Welding machine driving circuit with charging function and electric welding machine

Abstract

The utility model relates to welding equipment technical field discloses a welding machine drive circuit and electric welding machine with charging function. The welding machine drive circuit contains active rectifier chopper circuit, power factor correction circuit, charging circuit and power -on soft start circuit. Active rectifier chopper circuit utilizes MOS tube low conduction impedance characteristic to reduce on -voltage drop loss, power factor correction circuit adopts BOOST boost topology structure, and optimization input current waveform, and inhibits harmonic interference, and charging circuit realizes high -efficient energy transmission through half -bridge inverter and high -frequency isolation design, and power -on soft start circuit combines current -limiting resistance and relay, and protects circuit element from impact damage. The scheme realizes the efficient cooperation of welding and charging function while simplifying system architecture.

Description

Technical Field

[0001] This utility model relates to the field of welding equipment technology, and discloses a welding machine drive circuit with charging function and an electric welding machine. Background Technology

[0002] Existing lithium-ion battery welding machines typically employ diode-based freewheeling chopper circuits and bridge rectifier-filter charging structures. The high forward voltage drop of the diodes in the chopper circuit leads to significant energy loss, requiring large heat sinks, increasing costs, and reducing overall efficiency. Direct rectification of mains power in the charging circuit generates large current surges and high harmonic content in the input current, polluting the power grid and causing poor electromagnetic compatibility. Furthermore, traditional designs lack soft-start mechanisms, making components susceptible to damage from instantaneous current peaks during capacitor charging. The root cause of these problems lies in the improper selection of freewheeling components and the lack of power factor correction functionality in the pre-charging stage, hindering improvements in equipment energy efficiency and reliability. Summary of the Invention

[0003] To address the aforementioned technical shortcomings, the purpose of this utility model is to provide a welding machine drive circuit and welding machine with charging function, thereby solving the problems of low welding machine efficiency, large charging harmonics, and current surges in the existing technology.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] In a first aspect, this utility model provides a welding machine drive circuit with a charging function, the circuit comprising:

[0006] An active rectifier chopper circuit is connected to an AC power supply at its input terminal. It consists of a first MOSFET, a second MOSFET, and a first inductor. The sources of the first MOSFET and the second MOSFET are connected together and connected to one end of the first inductor.

[0007] The power factor correction circuit is connected to the active rectifier chopper circuit, including a rectifier bridge, a third MOSFET, a fast recovery diode, a second inductor, and an output capacitor. The AC side of the rectifier bridge is connected to the AC power supply, and the DC side is connected to the drain of the third MOSFET through the second inductor. The anode of the fast recovery diode is connected to the source of the third MOSFET, and the cathode is connected to the output capacitor.

[0008] The charging circuit, connected to the power factor correction circuit, includes a half-bridge inverter unit, a high-frequency transformer, a rectifier unit, and a filter inductor. The two ends of the half-bridge inverter unit are connected to the output capacitor of the power factor correction circuit, and the output end is connected to the rectifier unit through the high-frequency transformer. The output of the rectifier unit forms a charging port through the filter inductor.

[0009] The power-on soft-start circuit is connected between the AC power supply and the power factor correction circuit. It includes a current-limiting resistor and a relay connected in series. The relay is connected in parallel across the current-limiting resistor to achieve power-on buffer control.

[0010] Preferably, in one possible implementation of the first aspect, in the active rectifier chopper circuit, the drive signals of the first MOSFET and the second MOSFET are complementary and have a dead time, and the current of the first inductor freewheels through the body diode of the second MOSFET during the dead time.

[0011] Preferably, in one possible implementation of the first aspect, the power factor correction circuit is a BOOST topology.

[0012] Preferably, in one possible implementation of the first aspect, the negative terminal of the output capacitor is connected to the negative DC terminal of the rectifier bridge.

[0013] Preferably, in one possible implementation of the first aspect, the half-bridge inverter unit of the charging circuit is composed of two IGBT transistors connected in series, and the primary side of the high-frequency transformer is connected between the midpoint of the two IGBT transistors and the midpoint of the output capacitor.

[0014] Preferably, in one possible implementation of the first aspect, the rectifier unit consists of a full-bridge rectifier structure composed of four Schottky diodes, and the input terminal of the filter inductor is connected to the output terminal of the full-bridge rectifier structure.

