Patent Description:
MIG/MAG-welding takes place in one of three basic metal transfer modes: short arc, mixed arc, and spray. In short arc welding, the material transport from the electrode to the workpiece takes place through short-circuiting droplets.

When the supplied power is increased, the process passes into a mixed arc area, where material transport takes place through a mixture of short-circuiting and non-short-circuiting droplets. The result is an unstable arc which is difficult to control with a risk for much weld spatter and weld smoke. Welding in this area is normally avoided.

At a sufficiently high supplied power, the process enters the spray area, where the material transport takes place through small finely dispersed droplets without short circuits. The spatter quantity is clearly lower than in short arc welding. The heat supply to the base material in this mode is greater and the method is suitable primarily for thicker workpieces.

With reference to the short arc welding modes, portions of a welding cycle constituting a short circuit condition are followed by an arcing (non-short circuit) condition. During the short circuit condition, a molten metal ball formed on the end of the advancing welding wire engages the molten metal pool on the workpiece causing a high current flow through the consumable welding wire and molten metal ball. This short circuit condition is terminated by an electrical pinch action causing the metal forming the molten ball on the wire to electrically constrict and then break away from the welding wire in an explosion type action often referred to as a "fuse" or "the fuse". Controlling current flow during the short circuit portion of the welding cycle is accomplished by the power supply control circuit. A premonition circuit is usually provided so that a given increase in dv/dt (i.e., the slope of the voltage) signals the imminent formation of the fuse. By knowing change of voltage over time, the welding current can be controlled down to a background level, or lower, immediately before the fuse occurs. In this way, the energy of the fuse during each welding cycle is drastically reduced. This, in turn, reduces spatter at the termination of the short circuit condition.

In one prior art approach, in order to quickly reduce the current being supplied at the appropriate moment, i.e., just before the fuse, a switch, disposed in the ordinary current path toward a welding zone, may turned off thereby forcing the current to instead pass through a resistor which increases the voltage drop in the overall welding circuit thus causing the welding current to more quickly ramp down to a lower level. This general approach may be referred to as "current braking.

<CIT> discloses an apparatus and a method for saving the energy consumption during short arc welding.

The embodiments described herein improve upon current braking approaches.

Disclosed herein are techniques for improving a short arc welding process. A method includes ramping down a welding current, generated by a power supply, that reaches a welding zone via a welding circuit, storing inductive energy from the welding circuit that is generated as a result of the ramping down to obtain stored energy, and selectively feeding the stored energy to the welding circuit.

An apparatus is also disclosed and may include a power source configured to deliver welding current to a welding zone via a welding circuit, a current brake disposed between the power source and the welding zone, and a braking energy recovery module configured to: ramp down the welding current that reaches the welding zone via the welding circuit, store inductive energy from the welding circuit that is generated as a result of the ramp down to obtain stored energy, and selectively feed the stored energy to the welding circuit.

Like numerals identify like components throughout the figures.

The reason to implement a current brake in the context of short arc welding is to speed up the ramping down of the welding current while the melted droplet is still shorting the welding arc. Without a current brake the current will normally freewheel for too long because the voltage drop in the droplet and the rest of the welding circuit is rather low, typically <NUM> - 15V. By implementing a current brake either according to the prior art or in accordance with the techniques described herein the total voltage drop in the welding circuit can be on the order of <NUM> - 300V depending on the design of the circuit. The freewheeling time will be shortened proportional to the increased voltage. That is, given U = L * di/dt, then dt = L *di /U meaning that the freewheeling time is shorter if U is relatively large and if L is relatively small.

If the power source is fast (high inverter frequency and small output inductor) and the welding cables are relatively short (such that L is low) it may be possible to ramp down the welding current fast enough by controlling only the power source without a current brake.

