Hybrid arc welding system

Abstract

To provide a hybrid arc welding system.SOLUTION: A hybrid arc welding system includes a waveform generator comprising a switching type power converter. A welding torch is operatively connected to the switching type power converter to receive electrical energy and produce an electric arc for welding. The system includes an engine generator, and a rectifier connected to receive an output of the engine generator and supply electrical energy to the switching type power converter. A battery is connected to receive an output of the rectifier and supply electrical energy to the switching type power converter. A bidirectional battery charge-discharge circuit is connected between the rectifier and the switching type power converter and comprises first and second electronic switches.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hybrid arc welding system having both an engine-driven generator and a battery for supplying welding current to a welding torch. [Background technology]

[0002] An engine-driven welder includes an internal combustion engine, such as a diesel, gasoline, or liquefied petroleum gas (LPG) engine. The engine drives a generator, which supplies power to a welding power source, which outputs a welding current and voltage. A hybrid engine welder includes a storage battery that can provide additional power to the welding power source to generate the welding current and voltage. The storage battery is charged by the generator when other current demands from the generator are low. Battery charging circuitry adds cost and space required for an engine-driven welder, making it desirable to minimize the number of components and the cost of such charging circuitry. A hybrid welding system is described in U.S. Patent No. 6,239,999, entitled “Hybrid Welding Supply,” published January 1, 2019, and incorporated herein by reference in its entirety. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 10,166,624 Summary of the Invention [Means for solving the problem]

[0004] The following summary presents a simplified overview in order to provide a basic understanding of some aspects of the devices, systems, and / or methods described herein. This summary is not an exhaustive overview of the devices, systems, and / or methods described herein. This summary is not intended to identify key elements or delineate the scope of such devices, systems, and / or methods. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0005] According to one aspect of the present invention, a hybrid arc welding system is provided. The hybrid arc welding system includes a welding waveform generator including a switching power converter. A welding torch is operably connected to the switching power converter to receive electrical energy from the switching power converter and generate an electric arc for welding. The system further includes an engine-powered generator and a rectifier connected to receive the output of the engine-powered generator and provide electrical energy to the switching power converter. A battery is connected to receive the output of the rectifier and provide electrical energy to the switching power converter. A bidirectional battery charge-discharge circuit is connected between the rectifier and the switching power converter. The bidirectional battery charge-discharge circuit includes a first electronic switch and a second electronic switch. A controller is operably connected to the bidirectional battery charge-discharge circuit and controls operation of the first electronic switch and the second electronic switch such that the bidirectional battery charge-discharge circuit is configured to selectively conduct charging current from the rectifier to the battery and selectively conduct welding current from the battery to the switching power converter.

[0006] According to another aspect of the present invention, a hybrid arc welding system is provided. The hybrid arc welding system includes a welding waveform generator including a switching power converter. A welding torch is operably connected to the switching power converter to receive electrical energy from the switching power converter and generate an electric arc for welding. The system further includes an engine-powered generator and a rectifier connected to receive the output of the engine-powered generator and provide electrical energy to the switching power converter. A battery is connected to receive the output of the rectifier and provide electrical energy to the switching power converter. A bidirectional buck-boost circuit is connected between the rectifier and the switching power converter. The bidirectional buck-boost circuit includes a battery charging switch connected in parallel without a separate diode, and a battery discharging switch connected in parallel without a separate diode. A controller is operably connected to the bidirectional buck-boost circuit to control operation of the battery charging switch and the battery discharging switch such that the bidirectional buck-boost circuit is configured to selectively conduct charging current from the rectifier to the battery and selectively conduct welding current from the battery to the switching power converter.