[0015] Preferably, in one possible implementation of the first aspect, the resistance value of the current-limiting resistor is configured to suppress the instantaneous current peak during capacitor charging.

[0016] Secondly, this utility model provides a welding machine with a charging function, including the welding machine drive circuit of the first aspect, as well as a welding actuator and a lithium battery pack connected to the output end of the drive circuit.

[0017] The beneficial effects of this invention are as follows: Through a complementary-driven active rectifier-chopper circuit, low-loss freewheeling is achieved using MOSFET body diodes, significantly reducing on-state voltage drop and heat loss, improving energy conversion efficiency while reducing heat dissipation requirements. The power factor correction circuit optimizes the input current waveform, effectively suppressing harmonic interference and improving grid compatibility. The soft-start mechanism, combined with current-limiting resistors and relays for coordinated control, smoothly transitions the capacitor charging process during power-on, protecting circuit components from impact damage. The half-bridge inverter and high-frequency isolation design achieves efficient energy transfer in the charging circuit, while the full-bridge rectifier structure ensures the stability and safety of battery charging.

[0018] The overall solution simplifies the system architecture while achieving efficient coordination between welding and charging functions. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This application provides a structural diagram of a welding machine drive circuit with charging function.

[0021] Figure 2 This application provides a structural diagram of a welding machine with a charging function. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0023] Example 1: As Figure 1 As shown, this utility model provides a welding machine drive circuit with charging function. The circuit includes an active rectifier chopper circuit, a power factor correction circuit, a charging circuit, and a power-on soft start circuit.

[0024] An active rectifier chopper circuit is connected to an AC power supply at its input terminal. It consists of a first MOSFET, a second MOSFET, and a first inductor. The sources of the first MOSFET and the second MOSFET are connected together and connected to one end of the first inductor.

[0025] In this embodiment, the active rectifier chopper circuit adopts a dual MOSFET collaborative control architecture. The source interconnects of the first MOSFET (Q4N) and the second MOSFET (Q5N) form a common node, which is connected to the subsequent circuit through the first inductor (L3). The gates of the two MOSFETs receive complementary phase drive signals, and a preset dead time is provided between the two drive signals. When the first MOSFET is turned on, the second MOSFET is turned off, and the AC power supply forms a forward current path through the first MOSFET and the first inductor; when the second MOSFET is turned on, the first MOSFET is turned off, and the current path switches to the loop formed by the second MOSFET and the first inductor.

[0026] During the dead time period of alternating drive signal transitions, the magnetic energy stored in the first inductor forms a freewheeling path through the body diode integrated inside the second MOSFET, enabling continuous current transfer. This structure replaces the traditional diode freewheeling method with the low on-resistance characteristic of the MOSFET, reducing on-state voltage drop losses. At the same time, it utilizes the natural freewheeling characteristic of the body diode to ensure no current interruption during commutation, improving overall system efficiency while avoiding the additional heat dissipation requirements of discrete freewheeling diodes.

[0027] The power factor correction circuit is connected to the active rectifier chopper circuit and includes a rectifier bridge, a third MOSFET, a fast recovery diode, a second inductor, and an output capacitor. The AC side of the rectifier bridge is connected to the AC power supply, and the DC side is connected to the drain of the third MOSFET through the second inductor. The anode of the fast recovery diode is connected to the source of the third MOSFET, and the cathode is connected to the output capacitor.

[0028] In this embodiment, the power factor correction circuit adopts a BOOST boost topology to achieve active power factor correction. The AC input terminal of the rectifier bridge (BD1) is directly connected to the AC power supply, converting the input 220V / 50Hz AC power into pulsating DC power. The positive terminal of the rectifier bridge's DC output is connected to the drain of the third MOSFET (Q1) through the second inductor (L1), forming the core energy transfer path of the BOOST boost main circuit. The source of the third MOSFET is connected to the anode of the fast recovery diode (D3), and the cathode of the fast recovery diode is connected across the positive terminal of the output capacitor (EC1), forming the current freewheeling path of the boost circuit. The negative terminal of the output capacitor (EC1) is directly connected to the negative terminal of the DC output of the rectifier bridge (BD1) through a low-impedance wire, constructing a complete current loop.