However, such an ideal overall system cannot be assumed. As such, a current brake makes it possible to ramp down the current fast enough even if the output inductor is relatively large and the welding cables are relative long (resulting in higher inductance). The disadvantage is then be higher inductive energy in the welding circuit (W = ½ * L * I<NUM> ) in every braking operation, and braking may occur on the order of <NUM> - <NUM> times per second which will result in significant power loss if the braking energy is merely dissipated as heat in a resistor as is the case in the prior art.

More specifically, <FIG> is a schematic diagram of a welding power supply with a current braking circuit according to the prior art. The power supply <NUM> includes a power source <NUM>, a current brake <NUM>, and a welding zone <NUM>. Power source <NUM> includes a current source I1, a voltage source V1, internal resistance R1, and diodes D1, D2, and D3. Voltage source and diode D1 are shown in the circuit of <FIG>, which was simulated. In that sense, V1 and D1 are used to limit the voltage from current source I1, which could otherwise by modeled as infinite. The current brake <NUM> includes switch S1, diode D4-<NUM>, capacitor C1 and discharge resistor R12. The welding zone <NUM> is represented by resistance R2 operating in a short arc welding process, and connected to the power source <NUM> via cables having inductances L3 and L4.

In operation, switch S1 carries the whole welding current in parallel with diode D4-<NUM> and capacitor C1, and discharge resistor R12 in parallel with capacitor C1. When switch S1 is turned off, welding current will go through diode D4-<NUM>, resistor R12, and charge capacitor C1 and produce a high voltage drop over those components. The peak voltage over capacitor C1 is determined by capacitor C1's capacitance value, the parallel discharge resistance R12 and the inductance in the welding circuit (i.e., L1, L3, L4). The capacitance in capacitor C1 should not be chosen to be too high because current braking starts at 0V over the capacitor C1, and capacitor C1 needs to build up sufficient voltage during braking to be effective.

There are several drawbacks associated with the approach shown in <FIG>. First, there is high power loss in the discharge resistor R12 over capacitor C1. <NUM> - <NUM> W average power loss can occur in the discharge resistor R12 with long welding cables (e.g., on the order of <NUM>) or cables that are coiled up. that is, L3+L4 might equal approximately 50µH (plus the output inductance of inductor L1 in power source <NUM>). Second, there can be high peak voltage over capacitor C1 and also over switch S1. Extra margin in blocking voltage on switch S1 is thus needed to cover variations in welding cable inductance. And, a user might wind the welding cables which results in even higher inductance and higher peak voltage over switch S1. Third, a higher voltage rating on switch S1 normally results in a higher voltage drop during conduction and more conduction loss especially at high output current from the power source <NUM>. As an example, if a 600V IGBT is used as switch S1 it would probably have Vce sat = 1V or more, and at 500A this would give an extra loss of 500W which creates extra heat and reduces efficiency of the power supply.

<FIG> is a high level schematic diagram of a welding power supply with current braking energy recovery according to an example embodiment. As shown, the welding power supply <NUM> includes the power source <NUM> and welding zone <NUM> similar to the configuration shown in <FIG>. A current brake <NUM> includes switch S1, diode D4-<NUM> and capacitor C1. In addition, a braking energy recovery module <NUM> is provided. As will become apparent in connection with <FIG>, to a large degree, the components of braking energy recovery module <NUM> are arranged to be operable with capacitor C1, and configured to store inductive energy generated by current braking, and then return the stored energy to the welding circuit.

In operation, the power source <NUM> delivers welding current with switch S1 conducting. In GMA short arc (with melted droplets shorting the arc) some metal spatter usually occurs when the droplet detaches at high current level. This metal spatter can be reduced by decreasing the welding current rapidly during short circuit just before the melted droplet detaches. A typical DC welding power source can ramp down the current itself with switch S1 conducting but the inductance L3, L4 in the welding cables and the output inductor L1 in the power source <NUM> will make the current freewheel, which slows down the desired quick ramp down in current. That is, as previously noted, it is preferable to ramp down the current faster. The voltage drop in the welding circuit is mostly determined by the welding wire stick out, typically <NUM> - 15V when current is ramping down, and such a low voltage drop results in relatively long freewheeling. By adding the current brake <NUM>, an additional, much higher, voltage drop can be introduced in the circuit which can make current decrease faster.

