System and method for inductance compensation in a welding-type system

Systems and methods for inductance compensation in a welding-type system include a reel configured to wind a welding-type cable to reduce a first portion of the welding-type cable extending from the reel, and to unwind to increase the first portion of the welding-type cable extending from the reel, wherein a second portion of the welding-type cable is at least partially wound around the reel when stored. A controller determines a first length of the first portion of the welding-type cable, calculates a first inductance of the first portion of welding-type cable extending from the reel based on the first length, determines a second length of the second portion of the welding-type cable, calculates a second inductance of the second portion of welding-type cable wound around the reel based on the second length, and calculates a cable inductance of the welding-type cable based on the first inductance and the second inductance.

BACKGROUND

Welding systems often employ welding-type cables to supply power and/or carry information to and from welding-type tools (e.g., a welding torch, a plasma cutter, etc.) and/or accessories (e.g., a wire feeder, an induction heater, etc.). Industries that require on-site welding (e.g., the pipeline and construction industries) employ welding power sources with welding-type cables connecting a welding-type tool. For instance, a length of welding-type cable is connected on one end to the welding power source (e.g., a welding-type power supply), with a second end connected to the welding-type tool. The tool is then brought to the work area.

Often, the unwound cable is exposed to the environment (e.g., a work site, a shipyard, an industrial setting, etc.), which can cause damage to the cable. The cable may also be folded or coiled in a manner which causes kinks, which may lead to damage to the cable, especially in a multi-function welding-type cable. Storage of long welding-type cables may be implemented by rolling, winding, folding, or other means of transporting and attaching the cable to a portable reel (e.g., wrapping the work cable around the power supply, the shielding gas cylinder, etc.).

In certain work environments a welding location or workpiece can be located a long distance from a welding power source. When current flows through a welding cable an inductance created therein can adversely affect the operation of the welding system and the quality of the weld obtained. Thus, a system to calculate and mitigate such secondary inductance is desirable.

SUMMARY

Apparatus and methods are disclosed for inductance compensation in a welding-type system. In particular, disclosed example welding-type systems are configured to determine an inductance value of a welding-type cable based on a length measurement of the cable and to adjust a parameter of the welding-type system in response to the determined inductance, in accordance with aspects of this disclosure.

DETAILED DESCRIPTION

In examples disclosed herein, a welding-type system is configured to determine an inductance value of a welding-type cable and adjust a parameter of the welding-type system in response to the determined inductance. For example, properties that affect the inductance of the weld power cable may include the total length of the cable, the materials that make up conductors within the weld power cable (e.g., power conductors, data carriers, gas and/or wire guides, etc.), disposition of the weld power cable (e.g., coiled, straight), disposition relative to conductive materials (e.g., coiled around a metal rod, gas canister, etc.), arrangement relative to other power cables (e.g., parallel to, twisted about, etc.), and proximity to inductive sources (e.g., other power cables).

In some examples, the cable can be wound around an object (e.g., a reel) such that a first length of the cable is parallel to a second length of the cable (see, e.g., the wound portion). As a current is applied to the cable, a magnetic field is generated in each of the parallel cables. The magnetic field from the first length will influence the inductance in the second length, increasing the inductance. The increased inductance requires an increased power output from the power supply to achieve the same level of power output at the welding tool.

Example welding-type systems disclosed herein are configured to determine and mitigate an inductance in the welding-type cable. In particular, the welding-type system includes a reel configured to wind a welding-type cable during storage and unwind the cable for use. The system determines if a portion of the welding-type cable is at least partially wound around the reel when stored. In some examples, a controller is configured to determine a length of the portion of the welding-type cable extending from the reel, such as by one or more sensors to measure a length of the extended portion (e.g., an optical scanner, a mechanical length measuring device, etc.) and based on predetermined parameters (e.g., a predetermined value of the total cable length, a power input value, etc.).

Based at least in part on the determined length of the extended portion, the controller calculates an inductance value of the extended portion of welding-type cable reel. For example, the controller can be configured to consider a number of parameters, such as the type of cable in use, welding process, amount of power/voltage/current being output, system and/or environmental temperature, to name only a few. Based on the calculated and known parameters, the controller is configured to calculate the inductance of the extended portion of the welding-type cable.

