JPWO2006115020A1 - Welding machine - Google Patents

Abstract

In a full-bridge inverter circuit, first to fourth switching elements, first to fourth reverse diodes connected in parallel to each switching element, a power conversion transformer, and a rectifier that rectifies an output on the secondary side And an output detector for detecting the output, an error amplifying unit for amplifying an error between the signal from the output detector and the output setting signal, a first driver for controlling the first and second switching elements, And a second drive unit that controls the third and fourth switching elements, and a drive circuit that sends an on / off control signal to the first drive unit and the second drive unit at different timings. To do.

Description

  The present invention relates to an apparatus for generating an arc, and particularly to a welding machine equipped with an inverter circuit.

  In recent years, in order to reduce the size and performance of an apparatus, a power control circuit equipped with an inverter circuit capable of high-speed switching has become common, and inverter-controlled welding machines have become widespread.

  Conventional inverter-controlled welding machines are provided with a full-bridge or half-bridge inverter circuit using a power semiconductor such as IGBT or MOSFET. Then, the switching element is controlled at an inverter frequency of about several kHz to 100 kHz using partial resonance type control to obtain output current characteristics and output voltage characteristics. Such a technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-322189.

  Some inverter control methods are controlled by pulse width modulation (hereinafter abbreviated as “PWM”).

  FIG. 10 is a block diagram showing a circuit configuration of a conventional welding machine. First, a conventional welding machine having a partial resonance control function will be described with reference to FIG.

  In FIG. 10, a first switching circuit 131 and a second switching circuit 132 are connected in parallel between output terminals of a first rectifier 101 that rectifies a three-phase or single-phase AC input. The first switching circuit 131 is configured by connecting a first switching element 102 and a second switching element 104 in series. A connection point between the first switching element 102 and the second switching element 104 is a circuit output terminal 133 of the first switching circuit 131. In addition, a first reverse diode 103 and a second reverse diode 105 are connected in parallel to the first switching element 102 and the second switching element 104, respectively. The second switching circuit 132 is configured by connecting the third switching element 106 and the fourth switching element 108 in series. A connection point between the third switching element 106 and the fourth switching element 108 is a circuit output terminal 134 of the second switching circuit 132. In addition, a third reverse diode 107 and a fourth reverse diode 109 are connected in parallel to the third switching element 106 and the fourth switching element 108, respectively. A primary coil of the power conversion transformer 110 is connected between the circuit output terminals 133 and 134. The secondary coil of the transformer 110 is connected to a second rectifier 111 that rectifies the output. The output of the second rectifying unit 111 is connected to the output terminals 113 and 114 of the welding machine. The current rectified by the second rectification unit 111 is supplied to the arc load unit through the output terminals 113 and 114. In FIG. 10, one of the outputs of the second rectifier 111 is connected to the output terminal 114 via the output current detector 112. The output current is detected by the output current detector 112, and an output signal proportional to the output current is input from the output current detector 112 to the error amplifying unit 115. The error amplifier 115 receives the output signal of the output current detector 112 and outputs an error amplified signal Ve that is amplified by comparing the error with the output setting signal Vr. The drive circuit 116 receives the error amplification signal Ve and outputs control signals S1 and S2 that change the operation timing according to the error amplification signal Ve to the first drive unit 117 and the second drive unit 118, respectively. In response to the output signal from the driving circuit 116, the first driving unit 117 outputs a switching signal for controlling on / off of the first switching element 102 and the second switching element 104 at different timings. The drive unit 118 outputs a switching signal for performing on / off control of the third switching element 106 and the fourth switching element 108 at different timings. As described above, a conventional welding machine is configured.

  Next, the operation of the conventional welding machine will be specifically described.

  FIG. 11 is a timing chart showing inverter operation by partial resonance control of a conventional welding machine. The upper four waveforms in FIG. 11 show the waveforms of the input switching signals of the first to fourth switching elements 102, 104, 106, and 108, respectively. A period indicated by hatching indicates a period during which the first to fourth switching elements are turned on, and the other periods indicate an off state. The bottom waveform in FIG. 11 shows the primary current waveform of the transformer 110. Here, the first direction indicates a direction in which a current flowing through the primary coil of the transformer 110 flows from the circuit output terminal 133 toward the circuit output terminal 134. The second direction is the opposite direction of the first direction.

  As shown in FIG. 11, the first switching element 102 and the second switching element 104 perform on / off control switching alternately, and the third switching element 106 and the fourth switching element 108 alternate. Performs on / off control switching. In the case of outputting a low current, the on-period of the first switching element 102 and the fourth switching element 108 overlaps and the on-period of the second switching element 104 and the third switching element 106. Reduce the time that overlaps. Similarly, in the case of outputting a high current, the time during which the respective ON periods overlap is lengthened.

  In the welding machine configured as described above, in the control by the partial resonance type, as shown in FIG. 11, two switching elements are always in conduction among the switching elements. For this reason, the back electromotive voltage generated in the transformer 110 is quickly regenerated in a bridge (hereinafter abbreviated as “bridge”) composed of switching elements and reverse diodes of the first switching circuit 131 and the second switching circuit 132. can do. For this reason, it has the characteristic that the surge voltage applied to each switching element is suppressed.

  Next, as another example of a conventional welding machine, a welding machine having a PWM control function will be described with reference to FIG.

  Since the PWM-controlled welding machine has the same configuration as that shown in FIG. 10, the control by PWM will be described using the configuration of the welding machine shown in FIG. 10, and description of each part of the components will be omitted.

  FIG. 12 is a timing chart showing inverter operation by PWM control of a conventional welder. In the control by PWM, as shown in FIG. 12, for the low current output setting, the ON time of the first to fourth switching elements 102, 104, 106, and 108 (hereinafter abbreviated as “switching ON time”). ) To shorten the output current. For high current output setting, the output current can be increased by increasing the ON time of the switching element. Further, since each switching element performs on / off control switching at the same timing, the current to the reverse diode is reduced when the switching element is turned off. For this reason, the heat generation of the reverse diode is suppressed.

  In addition, although described about what performs constant current control as a conventional welding machine, when performing constant voltage control, instead of the output current detector 112, the output voltage which detects the output voltage between the output terminals 113 and 114 is described. The detector is used as an output detector. Then, error amplifier 115 compares the voltage setting value with the output signal from the output voltage detector, and outputs error amplified signal Ve to drive circuit 116. With such a configuration, constant voltage control can be performed as a conventional welding machine.

  In the conventional partial resonance type welding machine as described above, the counter electromotive voltage generated in the transformer 110 is quickly regenerated in the bridge, but the current flowing through the reverse diodes connected in parallel to the respective switching elements constituting the bridge is generated. There is a problem of increasing. In general, a switching element and a reverse diode are connected in parallel and mounted as a power semiconductor in the same package. For example, the first switching element 102 and the first reverse diode 103 are mounted in the same package to form one power semiconductor. When the current flowing through the reverse diode increases, the amount of heat generated by the power semiconductor increases. Further, since the thermal resistance of the reverse diode is higher than that of the switching element, there is a restriction that heat dissipation must be strengthened in order to prevent the temperature breakdown of the power semiconductor.

  In the conventional PWM type welding machine, there is a period in which the switching elements are simultaneously turned off. For this reason, a surge voltage is generated due to a high surge voltage or a counter electromotive voltage of the transformer 110 when the switching element is turned off at the same time when a high current is flowing. In order to prevent the destruction of the switching element due to such a surge voltage, there is a restriction that a snubber circuit must be added to each switching element. Alternatively, in order to regenerate the back electromotive voltage in the first rectification unit, there is a restriction that the first rectification unit must be arranged in the vicinity of the switching element.

  The welding machine of the present invention includes a first rectifying unit that rectifies an AC power input, a first switching element connected between the outputs of the first rectifying unit and a first reverse diode connected in parallel. A first switching circuit configured in series connection with a second switching element in which two reverse diodes are connected in parallel, and a third reverse diode connected in parallel between the outputs of the first rectifying unit A second switching circuit constituted by a series connection of a third switching element connected and a fourth switching element connected in parallel by a fourth reverse diode, and one of the primary side coils is the first switching A transformer connected to the connection between the element and the second switching element, the other end of the primary coil being connected to the connection between the third switching element and the fourth switching element, and 2 of the transformer A second rectifier that rectifies the output from the side coil, an output detector that detects the output of the second rectifier, and an error amplifier that amplifies the error between the output signal from the output detector and the output setting signal A driving circuit that varies a timing at which a control signal is output in accordance with an error amplification signal from an error amplification unit, a first switching element and a second switching element that receive the control signal, A first drive unit that outputs a switching signal that drives the second switching unit; and a second drive unit that outputs a switching signal that inputs the control signal and drives the third switching element and the fourth switching element. The second drive unit is configured to switch the fourth switch at a timing different from the timing at which the first drive unit outputs a switching signal for switching the first switching element from the on state to the off state. And a third timing at a timing different from a timing at which the first drive unit outputs a switching signal for switching the second switching element from the on state to the off state. The switching element is provided with at least one of a configuration for outputting a switching signal for switching the switching element from an on state to an off state.

