Spray gun abnormal arc discharge detection circuit for atmospheric plasma power supply

Abstract

The utility model relates to a spray gun abnormal arc discharge detection circuit for an atmospheric plasma power supply, which belongs to the technical field of power electronics and comprises a voltage detection module, a current detection module, a power judgment module and a delay unit. Power frequency power grid voltage is subjected to full-bridge rectification of a rectifier bridge and smoothing of a filter capacitor to generate approximate direct-current voltage, and voltage sampling is carried out on the approximate direct-current voltage through a voltage detection module; the current detection module samples the current sent to the inverter bridge after passing through the filter capacitor; the power judgment module calculates the current power supply power by integrating the sampled voltage and current, compares the current power supply power with a set value, and judges the arc state of a spray gun of the current atmospheric plasma power supply; and the detection sensitivity is adjusted through certain delay setting. By using the provided detection circuit, the arc state of the spray gun of the atmospheric plasma power supply can be effectively detected at low cost, industrial production safety accidents caused by abnormal arc discharge of the spray gun are avoided, and the safety of the atmospheric plasma power supply is improved.

Description

Technical Field

[0001] The utility model relates to the field of detection technology, in particular to an abnormal arc detection circuit for a spray gun of an atmospheric plasma power supply. Background Art

[0002] Atmospheric plasma technology is widely used in industrial production activities for cleaning and modifying material surfaces, such as cleaning foreign matter before PCB plating, cleaning edge gaps during the assembly of mobile phones and other electronic products, and modifying the surface of cable coding to improve activity. The atmospheric plasma power supply uses a bridge inverter boost, and the alternating high-voltage electric field is loaded on the spray gun electrode. The air passing through the high-voltage electric field is quickly ionized to form a plasma, and leaves the electric field under the push of subsequent compressed air. The highly active plasma acts on the working area, producing the effect of cleaning and modifying the material surface. Since the alternating high-voltage electric field voltage is as high as 10KV, the atmospheric plasma power supply and the spray gun are usually connected with a high-voltage cable. One of the high-voltage cables needs to be safely grounded, and the high-voltage cable is securely fixed and cannot be moved at will. As the working time of the spray gun goes by, the electrode will be ablated, the distance between the electrodes will gradually increase, and the voltage of the electric field breaking through the air to generate plasma will gradually increase. When the breakdown voltage is greater than the cable withstand voltage, the arc will not be generated from the electrode of the spray gun, but from somewhere in the cable. The plasma generated on the cable will show obvious ablation and even ignite other surrounding combustibles with open flames, causing production safety accidents. Therefore, it is very necessary to detect abnormal arcing during spray inspection. Although the arc state of the spray gun can be determined by directly detecting the voltage of the spray gun, the high-voltage detection module usually has a high cost. The arc state of the spray gun is directly related to the power supply power. When the spray gun abnormally arcs, the power supply power will be significantly reduced. Therefore, the arc state of the spray gun can be determined by detecting the power consumption of the power supply. Utility Model Content

[0003] The utility model proposes a method to solve the problems of high cost mentioned in the prior art.

[0004] In order to achieve the above purpose, the utility model provides the following technical solutions:

[0005] A spray gun abnormal arcing detection circuit for an atmospheric plasma power supply comprises a voltage detection module, a current detection module, a power judgment module, a delay unit, a full-bridge rectifier filter module, a bridge inverter boost module and a plasma spray gun, wherein the input end of the full-bridge rectifier filter module is connected to the power frequency voltage, the output end of the full-bridge rectifier filter module is respectively connected to the bridge inverter boost module, the voltage detection module and the current detection module, the bridge inverter boost module is also connected to the plasma spray gun, the voltage detection module and the current detection module are simultaneously connected to the power judgment module, the power judgment module is connected to the delay unit, and the delay unit is connected to the bridge inverter boost module.

[0006] As a further technical solution of the utility model: the full-bridge rectifier and filter module includes a rectifier BD1, a capacitor C1, a resistor R1 and a resistor R2, the two input ends of the rectifier BD1 are respectively connected to the AC neutral line and the live line, an output end of the rectifier BD1 is connected to the capacitor C1, the resistor R1 and the bridge inverter boost module, the other end of the resistor R1 is connected to the resistor R2 and the voltage detection module, and the other end of the capacitor C1 is connected to the other end of the resistor R2, the other output end of the rectifier BD1 and the ground end.

