CN105338723B - DBD plasma discharge device driven by high-voltage high-frequency source - Google Patents

Abstract

The invention relates to a DBD plasma discharge device driven by a high-voltage high-frequency source, which includes a high-voltage power supply, a ground electrode, a bracket, an intake pipe, a plurality of discharge tubes and a high-voltage electrode, and the high-voltage power supply includes a drive circuit, an auxiliary power supply, and a rectification circuit electrically connected in sequence , an inverter circuit and a transformer, the driving circuit is electrically connected to the inverter circuit, and the auxiliary power supply supplies power to the driving circuit. support plate, the third support plate, the air inlet pipe passes through the third support plate and the second support plate, the discharge tube includes a concentric outer quartz tube and an inner quartz tube, one end of the outer quartz tube passes through the first support plate, and enters the The gas pipe communicates with the outer quartz tube, and one end of the inner quartz tube passes through the second support plate. The high-voltage electrode includes a pole plate and a plurality of copper rods connected with the pole plate. The pole plate is connected with the output end of the transformer, and the copper rod passes through the first Three plates are inserted into the inner quartz tube. The invention has high discharge efficiency, stability and uniformity.

Description

A DBD plasma discharge device driven by a high-voltage high-frequency source

technical field

The invention relates to plasma discharge technology, in particular to a DBD plasma discharge device driven by a high-voltage high-frequency source.

Background technique

Dielectric Barrier Discharge (DBD) is a non-equilibrium gas discharge in which an insulating medium is inserted into the discharge space and a sufficient AC voltage is applied to generate plasma. Since the plasma is generated under atmospheric pressure, expensive vacuum chamber devices are omitted, and the cost of equipment is greatly reduced, so it has broad application prospects in the industrial field. At the same time, in the DBD discharge area, a large number of active substances will be produced, such as high-energy electrons, ions, free radicals and excited molecules, etc. These advantages make it suitable for industrial waste purification, environmental deodorization, material surface treatment and modification, ozone It is expected to achieve higher efficiency in applications such as production.

There are many ways to drive DBD plasma, which can be driven by DC high voltage or AC. The frequency of alternating current will also have a great influence on the discharge effect. Early AC drives used fixed low frequency (50-60Hz) variable voltage or fixed intermediate frequency (400-600Hz) variable voltage power supplies. This type of power supply is low in cost, so it is still used today, but its discharge efficiency is low. With the rapid development of the semiconductor industry, especially semiconductor switching devices, the realization of medium and high frequency (several K to hundreds of K) variable frequency discharge devices has become less difficult, and can achieve higher power, making DBD plasma driven by high frequency and high voltage The body has the possibility of large-scale application in industry.

For the application of low-temperature plasma, corona discharge and DC glow discharge are widely used in traditional processes. This method is relatively simple in technology and low in cost. However, corona discharge has a low discharge capacity, produces fewer active particles, and has low energy, so it is inefficient in applications such as treating gas, sewage, and producing ozone. Moreover, corona discharge only occurs at the tip of the needle, and cannot generate large-area uniform plasma, so it gradually fails to meet the large-area, high-power, and high-efficiency production requirements in industry. The traditional DC glow discharge also has defects. For example, in plasma heat treatment technology, the speed of suppressing arc discharge is slow and unreliable when DC power supply is used to generate glow discharge; and a current-limiting resistor is required during discharge, but the current-limiting resistor will waste a lot of electric energy and cause serious heat generation question. In addition, the hollow cathode effect often occurs in the small holes, gaps, and grooves of the workpiece, resulting in uneven surface temperature of the workpiece, making it difficult to obtain uniform plasma coverage.

