

In addition, the number of transformers constituting the first and second transformer groups A and B and the characteristics (secondary inductance) of the transformers can be variously changed. As a result, various output voltage waveforms having different resonance frequencies can be synthesized, and the waveform of the output voltage to the load can be dispersed and output in at least two or more within the switching period.
When the first and second transformer groups are each composed of one transformer, the output winding of the one transformer is used as the output winding of each transformer group. In the case of a plurality of transformers, the output windings of the transformers are connected in series to form output windings of the transformer groups. Then, the output winding of the first transformer group and the output winding of the second transformer group are connected in parallel, and the waveform of the output voltage to the load is dispersed into at least two within the switching period. Output.

Moreover, in the inverter apparatus 1 of each embodiment mentioned above, although the excitation winding of each transformer of the 1st, 2nd transformer group A and B which comprises the transformer is connected in parallel, it is limited to it. It is not a thing. Although it is indispensable to simultaneously apply excitation current to the excitation windings of all transformers, the connection form may be as follows.
・ Connect all transformer excitation windings in series.
The excitation windings of the same group of transformers are connected in parallel, and the excitation windings of the different groups of transformers connected in parallel are connected in series with each other.
The excitation windings of the same group of transformers are connected in series, and the excitation windings of the different groups of transformers connected in series are connected in parallel to each other.

The plasma generator according to the present invention can also be applied to an apparatus that generates plasma by corona discharge and an apparatus that generates plasma discharge in a low-pressure atmosphere that contains a little gas.
As mentioned above, although each embodiment of this invention has been described, the specific configuration of each part of each embodiment, the content of processing, and the like are not limited to those described therein.
Moreover, this invention is not limited to each embodiment mentioned above, It cannot be overemphasized that it is not limited at all except having the technical feature described in each claim of a claim.
Furthermore, the configuration examples, operation examples, modification examples, and the like of each embodiment described above may be changed or added as appropriate, or a part thereof may be deleted, and may be implemented in any combination as long as they do not contradict each other. Of course.

1, 10: Inverter device 2, 20: Discharge unit (load device)
3, 13, 30, 31: Transformer 4: Switching element
5, 15: Control circuit 11: Commercial power supply 12: Rectification / smoothing circuit
21: Discharge electrode 21a: Metal wire 21b: Insulator 22: Counter electrode
22a: Opposing surface 23: Dielectric 100: Plasma generator
Q: switching element A: first transformer group B: second transformer group
T1-T7: Transformer Np, Np1-Np7: Excitation winding
Ns, Ns1 to Ns7: Output windings I1, I2: Input terminals O1, O2: Output terminals
Vin: Input voltage Vout: Output voltage Co: Load capacity

JP 2009-11144 A International Publication No. 2007/060941 Pamphlet JP 2013-31338 A

Claims (8)

In an inverter device that switches an input voltage in which a pulsating current is superimposed on a direct current or a direct current component, causes an exciting current to flow in the exciting winding of the transformer, and outputs an alternating voltage from the output winding of the transformer,
Each of the transformers is composed of one or more transformers, and includes a first transformer group and a second transformer group having different characteristics due to different inductances of the output windings .
The exciting windings of the transformers of the first and second transformer groups are connected in parallel or in series so that the exciting current flows simultaneously.
When each of the first and second transformer groups is composed of one transformer, the output winding of the one transformer is used as an output winding of each transformer group. The output windings of a plurality of transformers are connected in series to form output windings of each transformer group, and the output windings of the first transformer group and the output windings of the second transformer group are connected in parallel. Then, the inverter device is characterized in that the waveform of the output voltage to the load is dispersed and output in at least two or more within the switching period.   The inverter apparatus according to claim 1, wherein excitation windings of all transformers of the first and second transformer groups are connected in parallel. 3. The inverter device according to claim 1 , wherein each transformer in a transformer group including a plurality of transformers of the first and second transformer groups has the same characteristics. 4. The inverter according to claim 1, wherein a waveform of an output voltage to the load is distributed to at least two of the waveforms having an output voltage of 6 kV or more within the switching period. 5. apparatus. An inverter device that switches an input voltage in which a pulsating current is superimposed on a direct current or a direct current component, causes an exciting current to flow in the exciting winding of the transformer, and outputs an alternating voltage from the output winding of the transformer , and the inverter device outputs wherein a discharge portion having a discharge electrode and a counter electrode an AC voltage is applied to, to generate a plasma discharge by the fact that the AC voltage is applied between the discharge electrode and the counter electrode, whereby the radical Ya A plasma generator for generating active species such as ions ,
The inverter device is
The transformer is composed of a first transformer group and a second transformer group, each composed of one or more transformers and having different characteristics.
The exciting windings of the transformers of the first and second transformer groups are connected in parallel or in series so that the exciting current flows simultaneously.
When each of the first and second transformer groups is composed of one transformer, the output winding of the one transformer is used as an output winding of each transformer group. The output windings of a plurality of transformers are connected in series to form output windings of each transformer group, and the output windings of the first transformer group and the output windings of the second transformer group are connected in parallel. Then , the plasma generating apparatus is characterized in that the waveform of the output voltage to the load is dispersed and outputted in at least two or more within the switching period . 6. The plasma generator according to claim 5, wherein the first transformer group and the second transformer group of the inverter device have inductances of the output windings different from each other. Period between the distributed output waveform in the inverter device, to claim 5 or 6 amounts of the active species in the discharge portion is characterized in that it is set to a period which is not less than half of the amount of peak The plasma generator described. Claims wherein the discharge unit has a dielectric interposed between the discharge electrode and the counter electrode, wherein said a discharge unit for generating a dielectric barrier discharge between the discharge electrode and the counter electrode Item 8. The plasma generator according to any one of Items 5 to 7 .

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