Battery capacity-increasing ultra-wide voltage output high-power electric fusion welding machine with multi-source combined power supply

Abstract

The invention relates to a multi-source combined power supply battery capacity-increasing ultra-wide voltage output high-power electric fusion welding machine, which adopts a two-split type plug-in mounting combined structure and comprises a battery power supply split device and a power grid power supply split device, the battery power supply split device comprises a battery power supply unit shell, a computer control unit, a power voltage adjusting unit, an external battery pack and a DCDC converter; a plurality of groups of battery sockets are transversely arranged at the upper part of the front side of the battery power supply unit shell, a welding machine output interface is arranged at one side of the battery power supply unit shell, and a battery unit to power grid unit butt joint interface is arranged at the rear side of the battery power supply unit shell; the computer control unit, the power voltage adjusting unit and the DCDC converter are arranged in a shell of the battery power supply unit; the power grid power supply split device comprises a power grid power supply unit shell, a control unit and a circuit unit; a power input socket is arranged on the top or the side portion of the power grid power supply unit shell, and a power grid unit to battery unit butt joint interface is arranged on the front side of the power grid power supply unit shell. According to the invention, multi-source combined power supply is realized.

Description

Technical Field

[0001] The invention belongs to the technical field of plastic electric fusion pipe connection construction equipment, and in particular relates to a multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine. Background Art

[0002] The electric fusion connection is to put the electric fusion pipe fittings on the pipes and pipe fittings, and the resistance wire embedded in the inner surface of the electric fusion pipe fittings is energized to generate heat. The heat energy generated heats and melts the inner surface of the electric fusion pipe fittings and the outer surface of the pipe that bears the difference, making them merge into one. The electric fusion connection is one of the most important connection methods for polyethylene pipes.

[0003] The first patent for electrofusion connection was obtained in 1954, but it was not until 1975 that the electrofusion pipe manufacturing line designed by GeorgFisher of Switzerland for gas systems appeared. In the 1970s, polyethylene gas pipes began to be used on a large scale in some European countries, such as Belgium, France and the United Kingdom. These pipelines were buried underground, which put forward higher requirements for electrofusion connection. Since then, the research and development of electrofusion connection has developed rapidly, and a large number of patents have emerged, covering all aspects of the design, manufacture and use of electrofusion pipe fittings.

[0004] The advantage of electrofusion connection is that it can greatly reduce the influence of human factors in the welding process. The influence of welding machine process parameters - temperature and pressure on the quality of the joint is crucial, and electrofusion connection can obtain high-quality joints - high strength, long life, good airtightness, and easy operation and high construction efficiency through the structural design of pipe fittings and precise control of input power (optimization of operating voltage or current and power-on time). The main disadvantage of the electrofusion connection method is its high cost.

[0005] Electric fusion connection has been widely used in polyethylene gas pipeline systems. With the rapid development of polyethylene water supply pipes, electric fusion connection is also widely used in polyethylene water supply pipe systems. In addition, electric fusion connection can also be used for the connection of polypropylene pipes, polybutylene pipes, etc.

[0006] The electric fusion connection is realized by electric fusion pipe fittings. Figure 1 is the structural diagram of the sleeve type electric fusion pipe fittings. The polyethylene sleeve part with a heating resistance wire on the inner surface converts the provided electrical energy into heat energy through the heating resistance wire, and the inner surface of the sleeve and the outer surface of the inserted pipe are melted to achieve the connection. The device that provides electrical energy for the pipe resistance wire is the electric fusion welding machine. With the development of electric fusion connection technology, higher and higher requirements are put forward for electric fusion welding machines.

[0007] The current fully automatic electric fusion welding machine has the following problems in actual use:

[0008] 1. Poor electromagnetic compatibility. Electromagnetic compatibility is electromagnetic interference. Traditional electric fusion welding machines are powered by 220V power frequency voltage and adopt high-frequency switching structure, which will produce certain interference. Interference is divided into conduction and radiation. Conduction will cause great pollution to the power grid, and radiation will interfere with surrounding electrical appliances.

[0009] 2. Inconvenient to use in the field. It needs power supply from the grid. It is inconvenient to pull power lines in the field. The configuration of generators will increase various costs.