Based at least in part on the determined length of the extended portion, the controller determines a length of the portion of the welding-type cable wound around the reel (e.g., by subtracting the length of the extended portion from the value of the total cable length, by identification of a marking along a length of the cable, etc.). The controller then calculates an inductance of the portion of welding-type cable wound around the reel based on the length, and known and calculated parameters.

Based at least in part on the calculated inductance of the wound and unwound portions of the welding-type cables, the controller is then configured to calculate an inductance of the total welding-type cable based on the first inductance and the second inductance.

In some examples, the controller includes a memory device that includes a plurality of values that associates a length of the portion of the cable wound around the reel with corresponding inductance values. The values can be calculated based on known or estimated values corresponding to a diameter of the reel, a width of the reel, a diameter of the cable, a power/voltage/current output through the cable, the welding process, etc. Based at least in part on these values, the number of coils about the reel can be calculated or estimated. An inductance of the portion of the cable about the reel, based on the number of turns, the input, etc., can then be determined. The values can be stored as a matrix or look-up table, for instance.

The controller is further configured to access the memory device to determine the inductance of the wound portion by looking up the length of the second portion of the welding-type cable as provided by the values.

Having determined the inductance value associated with the cable, the controller is further configured to control a welding parameter or welding system parameter of the welding-type system based on the calculated cable inductance. For example, as the inductance value increases, in order to maintain a desired output at the welding-type torch, the power/voltage/current input (e.g. from the power supply) may be required to increase. A welding system parameter may also be measured, compared and adjusted. As such, operation of a control loop, such as the rate of the loop, can be adjusted based on monitored system parameters. Thus, if the inductance value exceeds a threshold amount, the controller may control an output or operation of the system to mitigate the effects of the increased inductance.

As used herein, the term “welding-type 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 term “welding-type power supply” refers to any device capable of, when power is applied thereto, supplying welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding) power, including but not limited to inverters, converters, resonant power supplies, quasi-resonant power supplies, and the like, as well as control circuitry and other ancillary circuitry associated therewith.

As used herein, a “circuit” (e.g., controller, control circuit, etc.) includes any analog and/or digital components, power and/or control elements, such as a microprocessor, digital signal processor (DSP), software, and the like, discrete and/or integrated components, or portions and/or combinations thereof.

FIG.1is an example welding-type power supply100which incorporates a retractable cable reel102. The reel102is configured to wind and unwind a cable104. A portion of the cable106can extend from the reel102and through an opening118(the portion outside of the power supply100represented as cable106′) of the power supply100, and connect with a welding-type tool114(e.g., a welding-type torch, a plasma cutter, induction heating device, work clamp, etc.). Another portion108of the cable104is wound around the reel102and stored until needed.

In examples, the reel102is connected to a power input of the power supply100via an electrical connector, which can include a slip-ring, a brush contact, or other conductive member that allows current to flow during rotation of the reel102.

The wound portion108is repeatedly extended and retracted through the opening118during and after each use. In some examples, the reel102can be mounted within the housing of the welding-type power supply100, and be configured to rotate as the cable104is wound and unwound. For example, the cable104can be partially stored on the reel102and pass through the opening118. The cable104can be withdrawn from the housing by pulling on the cable104, by turning a crank, by a motorized method, or other suitable means.

As the unwound portion106,106′ of the cable104is extended/retracted, a sensor112can be located along the cabling path, such as at the opening118. The sensor112can be configured to measure the length of the cable104, such as measuring the amount of cable that is unwound (portion106,106′). The sensor112can be, for example, a tachometer, a digital or an analog rotary encoder, a mechanical length measuring meter, an optical scanner, or other suitable sensor. For example, the digital or analog rotary encoder can be configured to count a number of revolutions of the reel based on a length of the cable104passing the sensor112during winding and unwinding of the welding-type cable.

In some examples, the mechanical length measuring meter can be configured to measure the length of the extended cable portion106,106′ during winding and unwinding of the welding-type cable. The measurement can be used to calculate the amount of cable108remaining on the reel102, in view of known and/or calculated and/or estimated parameters such as total length of the cable104, circumference of the reel102, the diameter of the cable104, for instance.

