Systems and methods for providing welding arc initiation and stabilization with reduced open-circuit voltage

Abstract

Systems and methods for providing welding-type arc initiation and stabilization with reduced open-circuit voltage are disclosed. An example welding-type power supply includes: a power conversion circuit system configured to convert input power into welding-type power; and a control circuit system configured to: control the power conversion circuit system to output a voltage pulse at a first voltage; determine whether the power conversion circuit system outputs current during the voltage pulse; control the power conversion circuit system to shut off the output or output a second voltage less than the first voltage in response to determining that a current less than a threshold output current exists during the voltage pulse; and control the power conversion circuit system to output the welding-type power in response to determining that the power conversion circuit system outputs at least a threshold output current during the voltage pulse.

Description

Background Technology

[0001] This disclosure generally relates to welding systems, and more specifically to systems and methods for providing welding arc initiation and stabilization with reduced open-circuit voltage. Summary of the Invention

[0002] Systems and methods for providing welding-type arc initiation and stabilization with reduced open-circuit voltage are disclosed, substantially as illustrated by at least one figure and described in conjunction with the at least one figure, as set forth more thoroughly in the claims. Attached Figure Description

[0003] Figure 1 This is a schematic diagram of an example welding system including a welding power supply configured to output welding power, based on various aspects of this disclosure.

[0004] Figure 2 It's a circuit diagram, showing... Figure 1 Example implementation of a power conversion circuit system.

[0005] Figure 3 It's a timing diagram, showing the relationship with... Figure 1 and Figure 2 Example control signals, output voltage, and output current associated with an example power conversion circuit system.

[0006] Figure 4A It's a waveform diagram, showing... Figure 1 and Figure 2 The power conversion circuit system outputs a voltage for a series of voltage pulses.

[0007] Figure 4B yes Figure 4A A more detailed waveform diagram of the example voltage pulse.

[0008] Figure 5 It is a waveform diagram showing the voltage and current during an example transition from a voltage pulse to output welding-type power.

[0009] Figure 6 It is a waveform diagram showing the voltage and current during an example transition from output welding-type power to output voltage pulses.

[0010] Figure 7 It's a flowchart illustrating example machine-readable instructions that can be generated by... Figure 1 The welded type power supply is used to control the power conversion circuit system to reduce the open-circuit voltage during open-circuit conditions.

[0011] Figure 8 It's a flowchart illustrating example machine-readable instructions that can be generated by... Figure 1 The welding power supply is used to control the power conversion circuit system to stabilize the arc during the welding process.

[0012] The accompanying drawings are not to scale. Where appropriate, the same or similar reference numerals are used in the drawings to refer to similar or identical elements. Detailed Implementation

[0013] Traditional welding power supplies (especially those utilizing the SMAW process) intermittently provide welding output when no welding arc is present and no welding process is occurring. Welding output may also be driven for certain periods in other processes such as GMAW, FCAW, and / or GTAW (e.g., when the torch trigger is pulled or the foot pedal is pressed), before and / or after the welding process. Driving the power supply circuitry to output welding power when no welding process is occurring results in significant energy waste.

[0014] Some equipment standards specify a maximum permissible average open-circuit voltage. For conventional power supplies configured to drive the output to comply with these equipment standards when welding is not in progress, the output must be below the specified open-circuit voltage. By lowering the open-circuit voltage, the power supply may have a reduced or delayed response when the operator wants to start welding and attempt to ignite the arc. A reduced or delayed response may make arc ignition more difficult and / or prevent the supply of the desired power during the initial stages of the welding process.

[0015] The disclosed example systems and methods improve arc initiation, providing a reduced average open-circuit voltage that conforms to applicable equipment standards and reducing power consumption during non-welding (or other welding-type process) periods. The example systems and methods output a series of voltage pulses (e.g., voltage pings) with a low open-circuit voltage, wherein the welding power supply output is driven on for a very short duration, followed by a rest period during which the welding power supply output is limited or cut off. During and / or immediately after the voltage pulses, the example systems and methods measure the output current and / or output voltage of the welding power supply. If the sensed output current and / or output voltage indicates the presence of an arc condition (e.g., welding-type circuit closed, arc initiation, etc.), the control circuitry of the welding power supply switches the welding power supply to a welding-type output state. In some examples, the control circuitry may implement one or more steps or stages of the arc initiation sequence, such as the “hot arc initiation” stage of a SMAW process.

[0016] In some examples, voltage pulses are repeated at certain intervals or repetition rates until arc ignition or the power supply is shut off. When arc ignition occurs, the disclosed examples stop the voltage pulses and control the output of the welding power supply to provide the desired or commanded welding current and / or voltage.

[0017] At the end of the welding process, this termination can be defined or identified as the loss of the welding arc for at least a threshold time period. This loss of arc can be detected by sensing that the output current has dropped below the threshold and / or the output voltage has exceeded the threshold for at least the threshold time period. For example, the loss of arc can be detected by sensing that the output current has dropped below 10 amps for more than 200 milliseconds (ms). In response to the loss of arc or the end of the welding process, the power supply switches back to outputting voltage pulses in the same or similar manner as before arc ignition (e.g., to detect the next arc ignition event).

[0018] The average open-circuit voltage (OCV) is a function of the voltage pulse duration, the voltage of the voltage pulses, the repetition rate, and the background voltage (e.g., the voltage between voltage pulses). By controlling the voltage pulse duration, the voltage of the voltage pulses, the repetition rate, and the background voltage, the disclosed systems and methods can control the average OCV and provide a reduced average OCV. In some examples, the voltage and duration of the voltage pulses have sufficient amplitude and duration such that when the electrode contacts the workpiece, a current will be induced and detected within the first few voltage pulses. The voltage amplitude during the voltage pulses can be selected to more easily induce current under less-than-ideal conditions, to be comparable to arc initiation at full OCV. With a sufficiently high repetition rate (e.g., 1 kHz), the duration of the delay between voltage pulses when the electrode contacts the workpiece will be short enough (e.g., 1 to 2 ms) that this delay will not be noticeable to the welding operator.

