Detection device and welding power supply

Abstract

To provide a detection device capable of detecting abnormality of a detection section for detecting a physical amount.SOLUTION: A detection device D1 includes a detection sensor 21, a correction section 22 and an abnormality detection section 4. The detection sensor 21 outputs a detection signal according to a physical amount. The correction section 22 corrects a detection signal input from the detection sensor 21 and outputs a detection signal after correcting. The abnormality detection section 4 detects abnormality of the detection sensor 21 or the correction section 22. The correction section 22 includes an offset adjustment part 223 for performing offset adjustment of a detection signal input from the detection sensor 21. The abnormality detection section 4 detects abnormality of the detection sensor 21 or the correction section 22 when there is needed offset adjustment by exceeding an adjustable range by the offset adjustment part 223.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a detection device and a welding power supply. [Background technology]

[0002] Conventionally, welding power supplies perform feedback control to keep the welding current at a set value. Patent Document 1 discloses an example of a welding power supply that performs feedback control. The welding power supply described in Patent Document 1 detects the welding current value with a current detection unit, and performs feedback control by comparing the detected current value with a set current value so that the welding current value becomes the set current value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6417545 Summary of the Invention [Problem to be solved by the invention]

[0004] In conventional welding power supplies, the current detector for detecting the welding current is, for example, a CT (instrument current transformer) or a Hall current detector. The current detector may become abnormal depending on the duration of use, the environment in which the welding power supply is used, and the purpose of use. For example, a resistor built into the current detector may become corroded by sulfide substances and the like, causing a high resistance value. When an abnormality occurs in the current detector, the correct current value is not detected, and a deviation occurs between the actual current value and the detected value. If feedback control is performed in a state where such a deviation occurs, there is a risk that the welding current cannot be controlled to the set current. As a result, problems such as "unstable arc," "no arc," "welding between the welding electrode (e.g., welding wire or welding rod) and the workpiece," or "no high-frequency power is output in TIG welding" occur. The inability to detect the correct value due to the above-mentioned abnormality is not limited to the current detector used in the welding power supply, but occurs in detectors that detect various physical quantities as well.

[0005] The present disclosure has been made in view of the above circumstances, and has an object to provide a detection device and a welding power supply device that are capable of detecting an abnormality in a detection unit that detects a physical quantity. [Means for solving the problem]

[0006] A detection device provided by a first aspect of the present disclosure includes a detection sensor that outputs a detection signal corresponding to a physical quantity, a correction unit that corrects the detection signal and outputs the corrected detection signal, and an abnormality detection unit that detects an abnormality in the detection sensor or the correction unit, wherein the correction unit includes an offset adjustment unit that performs offset adjustment of the detection signal input from the detection sensor, and the abnormality detection unit detects the abnormality when offset adjustment is necessary beyond the range adjustable by the offset adjustment unit.

[0007] In a preferred embodiment of the detection device, the detection sensor is installed on a first line and outputs a detection signal corresponding to a current flowing through the first line, the offset adjustment unit includes a first adjustment circuit that adjusts the detection signal at an output terminal of the correction unit, the first adjustment circuit includes a first potentiometer that adjusts the detection signal at the output terminal to a signal corresponding to 0 A when no current is flowing through the first line, and the abnormality detection unit detects the abnormality when the detection signal at the output terminal in the non-powered state does not become a signal corresponding to 0 A even after adjustment by the first adjustment circuit.

[0008] In a preferred embodiment of the detection device, the correction unit includes an absolute value circuit that receives a detection signal from the detection sensor and outputs a detection signal shaped into an absolute value signal, and the offset adjustment unit further includes a second adjustment circuit that adjusts the detection signal shaped into an absolute value signal at a reference point of a second line electrically interposed between the absolute value circuit and the output terminal of the correction unit, the second adjustment circuit including a second potentiometer that adjusts the voltage of the detection signal at the reference point in the non-powered state to 0 V by adjustment of the second potentiometer, and the abnormality detection unit detects the abnormality when the voltage of the detection signal at the reference point in the non-powered state does not become 0 V even after adjustment by the second adjustment circuit.

[0009] In a preferred embodiment of the detection device, the detection sensor is a Hall element that detects a magnetic field generated by a current flowing through the first line and outputs a voltage signal as the detection signal.

[0010] A welding power supply provided by a second aspect of the present disclosure includes a detection device provided by the first aspect, an inverter circuit that outputs a high-frequency voltage, and a transformer including a primary winding and a secondary winding, the high-frequency voltage being input to the primary winding, and the secondary winding outputs a current to a welding load via the first line.

