Direct-current arc power supply circuit, circuit board and electrical equipment

Abstract

The invention belongs to the technical field of power circuits, and particularly relates to a direct-current arc power circuit, a circuit board and electrical equipment, the direct-current arc power circuit comprises a rectification unit, a DC / DC conversion unit, an arc control unit and an electrode unit, the rectification unit is connected with an external alternating-current mains supply, and the external alternating-current mains supply transmits alternating current to the rectification unit; the rectification unit rectifies alternating current into direct current and transmits the direct current to the DC / DC conversion unit, the arc control unit sends a PWM signal to the DC / DC conversion unit, and the DC / DC conversion unit adjusts the direct current according to the PWM signal and transmits the adjusted direct current to the electrode unit, so that the electrode unit generates direct current arc. The direct-current arc power supply circuit generates a direct-current arc, a current zero crossing point is not needed, and arc extinguishing is not easy, so that the arc with extremely high stability can be provided, and the arc is used for industrial application such as metal welding and cutting.

Description

Technical Field

[0001] The present invention belongs to the technical field of power supply circuits, and in particular relates to a direct current arc power supply circuit, a circuit board and an electrical device. Background Art

[0002] Arc power supplies are widely used in industrial applications, such as metal welding and cutting. The commonly used arc power supply is the AC arc power supply. Its working principle is that in an AC circuit, when the voltage between the two electrodes is high enough, the gas between the electrodes is broken down and ionized to form a conductive channel, and the current will flow through this channel, accompanied by a strong light-emitting and heating effect, thereby generating an arc. As the AC current changes periodically, the voltage also periodically passes through zero, and the arc will periodically extinguish and reignite. For example, when a common AC welding machine is working, the welding rod and the weldment are in the arc starting stage. First, the initial arc is formed by breaking down the air and other media through a momentary high voltage, and then the arc is maintained under the continuous action of the AC power supply for welding metal materials. However, the AC arc power supply has the problem of easy arc extinguishing when the current passes through the zero point, and the stability is poor. Summary of the invention

[0003] Based on this, the purpose of the present invention is to provide a DC arc power supply circuit, a circuit board and an electrical device to fundamentally solve the problem that the existing AC arc power supply is easy to extinguish the arc when the current passes through zero point and has poor stability.

[0004] An embodiment of the present invention is implemented as follows: a DC arc power supply circuit is provided, the DC arc power supply circuit includes a rectifier unit, a DC / DC conversion unit, an arc control unit and an electrode unit, the rectifier unit is connected to an external AC mains, the external AC mains transmits AC power to the rectifier unit, the rectifier unit rectifies the AC power into DC power and transmits the DC power to the DC / DC conversion unit, the arc control unit sends a PWM signal to the DC / DC conversion unit, the DC / DC conversion unit adjusts the DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit, so that the electrode unit generates a DC arc.

[0005] In some embodiments, the rectifier unit includes a first group of diodes, a second group of diodes and a third group of diodes, the first group of diodes includes a first diode and a second diode, the A phase of the external AC mains is connected to the positive electrode of the first diode and the negative electrode of the second diode, the negative electrode of the first diode is connected to the DC / DC conversion unit, and the positive electrode of the second diode is connected to the DC / DC conversion unit, the second group of diodes includes a third diode and a fourth diode, the B phase of the external AC mains is connected to the positive electrode of the third diode and the negative electrode of the fourth diode, the negative electrode of the third diode is connected to the DC / DC conversion unit, and the positive electrode of the fourth diode is connected to the DC / DC conversion unit, the third group of diodes includes a fifth diode and a sixth diode, the C phase of the external AC mains is connected to the positive electrode of the fifth diode and the negative electrode of the sixth diode, the negative electrode of the fifth diode is connected to the DC / DC conversion unit, and the positive electrode of the sixth diode is connected to the DC / DC conversion unit.

[0006] In some embodiments, the DC / DC conversion unit includes a first bridge arm topology module and a second bridge arm topology module, the first bridge arm topology module includes a first switch and a seventh diode, the first end of the first switch is connected to the rectifier unit, the second end of the first switch is respectively connected to the cathode of the seventh diode and the electrode unit, the third end of the first switch is connected to the arc control unit, and the anode of the seventh diode is respectively connected to the rectifier unit and the electrode unit, the second bridge arm topology module includes a second switch and an eighth diode, the first end of the second switch is connected to the rectifier unit, the second end of the second switch is respectively connected to the cathode of the eighth diode and the electrode unit, the third end of the second switch is connected to the arc control unit, and the anode of the eighth diode is respectively connected to the rectifier unit and the electrode unit.

