CN103747606A - Circuit generated low temperature plasma - Google Patents

Abstract

The invention discloses a low-temperature plasma generation circuit, which includes a rectifier circuit, a sinusoidal inverter circuit, a high-frequency step-up transformer and a discharge circuit; the rectifier circuit is used to convert AC voltage into DC voltage; the sinusoidal inverter circuit is used to convert DC voltage Converted into a sinusoidal AC voltage of a certain frequency; the high-frequency step-up transformer is used to boost the sinusoidal voltage; the discharge circuit is used to form a dielectric barrier corona discharge to generate low-temperature plasma; the present invention combines a suitable corona discharge with a dielectric barrier discharge , forming a dielectric barrier corona discharge that is more stable and uniform than a dielectric barrier discharge, and whose energy utilization efficiency is higher than that of a corona discharge, can be used to obtain low-temperature plasma. The disinfection box made by using the circuit of the invention solves the problems of high energy consumption, low efficiency, residue after sterilization, damage to operators and instruments, and influence on the surrounding environment in traditional sterilization methods.

Description

A low temperature plasma generating circuit

technical field

The invention belongs to the field of gas discharge and application, and more specifically relates to a low-temperature plasma generation circuit, which is especially suitable for a low-temperature plasma disinfection box.

Background technique

Disinfection and sterilization is an important part of the daily work of medical units. Statistics show that in order to prevent infection, medical staff need to perform dozens to hundreds of disinfections within a working day, with an average of about once every ten minutes. The traditional liquid sterilization method needs to be rinsed for several minutes, and frequently used Disinfectants will cause adverse skin irritation to medical staff; medical utensils are often disinfected by high temperature and high pressure or drug fumigation, which consumes a lot of energy and is cumbersome to operate. A safe, simple, fast and low-temperature disinfection method with no residual toxicity has become a need.

There are a large number of electrons, ions, atoms, molecules, active radicals and rays in low temperature plasma. Among them, active free radicals, ultraviolet rays and charged particles have a strong interaction with bacteria, forming an all-round killing environment for bacteria or viruses, with high efficiency and short time, and the gas for generating plasma can be completely non-toxic. It will not cause harm to human body and environment. Therefore, low-temperature plasma sterilization technology tends to replace traditional sterilization methods and become a new generation of sterilization technology.

Existing technologies such as Chinese patent 201220409057.3 need to generate non-thermal plasma in a vacuum device, which cannot be directly used for personnel disinfection; another example is Chinese patent 200910038771.9, which requires a sterilizing solution (such as hydrogen peroxide) to achieve the purpose of disinfection; another example Chinese patent 201010536684.9 uses pulse discharge to generate low-temperature plasma, which often requires a very high high-voltage power source for excitation, and it is difficult to insulate and safely handle it.

Promoting electrode discharge by external high-frequency AC power is a common method to generate low-temperature plasma, and its discharge forms are usually corona discharge and dielectric barrier discharge. Corona discharge is easy to realize under normal pressure, but it has poor uniformity, low electron density and energy, relatively few active substances, and it is not easy to obtain a large volume of plasma. The power density of the dielectric barrier discharge is moderate, and the low-temperature plasma generated by the discharge evenly fills the discharge gas gap, does not require vacuum equipment, and the discharge noise is small, but because the dielectric barrier discharge discharge in the air is composed of a large number of high-energy and dense discharge current filaments, Therefore, the low-temperature plasma produced by it has poor uniformity and poor stability.

Contents of the invention

In view of the above defects or improvement needs of the prior art, the present invention proposes a low-temperature plasma generation circuit, the purpose of which is to generate low-temperature plasma under normal pressure, with moderate energy density, extremely small discharge current, low noise, and no obvious Temperature rise, radiation is small.

A low-temperature plasma generation circuit provided by the present invention is characterized in that it includes a rectifier circuit, a sinusoidal inverter circuit, a high-frequency step-up transformer and a discharge circuit;

The rectifier circuit is used to convert AC voltage into DC voltage; it includes single-phase rectifier full bridge, first filter inductor, current limiting resistor, relay and DC side capacitor; the input terminal of single-phase rectifier full bridge is connected to AC power supply, single-phase The positive pole of the output terminal of the full bridge is connected to one end of the first filter inductor, the other end of the first filter inductor is connected to one end of the current limiting resistor, the relay is connected in parallel with the current limiting resistor, and the other end of the current limiting resistor is connected to one end of the DC side capacitor, The other end of the DC side capacitor is connected to the negative pole of the output end of the single-phase rectified full bridge;

