Welding power supply with dynamic current response

Abstract

Example welding power supply includes: a power conversion circuit configured to convert supplied power into welding current and output the welding current to at least one of a shielded metal arc welding (SMAW) electrode or a gouging torch; a voltage sensing circuit configured to measure the output voltage of the power conversion circuit; and a control circuit configured to: control the power conversion circuit using a current-controlled control loop based on a target current; control the target current based on the difference between a reference voltage and the output voltage when the output voltage is above a lower voltage limit; and control the welding current output by the power conversion circuit based on a first exponential relationship in response to detecting that the output voltage has dropped below the lower voltage limit.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Patent Application Serial No. 63 / 067,402, filed August 19, 2020, entitled “Welding Power Supply with Dynamic Current Response”. The entire contents of U.S. Patent Application No. 63 / 067,402 are expressly incorporated herein by reference. Background Technology

[0003] This disclosure generally relates to welding systems and, more specifically, to welding power supplies with dynamic current response.

[0004] In the past, the weld beading market and more specifically, pipe welding applications were primarily handled by DC generator welding machines. The inherent arc / welding characteristics of DC generators, determined by the machine's magnetic design, provide high-quality performance for pipe welding applications. The machine's response can be altered by selecting taps on the DC generator magnet and / or changing the resistance in the generator field circuit. Conventional electronically controlled inverter / high-frequency switching welding power supplies have failed to reproduce the welding characteristics of DC generators, which make them attractive for weld beading applications. While the ideal behavior is inherent in DC generators, this behavior is absent in traditional high-frequency switching welding power supplies. Summary of the Invention

[0005] A welding power supply with dynamic current response is disclosed, and is substantially as shown in at least one figure and described in conjunction with at least one figure. Attached Figure Description

[0006] Figure 1 This is a schematic diagram of an example welding power supply with adjustable current ramp rate according to various aspects of this disclosure.

[0007] Figure 2 For the reason Figure 1 The example welding power supply uses a chart of the example voltage-current relationship to provide welding power.

[0008] Figure 3 In response to the detected change in voltage relative to the reference voltage, by Figure 1 A graph illustrating an example current response implemented by a welding power supply.

[0009] Figure 4 In response to detecting that the output voltage has dropped below the lower voltage threshold, by Figure 1 A graph illustrating the example current response implemented by the welding power supply.

[0010] Figure 5 It shows what can be used to implement Figure 1Example user interface for a welding power supply to receive inputs for current, arc control, digging range, and / or slope parameters.

[0011] Figure 6A and Figure 6B Together they show that the representatives can be represented by Figure 1 A flowchart illustrating an example machine-readable instruction executed by a sample welding power supply to provide power for welding operations.

[0012] Figure 7 This is a flowchart representing an example machine-readable instruction, which can be derived from... Figure 1 Example welding power supply

[0013] The system controls the output current in response to a measured welding voltage decreasing below a threshold, for example, to clear a short circuit.

[0014] These figures are not necessarily drawn to scale. Where appropriate, similar or identical reference numerals are used to denote similar or identical parts. Detailed Implementation

[0015] The published examples provide methods for controlling the current response in a bond welding process. During bond welding, a short circuit occurs as molten metal droplets transfer from the tip of the welding electrode to the weld pool.

[0016] Conventionally, electronic / inverter welding power supplies control the welding current response during a short circuit by limiting the maximum short-circuit current that the power supply can provide. The maximum short-circuit current is controlled by the operator through so-called "dig" control or "arc force" control. Conventionally, "dig" control or "arc force" control is performed via a knob or other adjustment mechanism on the power supply's user interface. Conventionally, for inverter power supplies, the rate of current rise is constant and does not change with increasing or decreasing the arc force control setting (i.e., current limit).

[0017] Compared to conventional electronic / inverter welding power supplies, the disclosed examples more closely reproduce or mimic a portion of the response of a DC generator, allowing operators greater freedom in manipulating the welding process. In some examples, the disclosed systems and methods provide positive and negative drop control by adjusting the output target current of the current control loop based on the difference between the output voltage and the reference voltage in both positive and negative directions. Alternatively or additionally, the disclosed example systems and methods respond to a detected short circuit by increasing the current based on an exponential relationship, and / or respond to the clearing of a detected short circuit by decreasing the current based on an exponential relationship.

[0018] The disclosed examples enable the maintenance of a tighter arc length during welded pipe fittings without causing the welding electrode to stick to the pipe. This allows for greater flexibility across various welding conditions, fitting combinations, and other pipe fitting welding parameters. The disclosed examples also improve the speed and reliability of pipe fitting welding for the operator.

[0019] The terms “current” and “ampere” are used interchangeably here.