[0007] According to another aspect of the present invention, a hybrid arc welding system is provided. The hybrid arc welding system includes a welding waveform generator including a switching power converter. A welding torch is operably connected to the switching power converter to receive electrical energy from the switching power converter and generate an electric arc for welding. The system further includes an engine-powered generator and a rectifier connected to receive the output of the engine-powered generator and provide electrical energy to the switching power converter via a DC bus. A filter capacitor is connected at the output of the rectifier across the DC bus. A battery is connected to receive the output of the rectifier and provide electrical energy to the switching power converter. A bidirectional buck-boost circuit includes a first electronic switch and an inductor electrically connected between the battery and the first electronic switch. The first electronic switch is electrically connected between the inductor and a positive terminal of the DC bus. The bidirectional buck-boost circuit also includes a second electronic switch electrically connected between the negative terminal of the DC bus and both the inductor and the first electronic switch. A controller is operably connected to the bidirectional buck-boost circuit to control operation of the first electronic switch and the second electronic switch such that the bidirectional buck-boost circuit is configured to selectively conduct charging current from the rectifier to the battery and selectively conduct welding current from the battery to the switching type power converter.

[0008] These and other aspects of the present invention will become apparent to those skilled in the art to which the present invention pertains upon reading the following description and upon reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a perspective view of an engine-driven welder hybrid arc welding system. [Figure 2] 1 is a schematic diagram of an engine-driven welder hybrid arc welding system. [Figure 3] 1 is a schematic diagram of an engine-driven welder hybrid arc welding system. [Figure 4] 1 is a schematic diagram of an engine-driven welder hybrid arc welding system. [Figure 5] 1 is a schematic diagram of an engine-driven welder hybrid arc welding system. [Figure 6] 1 is a schematic diagram of an engine-driven welder hybrid arc welding system. [Figure 7] 1 illustrates an example of a controller. DETAILED DESCRIPTION OF THE INVENTION

[0010] The present invention relates to a hybrid arc welding system having both an engine-driven generator and a battery for supplying welding current to a welding torch. The present invention will now be described with reference to the drawings, in which like reference numerals are used to refer to like elements throughout. It should be understood that the various drawings are not necessarily drawn to scale, either from one drawing to another or within a given drawing, and in particular, the dimensions of components are drawn to arbitrary sizes to facilitate understanding of the drawings. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent that the present invention may be practiced without these specific details. In addition, other embodiments of the present invention are possible, and the present invention may be practiced and carried out in ways other than those described. The terms and phrases used in describing the present invention are used for the purpose of facilitating understanding of the present invention and should not be construed as limiting.

[0011] As used herein, "at least one," "one or more," and "and / or" are open-ended expressions that are both conjunctive and disjunctive in operation. For example, the phrases "at least one of A, B, and C," "at least one of A, B, or C," "one or more of A, B, and C," "one or more of A, B, or C," and "A, B, and / or C" each mean A only, B only, C only, A and B together, A and C together, B and C together, or A, B, and C together. Whether in the description of embodiments, claims, or drawings, disjunctive phrases presenting two or more alternative terms should be understood to contemplate the possibility of including one of those terms, either one of those terms, or both of those terms. For example, the phrase "A or B" should be understood to include the possibilities of "A" or "B," or "A and B."

[0012] Although embodiments of the invention described herein are described in the context of a gas metal arc welding (GMAW) system, other embodiments of the invention are not so limited. For example, embodiments can be utilized in shielded metal arc welding (SAW), flux-cored arc welding (FCAW), metal-cored arc welding (MCAW), gas tungsten arc welding (GTAW), as well as other similar types of welding operations. Furthermore, embodiments of the invention can be used in manual, semi-automated, and robotic welding operations. Embodiments of the invention can also be used in metal deposition operations similar to welding, such as additive manufacturing, hardfacing, and cladding. As used herein, the term "welding" is intended to encompass all of these techniques, as all of these techniques involve the deposition of material to either join or build workpieces. Therefore, for efficiency, the term "welding" is used below in the description of exemplary embodiments, but is intended to include all of these material deposition operations, regardless of whether joining of multiple workpieces occurs.

[0013] FIG. 1 is a perspective view of the exterior of an example engine-driven hybrid arc welder 10 or system. The welder 10 may include a base 12, which is part of the welder's chassis structure, and an outer case or housing 14. A user interface 16 for controlling the operation of the hybrid arc welder 10 is located on the front of the outer case 14. Examples of welding processes that can be performed by the welder 10 include shielded metal arc welding (SMAW), gas metal arc welding (GMAW), flux-cored arc welding (FCAW), gas tungsten arc welding (GTAW), and gouging. Inside the outer case 14 are an internal combustion engine that drives a generator, a hybrid battery, and a welding waveform generator (e.g., welding power circuitry) having a switching-type power converter, such as an inverter or chopper.