[0019] The disclosed systems and methods provide arc initiation with reduced delay and improved performance even at low OCVs under suboptimal welding conditions (such as when oxides or rust are present on the workpiece being welded, when welding is performed using certain types of electrodes, when the operator's skill level is low, and / or any other suboptimal welding conditions).

[0020] The disclosed example welding power supply includes: a power conversion circuit system configured to convert input power into welding power; and a control circuit system. The control circuit system is configured to: control the power conversion circuit system to output a voltage pulse at a first voltage; determine whether the power conversion circuit system outputs current during the voltage pulse; in response to determining that a current less than a threshold output current exists during the voltage pulse, control the power conversion circuit system to cut off the output or output a second voltage less than the first voltage; and in response to determining that the power conversion circuit system outputs at least a threshold output current during the voltage pulse, control the power conversion circuit system to output the welding power.

[0021] In some example welding power supplies, the control circuitry is configured to control the power conversion circuitry to repeat the voltage pulse at regular intervals until at least a threshold output current is detected during the voltage pulse. In some examples, the control circuitry is configured to control the power conversion circuitry to output welding power with a current higher than the setpoint current during the hot-start phase.

[0022] In some example welding power supplies, the control circuit system is configured to: monitor the output welding current during the output of welding power by the power conversion circuit system; and in response to determining that the output current is continuously less than a threshold current for at least a threshold duration, control the power conversion circuit system to reduce the output voltage and control the power conversion circuit system to output voltage pulses at regular intervals.

[0023] Some example welding power supplies further include a voltage sensor configured to measure the output voltage of the welding power, wherein the control circuitry is configured to: monitor the output voltage during the output of welding power by the power conversion circuitry; and, in response to determining that the output voltage is at least a threshold voltage for at least a threshold duration, control the power conversion circuitry to reduce the output voltage and control the power conversion circuitry to output voltage pulses at intervals.

[0024] In some examples, the voltage pulse duration is less than 50 microseconds. In some examples, the voltage pulse duration is less than 20 microseconds. In some example welding power supplies, the second voltage is selected such that the average open-circuit voltage is less than 12 volts. In some examples, the control circuitry is configured to control the power conversion circuitry to output the second voltage to reduce the average open-circuit voltage when arc welding is not occurring.

[0025] In some example welding power supplies, the welding power is the first voltage. In some examples, the control circuitry is configured to: monitor the output current of the welding power via a current sensor during the output of the welding power by the power conversion circuitry; and, in response to detecting that the output current is less than a threshold current, output a predetermined duty cycle sequence to one or more switching elements of the power conversion circuitry to cause the power conversion circuitry to output voltage pulses, thereby increasing the output current during the voltage pulses. In some examples, the power conversion circuitry includes a pulse circuitry and a welding power circuitry, and the control circuitry is configured to: control the pulse circuitry to output voltage pulses at the first voltage; and, in response to determining that there is no output current during the voltage pulses, control the power conversion circuitry to output the second voltage; and, in response to determining that the pulse circuitry outputs current during the voltage pulses, control the welding power circuitry to output the welding power.

[0026] Some example welding-type power supplies further include a current sensor configured to measure the output current from the power conversion circuit system, wherein the control circuit system is configured to determine, based on the measured output current, that an output current less than a threshold exists. Some example welding-type power supplies further include a voltage sensor configured to measure the output voltage from the power conversion circuit system, wherein the control circuit system is configured to determine, based on the measured output voltage, that an output current less than the threshold exists.

[0027] Some publicly disclosed examples of welding power supplies include: a power conversion circuit system configured to convert input power into welding power; a current sensor configured to measure the current of the welding power; and a control circuit system configured to: control one or more switching elements of the power conversion circuit system to output welding power having an output voltage based on the duty cycle of one or more switching elements of the power conversion circuit system; monitor the output current of the welding power; and when the output current is less than a first threshold current, output a predetermined duty cycle sequence to the one or more switching elements of the power conversion circuit system to cause the power conversion circuit system to output a voltage pulse thereby increasing the output current during the voltage pulse.

[0028] In some examples, the control circuitry is configured to output a predetermined duty cycle sequence to the plurality of switching elements of the power conversion circuitry, causing the power conversion circuitry to repeat voltage pulses at intervals when the output current is less than a threshold current. In some example welding-type power supplies, the control circuitry is configured to: in response to determining that the output current is continuously less than a second threshold current for at least a threshold duration, control the power conversion circuitry to reduce the output voltage to less than a second voltage, and control the power conversion circuitry to output voltage pulses at intervals.

[0029] Some example welding power supplies further include a voltage sensor configured to measure the output voltage of the welding power, wherein the control circuitry is configured to: monitor the output voltage during the output of welding power by the power conversion circuitry; and, in response to determining that the output voltage remains at least a threshold voltage for at least a threshold duration, control the power conversion circuitry to reduce the output voltage to less than a second voltage, and control the power conversion circuitry to output voltage pulses at intervals. In some examples, the second voltage is selected such that the average open-circuit voltage is less than 12 volts. In some examples, the duration of the current pulses is less than 50 microseconds. In some examples, the duration of the current pulses is less than 20 microseconds.

[0030] In some example welding power supplies, the one or more switching devices include a plurality of switching devices configured to control the welding output. The control circuitry is configured to control the plurality of switching devices via pulse width modulation signals having corresponding duty cycles, and the control circuitry is configured to control the power conversion circuitry to output a first current pulse by controlling the plurality of switching devices with a 100% duty cycle. In some example welding power supplies, the control circuitry is configured to control the one or more switching elements of the power conversion circuitry based on a control cycle to output welding power with the output voltage, and outside the control cycle, output a predetermined duty cycle sequence to the one or more switching elements of the power conversion circuitry.

[0031] Although the examples disclosed below are discussed with reference to shielded metal arc welding (SMAW, also known as electrode welding), the example systems and methods disclosed can be used with any type of arc welding process, including but not limited to gas tungsten inert welding (GTAW, also known as TIG welding), gas metal arc welding (GMAW), flux-cored wire arc welding (FCAW), plasma cutting, and / or any other arc process. The amplitude, duration, and / or repetition rate can be selected based on the specific type of welding process used.