Additionally or alternatively, the sensor112can be configured to recognize a pattern or series of marks along the length of the cable104, as shown inFIG.2. For example, a number of marks122can be located along the length that indicates a unit of measure (e.g., a marking at every meter, foot, etc.). In some examples, the cable104may have the length marked at different intervals, similar to a common ruler. In other examples, the markings can be a recognized pattern, such as a bar code124, QR code126, or other scannable information that allows the sensor112to determine the length of cable104unwound from the reel102. Additionally or alternatively, the markings can indicate information about the cable104. The information can include a total length and/or weight of the cable104, a unit length and/or weight of the cable104, an inductance value per length of a straight portion of the cable104, or other information useful in determining the inductance of the cable104.

Returning toFIG.1, the controller110can receive a signal from the sensor112indicating a length of wire106,106′ unwound from the reel102. Based on a total length of the cable104, the controller110calculates the length of the unwound portion106,106′, which can be used to determine an inductance of the wound portion108. This inductance value can be used to adjust an output of the power supply100(e.g., a voltage, a current, etc.) to mitigate the effects of inductance on the welding-type operation.

Operation of the power supply100can be governed by use of one or more interfaces120. The interface120can provide commands, display and communication with one or more devices. In some examples, the interface120can adjust and/or monitor operational settings by a modified and/or configurable user interface. In an example, a button can be used to select a welding operation, which can then be adjusted (e.g., with a dial, a touch panel, a membrane switch, etc.). The interface120can provide alerts and or information, such as an indication as to the selected welding-type operation, a power output value, and calculated inductance, or other useful information.

As illustrated inFIG.1, the interface120may be on a control panel integrated with the power supply100. The interface120can include one or more switches and/or buttons, each having a singular and/or multi-purpose function. In some examples, the interface120can operate a motor powering the reel102. For instance, a user can initiate an automatic rewinding of the cable104onto the reel102by activating the motor. A motor control can be configured to adjust the speed and/or torque applied to the reel102as the cable104is retracted. In an example, the interface120can communicate with a remote interface.

Cord management systems, such as the reel102, can be integrated with the power supply100allowing the cable104to be neatly wound around the reel102in an enclosed housing when the cable104is not in use. In some examples, the reel102is mounted on a frame113directly inside a welding-type power supply100. An additional sensor can be included with the frame113, configured to measure a weight of the reel102and the wound portion108of the cable104(see, e.g., weight sensor144ofFIG.3). Based on the known and/or calculated and/or estimated weight of the reel102, a weight of the wound portion108can be determined. Based on the determined weight, an amount of cable108about the reel102can be calculated. Thus, the number of turns about a reel102of a particular diameter can be determined, which can be used to determine an inductance value of the wound portion. For example, a list of values can be stored in the memory that associated weight measurements of the wound portion108a length of the wound portion108can be calculated.

In an example, the reel102can include a spring to provide the force needed to rotate the reel102and thereby retract the cable104back into the power supply100. The addition of multiple or stronger springs can increase the tension for certain applications that use large or heavy cables. In some examples, the spring can be made of spiral spring made of a resilient material, such as steel. An extension connector can be attached to an end of the cable108to prevent the entirety of the cable108from retracting into the housing, as well as provide for connectivity to a variety of welding-type tools114(e.g., a work clamp). In some examples, the reel102is spring driven, which will allow for the reel102to automatically rewind. The reel102features a locking ratchet that allows for a certain amount of the cable104to be pulled from the system without the cable104being pulled back onto the reel102. The cable reel102provides a current path through a conductor (e.g., a slip ring) that allows the current to travel from the welding-type power supply to a welding-type tool (e.g., a welding torch).

In an example, the reel102features a locking ratchet that allows for a certain amount of the cable104to be pulled from the system without the cable104being pulled back onto the reel. The locking ratchet further allows retraction of the cable108into the housing upon release of the locking ratchet. In some examples, a motor can cause the reel102to wind and/or unwind, allowing the cable portion106,106′ to extend from the power supply100. In an example, the reel102is mechanically connected to a manual device which can be used to wind and unwind the cable104. The manual device can be a crank or other type of turn, which may not automatically rewind the cable104. In a situation where an override function is needed, the manual device can allow for extraction and/or retraction of the cable104when, for example, no power is available for a motorized retractor.

Thus, the disclosed reel102can include a retractable cord system that is durable and can withstand high operational use, such as repeated winding and unwinding of the welding-type cable104. The reel104can be compact, integrated with other welding-type systems (e.g., a welding-type power supply) which reduces clutter and the need for multiple devices. As such, the cable104should be constructed to withstand the amount of force needed to withdraw the cable104from the welding-type power supply100without damaging or breaking the cable104.