  Moreover, the welding machine of this invention is the 1st switching element connected between the 1st rectification part which rectifies | straightens an alternating current power supply input, and the output of a 1st rectification part, and the 1st reverse diode was connected in parallel. And a third switching diode connected between the outputs of the first rectifying unit and a first switching circuit configured in series with a second switching element in which a second switching diode is connected in parallel Is connected in series with a third switching element and a fourth switching element with a fourth reverse diode connected in parallel, and one of the primary side coils is the first switching coil. A transformer connected to the connection between the first switching element and the second switching element, the other end of the primary coil being connected to the connection between the third switching element and the fourth switching element, and a transformer. A second rectifying unit that rectifies the output from the secondary side coil, an output detector that detects the output of the second rectifying unit, and an error between the output signal from the output detector and the output setting signal In a welding machine including an error amplification unit, a control signal is output to the first drive unit, the second drive unit, the third drive unit, and the fourth drive unit in accordance with an error amplification signal from the error amplification unit. The first driving unit outputs a switching signal for driving the first switching element, and the third driving unit performs the second switching at a timing different from that of the first driving unit. The second driving unit is configured to output a switching signal for driving the element, and the second driving unit has a timing different from that at which the first driving unit outputs a switching signal for switching the first switching element from the on state to the off state. First The fourth drive unit outputs a switching signal for switching the second switching element from the on state to the off state, and the fourth driving unit outputs the switching signal for switching the switching element from the on state to the off state. The drive circuit includes at least one of a configuration for outputting a switching signal for switching the third switching element from an on state to an off state at a timing different from the above.

  Furthermore, the welding machine according to the present invention includes a first switching element connected between a first rectifying unit that rectifies an AC power input and an output of the first rectifying unit, and a first reverse diode connected in parallel. And a third switching diode connected between the outputs of the first rectifying unit and a first switching circuit configured in series with a second switching element in which a second switching diode is connected in parallel Is connected in series with a third switching element and a fourth switching element with a fourth reverse diode connected in parallel, and one of the primary side coils is the first switching coil. A transformer connected to the connection between the switching element and the second switching element and the other side of the primary coil connected to the connection between the third switching element and the fourth switching element; A second rectifier that rectifies the output from the secondary coil of the power supply, an output detector that detects the output of the second rectifier, and an error between the output signal from the output detector and the output setting signal A welding circuit including an error amplification unit that includes a drive circuit that varies a timing at which a control signal is output to the fifth drive unit and the sixth drive unit according to an error amplification signal from the error amplification unit; The driving unit 5 outputs switching signals for driving the first switching element and the fourth switching element, respectively, and the sixth driving unit outputs the second signal at a timing different from the timing of the fifth driving unit. A switching signal for driving the switching element and the third switching element is output, and the switching signal for switching the first switching element from the on state to the off state is output. The fifth drive unit outputs a switching signal for switching the fourth switching element from the on state to the off state at a timing different from the timing, and outputs a switching signal for switching the second switching element from the on state to the off state And a configuration in which the sixth drive unit outputs a switching signal for switching the third switching element from the on state to the off state at a timing different from the timing at which the third driving element is turned on. .

FIG. 1 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 1 of the present invention. FIG. 2 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 2 of the present invention. FIG. 3 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 3 of the present invention. FIG. 4 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 4 of the present invention. FIG. 5 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 5 of the present invention. FIG. 6 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 6 of the present invention. FIG. 7 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 7 of the present invention. FIG. 8 is a block diagram showing a circuit configuration of the welding machine according to the eighth embodiment of the present invention. FIG. 9 is a timing chart showing the inverter operation of the welding machine of the present invention. FIG. 10 is a block diagram showing a circuit configuration of a conventional welding machine. FIG. 11 is a timing chart showing inverter operation by partial resonance control of a conventional welding machine. FIG. 12 is a timing chart showing inverter operation by PWM control of a conventional welder.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,101 1st rectifier 2,102 1st switching element 3,103 1st reverse diode 4,104 2nd switching element 5,105 2nd reverse diode 6,106 3rd switching element 7, 107 Third reverse diode 8, 108 Fourth switching element 9, 109 Fourth reverse diode 10, 110 Transformer 11, 111 Second rectifier 12, 112 Output current detector 13, 14, 113, 114 Output terminal 15, 115 Error amplifiers 16, 116, 216, 316 Drive circuits 17, 117 First drive units 18, 118, 218 Second drive unit 19 First delay circuit 20 Logic integrated circuit 21 Third drive unit 22 , 222 Fourth driving unit 23 Second delay circuit 24, 224 Fifth driving unit 25, 225 Sixth driving unit 31, 131 First switching Circuit 32, 132 Second switching circuit 33, 34, 133, 134 Circuit output terminal Vr Output setting signal Ve Error amplification signal S1, S2, S3, S4, S5, S6 Control signal

(Embodiment 1)
FIG. 1 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 1 of the present invention. In FIG. 1, a first switching circuit 31 and a second switching circuit 32 are connected in parallel between output terminals of a first rectifying unit 1 that rectifies a three-phase or single-phase AC input. The first switching circuit 31 is configured by connecting the first switching element 2 and the second switching element 4 in series. A connection point between the first switching element 2 and the second switching element 4 is a circuit output terminal 33 of the first switching circuit 31. In addition, a first reverse diode 3 and a second reverse diode 5 are connected in parallel to the first switching element 2 and the second switching element 4, respectively. The second switching circuit 32 is configured by connecting the third switching element 6 and the fourth switching element 8 in series. The connection point is the circuit output terminal 34 of the second switching circuit 32. In addition, a third reverse diode 7 and a fourth reverse diode 9 are connected in parallel to the third switching element 6 and the fourth switching element 8, respectively. The primary coil of the power conversion transformer 10 is connected between the circuit output terminals 33 and 34. A primary current flows through the primary coil of the transformer 10 in the first direction via the first switching element 2 and the fourth switching element 8, and the second switching element 4 and the fourth switching element 8. And a primary current flows in a second direction opposite to the first direction.

  The secondary coil of the transformer 10 is connected to a second rectifying unit 11 that rectifies the output. The output of the 2nd rectification | straightening part 11 is connected to the output terminals 13 and 14 of a welding machine. The current rectified by the second rectifying unit 11 is supplied to the arc load unit through the output terminals 13 and 14. In FIG. 1, one of the outputs of the second rectifying unit 11 is connected to the output terminal 14 via the output current detector 12.

  The output current flowing to the load unit is detected by the output current detector 12, and an output signal proportional to the output current is input from the output current detector 12 to the error amplifying unit 15. The error amplifier 15 receives the output signal of the output current detector 12, compares the error with the output setting signal Vr, and outputs an amplified error amplified signal Ve. The drive circuit 16 receives the error amplification signal Ve and outputs control signals S1 and S2 that change the operation timing according to the error amplification signal Ve to the first drive unit 17 and the second drive unit 18, respectively. In response to the output signal from the drive circuit 16, the first drive unit 17 outputs a switching signal for controlling on / off of the first switching element 2 and the second switching element 4 at different timings. The drive unit 18 outputs a switching signal for performing on / off control of the third switching element 6 and the fourth switching element 8 at different timings. As described above, the welding machine that performs constant current control according to Embodiment 1 of the present invention is configured.

  The operation of the welding machine configured as described above will be described.

  FIG. 9 is a timing chart showing the operating states of the first to fourth switching elements 2, 4, 6, 8 and the primary current waveform of the transformer 10. As shown in FIG. 9, in order to reduce the output current value, the on-times of the first to fourth switching elements 2, 4, 6, 8 are shortened, and in order to increase the output current value, The drive circuit 16 outputs control signals S1 and S2 so as to increase the time. The first driving unit 17 outputs a switching signal at different timings to the first switching element 2 and the second switching element 4 in accordance with the control signal S1. And the 2nd drive part 18 outputs a switching signal with a different timing with respect to the 3rd switching element 6 and the 4th switching element 8 according to control signal S2. At this time, the first switching element 2 and the fourth switching element 8 are simultaneously turned on. Further, the first driving is performed so that the second switching element 4 and the third switching element 6 are simultaneously turned on at a timing different from the period during which the first switching element 2 and the fourth switching element 8 are turned on. The unit 17 and the second driving unit 18 output a switching signal.

  Further, after the first switching element 2 is switched to the off state, the fourth switching element is delayed by a predetermined time until the switching surge current generated by the first switching element 2 being turned off disappears. 8 switches to the off state. In addition, after the second switching element 4 is switched to the OFF state, the third switching is delayed by a predetermined time until the switching surge current generated when the second switching element 4 is turned OFF disappears. Element 6 switches to the off state. The 1st drive part 17 and the 2nd drive part 18 output a switching signal so that it may become such a sequence. In this way, the timing for switching the fourth switching element 8 to the OFF state is delayed until the switching surge current of the first switching element 2 disappears. Thereby, after the first switching element 2 is switched to the OFF state, a change occurs in the current flowing in the primary side coil of the transformer 10 in the first direction, and the back electromotive voltage generated in the transformer 10 starts to decrease. It is regenerated within. This is because a current path through which the switching surge current flows in the first direction in the primary coil of the transformer 10 through the fourth switching element 8 and the second reverse diode 5 is formed. Further, when the fourth switching element 8 is switched to the OFF state, the surge voltage is suppressed because the switching surge current flowing in the primary side coil of the transformer 10 has almost disappeared. Further, since the regenerative time in the bridge, that is, the predetermined time until the switching surge current of the first switching element 2 disappears (for example, several tens of nanoseconds to several hundreds of nanoseconds) is short, the current flows through the second reverse diode 5. Since the current has a minute value, heat generation of the power semiconductor (including the second switching element 4 and the second reverse diode 5) is suppressed.