[0011] In a preferred embodiment of the welding power supply, the welding power supply further includes an input-side detection unit that detects an input current input to the primary winding, and the abnormality detection unit compares a detection value by the input-side detection unit with a detection value by the detection device when a current is flowing through the first line, and detects the abnormality when there is a difference between the results of the comparison that is equal to or greater than a threshold value. Effect of the Invention

[0012] According to the detection device and welding power supply device disclosed herein, the correction unit includes an offset adjustment unit that adjusts the offset of the detection signal input from the detection sensor. If there is no abnormality in the detection unit (detection sensor or correction unit) that detects the physical quantity, the offset of the detection signal can be appropriately adjusted within the adjustable range by the offset adjustment unit, but if there is an abnormality in the detection unit, the offset of the detection signal cannot be appropriately adjusted within the adjustable range by the offset adjustment unit. Therefore, the abnormality detection unit can detect an abnormality in the detection unit (detection sensor or correction unit) when an offset adjustment is required beyond the adjustable range by the offset adjustment unit. [Brief description of the drawings]

[0013] [Figure 1] 1 is a diagram showing a welding power supply including a detection device according to an embodiment; [Diagram 2] 4 is a graph showing an example of adjustment of an output detection signal performed by a second adjustment circuit in the welding power supply shown in FIG. [Diagram 3] 4 is a graph showing an example of adjustment of an output detection signal performed by a first adjustment circuit in the welding power supply shown in FIG. [Figure 4] FIG. 13 is a diagram showing a portion of a welding power supply including a detection device according to a modified example. [Diagram 5] 5 is a graph showing an example of adjustment of an output detection signal performed by a first adjustment circuit in the welding power supply shown in FIG. 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the detection device and welding power supply of the present disclosure will be described below with reference to the drawings.

[0015] Fig. 1 shows a welding power supply A1 equipped with a detection device D1 according to an embodiment. In the example shown in Fig. 1, welding power supply A1 generates an arc between a welding electrode B and a workpiece W and supplies power to the arc. The welding electrode B, the workpiece W, and the generated arc are the load of welding power supply A1, and therefore the combination of these is referred to as the "welding load." It should be noted that welding power supply A1 is not limited to being used in a welding machine that performs arc welding.

[0016] 1, welding power supply A1 includes a rectifying and smoothing circuit DR1, an inverter circuit INV, a transformer INT, a rectifying and smoothing circuit DR2, an input side detection unit 1, an output side detection unit 2, a control unit 3, an abnormality detection unit 4, and a notification unit 5. Of these, output side detection unit 2 and abnormality detection unit 4 form detection device D1.

[0017] The rectifying and smoothing circuit DR1 converts AC power input from a commercial power source P into DC power and outputs it. The rectifying and smoothing circuit DR1 includes a rectifying circuit that rectifies the AC current and a smoothing capacitor that smoothes the output of the rectifying circuit. The configuration of the rectifying and smoothing circuit DR1 is not limited.

[0018] The inverter circuit INV is, for example, a single-phase full-bridge type PWM control inverter having four switching elements. The inverter circuit INV converts the DC power input from the rectifying and smoothing circuit DR1 into high-frequency power and outputs it by switching the switching elements according to an output control drive signal input from the control unit 3. Note that the inverter circuit INV may be any circuit that converts DC power into high-frequency power, and may be, for example, a half-bridge type having two switching elements, or may be an inverter circuit of another configuration.

[0019] The transformer INT transforms the high-frequency voltage output by the inverter circuit INV and outputs it to the rectifying and smoothing circuit DR2. The transformer INT includes a primary winding L1 and a secondary winding L2. The primary winding L1 has input terminals connected to the output terminals of the inverter circuit INV, and receives the high-frequency voltage from the inverter circuit INV. The secondary winding L2 has output terminals connected to the input terminals of the rectifying and smoothing circuit DR2, and outputs the transformed high-frequency voltage. The output voltage of the inverter circuit INV is transformed according to the ratio (turn ratio) between the number of turns N1 of the primary winding L1 and the number of turns N2 of the secondary winding L2, and is output to the rectifying and smoothing circuit DR2.

[0020] The rectifying and smoothing circuit DR2 converts the high frequency power input from the transformer INT into DC power and outputs it. The rectifying and smoothing circuit DR2 includes a rectifier circuit that rectifies the high frequency current and a DC reactor that smoothes the high frequency current. The configuration of the rectifying and smoothing circuit DR2 is not limited. One of the output terminals of the rectifying and smoothing circuit DR2 is connected to the welding electrode B, and the other output terminal is connected to the workpiece W. When the welding power supply A1 is used in a welding machine that performs AC welding, an inverter circuit that performs DC-AC conversion is provided downstream of the rectifying and smoothing circuit DR2.

[0021] Control unit 3 controls inverter circuit INV. Control unit 3 performs feedback control of the output current of welding power supply A1. Control unit 3 generates an output control drive signal for controlling the switching element of inverter circuit INV by PWM control based on the deviation between the detected value of output current (welding current) of welding power supply A1 and the set value of the output current. Control unit 3 outputs the generated output control drive signal to inverter circuit INV. The detected value of the output current is calculated based on a signal input from output side detection unit 2 (a corrected output side detection signal described later).

[0022] Output side detection unit 2 detects the output current (welding current) of welding power supply A1, which is a current on the secondary side of transformer INT. Output side detection unit 2 is configured with a current detector using, for example, a Hall element. As shown in FIG. 1, output side detection unit 2 includes a detection sensor 21 and a correction unit 22.

