JPH0959006A - Power source for ozone generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the discharge efficiency in O3 generation process and reduce the generation cost by using a three-phase current inverter as a power source for applying a high-frequency high-voltage, transforming the output voltage of the inverter with a specific transforming means and supplying the transformed power between high-voltage electrodes and earthed electrodes of plural discharge tubes. SOLUTION: A plurality of discharge tubes each having a dielectric tube composed of a high-voltage electrode formed on the inner circumference of a tubular dielectric material and an earthed electrode tube placed around the dielectric tube interposing a gap from the outer circumference of the dielectric tube are arranged parallel to each other. A high-frequency high-voltage is applied between the high-voltage electrode and the earthed electrode of each discharge tube to generate O3 in a raw material gas flowing through the gap. In a silent discharge-type O3 generator having the above mechanism, a three-phase current inverter 11 composed of a rectifier part 12, a DC reactor 13 and an inverter part 14 is used as the power source, the output voltage of the inverter 11 is transformed by a booster transformer 15 having delta-ster connection and the output voltage of each phase is applied to each of sections obtained by dividing the plural discharge tubes into three sections.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device used in a medium to large capacity ozone generator.

[0002]

2. Description of the Related Art Inverters are often used as power sources for ozone generators that use silent discharge. By the high voltage of a frequency of about 1 kH _Z inverter is applied to the ozone generating tube, since the discharge power density it is possible to increase 2 to 3 times that of the commercial frequency, is possible to reduce the size of the device it can. Further, since the peak voltage applied to the ozone generating tube can be lowered, the stress on the generating tube (= glass tube) is reduced and the life can be extended.

An inverter for ozone generation is usually shown in FIG.
A single-phase current source inverter such as is used. In FIG. 3, a single-phase current source inverter 1 includes a forward converter 2 for converting AC power into DC, a DC reactor 3 connected to a DC intermediate circuit, and an inverse converter 4 for converting DC power into AC.
It is composed of

Reference numeral 5 is a step-up transformer for stepping up the output voltage of the inverter 1. Reference numerals 6a to 6n are a plurality of discharge tubes that constitute an ozone generator. These discharge tubes 6a to 6n
Is a cylindrical dielectric, for example, a glass tube (dielectric tube) 7a to 7n in which a high voltage electrode is provided on the inner peripheral surface of glass, and is provided on the outer circumference of the glass tube 7a to 7n with a gap therebetween. SU
S tubes (ground electrode tubes) 8a to 8n.

One end of the secondary winding of the step-up transformer 5 is connected to high voltage electrodes provided on the inner peripheral surfaces of the glass tubes 7a to 7n, and the other end is connected to the SUS tube. The output voltage of the single-phase current source inverter 1 is stepped up by the step-up transformer 5 and supplied to the plurality of discharge tubes.

As described above, the reason why the single-phase current source inverter is used as the power source of the ozone generator is that the glass tube having the high-voltage electrode formed inside and the glass tube
This is because electricity is supplied between the ground electrode and the ground electrode, which are opposed to each other with a gap of 1.5 mm. The reason why the inverter is a current type is that it can be operated with the highest power factor from the equivalent circuit of ozone generation (reference document: Tabata, Yagi: Denki B, 95, 5, 249 (Showa 50-5)). .

[0007]

As described above, the current source inverter has a merit that the load power factor is good, but the data of the reference documents show that the power factor is about 0.5 at most. The fact that the load power factor is 0.5 means that the inverter supplies the same amount of extra current in addition to the current used for the discharge power that actually contributes to ozone generation (in terms of phase relationship). The magnitude of the combined current is √2 times). Therefore, there is a problem that the utilization rate of the inverter capacity is poor.

The present invention has been made in view of the above points, and an object thereof is to provide a power supply device for an ozone generator, which has improved load power factor and discharge efficiency for ozone generation.