  Similarly, the timing for switching the third switching element 6 to the OFF state is delayed until the switching surge current of the second switching element 4 disappears. As a result, after the second switching element 4 is switched to the OFF state, a change occurs in the current flowing through the primary coil of the transformer 10 in the second direction, and the back electromotive voltage generated in the transformer 10 starts to decrease, and the bridge It is regenerated within. This is because the current path through which the switching surge current flows in the second direction in the primary coil of the transformer 10 through the first reverse diode 3 and the third switching element 6 is formed. When the third switching element 6 is switched to the OFF state, the surge voltage is suppressed because the switching surge current flowing in the primary coil of the transformer 10 has almost disappeared. In addition, since the regenerative time in the bridge, that is, the predetermined time (several tens of nsec to several hundred nsec) until the switching surge current of the second switching element 4 disappears is short, the current flowing through the first reverse diode 3 is Since it becomes minute, heat generation of the power semiconductor (including the first switching element 2 and the first reverse diode 3) is suppressed.

  As described above, according to the welding machine of the present embodiment, the on / off state switching timing of each switching element is performed at the same time as the on state, and the timing of switching to the off state is delayed. . With this configuration, it is possible to suppress the current to the reverse diodes 3 and 5. For this reason, it is possible to suppress the heat generation of the power semiconductor including the reverse diodes 3 and 5, regenerate the counter electromotive voltage generated in the transformer 10, and suppress the surge voltage applied to the switching elements 6 and 8. .

  When the switching element is suddenly switched to the OFF state in a state where a high current value is flowing through the switching element, the current rapidly decreases and a surge voltage is generated due to an inductance component of the circuit. A surge voltage is also generated by a counter electromotive voltage generated in the transformer 10.

  In addition, although the welding machine which performs constant current control was described here, when performing constant voltage control, it replaces with the output current detector 12 as an output detector, and detects the voltage between the output terminals 13 and 14. An output voltage detector is provided. The output signal from the output voltage detector is input to the error amplifying unit 15. The error amplification unit 15 may be configured to output the error amplification signal Ve by comparing the output setting signal Vr with the output signal from the output voltage detector.

  In FIG. 9, the timing relationship for switching the first switching element 2 and the fourth switching element 8 to the OFF state may be opposite to that described above. That is, after the fourth switching element 8 is switched to the OFF state, the first switching element 2 may be switched to the OFF state after the back electromotive voltage generated in the transformer 10 is regenerated in the bridge. Similarly, the timing relationship for switching the second switching element 4 and the third switching element 6 to the OFF state may be opposite to the above. Furthermore, the timing relationship for switching the first switching element 2 and the fourth switching element 8 to the OFF state is different from the timing relationship for switching the second switching element 4 and the third switching element 6 to the OFF state. Needless to say.

  Examples of power semiconductors including switching elements and reverse diodes include IGBTs (insulated gate bipolar transistors), MOSFETs (oxide semiconductor field effect transistors), and IPMs (intelligent power modules). In the IGBT or MOSFET, the first switching element 2 and the first reverse diode 3, the second switching element 4 and the second reverse diode 5, the third switching element 6 and the third reverse diode 7, and the fourth With the combination of the switching element 8 and the fourth reverse diode 9, each switching element and the reverse diode connected in parallel with each other are configured in one IGBT package. For this reason, when IGBT is used, it is not necessary to add the reverse diode connected in parallel with the switching element. The same applies to MOSFETs. However, some MOSFETs do not include a reverse diode. In this case, it is necessary to add a reverse diode to the outside. In the IPM, the first to fourth switching elements 2, 4, 6, 8 and the first to fourth reverse diodes 3, 5, 7, 9 are formed in one IPM package. For this reason, when IPM is used, it is not necessary to add an external reverse diode connected in parallel to the switching element.

  With such a configuration, the heat generation of the power semiconductor is suppressed by suppressing the current to the reverse diode, and the surge voltage applied to the switching element is suppressed by regenerating the counter electromotive voltage generated in the transformer 10. A high-performance welder can be realized.

  In the first embodiment, regarding the timing of switching each switching element from the on state to the off state, the difference in timing relationship between the first switching element and the fourth switching element, or the second switching element and the second switching element. Only one of the differences in timing relationship with the three switching elements may be used. In that case, the same effect can be obtained for the switching element having a different timing relationship.

(Embodiment 2)
FIG. 2 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 2 of the present invention. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. 2 is different from the first embodiment in that a first delay circuit 19 is provided in the second drive unit 218. FIG.

  In the welding machine shown in FIG. 2, in the configuration in which the control signal S1 from the drive circuit 16 to the first drive unit 17 and the control signal S2 to the second drive unit 218 are output at the same timing, The first delay circuit 19 delays the timing of outputting the switching signal for switching the fourth switching element 8 to the OFF state until a predetermined time when the switching surge current generated in the first switching element 2 disappears, and the third delay circuit 19 The timing for outputting the switching signal for switching the switching element 6 to the OFF state can be delayed until a predetermined time when the switching surge current generated in the second switching element 4 disappears.

  The configuration of the first delay circuit 19 includes a configuration in which the delay time is changed by a timer using an integrated circuit, and a delay time in which the charge / discharge time is changed by changing the constants of resistors and capacitors using a time constant circuit. The structure etc. which change can be used.

  In the second embodiment, the fourth switching element is delayed with respect to the first switching element and the third switching element is set to the second timing with respect to the timing of switching each switching element from the on state to the off state. The example which delays with respect to a switching element was shown. However, the present invention is not limited to this, and the timing may be delayed only by either the fourth switching element or the third switching element, and the same effect can be obtained for the switching element whose timing is delayed. .

  With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.

(Embodiment 3)
FIG. 3 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 3 of the present invention. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 3, the difference from the first embodiment is that a logic integrated circuit 20 is configured in the drive circuit 216.

  In FIG. 3, a program for outputting a drive signal S1 to the first drive unit 17 and a drive signal S2 to the second drive unit 18 is stored in the logic integrated circuit 20 of the drive circuit 216. ing. Thus, the output timing of the control signal S2 for switching the fourth switching element 8 to the OFF state is delayed until a predetermined time when the switching surge current generated in the first switching element 2 disappears, and the third switching element 6 The output timing of the control signal S2 for switching to the OFF state can be delayed until a predetermined time when the switching surge generated in the second switching element 4 disappears.

  Note that the logic integrated circuit 20 is one that rewrites internal logic such as a CPU (Central Processing Unit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), and the like.

  With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.

(Embodiment 4)
FIG. 4 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 4 of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 4, the difference from the first embodiment is that the drive circuit 316 outputs four signals S3, S4, S5, and S6, which are respectively output to the first drive unit 17, the second drive unit 18, and the third drive unit 316. The signals are input to the drive unit 21 and the fourth drive unit 22. Then, the outputs of the first drive unit 17, the second drive unit 18, the third drive unit 21, and the fourth drive unit 22 are converted into the first switching element 2, the fourth switching element 8, and the second output, respectively. The switching element 4 and the third switching element 6 are input. Thus, the first drive unit 17 provides the first switching element 2, the second drive unit 18 provides the fourth switching element 8, the third drive unit 21 provides the second switching element 4, The fourth drive unit 22 controls the third switching element 6. The difference from the first embodiment is that a driving unit is provided for each switching element, and the switching elements can be independently controlled.

  In FIG. 4, the control signal S3 for turning on the first and fourth switching elements from the drive circuit 316 to the first drive unit 17 and the second drive unit 18 at the same timing, respectively. Send S4. Then, when the ON period has passed, the drive circuit 316 sends a control signal S3 for turning off the first switching element 2 to the first drive unit 17. Thereafter, a control signal for turning off the fourth switching element 8 with respect to the second drive unit 18 at a timing delayed until a predetermined time when the switching surge current generated in the first switching element 2 disappears. Send S4. Similarly, control signals S5 and S6 for turning on the second and third switching elements are respectively sent from the drive circuit 316 to the third drive unit 21 and the fourth drive unit 22 at the same timing. . Then, when the ON period has passed, the drive circuit 316 sends a control signal S5 for turning off the second switching element 4 to the third drive unit 21. Thereafter, a control signal for turning off the third switching element 6 with respect to the fourth drive unit 22 at a timing delayed until a predetermined time when the switching surge current generated in the second switching element 4 disappears. Send S6.

  With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.

