A corona machine control circuit

Abstract

The application discloses a corona machine control circuit, comprising a voltage reduction circuit, a current signal processing module, an adjustable parallel resonant circuit, a voltage signal processing module and a signal receiving module; the voltage reduction circuit is used for adjusting the bus DC voltage, the voltage reduction circuit comprises a current sensor, the current sensor is used for collecting the current signal output by the voltage reduction circuit and transmitting to the current signal processing module; the adjustable parallel resonant circuit comprises a first capacitor and a transformer, and the first capacitor is connected to the output end of the transformer. The current sensor is used for sampling the current of the bus and transmitting to the current signal processing module, so that the current in the circuit is monitored in real time, the voltage reduction circuit is controlled by using the driving module in the current signal processing module, the output voltage and current are realized by adjusting the bus DC voltage, compared with the traditional mode realized by adjusting the duty cycle of the H bridge, the mode has the advantages of ideal waveform and high efficiency.

Description

Technical Field

[0001] This invention relates to the field of corona machine control circuits, and in particular to a corona machine control circuit. Background Technology

[0002] A corona discharge machine control circuit is a device for surface pretreatment of silicone rubber, plastics, and other materials. It utilizes high-frequency, high-voltage corona discharge on the surface of the plastic being treated to generate low-temperature plasma, causing a free radical reaction on the plastic surface and leading to polymer cross-linking. This roughens the surface and increases its wettability to polar solvents. The electrical control section of the corona discharge machine control circuit is available in two power options: single-phase 220V / 50kHz and three-phase 380V / 50kHz, with power ranging from 1kW to 60kW, output frequency from 15kHz to 25kHz, and continuously adjustable output voltage from 0 to 15kV. In existing corona discharge machine control circuits, power regulation is achieved by adjusting the duty cycle of the H-bridge. Traditionally, this involves using a fixed frequency or manual frequency adjustment to regulate the output power, in conjunction with a series resonant circuit to adjust the circuit's resonant state.

[0003] However, the existing corona machine control circuits use the H-bridge duty cycle to adjust power and frequency, which results in low efficiency and irrational waveforms. Traditional frequency adjustment methods cannot adjust the circuit frequency steplessly based on real-time current and voltage conditions, which can easily lead to excessively high or low current or voltage, resulting in an unsatisfactory circuit resonance state and affecting circuit operation. Summary of the Invention

[0004] The purpose of this invention is to provide a corona machine control circuit to achieve automatic frequency tracking and adjustment.

[0005] To solve the above-mentioned technical problems, the present invention provides a corona machine control circuit, including a step-down circuit, a current signal processing module, an adjustable parallel resonant circuit, a voltage signal processing module, and a signal receiving module;

[0006] The step-down circuit is used to regulate the DC voltage of the bus. The step-down circuit includes a current sensor, which is used to collect the current signal output by the step-down circuit and transmit it to the current signal processing module.

[0007] The adjustable parallel resonant circuit includes a first capacitor and a transformer, with the first capacitor connected to the output terminal of the transformer.

[0008] The voltage signal processing module is electrically connected to the upper plate and the lower plate of the first capacitor respectively. The first signal processing module is used to monitor the voltage at the output terminal of the transformer and transmit it to the signal receiving module.

[0009] The signal receiving module includes a signal receiving unit and a driving circuit. The signal receiving unit is used to receive signals from the current signal processing module and the voltage signal processing module, process the received signals and feed them back to the driving circuit. The driving circuit is used to control the output frequency of the adjustable parallel resonant circuit.

[0010] Furthermore, the step-down circuit also includes a first power transistor and a first inductor; a second capacitor is connected to the second pin of the first power transistor, a resistor is connected to the upper plate of the second capacitor, the other end of the resistor is connected to the first pin of the first power transistor and one end of the first inductor, and the gate of the first power transistor is connected to the current sensor.

[0011] Furthermore, the current signal processing module controls the on and off states of the first power transistor.