A goal of the embodiments described herein is to store the inductive energy in capacitor C1 during current braking and then feed that energy back into the welding circuit using the braking energy recovery module <NUM> when braking is finished.

<FIG> is a detailed schematic diagram of a welding power supply with current braking energy recovery according to an example embodiment. In the depicted embodiment, a current brake with capacitor clamp and braking energy recovery module <NUM> is provided. Power source <NUM> and welding zone <NUM> are the same as previously described. In the case of the embodiment depicted in <FIG>, a buck converter <NUM> comprising capacitor C1, switch S2, inductor L2 and diode D5 is provided. Those skilled in the art will appreciate that other forms of converters could be employed, such as DC-DC converter. Diode D4 provides similar functionality as diode D4-<NUM> in, e.g., <FIG>, but is located in a slightly different position and is oriented differently. Also, diode D6, connected to welding output minus (-) is used to block current if welding voltage goes higher than the voltage over capacitor C1, which may happen at welding starts. Diode D6 is thus employed to avoid arc outs and also to protect the body diode in switch S2 if switch S2 is a MOSFET transistor. Braking energy is stored in capacitor C1 and then fed back to the welding circuit under the control by the buck converter <NUM> that is controlled via switch S2. Power supply control logic <NUM> is provided to control switch S1 and switch S2 via gate G1 and gate G2, respectively.

At a high level, the circuit of <FIG> operates, under the control of power supply control logic <NUM>, as follows.

In one embodiment diode D5 and/or diode D6 can be replaced with a MOSFET transistor with its body diode oriented in the same direction as the diode it is replacing. Such a configuration may reduce the forward voltage drop and improve efficiency, but will of course require additional control from power supply control logic <NUM>.

The braking energy recovery approach described herein has several benefits compared to the conventional technique illustrated by <FIG>. For example, lower losses and higher efficiency is possible. Specifically, braking energy with, e.g., <NUM> long welding cables, might be approximately 660W in a typical welding system. With braking energy recovery, approximately <NUM>% (or more) of the braking energy can be fed back into the welding circuit as welding current. As such, losses may be reduced from approximately 660W to approximately 66W (or less).

Further, lower conduction loss in brake switch S1 is achieved. By using controlled braking energy recovery, capacitor C1 can have larger capacitance with a more constant voltage over it. Compared to the conventional technique the peak voltage over capacitor C1 / switch S1 can be reduced. Voltage over capacitor C1 / switch S1 will rise more slowly during braking, and braking can more easily be stopped to limit the peak voltage. As an example, by limiting the peak voltage, a 200V MOSFET transistor with significantly lower conduction loss can be used. That is, by changing, for example, from a 600V low saturation IGBT to a 200V MOSFET, conduction loss at 500A could be reduced from approximately 500W to approximately 170W. Thus, lower cost and less cooling may be realized.

The described braking energy recovery approach also enables more possibilities to control the discharge of capacitor C1. For example, it is possible to use a lower voltage over capacitor C1 when inductance in the welding circuit is lower to get the desired di/dt during braking. The recovery current can be controlled by power supply control logic <NUM> in both level and time to fit the welding process in the best way.

The voltage over the capacitor C1 is preferably limited to 113V or 141V due to open circuit voltage standards which might result is slightly slower braking compared to the conventional technique. If faster braking is desired, a resonant circuit can be added which would increase the peak voltage over switch S1 (resulting in faster braking) and voltage over capacitor C1 can still be limited to 113V.

<FIG> is a schematic diagram of a welding power supply with current braking energy recovery including a resonant circuit according to an example embodiment. As shown, switches S1 and S2 may be the same as those in <FIG>, with switch S1 controlled to provide current braking, and switch S2 being controlled to selectively return stored energy on C31 to the welding circuit, when S1 closes again after a braking cycle. The circuit comprises diode D36 in series with C33 and R33, and inductor L32 connected between an output of switch S2 and a node between D36 and C33. Diode D35 is connected between the output of switch S2 and an input side of switch S1. Diode D310 is connected across switch S2. Diode D310 may instead be included as a body diode in S2 if S2 is a MOSFET.