[0020] The disclosed welding power supply includes: a power conversion circuit configured to convert supplied power into welding current and output the welding current to at least one of a shielded metal arc welding (SMAW) electrode or a gouging torch; a voltage sensing circuit configured to measure the output voltage of the power conversion circuit; and a control circuit configured to control the power conversion circuit using a current-controlled control loop based on a target current; control the target current based on the difference between a reference voltage and the output voltage when the output voltage is above a lower voltage limit; and control the welding current output by the power conversion circuit based on a first exponential relationship in response to detecting that the output voltage has dropped below the lower voltage limit.

[0021] Some example welding power supplies further include an engine configured to drive a generator configured to supply power to a power conversion circuit. Some example welding power supplies further include a user interface configured to receive arc control parameters. In some example welding power supplies, the first exponential relationship is not based on the voltage error between the lower voltage limit and the output voltage.

[0022] In some example welding power supplies, the control circuitry is configured to control the welding current output by the power conversion circuitry based on a second exponential relationship and arc control parameters, in response to detecting that the output voltage has increased above a lower voltage limit. In some example welding power supplies, the second exponential relationship is not based on the voltage error between the lower voltage limit and the output voltage. In some example welding power supplies, at least one of the first or second exponential relationship includes a parabolic relationship with respect to time. In some example welding power supplies, the reference voltage is between 25V and 30V. In some example welding power supplies, the reference voltage is between 26V and 28V.

[0023] In some example welding power supplies, the control circuitry is configured to limit the welding current output based on an upper limit of the output current when the output voltage is below a lower voltage limit. Some example welding power supplies further include an input device configured to receive inputs, wherein arc control parameters are based on the inputs. In some example welding power supplies, the control circuitry is configured to control the welding current output by the power conversion circuit based on a current setpoint in response to detecting that the output voltage has increased above the lower voltage limit. In some example welding power supplies, the control circuitry is configured to: control the target welding current output by the power conversion circuit to have a first ampere / volt ratio when the output voltage is below a reference voltage; and to have a second ampere / volt ratio when the output voltage is above the reference voltage, the second ampere / volt ratio being different from the first ampere / volt ratio when the output voltage is below the reference voltage.

[0024] In some example welding power supplies, control circuitry is configured to, when controlling a power conversion circuit to output welding current based on a first exponential relationship, control the power conversion circuit to output welding current at an upper current limit in response to detecting that the output voltage has not increased to exceed a lower voltage limit within a threshold time period. Some example welding power supplies further include an input device configured to receive an input based on the upper current limit. Some example welding power supplies further include a voltage compensator configured to modify at least one of a lower voltage limit or a reference voltage based on a calculated voltage drop in at least one of the welding cable or the working cable.

[0025] In some example welding power supplies, the voltage sensing circuit is configured to measure the output voltage near the arc generated by the welding current. In some example welding power supplies, the lower voltage limit is approximately 19 volts.

[0026] Figure 1 This is a schematic diagram of an example welding power supply 100 with an adjustable current ramp rate. The example welding power supply 100 includes a power conversion circuit 102, a voltage sensing circuit 104, a control circuit 106, a voltage comparator 108, and a user interface 110. The example welding power supply 100 enables welders to perform shielded metal arc welding (SMAW), also known as "stick welding".

[0027] Figure 1The power conversion circuit 102 converts the main power 112 into welding-type power. Example power conversion circuit 102 may include a switch-mode power supply (or "inverter") topology. The main power 112 can be any suitable power source, such as mains power (e.g., trunk line), engine / generator power, and / or any combination of mains and engine power. The welding-type power has an output current based on a current-controlled loop. For example, the output current and / or welding voltage can be controlled based on a current setpoint and / or voltage setpoint selected via user interface 110. Power conversion circuit 102 outputs welding power to welding torch 114, such as a strip electrode holder. Welding torch 114 facilitates the establishment of a welding arc at workpiece 116.

[0028] Voltage sensing circuit 104 measures welding voltage. Welding voltage can refer to the output voltage of welding power supply 100 and / or the measured arc voltage. Figure 1 In one example, the voltage sensing circuit 104 samples or measures the welding voltage at the output terminal of the welding power supply 100. In some other examples, the voltage sensing circuit 104 may include sensing leads to measure the welding voltage at workpiece 116 and / or another location in the welding circuit.

[0029] The measured welding voltage is passed through an analog filter circuit. An example filter is a fourth-order filter with an angular frequency of 4 kHz. The output voltage feedback is provided to the control circuit 106. The voltage sensing circuit 104 and / or the voltage comparator 108 can implement an analog-to-digital converter to convert the voltage into a digital value. The control circuit 106 also filters the voltage feedback via software, firmware, and / or hardware. In some examples, the output voltage is compensated for the voltage drop that occurs on the welding cable.

[0030] Control circuit 106 uses a current control loop to control the output current and / or welding voltage output by power conversion circuit 102. User interface 110 may include user input devices to receive current parameters (e.g., output current setpoint). Control circuit 106 executes the current control loop based on output voltage information provided by voltage sensing circuit 104.