[0010] 3. Poor explosion-proof safety. Due to the connection with the power grid, it is not suitable for explosion-proof applications;

[0011] 4. The existing built-in series lithium battery step-down output solution has the following disadvantages:

[0012] (1) The battery capacity is limited, and the number of welding times per charge is insufficient;

[0013] (2) The battery power is limited, the output current is insufficient, and the welding machine has insufficient capacity for large-diameter pipes;

[0014] (3) Using a step-down DC-DC converter, in order to meet the standard output voltage of 39.5V, only a high-voltage lithium battery with a nominal voltage of more than 48V can be used for power supply, which places high demands on the power supply battery. For higher voltage electric fusion pipe fittings (such as DC80V8KVA pipe fittings), it is extremely difficult to match such a high-voltage and high-power battery. Summary of the invention

[0015] In view of the above technical problems, the present invention provides a multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine.

[0016] One of the above-mentioned purposes of the present invention is achieved by the following technical solution:

[0017] A multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine, the electric fusion welding machine adopts a two-split plug-in combination structure, including a battery power supply split device and a power grid power supply split device;

[0018] The battery-powered split device includes a battery-powered unit housing, a computer control unit, a power voltage adjustment unit, an external battery pack, and a DCDC converter;

[0019] A plurality of battery sockets are arranged horizontally on the upper front side of the battery power supply unit housing for plugging in an external battery pack; a welding machine output interface is arranged on the left or right side of the battery power supply unit housing, and a welding machine battery power supply unit working status indicator light is arranged on the same side as the welding machine output interface; a battery unit to power grid unit docking interface is arranged on the rear side of the battery power supply unit housing; the external battery pack is plugged and connected to the battery socket on the battery power supply unit housing;

[0020] The computer control unit, power voltage adjustment unit and DCDC converter are installed in the housing of the battery power supply unit; the computer control unit is responsible for Bluetooth communication with the mobile phone; the power voltage adjustment unit is used to output and collect various machine signals, and is responsible for allocating and combining power supply from the power grid and power supply from the battery, realizing a separate power supply mode of the two power supply modes or a series power supply mode or a parallel power supply mode of the two power supply modes, and adjusting the output voltage of the welding machine to a constant welding machine voltage value; the DCDC converter is used to convert the direct current input from the external battery pack to meet the output requirements of the electric fusion welding machine;

[0021] The grid power supply split device comprises a grid power supply unit housing, a control unit and a circuit unit;

[0022] A power input socket is provided on the top or side of the power supply unit housing for connecting 220V or 380V AC power. A power supply unit to battery unit docking interface is provided on the front side of the power supply unit housing. The power supply unit to battery unit docking interface corresponds to the battery unit to power supply unit docking interface. By plugging and matching the two, power supply of the welding machine to the power supply unit and / or battery charging can be realized.

[0023] The control unit and the circuit unit are installed in the housing of the power supply unit. The circuit unit is used to rectify and filter the input power supply of the ...

[0024] Moreover, the battery power supply unit shell adopts a fully enclosed aluminum alloy box-shaped shell; a heat dissipation fin structure is adopted at the front lower part of the battery power supply unit shell; a handle is arranged at the top of the battery power supply unit shell; the grid power supply unit shell adopts a fully enclosed aluminum alloy box-shaped shell, a heat dissipation fin structure is adopted at the entire rear part of the grid power supply unit shell, and a handle is also arranged at the top of the grid power supply unit shell.

[0025] Moreover, the power voltage adjustment unit includes a first contact switch K1, a second contact switch K2, a third contact switch K3, a fourth contact switch K4, a fifth contact switch K5, and a sixth contact switch K6; the third contact switch K3 and the sixth contact switch K6 are successively connected in series on a first line connecting the positive output end of the power grid and the positive pole of the welding machine output interface, the fifth contact switch K5 is connected in series on a second line connecting the negative output end of the power grid and the negative pole of the welding machine output interface, a third line is connected between the positive output end of the DCDC converter and the first line, a contact point between the third line and the first line is located between the third contact switch K3 and the sixth contact switch K6, and a second contact switch K3 is connected in series on the third line. switch K2; the negative output terminal of the DCDC converter is respectively connected to the front end position and the rear end position of the second circuit where the fifth contact switch K5 is installed through the fourth circuit and the fifth circuit connected in parallel, the first contact switch K1 is connected in series on the fourth circuit, the sixth circuit is connected between the front end of the third circuit where the second contact switch K2 is installed and the rear end of the fourth circuit where the first contact switch K1 is installed, and the fourth contact switch K4 is installed in series on the sixth circuit; the seventh circuit is connected between the positive output terminal of the external battery pack and the positive output terminal of the power grid, the eighth circuit is connected between the negative output terminal of the external battery pack and the negative output terminal of the power grid, and the seventh circuit and the eighth circuit are respectively installed in series with the seventh contact switch K7 and the eighth contact switch K8;