[0032] In addition to outputting voltage pulses to reduce the average open-circuit voltage, or as an alternative, the disclosed systems and methods also output voltage pulses to improve the stability of the welding arc during welding processes. For example, during a GMAW process, the output welding current may drop to very low levels (e.g., less than 10 to 20 amperes). If the current drops too low, the arc may become unstable and extinguish. Some example systems and methods apply a sequence of voltage pulses to the output of the welding power supply 102 during low-current welding conditions to assist the current and provide at least a predetermined minimum current to stabilize the welding arc. The duration and repetition rate of the voltage pulses can be adjusted according to specific welding conditions (such as electrode size and type, shielding gas), preset welding conditions (such as voltage and / or current, actual output current, actual output voltage), and / or any other welding conditions.

[0033] As used herein, "power conversion circuit system" and / or "power conversion circuit" refers to a circuit system and / or electrical component that converts electricity from one or more first forms (e.g., electricity output from a generator) into one or more second forms having any combination of voltage, current, frequency, and / or response characteristics. A power conversion circuit system may include a power limiting circuit system, an output selection circuit system, a measurement and / or control circuit system, and / or any other circuitry for providing appropriate characteristics.

[0034] As used herein, the terms “first” and “second” can be used to enumerate different parts or elements of the same type and do not necessarily imply any particular order. For example, although in some examples, the first time occurs before the second time within a period of time, the terms “first time” and “second time” do not imply any particular order in which the first time or the second time occurs relative to each other within that period of time.

[0035] As used herein, the term "welding system" includes any device capable of supplying power for welding, plasma cutting, induction heating, air-blown carbon arc cutting (e.g., CAC-A) and / or hot wire welding / preheating (including laser welding and laser cladding), including inverters, converters, choppers, resonant power supplies, quasi-resonant power supplies, etc., and associated control circuitry and other auxiliary circuitry.

[0036] As used herein, the term "welding power" refers to power suitable for welding, plasma cutting, induction heating, CAC-A and / or hot wire welding / preheating (including laser welding and laser cladding). As used herein, the terms "welding power supply" and / or "power supply" refer to any device capable of supplying power to welding, plasma cutting, induction heating, CAC-A and / or hot wire welding / preheating (including laser welding and laser cladding) when power is applied thereto, including but not limited to inverters, converters, resonant power supplies, quasi-resonant power supplies, and the control circuitry and other auxiliary circuitry associated therewith.

[0037] As used herein, “circuit” or “circuit system” includes any analog and / or digital components, power and / or control elements (such as microprocessors, digital signal processors (DSPs), software, etc.), discrete and / or integrated components, or multiple parts and / or combinations thereof.

[0038] As used herein, the terms “control circuit,” “control circuit system,” and / or “controller” can include digital and / or analog circuit systems, discrete and / or integrated circuit systems, microprocessors, digital signal processors (DSPs), and / or other logic circuit systems and / or associated software, hardware, and / or firmware. Control circuitry or control circuit systems may reside on one or more circuit boards that form part or all of a controller and are used to control the soldering process, devices such as power supplies or wire feeders, and / or any other type of soldering-related system.

[0039] As used herein, the term "memory" includes volatile and non-volatile memory devices and / or other storage devices.

[0040] As used herein, the terms “torch,” “welding torch,” “welding tool,” or “welding instrument” refer to a device configured to be manipulated to perform welding-related tasks and may include handheld welding torches, robotic welding torches, welding guns, scraping tools, cutting tools, or other devices for generating a welding arc.

[0041] As used herein, the terms “welding mode,” “welding process,” “welding type process,” or “welding operation” refer to the type of process or output used, such as current-controlled (CC), voltage-controlled (CV), pulse-modulated gas metal arc welding (GMAW), flux-cored wire arc welding (FCAW), gas tungsten inert gas welding (GTAW, e.g., TIG), metal shielded arc welding (SMAW), spraying, short-circuiting, CAC-A, scraping process, cutting process, and / or any other type of welding process.

[0042] As used herein, the term "setpoint" refers to a target, such as a voltage target or a current target, under which the welding-type power will be output by the control power conversion circuit system.

[0043] Now turn to the attached diagram. Figure 1 This is a block diagram of an example welding system 100 having a welding power supply 102 and a welding torch 106. The welding system 100 supplies power to welding applications, controls them, and / or supplies them with consumables. Figure 1 In the example, power supply 102 directly supplies welding-type output power to welding torch 106. Welding torch 106 is configured for SMAW, GTAW, GMAW, or FCAW processes, and can be used to perform welding processes including DC welding-type current.

[0044] Power supply 102 (e.g., from an AC grid, engine / generator set, battery, or other energy generation or storage device, or a combination thereof) receives main power 108, regulates the main power, and provides output power to one or more welding devices as required by system 100. Main power 108 can be supplied from a location remote from the site (e.g., the main power can be sourced from the grid). Power supply 102 includes a power conversion circuit system 110, which may include transformers, rectifiers, switches, etc., capable of converting AC input power into DC output power as required by system 100 (e.g., a specific welding process and scheme). Power conversion circuit system 110 converts the input power (e.g., main power 108) into welding-type power based on a target ampere number (e.g., welding current setpoint) and outputs the welding-type power via a welding circuit including welding cable 126. Welding cable 126 couples power conversion circuit system 110 to welding torch 106.

[0045] Power supply 102 includes a control circuitry system 112 for controlling the operation of power supply 102. Power supply 102 also includes a user interface 114. The control circuitry system 112 receives input from the user interface 114, through which a user can select processes and / or input desired parameters (e.g., voltage, current, frequency, peak pulse current time, peak pulse current percentage, background pulse current time, background pulse current percentage, AC waveform type, AC balance, soldering circuit inductance, etc.). The user interface 114 can receive input using one or more input devices 115, such as via a keypad, keyboard, physical buttons, switches, knobs, mouse, keypad, touchscreen (e.g., software buttons), voice activation system, wireless devices, etc. Furthermore, the control circuitry system 112 controls operating parameters based on user input and other current operating parameters. Specifically, the user interface 114 may include a display 116 for presenting, displaying, or indicating information to the operator.