[0031] In some examples, the current control loop is implemented by a power conversion circuit 102. The voltage comparator 108 and the calculation of increasing and / or decreasing the current are implemented in software executed by a control circuit 106, which outputs a current command as an output to the current control loop implemented by the power conversion circuit 102. In some other examples, the current control loop is implemented in software executed by the control circuit 106, which controls the welding output of the power conversion circuit 102.

[0032] The voltage comparator 108 of the control circuit 106 compares the measured output voltage with one or more thresholds to determine a current control scheme. For example, when the voltage comparator 108 determines that the output voltage is between an upper and lower drop voltage limit (e.g., within the drop mode range), the control circuit 106 controls the power conversion circuit 102 to output welding current based on the difference between the output voltage and a reference voltage, by adjusting the target current of the current control loop relative to an ampere parameter or a current setpoint (e.g., a current set by the operator). For example, the control circuit 106 decreases the target output current when the output voltage increases and increases the target output current when the output voltage decreases. In some examples, the drop rate above the reference voltage (e.g., A / V) may differ from the drop rate below the reference voltage.

[0033] In some examples, the control circuit 106 can achieve a voltage range around the reference voltage (e.g., + / -0.5V, + / -1V, etc.) within which the control circuit 106 controls the target output current to the current setpoint.

[0034] When voltage comparator 108 determines that the output voltage is below a lower voltage limit, example control circuit 106 can control the output current using either a short-circuit mode or a digging mode. In digging mode, example control circuit 106 attempts to clear a short circuit between the welding electrode and workpiece 116. Example digging mode control techniques involve controlling one or more increasing ramp rates of the welding current output by power conversion circuit 102 and, in response to detecting that the output voltage has increased above a first lower voltage limit (e.g., the short circuit has been cleared and the arc has been re-established), controlling one or more decreasing ramp rates of the welding current output by power conversion circuit 102.

[0035] In some examples, control circuitry 106 selects arc control parameters based on arc control parameter inputs. Arc control parameter inputs can be received from user interface 110. For example, user interface 110 may include slope control inputs, arc control inputs, digging range inputs, and / or ampere parameter inputs to allow the user to select or adjust the arc control parameter inputs. In some examples, the input devices of user interface 110 mimic the tap selection and adjustment selection typically found on DC generator-type welding power supplies. Figure 1 In the example, the control circuit 106 executes a current control loop at a rate of at least 15 kHz.

[0036] In some examples, a single input parameter, such as an arc control parameter, can be used to adjust current control within both the dropout and digging ranges. For example, the arc control parameter can be adjusted between a "harder" (or equivalent) value and a "softer" (or equivalent) value. A harder arc control parameter can result in a higher ampere / volt ratio within the dropout range (e.g., control circuit 106 changes the target current by a larger amount per unit change in the output voltage) and a faster current increase within the digging range (e.g., one or more factors or constants in the exponential relationship can be adjusted). Conversely, a softer arc control parameter can result in a lower ampere / volt ratio within the dropout range (e.g., control circuit 106 changes the target current by a smaller amount per unit change in the output voltage) and a less rapid current increase within the digging range (e.g., one or more factors or constants in the exponential relationship can be adjusted). In other examples, the digging and dropout ranges can be controlled by different parameters, and / or one or both of the digging and dropout ranges can be fixed.

[0037] Control circuit 106 provides a dynamic current response to offer the welding operator superior arc behavior and improve the operator's control over the arc. As described in more detail below, control circuit 106 controls power conversion circuit 102 to control the output current based at least in part on the output voltage. When the output voltage is between a first upper voltage limit and a lower voltage limit, control circuit 106 controls the output welding current of power conversion circuit 102 based on the ampere parameter and the difference between the output voltage and reference voltage 216. In response to detecting that the output voltage has dropped below the lower voltage limit, control circuit 106 controls the gradually increasing welding current output by power conversion circuit 102, and in response to detecting that the output voltage has increased above the lower voltage limit 202, and when the short circuit has been cleared, controls the gradually decreasing welding current output by power conversion circuit 102.

[0038] When voltage comparator 108 determines that the output voltage is higher than a first voltage upper limit and lower than a second voltage upper limit, example control circuit 106 controls power conversion circuit 102 to output welding current based on a first voltage-ampere relationship (e.g., drop mode). Example voltage-ampere relationships that can be used in drop mode include: a corresponding voltage increase (e.g., a voltage higher than the first voltage upper limit) relative to a reference voltage, resulting in a decrease in current output (relative to the ampere parameter); and a corresponding voltage decrease (e.g., a voltage higher than the first voltage upper limit) relative to a reference voltage, resulting in an increase in current output (relative to the ampere parameter). Drop mode allows the welding operator to control the welding current input (and thus the heat input) by increasing the arc length (and therefore the arc voltage), and is particularly useful in downhill welding and / or off-site welding where control of the molten pool is required. An example reference voltage is 27V. However, other reference voltages between 26V and 28V can also be used. In some examples, the reference voltage can be between 25V and 30V.