[0026] When K1, K2, K5, K7 and K8 are all in the open state, and K3, K4 and K6 are all in the closed state, the electric fusion welding machine is in a power supply mode of a combination of a power grid and a battery in series;

[0027] When K1, K4, K7 and K8 are all in the open state, K2, K3, K5 and K6 are all in the closed state, the electric fusion welding machine is in the parallel combination power supply mode;

[0028] When K1, K2, K4, K7 and K8 are all in the open state, K3, K5 and K6 are all in the closed state, the electric fusion welding machine is in the grid power supply mode;

[0029] When K1, K3, K4, K5, K7 and K8 are all in the open state, K2 and K6 are all in the closed state, the electric fusion welding machine is in the battery-powered mode;

[0030] When K1, K2, K3, K4, K5, and K6 are all in the open state, and K7 and K8 are all in the closed state, the electric fusion welding machine is in the battery charging mode.

[0031] The present invention has the following advantages and positive effects:

[0032] The present invention has complete functions of a fully automatic electric fusion welding machine. The welding machine parameters can be manually set to output an adjustable constant true effective value voltage. The mobile phone can also be connected via Bluetooth to identify the standard welding machine barcode and automatically output the welding machine. In addition, it has multiple modes of power supply. First, a detachable multi-interface lithium battery can be connected to power the welding machine. The welding machine has an adjustment circuit inside, which can adjust the voltage of the lithium battery to a constant voltage required for the electric fusion connection of the polyethylene pipe. Second, it has a multi-battery series-parallel capacity expansion function. The welding machine has multiple external battery sockets. When the capacity of a single external battery is insufficient, multiple lithium batteries can be plugged in for parallel capacity expansion. Third, it has a traditional 220V or 380V AC power grid welding machine and an online charging function for the battery. Fourth, the power grid power supply and the battery power supply are switched through circuits to realize series or parallel power supply, thereby realizing power capacity expansion), and doubling the output power of the welding machine and doubling the output voltage range without introducing other resources.

[0033] The advantages and positive effects of the present invention are:

[0034] Compared with the prior art, the present invention has the following advantages:

[0035] 1. Multi-source combined power supply system: The electric fusion welding machine of the present invention has three power supply modes: grid power supply, battery power supply, and grid + battery series-parallel combination power supply.

[0036] 2. Ultra-wide voltage and ultra-large power output: The output voltage range of the electric fusion welding machine of the present invention is DC8-80V, which is much wider than the existing welding machine level of 8-48V; the maximum power can reach 80KVA, which is much larger than the existing common welding machines within 4KVA.

[0037] 3. Implement a multi-mode power supply combination strategy, which can be adjusted to the optimal power supply strategy in various power supply scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1a It is a schematic diagram of the electric fusion welding machine of the present invention in a first angle in an assembled state;

[0039] Figure 1b It is a second angle schematic diagram of the electric fusion welding machine of the present invention in the assembled state;

[0040] Figure 2a It is a schematic diagram of the electric fusion welding machine of the present invention in a separated state from a first angle;

[0041] Figure 2b It is a second angle schematic diagram of the electric fusion welding machine of the present invention in a separated state;

[0042] Figure 3 It is a welding machine working system diagram of the electric fusion welding machine of the present invention in the combined power supply mode;

[0043] Figure 4 It is a welding machine working system diagram of the electric fusion welding machine of the present invention in a battery-powered mode;

[0044] Figure 5 It is a working principle diagram of the electric fusion welding machine of the present invention in a series combination power supply mode;

[0045] Figure 6 It is a working principle diagram of the electric fusion welding machine of the present invention in a parallel combination power supply mode;

[0046] Figure 7 It is a working principle diagram of the electric fusion welding machine of the present invention in the power grid power supply mode;

[0047] Figure 8 It is a working principle diagram of the electric fusion welding machine of the present invention in a battery-powered mode;

[0048] Fig. 9 It is a schematic diagram of the connection between the power voltage adjustment unit of the present invention and the power grid and the battery pack;

[0049] Fig.10 It is a flow chart of the power supply strategy of the electric fusion welding machine of the present invention. DETAILED DESCRIPTION

[0050] The structure of the present invention is further described below with reference to the accompanying drawings and by way of examples. It should be noted that the present examples are descriptive rather than restrictive.