[0029] When the third MOSFET (Q1) is periodically turned on under the control of the drive signal, the second inductor (L1) begins to store energy. At this time, the fast recovery diode (D3) is turned off due to reverse voltage, and the output capacitor (EC1) supplies power to the subsequent circuit. When Q1 is turned off, the magnetic energy stored in L1 is released to EC1 through the fast recovery diode (D3), causing the output voltage to rise to the set value. This boost process adjusts the duty cycle of Q1 through a PWM control strategy, so that the input current waveform tracks the input voltage waveform in real time.

[0030] The charging circuit, connected to the power factor correction circuit, includes a half-bridge inverter unit, a high-frequency transformer, a rectifier unit, and a filter inductor. The two ends of the half-bridge inverter unit are connected to the output capacitor of the power factor correction circuit, and the output end is connected to the rectifier unit through the high-frequency transformer. The output of the rectifier unit forms the charging port through the filter inductor.

[0031] In this embodiment, the charging circuit uses a half-bridge inverter unit to achieve DC-AC conversion. This unit consists of two IGBT transistors (Q2N and Q3N) connected in series, with their collectors and emitters connected across the positive and negative terminals of the output capacitor (EC1) of the power factor correction circuit, respectively. One end of the primary winding of the high-frequency transformer (T1) is connected to the midpoint of the two IGBT transistors, and the other end is directly coupled to the voltage midpoint of the output capacitor (EC1) through a low-inductance wire, forming a symmetrical magnetic flux path. When Q2N and Q3N are alternately turned on under the control of complementary PWM drive signals, the DC energy stored in EC1 is converted into high-frequency square wave AC power, and electrical isolation and voltage regulation are achieved through T1.

[0032] The secondary winding of the high-frequency transformer (T1) is connected to a full-bridge rectifier unit consisting of four Schottky diodes (D5-D8). The anodes of D5 and D6 are connected together to form the negative rectifier terminal, while the cathodes of D7 and D8 are connected together to form the positive rectifier terminal. This topology utilizes the low forward voltage drop and fast recovery characteristics of Schottky diodes to effectively reduce rectification losses and suppress reverse recovery current. The pulsating DC output from the rectifier unit is smoothed by a filter inductor (L2), ultimately forming a stable DC charging voltage at the charging ports (BAT+, BAT-).

[0033] The power-on soft-start circuit is connected between the AC power supply and the power factor correction circuit. It includes a current-limiting resistor and a relay connected in series, with the relay connected in parallel across the current-limiting resistor to achieve power-on buffer control.

[0034] In this embodiment, the power-on soft-start circuit consists of a hardware buffer control loop formed by a current-limiting resistor R9 and a relay K1. Specifically, the current-limiting resistor R9 is a 5W / 10W resistor. The metal oxide film resistor, whose resistance value is determined by calculating the charging time constant of capacitor EC1 and the maximum allowable inrush current, can effectively limit the peak surge current at power-on to within 15A. Relay K1 is a 30A double-contact electromagnetic relay, whose coil drive terminal is connected to the delayed trigger signal output port of the control system.

[0035] When AC power is first connected, relay K1 is in the normally open state, and the AC input current must flow through the current-limiting resistor R9 into the power factor correction circuit. At this time, R9 acts as a current-limiting element to suppress the transient large current generated by the charging of capacitor EC1, preventing damage to rectifier bridge BD1 and MOSFET Q1 due to overcurrent surges. After the control system detects that the input voltage has stabilized, it sends a closing command to relay K1 after a 200ms delay, causing the relay contacts to close and form a low-impedance path, bypassing the current-limiting resistor R9. This delay parameter is set according to the time it takes for EC1 to charge to 80% of its rated voltage, ensuring that the relay operates after the capacitor pre-charging is complete, achieving a smooth transition to normal operating conditions.

[0036] Example 2: Figure 2 As shown, this utility model provides a welding machine with a charging function, including a welding machine drive circuit, a welding actuator and a lithium battery pack connected to the output end of the drive circuit. The welding actuator consists of a welding torch, an arc control module and a current feedback unit, and drives the generation of a welding arc through the DC bus voltage output by the power factor correction circuit; the lithium battery pack is electrically connected to the output end of the filter inductor through a charging port, and realizes energy storage through a half-bridge inverter unit and a high-frequency transformer.