[0007] In some embodiments, the arc control unit includes an arc control module, a current sampling module and a voltage sampling module, the current sampling module is connected to the arc control module and the DC / DC conversion unit, the voltage sampling module is connected to the arc control module and the DC / DC conversion unit, the current sampling module collects the output current of the DC / DC conversion unit and sends the output current to the arc control module, the voltage sampling module collects the output voltage of the DC / DC conversion unit and sends the output voltage to the arc control module, the arc control module calculates the first PWM drive signal and the second PWM drive signal according to the output current and the output voltage through a PID algorithm, and sends the first PWM drive signal and the second PWM drive signal to the first switch and the second switch.

[0008] In some embodiments, the arc control module includes a DSP module and an FPGA module, the DSP module is connected to the FPGA module, the current sampling module collects the output current of the DC / DC conversion unit and sends the output current to the DSP module, the voltage sampling module collects the output voltage of the DC / DC conversion unit and sends the output voltage to the DSP module, the DSP module calculates the first PWM control signal and the second PWM control signal according to the output current and the output voltage through a PID algorithm, and sends the first PWM control signal and the second PWM control signal to the FPGA module, the FPGA module converts the first PWM control signal and the second PWM control signal into a first PWM drive signal and a second PWM drive signal, and sends the first PWM drive signal and the second PWM drive signal to the first switch and the second switch.

[0009] In some embodiments, the first switch includes a first switch tube and a ninth diode anti-parallel to the first switch tube, and the first switch tube is a MOSFET tube, an IGBT tube, an IGCT tube or an IEGT tube. The second switch includes a second switch tube and a tenth diode anti-parallel to the second switch tube, and the second switch tube is a MOSFET tube, an IGBT tube, an IGCT tube or an IEGT tube.

[0010] In some embodiments, the DC arc power supply circuit also includes a first filtering unit, the first filtering unit includes a filtering capacitor, the first end of the filtering capacitor is respectively connected to the rectifying unit and the DC / DC conversion unit, and the second end of the filtering capacitor is respectively connected to the rectifying unit and the DC / DC conversion unit.

[0011] In some embodiments, the DC arc power supply circuit also includes a second filtering unit, the second filtering unit includes a first inductor, a second inductor, a third inductor and a fourth inductor, the first end of the first inductor is connected to the DC / DC conversion unit, the second end of the first inductor is respectively connected to the electrode unit and the second end of the second inductor, the first end of the second inductor is connected to the DC / DC conversion unit, the first end of the third inductor is connected to the DC / DC conversion unit, the second end of the third inductor is respectively connected to the electrode unit and the second end of the fourth inductor, and the first end of the fourth inductor is connected to the DC / DC conversion unit.

[0012] Another embodiment of the present invention further provides a circuit board, comprising the DC arc power supply circuit as described in any one of the above items.

[0013] Another embodiment of the present invention further provides an electrical device, comprising the circuit board as described above.

[0014] The embodiment of the present invention provides a DC arc power supply circuit, a circuit board and an electrical device. The DC arc power supply circuit includes a rectifier unit, a DC / DC conversion unit, an arc control unit and an electrode unit. The rectifier unit is connected to an external AC mains, and the external AC mains transmits the AC power to the rectifier unit. The rectifier unit rectifies the AC power into DC power and transmits the DC power to the DC / DC conversion unit. The arc control unit sends a PWM signal to the DC / DC conversion unit. The DC / DC conversion unit adjusts the DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit, so that the electrode unit generates a DC arc. The DC arc power supply circuit generates a DC arc without the need for the current to cross the zero point, and the arc is not easily extinguished, so that an arc with extremely high stability can be provided, so that the arc can be used for industrial applications such as metal welding and cutting. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a structural block diagram of a DC arc power supply circuit provided in an embodiment of the present invention; Figure 2 is a circuit diagram of a DC arc power supply circuit provided in an embodiment of the present invention; Figure 3 is a working principle diagram of an arc control unit provided in an embodiment of the present invention; Figure 4 It is a modulation principle diagram of the first PWM drive signal and the second PWM drive signal provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention. In addition, it should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0017] In the description of the present invention, it is necessary to understand that the terms "length", "width", "up", "down", "left", "right", "horizontal", "top", "bottom", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0018] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0019] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0020] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0021] The disclosure below provides many different embodiments or examples to realize different structures of the present invention. In order to simplify the disclosure of the present invention, the parts and settings of specific examples are described below. Of course, they are only examples, and the purpose is not to limit the present invention. In addition, the present invention can repeat reference numbers and / or reference letters in different examples, and this repetition is for the purpose of simplification and clarity, which itself does not indicate the relationship between the various embodiments and / or settings discussed. In addition, the examples of various specific processes and materials provided by the present invention, but those of ordinary skill in the art can be aware of the application of other processes and / or the use of other materials.

