Control device and power supply device including the same

Abstract

A control device (90) is provided with: a voltage supply capacitor (938) of a voltage supply circuit (93), which is connected between a collector terminal (771a) and an emitter terminal (771b) of a current adjustment switching element (771), and which is capable of discharging toward the collector terminal (771a); a drive circuit (94) that controls the voltage of the gate terminal (771c); a voltage determination circuit (92) that determines whether or not the voltage between the collector terminal (771a) and the emitter terminal (771b) is equal to or greater than a predetermined threshold value (VTH); and a connection determination unit (95) that causes the drive circuit (94) to turn on the current adjustment switching element (771) from a state in which the voltage between the collector terminal (771a) and the emitter terminal (771b) is equal to or greater than a predetermined threshold value (VTH) and the drive circuit (94) has turned off the current adjustment switching element (771), and that determines the connection state on the basis of the determination result of the voltage determination circuit (92) after a predetermined time has elapsed.

Description

Technical Field

[0001] The present disclosure relates to a control device connected to a switching element and a power supply device including the control device. Background Art

[0002] The following technique is disclosed in Patent Document 1: A wire material is provided so as to cover a wire connecting a first electrical device and a second electrical device, and based on a change in voltage applied to a wire included in the wire material, it is detected whether the wire is broken.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-183120 Summary of the Invention

[0006] -Technical Problem to be Solved by One Invention-

[0007] However, in a system including a switching element and a control device for controlling the switching element, if a wire material is used to cover a wire connecting the switching element and the control device in order to determine the connection state of the wire, it takes time and effort to assemble the wire material to the wire, thereby increasing the manufacturing cost of the system.

[0008] The present disclosure has been completed to solve the above technical problems, and an object thereof is to suppress the manufacturing cost and be able to determine the connection state between the switching element and the control device.

[0009] -Technical Solution for Solving the Technical Problem-

[0010] To achieve the above object, the present disclosure is a control device connected to a switching element having a first terminal, a second terminal, and a third terminal, wherein the third terminal controls the flow of current between the first terminal and the second terminal. The control device is characterized in that it includes a capacitor, a drive circuit, a voltage determination circuit, and a connection determination unit. The capacitor is connected between the first terminal and the second terminal and can discharge toward the first terminal. The drive circuit is connected to the second terminal and the third terminal, and the drive circuit turns the switching element on and off. The voltage determination circuit determines whether the voltage between the first terminal and the second terminal is equal to or higher than a specified threshold. The connection determination unit performs conduction control and determines the connection state between the switching element and the control device based on the determination result of the voltage determination circuit after a specified time has elapsed since the conduction control. In the conduction control, the connection determination unit controls the drive circuit to turn on the switching element from a state in which the voltage between the first terminal and the second terminal is equal to or higher than the specified threshold and the drive circuit has turned off the switching element.

[0011] Thus, by simply providing a capacitor, a drive circuit, and a voltage determination circuit in the control device and having the connection determination unit perform a specified process, it is possible to determine the connection state between the switching element and the control device. Therefore, since it is not necessary to perform special processing such as covering wires with wire on the connection components between the switching element and the control device, manufacturing costs can be reduced.

[0012] -Advantages of the Invention-

[0013] According to the present disclosure, both manufacturing costs are suppressed and the connection state between the switching element and the control device can be determined. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 is a schematic diagram showing the structure of an arc welding apparatus including a power supply device according to a first embodiment of the present disclosure;

[0015] Figure 2 is a circuit diagram of a direct / alternating current conversion circuit;

[0016] Figure 3 is a circuit diagram of a voltage determination circuit;

[0017] Figure 4 is a circuit diagram of a voltage supply circuit;

[0018] Figure 5 is a circuit diagram of a drive circuit;

[0019] Figure 6 is a flowchart for explaining the operation of the connection determination unit;

[0020] Figure 7 is a timing chart showing the levels of respective signals in the case where there is no poor connection;

[0021] Figure 8 is equivalent to the case where the switching element and the current-limiting resistor are not properly connected; Figure 7 of the figure;

[0022] Figure 9 is equivalent to the case where the switching element and the control device are not properly connected; Figure 7 of the figure;

[0023] Figure 10 is a circuit diagram showing the structure of the AC-DC conversion circuit and the control device in the second embodiment. DETAILED DESCRIPTION

[0024] Hereinafter, embodiments of the present disclosure will be described based on the drawings. The following description of the preferred embodiments is merely an example in nature and is not intended to limit the present invention, the application object of the present invention, or the use of the present invention at all.

[0025] (First Embodiment)

[0026] Figure 1 An arc welding apparatus 1 according to a first embodiment of the present disclosure is shown. The arc welding apparatus 1 performs short-circuit arc welding. In this short-circuit arc welding, the arc welding apparatus 1 feeds the welding wire 3 held on the torch 2 toward the base material 5 at a constant feed rate while repeatedly short-circuiting and arcing states. The short-circuit state is a state in which the welding wire 3 is short-circuited with the base material 5, and the arcing state is a state in which an arc is generated between the welding wire 3 and the base material 5. The torch 2 is held by an operator.

[0027] The arc welding apparatus 1 includes a power supply device 7 that supplies a welding current between the welding wire 3 and the base material 5. The power supply device 7 includes a first rectifying circuit 71, an AC-DC conversion circuit 72, a smoothing capacitor 73, an insulating transformer 74, a second rectifying circuit 75, a reactor 76, a switching circuit 77, a first output terminal 80a and a second output terminal 80b, first wires 81a to third wires 81c, a printed circuit board 82, a wire-side connector 83a and a board-side connector 83b as a connector 83, a control device 90, and a display 84.