  In the fourth embodiment, regarding the timing of switching each switching element from the on state to the off state, the difference in timing relationship between the first switching element and the fourth switching element, or the second switching element and the second switching element. Only one of the differences in timing relationship with the three switching elements may be used. In that case, the same effect can be obtained for the switching element having a different timing relationship.

(Embodiment 5)
FIG. 5 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 5 of the present invention. In the present embodiment, the same components as those in the fourth embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 5, the difference from the fourth embodiment is that the first delay circuit 19 is configured inside the second drive unit 218 and the second delay circuit 23 is configured inside the fourth drive unit 222. Is a point.

  In the welding machine shown in FIG. 5, the control signal S3 from the drive circuit 316 to the first drive unit 17 and the control signal S4 to the second drive unit 218 are output at the same timing, and the third The control signal S5 to the drive unit 21 and the control signal S6 to the fourth drive unit 222 are output at the same timing. At this time, the first switching element 2 generates a timing for outputting a switching signal for switching the fourth switching element 8 from the on state to the off state by the first delay circuit 19 and the second delay circuit 23. Delay until a predetermined time until the switching surge current disappears. At the same time, the timing for outputting the switching signal for switching the third switching element 6 from the on state to the off state is delayed until a predetermined time when the switching surge current generated in the second switching element 4 disappears.

  Note that the delay circuits 19 and 23 are configured by using an integrated circuit to form a timer and changing the delay time, or by changing the constants using a time constant circuit composed of a resistor and a capacitor, thereby reducing the charge / discharge time. There are means for changing the delay time by changing.

  With such a configuration, similarly to the fourth embodiment, it is possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.

(Embodiment 6)
FIG. 6 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 6 of the present invention. In the present embodiment, the same components as those in the fourth embodiment are denoted by the same reference numerals and detailed description thereof is omitted. 6 differs from the fourth embodiment in that a logic integrated circuit 20 is configured in the drive circuit 216. FIG.

  In FIG. 6, the control signal S3 from the drive circuit 216 to the first drive unit 17, the control signal S4 to the second drive unit 18, the control signal S5 to the third drive unit 21, and the fourth The control signal S6 to the drive unit 22 is controlled by a program stored in the logic integrated circuit 20. Accordingly, the timing at which the second drive unit 18 outputs the switching signal for switching the fourth switching element 8 from the on state to the off state is set to a predetermined time when the switching surge current generated in the first switching element 2 disappears. Delay. At the same time, the timing at which the fourth drive unit 22 outputs the switching signal for switching the third switching element 6 from the on state to the off state is delayed until a predetermined time at which the switching surge current generated in the second switching element 4 disappears. .

  With such a configuration, the heat generation of the power semiconductor is suppressed by suppressing the current to the reverse diode, and the surge voltage applied to the switching element is suppressed by regenerating the counter electromotive voltage generated in the transformer 10. A high-performance welder can be realized.

  As the logic integrated circuit 20, a circuit, such as a CPU, PLD, FPGA, DSP, which rewrites the internal theory is used.

(Embodiment 7)
FIG. 7 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 7 of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 7, the fifth driving unit 24 outputs a switching signal to the first switching element 2 and the fourth switching element 8, and the sixth driving unit 25 is different from the first embodiment in that the fifth driving unit 24 outputs the switching signal. The switching signal is output to the switching element 4 and the third switching element 6.

  At this time, the first switching element 2 and the fourth switching element 8 are simultaneously switched on, and the second switching element 4 and the third switching element 6 are simultaneously turned on at a timing different from this timing. Switching signals are output from the fifth driving unit 24 and the sixth driving unit 25 so as to switch to the state. After a predetermined on period, the fifth drive unit 24 outputs a switching signal for switching the first switching element 2 to the off state. Then, after delaying until a predetermined time when the switching surge current generated in the first switching element 2 disappears, a switching signal for switching the fourth switching element 8 to the OFF state is output from the fifth drive unit 24. On the other hand, after a predetermined on period, the sixth drive unit 25 outputs a switching signal for switching the second switching element 4 to the off state. Then, after delaying until a predetermined time when the switching surge current generated in the second switching element 4 disappears, a switching signal for switching the third switching element 6 to the OFF state is output from the sixth drive unit 25.

  With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.

  In the seventh embodiment, regarding the timing of switching each switching element from the on state to the off state, the difference in timing relationship between the first switching element and the fourth switching element, or the second switching element and the second switching element. Only one of the differences in timing relationship with the three switching elements may be used. In that case, the same effect can be obtained for the switching element having a different timing relationship.

(Embodiment 8)
FIG. 8 is a block diagram showing a circuit configuration of the welding machine according to the eighth embodiment of the present invention. In the present embodiment, the same components as those in the seventh embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 8, the difference from the seventh embodiment is that the first delay circuit 19 is configured in the fifth drive unit 224. The second delay circuit 23 is configured inside the sixth drive unit 225.

  In the welding machine shown in FIG. 8, the control signal S <b> 1 output from the drive circuit 16 is input to the fifth drive unit 224. The timing at which the fifth driving unit 224 outputs the switching signal for switching the fourth switching element 8 to the OFF state after outputting the switching signal for switching the first switching element 2 to the OFF state is set to the first switching element. 2 can be delayed by the first delay circuit 19 until the switching surge current generated in 2 disappears.

  Similarly, the control signal S <b> 2 from the drive circuit 16 is input to the sixth drive unit 225. The timing at which the sixth drive unit 225 outputs the switching signal for switching the third switching element 6 to the OFF state after outputting the switching signal for switching the second switching element 4 to the OFF state is set to the second switching element. 4 can be delayed by the second delay circuit 23 until the switching surge current generated in 4 disappears.

  Note that the delay circuits 19 and 23 are configured by using an integrated circuit to form a timer and changing the delay time, or by changing the constants using a time constant circuit composed of a resistor and a capacitor, thereby reducing the charge / discharge time. There are means for changing the delay time by changing.

  With this configuration, as in the seventh embodiment, it is possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.

  The present invention suppresses the heat generation of the power semiconductor by suppressing the current to the reverse diode, and improves the reliability by suppressing the surge voltage applied to the switching element by regenerating the counter electromotive voltage generated in the transformer 10. A high welding machine can be realized, and the present invention is industrially useful as a device used in the welding industry and the industrial field in which a relatively large current output is handled and output is controlled.