[0039] Alternatively, the user interface 110 may allow selection of different stick-on welding operations, such as stick-on welding with 6010 electrodes, stick-on welding with 7018 electrodes, downhill pipe welding, etc., as inputs for arc control parameters. The control circuit 106 can select predetermined arc control parameters based on the selected stick-on welding operation.

[0040] In some examples, control circuit 106 can automatically identify the welding operation (e.g., electrode type) and select a predetermined current ramp rate based on the welding operation. Control circuit 106 can identify a specific electrode type (e.g., XX18, XX10, etc.) by, for example, reading markings attached to the electrode and / or observing welding characteristics, such as the frequency and / or duration of short-circuit events. For example, certain types of electrodes may cause short-circuit events to occur within a certain frequency range.

[0041] In some examples, control circuit 106 identifies welding data corresponding to output current, welding voltage, welding parameters input to control circuit 106, electrode size, and / or electrode type. Control circuit 106 can use the welding data to select current and / or arc control parameters. For example, a welder can specify the size and / or type of electrode for electrode bonding via user interface 110. In response, control circuit 106 identifies and selects a pre-adjusted current ramp rate for use with the specified electrode.

[0042] In some examples, control circuitry 106 stores welding data corresponding to welding operations (e.g., one or more previous welding operations performed by an operator). Control circuitry 106 can use the stored data as input to arc control parameters to select those parameters. For example, the stored welding data can indicate how many short circuits occurred within a given time period to determine the short circuit rate. Control circuitry 106 can then select the current ramp rate to adjust its response to the short circuit rate.

[0043] This section describes example types of arc control parameters. Control circuit 106 can use combinations of inputs to select arc control parameters.

[0044] Control circuit 106 executes a current control loop to control the output current. Figure 1 In the example, when the welding voltage corresponds to a short-circuit condition, the control circuit 106 increases the output current based on an exponential relationship. During the short circuit, the control circuit 106 can monitor the welding voltage to determine when the short circuit is about to be cleared. For example, when the welding voltage begins to increase (or increases for a certain number of consecutive samples), the control circuit 106 can stop increasing the current to reduce spatter caused by clearing the short circuit and reduce the output current based on the same or different exponential relationship until the output current reaches the current setpoint or other target current.

[0045] In some examples, the voltage sensing circuit 104 includes a voltage compensator 118 to estimate the arc voltage based on one or more inputs. To estimate the arc voltage, the voltage compensator 118 can estimate the voltage drop caused by the welding cable and / or the working cable, where the voltage drop will significantly affect the performance of the voltage threshold. Example inputs that can be used to estimate the arc voltage and / or voltage drop may include the output voltage, the welding cable resistance, the working cable resistance, the output current, and / or the output inductance.

[0046] Figure 2 Is using Figure 1 The example welding power supply 100 provides welding power, and the example voltage-current relationship 200 is shown in the graph. Figure 2 The example voltage-current relationship 200 can be defined as the output amperes set according to the output voltage, and includes three example voltage limits 202, 204, 206 and four voltage ranges 208, 210, 212, 214. The example voltage range 214 corresponds to the range of the power supply 100 within which the power supply 100 cannot output more output current at a given voltage.

[0047] When the output voltage is below the lower voltage limit 202, the control circuit 106 operates in digging mode within the voltage range 208. This reduces spatter and / or electrode degradation. Figure 1The control circuit 106 can use the excavation voltage range 208 to clear short-circuit events. See below for reference. Figure 4 An exemplary response of control circuit 106 to a measured output voltage below voltage lower limit 202 is described.

[0048] When the output voltage is between the lower voltage limit 202 and the lower voltage drop limit 204, the control circuit 106 operates in a current control mode (e.g., constant current mode) within the voltage range 210. Within the voltage range 210, the control circuit 106 uses a current control loop to control the power conversion circuit 102 to maintain a substantially constant current output. The control circuit 106 can maintain the current output substantially equal to the upper current limit of the drop mode (e.g., used in voltage range 212), which may be higher than the current parameter input through the user interface 110.

[0049] Example voltage range 210 is between 2 and 5 volts, or more specifically, about 3 volts. Example nominal lower voltage limit 202 is about 19V, and example nominal lower voltage limit 204 is between about 21V and about 24V, with boundary voltages included.

[0050] When the output voltage is between the lower drop voltage limit 204 and the upper drop voltage limit 206, the control circuit 106 operates in drop mode within the voltage range 212. In drop mode, the control circuit 106 controls the output current as a function of the difference between the output voltage and the reference voltage 216. When the output voltage increases above the reference voltage 216 (reaching the upper drop voltage limit 206), the control circuit 106 reduces the target current to decrease the output current. Conversely, when the output voltage drops below the reference voltage 216, the control circuit 106 increases the target current to increase the output current (down to the lower drop voltage limit 204). An example reference voltage 216 is approximately 27V. However, the reference voltage 216 can be between 25V and 30V. In some examples, the reference voltage 216 is between 26V and 28V. In some examples, the lower drop voltage limit 204, the upper drop voltage limit 206, and / or the reference voltage 216 can be configured based on selected ampere parameters (e.g., current setpoint). The nominal lower voltage limit 202, the lower drop voltage limit 204, the upper drop voltage limit 206, and / or the reference voltage 216 can be modified by the control circuit 106 and / or the voltage compensator 118 based on the detection of a significant voltage drop in the welding cable and / or the working cable. When the power conversion circuit 102 is operated in current control mode, a significant voltage drop results in an increase in the output voltage at the power conversion circuit 102.