[0009]

[Means for Solving the Problems]

(1) In order to solve the above problems, in the present invention, a dielectric tube having a high-voltage electrode provided on the inner peripheral surface of a cylindrical dielectric body, and a dielectric tube provided on the outer periphery of the dielectric tube with a gap therebetween. A plurality of discharge tubes having a ground electrode tube are arranged side by side, a high frequency high voltage is applied between the high voltage electrode of each discharge tube and the ground electrode tube, and in the raw material gas circulated in the cavity. In a silent discharge type ozone generator for generating ozone, a three-phase current source inverter is used as a power source for applying the high frequency high voltage, and the output voltage of the inverter is transformed by a predetermined transformer to transform the plurality of high voltage discharge tubes. It is characterized in that it is configured to supply between the electrode and the ground electrode, characterized in that the predetermined transforming means transforms by a transformer of delta star connection, wherein the transformer of delta star connection The neutral point of the multiple Connected to the ground electrodes of the tube, the first phase of the star winding, the total number of said plurality of discharge tubes 1/3
, Which are connected to the high voltage electrodes of the first group of discharge tubes, and the second phase of the star winding accounts for 1/3 of the total number of the plurality of discharge tubes. And a third phase of the star winding is connected to a high-voltage electrode of a third group of discharge tubes, which accounts for ⅓ of the total number of the plurality of discharge tubes. The high-voltage electrodes provided on the inner peripheral surface of the body are divided into three parts, which are arranged at predetermined intervals to form a dielectric tube, and the neutral point of the transformer in the delta star connection is grounded to the plurality of discharge tubes. And connecting a first phase of the star winding to a first high voltage electrode of the three divided high voltage electrodes of the plurality of discharge tubes, and connecting a second phase of the star winding to the first high voltage electrode. Of the three divided high voltage electrodes of the plurality of discharge tubes, each is connected to a second high voltage electrode, and the third phase of the star winding is connected to the front side. It is characterized in that respectively connected to the third high-voltage electrode of the three divided high voltage electrode of the plurality of discharge tubes.

(2) Since the ozone generator can be driven by using the three-phase current source inverter as the power source, the sum of the reactive power generated in each of the three phases becomes zero, and the load power factor becomes very good. Further, since it is a three-phase drive, the discharge is made uniform over time, and the discharge efficiency of ozone generation is improved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows an embodiment of the present invention. Reference numeral 11 denotes a forward conversion unit 1 for converting AC power into DC.
2 and a DC reactor 13 connected to the DC intermediate circuit
And a reverse converter 14 for converting DC power into AC, which is a three-phase current source inverter. The AC output side of the three-phase current source inverter 11 is connected to the delta windings of the step-up transformer 15 having a delta star connection.

Each end (a, b, c phase) of the three phases of the star winding of the step-up transformer 15 is 1/3 of the total number of the discharge tubes (6a to 6n) of the ozone generator. It is connected to each high-voltage electrode of the discharge tubes of the number (not shown).
The neutral point of the star winding of the step-up transformer 15 is connected to the ground electrode of the discharge tube, that is, the SUS tube (8a to 8n) (not shown). The inverse conversion unit 14 is formed by connecting, for example, a transistor and a diode in series in a three-phase bridge connection.

In the device constructed as described above, 3
The output voltage of the phase current source inverter 11 is the step-up transformer 15
It is boosted by and is supplied to each discharge tube. At this time, the sum of the instantaneous values of the reactive power generated in each of the three phases becomes zero. Therefore, in order to suppress harmonics caused by the switching operation of the transistor of the inverse conversion unit 14, the DC reactor 1
Although 3 cannot be completely eliminated, its inductance value can be extremely small. Therefore, the size of the inverter can be reduced and the cost can be reduced, and the load power factor can be greatly improved.

[0014]

EXAMPLE In the present invention, as shown in FIG. 2, the high voltage electrodes 21a to 21a provided on the inner peripheral surface of the dielectric of each of the discharge tubes are provided.
1n, 22a-22n, 23a-23n, etc.
It may be divided and arranged at predetermined intervals. That is, in this embodiment, the device X having the three-phase current source inverter 11 and the step-up transformer 15 shown in FIG. 1 is used, and the neutral point of the star winding of the step-up transformer 15 is connected to the ground electrode of the discharge tube ( (Not shown), the a phase of the star winding is connected to the high voltage electrodes 21a to 21n of the plurality of discharge tubes, and the b phase is connected to the high voltage electrodes 22a to 22n of the plurality of discharge tubes.
And the c phase is connected to each of the high voltage electrodes 23 of the plurality of discharge tubes.
a to 23n, respectively.

In the apparatus constructed as described above, when the apparatus is in operation, the sum of the instantaneous values of the reactive power generated in each of the three phases becomes zero, as in the case of FIG. Therefore, although the DC reactor 13 cannot be completely eliminated in order to suppress harmonics caused by the switching operation of the transistor of the inverse conversion unit 14, its inductance value can be extremely small. Therefore, the size of the inverter can be reduced and the cost can be reduced, and the load power factor can be greatly improved.