In terms of the power source used, high-voltage direct current was used to drive the corona discharge in the early stage, and plasma was generated around the needle tip during the discharge, accompanied by a "hissing" sound. When the voltage continues to increase, the discharge will transform into a glow discharge. When the voltage continues to increase, the discharge space may be broken down, and there will be a strong spark discharge accompanied by a loud "pop" sound. During spark discharge, a large amount of charge flows from the high-voltage electrode to the ground electrode in an instant, and the discharge channel is thin and strong (the diameter of the discharge channel is less than 1mm), and the discharge electrode is uneven. This situation will cause damage to the discharge electrode, increase the cost of equipment operation and maintenance, and is not conducive to long-term stable work. Therefore, in the traditional process, the discharge voltage should be precisely controlled, and various methods should be adopted to prevent the generation of spark discharge.

In order to overcome the shortage of DC power drive, low-frequency AC high-voltage power was also used to drive the plasma generator in the early days. This power supply directly boosts the 220V, 50Hz power frequency AC power to a high voltage power of thousands to tens of thousands of volts at the same frequency through a step-up transformer. This driving method is simple in structure, but the obvious disadvantage is that the transformer is in a continuous working state for a long time, the volume is large, and the requirements for the step-up transformer are high. The greater the power, the higher the breakdown voltage of the electrodes, and the higher the insulation performance of the winding. The winding process is more difficult and the cost is higher; secondly, this kind of power supply is a power frequency power supply. Subsequent research shows that the rapid rising edge of the voltage will bring higher discharge efficiency, so this low-frequency AC discharge efficiency Far inferior to high-frequency alternating current.

In the late 1980s, pulsed DC glow discharge technology was developed. Due to the use of pulsed power supply, it has a faster rising edge, and its effect is obviously better than that of traditional DC and low-frequency AC power supply. It also saves energy due to its low duty cycle. But it is not conducive to the treatment of non-conductive substrates or films. On the other hand, the low-frequency DC pulse power supply is not very effective in suppressing arc discharge and hollow cathode effects. Although increasing the pulse frequency and designing an effective over-current and over-voltage protection circuit will help improve this situation, and increasing the rising edge speed of the pulse power supply (nanosecond level) will greatly improve the discharge characteristics of the plasma, but this is technically difficult. accomplish. Even now, it is difficult to simultaneously increase the frequency and rising edge speed of pulsed power supplies.

Contents of the invention

The invention overcomes the shortcomings of the prior art and provides a DBD plasma discharge device driven by a high-voltage high-frequency source.

In order to achieve the above object, the technical solution adopted in the present invention is: a DBD plasma discharge device driven by a high-voltage high-frequency source, including a high-voltage power supply, a ground electrode, a bracket, and an air intake pipe installed on the bracket, a plurality of discharge tubes and a high-voltage electrode, the high-voltage power supply includes a drive circuit, an auxiliary power supply, and a rectifier circuit, an inverter circuit, and a transformer electrically connected in sequence, the drive circuit is electrically connected to the inverter circuit, and the auxiliary power supply supplies power to the drive circuit, The bracket includes a hollow cylinder, a first support plate, a second support plate, and a third support plate which are sequentially arranged at intervals in the cylinder and are sealingly connected with the cylinder, and the air inlet pipe passes through the third support plate. plate, the second support plate, the discharge tube includes a concentric outer quartz tube and an inner quartz tube, one end of the outer quartz tube passes through the first support plate, the air inlet tube and the outer quartz tube One end of the inner quartz tube passes through the second support plate, the high-voltage electrode includes a pole plate, a plurality of copper rods connected to the pole plate, and the pole plate is connected to the output end of the transformer connected, the copper rod is inserted into the inner quartz tube through the third support plate.

In a preferred embodiment of the present invention, a DBD plasma discharge device driven by a high voltage and high frequency source further includes that the inverter circuit is a class E inverter circuit.

In a preferred embodiment of the present invention, a DBD plasma discharge device driven by a high-voltage high-frequency source further includes that the output voltage of the auxiliary power supply is 15V.

In a preferred embodiment of the present invention, a DBD plasma discharge device driven by a high-voltage high-frequency source further includes that the magnetic core of the transformer is a UY30 ferrite high-frequency magnetic core.