[0012] Furthermore, the parallel resonant circuit also includes a second inductor, a third inductor, a second power transistor, a third power transistor, a first diode, and a second diode; one end of the second inductor is connected to the first output terminal of the transformer, and the other end of the second inductor is connected to the upper plate of the first capacitor; one end of the third inductor is connected to the second output terminal of the transformer, and the other end of the third inductor is connected to the lower plate of the first capacitor; the third pins of the second power transistor and the third power transistor are respectively connected to the output terminal of the first diode, the second pins of the second power transistor and the third power transistor are respectively connected to the input terminal of the second diode, the gates of the second power transistor and the third power transistor are both electrically connected to the signal processing module, the first pin of the second power transistor is connected to the lower plate of the first capacitor, and the first pin of the third power transistor is connected to the upper plate of the first capacitor.

[0013] Furthermore, the signal processing module is electrically connected to the gates of the second power transistor and the third power transistor.

[0014] Furthermore, the driving circuit adjusts the circuit resonance state by controlling the conduction and closure of the second power transistor and the third power transistor.

[0015] Furthermore, it also includes a current controller and a current contactor, wherein the current controller is electrically connected to the current contactor, and the other end of the current contactor is connected to an output circuit.

[0016] Furthermore, it also includes a rectifier circuit, a filter circuit, a first auxiliary circuit, and a second auxiliary circuit. The input terminal of the rectifier circuit is electrically connected to the output terminal of the current controller, the input terminal of the filter circuit is electrically connected to the output terminal of the rectifier circuit, the first auxiliary circuit is connected in series with the first power transistor, and the second auxiliary circuit is connected in parallel with the parallel resonant circuit.

[0017] Compared with the prior art, the present invention has at least the following beneficial effects:

[0018] 1. The current of the bus is sampled by the current sensor and transmitted to the current signal processing module to monitor the current in the circuit in real time. The current signal processing module uses the drive module to control the step-down circuit and adjust the DC voltage of the bus to realize the output voltage and current. Compared with the traditional method of adjusting the duty cycle of the H-bridge, it has the advantages of ideal waveform and high efficiency.

[0019] 2. By replacing the traditional series resonant circuit with a parallel resonant circuit, the voltage signal of the parallel resonant circuit is collected by the voltage signal processing module and transmitted to the signal processing module. The resonant state of the parallel resonant circuit is monitored in real time to see if it is in the optimal resonant state. The circuit frequency is adjusted according to the circuit load to achieve automatic frequency tracking, which is beneficial to the improvement of circuit operation and efficiency. Attached Figure Description

[0020] Figure 1 This is a block diagram of the control circuit principle of the corona machine of the present invention;

[0021] Figure 2 This is a schematic diagram of the control circuit for the corona machine of the present invention. Detailed Implementation

[0022] The corona machine control circuit of the present invention will now be described in more detail with reference to the schematic diagrams, which illustrate preferred embodiments of the invention. It should be understood that those skilled in the art can modify the invention described herein while still achieving its advantageous effects. Therefore, the following description should be understood as being of general knowledge to those skilled in the art and is not intended to limit the invention.

[0023] The invention is described more specifically by way of example in the following paragraphs with reference to the accompanying drawings. The advantages and features of the invention will become clearer from the following description and claims. It should be noted that the drawings are in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of the invention.

[0024] like Figure 1-2As shown in the figure, an embodiment of the present invention proposes a corona machine control circuit, including a step-down circuit, a current signal processing module B001, an adjustable parallel resonant circuit, a voltage signal processing module B004, and a signal receiving module B005.

[0025] The step-down circuit is used to regulate the DC voltage of the bus. The step-down circuit includes a current sensor LEM1, which is used to collect the current signal output by the step-down circuit and transmit it to the current signal processing module B001. The step-down circuit also includes a first power transistor Q1 and a first inductor L1. The second pin of the first power transistor Q1 is connected to a second capacitor C22. The upper plate of the second capacitor C22 is connected to a resistor R7. The other end of the resistor R7 is connected to the first pin of the first power transistor Q1 and one end of the first inductor L1. The gate of the first power transistor Q1 is connected to the current sensor LEM1. The current signal processing module B001 controls the conduction and closure of the first power transistor Q1.

[0026] In this embodiment, the current signal processing module B001 is connected to the first power transistor Q1 and the current sensor LEM1 to achieve real-time monitoring of the bus current. When the bus current is detected to be too low, the current signal processing module B001 outputs a high level, the first power transistor Q1 is turned on, the first inductor L1 is magnetized, and the current flowing through the first inductor L1 increases linearly. When the bus current is detected to be too high, the current signal processing module B001 outputs a low level, the first power transistor Q1 is turned off, and the current flowing through the first inductor L1 decreases linearly. Adjusting the bus DC voltage to achieve the output voltage and current has the advantages of ideal waveform and high efficiency compared to the traditional method of adjusting the duty cycle of the H-bridge.