[0046] The control circuitry system 112 may also include an interface circuitry system for transmitting data to other devices within the system 100. For example, in some cases, the power supply 102 communicates with a remote interface via a wireless or wired connection, such as by transmitting data over a network (e.g., Ethernet, 10baseT, 10base100, etc.) using a network interface controller (NIC). In some examples, the control circuitry system 112 communicates with the remote interface via soldered circuitry.

[0047] The control circuitry system 112 includes at least one controller or processor 120 that controls the operation of the power supply 102. The control circuitry system 112 receives and processes multiple inputs associated with the performance and requirements of the system 100. The processor 120 may include one or more microprocessors, such as one or more "general-purpose" microprocessors, one or more special-purpose microprocessors and / or ASICs, and / or any other type of processing device. For example, the processor 120 may include one or more digital signal processors (DSPs).

[0048] Example control circuitry system 112 includes one or more storage devices 123 and one or more memory devices 124. The storage devices 123 (e.g., non-volatile storage devices) may include ROM, flash memory, hard disk drives and / or any other suitable optical storage media, magnetic storage media and / or solid-state storage media and / or combinations thereof. Storage devices 123 store data (e.g., data corresponding to a welding application), instructions (e.g., software or firmware for performing a welding process), and / or any other suitable data. Examples of data stored for welding applications include predetermined relationships between frequency and ampere values, such as one or more lookup tables, as described in more detail below.

[0049] Memory device 124 may include volatile memory (such as random access memory (RAM)) and / or non-volatile memory (such as read-only memory (ROM)). Memory device 124 and / or (multiple) storage devices 123 may store various information and may be used for various purposes. For example, memory device 124 and / or (multiple) storage devices 123 may store processor-executable instructions 125 (e.g., firmware or software) for execution by processor 120. In addition, storage devices 123 and / or memory device 124 may store one or more control schemes for various welding processes, along with associated settings and parameters.

[0050] In some examples, gas supplier 128 provides a shielding gas, such as argon, helium, carbon dioxide, etc., depending on the welding application. The shielding gas flows to valve 130, which controls the gas flow and, if necessary, can be selected to allow adjustment or regulation of the amount of gas supplied to the welding application. Valve 130 can be opened, closed, or otherwise operated by control circuitry system 112 to allow, prohibit, or control the flow of gas (e.g., shielding gas) through valve 130. The shielding gas exits valve 130 and flows via cable 138 (in some embodiments, which may be integrated with the welding power output) to welding torch 106, thereby providing shielding gas to the welding application. In some examples, welding system 100 does not include gas supplier 128, valve 130, and / or cable 138.

[0051] Welding torch 106 delivers welding power and / or shielding gas for welding applications. Welding torch 106 is used to establish a welding arc between welding torch 106 and workpiece 146. Working cable 148 couples workpiece 146 to power supply 102 (e.g., to power conversion circuit system 110) to provide a return path for welding current (e.g., as part of a welding circuit). Example working cable 148 may be attached to and / or detached from power supply 102 for easy replacement of working cable 148. Working cable 148 may be terminated with clamp 150 (or another power connection device) that couples power supply 102 to workpiece 146.

[0052] In some examples, the welding torch 106 includes or is connected to one or more sensors 147 to monitor one or more welding parameters (e.g., power, voltage, current, inductance, impedance, etc.) during the welding process, thereby notifying the control circuitry 112.

[0053] Example control circuitry 112 controls power conversion circuitry 110 to output a low open-circuit voltage (e.g., 0V, less than 1V, etc.) with a series of voltage pulses (e.g., short voltage pulses), wherein the output of power conversion circuitry 110 is turned on for a short duration, followed by a rest period during which the output of power conversion circuitry 110 is limited or turned off. During and / or immediately after the voltage pulses, control circuitry 112 (e.g., via current sensor 118) determines or measures the output current and / or (e.g., via voltage sensor 119) the output voltage. If the sensed output current and / or output voltage indicates the presence of an arcing condition (e.g., welding circuit closed, arcing, etc.), control circuitry 112 switches power conversion circuitry 110 to a welding output state. In some examples, control circuitry 112 may implement one or more steps or stages of an arc initiation sequence, such as the “hot start” stage of a SMAW process.

[0054] The “hot start” phase of the SMAW process can include a phase between the arc initiation and arc stabilization phases, in which control variables (e.g., current) are set to be higher than the same variables in the steady-state phase.

[0055] In some examples, voltage pulses are repeated at certain intervals or repetition rates until arc ignition or the power supply is shut off. When arc ignition occurs, control circuitry 112 stops the voltage pulses and controls the output of power conversion circuitry 110 to provide the desired or commanded welding current and / or voltage.

[0056] Figure 1The example power conversion circuit system 110 includes a welding-type power circuit system 132 and a pulse circuit system 134. The welding-type power circuit system 132 is configured to convert input power (e.g., main power 108) into welding-type power. The control circuit system 112 can control the welding-type power circuit system 132 based on specified parameters such as current and voltage, which can be configured via a user interface 114 (e.g., via input devices 115). When welding-type power is not needed (e.g., when no welding process is occurring), the control circuit system 112 can disconnect the welding-type power circuit system 132 to reduce the open-circuit voltage between the welding torch 106 and the workpiece 146.

[0057] Example pulse circuit system 134 is configured (e.g., in parallel with the welding output provided by welding-type power circuit system 132) to provide voltage pulses to the output of welding-type power supply 102. For example, control circuit system 112 can enable or disable pulse circuit system 134 to output voltage pulses at intervals while monitoring the output of pulse circuit system 134 to determine if current is flowing. Example pulse circuit system 134 may include switches for selectively coupling pulse circuit system 134 to input power and / or selectively coupling pulse circuit system 134 to output terminals to enable the output of voltage pulses. Pulse circuit system 134 may also include energy storage devices, power converter circuitry for outputting a desired voltage, and / or any other circuitry configured to selectively output voltage pulses. Control circuit system 112 can control the operation of pulse circuit system 134, or can control the connection and disconnection of the freely operating pulse circuit system 134 with the input and / or output terminals of welding-type power supply 102.