[0023] The detection sensor 21 is installed on a first line 91 electrically interposed between the secondary winding L2 of the transformer INT and the welding load. In this embodiment, the first line 91 connects the rectifying smoothing circuit DR2 and the workpiece W. Unlike the example shown in FIG. 1, the detection sensor 21 may be installed on a line connecting the rectifying smoothing circuit DR2 and the welding electrode B, or on a line connecting the secondary winding L2 and the rectifying smoothing circuit DR2. The detection sensor 21 outputs a detection signal according to a current (output current) flowing through the first line 91. Hereinafter, the detection signal output by the detection sensor 21 is referred to as an "output side detection signal." In addition, a state in which a current flows through the first line 91 is referred to as an "energized state," and conversely, a state in which a current does not flow through the first line 91 is referred to as an "unenergized state." The detection sensor 21 is, for example, a Hall element, which detects a magnetic field generated by a current flowing through the first line 91 and outputs a voltage signal as an output side detection signal. The detection sensor 21 is not limited to a Hall element, and may be another current sensor such as a CT (instrument current transformer). The detection sensor 21 may generate an offset voltage even when no current flows through the first line 91. The offset voltage is superimposed on the output side detection signal, causing an error in the detection value by the output side detection unit 2.

[0024] The correction unit 22 receives the output detection signal from the detection sensor 21 and corrects the output detection signal. The correction unit 22 outputs the corrected output detection signal to the control unit 3 and the abnormality detection unit 4. The correction unit 22 includes an absolute value circuit 221, an inversion circuit 222, and an offset adjustment unit 223.

[0025] The absolute value circuit 221 receives an output side detection signal from the detection sensor 21. The absolute value circuit 221 converts the negative voltage of the input output side detection signal into a positive voltage, and outputs the shaped output side detection signal to the inversion circuit 222. Unlike the example shown in FIG. 1, the correction unit 22 may further include an amplifier circuit in front of the absolute value circuit 221, which amplifies the output side detection signal input from the detection sensor 21. The inversion circuit 222 receives an output side detection signal (a signal shaped into an absolute value signal) from the absolute value circuit 221. The inversion circuit 222 shapes the input output side detection signal into an inverted signal in which the positive and negative of the output side detection signal are inverted, and outputs the shaped output side detection signal to the offset adjustment unit 223.

[0026] The offset adjustment unit 223 performs offset adjustment of the output side detection signal so that the above error due to the offset voltage generated by the detection sensor 21 is eliminated. The offset adjustment unit 223 has a predetermined adjustable range, and performs offset adjustment within this adjustable range. The offset adjustment unit 223 performs offset adjustment of the output side detection signal in a non-energized state. This offset adjustment in a non-energized state is called "zero adjustment". For example, the offset adjustment unit 223 performs zero adjustment when no welding current is output immediately after power-on of the welding power supply A1. The offset adjustment unit 223 may be added immediately after power-on of the welding power supply A1, and may perform zero adjustment periodically in a non-energized state, or may perform zero adjustment by an operation by the user of the welding power supply A1 (for example, pressing an inspection button). When the zero adjustment is completed, the offset adjustment unit 223 maintains the state after the zero adjustment. As a result, when there is no abnormality in the output side detection unit 2, even if an offset voltage is superimposed on the output side detection signal input from the detection sensor 21, the output side detection signal is corrected to a signal without error due to the offset voltage by the offset adjustment of the offset adjustment unit 223.

[0027] The offset adjustment unit 223 includes a first adjustment circuit 223a and a second adjustment circuit 223b. In this embodiment, the correction unit 22 first performs offset adjustment on the output side detection signal input from the detection sensor 21 by the second adjustment circuit 223b, and then performs offset adjustment by the first adjustment circuit 223a, thereby correcting the output side detection signal.

[0028] The second adjustment circuit 223b adjusts the output side detection signal at the reference point X shown in FIG. 1. As shown in FIG. 1, the reference point X is located on the second line 92 electrically interposed between the absolute value circuit 221 and the output terminal T1 of the correction unit 22. In this embodiment, the second line 92 connects the inversion circuit 222 and the first adjustment circuit 223a. The second adjustment circuit 223b includes a second potentiometer PM2 as shown in FIG. 1. In the above zero adjustment, the second adjustment circuit 223b adjusts the second potentiometer PM2 (changes the resistance value) so that the voltage of the output side detection signal at the reference point X in a non-energized state (hereinafter referred to as the "reference point voltage") becomes 0 (zero) V. At this time, the output of the absolute value circuit 221 (the output side detection signal shaped into an absolute value signal) is adjusted by adjusting the second potentiometer PM2. When the second adjustment circuit 223b adjusts the reference point voltage in the non-energized state to 0V, it maintains the adjustment value (resistance value) of the second potentiometer PM2 at that time. In this disclosure, "0 (zero)" is not limited to strict "0 (zero)" but means a value in a range that is substantially regarded as "0 (zero)" in consideration of the resolution of each part. The adjustment of the second potentiometer PM2 is preferably automatic, but may be manual. In addition, the second potentiometer PM2 may be digital or analog. The second adjustment circuit 223b is capable of adjusting the reference point voltage within a predetermined adjustable range. Therefore, when the reference point voltage is beyond the adjustable range from 0V, the reference point voltage may not be adjusted to 0V even by the above-mentioned zero adjustment. In addition, the adjustable range of the second adjustment circuit 223b corresponds to the variable range of the resistance value of the second potentiometer PM2, and when the variable range of the resistance value of the second potentiometer PM2 is large, the adjustable range also becomes large (and vice versa).