[0051] Some parameters of the voltage-ampere relationship 200 can be modified by the welding operator. For example, the current in digging mode can be limited to restrict the output current used to clear a short circuit. Figure 2As shown, although any other limit between the ampere parameter and the maximum current output capability of the power conversion circuit 102 can be used, example limits 218a, 218b, 218c, and 218d can also be implemented. When the output current reaches the configured limits 218a, 218b, 218c, and 218d, the output current will not exceed the configured limits 218a, 218b, 218c, and 218d.

[0052] Example voltage limits 202, 204, 206 and / or reference voltage 216 can be modified via user interface 110 and / or via voltage compensator 118. For example, voltage limits 202-206 can be increased based on an increase in voltage drop across the welding and working cables. In some examples, voltage limits 202, 204 (e.g., voltage range 210) defining current control modes can be constrained to have a difference between 2 and 5 volts.

[0053] The slope of the drop mode can be adjusted to increase or decrease the current reduction per unit increase in output voltage. In some examples, the slope can be set between -1.5 amperes (A / V) and -3.0 A / V. The current variation is relative to an ampere parameter, which can also be adjusted to control the output current in current control mode (e.g., voltage range 210) (e.g., shifting the vertical portion of the voltage-ampere relationship 200 to the left or right within voltage range 210). In some examples, the slope between the reference voltage 216 and the upper limit of the drop voltage 206 differs from the slope between the reference voltage 216 and the lower limit of the drop voltage 204.

[0054] In some examples, the lower voltage drop limit 204 and the upper voltage drop limit 206 (e.g., limits of the voltage drop range 212) are adjusted in response to changes in the reference voltage 216, which may occur based on changes in ampere parameters, arc control parameters, and / or any other parameters. For example, the lower voltage drop limit 204 and the upper voltage drop limit 206 can be increased or decreased by the same amount as the change in the reference voltage 216 to keep the total voltage range of the drop mode 212 constant. In some examples, the lower voltage drop limit 204 may be reduced to be as low as the lower voltage limit 202 in response to changes in the reference voltage 216. Furthermore or alternatively, the slope in the upper voltage drop limit 206 and / or the drop mode 212 may be set or modified differently (e.g., independently) than the configuration of the slope in the lower voltage drop limit 204 and / or the digging mode 208.

[0055] Figure 3 Figure 300 illustrates the response to a detected change in voltage 306 relative to a reference voltage 308, which can be obtained from... Figure 1Example output currents 302 and 304 are implemented in the welding power supply 100. Output current 302 represents a "harder" arc, where the arc control parameters are set to a harder value. Output current 304 represents a "softer" arc, where the arc control parameters are set to a softer value.

[0056] When the output voltage 306 is substantially equal to the reference voltage 308, the output currents 302 and 304 are substantially equal to the current setpoint 310. At the first example time 312, the output voltage 306 drops below the reference voltage 308. In response to the voltage drop, the control circuit 106 controls the output currents 302 and 304 to increase the output current above the current setpoint 310 by an amount proportional to the drop in voltage 306, wherein the harder output current 302 increases more than the softer output current 304 (e.g., with a higher slope).

[0057] At the second example time 314, the output voltage 306 increases above the reference voltage 308. In response to the voltage drop, the control circuit 106 controls the output currents 302 and 304 to decrease in an amount proportional to the increase in voltage 306, causing the output current to drop below the current setpoint 310, wherein the harder output current 302 decreases more than the softer output current 304 (e.g., at a higher slope).

[0058] At the third example time 316, the output voltage 306 drops below the reference voltage 308 again. In response to the voltage drop, the control circuit 106 again controls the output currents 302 and 304 to increase the output current above the current setpoint 310 by an amount proportional to the drop in voltage 306, in a manner similar to the increase at time 312.

[0059] Figure 4 Figure 400 shows the diagram by... Figure 1 The welding power supply 100 responds to the detection that the output voltage 404 has dropped below the lower voltage threshold (e.g., Figure 2 The example output current is 402, implemented with a lower voltage limit of 202.