[Document Name] Description
Name of invention Welding machine
【Technical field】
[0001]
The present invention relates to an apparatus for generating an arc, and particularly to a welding machine equipped with an inverter circuit.
[Background]
[0002]
In recent years, in order to reduce the size and performance of an apparatus, a power control circuit equipped with an inverter circuit capable of high-speed switching has become common, and inverter-controlled welding machines have become widespread.
[0003]
Conventional inverter-controlled welding machines are provided with a full-bridge or half-bridge inverter circuit using a power semiconductor such as IGBT or MOSFET. Then, the switching element is controlled at an inverter frequency of about several kHz to 100 kHz using partial resonance type control to obtain output current characteristics and output voltage characteristics. Such a technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-322189.
[0004]
Some inverter control methods are controlled by pulse width modulation (hereinafter abbreviated as “PWM”).
[0005]
FIG. 10 is a block diagram showing a circuit configuration of a conventional welding machine. First, a conventional welding machine having a partial resonance control function will be described with reference to FIG.
[0006]
In FIG. 10, a first switching circuit 131 and a second switching circuit 132 are connected in parallel between output terminals of a first rectifier 101 that rectifies a three-phase or single-phase AC input. The first switching circuit 131 is configured by connecting a first switching element 102 and a second switching element 104 in series. A connection point between the first switching element 102 and the second switching element 104 is a circuit output terminal 133 of the first switching circuit 131. In addition, a first reverse diode 103 and a second reverse diode 105 are connected in parallel to the first switching element 102 and the second switching element 104, respectively. The second switching circuit 132 is configured by connecting the third switching element 106 and the fourth switching element 108 in series. A connection point between the third switching element 106 and the fourth switching element 108 is a circuit output terminal 134 of the second switching circuit 132. In addition, a third reverse diode 107 and a fourth reverse diode 109 are connected in parallel to the third switching element 106 and the fourth switching element 108, respectively. A primary coil of the power conversion transformer 110 is connected between the circuit output terminals 133 and 134. The secondary coil of the transformer 110 is connected to a second rectifier 111 that rectifies the output. The output of the second rectifying unit 111 is connected to the output terminals 113 and 114 of the welding machine. The current rectified by the second rectification unit 111 is supplied to the arc load unit through the output terminals 113 and 114. In FIG. 10, one of the outputs of the second rectifier 111 is connected to the output terminal 114 via the output current detector 112. The output current is detected by the output current detector 112, and an output signal proportional to the output current is input from the output current detector 112 to the error amplifying unit 115. The error amplifier 115 receives the output signal of the output current detector 112 and outputs an error amplified signal Ve that is amplified by comparing the error with the output setting signal Vr. The drive circuit 116 receives the error amplification signal Ve and outputs control signals S1 and S2 that change the operation timing according to the error amplification signal Ve to the first drive unit 117 and the second drive unit 118, respectively. In response to the output signal from the driving circuit 116, the first driving unit 117 outputs a switching signal for controlling on / off of the first switching element 102 and the second switching element 104 at different timings. The drive unit 118 outputs a switching signal for performing on / off control of the third switching element 106 and the fourth switching element 108 at different timings. As described above, a conventional welding machine is configured.
[0007]
Next, the operation of the conventional welding machine will be specifically described.
[0008]
FIG. 11 is a timing chart showing inverter operation by partial resonance control of a conventional welding machine. The upper four waveforms in FIG. 11 show the waveforms of the input switching signals of the first to fourth switching elements 102, 104, 106, and 108, respectively. A period indicated by hatching indicates a period during which the first to fourth switching elements are turned on, and the other periods indicate an off state. The bottom waveform in FIG. 11 shows the primary current waveform of the transformer 110. Here, the first direction indicates a direction in which a current flowing through the primary coil of the transformer 110 flows from the circuit output terminal 133 toward the circuit output terminal 134. The second direction is the opposite direction of the first direction.
[0009]
As shown in FIG. 11, the first switching element 102 and the second switching element 104 perform on / off control switching alternately, and the third switching element 106 and the fourth switching element 108 alternate. Performs on / off control switching. In the case of outputting a low current, the on-period of the first switching element 102 and the fourth switching element 108 overlaps and the on-period of the second switching element 104 and the third switching element 106. Reduce the time that overlaps. Similarly, in the case of outputting a high current, the time during which the respective ON periods overlap is lengthened.
[0010]
In the welding machine configured as described above, in the control by the partial resonance type, as shown in FIG. 11, two switching elements are always in conduction among the switching elements. For this reason, the back electromotive voltage generated in the transformer 110 is quickly regenerated in a bridge (hereinafter abbreviated as “bridge”) composed of switching elements and reverse diodes of the first switching circuit 131 and the second switching circuit 132. can do. For this reason, it has the characteristic that the surge voltage applied to each switching element is suppressed.
[0011]
Next, as another example of a conventional welding machine, a welding machine having a PWM control function will be described with reference to FIG.
[0012]
Since the PWM-controlled welding machine has the same configuration as that shown in FIG. 10, the control by PWM will be described using the configuration of the welding machine shown in FIG. 10, and description of each part of the components will be omitted.
[0013]
FIG. 12 is a timing chart showing inverter operation by PWM control of a conventional welder. In the control by PWM, as shown in FIG. 12, for the low current output setting, the ON time of the first to fourth switching elements 102, 104, 106, and 108 (hereinafter abbreviated as “switching ON time”). ) To shorten the output current. For high current output setting, the output current can be increased by increasing the ON time of the switching element. Further, since each switching element performs on / off control switching at the same timing, the current to the reverse diode is reduced when the switching element is turned off. For this reason, the heat generation of the reverse diode is suppressed.
[0014]
In addition, although described about what performs constant current control as a conventional welding machine, when performing constant voltage control, instead of the output current detector 112, the output voltage which detects the output voltage between the output terminals 113 and 114 is described. The detector is used as an output detector. Then, error amplifier 115 compares the voltage setting value with the output signal from the output voltage detector, and outputs error amplified signal Ve to drive circuit 116. With such a configuration, constant voltage control can be performed as a conventional welding machine.
[0015]
In the conventional partial resonance type welding machine as described above, the counter electromotive voltage generated in the transformer 110 is quickly regenerated in the bridge, but the current flowing through the reverse diodes connected in parallel to the respective switching elements constituting the bridge is generated. There is a problem of increasing. In general, a switching element and a reverse diode are connected in parallel and mounted as a power semiconductor in the same package. For example, the first switching element 102 and the first reverse diode 103 are mounted in the same package to form one power semiconductor. When the current flowing through the reverse diode increases, the amount of heat generated by the power semiconductor increases. Further, since the thermal resistance of the reverse diode is higher than that of the switching element, there is a restriction that heat dissipation must be strengthened in order to prevent the temperature breakdown of the power semiconductor.
[0016]
In the conventional PWM type welding machine, there is a period in which the switching elements are simultaneously turned off. For this reason, a surge voltage is generated due to a high surge voltage or a counter electromotive voltage of the transformer 110 when the switching element is turned off at the same time when a high current is flowing. In order to prevent the destruction of the switching element due to such a surge voltage, there is a restriction that a snubber circuit must be added to each switching element. Alternatively, in order to regenerate the back electromotive voltage in the first rectification unit, there is a restriction that the first rectification unit must be arranged in the vicinity of the switching element.
DISCLOSURE OF THE INVENTION
[0017]
The welding machine of the present invention includes a first rectifying unit that rectifies an AC power input, a first switching element connected between the outputs of the first rectifying unit and a first reverse diode connected in parallel. A first switching circuit configured in series connection with a second switching element in which two reverse diodes are connected in parallel, and a third reverse diode connected in parallel between the outputs of the first rectifying unit A second switching circuit constituted by a series connection of a third switching element connected and a fourth switching element connected in parallel by a fourth reverse diode, and one of the primary side coils is the first switching A transformer connected to the connection between the element and the second switching element, the other end of the primary coil being connected to the connection between the third switching element and the fourth switching element, and 2 of the transformer A second rectifier that rectifies the output from the side coil, an output detector that detects the output of the second rectifier, and an error amplifier that amplifies the error between the output signal from the output detector and the output setting signal A driving circuit that varies a timing at which a control signal is output in accordance with an error amplification signal from an error amplification unit, a first switching element and a second switching element that receive the control signal, A first drive unit that outputs a switching signal that drives the second switching unit; and a second drive unit that outputs a switching signal that inputs the control signal and drives the third switching element and the fourth switching element. The second drive unit is configured to switch the fourth switch at a timing different from the timing at which the first drive unit outputs a switching signal for switching the first switching element from the on state to the off state. And a third timing at a timing different from a timing at which the first drive unit outputs a switching signal for switching the second switching element from the on state to the off state. The switching element is provided with at least one of a configuration for outputting a switching signal for switching the switching element from an on state to an off state.
[0018]
Moreover, the welding machine of this invention is the 1st switching element connected between the 1st rectification part which rectifies | straightens an alternating current power supply input, and the output of a 1st rectification part, and the 1st reverse diode was connected in parallel. And a third switching diode connected between the outputs of the first rectifying unit and a first switching circuit configured in series with a second switching element in which a second switching diode is connected in parallel Is connected in series with a third switching element and a fourth switching element with a fourth reverse diode connected in parallel, and one of the primary side coils is the first switching coil. A transformer connected to the connection between the first switching element and the second switching element, the other end of the primary coil being connected to the connection between the third switching element and the fourth switching element, and a transformer. A second rectifying unit that rectifies the output from the secondary side coil, an output detector that detects the output of the second rectifying unit, and an error between the output signal from the output detector and the output setting signal In a welding machine including an error amplification unit, a control signal is output to the first drive unit, the second drive unit, the third drive unit, and the fourth drive unit in accordance with an error amplification signal from the error amplification unit. The first driving unit outputs a switching signal for driving the first switching element, and the third driving unit performs the second switching at a timing different from that of the first driving unit. The second driving unit is configured to output a switching signal for driving the element, and the second driving unit has a timing different from that at which the first driving unit outputs a switching signal for switching the first switching element from the on state to the off state. First The fourth drive unit outputs a switching signal for switching the second switching element from the on state to the off state, and the fourth driving unit outputs the switching signal for switching the switching element from the on state to the off state. The drive circuit includes at least one of a configuration for outputting a switching signal for switching the third switching element from an on state to an off state at a timing different from the above.
[0019]
Furthermore, the welding machine according to the present invention includes a first switching element connected between a first rectifying unit that rectifies an AC power input and an output of the first rectifying unit, and a first reverse diode connected in parallel. And a third switching diode connected between the outputs of the first rectifying unit and a first switching circuit configured in series with a second switching element in which a second switching diode is connected in parallel Is connected in series with a third switching element and a fourth switching element with a fourth reverse diode connected in parallel, and one of the primary side coils is the first switching coil. A transformer connected to the connection between the switching element and the second switching element and the other side of the primary coil connected to the connection between the third switching element and the fourth switching element; A second rectifier that rectifies the output from the secondary coil of the power supply, an output detector that detects the output of the second rectifier, and an error between the output signal from the output detector and the output setting signal A welding circuit including an error amplification unit that includes a drive circuit that varies a timing at which a control signal is output to the fifth drive unit and the sixth drive unit according to an error amplification signal from the error amplification unit; The driving unit 5 outputs switching signals for driving the first switching element and the fourth switching element, respectively, and the sixth driving unit outputs the second signal at a timing different from the timing of the fifth driving unit. A switching signal for driving the switching element and the third switching element is output, and the switching signal for switching the first switching element from the on state to the off state is output. The fifth drive unit outputs a switching signal for switching the fourth switching element from the on state to the off state at a timing different from the timing, and outputs a switching signal for switching the second switching element from the on state to the off state And a configuration in which the sixth drive unit outputs a switching signal for switching the third switching element from the on state to the off state at a timing different from the timing at which the third driving element is turned on. .