[0027] The adjustable parallel resonant circuit includes a first capacitor C5 and a transformer T1. The first capacitor C5 is connected to the output terminal of the transformer T1. The voltage signal processing module B004 is electrically connected to the upper and lower plates of the first capacitor C5 respectively. The voltage signal processing module is used to monitor the voltage at the output terminal of the transformer T1 and transmit it to the signal receiving module B005. The signal receiving module B005 includes a signal receiving unit and a driving circuit. The signal receiving unit is used to receive signals from the current signal processing module B001 and the voltage signal processing module B004, process the received signals, and feed them back to the driving circuit. The driving circuit is used to control the output frequency of the adjustable parallel resonant circuit.

[0028] Specifically, the parallel resonant circuit further includes a second inductor L2, a third inductor L3, a second power transistor Q2, a third power transistor Q3, a first diode D4, and a second diode D5; one end of the second inductor L2 is connected to the first output terminal of the transformer T1, and the other end of the second inductor L2 is connected to the upper plate of the first capacitor C5; one end of the third inductor L3 is connected to the second output terminal of the transformer T1, and the other end of the third inductor L3 is connected to the lower plate of the first capacitor C5; the third pins of the second power transistor Q2 and the third power transistor Q3 are respectively connected to the output terminal of the first diode D4, and the second power transistor... The second pins of Q2 and the third power transistor Q3 are respectively connected to the input terminal of the second diode D5. The gates of the second power transistor Q2 and the third power transistor Q3 are both electrically connected to the signal processing module. The first pin of the second power transistor Q2 is connected to the lower plate of the first capacitor C5, and the first pin of the third power transistor Q3 is connected to the upper plate of the first capacitor C5. The second voltage signal processing module B004 is connected to the input terminal of the transformer T1 and is used to sample the high voltage of the transformer T1. The driving circuit adjusts the circuit resonance state by controlling the conduction and closure of the second power transistor Q2 and the third power transistor Q3.

[0029] In this embodiment, a parallel resonant circuit replaces the traditional series resonant circuit. The voltage signal processing module B004 collects the voltage signal of the parallel resonant circuit and transmits it to the signal processing module to monitor the resonant state of the parallel resonant circuit in real time. Based on the voltage situation in the resonant circuit, it is determined whether the resonant circuit is in the optimal resonant state. The driving circuit outputs a high level or a low level to control the conduction and disconnection of the second power transistor Q2 and the third power transistor Q3, thereby realizing stepless adjustment of the circuit frequency, which is beneficial to improving the circuit operation and efficiency.

[0030] Specifically, the voltage sampling results of the current signal processing module B001 and the voltage signal processing module B004 are processed by the signal receiving module B005 to achieve automatic frequency tracking adjustment, so that the entire system works dynamically in the optimal resonance state.

[0031] Specifically, the corona machine control circuit also includes a current controller and a current contactor. The current controller is electrically connected to the current contactor, and the other end of the current contactor is connected to an output circuit.

[0032] 380V AC power is output from the current controller and stepped down to 220V DC power via a step-down converter in the output circuit, which is used to power other parts of the corona machine control circuit.

[0033] Furthermore, the corona machine control circuit also includes a rectifier circuit and a filter circuit. The input terminal of the rectifier circuit is electrically connected to the output terminal of the current controller, and the input terminal of the filter circuit is electrically connected to the output terminal of the rectifier circuit.

[0034] In this embodiment, the 380V three-phase AC power is converted into a DC current of about 510V through a bridge rectifier circuit and a filter circuit with four capacitors in parallel, and then sent to the auxiliary circuit, the step-down circuit and the parallel resonant power.

[0035] In summary, the present invention has the following beneficial effects:

[0036] A step-down circuit consisting of a first power transistor Q1, a first inductor L1, a current sensor LEM1, and a current signal processing module B001 transmits the signal collected by the current sensor LEM1 to the current signal processing module B001 for processing. The current signal processing module B001 outputs high and low levels to control the conduction and disconnection of the power transistor Q1, thereby adjusting the DC bus voltage to achieve the output voltage and current. Compared with the traditional method of adjusting the duty cycle of the H-bridge, this method has advantages such as ideal waveform and high efficiency.