[0060] At a first time 406, for example due to a short circuit between the welding rod held by the welding torch 114 and the workpiece 116, the output voltage 404 drops below the lower voltage limit 202. In response to (e.g., by voltage sensing circuit 104) detecting the drop in output voltage 404, control circuit 106 controls the output current 402 to increase it based on an exponential (e.g., parabolic) relationship with respect to time. Equation 1 below illustrates an example exponential relationship: (Formula 1)

[0061] In Equation 1, i is the output current, t is the short-circuit time (e.g., the time elapsed since the detected voltage 404 dropped below the lower voltage limit 202), k is the upper current limit (e.g., a digging limit, which can be set automatically or by the user), h is a value based on the arc control parameter, and a is a variable calculated based on the values ​​of k and h (or the arc control parameter and the digging limit) to cause the output current curve to begin at the output current before the short circuit (e.g., current 410) and end at the upper digging current limit (e.g., current limit 412). In some examples, the exponential relationship causes the output current curve to mimic or resemble the output current curve of an engine-driven generator, which is influenced by the magnetic characteristics (e.g., inductance) of the generator components.

[0062] If the output current 402 reaches the current limit 412, the control circuit 106 controls the output current 402 to make it equal to the current limit 412 (e.g., not exceeding the current limit 412). If the control circuit 106 detects that the welding rod is stuck to the workpiece (e.g., the output current 402 remains at the current limit 412 for at least a threshold time), the control circuit 106 can stop the output and alert the operator that the short circuit has not been cleared.

[0063] At the second time 408, the short circuit is cleared and the arc is restarted, causing the output voltage 404 to increase above the lower voltage limit 202. In response to detecting that the increase in voltage 404 is above the lower voltage limit 202, the control circuit 106 controls the output current 402 to decrease to current 410. In some examples, the decrease in current 402 can be based on another exponential relationship, which may be similar to Equation 1, but results in a decrease in output current relative to the current when the short circuit is cleared. In other examples, the decrease in current 402 can be an immediate (e.g., as fast as the power conversion circuit 102) change in output current, and / or a linear current ramp to current 410.

[0064] Figure 5 An example user interface 500 is shown, which can be used to implement Figure 1 The example welding power supply 100 has a user interface 110 for receiving current, arc control, digging range, and / or slope parameters. The example user interface 500 includes input devices 502, 504, 506, 508 for current, arc control, digging range, and / or slope parameters, and output devices 510, 512 for providing a current value indication for each output parameter.

[0065] Example Ampere Input Device 502 enables the welding operator to set ampere parameters (e.g., in...). Figure 2 (The output amperes at the reference voltage of 216).

[0066] Example arc control input device 504 receives input from the welding operator to control Figure 2 The slope of the output current in the voltage drop mode (e.g., when the output voltage is between voltage limits 204 and 206), and the control Figure 4 One or more factors in the exponential relationship (e.g., increasing or decreasing the time required to reach the digging current limit 412 and / or reach the current level 410). The configuration of the current slope in the descent mode and / or the exponential relationship in the digging mode can be considered in terms of a “softer” curve (e.g., smoother) or a “harder” curve (e.g., more penetrating).

[0067] The excavation range input device 506 receives input from the welding operator to set a current upper limit for the short-circuit cleaning current (e.g., setting...). Figure 4 (Current limit 412). In some examples, control of the fall mode and / or current limit 412 is related to... Figure 4 The exponential relationship is separated to provide welding operators with greater control to fine-tune arc characteristics, thereby providing a greater degree of arc control.

[0068] In some examples, the slope input device 508 allows the welding operator to adjust the slope of the inverse voltage-current relationship in a drop mode (e.g., voltage range 212). Example slope ranges may be -1.5 to -3 amperes (A / V) per volt above and / or below a reference voltage 216 (e.g., 27 volts, which may be modified based on the voltage drop across the welding cable).

[0069] One or more input devices 502-508 can be combined into a single input device, utilizing a menu system to access the desired parameter to be modified. In some examples, one of the input devices 504-508 (e.g., digging range input device 506) is configured with a combination of voltage drop and digging parameters, such as simultaneously increasing the digging current limit 412, reducing the time to reach the digging current limit 412, and increasing the descent slope (e.g., towards -3 A / V), or simultaneously decreasing the digging current limit 412, increasing the time to reach the digging current limit 412, and decreasing the slope (e.g., towards -1.5 A / V). Configuring two, three, or four related parameters into a single input (e.g., simultaneously improving arc characteristics relative to conventional control schemes) reduces the control required from the welding operator but provides simplicity for welding operators who are not interested in granular control.

[0070] Alternatively, input devices 502-508 may be combined into fewer input devices, utilizing menus and / or other types of input devices to select one or more parameters configured by a given input device.

[0071] Figure 6A and 6BTogether, a flowchart representing an example machine-readable instruction 600 is shown, which can be derived from... Figure 1 Example welding power supply 100 performs to provide power for welding operations.

[0072] In block 602, control circuitry 106 determines whether one or more arc control inputs have been received. Example arc control inputs may include any one of arc control input device 504, digging range input device 506, and / or slope input device 508, and / or any other input that modifies current parameters. If an arc control input has been received (block 602), in block 604, control circuitry 106 selects arc control parameters based on the arc control input. For example, control circuitry 106 may configure one or more of the following: ampere parameter, positive and / or negative ampere-voltage slope in drop mode, arc control parameter, digging range (e.g., digging current limit 412), increasing and / or decreasing slope in digging mode, and / or any other parameter.