[0029] FIG. 2 is a graph showing an example of adjustment of the output side detection signal performed by the second adjustment circuit 223b. In FIG. 2, the horizontal axis indicates the actual output current flowing through the first line 91, and the vertical axis indicates the reference point voltage. FIG. 2(a) is a graph when there is no abnormality in the output side detection unit 2, and FIG. 2(b) is a graph when there is an abnormality in the output side detection unit 2. In FIGS. 2(a) and 2(b), the dotted line indicates the output side detection signal at the reference point X before correction, and the solid line indicates the output side detection signal at the reference point X after correction. In FIG. 2(a), the reference point voltage becomes 0V when the output current flowing through the first line 91 is 0A due to the adjustment by the second adjustment circuit 223b for both samples Y1 and Z1. On the other hand, in FIG. 2(b), the reference point voltage does not become 0V when the output current flowing through the first line 91 is 0A for both samples Y2 and Z2, even due to the adjustment by the second adjustment circuit 223b. Therefore, as can be seen from Figures 2(a) and (b), when there is no abnormality in the output side detection unit 2, the reference point voltage can be adjusted to 0V, but when there is an abnormality in the output side detection unit 2, the reference point voltage cannot be adjusted to 0V.

[0030] The first adjustment circuit 223a adjusts the output side detection signal at the output terminal T1 of the correction unit 22. Hereinafter, the output side detection signal at the output terminal T1 of the correction unit 22 may be referred to as the "output terminal signal". The first adjustment circuit 223a includes a first potentiometer PM1 as shown in FIG. 1. In the above-mentioned zero adjustment, the first adjustment circuit 223a adjusts (changes the resistance value) the first potentiometer PM1 so that the output terminal signal in the non-energized state becomes a signal corresponding to 0 A. That is, the first adjustment circuit 223a adjusts the output side detection signal so that the detection value of the output current detected by the control unit 3 becomes 0 (zero) A. When the first adjustment circuit 223a adjusts the output terminal signal in the non-energized state to a signal corresponding to 0 A, it maintains the adjustment value (resistance value) of the first potentiometer PM1 at that time. The first potentiometer PM1 may be of a digital type or an analog type. The first adjustment circuit 223a is capable of adjusting the output side detection signal within a predetermined adjustable range. Therefore, when the output side detection signal exceeds the adjustable range from a signal corresponding to 0 A, even the above-mentioned zero adjustment may not be able to adjust the output end signal to a signal corresponding to 0 A. The adjustable range of the first adjustment circuit 223a corresponds to the variable range of the resistance value of the first potentiometer PM1, and when the variable range of the resistance value of the first potentiometer PM1 is large, the adjustable range also becomes large (and vice versa).

[0031] FIG. 3 is a graph showing an example of adjustment of the output side detection signal performed by the first adjustment circuit 223a. In FIG. 3, the horizontal axis indicates the actual output current flowing through the first line 91, and the vertical axis indicates the detection value of the output current detected by the control unit 3 (i.e., the output end signal converted into the output current value). FIG. 3(a) is a graph when there is no abnormality in the output side detection unit 2, and FIG. 3(b) is a graph when there is an abnormality in the output side detection unit 2. In FIGS. 3(a) and 3(b), the dotted line indicates the detection value of the output current corresponding to the output end signal before correction (the output side detection signal at the output end T1), and the solid line indicates the detection value of the output current corresponding to the output end signal after correction. In FIG. 3(a), the detection value of the output current becomes 0 A when the output current flowing through the first line 91 is 0 A due to the adjustment by the first adjustment circuit 223a for both samples Y3 and Z3. 3(b), in both samples Y4 and Z4, even with adjustment by first adjustment circuit 223a, the detected value of the output current is not 0 A when the output current flowing through first line 91 is 0 A. Therefore, as can be seen from FIGs. 3(a) and (b), when there is no abnormality in output side detection unit 2, the detected value of the output current can be adjusted to 0 A (i.e., the output end signal is a signal corresponding to 0 A), but when there is an abnormality in output side detection unit 2, the detected value of the output current cannot be adjusted to 0 A (i.e., the output end signal is a signal corresponding to 0 A).

[0032] In the energized state, the correction unit 22 corrects the output side detection signal input from the detection sensor 21 by offset adjustment by the offset adjustment unit 223, and outputs the corrected output side detection signal to the control unit 3 and the abnormality detection unit 4. The correction unit 22 also outputs the reference point voltage and the output end signal after the zero adjustment by the offset adjustment unit 223 to the abnormality detection unit 4. If there is a change in the reference point voltage during the zero adjustment, the correction unit 22 determines that the adjustment by the second adjustment circuit 223b is in progress, and if there is no change in the reference point voltage or the reference point voltage is 0V, the correction unit 22 determines that the adjustment by the second adjustment circuit 223b is completed. If there is a change in the output end signal during the zero adjustment, the correction unit 22 determines that the adjustment by the first adjustment circuit 223a is in progress, and if there is no change in the output end signal or the output end signal is a signal corresponding to 0A, the correction unit 22 determines that the adjustment by the first adjustment circuit 223a is completed. Unlike the example shown in FIG. 1, the output side detector 2 may include an A / D converter after the corrector 22.