[0058] The pulse circuit system 134 can output a voltage pulse with an amplitude greater than the upper voltage limit of the welding-type power circuit system 132. The pulse circuit system 134 can be configured with sufficient capacity or energy storage to provide an initial current, enabling the control circuit system 112 to detect this current and respond by activating the welding-type power circuit system 132 and controlling it to output welding-type power. The higher voltage amplitude of the exemplary embodiment of the pulse circuit system 134 can advantageously aid in the detection of the initial current, particularly for certain electrode types and / or suboptimal welding conditions.

[0059] In some examples, the pulse circuit system 134 may be implemented external to the power conversion circuit system 110 and / or external to the power supply 102, and coupled to the control circuit system 112 via a communication connector or port. However, in some examples, the pulse circuit system 134 is omitted, and the control circuit system 112 controls the soldering power circuit system 132 to output both soldering power and voltage pulses, as described in more detail below. For example, the control circuit system 112 may implement the voltage pulse by briefly enabling the output of the soldering power circuit system 132 to output a voltage pulse.

[0060] Figure 2 It's a circuit diagram, showing... Figure 1 Example embodiments of power conversion circuit system 110 and / or welded power circuit system 132. Example power conversion circuit system 110 includes rectifier circuit 202, pre-regulator circuit 204, switch-mode power supply circuit 206, and output circuit 208. Example power conversion circuit system 110 receives input power 210 (e.g., ...). Figure 1 The main power 108) and the input power 210 are converted into welding type power output 212.

[0061] The rectifier circuit 202 receives input power 210 (e.g., AC input power) and rectifies the input power 210 to output DC power to the pre-regulator circuit 204. The pre-regulator circuit 204 regulates and / or corrects the power factor of the DC power and boosts the rectified DC power to output the regulated DC bus voltage to the switch-mode power supply circuit 206.

[0062] Figure 2 The example switch-mode power supply circuit 206 is a dual forward converter topology configured to receive a regulated DC bus from a pre-regulator circuit 204 and output high-current soldering-type output power. The switch-mode power supply circuit 206 includes a first forward converter 214 and a second forward converter 220. The first forward converter has transistors 216a and 216b controlled by a first pulse-width modulation (PWM) signal 218, and the second forward converter has transistors 222a and 222b controlled by a second PWM signal 224.

[0063] Both the example pre-regulator circuit 204 and the switch-mode power supply circuit 206 are controlled by the control circuit system 112. Specifically, the example control circuit system 112 outputs PWM signals 218, 224 and a third PWM signal 226 to control the transistor 228 of the pre-regulator circuit 204.

[0064] As mentioned earlier, during SMAW and / or GTAW welding operations, conventional power supplies continue to output voltage so that they are ready to supply welding power to the welding torch 106 when the operator attempts to trigger the arc. However, conventional power supplies will output a relatively high open-circuit voltage in the absence of an arc.

[0065] In order to reduce the open-circuit voltage to below a threshold voltage, example control circuit system 112 controls power conversion circuit system 110 to reduce the output voltage of output power 212 in the absence of an electric arc and output a series of voltage pulses to monitor a condition in which welding-type power should be output to maintain the electric arc.

[0066] Figure 3 This is sequence diagram 300, which shows the relationship with... Figure 1 and Figure 2 Example control signals 302, 304, 306, output voltage 308, and output current 310 are associated with the example power conversion circuit system 112. Example control signal 302 represents PWM signal 218, control signal 304 represents PWM signal 224, and control signal 306 represents a combination of PWM signals 218 and 224. Output voltage 308 and output current 310 represent solder-type output 212.

[0067] Example timing diagram 300 begins with no welding-type output. For example, control circuitry 112 can cut off the welding-type power output by controlling PWM signals 302, 304 to have a 0% duty cycle. In some other examples, control circuitry 112 can control the power conversion circuitry 112 to reduce its output by controlling PWM signals 302, 304 to correspond to a desired reduced output (which can be specified as being less than a threshold voltage). In some examples, the reduced output is selected such that the average open-circuit voltage is less than a threshold average voltage when voltage pulses are considered. Example threshold average voltages can be 35V, 12V, 9V, 5V, 1V (a voltage that cannot trigger an arc) and / or any other desired threshold average voltage.

[0068] During the first time period 312 shown in timing diagram 300, control circuitry 112 controls power conversion circuitry to output voltage pulse 314 via PWM signals 302 and 304, thereby increasing output voltage 308 (e.g., the output voltage of output 212). During voltage pulse 314, control circuitry 112 monitors welding-type output 212 to determine if at least a threshold output is present. For example, control circuitry 112 may use a current sensor (e.g., Figure 1 The current sensor 118) and / or voltage sensor (e.g., Figure 1A voltage sensor 119 is used to monitor the output 212. The example combination of output PWM pulses 308 will generate voltage pulses with a duration of approximately 15 to 20 μs, which may include the time for the output filter capacitor to discharge.

[0069] In some examples, the duty cycle of the combined PWM signal 306 is at least 90% during voltage pulses 314 and 320. However, any duty cycle of the combined PWM signal 306 that is capable of outputting at least the threshold current can be used.

[0070] The threshold output can correspond to a short circuit between the welding torch 106 (e.g., an electrode coupled to the welding torch 106) and the workpiece 146, which closes the welding circuit and allows current to flow. In some examples, the threshold output is any output current. In other examples, the threshold output is any current because if the welding circuit is open, no current will flow during the voltage pulse. In some examples, the control circuitry 112 can determine that at least a threshold current is being output based on (e.g., via voltage sensor 119) a voltage that has not reached at least a threshold voltage.

[0071] Because the soldering circuit is incomplete during the first time period 312 (e.g., current 310 does not increase), the example control circuit system 112 controls the power conversion circuit system to reduce or cut off the output power 212 during the time interval 316. When the time interval 316 expires and during the second pulse period 318, the control circuit system 112 controls the power conversion circuit system 110 to output another voltage pulse 320 in a manner similar to or the same as the output voltage pulse 314.