The sinusoidal inverter circuit is used to convert the DC voltage into a sinusoidal AC voltage of a certain frequency; it includes the IGBT inverter full bridge, the first filter capacitor and the second filter inductor; the input end of the IGBT inverter full bridge and the two DC side capacitors The ends are connected in parallel, the anode of the output end of the IGBT inverter full bridge is connected to one end of the first filter capacitor, the other end of the first filter capacitor is connected to one end of the second filter inductor, and the other end of the second filter inductor is used to connect to the high-frequency step-up transformer ;

The high-frequency step-up transformer is used to boost the sinusoidal voltage; one end of the primary coil of the high-frequency step-up transformer is connected to the other end of the second filter inductor, and the other end is connected to the cathode of the output end of the IGBT inverter full-bridge; the iron core of the high-frequency step-up transformer is grounded , one end of the secondary winding of the high-frequency step-up transformer is connected to the discharge circuit; the other end of the secondary winding of the high-frequency step-up transformer is grounded;

The discharge circuit is used to form a dielectric barrier corona discharge to generate low-temperature plasma; it includes a second filter capacitor, a first discharge electrode and a second discharge electrode; the anode of the discharge electrode and the discharge electrode are connected to the secondary coil of the high-frequency step-up transformer One end is connected, the parallel capacitor is connected in parallel with the secondary winding of the high-frequency step-up transformer, and the discharge electrode and the cathode of the discharge electrode are grounded.

The invention combines appropriate corona discharge with dielectric barrier discharge to form dielectric barrier corona discharge that is more stable and uniform than dielectric barrier discharge, and has higher energy utilization efficiency than corona discharge, which can be used to obtain low-temperature plasma. Specifically, compared with the prior art, the above technical solution conceived by the present invention can achieve the following beneficial effects:

(1) The electrode discharge form is dielectric barrier corona discharge along the surface, which combines the advantages of corona discharge and dielectric barrier discharge. It can generate low-temperature plasma under normal pressure, with moderate energy density, extremely small discharge current, low noise and no obvious The temperature rise is small, the radiation is small, and there is no adverse effect on the operator and the surrounding environment.

(2) When the circuit of the present invention is used in a disinfection box, two groups of discharge electrodes are symmetrically placed and fixed in the cavity of the disinfection box, and low-temperature plasma is generated at the same time, and the discharge is uniform, the concentration of active particles is high, the energy utilization efficiency of the power supply is high, and the discharge area can be reduced. Adjust according to actual needs. It solves the problems of high energy consumption, low efficiency, residue after sterilization, damage to operators and equipment, and impact on the surrounding environment in traditional sterilization methods.

Description of drawings

Fig. 1 is the low-temperature plasma generation circuit diagram that the example of the present invention provides;

Fig. 2 is the structural representation of discharge electrode;

Among Fig. 1: rectification circuit 1, comprise single-phase rectification full-bridge 11, the first filtering inductance 12, current-limiting resistor 13, relay 14, DC side capacitor 15; Sinusoidal inverter circuit 2, comprise IGBT inverter full-bridge 21, the first A filter capacitor 22, a second filter inductor 23; a high-frequency step-up transformer 3; a discharge circuit 4, including a second filter capacitor 41, a first discharge electrode 42, and a second discharge electrode 43;

In FIG. 2 , wire mesh 431 , insulating material 432 , and metal foil 433 .

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

As shown in Figure 1, the low-temperature plasma generation circuit provided by the present invention includes a rectifier circuit 1, a sinusoidal inverter circuit 2, a high-frequency step-up transformer 3 and a discharge circuit 4;

The rectifier circuit 1 is used to convert the AC voltage into a DC voltage; it includes a single-phase rectification full bridge 11, a first filter inductor 12, a current limiting resistor 13, a relay 14, and a DC side capacitor 15; the input end of the single-phase rectification full bridge 11 connected to the AC power supply, the positive pole of the output end of the single-phase rectified full bridge 11 is connected to one end of the first filter inductor 12, the other end of the first filter inductor 12 is connected to one end of the current limiting resistor 13, and the relay 14 is connected in parallel with the current limiting resistor 13 to limit The other end of the flow resistor 13 is connected to one end of the DC side capacitor 15 , and the other end of the DC side capacitor 15 is connected to the negative pole of the output end of the single-phase rectified full bridge 11 .