[0014] FIG. 2 is a schematic diagram of a hybrid arc welding system, which is an engine-powered welding system with a battery that provides additional welding energy as needed. The welding system includes a generator 30 driven by an engine 28, thereby forming an engine-generator. Examples of engines include diesel engines, gasoline engines, and LPG engines. The generator 30 generates electrical energy to power a welding power source or welding waveform generator having a switching-type power converter 34 (e.g., a chopper or inverter). The generator 30 may be a synchronous three-phase alternator. However, the generator need not be a synchronous three-phase alternator. For example, the generator could be a single-phase alternator or a DC generator, if desired.

[0015] The output of the generator 30 is rectified to DC by a rectifier 32. The rectifier 32 provides DC power to a DC bus 46, which conducts electricity to a switching power converter 34. The engine-driven generator 30 is thus operably connected to a welding waveform generator having a switching power converter 34 (e.g., a chopper or inverter) to provide electrical energy to the welding waveform generator to generate a welding arc 36. The switching power converter 34 converts electrical energy from the generator 30 into a welding output to generate an electric welding arc 36 between a torch 38 and a workpiece 40 to be welded. The welding torch 38 is thus operably connected to the switching power converter 34 to receive electrical energy from the switching power converter and generate the electric arc 36 for welding. The switching power converter 34 can include chopper or inverter circuitry for generating the welding output, control circuitry for controlling the chopper or inverter circuitry, and may include a transformer and one or more rectifiers. The specific construction of welding waveform generators or welding power supplies having switching type power converters such as choppers or inverters is well known to those skilled in the art and will not be described in detail herein.

[0016] The hybrid arc welding system also includes a battery 42 (e.g., a lithium-ion battery) connected to the DC bus 46 through a charge-discharge circuit 44. As is known in the art, the battery 42 can be a single battery or a bank of batteries. The battery 42 is connected to the DC bus 46 and the charge-discharge circuit 44 to receive the output of the rectifier 32 for charging the battery and providing electrical energy to the switching power converter 34. The battery 42 receives charging / recharging power from the generator 30 and the rectifier 32 through the charge-discharge circuit 44. The battery 42 also provides welding current to the switching power converter 34 through the charge-discharge circuit 44. The battery 42 can assist the engine 28 and generator 30 in providing power for welding and other auxiliary operations, or the battery can itself provide power for welding and / or auxiliary operations. The battery 42 is connected to power the torch 38 and / or auxiliary output, either independently of the generator 30 or in conjunction with the generator. In this sense, power can be provided by at least one of the engine-driven generator 30 and the battery 42, such that sufficient power to perform the operation may be provided independently by the generator or the battery, or the battery may supplement the power from the generator.

[0017] In conventional hybrid arc welding systems, the charge / discharge circuit 44 is not bidirectional. For example, the charge / discharge circuit 44 may include separate buck and boost sub-circuits to respectively charge and discharge the battery 42. Alternatively, and preferably, the charge-discharge circuit 44 may be a bidirectional battery charge-discharge circuit (e.g., a bidirectional buck-boost circuit) that combines the buck and boost sub-circuits to minimize the number of charge / discharge circuit components, thereby reducing system cost and the spatial footprint of the charge / discharge circuit.

[0018] FIG. 3 is a schematic diagram of a hybrid arc welding system without a bidirectional charge-discharge circuit. The hybrid battery 42 is charged from the DC bus 46 through a buck subcircuit 50. The buck subcircuit 50 may include an electronic switch, such as a transistor switch, a diode, and an inductor, as shown. The electronic switch of the buck subcircuit 50 operates to charge the battery 42 at a lower voltage than the DC bus 46 when the engine 28 is running and there is sufficient reserve capacity from the generator 30 (e.g., when welding is not occurring). The battery 42 is discharged to provide welding power to the DC bus 46 through a boost subcircuit 52. The boost subcircuit 52 may include an additional electronic switch, an inductor, and a diode, as shown. The electronic switch of the boost subcircuit 52 operates to discharge the battery 42 and increase its voltage to that of the DC bus 46. The welding system may include one or more controllers 54. The controller 54 controls the operation of a switching type power converter (shown in FIG. 3 as a welding chopper) to generate the desired welding waveform using, for example, pulse width modulation control. The controller 54 may also control the operation of the electronic switches in the buck subcircuit 50 and the boost subcircuit 52, or separate controllers may be provided for those subcircuits. In either case, the operation of the charge-discharge circuit may be controlled based on the charge level of the battery 42, the load on the engine-generator, the desired amount of welding current, etc., which may be monitored and / or determined by the controller 54.