【The invention's effect】
[0020]
The present invention suppresses the heat generation of the power semiconductor by suppressing the current to the reverse diode, and improves the reliability by suppressing the surge voltage applied to the switching element by regenerating the counter electromotive voltage generated in the transformer 10. A high welding machine can be realized, and the present invention is industrially useful as a device used in the welding industry and the industrial field in which a relatively large current output is handled and output is controlled.
BEST MODE FOR CARRYING OUT THE INVENTION
[0021]
(Embodiment 1)
FIG. 1 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 1 of the present invention. In FIG. 1, a first switching circuit 31 and a second switching circuit 32 are connected in parallel between output terminals of a first rectifying unit 1 that rectifies a three-phase or single-phase AC input. The first switching circuit 31 is configured by connecting the first switching element 2 and the second switching element 4 in series. A connection point between the first switching element 2 and the second switching element 4 is a circuit output terminal 33 of the first switching circuit 31. In addition, a first reverse diode 3 and a second reverse diode 5 are connected in parallel to the first switching element 2 and the second switching element 4, respectively. The second switching circuit 32 is configured by connecting the third switching element 6 and the fourth switching element 8 in series. The connection point is the circuit output terminal 34 of the second switching circuit 32. In addition, a third reverse diode 7 and a fourth reverse diode 9 are connected in parallel to the third switching element 6 and the fourth switching element 8, respectively. The primary coil of the power conversion transformer 10 is connected between the circuit output terminals 33 and 34. A primary current flows through the primary coil of the transformer 10 in the first direction via the first switching element 2 and the fourth switching element 8, and the second switching element 4 and the fourth switching element 8. And a primary current flows in a second direction opposite to the first direction.
[0022]
The secondary coil of the transformer 10 is connected to a second rectifying unit 11 that rectifies the output. The output of the 2nd rectification | straightening part 11 is connected to the output terminals 13 and 14 of a welding machine. The current rectified by the second rectifying unit 11 is supplied to the arc load unit through the output terminals 13 and 14. In FIG. 1, one of the outputs of the second rectifying unit 11 is connected to the output terminal 14 via the output current detector 12.
[0023]
The output current flowing to the load unit is detected by the output current detector 12, and an output signal proportional to the output current is input from the output current detector 12 to the error amplifying unit 15. The error amplifier 15 receives the output signal of the output current detector 12, compares the error with the output setting signal Vr, and outputs an amplified error amplified signal Ve. The drive circuit 16 receives the error amplification signal Ve and outputs control signals S1 and S2 that change the operation timing according to the error amplification signal Ve to the first drive unit 17 and the second drive unit 18, respectively. In response to the output signal from the drive circuit 16, the first drive unit 17 outputs a switching signal for controlling on / off of the first switching element 2 and the second switching element 4 at different timings. The drive unit 18 outputs a switching signal for performing on / off control of the third switching element 6 and the fourth switching element 8 at different timings. As described above, the welding machine that performs constant current control according to Embodiment 1 of the present invention is configured.
[0024]
The operation of the welding machine configured as described above will be described.
[0025]
FIG. 9 is a timing chart showing the operating states of the first to fourth switching elements 2, 4, 6, 8 and the primary current waveform of the transformer 10. As shown in FIG. 9, in order to reduce the output current value, the on-times of the first to fourth switching elements 2, 4, 6, 8 are shortened, and in order to increase the output current value, The drive circuit 16 outputs control signals S1 and S2 so as to increase the time. The first driving unit 17 outputs a switching signal at different timings to the first switching element 2 and the second switching element 4 in accordance with the control signal S1. And the 2nd drive part 18 outputs a switching signal with a different timing with respect to the 3rd switching element 6 and the 4th switching element 8 according to control signal S2. At this time, the first switching element 2 and the fourth switching element 8 are simultaneously turned on. Further, the first driving is performed so that the second switching element 4 and the third switching element 6 are simultaneously turned on at a timing different from the period during which the first switching element 2 and the fourth switching element 8 are turned on. The unit 17 and the second driving unit 18 output a switching signal.
[0026]
Further, after the first switching element 2 is switched to the off state, the fourth switching element is delayed by a predetermined time until the switching surge current generated by the first switching element 2 being turned off disappears. 8 switches to the off state. In addition, after the second switching element 4 is switched to the OFF state, the third switching is delayed by a predetermined time until the switching surge current generated when the second switching element 4 is turned OFF disappears. Element 6 switches to the off state. The 1st drive part 17 and the 2nd drive part 18 output a switching signal so that it may become such a sequence. In this way, the timing for switching the fourth switching element 8 to the OFF state is delayed until the switching surge current of the first switching element 2 disappears. Thereby, after the first switching element 2 is switched to the OFF state, a change occurs in the current flowing in the primary side coil of the transformer 10 in the first direction, and the back electromotive voltage generated in the transformer 10 starts to decrease. It is regenerated within. This is because a current path through which the switching surge current flows in the first direction in the primary coil of the transformer 10 through the fourth switching element 8 and the second reverse diode 5 is formed. Further, when the fourth switching element 8 is switched to the OFF state, the surge voltage is suppressed because the switching surge current flowing in the primary side coil of the transformer 10 has almost disappeared. Further, since the regenerative time in the bridge, that is, the predetermined time until the switching surge current of the first switching element 2 disappears (for example, several tens of nanoseconds to several hundreds of nanoseconds) is short, the current flows through the second reverse diode 5. Since the current has a minute value, heat generation of the power semiconductor (including the second switching element 4 and the second reverse diode 5) is suppressed.
[0027]
Similarly, the timing for switching the third switching element 6 to the OFF state is delayed until the switching surge current of the second switching element 4 disappears. As a result, after the second switching element 4 is switched to the OFF state, a change occurs in the current flowing through the primary coil of the transformer 10 in the second direction, and the back electromotive voltage generated in the transformer 10 starts to decrease, It is regenerated within. This is because the current path through which the switching surge current flows in the second direction in the primary coil of the transformer 10 through the first reverse diode 3 and the third switching element 6 is formed. When the third switching element 6 is switched to the OFF state, the surge voltage is suppressed because the switching surge current flowing in the primary coil of the transformer 10 has almost disappeared. In addition, since the regenerative time in the bridge, that is, the predetermined time (several tens of nanoseconds to several hundreds of nanoseconds) until the switching surge current of the second switching element 4 disappears is short, Since it becomes minute, heat generation of the power semiconductor (including the first switching element 2 and the first reverse diode 3) is suppressed.
[0028]
As described above, according to the welding machine of the present embodiment, the on / off state switching timing of each switching element is performed at the same time as the on state, and the timing of switching to the off state is delayed. . With this configuration, it is possible to suppress the current to the reverse diodes 3 and 5. For this reason, it is possible to suppress the heat generation of the power semiconductor including the reverse diodes 3 and 5, regenerate the counter electromotive voltage generated in the transformer 10, and suppress the surge voltage applied to the switching elements 6 and 8. .
[0029]
When the switching element is suddenly switched to the OFF state in a state where a high current value is flowing through the switching element, the current rapidly decreases and a surge voltage is generated due to an inductance component of the circuit. A surge voltage is also generated by a counter electromotive voltage generated in the transformer 10.
[0030]
In addition, although the welding machine which performs constant current control was described here, when performing constant voltage control, it replaces with the output current detector 12 as an output detector, and detects the voltage between the output terminals 13 and 14. An output voltage detector is provided. The output signal from the output voltage detector is input to the error amplifying unit 15. The error amplification unit 15 may be configured to output the error amplification signal Ve by comparing the output setting signal Vr with the output signal from the output voltage detector.
[0031]
In FIG. 9, the timing relationship for switching the first switching element 2 and the fourth switching element 8 to the OFF state may be opposite to that described above. That is, after the fourth switching element 8 is switched to the OFF state, the first switching element 2 may be switched to the OFF state after the back electromotive voltage generated in the transformer 10 is regenerated in the bridge. Similarly, the timing relationship for switching the second switching element 4 and the third switching element 6 to the OFF state may be opposite to the above. Furthermore, the timing relationship for switching the first switching element 2 and the fourth switching element 8 to the OFF state is different from the timing relationship for switching the second switching element 4 and the third switching element 6 to the OFF state. Needless to say.
[0032]
Examples of power semiconductors including switching elements and reverse diodes include IGBTs (insulated gate bipolar transistors), MOSFETs (oxide semiconductor field effect transistors), and IPMs (intelligent power modules). In the IGBT or MOSFET, the first switching element 2 and the first reverse diode 3, the second switching element 4 and the second reverse diode 5, the third switching element 6 and the third reverse diode 7, and the fourth With the combination of the switching element 8 and the fourth reverse diode 9, each switching element and the reverse diode connected in parallel with each other are configured in one IGBT package. For this reason, when IGBT is used, it is not necessary to add the reverse diode connected in parallel with the switching element. The same applies to MOSFETs. However, some MOSFETs do not include a reverse diode. In this case, it is necessary to add a reverse diode to the outside. In the IPM, the first to fourth switching elements 2, 4, 6, 8 and the first to fourth reverse diodes 3, 5, 7, 9 are formed in one IPM package. For this reason, when IPM is used, it is not necessary to add an external reverse diode connected in parallel to the switching element.
[0033]
With such a configuration, the heat generation of the power semiconductor is suppressed by suppressing the current to the reverse diode, and the surge voltage applied to the switching element is suppressed by regenerating the counter electromotive voltage generated in the transformer 10. A high-performance welder can be realized.
[0034]
In the first embodiment, regarding the timing of switching each switching element from the on state to the off state, the difference in timing relationship between the first switching element and the fourth switching element, or the second switching element and the second switching element. Only one of the differences in timing relationship with the three switching elements may be used. In that case, the same effect can be obtained for the switching element having a different timing relationship.
[0035]
(Embodiment 2)
FIG. 2 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 2 of the present invention. In the second embodiment, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted. 2 is different from the first embodiment in that a first delay circuit 19 is provided in the second drive unit 218. FIG.
[0036]
In the welding machine shown in FIG. 2, in the configuration in which the control signal S1 from the drive circuit 16 to the first drive unit 17 and the control signal S2 to the second drive unit 218 are output at the same timing, The first delay circuit 19 delays the timing of outputting the switching signal for switching the fourth switching element 8 to the OFF state until a predetermined time when the switching surge current generated in the first switching element 2 disappears, and the third delay circuit 19 The timing for outputting the switching signal for switching the switching element 6 to the OFF state can be delayed until a predetermined time when the switching surge current generated in the second switching element 4 disappears.
[0037]
The configuration of the first delay circuit 19 includes a configuration in which the delay time is changed by a timer using an integrated circuit, and a delay time in which the charge / discharge time is changed by changing the constants of resistors and capacitors using a time constant circuit. The structure etc. which change can be used.
[0038]