[0033] The input side detection unit 1 detects an input current, which is a current on the primary side of the transformer INT and is input to the primary winding L1. The input side detection unit 1 includes a detection sensor 11 and a correction unit 12, as shown in FIG.

[0034] The detection sensor 11 is installed on a third line 93 that connects the inverter circuit INV and the primary winding L1 of the transformer INT. The detection sensor 11 outputs a detection signal according to a current (input current) flowing through the third line 93. The detection signal output by the detection sensor 11 is referred to as an "input side detection signal." The detection sensor 11 is composed of, for example, a Hall element or a CT.

[0035] The correction unit 12 corrects the input-side detection signal input from the detection sensor 11, and outputs the corrected input-side detection signal to the abnormality detection unit 4. The correction unit 12 is configured similarly to the correction unit 22, and corrects the input-side detection signal by performing offset adjustment of the input-side detection signal.

[0036] The abnormality detection unit 4 detects an abnormality in the output side detection unit 2 (detection sensor 21 or correction unit 22). When the offset adjustment of the output side detection signal is required beyond the adjustable range of the offset adjustment unit 223 during the zero adjustment, the abnormality detection unit 4 detects an abnormality in the detection sensor 21 or correction unit 22. Furthermore, the abnormality detection unit 4 compares the detected value of the input current with the detected value of the output current in a power-on state, and detects an abnormality in the detection sensor 21 or correction unit 22 when the result of the comparison shows a difference equal to or greater than a threshold value. Specifically, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 according to the following three judgment criteria:

[0037] In the first judgment criterion, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when the reference point voltage does not become 0V even by the adjustment by the second adjustment circuit 223b in the non-energized state. That is, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when the reference point voltage needs to be adjusted beyond the adjustable range of the second adjustment circuit 223b during the zero adjustment. Specifically, after the zero adjustment, the abnormality detection unit 4 checks the reference point voltage after the zero adjustment input from the correction unit 22, and if the reference point voltage is not 0V, it judges that the output side detection unit 2 is abnormal. In an example different from this embodiment, when the reference point voltage cannot be adjusted to 0V by the zero adjustment, a signal indicating that fact is output from the correction unit 22 to the abnormality detection unit 4, and the abnormality detection unit 4 may judge that the output side detection unit 2 is abnormal when the signal indicating that the adjustment could not be made is input.

[0038] If there is no abnormality in the output side detection unit 2, the offset voltage of the output side detection signal falls within the standard value, and the reference point voltage can be adjusted to 0 V by the adjustment of the second adjustment circuit 223b in the above-mentioned zero adjustment. However, if there is an abnormality in the output side detection unit 2, the offset voltage of the output side detection signal falls outside the standard value, and the reference point voltage cannot be adjusted to 0 V even by the adjustment of the second adjustment circuit 223b in the above-mentioned zero adjustment. Therefore, if the reference point voltage does not become 0 V even after adjustment by the second adjustment circuit 223b in a power-off state, the abnormality detection unit 4 can detect that an abnormality has occurred in the output side detection unit 2 (detection sensor 21 or correction unit 22).

[0039] In the second judgment criterion, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when the output end signal does not become a signal corresponding to 0 A even after adjustment by the first adjustment circuit 223a in a non-energized state. That is, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when the output end signal needs to be adjusted beyond the adjustable range of the first adjustment circuit 223a in the zero adjustment. Specifically, the abnormality detection unit 4 checks the output end signal input from the correction unit 22 after the zero adjustment, and judges that the output side detection unit 2 is abnormal if the output end signal is not a signal corresponding to 0 A. In an example different from this embodiment, if the output end signal cannot be adjusted to a signal corresponding to 0 A by the zero adjustment, a signal indicating that fact may be output from the correction unit 22 to the abnormality detection unit 4, and the abnormality detection unit 4 may judge that the output side detection unit 2 is abnormal when the signal indicating that the adjustment was not possible is input.

[0040] If there is no abnormality in the output side detection unit 2, the offset voltage of the output side detection signal falls within the standard value, so the output end signal can be adjusted to a signal corresponding to 0 A by the adjustment of the first adjustment circuit 223a in the above-mentioned zero adjustment. However, if there is an abnormality in the output side detection unit 2, the offset voltage of the output side detection signal falls outside the standard value, so the output end signal cannot be adjusted to a signal corresponding to 0 A even by the adjustment of the first adjustment circuit 223a in the above-mentioned zero adjustment. Therefore, if the output end signal does not become a signal corresponding to 0 A even after adjustment by the first adjustment circuit 223a in a power-off state, the abnormality detection unit 4 can detect that an abnormality has occurred in the output side detection unit 2 (detection sensor 21 or correction unit 22).