Diode D39 is connected across the output and input of switch S1. C31 is connected between the input side of switch S1 and the input side of switch S2. Diode D34, inductor L35 and diode D38 are connected in series between the input side of switch S2 and the output side of switch S1 (i.e., the plus welding power output). Capacitor C32 and diode D37 are connected in parallel between the input side of switch S1 and a node between L35 and D38.

In the circuit of <FIG>, R33 and C33 function as a filter to suppress ripple on the output voltage and EMI. This filter can be fairly small because it is within the recovery circuit (D36 separating it from the welding output). R33 may be low resistance or even shorted. The resonant circuit is made up of C32, D37, D34, L35, and D38. With this solution, the peak voltage over switch S1 can be much higher during braking (thus providing faster braking but will again require higher voltage rating on S1) and the voltage on C31 (C1 in <FIG>) can still be kept below 113V, thereby providing a very flexible and safe solution regarding OCV, etc. Those skilled in the art will appreciate that <FIG> shows only one variant of a filter and resonant circuit. These elements may be implemented using different components and topologies.

A detailed description of the operation of the embodiment of <FIG> is now provided in connection with <FIG>.

<FIG> is a graph of current and voltage at different stages of one arc and short circuit cycle in a short arc welding process aided by a braking energy recovery approach according to an example embodiment. The several indicated time points along the graph are defined as in the following table.

<FIG> show current paths through the circuit of <FIG> at the different stages or time points of the cycle shown in <FIG> according to an example embodiment.

<FIG> represents the sequence of time points "400a - 400d" of <FIG>, wherein switch S1 is conducting and the power source delivers welding current to the welding zone <NUM>.

<FIG> represents the sequence of time points 400d, 400d1, and 400e of <FIG>, namely, braking, wherein switch S1 and power source <NUM> are turned off and current is ramping down fast, freewheeling through capacitor C1, diode D4. The voltage over capacitor C1 and the total inductance in L1, L3, L4 determines how fast the welding current is ramping down. The voltage over stick out (R2) is approximately <NUM> - 15V.

<FIG> represents time point 400e of <FIG>, wherein switch S1 is turned on again, and braking is finished. Current is still decreasing but slower than before.

<FIG> represents the sequence of time points 400e - 400e1, which correspond to a braking energy recovery start up stage. In this stage, switch S1 stays on. Switch S2 also turns on, and current ramps up in inductor L2, switch S2, and capacitor C1. Then, switch S2 turns off and current freewheels through D5. This switching of switch S2 (i.e., the controlled operation of buck converter <NUM>) is repeated to bleed off voltage built up on capacitor C1 and to thus deliver the recovered braking energy back to the welding circuit. Power source <NUM> also starts up and delivers welding current in parallel with the recovery circuit.

<FIG> represents the time points 400e1 - <NUM> - 400a, wherein power source <NUM> delivers current in parallel with the braking energy recovery circuit.

<FIG> represents the time points "400e1, 400f, 400b", wherein the buck converter <NUM> continues delivering a part of the current (<NUM> - 50A) until capacitor C1 has been discharged to a desired level, switch S2 turns off and the power source <NUM> alone delivers the welding current.

<FIG> depict graphs of a simulation of braking energy recovery according to an example embodiment. <FIG> shows current through inductance L3 reducing from 350A to 50A at the same time that the voltage drops at the output (at diode D3) of the power supply <NUM>. <FIG> shows how the arc voltage at the welding zone <NUM> decreases more slowly due to inductance in the welding circuit. <FIG> shows voltage across capacitor C1 increasing due to current braking. <FIG> shows the power (voltage x current) handled by capacitor C1 during current braking. <FIG> shows multiple cycles of arc voltage in the welding zone <NUM>. <FIG> shows the corresponding current being delivered at the welding zone <NUM>. <FIG> shows multiple cycles of braking energy recovery, i.e., energy being returned to the welding circuit after a short, and current brake operation. And <FIG> shows build-up of voltage over capacitor C1 from welding start to steady state operation.