In the second embodiment, the fourth switching element is delayed with respect to the first switching element and the third switching element is set to the second timing with respect to the timing of switching each switching element from the on state to the off state. The example which delays with respect to a switching element was shown. However, the present invention is not limited to this, and the timing may be delayed only by either the fourth switching element or the third switching element, and the same effect can be obtained for the switching element whose timing is delayed. .
[0039]
With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.
[0040]
(Embodiment 3)
FIG. 3 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 3 of the present invention. In the third embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 3, the difference from the first embodiment is that a logic integrated circuit 20 is configured in the drive circuit 216.
[0041]
In FIG. 3, a program for outputting a drive signal S1 to the first drive unit 17 and a drive signal S2 to the second drive unit 18 is stored in the logic integrated circuit 20 of the drive circuit 216. ing. Thus, the output timing of the control signal S2 for switching the fourth switching element 8 to the OFF state is delayed until a predetermined time when the switching surge current generated in the first switching element 2 disappears, and the third switching element 6 The output timing of the control signal S2 for switching to the OFF state can be delayed until a predetermined time when the switching surge generated in the second switching element 4 disappears.
[0042]
Note that the logic integrated circuit 20 is one that rewrites internal logic such as a CPU (Central Processing Unit), PLD (Programmable Logic Device), FPGA (Field Programmable Gate Array), DSP (Digital Signal Processor), and the like.
[0043]
With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.
[0044]
(Embodiment 4)
FIG. 4 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 4 of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 4, the difference from the first embodiment is that the drive circuit 316 outputs four signals S3, S4, S5, and S6, which are respectively output to the first drive unit 17, the second drive unit 18, and the third drive unit 316. The signals are input to the drive unit 21 and the fourth drive unit 22. Then, the outputs of the first drive unit 17, the second drive unit 18, the third drive unit 21, and the fourth drive unit 22 are converted into the first switching element 2, the fourth switching element 8, and the second output, respectively. The switching element 4 and the third switching element 6 are input. Thus, the first drive unit 17 provides the first switching element 2, the second drive unit 18 provides the fourth switching element 8, the third drive unit 21 provides the second switching element 4, The fourth drive unit 22 controls the third switching element 6. The difference from the first embodiment is that a driving unit is provided for each switching element, and the switching elements can be independently controlled.
[0045]
In FIG. 4, the control signal S3 for turning on the first and fourth switching elements from the drive circuit 316 to the first drive unit 17 and the second drive unit 18 at the same timing, respectively. Send S4. Then, when the ON period has passed, the drive circuit 316 sends a control signal S3 for turning off the first switching element 2 to the first drive unit 17. Thereafter, a control signal for turning off the fourth switching element 8 with respect to the second drive unit 18 at a timing delayed until a predetermined time when the switching surge current generated in the first switching element 2 disappears. Send S4. Similarly, control signals S5 and S6 for turning on the second and third switching elements are respectively sent from the drive circuit 316 to the third drive unit 21 and the fourth drive unit 22 at the same timing. . Then, when the ON period has passed, the drive circuit 316 sends a control signal S5 for turning off the second switching element 4 to the third drive unit 21. Thereafter, a control signal for turning off the third switching element 6 with respect to the fourth drive unit 22 at a timing delayed until a predetermined time when the switching surge current generated in the second switching element 4 disappears. Send S6.
[0046]
With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.
[0047]
In the fourth embodiment, regarding the timing of switching each switching element from the on state to the off state, the difference in timing relationship between the first switching element and the fourth switching element, or the second switching element and the second switching element. Only one of the differences in timing relationship with the three switching elements may be used. In that case, the same effect can be obtained for the switching element having a different timing relationship.
[0048]
(Embodiment 5)
FIG. 5 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 5 of the present invention. In the present embodiment, the same components as those in the fourth embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 5, the difference from the fourth embodiment is that the first delay circuit 19 is configured inside the second drive unit 218 and the second delay circuit 23 is configured inside the fourth drive unit 222. Is a point.
[0049]
In the welding machine shown in FIG. 5, the control signal S3 from the drive circuit 316 to the first drive unit 17 and the control signal S4 to the second drive unit 218 are output at the same timing, and the third The control signal S5 to the drive unit 21 and the control signal S6 to the fourth drive unit 222 are output at the same timing. At this time, the first switching element 2 generates a timing for outputting a switching signal for switching the fourth switching element 8 from the on state to the off state by the first delay circuit 19 and the second delay circuit 23. Delay until a predetermined time until the switching surge current disappears. At the same time, the timing for outputting the switching signal for switching the third switching element 6 from the on state to the off state is delayed until a predetermined time when the switching surge current generated in the second switching element 4 disappears.
[0050]
Note that the delay circuits 19 and 23 are configured by using an integrated circuit to form a timer and changing the delay time, or by changing the constants using a time constant circuit composed of a resistor and a capacitor, thereby reducing the charge / discharge time. There are means for changing the delay time by changing.
[0051]
With such a configuration, similarly to the fourth embodiment, it is possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.
[0052]
(Embodiment 6)
FIG. 6 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 6 of the present invention. In the present embodiment, the same components as those in the fourth embodiment are denoted by the same reference numerals and detailed description thereof is omitted. 6 differs from the fourth embodiment in that a logic integrated circuit 20 is configured in the drive circuit 216. FIG.
[0053]
In FIG. 6, the control signal S3 from the drive circuit 216 to the first drive unit 17, the control signal S4 to the second drive unit 18, the control signal S5 to the third drive unit 21, and the fourth The control signal S6 to the drive unit 22 is controlled by a program stored in the logic integrated circuit 20. Accordingly, the timing at which the second drive unit 18 outputs the switching signal for switching the fourth switching element 8 from the on state to the off state is set to a predetermined time when the switching surge current generated in the first switching element 2 disappears. Delay. At the same time, the timing at which the fourth drive unit 22 outputs the switching signal for switching the third switching element 6 from the on state to the off state is delayed until a predetermined time at which the switching surge current generated in the second switching element 4 disappears. .
[0054]
With such a configuration, the heat generation of the power semiconductor is suppressed by suppressing the current to the reverse diode, and the surge voltage applied to the switching element is suppressed by regenerating the counter electromotive voltage generated in the transformer 10. A high-performance welder can be realized.
[0055]
As the logic integrated circuit 20, a circuit, such as a CPU, PLD, FPGA, DSP, which rewrites the internal theory is used.
[0056]
(Embodiment 7)
FIG. 7 is a block diagram showing a circuit configuration of a welding machine according to Embodiment 7 of the present invention. In the present embodiment, the same components as those in the first embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 7, the fifth driving unit 24 outputs a switching signal to the first switching element 2 and the fourth switching element 8, and the sixth driving unit 25 is different from the first embodiment in that the fifth driving unit 24 outputs the switching signal. The switching signal is output to the switching element 4 and the third switching element 6.
[0057]
At this time, the first switching element 2 and the fourth switching element 8 are simultaneously switched on, and the second switching element 4 and the third switching element 6 are simultaneously turned on at a timing different from this timing. Switching signals are output from the fifth driving unit 24 and the sixth driving unit 25 so as to switch to the state. After a predetermined on period, the fifth drive unit 24 outputs a switching signal for switching the first switching element 2 to the off state. Then, after delaying until a predetermined time when the switching surge current generated in the first switching element 2 disappears, a switching signal for switching the fourth switching element 8 to the OFF state is output from the fifth drive unit 24. On the other hand, after a predetermined on period, the sixth drive unit 25 outputs a switching signal for switching the second switching element 4 to the off state. Then, after delaying until a predetermined time when the switching surge current generated in the second switching element 4 disappears, a switching signal for switching the third switching element 6 to the OFF state is output from the sixth drive unit 25.
[0058]
With such a configuration, similarly to the first embodiment, it becomes possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.
[0059]
In the seventh embodiment, regarding the timing of switching each switching element from the on state to the off state, the difference in timing relationship between the first switching element and the fourth switching element, or the second switching element and the second switching element. Only one of the differences in timing relationship with the three switching elements may be used. In that case, the same effect can be obtained for the switching element having a different timing relationship.
[0060]
(Embodiment 8)
FIG. 8 is a block diagram showing a circuit configuration of the welding machine according to the eighth embodiment of the present invention. In the present embodiment, the same components as those in the seventh embodiment are denoted by the same reference numerals and detailed description thereof is omitted. In FIG. 8, the difference from the seventh embodiment is that the first delay circuit 19 is configured in the fifth drive unit 224. The second delay circuit 23 is configured inside the sixth drive unit 225.
[0061]
In the welding machine shown in FIG. 8, the control signal S <b> 1 output from the drive circuit 16 is input to the fifth drive unit 224. The timing at which the fifth driving unit 224 outputs the switching signal for switching the fourth switching element 8 to the OFF state after outputting the switching signal for switching the first switching element 2 to the OFF state is set to the first switching element. 2 can be delayed by the first delay circuit 19 until the switching surge current generated in 2 disappears.
[0062]
Similarly, the control signal S <b> 2 from the drive circuit 16 is input to the sixth drive unit 225. The timing at which the sixth drive unit 225 outputs the switching signal for switching the third switching element 6 to the OFF state after outputting the switching signal for switching the second switching element 4 to the OFF state is set to the second switching element. 4 can be delayed by the second delay circuit 23 until the switching surge current generated in 4 disappears.
[0063]
Note that the delay circuits 19 and 23 are configured by using an integrated circuit to form a timer and changing the delay time, or by changing the constants using a time constant circuit composed of a resistor and a capacitor, thereby reducing the charge / discharge time. There are means for changing the delay time by changing.
[0064]
With this configuration, as in the seventh embodiment, it is possible to suppress the current to the reverse diode, suppress the heat generation of the power semiconductor, and regenerate the counter electromotive voltage generated in the transformer 10 to the switching element. A highly reliable welder can be realized by suppressing the applied surge voltage.
[Industrial applicability]
[0065]
The present invention suppresses the heat generation of the power semiconductor by suppressing the current to the reverse diode, and improves the reliability by suppressing the surge voltage applied to the switching element by regenerating the counter electromotive voltage generated in the transformer 10. A high welding machine can be realized, and the present invention is industrially useful as a device used in the welding industry and the industrial field in which a relatively large current output is handled and output is controlled.
[Brief description of the drawings]
[0066]
FIG. 1 is a block diagram showing a circuit configuration of a welding machine according to a first embodiment of the present invention.
FIG. 2 is a block diagram showing a circuit configuration of a welding machine according to a second embodiment of the present invention.
FIG. 3 is a block diagram showing a circuit configuration of a welding machine according to a third embodiment of the present invention.
FIG. 4 is a block diagram showing a circuit configuration of a welding machine according to a fourth embodiment of the present invention.
FIG. 5 is a block diagram showing a circuit configuration of a welding machine according to a fifth embodiment of the present invention.
FIG. 6 is a block diagram showing a circuit configuration of a welding machine according to a sixth embodiment of the present invention.
FIG. 7 is a block diagram showing a circuit configuration of a welding machine according to a seventh embodiment of the present invention.
FIG. 8 is a block diagram showing a circuit configuration of a welding machine according to an eighth embodiment of the present invention.
FIG. 9 is a timing chart showing the inverter operation of the welding machine of the present invention.
FIG. 10 is a block diagram showing a circuit configuration of a conventional welder
FIG. 11 is a timing chart showing inverter operation by partial resonance control of a conventional welder.
FIG. 12 is a timing chart showing inverter operation by PWM control of a conventional welder
[Explanation of symbols]
[0067]
1,101 first rectification unit
2,102 first switching element
3,103 first reverse diode
4,104 Second switching element
5,105 second reverse diode
6,106 third switching element
7,107 Third reverse diode
8,108 Fourth switching element
9,109 Fourth reverse diode
10,110 transformer
11, 111 Second rectification unit
12,112 Output current detector
13, 14, 113, 114 Output terminal
15,115 Error amplifier
16, 116, 216, 316 drive circuit
17,117 First drive unit
18, 118, 218 Second drive unit
19 First delay circuit
20 logic integrated circuits
21 3rd drive part
22, 222 Fourth drive unit
23 Second delay circuit
24,224 fifth drive section
25, 225 sixth drive unit
31, 131 First switching circuit
32,132 second switching circuit
33, 34, 133, 134 Circuit output terminal
Vr output setting signal
Ve Error amplification signal
S1, S2, S3, S4, S5, S6 control signal