[0022] refer to Figure 1 and Figure 2An embodiment of the present invention provides a DC arc power supply circuit, which includes a rectifier unit 20, a DC / DC conversion unit 40, an arc control unit 50 and an electrode unit 70. The rectifier unit 20 is connected to an external AC mains 10, and the external AC mains 10 transmits AC power to the rectifier unit 20. The rectifier unit 20 rectifies the AC power into DC power and transmits the DC power to the DC / DC conversion unit 40. The arc control unit 50 sends a PWM signal to the DC / DC conversion unit 40. The DC / DC conversion unit 40 adjusts the DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit 70, so that the electrode unit 70 generates a DC arc.

[0023] In this embodiment, the external AC mains 10 is a three-phase AC mains. The external AC mains 10 transmits the three-phase AC power to the rectifier unit 20. The rectifier unit 20 rectifies the three-phase AC power into DC power, and transmits the DC power to the DC / DC conversion unit 40. The arc control unit 50 sends a PWM signal to the DC / DC conversion unit 40 to control the arc current. The DC / DC conversion unit 40 adjusts the DC power according to the PWM signal to ensure stable DC output, and then transmits the adjusted DC power to the electrode unit 70 so that the electrode unit 70 generates a DC arc.

[0024] In some embodiments, the electrode unit 70 includes a positive graphite electrode and a negative graphite electrode. The DC arc power supply circuit can be applied to electrical equipment, such as welding machines and cutting machines. During the operation of the electrical equipment, the positive graphite electrode and the negative graphite electrode are first short-circuited, and then the gap is slowly opened. The positive graphite electrode and the negative graphite electrode receive the regulated DC power, and a DC arc is generated between the gaps of the positive graphite electrode and the negative graphite electrode.

[0025] In the DC arc power supply circuit provided by the present invention, the DC arc power supply circuit includes a rectifier unit 20, a DC / DC conversion unit 40, an arc control unit 50 and an electrode unit 70. The rectifier unit 20 is connected to an external AC mains 10, and the external AC mains 10 transmits AC power to the rectifier unit 20. The rectifier unit 20 rectifies the AC power into DC power and transmits the DC power to the DC / DC conversion unit 40. The arc control unit 50 sends a PWM signal to the DC / DC conversion unit 40. The DC / DC conversion unit 40 adjusts the DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit 70, so that the electrode unit 70 generates a DC arc. The DC arc power supply circuit generates a DC arc without the need for current zero crossing, and is not easy to extinguish the arc, thereby being able to provide an arc with extremely high stability, so that the arc can be used for industrial applications such as metal welding and cutting.

[0026] refer to Figure 2In some specific embodiments of the present invention, the rectifier unit 20 includes a first group of diodes, a second group of diodes and a third group of diodes, the first group of diodes includes a first diode D1 and a second diode D2, the A phase of the external AC mains 10 is connected to the positive electrode of the first diode D1 and the negative electrode of the second diode D2, the negative electrode of the first diode D1 is connected to the DC / DC conversion unit 40, the positive electrode of the second diode D2 is connected to the DC / DC conversion unit 40, the second group of diodes includes a third diode D3 and a fourth diode D4, the B phase of the external AC mains 10 is connected to the positive electrode of the first diode D1 and the negative electrode of the second diode D2, the negative electrode of the first diode D1 is connected to the DC / DC conversion unit 40, the positive electrode of the second diode D2 is connected to the DC / DC conversion unit 40, the second group of diodes includes a third diode D3 and a fourth diode D4, The positive electrode of the third diode D3 and the negative electrode of the fourth diode D4 are connected, the negative electrode of the third diode D3 is connected to the DC / DC conversion unit 40, the positive electrode of the fourth diode D4 is connected to the DC / DC conversion unit 40, the third group of diodes includes a fifth diode D5 and a sixth diode D6, the C phase of the external AC mains 10 is connected to the positive electrode of the fifth diode D5 and the negative electrode of the sixth diode D6, the negative electrode of the fifth diode D5 is connected to the DC / DC conversion unit 40, and the positive electrode of the sixth diode D6 is connected to the DC / DC conversion unit 40.