[0016]

As described above, according to the present invention, in a silent discharge type ozone generator, a three-phase current source inverter is used as a power source for applying a high frequency high voltage, and the output voltage of the inverter is delta star connection. Of the plurality of discharge tubes, and the number of the plurality of discharge tubes is changed to 3 between the high voltage electrode and the ground electrode of the plurality of discharge tubes.
Since the high voltage electrodes are divided or the high voltage electrodes are divided into three parts and the output voltages of the three phases of the transformer are applied to them, the following excellent effects can be obtained.

(1) The reactive power that deteriorates the load power factor is electric power that does not contribute to discharge between the power source and the load in terms of an electric circuit, and the energy is taken in and out in the current source inverter on the DC side. The DC reactor that is inserted into is doing. However, it has been clarified that the sum of the instantaneous values of the reactive power generated in each phase becomes zero in the three-phase circuit. In other words, the DC reactor is ideally unnecessary.

In practice, the inverter converts DC power into AC power by the switching action of the semiconductor element,
Although it is not possible to completely eliminate the DC reactor on the generation of harmonics and on the forward conversion side for the same reason, the size of the inductance is about 1/2 to 1/4 that of the conventional one, and the size of the inverter is small. And cost reduction.

(2) There is also an advantage that the discharge efficiency of ozone generation is improved. This is considered to be because the discharge was made uniform over time by driving in three phases. Ozone yield is several% compared to the case of driving with a conventional single-phase inverter
It was clarified as a result of the experiment that the degree of improvement is high.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing another embodiment of the present invention.

FIG. 3 is a circuit diagram showing an example of a conventional power supply device for an ozone generator.

[Explanation of Codes] 1 ... Single-phase current source inverter 6a-6n ... Discharge tube 7a-7n ... Glass tube 8a-8n ... SUS tube 11 ... Three-phase current source inverter 12 ... Forward converter 13 ... DC reactor 14 ... Reverse conversion Part 15 ... Step-up transformer 21a-21n, 22a-22n, 23a-23n ... High-voltage electrode

Claims (4)

[Claims] 1. A discharge having a dielectric tube in which a high-voltage electrode is provided on the inner peripheral surface of a cylindrical dielectric, and a ground electrode tube disposed on the outer periphery of the dielectric tube with a gap therebetween. A plurality of tubes are arranged in parallel, a high-frequency high voltage is applied between the high-voltage electrode and the ground electrode tube of each discharge tube, and a silent discharge type ozone that generates ozone in the raw material gas circulated in the cavity In the generator, a three-phase current source inverter is used as a power source for applying the high frequency high voltage, and the output voltage of the inverter is transformed by a predetermined transformer to be supplied between the high voltage electrode and the ground electrode of the plurality of discharge tubes. A power supply device for an ozone generator, which is configured as described above. 2. The power supply device for an ozone generator according to claim 1, wherein the predetermined transformer is a transformer having a delta star connection. 3. The neutral point of the transformer of the delta star connection is connected to the ground electrodes of the plurality of discharge tubes, and the first phase of the star winding is connected to the total number of the plurality of discharge tubes. 1/3
, Which are connected to the high voltage electrodes of the first group of discharge tubes, and the second phase of the star winding accounts for 1/3 of the total number of the plurality of discharge tubes. 7. The third phase of the star winding is connected to each of the high voltage electrodes of the third group of discharge tubes, which accounts for 1/3 of the total number of the plurality of discharge tubes. 2. A power supply device for an ozone generator according to 2. 4. A high voltage electrode provided on the inner peripheral surface of the dielectric is divided into three parts, respectively, which are arranged at predetermined intervals to form a dielectric tube, and a neutral point of the transformer of the delta star connection is formed. The star winding is connected to ground electrodes of the plurality of discharge tubes, and the first phase of the star winding is connected to first high voltage electrodes of the three divided high voltage electrodes of the plurality of discharge tubes. Second
Of the three divided high voltage electrodes of the plurality of discharge tubes are respectively connected to a second high voltage electrode, and the third phase of the star winding is divided into three divided high voltage electrodes of the plurality of discharge tubes. The third high voltage electrode is connected to the third high voltage electrode, respectively.
The power supply device for an ozone generator according to.