[0007] As a further technical solution of the utility model: the voltage detection module includes a linear optocoupler U2A, a resistor R1A, a resistor R2A, a resistor R3A, a resistor R4A, a resistor R5A, an amplifier OP1 and a capacitor C1A, one end of the resistor R1A is connected to the linear optocoupler U2A, the other end of the resistor R1A is connected to the resistor R3A and the positive input end of the amplifier OP1, the inverting input end of the amplifier OP1 is connected to the resistor R2A and the resistor R4A, the other end of the resistor R4A is connected to the output end of the amplifier OP1 and the resistor R5A, the other end of the resistor R5A is connected to the capacitor C1A and the MCU, and the other end of the capacitor C1A is grounded.

[0008] As a further technical solution of the utility model: the current detection module includes a linear optocoupler U2B, a resistor R1B, a resistor R2B, a resistor R3B, a resistor R4B, a resistor R5B, an amplifier OP2 and a capacitor C1B, one end of the resistor R1B is connected to the linear optocoupler U2B, the other end of the resistor R1B is connected to the resistor R3B and the positive input end of the amplifier OP2, the inverting input end of the amplifier OP2 is connected to the resistor R2B and the resistor R4B, the other end of the resistor R4B is connected to the output end of the amplifier OP2 and the resistor R5B, the other end of the resistor R5B is connected to the capacitor C1B and the MCU, and the other end of the capacitor C1B is grounded.

[0009] As a further technical solution of the utility model: the power judgment module and the delay unit are implemented by an 8-bit microcontroller MCU.

[0010] In the above technical solution, the technical effects and advantages provided by the utility model are:

[0011] There is no need to directly detect the high voltage electric field on the electrode of the plasma spray gun. The arc state of the spray gun can be judged by detecting the power of the atmospheric plasma power supply, which effectively achieves the detection purpose and has a low cost.

[0012] By adjusting the delay unit length T delay , the sensitivity of the spray gun arc state detection can be flexibly modified to take into account the anti-interference and rapidity of the detection circuit. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0014] Figure 1 This is a block diagram of the abnormal arc detection circuit for a plasma spray gun proposed by the utility model;

[0015] Figure 2 This is a circuit diagram for detecting abnormal arcing of a plasma spray gun proposed by the utility model;

[0016] Figure 3 The utility model provides a detection flow chart of an abnormal arcing detection circuit of a plasma spray gun. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the utility model to clearly and completely describe the technical solutions in the embodiments of the utility model. Obviously, the described embodiments are only part of the embodiments of the utility model, not all of the embodiments. Based on the embodiments in the utility model, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the utility model.

[0018] Example 1

[0019] The utility model provides Figure 1 The drawings shown are specifically a spray gun abnormal arcing detection circuit for atmospheric plasma power supply, including full-bridge rectification filtering and bridge inverter boost, the voltage detection module and the current detection module are connected to the power judgment module at the same time, the power judgment module is connected to the delay unit, the delay unit is connected to the bridge inverter boost, the power frequency grid voltage is rectified by the full-bridge rectifier bridge and smoothed by the filter capacitor to generate an approximate DC voltage, which is sampled by the voltage detection module; secondly, the current detection module samples the current flow sent from the filter capacitor to the inverter bridge; thirdly, the power judgment module calculates the current power supply power by comprehensively sampling the voltage and current, compares it with the power threshold, and determines the spray gun arc state of the current atmospheric plasma power supply; finally, after a certain delay setting, the detection sensitivity is adjusted, and the spray gun arc state detection result is finally determined. After the delay unit, the spray gun arc state detection result is finally determined. When the result is determined to be abnormal spray gun arcing, the command to shut down the atmospheric plasma power supply is executed, that is, the bridge inverter boost is shut down.

[0020] Example 2

[0021] On the basis of Example 1, the voltage detection module adopts an optocoupler isolation sampling circuit to connect the full-bridge rectifier filter high voltage and the power judgment module low voltage.

[0022] The current detection module adopts an optocoupler isolation sampling circuit. The average current from the full-bridge rectifier filter to the bridge inverter boost transmission is converted into a low voltage signal and sent to the power judgment module.

[0023] The power judgment module and delay unit are implemented using a low-cost 8-bit microcontroller MCU.