[0028] The first rectifying circuit 71 converts the power supply voltage output from the AC power supply PS into a DC voltage and outputs the DC voltage from a pair of output nodes ON1, ON2. The first rectifying circuit 71 is constituted by, for example, a diode bridge circuit.

[0029] The AC-DC conversion circuit 72 is a full-bridge AC-DC conversion circuit that generates a first AC voltage based on the voltages of the output nodes ON1 and ON2 of the first rectification circuit 71. Specifically, as Figure 2 shown, the AC-DC conversion circuit 72 includes: a first upper-arm switching element 72a and a first lower-arm switching element 72b connected in series with each other between a pair of output nodes ON1 and ON2 of the first rectification circuit 71; and a second upper-arm switching element 72c and a second lower-arm switching element 72d connected in series with each other between the pair of output nodes ON1 and ON2 of the first rectification circuit 71. Freewheeling diodes 72e are connected in parallel with the respective switching elements 72a to 72d of the AC-DC conversion circuit 72. The AC-DC conversion circuit 72 generates a first AC voltage using the power output from the AC power supply PS through the switching operations of these switching elements 72a to 72d. It should be noted that in this first embodiment, a circuit having four switching elements 72a to 72d is used as the AC-DC conversion circuit 72, but any circuit having at least one switching element can be used, and a circuit having a number of switching elements other than four can also be used as the AC-DC conversion circuit 72.

[0030] The smoothing capacitor 73 is connected in parallel with the first rectification circuit 71 and the AC-DC conversion circuit 72 between the first rectification circuit 71 and the AC-DC conversion circuit 72. The smoothing capacitor 73 is connected between a pair of output nodes 0N1 and 0N2 of the first rectification circuit 71.

[0031] The isolation transformer 74 converts the first AC voltage generated by the AC-DC conversion circuit 72 into a second AC voltage and outputs the second AC voltage. The isolation transformer 74 has a primary coil 74a and a secondary coil 74b. The voltage of the primary coil 74a becomes the first AC voltage, and the voltage of the secondary coil 74b becomes the second AC voltage. The primary coil 74a is connected between the connection point of the first upper-arm switching element 72a and the first lower-arm switching element 72b and the connection point of the second upper-arm switching element 72c and the second lower-arm switching element 72d in the AC-DC conversion circuit 72 (refer to Figure 2 ).

[0032] The second rectification circuit 75 rectifies the output of the isolation transformer 74. Specifically, the second rectification circuit 75 includes a first rectifying diode 75a and a second rectifying diode 75b. The anode of the first rectifying diode 75a is connected to one end of the secondary coil 74b, and the anode of the second rectifying diode 75b is connected to the other end of the secondary coil 74b. The cathodes of the first rectifying diode 75a and the second rectifying diode 75b are connected to a common node.

[0033] One end of the reactor 76 is connected to the above-mentioned common node.

[0034] The switching circuit 77 includes a switching element 771 for current adjustment, a freewheeling diode 772, and a current-limiting resistor 773.

[0035] The switching element 771 for current adjustment is an insulated gate bipolar transistor (IGBT: Insulated Gate Bipolar Transistor). The switching element 771 for current adjustment has a collector terminal 771a as the first terminal, an emitter terminal 771b as the second terminal, and a gate terminal 771c as the third terminal. The gate terminal 771c as the third terminal controls the flow of current between the collector terminal 771a and the emitter terminal 771b. The switching element 771 for current adjustment adjusts the output of the second rectifier circuit 75 by conduction and cutoff, thereby outputting a welding current.

[0036] The freewheeling diode 772 is connected in parallel with the switching element 771 for current adjustment.

[0037] The current-limiting resistor 773 is connected in parallel with the switching element 771 for current adjustment between the collector terminal 771a and the emitter terminal 771b. The resistance value of the current-limiting resistor 773 is set to about 0.25 Ω to 1 Ω.

[0038] The first output terminal 80a is connected to the emitter terminal 771b of the switching element 771 for current adjustment and the welding wire 3.

[0039] The second output terminal 80b is connected to the center tap of the secondary coil 74b and the base material 5.

[0040] One end of the first wire 81a is connected to the collector terminal 771a of the switching element 771 for current adjustment.

[0041] One end of the second wire 81b is connected to the emitter terminal 771b of the switching element 771 for current adjustment.

[0042] One end of the third wire 81c is connected to the gate terminal 771c of the switching element 771 for current adjustment.

[0043] Wire-side connectors 83a are provided at the other ends of the first wire 81a to the third wire 81c.

[0044] A board-side connector 83b and a control device 90 are provided on the printed circuit board 82.

[0045] The wire-side connectors 83a are mounted on the board-side connector 83b.

[0046] The control device 90 includes a circuit section 91 composed of a hardware circuit and a connection determination section 95 composed of a microcomputer.

[0047] The circuit unit 91 includes a voltage determination circuit 92, a voltage supply circuit 93, and a drive circuit 94.

[0048] The voltage determination circuit 92 has a first input terminal 92a and a second input terminal 92b. The first input terminal 92a is connected to the collector terminal 771a of the current adjustment switch element 771 via the first wire 81a and two connectors 83a, 83b. The second input terminal 92b is connected to the emitter terminal 771b of the current adjustment switch element 771 via the second wire 81b and two connectors 83a, 83b. The voltage determination circuit 92 receives the voltages of the collector terminal 771a and the emitter terminal 771b from the first input terminal 92a and the second input terminal 92b respectively via the first wire 81a, the second wire 81b, and two connectors 83a, 83b. And the voltage determination circuit 92 determines whether the voltage between the first input terminal 92a and the second input terminal 92b, that is, the voltage between the collector terminal 771a and the emitter terminal 771b, is a specified threshold V TH (Refer to Figure 8 ) above.