[0019] FIG. 4 is a schematic diagram of a hybrid arc welding system including a bidirectional charge-discharge circuit or bidirectional buck-boost circuit 56. In FIG. 3, charging and discharging of the battery 42 are accomplished via separate subcircuits with separate inductors / chokes, electronic switches, and current paths. However, the bidirectional buck-boost circuit 56 of FIG. 4 includes a combined current path utilizing a battery charging electronic switch 58 and a battery discharging electronic switch 60, as well as a single inductor 62. The battery charging switch 58 is directly connected to the DC bus 46 (e.g., the positive rail of the DC bus), a filter capacitor 64, and the battery discharging switch 60. The battery discharging switch 60 is directly connected to the battery charging switch 58, an inductor 62 (battery choke), and the DC bus 46 (e.g., the negative rail of the DC bus). The inductor 62 is electrically connected between the battery 42 and the connection of the charging switch 58 to the discharging switch 60. Compared to the circuitry of FIG. 3, the bidirectional charge-discharge circuit or bidirectional buck-boost circuit 56 of FIG. 4 includes fewer components and occupies less space. Furthermore, efficiency can be increased by using synchronous rectification using electronic switches 58, 60.

[0020] In the example embodiment shown in FIG. 4, the battery charging switch 58 and the battery discharging switch 60 may be electronic switches, such as transistor switches. For example, the electronic switches could be power transistors, IGBTs, MOSFETs, etc. Each electronic switch could have a separate diode electrically connected in parallel with the electronic switch, as shown in FIG. 6. However, when MOSFETs are used, as shown in FIGS. 4 and 5, intrinsic body diodes can be utilized to provide synchronous rectification and increase efficiency. Thus, if desired, the battery charging switch and the battery discharging switch do not need separate respective diodes connected in parallel, as shown in FIG. 6. The intrinsic body diodes of the battery charging switch 58 and the battery discharging switch 60 are shown in FIG. 4 but not in FIG. 5.

[0021] Referring to FIG. 4, a bidirectional buck-boost circuit 56 is connected to the DC bus 46 between the rectifier 32 and the switching power converter 34. To charge the battery 42 from the generator 30, the gate of a battery charging switch 58 is controlled (e.g., via pulse-width modulation (PWM), pulse-frequency modulation, etc.) to create a flow of charging current to the battery. If synchronous rectification is not performed and the battery discharging switch 60 has a separate parallel diode, the battery discharging switch can remain off while the battery is charging. However, if synchronous rectification is performed, the battery discharging switch 60 is activated via its gate when the battery charging switch 58 turns off during PWM and after the dead band (to prevent both switches from being activated simultaneously).

[0022] To discharge the battery 42 and provide power to the DC bus 46, the gate of the battery discharge switch 60 is controlled (e.g., via PWM) to create a discharge current flow from the battery. If synchronous rectification is not performed and the battery charge switch 58 has a separate parallel diode, the battery charge switch can remain off during battery discharge. However, if synchronous rectification is performed, the battery charge switch 58 is activated via its gate when the battery discharge switch 60 is turned off during PWM and after the dead band (to prevent both switches from being activated simultaneously).

[0023] It should be appreciated that the duty cycles of the battery charge switch 58 and the battery discharge switch 60 control the energy into the inductor 62 or battery choke. When charging the battery 42, the shorter the PWM duty cycle of the battery charge switch 58, the greater the voltage drop from the DC bus 46. When discharging the battery 42, the longer the PWM duty cycle of the battery discharge switch 60, the greater the voltage boost from the battery to the DC bus 46.