In a preferred embodiment of the present invention, a DBD plasma discharge device driven by a high-voltage high-frequency source further includes that the ratio of the number of turns of the primary coil to the number of turns of the secondary coil is 1:40-1:50.

In a preferred embodiment of the present invention, a DBD plasma discharge device driven by a high-voltage high-frequency source further includes a plurality of said discharge tubes in an annular array.

In a preferred embodiment of the present invention, a DBD plasma discharge device driven by a high-voltage high-frequency source further includes a gap of 1-2 mm between the inner wall of the outer quartz tube and the outer wall of the inner quartz tube.

The present invention has the following beneficial effects:

(1) The dielectric barrier discharge (DBD) technology is selected for the discharge mode. Compared with glow discharge, DBD has a larger discharge capacity and higher discharge efficiency, and can generate large-area uniform plasma, which is conducive to high-power and large-scale industrial applications. area application.

(2) There is a medium inserted into the discharge space, which can effectively suppress the spark discharge, so that the discharge voltage can be adjusted in a wide range, and effectively protect the discharge electrodes, so that the discharge device can run stably for a long time.

(3) High-voltage and high-frequency AC drive is used on the driving power supply, which can not only ensure the efficiency and uniformity of plasma generation, but also is simpler than the nanosecond pulse voltage process, and is relatively easy to implement, which is conducive to reducing production costs in the industry.

(4) The power supply is completely self-developed and can be well matched with the discharge device.

(5) The structure of the power supply is simple and reliable, the generated waveform is stable, and the cost is low. The components are all high-power and high-voltage withstand devices in the industry. The design of each device has a margin of 3-5 times, so that the power supply works stably and is not easy Breakdown, burning and other quality problems occur.

(6) The entire system adopts a modular design, which is easy to install and operate, and is conducive to later maintenance, repair, testing, cleaning, replacement, etc., to meet the needs of large-scale industrial applications.

Description of drawings

The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

Fig. 1 is the circuit principle block diagram of the high-voltage power supply of preferred embodiment of the present invention;

Fig. 2 is the circuit diagram of the high voltage power supply of the preferred embodiment of the present invention;

Fig. 3 is the voltage of the high-voltage power supply of the preferred embodiment of the present invention, current waveform diagram;

Fig. 4 is a schematic structural view of a plurality of discharge tubes installed on a bracket in a preferred embodiment of the present invention;

Figure 5 is a cross-sectional view of a preferred embodiment of the present invention;

Fig. 6 is a schematic cross-sectional view of a discharge tube connected to a copper rod in a preferred embodiment of the present invention;

Fig. 7 is a discharge effect diagram of a preferred embodiment of the present invention.

Detailed ways

The present invention will now be further described in detail in conjunction with the accompanying drawings and embodiments. These drawings are all simplified schematic diagrams, only illustrating the basic structure of the present invention in a schematic manner, so it only shows the composition related to the present invention.

As shown in Figure 1, Figure 4-Figure 6, a DBD plasma discharge device driven by a high-voltage high-frequency source, including a high-voltage power supply, a ground electrode 2, a bracket, and an air intake pipe 4 installed on the bracket, a plurality of discharge tubes 6 and a high-voltage The electrode, the high-voltage power supply includes a drive circuit 10, an auxiliary power supply 12, and a rectifier circuit 14, an inverter circuit 16, and a transformer 18 that are electrically connected in turn, the drive circuit 10 is electrically connected to the inverter circuit 16, and the auxiliary power supply 12 supplies power to the drive circuit 10. It includes a hollow cylinder 20, a first support plate 22, a second support plate 24, and a third support plate 26 which are sequentially arranged in the cylinder body 20 and are sealingly connected with the cylinder body 20. The air intake pipe 4 passes through the third support plate 26. The second support plate 24, the discharge tube 6 includes a concentric outer quartz tube 28 and an inner quartz tube 30, one end of the outer quartz tube 28 passes through the first support plate 22, and the air inlet pipe 4 communicates with the outer quartz tube 28, One end of the inner quartz tube 30 passes through the second support plate 24, and the high-voltage electrode includes a pole plate 32, a plurality of copper rods 34 connected with the pole plate 32, the pole plate 32 is connected with the output end of the transformer 18, and the copper rods 34 pass through The third support plate 26 is inserted into the inner quartz tube 30 .