[0049] Specifically, as Figure 3 shown, the voltage determination circuit 92 further includes a first resistor 921 to a sixth resistor 926, an operational amplifier 927, and a first optocoupler 928. The first optocoupler 928 has a light emitting diode 928a and a photosensitive transistor 928b that receives the light of the light emitting diode 928a. It should be noted that, if necessary, in order to suppress the excessive rise of the voltage input to the operational amplifier 927, a protection circuit such as a zener diode can also be connected in parallel with the second resistor 922.

[0050] One end of the first resistor 921 is connected to the first input terminal 92a. The other end of the first resistor 921 is connected to the non-inverting input terminal of the operational amplifier 927. The resistance value of the first resistor 921 is set to be about 100 kΩ.

[0051] One end of the second resistor 922 is connected to the second input terminal 92b, and one end of the second resistor 922 is grounded. The other end of the second resistor 922 is connected to the non-inverting input terminal (positive (+) terminal) of the operational amplifier 927. The resistance value of the second resistor 922 is set to be about 100 kΩ.

[0052] The voltage between the first input terminal 92a and the second input terminal 92b is divided by the first resistor 921 and the second resistor 922, thereby obtaining a voltage Vce that the operational amplifier 927 can process.

[0053] One end of the third resistor 923 is connected to the first power supply Vcc1. The other end of the third resistor 923 is connected to the inverting input terminal (negative (-) terminal) of the operational amplifier 927. The voltage of the first power supply Vcc1 is set to 15V. The resistance value of the third resistor 923 is set to 20kΩ.

[0054] One end of the fourth resistor 924 is grounded. The other end of the fourth resistor 924 is connected to the inverting input terminal of the operational amplifier 927. The resistance value of the fourth resistor 924 is set to 10kΩ.

[0055] The voltage of the first power supply Vcc1 is divided by the third resistor 923 and the fourth resistor 924, thereby obtaining an appropriate voltage Vth for comparison. When the voltage Vce is equal to or higher than the voltage Vth, the operational amplifier 927 outputs a high-level signal. When the voltage Vce is less than the voltage Vth, the operational amplifier 927 outputs a low-level signal. The voltage Vth is set to 5V.

[0056] One end of the fifth resistor 925 is connected to the output terminal of the operational amplifier 927. The other end of the fifth resistor 925 is connected to the anode of the light-emitting diode 928a of the first optocoupler 928.

[0057] One end of the sixth resistor 926 is connected to the second power supply Vcc2. The other end of the sixth resistor 926 is connected to the collector of the photosensitive transistor 928b of the first optocoupler 928. The voltage of the second power supply Vcc2 is set to 5V.

[0058] The cathode of the light-emitting diode 928a of the first optocoupler 928 is connected to the first ground. The emitter of the photosensitive transistor 928b of the first optocoupler 928 is connected to the second ground. When the output of the operational amplifier 927 is high level, the first optocoupler 928 conducts. When the output of the operational amplifier 927 is low level, the first optocoupler 928 cuts off.

[0059] The voltage determination circuit 92 outputs the voltage of the collector of the photosensitive transistor 928b of the first optocoupler 928 as the determination signal S1. When the voltage between the first input terminal 92a and the second input terminal 92b increases and the voltage Vce is equal to or higher than the specified threshold V TH In the above case, the determination signal S1 becomes low level. When the voltage between the first input terminal 92a and the second input terminal 92b is small and the voltage Vce is less than the specified threshold V TH In the case of, the determination signal S1 becomes high level. Therefore, when the voltage determination circuit 92 is normally connected to the current adjustment switch element 771, when the voltage between the collector terminal 771a and the emitter terminal 771b is equal to the specified threshold V THIn the above case, the determination signal S1 becomes low level, and the voltage between the collector terminal 771a and the emitter terminal 771b is less than the specified threshold V TH In the case of, the determination signal S1 becomes high level. That is, when the voltage determination circuit 92 is normally connected to the current adjustment switch element 771, the voltage determination circuit 92 determines whether the voltage between the collector terminal 771a and the emitter terminal 771b is the specified threshold V TH or more.

[0060] The voltage supply circuit 93 has a first control input terminal 93a, a first supply terminal 93b, and a second supply terminal 93c. A voltage supply signal S2 from the connection determination unit 95 is input to the first control input terminal 93a. The first supply terminal 93b is connected to the collector terminal 771a of the current adjustment switch element 771 via the first wire 81a and two connectors 83a, 83b. The second supply terminal 93c is connected to the emitter terminal 771b of the current adjustment switch element 771 via the second wire 81b and two connectors 83a, 83b. The voltage supply circuit 93 supplies a specified voltage from the first supply terminal 93b and the second supply terminal 93c to between the collector terminal 771a and the emitter terminal 771b via the first wire 81a and the second wire 81b, and two connectors 83a, 83b.

[0061] As Figure 4 shown, the voltage supply circuit 93 has a seventh resistor 931 to a tenth resistor 934, a first transistor 935, a second optocoupler 936 and a third optocoupler 937, a voltage supply capacitor 938, and a first diode 939. The second optocoupler 936 has a light emitting diode 936a and a photosensitive transistor 936b that receives the light of the corresponding light emitting diode 936a. The third optocoupler 937 has a light emitting diode 937a and a photosensitive transistor 937b that receives the light of the corresponding light emitting diode 937a.

[0062] One end of the seventh resistor 931 is connected to the second power supply Vcc2. The other end of the seventh resistor 931 is connected to the anodes of the light emitting diode 936a of the second optocoupler 936 and the light emitting diode 937a of the third optocoupler 937.

[0063] The cathode of the light emitting diode 936a of the second optocoupler 936 is connected to the first control input terminal 93a and the base of the first transistor 935.