[0072] During voltage pulse 320, the example welding torch 106 makes electrical contact with the workpiece 146, causing the power conversion circuit system 110 to output at least a threshold output current driven by voltage pulse 320. Control circuit system 112 (e.g., via current sensor 118 and / or voltage sensor 119) detects the increase in current and, at time period 322, switches to controlling the power conversion circuit system 110 to output welding-type power at welding-type output 212 according to parameter setpoints (e.g., current setpoint, voltage setpoint, etc.). In some examples, such as when a hot-start mode is enabled for a SMAW process, the example control circuit system 112 switches to hot-start mode in response to detecting current during voltage pulse 320 before transitioning to a steady-state welding process.

[0073] Figure 4A It is waveform diagram 400, which shows... Figure 1 and Figure 2 The power conversion circuit system 110 outputs voltages for a series of voltage pulses 402, 404, 406, and 408. For example... Figure 4AAs shown, the control circuit system 112 can control the power conversion circuit system 110 to output voltage pulses at regular intervals, while simultaneously reducing the output voltage between pulses (e.g., cutting off the output or outputting a lower voltage). Therefore, Figure 1 The example power supply 102 provides a lower average open-circuit voltage, which reduces the power consumption of the power supply 102 when it is not performing a welding process.

[0074] A set of example voltage pulses 402, 404, 406, and 408 can each have a duration of 10 to 20 microseconds (μs) and an interval of approximately 1 millisecond (e.g., a repetition rate of approximately 1 kHz). However, other pulse durations, interval durations, and / or repetition rates may also be used.

[0075] Figure 4B yes Figure 4A A more detailed waveform diagram of the example voltage pulse 402 is shown below. For this example voltage pulse 402, a PWM signal 224 is applied with a 45% duty cycle or for a duration of 4.5 μs, followed by a PWM signal 218 with a 45% duty cycle or for a duration of 4.5 μs, and finally a PWM signal 224 with a reduced PWM duty cycle of 22.5% or for a duration of 2.25 μs. In some examples, the control circuitry 112 may adjust the PWM value sequence used to generate the voltage pulse 402 to provide more or less energy or voltage in the voltage pulse 402. This voltage pulse sequence may be adjusted based on one or more factors, such as electrode type, welding parameters, DC bus voltage feeding the switch-mode power supply circuit 206, whether a sleep (e.g., idle) mode is activated, voltage pulse repetition rate, and / or any other factors.

[0076] Figure 5 Waveform 500 shows... Figure 2 The output power 212 shows the output voltage 502 and output current 504 during an example transition from a voltage pulse to welding-type output power. Example waveform diagram 500 illustrates this transition. Figure 3 The example demonstrates similar detection and conversion of welding output. During the first time period 506, the example control circuit system 112 controls the power conversion circuit system 110 to output voltage pulses, such as when the operator has brought the welding electrode and welding torch 106 into contact with the workpiece 146 to initiate the welding process.

[0077] During the first time period 506 and / or the second time period 508, the example control circuit system 112 identifies at least a threshold output current generated by a voltage pulse. In response to the detection of the output current, the control circuit system 112 initiates a transition to a welding-type process in the third time period 510 and controls the power conversion circuit system 110 to output welding-type power.

[0078] Figure 6 Waveform 600 shows the output voltage 602 and output current 604 during an example transition from output welding-type power to output voltage pulses. When the arc is extinguished and an open-circuit voltage exists between the welding torch 106 and the workpiece 146, the output voltage 602 and output current 604 indicate the end of the welding process.

[0079] During the first time period 606, the control circuit system 112 controls the power conversion circuit system 110 based on parameters and / or variables of the ongoing welding process. At the end of the first time period 606, the arc is extinguished, and the welding power supply 102 continues to execute the control cycle to control the power conversion circuit system 110 during the second time period 608. Example: The duration of the second time period 608 is equal to a threshold duration. During the second time period 608, the control circuit system 112 monitors the output voltage 602 and / or output current 604 to determine whether the welding process has ended or whether the arc has been reignited. Example: The threshold duration can be from 200 ms to 400 ms, but any duration can be used.

[0080] When the arc has been extinguished (e.g., the output voltage 602 is at least the threshold voltage and / or the output current 604 is less than the threshold current) for at least the threshold duration (e.g., the duration of the second time period 608), the control circuit system 112 initiates a series of voltage pulses during the time period 610, these voltage pulses being... Figure 3 , Figure 4A and Figure 4B The voltage pulses 314, 320, 402 to 408 are similar or identical. For example, the control circuit system 112 can control PWM signals 218 and 224 to cause the power conversion circuit system 110 to output voltage pulses at regular intervals.

[0081] Figure 7 It's a flowchart that shows what can be done by... Figure 1 The welded power supply 102 executes example machine-readable instructions 700, which are used to control the power conversion circuit system 110 to reduce the open-circuit voltage during open-circuit conditions. Example control circuit system 112 (e.g., processors 120) may execute instructions 700 during the initialization of the power supply 102.

[0082] At block 702, control circuitry 112 controls power conversion circuitry 110 to shut down its output or output a low voltage. For example, control circuitry 112 may output PWM signals 218, 224 to have a low or 0% duty cycle, and / or to make the average output voltage less than a threshold voltage. An example threshold average output voltage is 12V, but other thresholds may be used.

[0083] At block 704, control circuitry 112 determines whether the interval timer has expired. For example, control circuitry 112 may output pulses at regular intervals determined by the interval timer. If the interval timer has not expired (block 704), control returns to block 702.

[0084] When the interval timer expires (box 704), at box 706, control circuit system 112 controls power conversion circuit system 110 to output a voltage pulse and reset the interval timer. For example, control circuit system 112 can output PWM signals 218, 224 to increase the output voltage, such as... Figure 3 , Figure 4A and Figure 4B The pulses are 314, 320, 402 to 408.

[0085] At block 708, control circuitry 112 determines whether an arc and / or current is detected during the voltage pulse. For example, control circuitry 112 may determine whether at least a threshold output current and / or output voltage is detected via current sensor 118 as being less than a threshold voltage. If no arc or current is detected during the voltage pulse (block 708), control returns to block 702.