As shown in Figure 2, the 220V, 50Hz single-phase AC mains is connected to the rectifier circuit 14, and the rectifier circuit 14 first converts the AC signal waveform into a half-period sinusoidal signal through the bridge rectifier diode D1, which is already DC Signal but the voltage value fluctuates greatly, and then remove the high-frequency part of the waveform through the filter capacitor C4 to reduce the fluctuation of the signal, and finally output a stable DC signal through the Zener diode D2, the output voltage is adjustable from 0-60V, and the maximum output current is 12A , The maximum output power is 720W, which can provide a large current and withstand a large voltage impact during operation to meet the needs of subsequent circuits. The principle of the auxiliary power supply 12 is similar to that of the rectifier circuit 14, but it does not need to output a large power. Therefore, the preferred output voltage of the auxiliary power supply 12 in the present invention is 15V for powering the drive circuit 10 and other active devices. The preferred inverter circuit 16 of the present invention is an E-type inverter circuit. The switching device of the inverter circuit 14 is a single-tube IGBT with a rated voltage of 1000V and a rated current of 60A. The DC input charges the subsequent inductor and capacitor network through the inductor L1. When it is turned on, the L and C networks release excess electric energy through the IGBT. Through such repeated charging and discharging, an AC voltage can be generated on the capacitor C3 to drive the load. The drive circuit 10 adopts the EXB841 integrated drive chip of Fuji Corporation of Japan. This chip has the advantages of high isolation strength, fast response speed, etc., and can implement over-current protection for IGBT. The square wave signal generated by the chip and its expansion circuit can be quickly Effectively control the on and off of the IGBT to realize the charging and discharging of the inverter circuit 16, and generate an alternating current with a maximum amplitude of about 800V and a frequency of about 25KHz.

The magnetic core of the preferred transformer 18 of the present invention is a UY30 ferrite high-frequency magnetic core, its relative magnetic permeability is 2000-2600, the magnetic circuit length is 300-360mm, the effective cross-sectional area of the magnetic core is 650-750mm ² , and the cut-off frequency is 90-110K, the skeleton of the transformer 18 is made of polytetrafluoroethylene, and the ratio of the number of turns of the primary coil to the number of turns of the secondary coil is 1:40-1:50. Further preferably, the relative magnetic permeability of the transformer 18 is 2300, the magnetic circuit length is 330.8mm, the effective cross-sectional area of the magnetic core is 691.9mm ² , the cut-off frequency is 100K, the number of turns of the primary coil is 10, and the number of turns of the secondary coil is 450 (per Layer 90 circles, a total of 5 layers). Due to the high voltage, it is necessary to take good insulation measures. The high-voltage and high-temperature-resistant gold finger tape is used for winding insulation between each layer of the coil. The gold finger tape is polyimide tape, and the thickness of a single layer is only 0.1mm. up to several thousand volts. In addition, measures to apply ceramic glue for insulation can be taken for parts that are prone to breakdown discharge.

Finally, the secondary coil of the transformer 18 outputs high-voltage alternating current with an adjustable voltage amplitude of 0-30kV and a frequency of 25KHz. In addition, a cooling device is installed on the device that is prone to heat, such as the inverter circuit 16 , to ensure stable and reliable operation of the device. The cooling device is powered by the auxiliary power supply 12 . The high-voltage power supply adopts a modular design, which makes the installation, operation, testing and maintenance of the power supply very convenient. Figure 3 shows the voltage and current waveforms measured when the high-voltage power supply drives the plasma discharge device, where the voltage waveform is displayed by curve ①, and the current waveform is displayed by curve ②.