[0027] In this embodiment, the rectifier unit 20 forms a three-phase full-wave rectifier bridge through the first group of diodes, the second group of diodes and the third group of diodes, and each group of diodes corresponds to each phase of the three-phase AC mains. In one cycle of the three-phase AC mains, the diodes of different phases are turned on in turn through the unidirectional conductivity of the diodes to convert the three-phase AC mains into DC power.

[0028] Specifically, taking the three phases A, B, and C of the three-phase AC mains as an example, at different stages of the three-phase AC voltage waveform, the diode to be turned on is determined according to the magnitude relationship of the instantaneous values ​​of the three-phase AC voltage. When the instantaneous value of the voltage of one phase is the highest among the three phases, and the instantaneous value of the voltage of another phase is the lowest among the three phases, the corresponding diode connecting the two phases is turned on, and the positive half-cycle voltage of this phase is led to the positive pole of the DC output, and the negative half-cycle voltage is led to the negative pole of the DC output, thereby achieving rectification. For example, at a certain moment, the voltage of phase A is the highest and the voltage of phase B is the lowest. At this time, the first diode D1 (forward diode) connected to phase A and the fourth diode D4 (reverse diode) connected to phase B are turned on, and the current flows out of phase A and returns to phase B. In this cycle, the appropriate voltage part is continuously taken out from the three-phase AC, and finally a relatively smooth DC is obtained at the output end.

[0029] refer to Figure 2In some specific embodiments of the present invention, the DC / DC conversion unit 40 includes a first bridge arm topology module and a second bridge arm topology module, the first bridge arm topology module includes a first switch Q1 and a seventh diode D7, the first end of the first switch Q1 is connected to the rectifier unit 20, the second end of the first switch Q1 is respectively connected to the cathode of the seventh diode D7 and the electrode unit 70, the third end of the first switch Q1 is connected to the arc control unit 50, and the anode of the seventh diode D7 is respectively connected to the rectifier unit 20 and the electrode unit 70, the second bridge arm topology module includes a second switch Q2 and an eighth diode D8, the first end of the second switch Q2 is connected to the rectifier unit 20, the second end of the second switch Q2 is respectively connected to the cathode of the eighth diode D8 and the electrode unit 70, the third end of the second switch Q2 is connected to the arc control unit 50, and the anode of the eighth diode D8 is respectively connected to the rectifier unit 20 and the electrode unit 70.

[0030] In this embodiment, the first switch Q1 and the seventh diode D7 are connected in series between the DC bus, wherein the first end of the first switch Q1 is connected to the positive end of the DC bus, the second end of the first switch Q1 is connected to the cathode of the seventh diode D7, the anode of the seventh diode D7 is connected to the negative end of the DC bus, the second end of the first switch Q1 and the cathode of the seventh diode D7 are connected as the positive output end of the DC / DC conversion unit 40, and the anode of the seventh diode D7 is used as the negative output end of the DC / DC conversion unit 40. The second switch Q2 and the eighth diode D8 are connected in series between the DC bus, wherein the first end of the second switch Q2 is connected to the positive end of the DC bus, the second end of the second switch Q2 is connected to the cathode of the eighth diode D8, the anode of the eighth diode D8 is connected to the negative end of the DC bus, the second end of the second switch Q2 and the cathode of the eighth diode D8 are connected as the positive output end of the DC / DC conversion unit 40, and the anode of the eighth diode D8 is used as the negative output end of the DC / DC conversion unit 40.

[0031] The rectifier unit 20 transmits the rectified DC power to the DC / DC conversion unit 40, and the arc control unit 50 sends a PWM signal to the DC / DC conversion unit 40, and controls the on and off of the first switch Q1 and the second switch Q2 to regulate the DC power and ensure stable DC output, and then transmits the regulated DC power to the electrode unit 70, so that the electrode unit 70 generates a DC arc.

[0032] refer to Figure 2 and Figure 3In some specific embodiments of the present invention, the arc control unit 50 includes an arc control module, a current sampling module and a voltage sampling module. The current sampling module is connected to the arc control module and the DC / DC conversion unit 40, and the voltage sampling module is connected to the arc control module and the DC / DC conversion unit 40. The current sampling module collects the output current of the DC / DC conversion unit 40 and sends the output current to the arc control module. The voltage sampling module collects the output voltage of the DC / DC conversion unit 40 and sends the output voltage to the arc control module. The arc control module calculates the first PWM drive signal and the second PWM drive signal according to the output current and the output voltage through a PID algorithm, and sends the first PWM drive signal and the second PWM drive signal to the first switch Q1 and the second switch Q2.