The sinusoidal inverter circuit 2 is used to convert the DC voltage into a sinusoidal AC voltage of a certain frequency; the training includes an IGBT inverter full bridge 21, a first filter capacitor 22, and a second filter inductor 23; the input terminal of the IGBT inverter full bridge 21 is connected to the The two ends of the DC side capacitor 15 are connected in parallel, the anode of the output end of the IGBT inverter full bridge 21 is connected to one end of the first filter capacitor 22, the other end of the first filter capacitor 22 is connected to one end of the second filter inductor 23, and the second filter The other end of the inductor 23 is used to connect the high frequency step-up transformer 3 .

The high-frequency step-up transformer 3 is used to boost the sinusoidal voltage; one end of the primary side coil of the high-frequency step-up transformer 3 is connected to the other end of the second filter inductor 23, and the other end is connected to the cathode of the output end of the IGBT inverter full bridge 21. The iron core of the high-frequency step-up transformer 3 is grounded, and one end of the secondary coil of the high-frequency step-up transformer 3 is connected to the discharge circuit 4 . The other end of the 3 secondary windings of the high frequency step-up transformer is grounded.

The discharge circuit 4 is used to form a dielectric barrier corona discharge to generate low-temperature plasma. It includes a second filter capacitor 41 , a first discharge electrode 42 and a second discharge electrode 43 . The anodes of the discharge electrode 42 and the discharge electrode 43 are all connected to one end of the secondary coil of the high-frequency step-up transformer 3, the parallel capacitor 41 is connected in parallel with the secondary winding of the high-frequency step-up transformer 3, and the cathodes of the discharge electrode 42 and the discharge electrode 43 are grounded.

The rectifier circuit 1 is used to convert the input AC voltage into DC voltage. The specific working process is: the AC voltage is converted into a DC voltage by the single-phase rectified full bridge 11, filtered by the first filter inductor 12, and the DC side capacitor 15 is charged through the current limiting resistor 13, and when the DC side capacitor 15 is charged close to saturation , the relay 14 pulls in to short-circuit the current-limiting resistor 13, and after the DC-side capacitor 15 is charged stably, the output at both ends is a DC voltage with a small ripple.

The sinusoidal inverter circuit 2 is used to convert the voltage across the DC side capacitor 15 into a sinusoidal AC voltage with a certain frequency. The specific working process is: the DC voltage at both ends of the DC side capacitor 15 is converted into an AC square wave voltage with a certain frequency and amplitude through the IGBT inverter full bridge 21, and then through the first filter capacitor 22, the second filter inductor 23 and the high-frequency booster. The series resonant circuit composed of the inductance of the primary winding of the transformer 3 is filtered to obtain a high-frequency sinusoidal voltage. The frequency and amplitude of the sinusoidal voltage are set by the frequency and duty cycle of the driving signal of the IGBT inverter full bridge 21 .

The high-frequency step-up transformer 3 is used to boost the high-frequency sinusoidal voltage;

The discharge circuit 4 is used to form a dielectric barrier corona discharge to generate low-temperature plasma. The specific working process is: the parallel capacitor 41 and the secondary winding inductance of the high-frequency step-up transformer 3 form a parallel resonant circuit to filter the high-order harmonics contained in the high-frequency sinusoidal voltage, and the high-frequency sinusoidal voltage is added to the first discharge electrode 42 and the second discharge electrode 42. On the anode of the discharge electrode 43, the cathodes of the first discharge electrode 42 and the second discharge electrode 43 are grounded, and the first discharge electrode 42 and the second discharge electrode 43 are fixed symmetrically. When the frequency and amplitude of the sinusoidal AC voltage applied to the discharge electrode anode When the value satisfies the conditions, low-temperature plasma can be generated around the cathode of the discharge electrode.

The schematic diagram of the electrode structure is shown in Figure 2. The second discharge electrode 43 is composed of a metal mesh 431, an insulating material 432 and a metal foil 433 stacked in sequence. The metal foil 433 is used as the anode of the second discharge electrode 43, and the insulating material 432 is used as a barrier medium. The wire mesh 431 serves as a cathode of the second discharge electrode 43 and is grounded.

The structure and size of the first discharge electrode and the second discharge electrode are the same, and the discharge area of the electrodes can be adjusted according to actual usage conditions. The distance between the two groups of electrodes is several centimeters, the diameter of the metal wire constituting the wire mesh 431 is less than 1 mm, the thickness of the insulating material 432 and the metal foil 433 is on the order of millimeters, and the mesh size is uniformly distributed and about 5 to 10 per square centimeter .