[0037] In practice, the lithium battery pack is composed of multiple 18650 lithium-ion batteries connected in series and parallel, with their positive and negative terminals connected to the BAT+ and BAT- terminals of the charging port, respectively. The arc control module of the welding actuator has a built-in PWM modulation unit, which dynamically adjusts the drive duty cycle of the first and second MOSFETs in the active rectifier chopper circuit by acquiring the welding current signal, thereby achieving precise control of the welding current. The relay control signal of the soft-start circuit is triggered by the voltage detection unit of the lithium battery pack. When the voltage across the output capacitor of the power factor correction circuit reaches the threshold, the relay is driven to close to bypass the current-limiting resistor.

[0038] The welding machine's internal casing features a layered layout, with the power factor correction circuit and half-bridge inverter unit housed in independent heat dissipation chambers and electrically connected via copper busbars. The high-frequency transformer is encapsulated in epoxy resin and integrated with the rectifier unit within an electromagnetic shielding enclosure, effectively suppressing high-frequency interference. During operation, the AC power supply undergoes active rectification, chopping, and power factor correction to form a stable DC output. Simultaneously, the charging circuit efficiently charges the lithium battery pack. Welding and charging functions are switched collaboratively via a bus controller.

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

Claims

1. A welding machine drive circuit with charging function, characterized in that, The circuit includes: An active rectifier chopper circuit is connected to an AC power supply at its input terminal. It consists of a first MOSFET, a second MOSFET, and a first inductor. The sources of the first MOSFET and the second MOSFET are connected together and connected to one end of the first inductor. The power factor correction circuit is connected to the active rectifier chopper circuit, including a rectifier bridge, a third MOSFET, a fast recovery diode, a second inductor, and an output capacitor. The AC side of the rectifier bridge is connected to the AC power supply, and the DC side is connected to the drain of the third MOSFET through the second inductor. The anode of the fast recovery diode is connected to the source of the third MOSFET, and the cathode is connected to the output capacitor. The charging circuit, connected to the power factor correction circuit, includes a half-bridge inverter unit, a high-frequency transformer, a rectifier unit, and a filter inductor. The two ends of the half-bridge inverter unit are connected to the output capacitor of the power factor correction circuit, and the output end is connected to the rectifier unit through the high-frequency transformer. The output of the rectifier unit forms a charging port through the filter inductor. The power-on soft-start circuit is connected between the AC power supply and the power factor correction circuit. It includes a current-limiting resistor and a relay connected in series. The relay is connected in parallel across the current-limiting resistor to achieve power-on buffer control.

2. The welding machine drive circuit with charging function according to claim 1, characterized in that, In the active rectifier chopper circuit, the drive signals of the first MOSFET and the second MOSFET are complementary and have a dead time. During the dead time, the current of the first inductor freewheels through the body diode of the second MOSFET.

3. The welding machine drive circuit with charging function according to claim 1, characterized in that, The power factor correction circuit is a BOOST boost topology.

4. The welding machine drive circuit with charging function according to claim 3, characterized in that, The negative terminal of the output capacitor is connected to the negative DC terminal of the rectifier bridge.

5. The welding machine drive circuit with charging function according to claim 1, characterized in that, The half-bridge inverter unit of the charging circuit consists of two IGBT transistors connected in series, and the primary side of the high-frequency transformer is connected between the midpoint of the two IGBT transistors and the midpoint of the output capacitor.

6. The welding machine drive circuit with charging function according to claim 5, characterized in that, The rectifier unit consists of a full-bridge rectifier structure composed of four Schottky diodes, and the input terminal of the filter inductor is connected to the output terminal of the full-bridge rectifier structure.

7. The welding machine drive circuit with charging function according to claim 1, characterized in that, The resistance value of the current-limiting resistor is configured to suppress the instantaneous current peak during capacitor charging.

8. A welding machine with a charging function, characterized in that, It includes the welding machine drive circuit as described in any one of claims 1-7, as well as the welding actuator and lithium battery pack connected to the output of the drive circuit.

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