[0033] The current sampling module is connected to the positive output terminal of the DC / DC conversion unit 40 to collect the output current of the DC / DC conversion unit 40. For example, the current acquisition module includes a Hall current sensor, which collects the output current of the DC / DC conversion unit 40 through the Hall current sensor and transmits the output current to the arc control module. Of course, the current acquisition module can also be implemented in other ways as long as the current acquisition function can be realized, which will not be described in detail here.

[0034] The voltage sampling module is connected as follows Figure 2 The A and B terminals shown are used to collect the output voltages of the A and B terminals, that is, to collect the output voltage of the DC / DC conversion unit 40. For example, the voltage sampling module includes a voltage divider circuit and an operational amplifier, which proportionally reduces the voltage of the A and B terminals to a suitable voltage range through the voltage divider circuit, and the operational amplifier amplifies the signal and transmits the signal amplified to a suitable amplitude range to the arc control module. Of course, the voltage acquisition module can also be implemented in other ways as long as the voltage acquisition function can be realized, which will not be described here one by one.

[0035] The current sampling module collects the output current of the DC / DC conversion unit 40 and sends the output current to the arc control module. The voltage sampling module collects the output voltage of the DC / DC conversion unit 40 and sends the output voltage to the arc control module. The arc control module calculates the first PWM drive signal and the second PWM drive signal through the PID algorithm according to the output current and the output voltage, and sends the first PWM drive signal and the second PWM drive signal to the first switch Q1 and the second switch Q2 to control the conduction and shutdown of the first switch Q1 and the second switch Q2.

[0036] Among them, the PID algorithm can be implemented by setting the target value and initialization parameters, calculating the deviation, calculating the PID, and obtaining the PWM signal. First, determine the target values ​​of the output current and output voltage of the desired DC / DC converter, and initialize the PID parameters. Then, according to the actual output current and actual output voltage collected, as well as the set target values ​​of the output current and output voltage, calculate the current deviation and voltage deviation, and then calculate the comprehensive deviation. Then perform PID calculation to obtain the proportional term P, the integral term I, and the differential term D. Add the proportional term P, the integral term I, and the differential term D to obtain the output value, which needs to be mapped and converted according to the PWM modulation range to obtain the corresponding PWM signal duty cycle, that is, to obtain the first PWM drive signal and the second PWM drive signal.

[0037] refer to Figure 2 and Figure 3 In some specific embodiments of the present invention, the arc control module includes a DSP module and an FPGA module, the DSP module is connected to the FPGA module, the current sampling module collects the output current of the DC / DC conversion unit 40 and sends the output current to the DSP module, the voltage sampling module collects the output voltage of the DC / DC conversion unit 40 and sends the output voltage to the DSP module, the DSP module calculates the first PWM control signal and the second PWM control signal according to the output current and the output voltage through a PID algorithm, and sends the first PWM control signal and the second PWM control signal to the FPGA module, the FPGA module converts the first PWM control signal and the second PWM control signal into a first PWM drive signal and a second PWM drive signal, and sends the first PWM drive signal and the second PWM drive signal to the first switch Q1 and the second switch Q2.

[0038] A DSP (Digital Signal Processor) module is an integrated circuit chip or a functional module in a chip that is specifically used for digital signal processing and has the ability to efficiently process large amounts of digital signal data.

[0039] FPGA (Field Programmable Gate Array) module is an integrated circuit chip that can be programmed to change its internal logic functions. It consists of a large number of programmable logic units, programmable wiring resources, and input and output pins. According to specific application requirements, hardware description languages ​​(such as Verilog, VHDL, etc.) can be used to define its internal logic circuit structure and realize various digital circuit functions.

[0040] The current sampling module collects the output current of the DC / DC conversion unit 40 and sends the output current to the DSP module. The voltage sampling module collects the output voltage of the DC / DC conversion unit 40 and sends the output voltage to the DSP module. The DSP module calculates the first PWM control signal and the second PWM control signal through the PID algorithm according to the output current and the output voltage, and sends the first PWM control signal and the second PWM control signal to the FPGA module. The FPGA module converts the first PWM control signal and the second PWM control signal into the first PWM drive signal and the second PWM drive signal, and sends the first PWM drive signal and the second PWM drive signal to the first switch Q1 and the second switch Q2 to realize the control of the first switch Q1 and the second switch Q2 to be turned on and off.