[0041] In the third judgment criterion, the abnormality detection unit 4 compares a first multiplication value (Iin×N1) of the input current detection value Iin (for example, an average value for 0.1 seconds) and the number of turns N1 of the primary winding L1 with a second multiplication value (Iout×N2) of the output current detection value Iout (for example, an average value for 0.1 seconds) and the number of turns N2 of the secondary winding L2. If the result of the comparison indicates that there is a difference between the first multiplication value and the second multiplication value that is equal to or greater than a threshold value calculated by, for example, (output current detection value Iout×α+β)×the number of turns N2 of the secondary winding L2, the abnormality of the output side detection unit 2 is detected. Note that, for example, a value between 0 and 1 is substituted for α, and, for example, a value between 0 and 200 is substituted for β. For example, the abnormality detection unit 4 calculates the absolute value of the difference between the first multiplication value and the second multiplication value, and if the calculated value is equal to or greater than the threshold value, detects an abnormality of the output side detection unit 2. The detection value of the input current is calculated based on the input side detection signal input from the input side detection unit 1, and the detection value of the output current is calculated based on the output side detection signal input from the output side detection unit 2. Information on the number of turns N1 and the number of turns N2 is preset in the abnormality detection unit 4. The transformer INT performs voltage transformation according to the turn ratio between the primary winding L1 and the secondary winding L2, so if there is no abnormality in the output side detection unit 2, the first multiplied value and the second multiplied value will be approximately the same value (Iin×N1≒Iout×N2). However, if there is an abnormality in the output side detection unit 2, a difference of equal to or greater than the threshold value will occur between the first multiplied value and the second multiplied value. Therefore, the abnormality detection unit 4 can detect that an abnormality has occurred in the output side detection unit 2 (the detection sensor 21 or the correction unit 22) when there is a difference of equal to or greater than the threshold value by comparing the detection value of the input current and the detection value of the output current.

[0042] The abnormality detection unit 4 performs the abnormality detection based on the first judgment criterion and the second judgment criterion when the zero adjustment by the offset adjustment unit 223 is completed. In this embodiment, the abnormality detection based on the first judgment criterion and the second judgment criterion is performed, for example, after the zero adjustment immediately after the power supply of the welding power supply device A1 is turned on. The abnormality detection based on the first judgment criterion and the second judgment criterion may be performed according to the timing when the zero adjustment by the offset adjustment unit 223 is completed, and may be performed after the zero adjustment performed periodically in a non-energized state, or after the zero adjustment performed by the operation of the user of the welding power supply device A1 (for example, pressing the inspection button). The abnormality detection unit 4 performs the abnormality detection based on the third judgment criterion in a power-on state in which the welding current is output (when welding is being performed). The abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when any one of the three judgment criteria is satisfied. Unlike this configuration, the abnormality detection unit 4 may detect an abnormality in the output side detection unit 2 when two or more of the three judgment criteria are satisfied. When the abnormality detection unit 4 detects an abnormality in the output side detection unit 2, it notifies the abnormality in the output side detection unit 2 via the notification unit 5. The notification by the notification unit 5 may be, for example, a display using a display device or a voice output using a speaker.

[0043] According to this embodiment, the welding power supply A1 includes a detection device D1. The detection device D1 includes a detection sensor 21 that outputs an output side detection signal, a correction unit 22 that corrects the output side detection signal, and an abnormality detection unit 4 that detects an abnormality in the detection sensor 21 or the correction unit 22. The correction unit 22 includes an offset adjustment unit 223 that performs an offset adjustment of the output side detection signal, and the offset adjustment unit 223 includes a first adjustment circuit 223a and a second adjustment circuit 223b. The first adjustment circuit 223a adjusts the output side detection signal at the output terminal T1 so that the output side detection signal at the output terminal T1 in the non-energized state (when the output current is 0 A) becomes a signal corresponding to 0 A. The second adjustment circuit 223b adjusts the output side detection signal at the reference point X so that the voltage (reference point voltage) of the output side detection signal at the reference point X in the non-energized state becomes 0 V. However, when an abnormality occurs in the output side detection unit 2 due to corrosion caused by sulfide substances, the offset voltage of the detection sensor 21 may be outside the standard value, compared to when no abnormality occurs. In addition, due to an abnormality in the output side detection unit 2, the correction unit 22 may not be able to properly adjust the first adjustment circuit 223a and the second adjustment circuit 223b. As a result, the adjustment by the first adjustment circuit 223a may not be able to adjust the output side detection signal at the output terminal T1 to a signal corresponding to 0 A, and the adjustment by the second adjustment circuit 223b may not be able to adjust the voltage of the output side detection signal at the reference point X to 0 V. In other words, when an abnormality occurs in the output side detection unit 2, the offset adjustment of the output side detection signal is required beyond the adjustable range by the offset adjustment unit 223. Therefore, the abnormality detection unit 4 can detect that an abnormality has occurred in the detection sensor 21 or the correction unit 22 when the offset adjustment of the output side detection signal is required beyond the adjustable range by the offset adjustment unit 223. In other words, welding power supply A1 (detection device D1) can detect an abnormality (offset abnormality) in output side detection section 2 based on the inability to adjust the offset of the output side detection signal.