A copper wire is wound on the outside of the outer quartz tube 28 and grounded as the ground electrode 2 . In the present invention, a plurality of discharge tubes 6 are preferably in an annular array. Both ends of the outer quartz tube 28 are open, one end of the inner quartz tube 30 inside the outer quartz tube 28 is closed, and the other end extending outside the outer quartz tube 28 is open. The connection between the outer quartz tube 28 and the first support plate 22 is sealed, the connection between the inner quartz tube 30 and the second support plate 24 is sealed, and the connection between the air inlet pipe 4 and the third support plate 26 and the second support plate 24 is sealed. , to ensure that the exhaust gas enters the outer quartz tube 28 along the intake pipe 6 . The gap between the inner wall of the outer quartz tube 28 and the outer wall of the inner quartz tube 30 is 1-2mm, and this gap is the reaction zone for generating plasma discharge. When in use, the waste gas to be treated is passed into the reaction area of each discharge tube 6 through the intake pipe 4, and plasma is generated and reacted under the drive of high-voltage alternating current. The discharge effect is shown in Figure 7, and the discharge efficiency is high and the discharge is stable and uniform. , the treated clean gas is discharged from the end of the outer quartz tube 28.

The above is inspired by the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications within the scope of not departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the content in the specification, and must be determined according to the scope of the claims.

Claims (5)

1. A kind of 1. DBD plasma discharge apparatus of high voltagehigh frequency source driving, it is characterised in that：Including high voltage power supply, ground electrode, Air inlet pipe, multiple discharge tubes and the high-field electrode of support and installation on the bracket, the high voltage power supply include driving electricity Road, accessory power supply and the rectification circuit being sequentially connected electrically, inverter circuit and transformer, the drive circuit and inversion electricity Road electrically connects, and the accessory power supply gives the drive circuitry, and the inverter circuit is E class inverter circuits, the inversion electricity The switching device on road selects rated voltage 1000V, rated current 60A single tube IGBT, the magnetic conductivity of the magnetic core of the transformer For 2000-2600, length of magnetic path 300-360mm, magnetic core net sectional area be 650-750mm2, cut-off frequency 90-110K, The ratio between the number of primary turns of the transformer and secondary winding turns are 1：40-1:50, the support include hollow cylinder, The first support plate, the second support plate, the 3rd support plate that interval is tightly connected in the cylinder and with cylinder successively, the air inlet pipe Through the 3rd support plate, the second support plate, the discharge tube includes the outer quartz ampoule of concentric-ring pattern and interior quartz ampoule, the outer stone One end of English pipe passes through first support plate, and the air inlet pipe is connected with the outer quartz ampoule, and one end of the interior quartz ampoule is worn Cross second support plate, multiple copper rods that the high-field electrode includes pole plate, is connected with the pole plate, the pole plate and the change The output end of depressor is connected, and the copper rod is inserted in the interior quartz ampoule through the 3rd support plate.
2. A kind of 2. DBD plasma discharge apparatus of high voltagehigh frequency source driving according to claim 1, it is characterised in that： The output voltage of the accessory power supply is 15V.
3. A kind of 3. DBD plasma discharge apparatus of high voltagehigh frequency source driving according to claim 1, it is characterised in that： The magnetic core of the transformer is UY30 ferrite high frequency magnetic cores.
4. A kind of 4. DBD plasma discharge apparatus of high voltagehigh frequency source driving according to claim 1, it is characterised in that： Multiple discharge tube circular arrays.
5. A kind of 5. DBD plasma discharge apparatus of high voltagehigh frequency source driving according to claim 1, it is characterised in that： Gap between the inwall of the outer quartz ampoule and the outer wall of interior quartz ampoule is 1-2mm.