[0073] After selecting the arc control parameters (block 604), or if no arc control input is received (block 602), in block 606, control circuit 106 determines whether a current input has been received. For example, control circuit 106 can monitor the input to current input device 502, thereby specifying the output current. If a current input has been received (block 606), in block 608, control circuit 106 selects the output current based on the current parameter input. Figure 2 Within the output voltage range of 210, the control circuit 106 uses the output current.

[0074] After selecting the output current (block 604), or if no current input is received (block 606), in block 610, control circuit 106 determines whether a welding arc has been established. For example, control circuit 106 may determine whether a current control loop is being executed to control power conversion circuit 102. If an arc has not been established (block 610), control returns to block 602.

[0075] If a welding arc is established (block 610), in block 612, control circuit 106 executes a current control loop to control power conversion circuit 102 to convert main power 112 into welding power. In block 614, voltage sensing circuit 104 and / or voltage compensator 118 measure the welding voltage (e.g., power supply output voltage, arc voltage, etc.).

[0076] Turning Figure 6BIn block 616, control circuitry 106 (e.g., via voltage comparator 108) determines whether the measured welding voltage is less than a lower threshold voltage (e.g., voltage limit 202). If the measured welding voltage is less than the lower voltage limit 202 (block 616), in block 618, control circuitry 106 enters a digging mode to control the output current. See below. Figure 7 Describe an example method for implementing block 618.

[0077] If the measured welding voltage is greater than the lower voltage limit 202 (block 616), in block 620, the control circuit 106 determines whether the measured welding voltage is between the lower voltage limit 204 and the upper voltage limit 206. If the measured welding voltage is between the measured welding voltages, i.e., between the lower voltage limit 204 and the upper voltage limit 206 (block 620), in block 622, the control circuit 106 controls the output current based on the difference between the output voltage and the reference voltage 216.

[0078] After entering and exiting the digging mode (block 618) and / or controlling the output current (block 622), control returns to block 610. If the measured welding voltage is not between the measured welding voltages, but between the lower drop voltage limit 204 and the upper drop voltage limit 206 (e.g., the output voltage is higher than the upper drop voltage limit 206) (block 620), in block 624, control circuit 106 stops the welding output. Control then returns to block 602.

[0079] Figure 7 This is a flowchart representing example machine-readable instruction 700, which consists of... Figure 1 The example welding power supply 100 executes to control the output current in response to a measured welding voltage dropping below a threshold (e.g., to clear a short circuit). For example, in response to a detected short circuit, example instruction 700 can be executed to implement block 618 to perform a digging mode. Reference will be made below. Figure 4 The diagram 400 is used to describe instruction 700.

[0080] In block 702, control circuit 106 determines whether output voltage 404 is greater than a lower threshold (e.g., Figure 2 The lower voltage limit 202). If the output voltage 404 is not greater than the lower voltage limit 202 (block 702), in block 704, the control circuit 106 determines whether the output current is less than the upper limit of the digging current (e.g., the upper limit of the digging current 412). The upper limit of the digging current 412 can be based on the digging range input (e.g., the lower voltage limit 202). Figure 5 The input is 506.

[0081] If the output current is less than the upper limit of the digging current (block 704), in block 706, the control circuit 106 increases the output current 402 based on an exponential relationship. For example, the control circuit 106 can be based on an exponential relationship, such as Equation 1. Then control returns to block 702.

[0082] If the output current is not less than the upper limit of the digging current (block 704), in block 708, the control circuit 106 maintains the output current 402 at the upper limit of the digging current 412. In block 710, the control circuit 106 determines whether a timeout has occurred if the output voltage 404 has not increased to exceed the lower voltage limit 202. If the timeout has not occurred (block 710), control returns to block 702.

[0083] If a timeout has occurred (block 710), in block 712, control circuit 106 detects the stuck solder rod and cuts off the output current. Control can then return to... Figure 6A The box 610.

[0084] If the output voltage 404 is not greater than the lower voltage limit 202 (block 702), in block 714, the control circuit 106 determines whether the output current is greater than a reference current (e.g., current 410). If the output current 402 is greater than the reference current (block 714), in block 716, the control circuit 106 reduces the output current 402. For example, the control circuit 106 may reduce the output current based on a linear ramp, an exponential relationship similar to Equation 1, an immediate reduction, and / or any other relationship.