[0041] refer to Figure 4 , the first PWM drive signal and the second PWM drive signal of the first switch Q1 and the second switch Q2 of the DC-DC conversion module are generated by the intersection of the DC modulation wave Vref and the isosceles triangle carrier Vr1. The DC modulation wave Vref and the isosceles triangle carrier Vr1 intersect to obtain PWM pulse width signals: PWM1, PWM2, that is, the first PWM drive signal and the second PWM drive signal. When the DC modulation wave Vref is greater than or equal to the isosceles triangle carrier Vr1, PWM1 and PWM2 are high level, and when the DC modulation wave Vref is less than the isosceles triangle carrier Vr1, PWM1 and PWM2 are low level. Among them, VAB is the output voltage at both ends A and B of the DC / DC conversion unit 40 when each switch is turned on, and Vbus is the DC bus voltage.

[0042] Furthermore, the FPGA module integrates an overcurrent protection function. The FPGA module receives an overcurrent protection signal and performs an overcurrent protection action. Specifically, the FPGA module collects the overcurrent protection signal of the output current of the DC / DC conversion module. Once it detects that the output current exceeds the preset threshold, it determines that an overcurrent situation has occurred. At this time, the FPGA module will control the on and off of the first switch Q1 and the second switch Q2 of the DC / DC conversion module according to the internally set protection logic, and adjust the current in the circuit by changing the working state of the first switch Q1 and the second switch Q2, thereby achieving overcurrent protection and preventing the circuit from being damaged due to overcurrent.

[0043] In some specific embodiments of the present invention, the first switch Q1 includes a first switch tube and a ninth diode anti-parallel to the first switch tube, the first switch tube is a MOSFET tube (high-voltage metal oxide silicon field effect transistor), an IGBT tube (insulated gate bipolar transistor), an IGCT tube (integrated gate commutated thyristor) or an IEGT tube (enhanced injection gate transistor), the second switch Q2 includes a second switch tube and a tenth diode anti-parallel to the second switch tube, the second switch tube is a MOSFET tube (high-voltage metal oxide silicon field effect transistor), an IGBT tube (insulated gate bipolar transistor), an IGCT tube (integrated gate commutated thyristor) or an IEGT tube (enhanced injection gate transistor).

[0044] The ninth diode may be an independent diode or an anti-parallel diode inside the first switch tube. Accordingly, the drain or collector of the first switch tube is connected to the cathode of the ninth diode to form the first end of the first switch Q1, the source or emitter of the first switch tube is connected to the anode of the ninth diode to form the second end of the first switch Q1, and the gate or base of the first switch tube serves as the third end of the first switch Q1. The tenth diode may be an independent diode or an anti-parallel diode inside the second switch tube. Accordingly, the drain or collector of the second switch tube is connected to the cathode of the tenth diode to form the first end of the second switch Q2, the source or emitter of the second switch tube is connected to the anode of the tenth diode to form the second end of the second switch Q2, and the gate or base of the second switch tube serves as the third end of the second switch Q2.

[0045] In some embodiments, the present invention is not limited to the types of the first switch tube and the second switch tube, and they may be other types.

[0046] refer to Figure 2 In some specific embodiments of the present invention, the DC arc power supply circuit also includes a first filtering unit 30, the first filtering unit 30 includes a filtering capacitor C1, the first end of the filtering capacitor C1 is respectively connected to the rectifying unit 20 and the DC / DC conversion unit 40, and the second end of the filtering capacitor C1 is respectively connected to the rectifying unit 20 and the DC / DC conversion unit 40.

[0047] The voltage waveform of the DC power rectified by the rectifying unit 20 is not a stable straight line, but contains some AC ripple components. Through the characteristics of the filter capacitor C1 of "passing AC and blocking DC", the filter capacitor C1 can provide a low-impedance path for these AC ripple components, allowing the AC ripple current to flow into the filter capacitor C1 for storage and release, thereby effectively filtering out high-frequency ripples, making the output voltage smoother and closer to the ideal stable DC voltage, providing a better quality DC input for the subsequent DC / DC conversion module, and helping to improve the working performance of the DC / DC conversion module and the stability of the output voltage.