[0064] The collector of the photosensitive transistor 936b of the second optocoupler 936 is connected to the first power supply Vcc1, and the emitter of the photosensitive transistor 936b of the second optocoupler 936 is connected to one end of the eighth resistor 932.

[0065] The cathode of the light-emitting diode 937a of the third optocoupler 937 is connected to the collector of the first transistor 935.

[0066] The collector of the photosensitive transistor 937b of the third optocoupler 937 is connected to one end of the ninth resistor 933, and the emitter of the photosensitive transistor 937b of the third optocoupler 937 is connected to the first supply terminal 93b via the first diode 939. That is, the cathode of the first diode 939 is connected to the first supply terminal 93b.

[0067] As long as the power supply of the control device 90 is connected, the second optocoupler 936 and the third optocoupler 937 will not be cut off or conducted simultaneously. That is, when one of the second optocoupler 936 and the third optocoupler 937 is conducted, the other is cut off.

[0068] The first diode 939 prevents current from flowing from the switch circuit 77 into the voltage supply circuit 93.

[0069] The emitter of the first transistor 935 is connected to the second ground.

[0070] The other end of the eighth resistor 932 and the other end of the ninth resistor 933 are connected to each other, and the other end of the eighth resistor 932 and the other end of the ninth resistor 933 are connected to one end of the voltage supply capacitor 938 and one end of the tenth resistor 934. The resistance values of the eighth resistor 932 and the ninth resistor 933 are respectively set to about 10 kΩ.

[0071] The other end of the voltage supply capacitor 938 and the other end of the tenth resistor 934 are connected to the second supply terminal 93c. When the power supply of the control device 90 is not connected, the voltage supply capacitor 938 discharges toward the tenth resistor 934 to reduce the voltage, thereby becoming a safe state.

[0072] The capacitance value of the voltage supply capacitor 938 is set to about 10 μF.

[0073] The resistance value of the tenth resistor 934 is set to about 1 MΩ.

[0074] In the voltage supply circuit 93 configured as described above, when the voltage supply signal S2 is at a high level, the first transistor 935 is turned on, the second optocoupler 936 is turned off, and the third optocoupler 937 is turned on. As a result, through the discharge of the voltage supply capacitor 938, current flows from the voltage supply capacitor 938 via the ninth resistor 933 and the first diode 939 to the first supply terminal 93b. On the other hand, when the voltage supply signal S2 is at a low level, the first transistor 935 is turned off, the second optocoupler 936 is turned on, and the third optocoupler 937 is turned off. As a result, current flows from the first power supply Vcc1 via the eighth resistor 932 to the voltage supply capacitor 938, and the voltage supply capacitor 938 is charged. Therefore, when the voltage supply circuit 93 is normally connected to the current adjustment switching element 771 and the voltage supply signal S2 is at a high level, the voltage supply capacitor 938 of the voltage supply circuit 93 can discharge from the first supply terminal 93b toward the collector terminal 771a via the first wire 81a and the two connectors 83a, 83b.

[0075] The drive circuit 94 has a second control input terminal 94a, a first drive terminal 94b, and a second drive terminal 94c. The conduction cutoff signal S3 from the connection determination unit 95 is input to the second control input terminal 94a. The first drive terminal 94b is connected to the emitter terminal 771b of the current adjustment switching element 771 via the second wire 81b and the two connectors 83a, 83b. The second drive terminal 94c is connected to the gate terminal 771c of the current adjustment switching element 771 via the third wire 81c and the two connectors 83a, 83b. The drive circuit 94 supplies a predetermined voltage from the first drive terminal 94b and the second drive terminal 94c to between the emitter terminal 771b and the gate terminal 771c via the second wire 81b and the third wire 81c, and the two connectors 83a, 83b.

[0076] As Figure 5 shown, the drive circuit 94 has an eleventh resistor 941 to a fourteenth resistor 944, a fourth optocoupler 945, a second transistor 946, and a third transistor 947. The fourth optocoupler 945 has a light emitting diode 945a and a photosensitive transistor 945b that receives the light of the light emitting diode 945a.

[0077] One end of the eleventh resistor 941 is connected to the second control input terminal 94a. The other end of the eleventh resistor 941 is connected to the anode of the light emitting diode 945a of the fourth optocoupler 945.

[0078] The cathode of the light emitting diode 945a of the fourth optocoupler 945 is connected to the second ground.

[0079] The emitter of the photosensitive transistor 945b of the fourth optocoupler 945 is connected to the first ground.

[0080] One end of the twelfth resistor 942 is connected to the first power supply Vcc 1. The other end of the twelfth resistor 942 is connected to the collector of the photosensitive transistor 945b of the fourth optocoupler 945.

[0081] The collector of the second transistor 946 is connected to the first power supply Vcc 1.

[0082] The emitter of the third transistor 947 is connected to the emitter of the second transistor 946. The collector of the third transistor 947 is connected to the first ground. The second transistor 946 and the third transistor 947 form a push-pull circuit.

[0083] One end of the thirteenth resistor 943 is connected to the emitters of the second transistor 946 and the third transistor 947. The other end of the thirteenth resistor 943 is connected to the second drive terminal 94c. The resistance value of the thirteenth resistor 943 is set to be about 10 Ω.

[0084] One end of the fourteenth resistor 944 is connected to the second drive terminal 94c. The other end of the fourteenth resistor 944 is connected to the first drive terminal 94b. The resistance value of the fourteenth resistor 944 is set to be about 1 kΩ. By providing the fourteenth resistor 944, the voltage between the first drive terminal 94b and the second drive terminal 94c can be stabilized.