<FIG> is a flow chart illustrating a series of operations for operating a current braking energy recovery approach according to an example embodiment. At <NUM>, logic, e.g., power supply control logic <NUM>, is configured to ramp down a welding current, generated by a power supply or source, that reaches a welding zone via a welding circuit. The logic, at <NUM>, is further configured to store inductive energy that i s generated as a result of the ramping down to obtain stored energy. And, at <NUM>, the logic is configured to selectively feed the stored energy back to the welding circuit.

<FIG> depicts a computing device that is part of a welding power supply that may be configured to execute, among other things, the series of operations of <FIG> according to an example embodiment. More specifically, <FIG> depicts a device (e.g., a welding power supply, or portions thereof) that executes power supply control logic <NUM> to perform the operations described herein. It should be appreciated that <FIG> provides only an illustration of one embodiment and does not imply any limitations with regard to the environments in which different embodiments may be implemented. Many modifications to the depicted environment may be made. Indeed, in many implementations of a controller configured to host power supply control logic <NUM>, much of the hardware described below may not be needed.

As depicted, the device <NUM> includes a bus <NUM>, which provides communications between computer processor(s) <NUM>, memory <NUM>, persistent storage <NUM>, communications unit <NUM>, and input/output (I/O) interface(s) <NUM>. Bus <NUM> can be implemented with any architecture designed for passing data and/or control information between processors (such as microprocessors, communications and network processors, etc.), system memory, peripheral devices, and any other hardware components within a system. For example, bus <NUM> can be implemented with one or more buses.

Memory <NUM> and persistent storage <NUM> are computer readable storage media. In the depicted embodiment, memory <NUM> includes random access memory (RAM) <NUM> and cache memory <NUM>. In general, memory <NUM> can include any suitable volatile or non-volatile computer readable storage media. Instructions for appropriate logic may be stored in memory <NUM> or persistent storage <NUM> for execution by processor(s) <NUM>.

One or more programs may be stored in persistent storage <NUM> for execution by one or more of the respective computer processors <NUM> via one or more memories of memory <NUM>. The persistent storage <NUM> may be a magnetic hard disk drive, a solid state hard drive, a semiconductor storage device, read-only memory (ROM), erasable programmable read-only memory (EPROM), flash memory, or any other computer readable storage media that is capable of storing program instructions or digital information.

Communications unit <NUM>, in these examples, provides for communications with other data processing systems or devices. In these examples, communications unit <NUM> includes one or more network interface cards. Communications unit <NUM> may provide communications through the use of either or both physical and wireless communications links.

I/O interface(s) <NUM> allows for input and output of data with other devices that may be connected to computer device <NUM>. For example, I/O interface <NUM> may provide a connection to external devices <NUM> such as a keyboard, keypad, a touch screen, and/or some other suitable input device. External devices <NUM> can also include portable computer readable storage media such as database systems, thumb drives, portable optical or magnetic disks, and memory cards. Gates G1 and G2 of switches S1 and S2 may also be connected via I/O interface(s) <NUM>.

Software and data used to practice embodiments can be stored on such portable computer readable storage media and can be loaded onto persistent storage <NUM> via I/O interface(s) <NUM>. I/O interface(s) <NUM> may also connect to a display <NUM>. Display <NUM> provides a mechanism to display data to a user and may be, for example, a computer monitor.

The programs described herein are identified based upon the application for which they are implemented in a specific embodiment. However, it should be appreciated that any particular program nomenclature herein is used merely for convenience, and thus the embodiments should not be limited to use solely in any specific application identified and/or implied by such nomenclature.