[0024] The bidirectional buck-boost circuit 56 may include a filter capacitor 64 connected across the output of the rectifier 32 to prevent surge currents due to overvoltage conditions to the battery charge switch 58 and the battery discharge switch 60 and to provide additional filtering from the AC.

[0025] As described above, the welding system can include one or more controllers. The controller 54 controls the operation of the switching power converter 34 (shown in FIG. 4 as a welding chopper, but could also be an inverter) to generate a desired welding waveform using, for example, PWM control. The controller 54 can also control the operation of the bidirectional charge-discharge circuit or bidirectional buck-boost circuit 56, particularly the operation of the charge electronic switch 58 and the discharge electronic switch 60 of the charge-discharge circuit. However, in the example embodiment of FIG. 4 , the welding system includes a separate controller 66 for controlling the operation of the charge electronic switch 58 and the discharge electronic switch 60 of the bidirectional charge-discharge circuit or bidirectional buck-boost circuit 56. The controller 66 is operably connected to the bidirectional battery charge-discharge circuit or bidirectional buck-boost circuit to control the operation of the charge electronic switch 58 and the discharge electronic switch 60 such that the bidirectional battery charge-discharge circuit or bidirectional buck-boost circuit is configured to selectively conduct a charging current from the rectifier 32 to the battery 42 and a welding current from the battery to the switching power converter 34. The controller 66 of the bidirectional buck-boost circuit 56 can provide PWM and synchronous rectification signals to the charge electronic switch 58 and the discharge electronic switch 60 to provide charge and discharge currents to the battery 42 at appropriate voltage levels. Operation of the bidirectional charge-discharge circuit or the bidirectional buck-boost circuit 56 can be controlled based on the charge level of the battery 42, the load on the engine-generator, the desired amount of welding current, etc., which can be monitored and / or determined by one or both of the controllers 54, 66. In certain embodiments, the controller 54 of the switching type power converter 34 can monitor parameters such as engine RPM, welding voltage level, welding current level, DC bus voltage level, etc., and communicate power or PWM adjustments to the controller 66 to cause the bidirectional buck-boost circuit 56 to increase or decrease the charge and / or discharge current from the hybrid battery 42. For example, the controllers 54, 66 can communicate bidirectionally, for example, via a CAN bus.The controller 54 of the switching power converter 34 can command the controller 66 of the bidirectional buck-boost circuit 56 to increase and / or decrease power to or from the hybrid battery 42, and the controller of the bidirectional buck-boost circuit 56 can appropriately control the operation and synchronous rectification of the charge electronic switch 58 and the discharge electronic switch 60. PWM adjustment of the charge electronic switch 58 and the discharge electronic switch 60 can be performed dynamically during operation of the generator 30 and / or during a welding operation.

[0026] FIG. 5 is a schematic diagram of a hybrid arc welding system having a bidirectional charge-discharge or bidirectional buck-boost circuit 56, in which the charge electronic switch 58a and the discharge electronic switch 60a are MOSFETs without separate diodes connected in parallel. A controller 66 for the bidirectional buck-boost circuit 56 controls the operation of the switches 58a and 60a to provide synchronous rectification using the intrinsic body diodes (not shown) of the MOSFET switches. The switches 58a and 60a operate together during battery charging and discharging, with a dead band between switch activations to prevent both switches from being activated simultaneously. FIG. 6 is a schematic diagram of a hybrid arc welding system having a bidirectional charge-discharge or bidirectional buck-boost circuit 56, in which the charge electronic switch 58a and the discharge electronic switch 60a are MOSFETs with separate diodes 59 and 61 connected in parallel with the switches (apart from the intrinsic body diodes).

[0027] The hybrid arc welding systems described herein may include auxiliary outputs for powering devices such as lights, grinders, various plug-in handheld tools, etc. In certain embodiments, the hybrid arc welding system may include an inverter connected to the hybrid battery through a contactor to provide an auxiliary power output.

[0028] 7 illustrates an example embodiment of a controller 800 for use in the example hybrid arc welding system described above (e.g., a controller for a switching power converter and / or a controller for hybrid battery charge-discharge circuitry). The example controller 800 includes at least one processor 814 that communicates with multiple peripheral devices via a bus subsystem 812. These peripheral devices may include, for example, a storage subsystem 824 including a memory subsystem 828 and a file storage subsystem 826, a user interface input device 822, a user interface output device 820, and a network interface subsystem 816. The input and output devices enable user interaction with the controller 800. The network interface subsystem 816 provides an interface to an external network and may be coupled to corresponding interface devices in other computer systems or programmable devices.