[0085] In the drive circuit 94 configured as described above, when the conduction cutoff signal S3 is at a low level, the fourth optocoupler 945 is cutoff, and the output of the fourth optocoupler 945 (the voltage of the collector of the photosensitive transistor 945b) becomes high level. Also, the output of the push-pull circuit formed by the second transistor 946 and the third transistor 947 (the voltage at one end of the thirteenth resistor 943) becomes high level. Thereby, a high-level voltage is applied between the first drive terminal 94b and the second drive terminal 94c. On the other hand, when the conduction cutoff signal S3 is at a high level, the fourth optocoupler 945 is conductive, and the output of the fourth optocoupler 945 (the voltage of the collector of the photosensitive transistor 945b) becomes low level. Also, the output of the push-pull circuit formed by the second transistor 946 and the third transistor 947 (the voltage at one end of the thirteenth resistor 943) becomes low level. Therefore, the voltage between the first drive terminal 94b and the second drive terminal 94c also becomes low level.

[0086] Therefore, when the connection between the drive circuit 94 and the current adjustment switch element 771 is normal, if a low-level on / off signal S3 is input from the connection determination unit 95 to the drive circuit 94, the drive circuit 94 applies a voltage between the emitter terminal 771b and the gate terminal 771c of the current adjustment switch element 771 via the second wire 81b, the third wire 81c, and the two connectors 83a and 83b, thereby turning on the current adjustment switch element 771. On the other hand, if a high-level on / off signal S3 is input from the connection determination unit 95 to the drive circuit 94, the drive circuit 94 makes the voltage between the emitter terminal 771b and the gate terminal 771c of the current adjustment switch element 771 at a low level via the second wire 81b, the third wire 81c, and the two connectors 83a and 83b, thereby turning off the current adjustment switch element 771.

[0087] The connection determination unit 95 includes a control unit 951, a storage unit 952, a determination unit 953, and a display instruction unit 954. Here, with reference to Figure 6 the flowchart, the operations of the respective units of the connection determination unit 95 will be described.

[0088] First, in the initial state, the control unit 951 charges the voltage supply capacitor 938 of the voltage supply circuit 93 by setting the voltage supply signal S2 to a low level, and turns off the current adjustment switch element 771 (off control state) by setting the on / off signal S3 to a high level.

[0089] Then, in step S101, the control unit 951 discharges the voltage supply capacitor 938 from this initial state by setting the voltage supply signal S2 to a high level. On the other hand, the control unit 951 maintains the on / off signal S3 at a high level, thereby controlling the drive circuit 94 to keep the current adjustment switch element 771 in the off state (off control state).

[0090] Then, in step S102, the control unit 951 stands by for a predetermined time (about 100 ms).

[0091] Next, in step S103, the control unit 951 stores the determination signal S1 at this time as the first determination signal S1a in the storage unit 952.

[0092] Next, in step S104, the control unit 951 sets the on / off signal S3 to a low level. That is, the control unit 951 turns on the current adjustment switch element 771 by setting the on / off signal S3 to a low level. On the other hand, the control unit 951 maintains the voltage supply signal S2 at a high level to keep the voltage supply capacitor 938 in the discharged state.

[0093] Then, in step S105, the control unit 951 stands by for a specified time (about 100 ms).

[0094] Next, in step S106, the control unit 951 stores the determination signal S1 at this time as the second determination signal S1b in the storage unit 952.

[0095] Next, in step S107, the control unit 951 returns the state to the initial state by setting the voltage supply signal S2 to a low level and setting the conduction cutoff signal S3 to a high level.

[0096] Next, in step S108, the determination unit 953 determines the connection state based on the first determination signal S1a and the second determination signal S1b stored in the storage unit 952. The control unit 951 sends the determination result of the determination unit 953 to the display instruction unit 954. The display instruction unit 954 causes the display 84 to display a display indicating the connection state accordingly. Specifically, for example, the display instruction unit 954 displays one of the following three main ideas: no connection defect; a connection defect (disconnection) exists between the current adjustment switch element 771 and the current limiting resistor 773; a connection defect (disconnection) exists between the current adjustment switch element 771 and the control device 90.

[0097] In addition, when the control unit 951 determines that there is a connection defect, it controls the AC-DC conversion circuit 72 and the like to stop welding.

[0098] As shown in Table 1 below, when the first determination signal S1a and the second determination signal S1b are at a high level, the determination unit 953 determines that there is no connection defect. On the other hand, when the first determination signal S1a is at a low level and the second determination signal S1b is at a high level, it is determined that there is a connection defect between the collector terminal 771a and the emitter terminal 771b of the current adjustment switch element 771 and the current limiting resistor 773. In addition, when the first determination signal S1a and the second determination signal S1b are at a low level, it is determined that there is a connection defect between the collector terminal 771a, the emitter terminal 771b, and the gate terminal 771c of the current adjustment switch element 771 and the control device 90.

[0099] [Table 1]

[0100]

[0101] Here,[ Figure 7 shows the levels of the respective signals in the case where there is no connection defect,[ Figure 8 shows the levels of the respective signals in the case where the current adjustment switch element 771 and the current limiting resistor 773 are not properly connected,[ Figure 9Shows the levels of various signals when the switching element 771 for current adjustment is not properly connected to the control device 90.

[0102] In Figures 7 to 9 , T1 represents the execution time of the above-mentioned step S101 (setting the voltage supply signal S2 to high level), T2 represents the execution time of the above-mentioned step S103 (storing the first determination signal S1a), T3 represents the execution time of the above-mentioned step S104 (setting the conduction cutoff signal S3 to low level), T4 represents the execution time of the above-mentioned step S106 (storing the second determination signal S1b), and T5 represents the execution time of the above-mentioned step S107 (setting the voltage supply signal S2 to low level, setting the conduction cutoff signal S3 to high level, and restoring the state to the initial state).