[0086] If an arc and / or current is detected during a voltage pulse (box 708), then at box 710, control circuitry 112 controls power conversion circuitry 110 to initiate a warm-start phase. For example, the warm-start phase may include an increased current relative to a current parameter. In some examples, box 710 may be omitted if the warm-start mode is disabled and / or a GTAW process is used.

[0087] At block 712, control circuit system 112 controls power conversion circuit system 110 to output welding power based on welding parameters. For example, control circuit system 112 may output PWM signals 218, 224, 226 to output welding power according to parameters selected for the welding process (e.g., current, voltage, etc.).

[0088] At block 714, control circuitry 112 determines whether an electric arc exists. For example, control circuitry 112 may determine whether the current measured by current sensor 118 is less than a threshold current indicating arc extinguishing and / or whether the voltage measured by voltage sensor 119 is greater than a threshold voltage. If an arc still exists (block 714), control returns to block 712 to continue controlling power conversion circuitry 110.

[0089] When the electric arc is no longer present (box 714), at box 716, control circuit system 112 resets the interval timer and returns control to box 702 to restart the output of voltage pulses at regular intervals. For example, control circuit system 112 can control power conversion circuit system 110 to switch from welding-type output to outputting lower open-circuit voltage and voltage pulses (as referenced above). Figure 6 (As shown).

[0090] Figure 8 It's a flowchart that shows what can be done by... Figure 1 The welding power supply executes example machine-readable instructions 800, which are used to control the power conversion circuit system to stabilize the electric arc during the welding process. Figure 8 Example instruction 800 can be derived from Figure 1 The control circuitry system 112 and / or (multiple) processors 120 execute, and may execute during the initialization of the power supply 102. (See above reference...) Figure 7 In addition to the disclosed output voltage pulse and reducing the average open-circuit voltage output by power supply 102, example instruction 800 also outputs a similar voltage pulse during the welding process when the output current is less than a threshold, in order to stabilize and / or maintain the arc.

[0091] At block 802, control circuitry 112 controls power conversion circuitry 110 to shut down its output or output a low voltage. For example, control circuitry 112 may output PWM signals 218, 224 to have a low or 0% duty cycle, and / or to make the average output voltage less than a threshold voltage. An example threshold average output voltage is 12V, but other thresholds may be used.

[0092] At block 804, control circuitry 112 determines whether the interval timer has expired. For example, control circuitry 112 may output pulses at regular intervals determined by the interval timer. If the interval timer has not expired (block 804), control returns to block 802.

[0093] When the interval timer expires (box 804), at box 806, control circuit system 112 controls power conversion circuit system 110 to output a voltage pulse and reset the interval timer. For example, control circuit system 112 can output PWM signals 218, 224 to increase the output voltage, such as... Figure 3 , Figure 4A and Figure 4B The pulses are 314, 320, 402 to 408.

[0094] At block 808, control circuitry 112 determines whether an arc and / or current is detected during the voltage pulse. For example, control circuitry 112 may determine whether at least a threshold output current and / or output voltage is detected via current sensor 118 as being less than a threshold voltage. If no arc or current is detected during the voltage pulse (block 808), control returns to block 802.

[0095] If an arc and / or current is detected during a voltage pulse (box 808), then at box 810, control circuitry 112 controls power conversion circuitry 110 to initiate a warm-start phase. For example, the warm-start phase may include an increased current relative to a current parameter. In some examples, box 810 may be omitted if the warm-start mode is disabled and / or a GTAW process is used.

[0096] At block 812, control circuit system 112 controls power conversion circuit system 110 to output welding power based on welding parameters. For example, control circuit system 112 may output PWM signals 218, 224, 226 to output welding power according to parameters selected for the welding process (e.g., current, voltage, etc.).

[0097] At block 814, control circuitry 112 determines whether an arc exists. For example, control circuitry 112 may determine whether the current measured by current sensor 118 is less than a threshold current indicating arc extinguishing and / or whether the voltage measured by voltage sensor 119 is greater than a threshold voltage. When the arc no longer exists (block 814), at block 816, control circuitry 112 resets the interval timer and returns control to block 802 to restart the output of voltage pulses at regular intervals. For example, control circuitry 112 may control power conversion circuitry 110 to switch from a welding-type output to outputting a lower open-circuit voltage and voltage pulses (as referenced above). Figure 6 (As shown).

[0098] If an arc still exists (box 814), the control circuitry 112 determines whether the output current is less than a threshold current. For example, the control circuitry 112 may compare the current measurement from the current sensor 118 with a threshold current indicating an increased risk of arc extinction. If the output current is less than the threshold current (box 818), at box 820, the control circuitry 112 activates a voltage pulse and determines whether an interval timer has expired. The interval timer used for the arc-stabilizing voltage pulse may be the same as or a different interval timer used to reduce the open-circuit voltage (e.g., box 804).

[0099] If the interval timer has expired (box 820), then at box 822, control circuitry 112 controls power conversion circuitry 110 to output a voltage pulse and reset the interval timer. For example, when control circuitry 112 has already output PWM signals 218, 224 to output current and / or voltage according to the welding process, example control circuitry 112 can increase the duty cycle of PWM signals 218, 224 during the voltage pulse to temporarily increase the voltage and / or current, thereby stabilizing and / or maintaining the arc. For example, although control circuitry 112 can control or output PWM signals 218, 224 according to a control loop, control circuitry 112 can also respond to a determination that the output current is less than a threshold by outputting a predetermined PWM signal sequence to cause power conversion circuitry 110 to output a voltage pulse outside the control loop. When the output current is less than the threshold, the predetermined PWM signal sequence can be repeated at certain intervals to increase the output current and / or stabilize the arc. The PWM signals 218, 224 used to output the stabilizing pulse can be similar to... Figure 3 , Figure 4A and Figure 4B PWM signals 302 and 304.

[0100] If the output current is not less than the threshold current (box 818), the interval timer has not expired (box 820), or after the output voltage pulse (box 822), control returns to box 812 to continue controlling the power conversion circuit system 110 according to the welding process.