[0051] A multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine, see Figure 1- Fig.10 The invention point is: the electric fusion welding machine adopts a two-split plug-in combination structure, including a battery-powered split device 1 and a grid-powered split device 2.

[0052] The battery-powered split device comprises a battery-powered unit housing 1.1, a computer control unit, a power voltage adjustment unit, an external battery pack 1.2, and a DCDC converter.

[0053] The battery power supply unit shell adopts a fully enclosed box-shaped shell, and the shell material is aluminum alloy, which plays a role in increasing the protection level and avoiding electromagnetic radiation. A heat dissipation fin structure 1.3 is adopted at the lower front side of the battery power supply unit shell, and a heat dissipation fan can also be added to force air cooling and heat dissipation. A plurality of battery sockets are arranged laterally on the upper front side of the battery power supply unit shell for plugging in external battery packs. A welding machine output interface 1.4 is arranged on the left or right side of the battery power supply unit shell, and a welding machine battery power supply unit working status indicator light is arranged on the same side as the welding machine output interface. A battery unit to power grid unit docking interface 1.6 is arranged on the rear side of the battery power supply unit shell. A handle 1.5 is arranged on the top of the battery power supply unit shell, which is usually used as a handle and can also be used to store and wrap input and output cables.

[0054] The external battery pack is used to realize external battery power supply and is plugged into and connected with the battery socket on the housing of the battery power supply unit.

[0055] The computer control unit, power voltage adjustment unit and DCDC converter are installed in the battery power supply unit housing. The computer control unit is responsible for Bluetooth communication with the mobile phone. The power voltage adjustment unit is used to output and collect various signals inside the machine, and is responsible for allocating and combining power supply from the power grid and battery power supply, and adjusting the output voltage of the welding machine to a constant welding machine voltage value. The DCDC converter is used to convert the direct current input from the external battery pack to meet the output requirements of the electric fusion welding machine.

[0056] The grid power supply split device comprises a grid power supply unit housing 2.2, a control unit and a circuit unit.

[0057] The power grid power supply unit shell adopts a fully enclosed box-shaped shell, and the shell material is aluminum alloy, which plays a role in increasing the protection level and avoiding electromagnetic radiation. The entire rear part of the power grid power supply unit shell adopts a heat dissipation fin structure 2.3, and a heat dissipation fan can also be added to force air cooling and heat dissipation. A power input socket 2.4 is arranged on the top or side of the power grid power supply unit shell, which is used to connect AC 220V or 380V, and can be used for online charging and "power grid + battery" mode power supply. A handle 2.1 is also arranged on the top of the power grid power supply unit shell. The handle is usually used as a handle and can also be used to store and wrap input and output cables. A power grid unit to battery unit docking interface 2.5 is arranged on the front side of the power grid power supply unit shell. The power grid unit battery unit docking interface corresponds to the battery unit to power grid unit docking interface. Through the plug-in cooperation of the two, the power grid power supply or battery charging of the welding machine can be realized.

[0058] The control unit and the circuit unit are installed in the housing of the grid power supply unit. The circuit unit is used to rectify and filter the input grid power supply, including a rectifier module, an inverter module, a high-frequency transformer and a high-frequency rectifier and filter module connected in sequence, and finally outputs to the battery unit docking interface (represented as a power interface in the accompanying drawings) through the grid unit; the control unit is used to control the inverter module of the circuit unit and communicate with the computer control unit of the welding machine battery power supply unit.