The present embodiments may employ any number of any type of user interface (e.g., Graphical User Interface (GUI), command-line, prompt, etc.) for obtaining or providing information where the interface may include any information arranged in any fashion. The interface may include any number of any types of input or actuation mechanisms (e.g., buttons, icons, fields, boxes, links, etc.) disposed at any locations to enter/display information and initiate desired actions via any suitable input devices (e.g., mouse, keyboard, etc.). The interface screens may include any suitable actuators (e.g., links, tabs, etc.) to navigate between the screens in any fashion.

The environment of the present embodiments may include any number of computer or other processing systems (e.g., client or end-user systems, server systems, etc.) and databases or other repositories arranged in any desired fashion, where the present embodiments may be applied to any desired type of computing environment (e.g., cloud computing, client-server, network computing, mainframe, stand-alone systems, etc.). The computer or other processing systems employed by the present embodiments may be implemented by any number of any personal or other type of computer or processing system (e.g., embedded, desktop, laptop, PDA, mobile devices, etc.), and may include any commercially available operating system and any combination of commercially available and custom software (e.g., machine learning software, etc.). These systems may include any types of monitors and input devices (e.g., keyboard, mouse, voice recognition, etc.) to enter and/or view information.

Each of the elements described herein may couple to and/or interact with one another through interfaces and/or through any other suitable connection (wired or wireless) that provides a viable pathway for communications. Interconnections, interfaces, and variations thereof discussed herein may be utilized to provide connections among elements in a system and/or may be utilized to provide communications, interactions, operations, etc. among elements that may be directly or indirectly connected in the system. Any combination of interfaces can be provided for elements described herein in order to facilitate operations as discussed for various embodiments described herein.

The various functions of the computer or other processing systems may be distributed in any manner among any number of software and/or hardware modules or units, processing or computer systems and/or circuitry, where the computer or processing systems may be disposed locally or remotely of each other and communicate via any suitable communications medium (e.g., LAN, WAN, Intranet, Internet, hardwire, modem connection, wireless, etc.). For example, the functions of the present embodiments may be distributed in any manner among the various end-user/client and server systems, and/or any other intermediary processing devices. The software and/or algorithms described above and illustrated in the flow charts may be modified in any manner that accomplishes the functions described herein. In addition, the functions in the flow charts or description may be performed in any order that accomplishes a desired operation.

The software of the present embodiments may be available on a non-transitory computer useable medium (e.g., magnetic or optical mediums, magneto-optic mediums, floppy diskettes, CD-ROM, DVD, memory devices, etc.) of a stationary or portable program product apparatus or device for use with stand-alone systems or systems connected by a network or other communications medium.

The communication network may be implemented by any number of any type of communications network (e.g., LAN, WAN, Internet, Intranet, VPN, etc.). The computer or other processing systems of the present embodiments may include any conventional or other communications devices to communicate over the network via any conventional or other protocols. The computer or other processing systems may utilize any type of connection (e.g., wired, wireless, etc.) for access to the network. Local communication media may be implemented by any suitable communication media (e.g., local area network (LAN), hardwire, wireless link, Intranet, etc.).

The system may employ any number of any conventional or other databases, data stores or storage structures (e.g., files, databases, data structures, data or other repositories, etc.) to store information. The database system may be implemented by any number of any conventional or other databases, data stores or storage structures (e.g., files, databases, data structures, data or other repositories, etc.) to store information. The database system may be included within or coupled to the server and/or client systems. The database systems and/or storage structures may be remote from or local to the computer or other processing systems, and may store any desired data.

The embodiments presented may be in various forms, such as a system, a method, and/or a computer program product at any possible technical detail level of integration. The computer program product may include a computer readable storage medium (or media) having computer readable program instructions thereon for causing a processor to carry out aspects of presented herein.