[0037] An adjustable parallel resonant circuit is composed of a first capacitor C5, a second inductor L2, a third inductor L3, and a transformer T1. Stepless adjustment is achieved by changing the gap between the magnetic cores of the second inductor L2 and the third inductor L3.

[0038] The results from the current signal processing module B001 and the voltage signal processing module B004 are processed by the signal receiving module B005. This enables automatic frequency tracking adjustment, allowing the entire system to operate dynamically at its optimal resonance state. Compared to traditional fixed-frequency or manual frequency adjustment methods, this approach improves circuit operation and efficiency.

[0039] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A corona machine control circuit, characterized in that, It includes a step-down circuit, a current signal processing module, an adjustable parallel resonant circuit, a voltage signal processing module, a second auxiliary circuit, and a signal receiving module; The step-down circuit is used to regulate the DC voltage of the bus. The step-down circuit includes a current sensor, which is used to collect the current signal output by the step-down circuit and transmit it to the current signal processing module. The adjustable parallel resonant circuit includes a first capacitor and a transformer, wherein the first capacitor is connected to the input terminal of the transformer. The voltage signal processing module is electrically connected to the upper plate and the lower plate of the first capacitor respectively. The voltage signal processing module is used to monitor the voltage at the input terminal of the transformer and transmit it to the signal receiving module. The signal receiving module includes a signal receiving unit and a driving circuit. The signal receiving unit is used to receive signals from the current signal processing module and the voltage signal processing module, process the received signals and feed them back to the driving circuit. The driving circuit is used to control the output frequency of the adjustable parallel resonant circuit. The parallel resonant circuit further includes a second inductor, a third inductor, a second power module, a third power module, a first diode module, and a second diode module. The input terminal of the first diode module is connected to the output terminal of the step-down circuit. Both the first and second diode modules include two diodes connected in parallel. Both the second and third power modules include two power transistors connected in series. One end of the second inductor is connected to the first input terminal of the transformer, and the other end of the second inductor is connected to the upper plate of the first capacitor. One end of the third inductor is connected to the second input terminal of the transformer, and the other end of the third inductor is connected to the lower plate of the first capacitor. The third pins of the second power module and the third power module are respectively connected to the output terminal of the first diode module. The third pins of the power module and the third power module are respectively the input terminals of the second power module and the third power module. The second pins of the second power module and the third power module are respectively connected to the input terminal of the second diode module. The output terminal of the second diode module is connected to the second auxiliary circuit. The second pins of the second power module and the third power module are respectively the output terminals of the second power module and the third power module. The first pin of the second power module is connected to the lower plate of the first capacitor. The first pin of the third power module is connected to the upper plate of the first capacitor. The first pin of the second power module is the connection point of the two power transistors of the second power module connected in series. The first pin of the third power module is the connection point of the two power transistors of the third power module connected in series. The driving circuit adjusts the circuit resonance state by controlling the conduction and closure of the second power module and the third power module.

2. The corona machine control circuit as described in claim 1, characterized in that, The step-down circuit further includes a first power module and a first inductor; a second capacitor is connected to the second pin of the first power module, a resistor is connected to the upper plate of the second capacitor, the other end of the resistor is connected to the first pin of the first power module and one end of the first inductor, and the gate of the first power module is connected to the current signal processing module.

3. The corona machine control circuit as described in claim 1, characterized in that, The current signal processing module controls the switching on and off of the first power module.

4. The corona machine control circuit as described in claim 1, characterized in that, The signal processing module is electrically connected to the gates of the second power module and the third power module.

5. The corona machine control circuit as described in claim 1, characterized in that, It also includes a current controller and a current contactor, the current controller being electrically connected to the current contactor, and the other end of the current contactor being connected to an output circuit.

6. The corona machine control circuit as described in claim 5, characterized in that, It also includes a rectifier circuit and a filter circuit. The input terminal of the rectifier circuit is electrically connected to the output terminal of the current controller, and the input terminal of the filter circuit is electrically connected to the output terminal of the rectifier circuit.

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