[0044] According to this embodiment, welding power supply A1 includes a transformer INT and an input side detector 1 that detects a current (input current) on the primary side of the transformer INT. If there is no abnormality in the output side detector 2, the multiplied value (second multiplied value) of the detected output current and the number of turns N2 of the secondary winding L2 is approximately the same as the multiplied value (first multiplied value) of the detected input current and the number of turns N1 of the primary winding L1, as described above. On the other hand, if a gain abnormality occurs in the output side detector 2, the detected value of the output side detector 2 becomes larger or smaller than the actual current value flowing through the first line 91, and therefore the second multiplied value does not become approximately the same as the first multiplied value. Therefore, abnormality detection unit 4 compares the detection result of input side detection unit 1 (detection value of input current) with the detection result of output side detection unit 2 (detection value of output current), and if the result of the comparison shows a difference equal to or greater than a threshold value, it can detect that an abnormality has occurred in detection sensor 21 or correction unit 22 (note that in this embodiment, the calculated value of (detection value of output current Iout×α+β)×number of turns N2 of secondary winding L2 is used as the threshold value). In other words, welding power supply A1 can detect an abnormality (gain abnormality) in output side detection unit 2 based on the comparison between the detection value of output side detection unit 2 and the detection value of input side detection unit 1.

[0045] According to this embodiment, welding power supply A1 can detect an abnormality in output side detection unit 2 (detection sensor 21 or correction unit 22) by detection device D1 as described above, and can notify the user of welding power supply A1 of the abnormality and urge him / her to replace the part (output side detection unit 2). This enables welding power supply A1 to appropriately perform feedback control of the output current.

[0046] According to this embodiment, in the welding power supply A1, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when the reference point voltage does not become 0V even after adjustment by the second adjustment circuit 223b during the zero adjustment (the first judgment criterion). Furthermore, the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 when the output end signal does not become a signal corresponding to 0A even after adjustment by the first adjustment circuit 223a during the zero adjustment (the second judgment criterion). Even in conventional welding power supplies, the first potentiometer PM1 and the second potentiometer PM2 may be mounted to perform offset adjustment (zero adjustment) of the detection sensor 21 that detects the output current (welding current). In this way, in a welding power supply equipped with the first potentiometer PM1 and the second potentiometer PM2, it is possible to detect an abnormality in the output side detection unit 2 (i.e., to configure the detection device D1) without increasing costs.

[0047] In the above embodiment, the abnormality detection unit 4 compares a first multiplication value of the detected input current and the number of turns N1 of the primary winding L1 with a second multiplication value of the detected output current and the number of turns N2 of the secondary winding L2, and detects an abnormality in the output side detection unit 2 if the result of the comparison shows a difference of, for example, equal to or greater than (output current×α+β)×the number of turns N2 of the secondary winding L2. Alternatively, the abnormality detection unit 4 may compare a detected input current with a detected output current, and detect an abnormality in the output side detection unit 2 if the result of the comparison shows a difference of equal to or greater than a threshold value taking into account the number of turns N1 of the primary winding L1 and the number of turns N2 of the secondary winding L2. Alternatively, the abnormality detection unit 4 may be configured to detect an abnormality in the output side detection unit 2 based on the ratio of the second multiplied value to the first multiplied value if the ratio is outside a predetermined range, or may be configured to detect an abnormality in the output side detection unit 2 based on the ratio of the detected value of the output current to the detected value of the input current if the ratio is outside a predetermined range taking into account the number of turns N1 of the primary winding L1 and the number of turns N2 of the secondary winding L2.

[0048] In the above embodiment, an example has been shown in which the correction unit 22 of the output side detection unit 2 includes the absolute value circuit 221. Unlike this configuration, the correction unit 22 of the output side detection unit 2 may not include the absolute value circuit 221, as shown in Fig. 4. In this case, as shown in Fig. 4, the offset adjustment unit 223 may not include the second adjustment circuit 223b.

[0049] FIG. 5 is a graph showing an example of adjustment of the output side detection signal performed by the first adjustment circuit 223a in the configuration shown in FIG. 4, and corresponds to FIG. 3. In FIG. 5(a), in both samples Y5 and Z5, the detection value of the output current becomes 0 A when the output current flowing through the first line 91 is 0 A due to the adjustment of the first adjustment circuit 223a. On the other hand, in FIG. 5(b), in both samples Y6 and Z6, the detection value of the output current does not become 0 A when the output current flowing through the first line 91 is 0 A even by the adjustment of the first adjustment circuit 223a. Therefore, as can be understood from FIGS. 5(a) and (b), when there is no abnormality in the output side detection unit 2, the detection value of the output current can be adjusted to 0 A (i.e., the output end signal is a signal corresponding to 0 A), but when there is an abnormality in the output side detection unit 2, the detection value of the output current cannot be adjusted to 0 A (i.e., the output end signal is a signal corresponding to 0 A). Therefore, even in the welding power supply having the configuration shown in FIG. 4, an abnormality in the output side detection unit 2 can be detected.