[0024] Here’s how it works:

[0025] (1): Use the voltage detection module to sample the DC voltage after rectification and filtering of the power frequency grid voltage to obtain the DC voltage U dc , circuit such as Figure 2 As shown in , it is composed of resistors R1A-R5A, capacitor C1A, linear optocoupler U2A and op amp OP1;

[0026] (2): Use the current detection module to sample the current sent to the inverter bridge after filtering to obtain the average current consumption I of the bridge inverter circuit. The circuit is as follows: Figure 2 As shown in , it is composed of resistors R1B-R5B, capacitor C1B, linear optocoupler U2B and operational amplifier OP2;

[0027] (3): The power judgment module calculates the voltage and current obtained by the voltage detection module and the current detection module to obtain the current power P and the power threshold P th Compare and judge the arc status of the spray gun. U1 performs calculation and status judgment.

[0028] (4): After a certain delay T of the delay unit delay After that, confirm the arc state of the spray gun again and adjust T delay Adjustable detection sensitivity, T delay The delay is generated by U1.

[0029] In summary: the utility model adopts the voltage detection module, the current detection module, the power judgment module, and the delay unit, and does not need to directly detect the high voltage electric field on the electrode of the plasma spray gun. It can judge the arc state of the spray gun by detecting the power of the atmospheric plasma power supply, effectively achieving the detection purpose, and at the same time the cost is low; in addition, by adjusting the delay unit time T delay , the sensitivity of the spray gun arc state detection can be flexibly modified, while taking into account the anti-interference and rapidity of the detection circuit.

[0030] It is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or basic features of the present invention. Therefore, no matter from which point of view, the embodiments should be regarded as exemplary and non-restrictive, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention.

[0031] In addition, it should be understood that although this specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment have also been appropriately combined to form other implementation modes that are easy for those skilled in the art to understand.

Claims

1. An abnormal arc detection circuit for a spray gun of an atmospheric plasma power supply, comprising a voltage detection module, a current detection module, a power judgment module, a delay unit, a full-bridge rectifier filter module, a bridge inverter boost module and a plasma spray gun, characterized in that: The input end of the full-bridge rectifier and filter module is connected to the industrial frequency voltage, and the output end of the full-bridge rectifier and filter module is respectively connected to the bridge inverter boost module, the voltage detection module and the current detection module. The bridge inverter boost module is also connected to the plasma spray gun. The voltage detection module and the current detection module are simultaneously connected to the power judgment module. The power judgment module is connected to the delay unit, and the delay unit is connected to the bridge inverter boost module.

2. The abnormal arc detection circuit for a spray gun of an atmospheric plasma power supply according to claim 1, characterized in that: The full-bridge rectifier and filter module includes a rectifier BD1, a capacitor C1, a resistor R1 and a resistor R2. The two input ends of the rectifier BD1 are respectively connected to the AC neutral line and the live line. An output end of the rectifier BD1 is connected to the capacitor C1, the resistor R1 and the bridge inverter boost module. The other end of the resistor R1 is connected to the resistor R2 and the voltage detection module. The other end of the capacitor C1 is connected to the other end of the resistor R2, the other output end of the rectifier BD1 and the ground end.

3. The abnormal arc detection circuit for a spray gun of an atmospheric plasma power supply according to claim 2, characterized in that: The voltage detection module includes a linear optocoupler U2A, a resistor R1A, a resistor R2A, a resistor R3A, a resistor R4A, a resistor R5A, an amplifier OP1 and a capacitor C1A, one end of the resistor R1A is connected to the linear optocoupler U2A, the other end of the resistor R1A is connected to the resistor R3A and the positive input end of the amplifier OP1, the inverting input end of the amplifier OP1 is connected to the resistor R2A and the resistor R4A, the other end of the resistor R4A is connected to the output end of the amplifier OP1 and the resistor R5A, the other end of the resistor R5A is connected to the capacitor C1A and the MCU, and the other end of the capacitor C1A is grounded.

4. The abnormal arc detection circuit for a spray gun of an atmospheric plasma power supply according to claim 3, characterized in that: The current detection module includes a linear optocoupler U2B, a resistor R1B, a resistor R2B, a resistor R3B, a resistor R4B, a resistor R5B, an amplifier OP2 and a capacitor C1B, one end of the resistor R1B is connected to the linear optocoupler U2B, the other end of the resistor R1B is connected to the resistor R3B and the positive input end of the amplifier OP2, the inverting input end of the amplifier OP2 is connected to the resistor R2B and the resistor R4B, the other end of the resistor R4B is connected to the output end of the amplifier OP2 and the resistor R5B, the other end of the resistor R5B is connected to the capacitor C1B and the MCU, and the other end of the capacitor C1B is grounded.

5. The abnormal arc detection circuit for a spray gun of an atmospheric plasma power supply according to claim 1, characterized in that: The power judgment module and the delay unit are implemented by using an 8-bit microcontroller MCU.

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