[0029] The user interface input devices 822 may include pointing devices such as a keyboard, a mouse, a trackball, a touchpad, or a graphics tablet, an audio input device such as a scanner, a touch screen integrated into a display, a voice recognition system, a microphone, and / or other types of input devices. In general, use of the term "input device" is intended to include all possible types of devices and ways of inputting information into the controller 800 or a communications network.

[0030] The user interface output devices 820 may include a display subsystem, a printer, a fax machine, or a non-visual display such as an audio output device. The display subsystem may include a flat panel device such as a cathode ray tube (CRT), a liquid crystal display (LCD), a projection device, or some other mechanism for producing a visible image. The display subsystem may also provide a non-visual display, such as through an audio output device. In general, use of the term "output device" is intended to include all possible types of devices and ways for outputting information from the controller 800 to a user or to another machine or computer system.

[0031] The storage subsystem 824 stores programming and data structures that provide the functionality for some or all of the operations described herein. For example, the storage subsystem 824 may include programming instructions that enable the controller 800 to perform the PID routines and consumable identification described above.

[0032] Firmware or software modules having program instructions are generally executed by processor 814 alone or in combination with other processors. The memory subsystem 828 used in storage subsystem 824 can include multiple memories, including a main random access memory (RAM) 830 for storing instructions and data during program execution and a read-only memory (ROM) 832 in which fixed instructions are stored. The file storage subsystem 826 can provide persistent storage of program and data files and may include a hard disk drive, a floppy disk drive with associated removable media, a CD-ROM drive, an optical drive, or a cartridge of removable media. Modules implementing the functionality of certain embodiments may be stored by file storage subsystem 826 in storage subsystem 824 or on another machine accessible by processor 814.

[0033] Bus subsystem 812 provides a mechanism for allowing the various components and subsystems of controller 800 to communicate with each other as intended. Although bus subsystem 812 is shown schematically as a single bus, alternative embodiments of the bus subsystem may use multiple buses.

[0034] It should be understood that the present disclosure is by way of example, and that various modifications can be made by adding, modifying, or deleting details without departing from the fair scope of the teachings contained herein. Accordingly, the present invention is not limited to the particular details of this disclosure, except to the extent that the following claims are necessarily so limited. [Explanation of symbols]

[0035] 10. Engine-driven hybrid arc welding machine 12 base 14 Outer case 16 User Interface 28 Engine 30 Generator 32 Rectifier 34 Switching-type power converter 36 Welding Arc 38 Torch 40 workpieces 42 Battery 44 Charge-discharge circuit 46 DC bus 50 Back Sub-Circuit 52 Boost sub-circuit 54 Controller 56 Buck-Boost Circuit 58 Battery charging electronic switch 58a Charging electronic switch 59 Diode 60 Battery Discharge Electronic Switch 60a discharge electronic switch 61 Diode 62 Inductor 64 Filter Capacitor 66 Controller 800 Controller 812 Bus Subsystem 814 processor 816 Network Interface Subsystem 820 User Interface Output Device 822 User Interface Input Devices 824 Storage Subsystem 826 File Storage Subsystem 828 Memory Subsystem 830 Random Access Memory 832 read-only memory

Claims

1. 1. A hybrid arc welding system comprising: a welding waveform generator including a switching type power converter; a welding torch operatively connected to the switching power converter to receive electrical energy from the switching power converter and generate an electric arc for welding; An engine generator, a rectifier connected to receive the output of the engine generator and to provide electrical energy to the switching power converter; a battery connected to receive the output of the rectifier and to provide electrical energy to the switching power converter; a bidirectional battery charge-discharge circuit connected between the rectifier and the switching power converter, the bidirectional battery charge-discharge circuit including a first electronic switch and a second electronic switch; a controller operatively connected to the bidirectional battery charge-discharge circuit for controlling operation of the first electronic switch and the second electronic switch such that the bidirectional battery charge-discharge circuit is configured to selectively conduct a charging current from the rectifier to the battery and a welding current from the battery to the switching power converter; Hybrid arc welding system including:

2. The hybrid arc welding system of claim 1 , wherein the first electronic switch and the second electronic switch are MOSFET switches.