[0050] In the above embodiment, an example has been shown in which the output-side detection unit 2 outputs the corrected output-side detection signal to the control unit 3 and the abnormality detection unit 4. Unlike this configuration, the output-side detection unit 2 may calculate a current value of the output current based on the corrected output-side detection signal and output the current value to the control unit 3 and the abnormality detection unit 4. The same is true for the input-side detection unit 1, in which the input-side detection unit 1 may calculate a current value of the input current based on the corrected input-side detection signal and output the current value to the abnormality detection unit 4.

[0051] In the above embodiment, an example has been described in which the abnormality detection unit 4 detects an abnormality in the output side detection unit 2. Unlike this configuration, the abnormality detection unit 4 may further detect an abnormality in the input side detection unit 1, similar to the abnormality detection in the output side detection unit 2. For example, when the input side detection signal output from the detection sensor 11 is corrected by the correction unit 12, the abnormality detection unit 4 may detect an abnormality in the detection sensor 11 or the correction unit 12 in a case where the input side detection signal needs to be offset adjusted beyond an adjustable range of an offset adjustment unit (configured similarly to the offset adjustment unit 223) provided in the correction unit 12.

[0052] In the above embodiment, an example has been shown in which the abnormality detection unit 4 detects an abnormality in the output side detection unit 2 (Hall current detector) for detecting the welding current, but this is not limited to this, and the abnormality detection unit 4 may also detect abnormalities in other sensors used in the welding machine (for example, a shielding gas flow sensor, a cooling water flow sensor, or a voltage sensor for detecting the welding voltage).

[0053] In the above embodiment, the detection device D1 is applied to the welding power supply A1, but the present invention is not limited to this, and the detection device D1 can be applied to various devices. That is, the detection device D1 may be applied to a device other than the welding power supply A1, and may detect an abnormality in a detection unit that detects a physical quantity in the other device. For example, the detection device D1 may be applied to electric power equipment, electronic equipment, industrial equipment, and the like.

[0054] The detection device and welding power supply according to the present disclosure are not limited to the above-described embodiment, and the specific configurations of the components of the detection device and welding power supply according to the present disclosure can be freely designed in various ways. [Explanation of symbols]

[0055] A1: welding power supply, D1: detection device, 1: input side detection section, 11: detection sensor, 12: correction section, 2: output side detection section, 21: detection sensor, 22: correction section, 221: absolute value circuit, 222: inversion circuit, 223: offset adjustment section, 223a: first adjustment circuit, 223b: second adjustment circuit, 3: control section, 4: abnormality detection section, 5: notification section, 91: first line, 92: second line, DR1: rectification smoothing circuit, DR2: rectification smoothing circuit, INT: transformer, INV: inverter circuit, L1: primary winding, L2: secondary winding, PM1: first potentiometer, PM2: second potentiometer, T1: output terminal, X: reference point, B: welding electrode, W: workpiece

Claims

1. A detection sensor that outputs a detection signal corresponding to a physical quantity; a correction unit that corrects the detection signal and outputs the corrected detection signal; an abnormality detection unit that detects an abnormality in the detection sensor or the correction unit; Equipped with the correction unit includes an offset adjustment unit that performs offset adjustment of a detection signal input from the detection sensor, The detection sensor is installed on a first line and outputs a detection signal corresponding to a current flowing through the first line; the offset adjustment unit includes a first adjustment circuit that adjusts the detection signal at an output terminal of the correction unit; the first adjustment circuit includes a first potentiometer, and adjusts the detection signal at the output terminal to a signal corresponding to 0 A when no current is flowing through the first line by adjusting the first potentiometer; The abnormality detection unit detects the abnormality by determining that an offset adjustment is necessary beyond the adjustable range by the offset adjustment unit when the detection signal at the output terminal in the power-off state does not become a signal corresponding to 0 A even after adjustment by the first adjustment circuit.

2. the correction unit includes an absolute value circuit that receives a detection signal from the detection sensor and outputs the detection signal shaped into an absolute value signal; the offset adjustment unit further includes a second adjustment circuit that adjusts the detection signal shaped into the absolute value signal at a reference point of a second line electrically interposed between the absolute value circuit and an output terminal of the correction unit, the second adjustment circuit includes a second potentiometer, and adjusts a voltage of the detection signal at the reference point to 0 V in the non-energized state by adjusting the second potentiometer; The detection device according to claim 1 , wherein the abnormality detection unit detects the abnormality when a voltage of the detection signal at the reference point in the non-energized state does not become 0 V even after adjustment by the second adjustment circuit.

3. 3. The detection device according to claim 1, wherein the detection sensor is a Hall element that detects a magnetic field generated by a current flowing through the first line and outputs a voltage signal as the detection signal.

4. A detection device according to any one of claims 1 to 3, an inverter circuit that outputs a high frequency voltage; a transformer including a primary winding and a secondary winding, the high-frequency voltage being input to the primary winding; The secondary winding outputs a current to a welding load via the first line.

5. An input side detection unit that detects an input current input to the primary winding, 5. The welding power supply device according to claim 4, wherein the abnormality detection unit compares a detection value by the input side detection unit with a detection value by the detection device when a current is flowing through the first line, and detects the abnormality when a difference between the results of the comparison is equal to or greater than a threshold value.

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