Computer readable program instructions for carrying out operations of the present embodiments may be assembler instructions, instruction-set-architecture (ISA) instructions, machine instructions, machine dependent instructions, microcode, firmware instructions, state-setting data, configuration data for integrated circuitry, or either source code or object code written in any combination of one or more programming languages, including an object oriented programming language such as Python, C++, or the like, and procedural programming languages, such as the "C" programming language or similar programming languages. In some embodiments, electronic circuitry including, for example, programmable logic circuitry, field-programmable gate arrays (FPGA), or programmable logic arrays (PLA) may execute the computer readable program instructions by utilizing state information of the computer readable program instructions to personalize the electronic circuitry, in order to perform aspects presented herein.

Aspects of the present embodiments are described herein with reference to flowchart illustrations and/or block diagrams of methods, apparatus (systems), and computer program products according to the embodiments.

The flowchart and block diagrams in the figures illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to various embodiments. In some alternative implementations, the functions noted in the blocks may occur out of the order noted in the figures.

To summarize, in one form, a method is provided and includes ramping down a welding current, generated by a power source, that reaches a welding zone via a welding circuit; storing inductive energy from the welding circuit that is generated as a result of the ramping down to obtain stored energy; and selectively feeding the stored energy to the welding circuit.

The method may further include enabling newly-generated welding current, generated by the power source, to reach the welding zone while simultaneously feeding the stored energy to the welding circuit.

The ramping down the welding current may include opening a switch disposed between the power source and the welding zone.

The method may still further include enabling newly-generated welding current, generated by the power source, to reach the welding zone by closing the switch.

Storing inductive energy may include storing the inductive energy in a capacitor, and the method may include pre-charging the capacitor.

The method may still also include selectively feeding the stored energy to the welding circuit by operating a converter, such as a buck converter.

The method may also include ramping down the welding current synchronously with a fuse of a welding wire droplet in a short arc welding operating mode.

In one implementation, the method feeds approximately <NUM>% of the inductive energy back to the welding circuit.

In an implementation, selectively feeding the stored energy to the welding circuit includes controlling a switch to discharge a capacitor that stores the stored energy.

In another form an apparatus is provided. The apparatus includes a power source configured to deliver welding current to a welding zone via a welding circuit, a current brake disposed between the power source and the welding zone, and a braking energy recovery module configured to: ramp down the welding current, generated by the power source, that reaches the welding zone via the welding circuit, store inductive energy from the welding circuit that is generated as a result of the ramping down to obtain stored energy; and selectively feed the stored energy to the welding circuit.

In the apparatus the braking energy recovery module may be further configured to enable newly-generated welding current, generated by the power source, to reach the welding zone while simultaneously feeding the stored energy to the welding circuit.

In the apparatus, the braking energy recovery module may be further configured to ramp down the welding current, generated by the power source, by opening a switch disposed between the power source and the welding zone.

In the apparatus, the braking energy recovery module is further configured to enable newly-generated welding current, generated by the power source, to reach the welding zone by closing the switch.

In an embodiment, the braking energy recovery module may be further configured to store the inductive energy by storing the inductive energy in a capacitor.

In still another embodiment, the braking energy recovery module may be further configured to selectively feed the stored energy to the welding circuit by operating a buck converter.

In yet another form, one or more non-transitory computer-readable storage media are encoded with software comprising computer executable instructions and, when the software is executed, are operable to: ramp down a welding current, generated by a power source, that reaches a welding zone via a welding circuit, store inductive energy from the welding circuit that is generated as a result of the ramp down to obtain stored energy, and selectively feed the stored energy to the welding circuit.

The software may be further configured to enable newly-generated welding current, generated by the power source, to reach the welding zone while simultaneously feeding the stored energy to the welding circuit.

The software may also be further configured to ramp down the welding current, generated by the power source, that reaches the welding zone by opening a switch disposed between the power source and the welding zone.

The software may also be further configured to selectively feed the stored energy to the welding circuit by operating a buck converter.

Claim 1:
A short arc welding method comprising:
ramping down a welding current, generated by a power source (<NUM>), that reaches a welding zone (<NUM>) via a welding circuit; and
storing inductive energy from the welding circuit that is generated as a result of the ramping down to obtain stored energy; characterised in that the method further comprises:
selectively feeding the stored energy to the welding circuit.