[0103] As Figure 7 shown, in the absence of a connection defect, if the voltage supply signal S2 is set from the initial state to high level at time T1, most of the current from the voltage supply capacitor 938 of the voltage supply circuit 93 flows successively through the ninth resistor 933, the phototransistor 937b of the third optocoupler 937, the first diode 939, and the current limiting resistor 773. In the voltage determination circuit 92, a current path including the first resistor 921 and the second resistor 922 is formed between the first input terminal 92a and the second input terminal 92b, but the resistance value of this current path is set to be ten times or more the resistance value of the current limiting resistor 773. The first resistor 921 and the second resistor 922 constitute a resistance component with a resistance value larger than that of the current limiting resistor 773. Therefore, in the absence of a connection defect, although the first resistor 921 and the second resistor 922 are connected between the collector terminal 771a and the emitter terminal 771b, most of the current from the voltage supply capacitor 938 flows through the current limiting resistor 773. The voltage of the voltage supply capacitor 938 is divided by the ninth resistor 933 and the current limiting resistor 773, but since the resistance value of the current limiting resistor 773 (about 0.25 Ω to 1 Ω) is sufficiently small compared to the resistance value of the ninth resistor 933 (10 kΩ), the voltage of the current limiting resistor 773, that is, the voltage between the collector terminal 771a and the emitter terminal 771b, becomes extremely low and does not reach the specified threshold V THAbove. The resistance value of the ninth resistor 933 is preferably set to be more than a thousand times the resistance value of the current-limiting resistor 773. In addition, the time constant of the circuit through which most of the current from the voltage supply capacitor 938 flows is approximately obtained by the product of the capacitance value (10 μF) of the voltage supply capacitor 938 and the resistance value (10 kΩ) of the ninth resistor 933, and is about 100 ms. Therefore, at time T2 (the cut-off control state in which the current adjustment switching element 771 is cut off (the conduction cut-off signal S3 is set to high level)), the voltage supply capacitor 938 is in a state where a considerable part of the discharge has been performed. After that, if the current adjustment switching element 771 conducts at time T3 (the conduction cut-off signal S3 is set to low level), current also flows to the current adjustment switching element 771, and thus the discharge of the voltage supply capacitor 938 continues. Therefore, at time T3 and time T4, the voltage between the collector terminal 771a and the emitter terminal 771b does not reach the specified threshold value V TH Above.

[0104] In this way, in the absence of a connection failure, the voltage between the collector terminal 771a and the emitter terminal 771b is always less than the specified threshold value V TH , and thus the determination signal S1 is always high level. Therefore, the connection determination unit 95 can determine, based on the determination signal S1 (determination result) at time T2 and time T4, that there is no connection failure between the current adjustment switching element 771 and the current-limiting resistor 773, and between the current adjustment switching element 771 and the control device 90.

[0105] As Figure 8As shown, when the current adjustment switch element 771 and the current limiting resistor 773 are not properly connected, if the voltage supply signal S2 is set to a high level at time T1 from the initial state (the voltage supply signal S2 is set to a low level and the on-off signal S3 is set to a high level), most of the current from the voltage supply capacitor 938 in the voltage supply circuit 93 flows through the ninth resistor 933, the photosensitive transistor 937b of the third optocoupler 937, the first diode 939, and the first resistor 921 and the second resistor 922 in the voltage determination circuit 92 in sequence. The voltage of the voltage supply capacitor 938 is divided by the ninth resistor 933 in the voltage supply circuit 93, the first resistor 921 and the second resistor 922 in the voltage determination circuit 92. The combined resistance value of the first resistor 921 and the second resistor 922 (about 200 kΩ) is large enough compared to the resistance value of the ninth resistor 933 (10 kΩ), specifically, more than ten times the resistance value of the ninth resistor 933. Therefore, most of the voltage of the voltage supply capacitor 938 is applied between the collector terminal 771a and the emitter terminal 771b. Therefore, during the period from time T1 to time T3, the voltage between the collector terminal 771a and the emitter terminal 771b gradually decreases due to the discharge of the voltage supply capacitor 938, but still reaches a specified threshold V TH above state. At time T3, the control unit 951 controls the drive circuit 94 to turn on the current adjustment switch element 771 (perform on control) by setting the on-off signal S3 to a low level. As a result, the current adjustment switch element 771 is turned on, most of the current from the voltage supply capacitor 938 flows to the current adjustment switch element 771, the discharge of the voltage supply capacitor 938 proceeds rapidly, and the voltage between the collector terminal 771a and the emitter terminal 771b is lower than the specified threshold V TH . Therefore, at time T4, 100 ms after time T3 (after a specified time from the switch-on operation), the voltage between the collector terminal 771a and the emitter terminal 771b is less than the specified threshold V TH .

[0106] In this way, when the current adjustment switch element 771 and the current limiting resistor 773 are not properly connected, at time T2 (the off control state where the current adjustment switch element 771 is off), the voltage between the collector terminal 771a and the emitter terminal 771b reaches the specified threshold V TH above, and the determination signal S1 becomes a low level. In addition, at time T4, the voltage between the collector terminal 771a and the emitter terminal 771b is less than the specified threshold V TH, the determination signal S1 becomes high level. Therefore, the connection determination unit 95 can determine, based on these determination signals S1 (determination results), that there is a connection failure between the current adjustment switch element 771 and the current limiting resistor 773, and the current adjustment switch element 771 and the control device 90 are in a normal connection state.