[0101] This method and system can be implemented using hardware, software, and / or a combination of hardware and software. Typical combinations of hardware and software may include one or more application-specific integrated circuits (ASICs) and / or chips. Some implementations may include a non-transitory machine-readable (e.g., computer-readable) medium (e.g., flash memory, optical disc, magnetic disk, etc.) on which one or more lines of code executable by a machine are stored, thereby enabling the machine to perform the processes described herein. As used herein, the term "non-transitory machine-readable medium" is defined to include all types of machine-readable storage media and excludes propagated signals.

[0102] As used herein, the terms “circuit” and “circuit system” refer to physical electronic components (i.e., hardware) and any software and / or firmware (“code”) that can configure, be executed by, and / or otherwise associate with the hardware. As used herein, for example, a particular processor and memory may constitute a first “circuit” when executing a first line or more of code, and a second “circuit” when executing a second line or more of code. As used herein, “and / or” refers to any one or more items in a list connected by “and / or”. For example, “x and / or y” refers to any element in the three-element set {(x),(y),(x,y)}. In other words, “x and / or y” means “one or both of x and y”. As another example, “x, y, and / or z” refers to any element in the seven-element set {(x),(y),(z),(x,y),(x,z),(y,z),(x,y,z)}. In other words, “x, y, and / or z” means “one or more of x, y, and z”. As used herein, the term "exemplary" means used as a non-limiting example, instance, or example. As used herein, the terms "for example (eg,)" and "for instance (for example)" list one or more non-limiting examples, instances, or examples. As used herein, when a circuit system includes the hardware and code necessary to perform a certain function (if necessary), the circuit system is "capable of operating" to perform that function, regardless of whether the execution of that function is disabled or not enabled (e.g., through user-configurable settings, factory settings, etc.).

[0103] Although this method and / or system has been described with reference to certain embodiments, those skilled in the art will understand that various changes can be made and equivalents can be substituted without departing from the scope of this method and / or system. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from the scope of this disclosure. For example, the blocks and / or components of the disclosed examples can be combined, divided, rearranged, and / or otherwise modified. Therefore, this method and / or system is not limited to the specific embodiments disclosed. Instead, this method and / or system will include all embodiments that fall within the scope of the appended claims, both literally and according to the principle of equivalents.

Claims

1. A welded power supply, comprising: A power conversion circuit system configured to convert input power into a welding-type power output; as well as The control circuit system is configured to: When no welding arc is present, the power conversion circuit system is controlled to output a voltage pulse at a first voltage. When the welding arc is absent, determine whether the power conversion circuit system outputs output current during the voltage pulse; In response to the absence of the welding arc and the output current being less than a threshold output current during the voltage pulse, the power conversion circuit system is controlled to shut down the welding-type power output or output a second voltage less than the first voltage. and In response to determining that the power conversion circuit system outputs at least the threshold output current during the voltage pulse, the power conversion circuit system is controlled to begin outputting the welding-type power output.

2. The welded power supply as described in claim 1, wherein, The control circuit system is configured to control the power conversion circuit system to repeat the voltage pulse at regular intervals until at least the threshold output current is detected during the voltage pulse.

3. The welded power supply as described in claim 1, wherein, The control circuit system is configured to control the power conversion circuit system to output the welding-type power output with a current higher than the set point current during the hot start phase.

4. The welded power supply as described in claim 1, wherein, The control circuit system is configured as follows: During the output of the welding-type power by the power conversion circuit system, the output current is monitored; and In response to determining that the output current is less than a threshold current for at least a threshold duration, the power conversion circuit system is controlled to reduce the output voltage, and the power conversion circuit system is controlled to output the voltage pulses at certain intervals.

5. The welding-type power supply of claim 1, further comprising a voltage sensor configured to measure the output voltage of the welding-type power output, wherein, The control circuit system is configured as follows: During the output of the welding-type power by the power conversion circuit system, the output voltage is monitored; and In response to determining that the output voltage is at least a threshold voltage for at least a threshold duration, the power conversion circuit system is controlled to reduce the output voltage, and the power conversion circuit system is controlled to output the voltage pulses at certain intervals.

6. The welded power supply as described in claim 1, wherein, The duration of the voltage pulse is less than 50 microseconds.

7. The welded power supply as described in claim 6, wherein, The duration of the voltage pulse is less than 20 microseconds.

8. The welded power supply as described in claim 1, wherein, The second voltage is selected such that the average open-circuit voltage is less than 12 volts.

9. The welded power supply as described in claim 1, wherein, The control circuit system is configured to control the power conversion circuit system to output the second voltage in order to reduce the average open-circuit voltage when arc welding does not occur.

10. The welded power supply as claimed in claim 1, wherein, The welding-type power output includes the first voltage.

11. The welded power supply as claimed in claim 1, wherein, The control circuit system is configured as follows: During the output of the welding-type power by the power conversion circuit system, the output current of the welding-type power is monitored via a current sensor; and In response to detecting that the output current is less than a threshold current, a predetermined duty cycle sequence is output to one or more switching elements of the power conversion circuit system to cause the power conversion circuit system to output voltage pulses, thereby increasing the output current during the voltage pulses.

12. The welded power supply as claimed in claim 1, wherein, The power conversion circuit system includes a pulse circuit system and a welding-type power circuit system, and the control circuit system is configured as follows: The pulse circuit system is controlled to output the voltage pulse at the first voltage, and in response to determining that no output current exists during the voltage pulse, the power conversion circuit system is controlled to output the second voltage; and In response to determining that the pulse circuit system outputs current during the voltage pulse, the welding-type power circuit system is controlled to output the welding-type power output.

13. The welding-type power supply of claim 1, further comprising a current sensor configured to measure the output current from the power conversion circuit system, the control circuit system being configured to determine, based on the measured output current, that there exists a current less than the threshold output current.

14. The welding-type power supply of claim 1, further comprising a voltage sensor configured to measure an output voltage from the power conversion circuit system, the control circuit system being configured to determine, based on the measured output voltage, that there exists a current less than the threshold output current.

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