In some examples, the construction of the connector can be customized to provide for power, gas, wire, and/or other welding-type inputs and consumables (e.g., for FCAW welding, a cable with an integrated gas line, etc.). In other examples, the retractable cable management system can be used for a variety of cables/tubing/cords, etc. For example, a cable that includes tubing may need to be wound in a large loop to avoid damage to the wire, such as kinks, during winding and unwinding. In some examples, the retractable system can be used to wind and unwind a gas line, a ground cable, or other types of welding-type cables.

In some examples, the power supply100can include both a welding-type cable for a torch as well as a power return cable connected to a work clamp (not shown), with each configured to be stored on separate reels within the power supply100. Additionally or alternatively, each cable can be further connected to another reel (not shown) to extend the reach and capability of the retractable cable system. Moreover, an integrated and/or external reel may provide power and/or control signals to accessories to the power supply100(e.g., a wire feeder, a heating unit, etc.).

Although illustrated in a welding-type power supply, the controller and reel system described herein can be integrated into a variety of portable welding-type systems, such as in a welding-type cart, a rack system, a wire feeder, or other suitable housing. In some examples, a stand-alone “smart” reel can be mounted remotely from a welding-type power supply. A reel can be mounted to a vehicle or other surface or object on or near a job site. The reel can include sensors and components as described with respect to reel104, and communicate with the welding-type power supply by a wired or wireless connection. Via the connection, information and/or power can be exchanged between the reel and the welding-type power supply to determine an inductance value for the cable, as described herein.

FIG.3shows a block diagram of an example implementation of the controller110ofFIG.1. The controller110includes a communication interface130to transmit information to and receive information from one or more devices. The interface130is operatively connected to the user interface120, a welding control138, a calculation engine146, a weight sensor144, and the sensor112(e.g., a length measurement sensor). The controller110further includes a memory132which contains a matrix or other listing of inductance values134, a matrix or other listing of weight values135, as well as a matrix or other list of welding parameter values or welding system parameter values136.

As described herein, the controller110communicates with the user interface120, the calculation engine146, the weight sensor144, and the sensor112to determine an inductance of the cable104, and controls the power supply100via the welding control138accordingly. The example controller110ofFIG.3may be a general-purpose computer, a laptop computer, a tablet computer, a mobile device, a server, and/or any other type of computing device integrated or remote to the power supply. In some examples, the controller110is implemented in a cloud computing environment, on one or more physical machines, and/or on one or more virtual machines.

The controller110may receive input from the user interface120through which the power supply100receives commands from, for example, an operator (e.g., a welder). In some examples, the operator may employ the user interface120to choose a welding process (e.g., stick, TIG, MIG, etc.) and desired operating values of the power supply100(e.g., output power, voltage, current, etc.). The user interface120can be configured for inputting commands and/or customizing controls (e.g., graphical user interfaces (GUI), touch screens, communication pathways, etc.). The controller110may be configured to receive and process a plurality of inputs regarding the performance and demands of the power supply100. As described herein, information received from the interface120and other inputs can be used to determine an inductance value of the cable104.

The memory device132may include volatile or non-volatile memory, such as ROM, RAM, magnetic storage memory, optical storage memory, or a combination thereof, and may be integrated with the controller110, located remotely, or a combination of the two. In addition, a variety of control parameters may be stored in the memory device132along with code configured to provide a specific output during operation.

For example, the controller110is configured to access the memory132storing the lists of values134,135,136. In some examples, the controller110and the memory132are integrally located (e.g., within a computing device). In some examples, the controller110is connected to a network interface to access the lists of values134,135,136via a communications network.

The controller110is configured to receive one or more measurements to determine an inductance of the weld cable104. For example, the sensor112measures a length of the cable106,106′ extending from the power supply100. The sensor112can include an optical sensor138, a digital sensor140, and/or a mechanical sensor142, each of which can measure and/or determine a length of the cable106,106′ as it extends through the opening118. In some examples, the optical sensor138and/or the digital sensor140can identify a bar code124, QR code126, or other marker122to determine the length of the cable106,106′, as well as other information. The mechanical sensor142can be a rotary or other type of sensor that measures cable length by physical contact or connection to gears coupled to the reel102. In any case, the length measurement information is sent to the controller110via the communication interface130for processing.