[0107] As Figure 9 shown, when the current adjustment switch element 771 and the control device 90 are not normally connected, similar to the case where there is a connection failure between the current adjustment switch element 771 and the current limiting resistor 773, from time T1 to just before time T3, each signal changes. In addition, even at time T3, the control unit 951 controls the drive circuit 94 to turn on the current adjustment switch element 771 (perform turn-on control) by setting the on-off signal S3 to low level. However, since the current adjustment switch element 771 and the control device 90 are not normally connected, the current adjustment switch element 771 does not turn on. Therefore, after time T3, most of the current from the voltage supply capacitor 938 in the voltage supply circuit 93 continues to flow through the ninth resistor 933, the phototransistor 937b of the third optocoupler 937, the first diode 939, and the first resistor 921 and the second resistor 922 in the voltage determination circuit 92 in sequence. As a result, the discharge of the voltage supply capacitor 938 continues, but compared with the case where the current from the voltage supply capacitor 938 also flows through the normally connected current adjustment switch element 771, the resistance value of the current path becomes larger and the discharge speed becomes slower. Therefore, during the period from time T3 to just before time T5, the voltage between the collector terminal 771a and the emitter terminal 771b becomes the specified threshold V TH in the above state.

[0108] In this way, when the current adjustment switch element 771 and the control device 90 are not normally connected, at time T2 and time T4 (after a specified time from the turn-on control), the voltage between the collector terminal 771a and the emitter terminal 771b becomes the specified threshold V TH or more, and the determination signal S1 becomes low level. Therefore, the connection determination unit 95 can determine, based on these determination signals S1 (determination results), that the current adjustment switch element 771 and the control device 90 are in a state of connection failure.

[0109] Thus, the combination of the determination signal S1 at time T2, i.e., the first determination signal S1a, and the determination signal S1 at time T4, i.e., the second determination signal S1b, varies according to the connection state. Therefore, the determination unit 953 of the control unit 951 performs the determination shown in Table 1 above based on the first determination signal S1a and the second determination signal S1b, thereby enabling the correct determination of the connection state. As a result, it is possible to prevent the deterioration of welding quality or damage to other components caused by welding in a state where the wires 81a to 81c are broken.

[0110] Thus, the control device 90 of the first embodiment is a control device 90 connected to the current adjustment switching element 771. The current adjustment switching element 771 has a first terminal (collector terminal) 771a, a second terminal (emitter terminal) 771b, and a third terminal (gate terminal) 771c. The third terminal (gate terminal) 771c controls the flow of current between the first terminal (collector terminal) 771a and the second terminal (emitter terminal) 771b. The control device 90 of the first embodiment is characterized in that the control device 90 includes a capacitor (voltage supply capacitor) 938, a drive circuit 94, a voltage determination circuit 92, and a connection determination unit 95.

[0111] The capacitor (voltage supply capacitor) 938 is connected between the first terminal (collector terminal) 771a and the second terminal (emitter terminal) 771b and can discharge toward the first terminal (collector terminal) 771a.

[0112] The drive circuit 94 is connected to the second terminal (emitter terminal) 771b and the third terminal (gate terminal) 771c, and the drive circuit 94 turns on and off the current adjustment switching element 771.

[0113] The voltage determination circuit 92 determines whether the voltage between the first terminal (collector terminal) 771a and the second terminal (emitter terminal) 771b is a specified threshold value V. TH Above,

[0114] The connection determination unit 95 performs conduction control and determines the connection state between the current adjustment switching element 771 and the control device 90 based on the determination result of the voltage determination circuit 92 after a specified time has elapsed since the conduction control. In the conduction control, the connection determination unit 95 controls the drive circuit 94 to turn on the current adjustment switching element 771 from the following state: the voltage between the first terminal (collector terminal) 771a and the second terminal (emitter terminal) 771b is the specified threshold value V. TH Above and the drive circuit 94 has turned off the current adjustment switching element 771.

[0115] In addition, in the control device 90 of the first embodiment, the connection determination unit 95 determines the connection state between the current adjustment switch element 771 and the current limiting resistor 773 based on the determination result of the voltage determination circuit 92 in the cut-off control state. In the cut-off control state, the control drive circuit 94 is controlled to turn off the current adjustment switch element 771.

[0116] Therefore, according to the first embodiment, by only providing the voltage determination circuit 92, the voltage supply circuit 93, and the drive circuit 94 in the control device 90 and causing the connection determination unit 95 to perform a predetermined process, the connection state between the current adjustment switch element 771 and the control device 90 can be determined. For example, the presence or absence of disconnection of the signal lines and wires 81a to 81c between the current adjustment switch element 771 and the control device 90 and the detachment of the two connectors 83a and 83b can be determined. Therefore, special processing such as covering the wires 81a to 81c between the current adjustment switch element 771 and the control device 90 with wire materials does not need to be performed, and thus the manufacturing cost can be reduced.

[0117] In addition, after maintenance by the maintenance personnel, by causing the connection determination unit 95 to perform Figure 6 the operation shown, the detachment of the two connectors 83a and 83b due to human error during the maintenance by the maintenance personnel can be detected. Therefore, the labor and time for visual confirmation can be reduced. Since it is not necessary to analyze the captured image of the camera, the equipment cost can be reduced.

[0118] In addition, since the current adjustment switch element 771 and the connection determination unit 95 are insulated from each other by the first optocoupler to the fourth optocoupler 928, 936, 937, and 945, noise does not propagate from the current adjustment switch element 771 to the connection determination unit 95.

[0119] (Second Embodiment)

[0120] Figure 10 The structure of the AC-DC conversion circuit 72 and the control device 90 in the second embodiment is shown. In the second embodiment, the control device 90 has a circuit unit 91 for each of the switching elements 72a to 72d of the AC-DC conversion circuit 72.

[0121] The connection determination unit 95 performs the same control on the voltage supply signal S2 and the conduction cut-off signal S3 respectively input to the four circuit units 91 as the control shown in S101 to S107 of the first embodiment ( Figure 6 ).