[0059] The power voltage adjustment unit includes a first contact switch K1, a second contact switch K2, a third contact switch K3, a fourth contact switch K4, a fifth contact switch K5, and a sixth contact switch K6. The third contact switch K3 and the sixth contact switch K6 are successively connected in series on a first line connecting the positive output end of the power grid and the positive pole of the welding machine output interface, the fifth contact switch K5 is connected in series on a second line connecting the negative output end of the power grid and the negative pole of the welding machine output interface, a third line is connected between the positive output end of the DCDC converter and the first line, a contact point between the third line and the first line is located between the third contact switch K3 and the sixth contact switch K6, and the second contact switch K2 is connected in series on the third line. The negative output terminal of the DCDC converter is respectively connected to the front end position and the rear end position of the second circuit where the fifth contact switch K5 is installed through the fourth circuit and the fifth circuit connected in parallel, the first contact switch K1 is connected in series on the fourth circuit, the sixth circuit is connected between the front end of the third circuit where the second contact switch K2 is installed and the rear end of the fourth circuit where the first contact switch K1 is installed, and the fourth contact switch K4 is installed in series on the sixth circuit.

[0060] A seventh circuit is connected between the positive output terminal of the external battery pack and the positive output terminal of the power grid, an eighth circuit is connected between the negative output terminal of the external battery pack and the negative output terminal of the power grid, and a seventh contact switch K7 and an eighth contact switch K8 are respectively connected in series on the seventh circuit and the eighth circuit.

[0061] Based on the power voltage adjustment unit, the working modes of the multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine of the present invention include the following five types:

[0062] Working mode 1:

[0063] The power supply mode is a combination of the grid and the battery in series. In this mode, K1, K2, K5, K7 and K8 are all in the open state, and K3, K4 and K6 are all in the closed state;

[0064] Working mode 2:

[0065] The grid and battery are connected in parallel to provide power. In this mode, K1, K4, K7 and K8 are all in the open state, and K2, K3, K5 and K6 are all in the closed state.

[0066] Working mode three:

[0067] Grid power supply mode, in this mode, K1, K2, K4, K7 and K8 are all in the open state, and K3, K5 and K6 are all in the closed state;

[0068] Working mode 4:

[0069] Battery power supply mode, in this mode, K1, K3, K4, K5, K7 and K8 are all in the open state, and K2 and K6 are in the closed state;

[0070] Working mode five:

[0071] Battery charging mode. In this mode, K1, K2, K3, K4, K5, and K6 are all in the open state, and K7 and K8 are all in the closed state.

[0072] The working method of this multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine is:

[0073] After starting the electric fusion welding machine, first confirm whether to weld. After confirming to weld, read the welding parameters to confirm whether the welding voltage is greater than 40V. If the welding voltage is greater than 40V, confirm whether the battery power meets the welding requirements. If so, set it to 8KVA power supply mode of combined series connection of power grid and battery. The power grid output is connected in series with the battery pack output, and then connected to the output interface of the welding machine. If the battery power does not meet the requirements of the welding machine, an alarm will be issued to prompt charging of the battery.

[0074] If it is confirmed that the welding voltage is not greater than 40V, then confirm whether the welding power is greater than 4VA. If it is greater than 4VA, then confirm whether the battery power meets the welding requirements (sufficient power). If so, set it to 8KVA grid and battery parallel combined power supply mode, and the grid output and battery pack output are connected in parallel to the welding machine output interface; if the battery power does not meet the welding requirements (insufficient power), an alarm is issued to remind you to charge the battery; if the welding power is not greater than 4VA, it is set to 4VA grid power supply mode or battery power supply mode in an optional manner, and it is confirmed according to the specific actual use situation. When the grid power supply mode is adopted, the battery output end is disconnected, and the grid output end is connected to the welding machine output interface via the line. When the battery power supply mode is adopted, the grid output end is disconnected, and the battery output end is connected to the welding machine output interface via the line.

[0075] If it is confirmed that welding is not to be performed, then confirm whether to charge. If it is confirmed that charging is not to be performed, then enter the standby operation. If it is confirmed that charging is to be performed, then set it to charging mode.