[0048] refer to Figure 2 In some specific embodiments of the present invention, the DC arc power supply circuit also includes a second filtering unit 60, the second filtering unit 60 includes a first inductor L1, a second inductor L2, a third inductor L3 and a fourth inductor L4, the first end of the first inductor L1 is connected to the DC / DC conversion unit 40, the second end of the first inductor L1 is respectively connected to the electrode unit 70 and the second end of the second inductor L2, the first end of the second inductor L2 is connected to the DC / DC conversion unit 40, the first end of the third inductor L3 is connected to the DC / DC conversion unit 40, the second end of the third inductor L3 is respectively connected to the electrode unit 70 and the second end of the fourth inductor L4, and the first end of the fourth inductor L4 is connected to the DC / DC conversion unit 40.

[0049] In this embodiment, the first inductor L1 and the second inductor L2 are connected to the positive output terminal of the DC / DC conversion unit 40, and the outputs of the first inductor L1 and the second inductor L2 are connected in parallel and then connected to the electrode unit 70, specifically, the positive graphite electrode connected to the electrode unit 70. The third inductor L3 and the fourth inductor L4 are connected to the negative output terminal of the DC / DC conversion unit 40, and the outputs of the third inductor L3 and the fourth inductor L4 are connected in parallel and then connected to the electrode unit 70, specifically, the negative graphite electrode connected to the electrode unit 70. The second filtering unit 60 is connected between the output terminals of the DC / DC conversion unit 40, and can be used to filter out high-frequency components in the output signal of the DC / DC conversion unit 40.

[0050] The embodiment of the present invention further provides a circuit board, comprising a DC arc power supply circuit as described in any of the above embodiments. The DC arc power supply circuit comprises a rectifier unit 20, a DC / DC conversion unit 40, an arc control unit 50 and an electrode unit 70, the rectifier unit 20 is connected to an external AC mains 10, the external AC mains 10 transmits AC power to the rectifier unit 20, the rectifier unit 20 rectifies the AC power into DC power and transmits the DC power to the DC / DC conversion unit 40, the arc control unit 50 sends a PWM signal to the DC / DC conversion unit 40, the DC / DC conversion unit 40 adjusts the DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit 70, so that the electrode unit 70 generates a DC arc. The DC arc power supply circuit generates a DC arc without the need for the current to cross the zero point, and is not easy to extinguish the arc, thereby being able to provide an arc with extremely high stability, so that the arc can be used for industrial applications such as metal welding and cutting.

[0051] An embodiment of the present invention also provides an electrical device, including the circuit board as described above. The circuit board includes a DC arc power supply circuit as described in any of the above embodiments. The DC arc power supply circuit includes a rectifier unit 20, a DC / DC conversion unit 40, an arc control unit 50 and an electrode unit 70, the rectifier unit 20 is connected to an external AC mains 10, the external AC mains 10 transmits AC power to the rectifier unit 20, the rectifier unit 20 rectifies AC power into DC power and transmits DC power to the DC / DC conversion unit 40, the arc control unit 50 sends a PWM signal to the DC / DC conversion unit 40, the DC / DC conversion unit 40 adjusts DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit 70, so that the electrode unit 70 generates a DC arc. The DC arc power supply circuit generates a DC arc without the need for current zero crossing, and is not easy to extinguish the arc, thereby being able to provide an arc with extremely high stability, so that the arc can be used for industrial applications such as metal welding and cutting.

[0052] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0053] The above-described embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the present invention. It should be pointed out that, for a person of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. A DC arc power supply circuit, characterized in that: The DC arc power supply circuit includes a rectifier unit, a DC / DC conversion unit, an arc control unit and an electrode unit. The rectifier unit is connected to an external AC mains, and the external AC mains transmits AC power to the rectifier unit. The rectifier unit rectifies the AC power into DC power and transmits the DC power to the DC / DC conversion unit. The arc control unit sends a PWM signal to the DC / DC conversion unit. The DC / DC conversion unit adjusts the DC power according to the PWM signal and transmits the adjusted DC power to the electrode unit, so that the electrode unit generates a DC arc.