[0122] In addition, the connection determination unit 95 determines the connection state between each of the switching elements 72a to 72d and the control device 90. Since no current-limiting resistors are connected in parallel to the switching elements 72a to 72d, the determination unit 953 of the connection determination unit 95 determines whether the second determination signal S1b corresponding to each circuit unit 91 is at a high level or a low level. When the second determination signal S1b is at a high level, the determination unit 953 can determine that there is no connection defect between the corresponding switching element 72a to 72d and the control device 90. When the second determination signal S1b is at a low level, the determination unit 953 can determine that there is a connection defect between the corresponding switching element 72a to 72d and the control device 90.

[0123] Since the other structures and effects are the same as those of the first embodiment, the same reference numerals are assigned to the same structures and their detailed descriptions are omitted.

[0124] It should be noted that the resistance values of the resistors included in the circuit unit 91, the capacitance values of the capacitors, the standby times in steps S102 and S105, and the voltages of each unit are not limited to the examples of the first embodiment and the second embodiment. For example, in the first embodiment, as long as the resistance values of the resistors included in the circuit unit 91, the capacitance values of the capacitors, and the standby times in steps S102 and S105 are set such that the first determination signal S1a and the second determination signal S1b become high levels when there is no connection defect, the first determination signal S1a becomes low level and the second determination signal S1b becomes high level when there is a connection defect between the current adjustment switching element 771 and the current-limiting resistor 773, and the first determination signal S1a and the second determination signal S1b become low levels when there is a connection defect between the current adjustment switching element 771 and the control device 90, other values are also possible.

[0125] In addition, the circuit structure of the circuit unit 91 is not limited to the examples of the first embodiment and the second embodiment. For example, in the first embodiment, as long as the combination of the first determination signal S1a and the second determination signal S1b is different when there is no connection defect, when there is a connection defect between the current adjustment switching element 771 and the current-limiting resistor 773, and when there is a connection defect between the current adjustment switching element 771 and the control device 90, the circuit structure of the circuit unit 91 can also be other structures.

[0126] -Industrial Applicability-

[0127] The control device of the present disclosure and the power supply device including the control device can both suppress the manufacturing cost and determine the connection state between the switching element and the control device, and are useful as a control device connected to the switching element and a power supply device including the control device.

[0128] -Symbol Explanation-

[0129] 3 Welding wire

[0130] 7 Power supply device

[0131] 72 AC / DC conversion circuit

[0132] 72a Upper-arm switching element

[0133] 72b Lower-arm switching element

[0134] 72c Upper-arm switching element

[0135] 72d Lower-arm switching element

[0136] 74 Insulation transformer

[0137] 75 Second rectification circuit

[0138] 771 Switching element for current adjustment

[0139] 771a Collector terminal (first terminal)

[0140] 771b Emitter terminal (second terminal)

[0141] 771c Gate terminal (third terminal)

[0142] 773 Current-limiting resistor

[0143] 92 Voltage determination circuit

[0144] 921 First resistor (resistive component)

[0145] 922 Second resistor (resistive component)

[0146] 938 Voltage supply capacitor

[0147] 94 Drive circuit

[0148] 95 Connection determination section

[0149] V TH Specified threshold value

[0150] PS AC power supply.

Claims

1. A control device is connected to a switching element. The switching element has a first terminal, a second terminal, and a third terminal. The third terminal controls the flow of current between the first terminal and the second terminal. It is characterized in that: The control device includes a capacitor, a drive circuit, a voltage determination circuit, and a connection determination unit. The capacitor is connected between the first terminal and the second terminal and can discharge toward the first terminal. The drive circuit is connected to the second terminal and the third terminal. The drive circuit turns the switching element on and off. The voltage determination circuit determines whether the voltage between the first terminal and the second terminal is equal to or higher than a specified threshold value. The connection determination unit performs conduction control and determines the connection state between the switching element and the control device based on the determination result of the voltage determination circuit after a specified time has elapsed since the conduction control. In the conduction control, the connection determination unit controls the drive circuit to turn on the switching element from a state where the voltage between the first terminal and the second terminal is equal to or higher than the specified threshold value and the drive circuit has turned off the switching element.

2. The control device according to claim 1, characterized in that: A current-limiting resistor is connected between the first terminal and the second terminal. The voltage determination circuit has a resistance component connected between the first terminal and the second terminal and having a resistance value larger than that of the current-limiting resistor. The connection determination unit determines the connection state between the switching element and the current-limiting resistor based on the determination result of the voltage determination circuit in the cut-off control state. In the cut-off control state, the connection determination unit controls the drive circuit to turn off the switching element.

3. The control device according to claim 1, characterized in that: The switching element and the connection determination unit are insulated from each other.

4. A power supply device includes the control device according to claim 1 and the switching element. It is characterized in that: The power supply device further includes a direct / alternating current conversion circuit, an isolation transformer, and a rectification circuit. The direct / alternating current conversion circuit generates a first alternating voltage using the power from an alternating current power supply. The isolation transformer converts the first alternating voltage generated by the direct / alternating current conversion circuit into a second alternating voltage and outputs the second alternating voltage. The rectification circuit rectifies the output of the isolation transformer. The switching element outputs a welding current by adjusting the output of the rectification circuit.

5. A power supply device includes the control device according to claim 1. It is characterized in that: The power supply device further includes a direct / alternating current conversion circuit, an isolation transformer, and a rectification circuit. The direct / alternating current conversion circuit has a plurality of the switching elements. The direct / alternating current conversion circuit generates a first alternating voltage using the power from an alternating current power supply through the switching actions of the plurality of switching elements. The isolation transformer converts the first alternating voltage generated by the direct / alternating current conversion circuit into a second alternating voltage and outputs the second alternating voltage. The rectifying circuit rectifies the output of the insulating transformer. The control device includes the capacitor, the drive circuit, and the voltage determination circuit for each of the switching elements. The connection determination unit determines the connection state between the switching element and the control device for each of the switching elements.

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