[0085] The apparatus and / or methods of the present invention can be implemented in hardware, software, or a combination of hardware and software. The methods and / or systems can be implemented in a centralized manner or in a distributed manner in at least one computing system, processor, and / or other logic circuit, wherein different components are distributed across several interconnected computing systems, processors, and / or other logic circuits. Any kind of computing system or other apparatus suitable for performing the methods described herein is applicable. A typical combination of hardware and software may be a processing system integrated into a welding power supply having a program or other code that, when loaded and executed, controls the welding power supply to perform the methods described herein. Another typical embodiment may include application-specific integrated circuits or chips, such as field-programmable gate arrays (FPGAs), programmable logic devices (PLDs), or complex programmable logic devices (CPLDs), and / or system-on-a-chip (SoCs). Some embodiments may include non-transitory machine-readable (e.g., computer-readable) media (e.g., FLASH memory, optical discs, magnetic disks, etc.) storing one or more lines of machine-executable code that enables 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, but excludes propagated signals.

[0086] Control circuit 106 can identify the welding conditions for a given weld and automatically find the optimal current rise rate for those conditions. Example control circuit implementations can be Atmel Mega16 microcontrollers, STM32F407 microcontrollers, field-programmable logic circuits, and / or any other control or logic circuit capable of executing instructions that execute the welding control software. The control circuit can also be implemented using analog circuitry and / or a combination of digital and analog circuitry. The examples described herein are based on an engine-driven adhesive welding machine, but can be used or modified for any type of high-frequency switching power supply.

[0087] While this method and / or system has been described with reference to certain embodiments, it should be understood that those skilled in the art can make various changes and substitutes with equivalents without departing from the scope of this method and / or system. Furthermore, many modifications can be made to adapt specific situations or materials to the teachings of this disclosure without departing from its scope. 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.

Claims

1. A welding power supply, comprising: A power conversion circuit configured to convert supplied power into welding current and output the welding current to at least one of a shielded metal arc welding (SMAW) electrode or a gouging torch; A voltage sensing circuit configured to measure the output voltage of the power conversion circuit; as well as The control circuit is configured as follows: The power conversion circuit is controlled by a current-controlled control loop based on the target current. When the output voltage is higher than the lower voltage limit, it operates in droop mode when the output voltage is between the lower and upper droop voltage limits. as well as In response to detecting that the output voltage has dropped below the lower voltage limit, the welding current output by the power conversion circuit is controlled based on a first exponential relationship. In the descent mode, the control circuit is configured to control the target current based on the difference between the reference voltage and the output voltage by decreasing the target current when the output voltage is higher than the reference voltage and by increasing the target current when the output voltage is lower than the reference voltage.

2. The welding power supply according to claim 1 further includes an engine configured to drive a generator configured to provide the supplied power to the power conversion circuit.

3. The welding power supply according to claim 1 further includes a user interface configured to receive arc control parameters.

4. The welding power supply of claim 1, wherein, The first exponential relationship is not based on the voltage error between the lower voltage limit and the output voltage.

5. The welding power supply according to claim 1, wherein, The control circuit is configured to control the welding current output by the power conversion circuit based on a second exponential relationship and arc control parameters in response to detecting that the output voltage has increased above the lower voltage limit.

6. The welding power supply according to claim 5, wherein, The second exponential relationship is not based on the voltage error between the lower voltage limit and the output voltage.

7. The welding power supply according to claim 5, wherein, At least one of the first exponential relationship or the second exponential relationship includes a parabolic relationship with respect to time.

8. The welding power supply according to claim 1, wherein, The reference voltage is between 25V and 30V.

9. The welding power supply according to claim 8, wherein, The reference voltage is between 26V and 28V.

10. The welding power supply according to claim 1, wherein, The control circuit is configured to limit the welding current output based on the upper limit of the output current when the output voltage is less than the lower voltage limit.

11. The welding power supply according to claim 1, further comprising an input device configured to receive an input, the arc control parameters being based on the input.

12. The welding power supply according to claim 1, wherein, The control circuit is configured to control the welding current output by the power conversion circuit based on a current setpoint in response to detecting that the output voltage has increased above the lower voltage limit.

13. The welding power supply according to claim 1, wherein, The control circuit is configured as follows: When the output voltage is lower than the reference voltage, the target welding current output by the power conversion circuit is controlled to give the target welding current a first ampere-volt ratio; as well as When the output voltage is higher than the reference voltage, the target welding current is made to have a second ampere / volt ratio that is different from the first ampere / volt ratio when the output voltage is lower than the reference voltage.

14. The welding power supply according to claim 1, wherein, The control circuit is configured to, when controlling the power conversion circuit to output the welding current based on the first exponential relationship, in response to detecting that the output voltage has not increased above the lower voltage limit within a threshold time period, control the power conversion circuit to output the welding current at the upper current limit.

15. The welding power supply of claim 14, further comprising an input device configured to receive an input, the upper current limit being based on the input.

16. The welding power supply of claim 1, further comprising a voltage compensator configured to modify at least one of the lower voltage limit or the reference voltage based on a calculated voltage drop in at least one of the welding cable or the working cable.

17. The welding power supply according to claim 1, wherein, The voltage sensing circuit is configured to measure the output voltage near the arc generated by the welding current.

18. The welding power supply according to claim 1, wherein, The lower voltage limit is 19 volts.

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