The length measurements are provided to a calculation engine146to determine the length of the cable108wound around the reel102. The controller110compares the length values against a list of inductance values134stored in the memory132. Based on the comparison, the controller110can determine an inductance of both the extending portion of the cable106,106′ and the wound portion of the cable108. The calculation engine146can thus calculate the total inductance of the cable104.

In another example, the controller110receives a weight measurement from the weight sensor144included in the frame113. The controller110compares the weight values against a list of weight values135stored in the memory device132that corresponds weight values to inductance values.

Having determined the inductance of the cable104, the controller110can then compare the inductance value against a matrix or other list of welding parameters or welding system parameter values136. For example, the controller110may utilize a look up table, an algorithm, and/or a model stored in the memory device132to determine the cable inductance based on a relationship between the variables and the values stored in memory132. The controller110can compare the determined welding parameter or welding system parameter against a welding parameter or welding system parameter of the power supply100, and determine if an adjustment is needed. For example, if the determined welding parameter deviates from a welding parameter of the power supply100by a predetermined amount, the welding parameter of the power supply100can be adjusted to mitigate the effects of the inductance and ensure proper operation of the power supply100. The controller110can then adjust a welding parameter in accordance with the determined inductance value to control the power supply100.

In some examples, for known cable inductances, certain welding parameters can be estimated, such as output and input, voltage and current levels, or a range of levels. Based on these estimated welding parameters, any adjustment of a welding operation can be determined empirically. In some examples, the controller110is configured to interpolate an inductance value for the cable104, the corresponding welding parameter values selected based on the value of the inductance value. The welding parameter can then be adjusted to mitigate the effects of the inductance as described herein.

FIGS.4A and4Brepresent a flowchart illustrating example machine readable instructions152which may be executed by the controller110ofFIG.3to determine the inductance of a welding-type cable104and adjusting a welding type parameter of a welding type system100, in accordance with the examples provided inFIGS.1-3. In examples, the instructions152can be stored in the memory132. In the example ofFIG.4A, at block152a first length of the first portion106of the welding-type cable104extending from the reel102is determined. At block154, a first inductance of the first portion106of welding-type cable based on the first length is calculated. At block156, a second length of the second portion108of the welding-type cable is determined based on the first length. At block158, a memory device132that includes a plurality of values134that associates a length of a cable108wound around a reel102with corresponding inductance values is accessed. At block160, the second inductance by looking up the determined second length of the second portion in the memory device is determined. At block162, a cable inductance of the welding-type cable104based on the first inductance and the second inductance is calculated.

Continuing withFIG.4B, at block164the memory device134that includes the plurality of values associating inductance with corresponding welding parameters or welding system parameter values136is accessed. At block166, a welding parameter or welding system parameter is determined by looking up the calculated inductance in the memory device132. At block168, a value of the determined welding parameter or welding system parameter is identified based on the calculated inductance. At block170, the controller110determines whether the identified value falls within a tolerance of a desired value of the welding parameter or welding system parameter. At block172, a value of the welding parameter or welding system parameter of the welding-type system100is adjusted if the comparison determines the identified welding parameter or welding system parameter is outside of the tolerance. If the identified welding parameter or welding system parameter is within the tolerance, the method returns to block168and continues to identify the welding parameters or welding system parameters.

FIG.5is a flowchart representative of example machine readable instructions200which may be executed by the controller110ofFIG.3to determine the inductance of a welding-type cable104and adjusting a welding type parameter of a welding type system100, in accordance with the examples provided inFIGS.1-3. At block202, a weight of a first portion108of welding-type cable wound around a reel102is determined. At block204, a first length of the first portion108of the welding-type cable based on the determined weight is calculated. At block206, a first inductance of the first portion108of welding-type cable wound around the reel based on the first length of welding-type cable is calculated. At block208, a second length of a second portion106of the welding-type cable extending from the reel102based on the determined weight is calculated. At block210, a second inductance of the second portion106of welding-type cable extending from the reel102based on the second length of welding-type cable104is calculated. At block212, a cable inductance based on the first and second inductances is calculated.

The present methods and systems may be realized in hardware, software, and/or a combination of hardware and software. Example implementations include an application specific integrated circuit and/or a programmable control circuit.