The high-frequency AC voltage is applied to the metal foil 433, the peak value of the voltage is 5-15kV, and the frequency range is 10-15kHz. Low-temperature plasma is uniformly generated in each mesh of the wire mesh 431 . The discharge power is limited within 1W/ ^cm2 , the discharge current is extremely small, and there is no obvious temperature rise, low noise, weak radiation, and will not have adverse effects on operators, equipment and the surrounding environment.

It is easy for those skilled in the art to understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (7)

1. A low-temperature plasma generation circuit is characterized in that it comprises a rectifier circuit (1), a sinusoidal inverter circuit (2), a high-frequency step-up transformer (3) and a discharge circuit (4); The rectification circuit (1) is used to convert the AC voltage into a DC voltage; it includes a single-phase rectification full bridge (11), a first filter inductor (12), a current limiting resistor (13), a relay (14) and a DC side capacitor ( 15); the input terminal of the single-phase rectification full bridge (11) is connected to the AC power supply, the positive pole of the output terminal of the single-phase rectification full bridge (11) is connected to one end of the first filter inductor (12), and the other end of the first filter inductor (12) One end is connected to one end of the current limiting resistor (13), the relay (14) is connected in parallel with the current limiting resistor (13), the other end of the current limiting resistor (13) is connected to one end of the DC side capacitor (15), and the DC side capacitor (15 ) is connected to the negative pole of the single-phase rectification full bridge (11) output end; The sinusoidal inverter circuit (2) is used to convert the DC voltage into a sinusoidal AC voltage of a certain frequency; it includes an IGBT inverter full bridge (21), a first filter capacitor (22) and a second filter inductor (23); the IGBT inverter The input terminal of the variable full bridge (21) is connected in parallel with the two ends of the DC side capacitor (15), the anode of the output terminal of the IGBT inverter full bridge (21) is connected to one end of the first filter capacitor (22), and the first filter capacitor ( The other end of 22) is connected to one end of the second filter inductor (23), and the other end of the second filter inductor (23) is used to connect the high-frequency step-up transformer (3); The high-frequency step-up transformer (3) is used for boosting the sinusoidal voltage; one end of the primary side coil of the high-frequency step-up transformer (3) is connected to the other end of the second filter inductor (23), and the other end is connected to the IGBT inverter full bridge (21 ) the cathode of the output end; the iron core of the high-frequency step-up transformer (3) is grounded, and one end of the secondary side coil of the high-frequency step-up transformer (3) is connected to the discharge circuit (4); the other end of the secondary side winding of the high-frequency step-up transformer (3) is grounded; The discharge circuit (4) is used to form a dielectric barrier corona discharge to generate low-temperature plasma; it includes a second filter capacitor (41), a first discharge electrode (42) and a second discharge electrode (43); the discharge electrode (42) and the anode of the discharge electrode (43) are all connected with one end of the secondary coil of the high-frequency step-up transformer (3), and the parallel capacitor (41) is connected in parallel with the secondary winding of the high-frequency step-up transformer (3), and the discharge electrode (42) and the discharge electrode The cathode of (43) is grounded. 2. The low-temperature plasma generating circuit according to claim 1, characterized in that, the second discharge electrode (43) is composed of metal mesh (431), insulating material (432) and metal foil (433) in sequence, and the metal The foil (433) serves as the anode of the second discharge electrode (43), the insulating material (432) serves as the barrier medium, and the wire mesh (431) serves as the cathode of the second discharge electrode (43) and is grounded. 3. The low-temperature plasma generating circuit according to claim 1 or 2, characterized in that, the second discharge electrode (43) has the same structure and size as the first discharge electrode (42). 4. The low-temperature plasma generating circuit according to claim 2, characterized in that the thickness of the insulating material (432) and the metal foil (433) is on the order of millimeters. 5. The low-temperature plasma generation circuit according to claim 2 or 4, characterized in that, the diameter of the wire constituting the wire mesh (431) is less than 1 millimeter, and the mesh size of the wire mesh (431) is uniformly distributed and About 5 to 10 per square centimeter. 6. The low-temperature plasma generation circuit according to claim 2 or 4, characterized in that a high-frequency AC voltage is applied to the metal foil (433), the peak voltage is 5-15kV, the frequency range is 10-15kHz, and the discharge power Limit within 1W/cm2. 7. The low-temperature plasma generating circuit according to claim 2 or 4, characterized in that, the circuit is used in a disinfection box, and the second discharge electrode (43) is placed symmetrically with the first discharge electrode (42), and is fixed in the disinfection box inside the cavity.

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