2. The DC arc power supply circuit according to claim 1, characterized in that: The rectifier unit includes a first group of diodes, a second group of diodes and a third group of diodes. The first group of diodes includes a first diode and a second diode. Phase A of the external AC mains is connected to the positive electrode of the first diode and the negative electrode of the second diode. The negative electrode of the first diode is connected to the DC / DC conversion unit, and the positive electrode of the second diode is connected to the DC / DC conversion unit. The second group of diodes includes a third diode and a fourth diode. Phase B of the external AC mains is connected to the positive electrode of the third diode and the negative electrode of the fourth diode. The negative electrode of the third diode is connected to the DC / DC conversion unit, and the positive electrode of the fourth diode is connected to the DC / DC conversion unit. The third group of diodes includes a fifth diode and a sixth diode. Phase C of the external AC mains is connected to the positive electrode of the fifth diode and the negative electrode of the sixth diode. The negative electrode of the fifth diode is connected to the DC / DC conversion unit, and the positive electrode of the sixth diode is connected to the DC / DC conversion unit.

3. The DC arc power supply circuit according to claim 1, characterized in that: The DC / DC conversion unit includes a first bridge arm topology module and a second bridge arm topology module, the first bridge arm topology module includes a first switch and a seventh diode, the first end of the first switch is connected to the rectifier unit, the second end of the first switch is respectively connected to the cathode of the seventh diode and the electrode unit, the third end of the first switch is connected to the arc control unit, and the anode of the seventh diode is respectively connected to the rectifier unit and the electrode unit, the second bridge arm topology module includes a second switch and an eighth diode, the first end of the second switch is connected to the rectifier unit, the second end of the second switch is respectively connected to the cathode of the eighth diode and the electrode unit, the third end of the second switch is connected to the arc control unit, and the anode of the eighth diode is respectively connected to the rectifier unit and the electrode unit.

4. The DC arc power supply circuit according to claim 3, characterized in that: The arc control unit includes an arc control module, a current sampling module and a voltage sampling module. The current sampling module is connected to the arc control module and the DC / DC conversion unit. The voltage sampling module is connected to the arc control module and the DC / DC conversion unit. The current sampling module collects the output current of the DC / DC conversion unit and sends the output current to the arc control module. The voltage sampling module collects the output voltage of the DC / DC conversion unit and sends the output voltage to the arc control module. The arc control module calculates the first PWM drive signal and the second PWM drive signal according to the output current and the output voltage through a PID algorithm, and sends the first PWM drive signal and the second PWM drive signal to the first switch and the second switch.

5. The DC arc power supply circuit according to claim 4, characterized in that: The arc control module includes a DSP module and an FPGA module, the DSP module is connected to the FPGA module, the current sampling module collects the output current of the DC / DC conversion unit and sends the output current to the DSP module, the voltage sampling module collects the output voltage of the DC / DC conversion unit and sends the output voltage to the DSP module, the DSP module calculates the first PWM control signal and the second PWM control signal according to the output current and the output voltage through a PID algorithm, and sends the first PWM control signal and the second PWM control signal to the FPGA module, the FPGA module converts the first PWM control signal and the second PWM control signal into a first PWM drive signal and a second PWM drive signal, and sends the first PWM drive signal and the second PWM drive signal to the first switch and the second switch.

6. The DC arc power supply circuit according to claim 3, characterized in that: The first switch includes a first switch tube and a ninth diode anti-parallel to the first switch tube, the first switch tube is a MOSFET tube, an IGBT tube, an IGCT tube or an IEGT tube, the second switch includes a second switch tube and a tenth diode anti-parallel to the second switch tube, the second switch tube is a MOSFET tube, an IGBT tube, an IGCT tube or an IEGT tube.

7. The DC arc power supply circuit according to claim 1, characterized in that: The DC arc power supply circuit also includes a first filtering unit, which includes a filtering capacitor, wherein the first end of the filtering capacitor is respectively connected to the rectifying unit and the DC / DC conversion unit, and the second end of the filtering capacitor is respectively connected to the rectifying unit and the DC / DC conversion unit.

8. The DC arc power supply circuit according to claim 1, characterized in that: The DC arc power supply circuit also includes a second filtering unit, which includes a first inductor, a second inductor, a third inductor and a fourth inductor, wherein a first end of the first inductor is connected to the DC / DC conversion unit, a second end of the first inductor is respectively connected to the electrode unit and the second end of the second inductor, a first end of the second inductor is connected to the DC / DC conversion unit, a first end of the third inductor is connected to the DC / DC conversion unit, a second end of the third inductor is respectively connected to the electrode unit and the second end of the fourth inductor, and a first end of the fourth inductor is connected to the DC / DC conversion unit.

9. A circuit board, characterized in that: Comprising a DC arc power supply circuit as described in any one of claims 1 to 8.

10. An electrical device, characterized in that: Comprising the circuit board as claimed in claim 9.

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