3. The hybrid arc welding system of claim 2 , wherein the controller controls operation of the first electronic switch and the second electronic switch to perform synchronous rectification.

4. 10. The hybrid arc welding system of claim 1, further comprising: a first diode electrically connected in parallel with the first electronic switch; and a second diode electrically connected in parallel with the second electronic switch.

5. The hybrid arc welding system of claim 1 further comprising a filter capacitor connected across the output of the rectifier.

6. 6. The hybrid arc welding system of claim 5, wherein the bidirectional battery charge-discharge circuit further includes an inductor electrically connected between the battery and a connection of the first electronic switch to the second electronic switch.

7. The hybrid arc welding system of claim 1 , wherein the first electronic switch is directly connected to the second electronic switch.

8. 1. A hybrid arc welding system comprising: a welding waveform generator including a switching type power converter; a welding torch operatively connected to the switching power converter to receive electrical energy from the switching power converter and generate an electric arc for welding; An engine generator, a rectifier connected to receive the output of the engine generator and to provide electrical energy to the switching power converter; a battery connected to receive the output of the rectifier and to provide electrical energy to the switching power converter; a bidirectional buck-boost circuit connected between the rectifier and the switching power converter, the bidirectional buck-boost circuit including a battery charging switch, the battery charging switch being connected in parallel without a separate diode, and a battery discharging switch, the battery discharging switch being connected in parallel without a separate diode; a controller operatively connected to the bidirectional buck-boost circuit for controlling operation of the battery charge switch and the battery discharge switch such that the bidirectional buck-boost circuit is configured to selectively conduct a charging current from the rectifier to the battery and a welding current from the battery to the switching power converter; Hybrid arc welding system including:

9. The hybrid arc welding system of claim 8 , wherein the battery charging switch and the battery discharging switch are MOSFET switches.

10. The hybrid arc welding system of claim 8 , wherein the controller controls operation of the battery charge switch and the battery discharge switch to perform synchronous rectification.

11. The hybrid arc welding system of claim 8 further comprising a filter capacitor connected across the output of the rectifier.

12. 12. The hybrid arc welding system of claim 11, wherein the bidirectional buck-boost circuit further includes an inductor electrically connected between the battery and a connection of the battery charge switch to the battery discharge switch.

13. The hybrid arc welding system of claim 8 , wherein the battery charging switch is directly connected to the battery discharging switch.

14. 1. A hybrid arc welding system comprising: a welding waveform generator including a switching type power converter; a welding torch operatively connected to the switching power converter to receive electrical energy from the switching power converter and generate an electric arc for welding; An engine generator, a rectifier connected to receive the output of the engine generator and to provide electrical energy to the switching power converter via a DC bus; a filter capacitor connected at the output of the rectifier across the DC bus; a battery connected to receive the output of the rectifier and to provide electrical energy to the switching power converter; 1. A bidirectional buck-boost circuit comprising: a first electronic switch; an inductor electrically connected between the battery and the first electronic switch, the first electronic switch being electrically connected between itself and the positive terminal of the DC bus; and a second electronic switch electrically connected between the negative terminal of the DC bus and both the inductor and the first electronic switch; a bidirectional buck-boost circuit including: a controller operatively connected to the bidirectional buck-boost circuit for controlling operation of the first electronic switch and the second electronic switch such that the bidirectional buck-boost circuit is configured to selectively conduct charging current from the rectifier to the battery and selectively conduct welding current from the battery to the switched-mode power converter; Hybrid arc welding system including:

15. The hybrid arc welding system of claim 14 , wherein the first electronic switch and the second electronic switch are MOSFET switches.

16. The hybrid arc welding system of claim 15 , wherein the controller controls operation of the first electronic switch and the second electronic switch to perform synchronous rectification.

17. 15. The hybrid arc welding system of claim 14, further comprising: a first diode electrically connected in parallel with the first electronic switch; and a second diode electrically connected in parallel with the second electronic switch.

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