[0076] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. A multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine, characterized by: The electric fusion welding machine adopts a two-part plug-in combination structure, including a battery-powered split device and a grid-powered split device; The battery-powered split device includes a battery-powered unit housing, a computer control unit, a power voltage adjustment unit, an external battery pack, and a DCDC converter; A plurality of battery sockets are arranged horizontally on the upper front side of the battery power supply unit housing for plugging in an external battery pack; a welding machine output interface is arranged on the left or right side of the battery power supply unit housing, and a welding machine battery power supply unit working status indicator light is arranged on the same side as the welding machine output interface; a battery unit to power grid unit docking interface is arranged on the rear side of the battery power supply unit housing; the external battery pack is plugged and connected to the battery socket on the battery power supply unit housing; The computer control unit, power voltage adjustment unit and DCDC converter are installed in the housing of the battery power supply unit; the computer control unit is responsible for Bluetooth communication with the mobile phone; the power voltage adjustment unit is used to output and collect various machine signals, and is responsible for allocating and combining power supply from the power grid and power supply from the battery, realizing a separate power supply mode of the two power supply modes or a series power supply mode or a parallel power supply mode of the two power supply modes, and adjusting the output voltage of the welding machine to a constant welding machine voltage value; the DCDC converter is used to convert the direct current input from the external battery pack to meet the output requirements of the electric fusion welding machine; The grid power supply split device comprises a grid power supply unit housing, a control unit and a circuit unit; A power input socket is provided on the top or side of the power supply unit housing for connecting 220V or 380V AC power. A power supply unit to battery unit docking interface is provided on the front side of the power supply unit housing. The power supply unit to battery unit docking interface corresponds to the battery unit to power supply unit docking interface. By plugging and matching the two, power supply of the welding machine to the power supply unit and / or battery charging can be realized. The control unit and the circuit unit are installed in the housing of the power supply unit. The circuit unit is used to rectify and filter the input power supply of the ...

2. The multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine according to claim 1 is characterized in that: The battery power supply unit shell adopts a fully enclosed aluminum alloy box-shaped shell; the front lower part of the battery power supply unit shell adopts a heat dissipation fin structure; a handle is arranged on the top of the battery power supply unit shell; the grid power supply unit shell adopts a fully enclosed aluminum alloy box-shaped shell, the entire rear part of the grid power supply unit shell adopts a heat dissipation fin structure, and a handle is also arranged on the top of the grid power supply unit shell.

3. The multi-source combined power supply battery capacity increase ultra-wide voltage output high-power electric fusion welding machine according to claim 1 is characterized in that: The power voltage adjustment unit includes a first contact switch K1, a second contact switch K2, a third contact switch K3, a fourth contact switch K4, a fifth contact switch K5, and a sixth contact switch K6; the third contact switch K3 and the sixth contact switch K6 are successively connected in series on a first line connecting the positive output end of the power grid and the positive pole of the welding machine output interface, the fifth contact switch K5 is connected in series on a second line connecting the negative output end of the power grid and the negative pole of the welding machine output interface, a third line is connected between the positive output end of the DCDC converter and the first line, the contact point of the third line and the first line is located between the third contact switch K3 and the sixth contact switch K6, and the second contact switch K3 is connected in series on the third line. The negative output terminal of the DCDC converter is connected to the front end position and the rear end position of the second circuit where the fifth contact switch K5 is installed through the fourth circuit and the fifth circuit connected in parallel, respectively; the first contact switch K1 is connected in series on the fourth circuit; the sixth circuit is connected between the front end of the third circuit where the second contact switch K2 is installed and the rear end of the fourth circuit where the first contact switch K1 is installed, and the fourth contact switch K4 is connected in series on the sixth circuit; the seventh circuit is connected between the positive output terminal of the external battery pack and the positive output terminal of the power grid, the eighth circuit is connected between the negative output terminal of the external battery pack and the negative output terminal of the power grid, and the seventh circuit and the eighth circuit are connected in series with the seventh contact switch K7 and the eighth contact switch K8 respectively; When K1, K2, K5, K7 and K8 are all in the open state, and K3, K4 and K6 are all in the closed state, the electric fusion welding machine is in a power supply mode of a combination of a power grid and a battery in series; When K1, K4, K7 and K8 are all in the open state, K2, K3, K5 and K6 are all in the closed state, the electric fusion welding machine is in the parallel combination power supply mode; When K1, K2, K4, K7 and K8 are all in the open state, K3, K5 and K6 are all in the closed state, the electric fusion welding machine is in the grid power supply mode; When K1, K3, K4, K5, K7 and K8 are all in the open state, K2 and K6 are all in the closed state, the electric fusion welding machine is in the battery-powered mode; When K1, K2, K3, K4, K5, and K6 are all in the open state, and K7 and K8 are all in the closed state, the electric fusion welding machine is in the battery charging mode.

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