Claims (11)

A first switching element rectifying an AC power supply input and a first switching element connected in parallel with a first reverse diode connected between the outputs of the first rectifier and a second reverse diode are connected in parallel. A third switching diode connected in parallel with a first switching circuit configured in series with a connected second switching element, and a third reverse diode connected between the outputs of the first rectifying unit. And a fourth switching element in which a fourth reverse diode is connected in parallel, and one of the primary coils is connected to the first switching element and the first switching element. A transformer connected to a connection part between the second switching element and the other end of the primary coil connected to a connection part between the third switching element and the fourth switching element; A second rectifier that rectifies the output from the secondary coil of the power source, an output detector that detects the output of the second rectifier, and an error between the output signal from the output detector and the output setting signal In a welding machine equipped with an error amplification unit that amplifies
A driving circuit that varies a timing at which a control signal is output in accordance with an error amplification signal from the error amplifying unit; and a switching circuit that drives the first switching element and the second switching element by inputting the control signal. A first driving unit that outputs a signal; and a second driving unit that outputs the switching signal that inputs the control signal and drives the third switching element and the fourth switching element.
The second driving unit switches the fourth switching element from the on state at a timing different from the timing at which the first driving unit outputs a switching signal for switching the first switching element from the on state to the off state. A configuration for outputting a switching signal for switching to an off state;
A switching signal for switching the third switching element from the on state to the off state is output at a timing different from a timing at which the first driving unit outputs a switching signal for switching the second switching element from the on state to the off state. A welding machine comprising at least one of the configurations to be configured. A switching surge that flows through the fourth switching element that occurs after the first switching element switches from the on state to the off state, at a timing for outputting a switching signal that switches the fourth switching element from the on state to the off state. A configuration that delays until a predetermined time when the current disappears;
A switching surge that flows through the third switching element that occurs after the second switching element is switched from the on state to the off state, at a timing for outputting a switching signal for switching the third switching element from the on state to the off state. With a configuration that delays until a predetermined time when the current disappears,
The welding machine according to claim 1, wherein the second drive unit has at least one of the configurations. The second drive unit changes the fourth switching element from the on state to the off state with respect to the timing at which the first drive unit outputs a switching signal for switching the first switching element from the on state to the off state. Delaying the timing of outputting the switching signal to be switched;
The second drive unit changes the third switching element from the on state to the off state with respect to the timing at which the first drive unit outputs a switching signal for switching the second switching element from the on state to the off state. Delaying the timing of outputting the switching signal to be switched,
The welding machine according to claim 1, wherein the second driving unit includes a delay circuit that performs at least one of the delay circuits. The switching signal for switching the fourth switching element from the on state to the off state with respect to the timing at which the first drive unit outputs the switching signal for switching the first switching element from the on state to the off state. Delaying the output timing of the two drive units;
The switching signal for switching the third switching element from the on state to the off state with respect to the timing at which the first drive unit outputs the switching signal for switching the second switching element from the on state to the off state. Delaying the output timing of the two drive units,
The welding machine according to claim 1, wherein the driving circuit includes a logic integrated circuit that stores a program for controlling to perform at least one of the operations. A first switching element rectifying an AC power supply input and a first switching element connected in parallel with a first reverse diode connected between the outputs of the first rectifier and a second reverse diode are connected in parallel. A third switching diode connected in parallel with a first switching circuit configured in series with a connected second switching element, and a third reverse diode connected between the outputs of the first rectifying unit. And a fourth switching element in which a fourth reverse diode is connected in parallel, and one of the primary coils is connected to the first switching element and the first switching element. A transformer connected to a connection part between the second switching element and the other end of the primary coil connected to a connection part between the third switching element and the fourth switching element; A second rectifier that rectifies the output from the secondary coil of the power source, an output detector that detects the output of the second rectifier, and an error between the output signal from the output detector and the output setting signal In a welding machine equipped with an error amplification unit that amplifies
A drive circuit that varies a timing of outputting a control signal to the first drive unit, the second drive unit, the third drive unit, and the fourth drive unit according to an error amplification signal from the error amplification unit;
The first driving unit outputs a switching signal for driving the first switching element, and the third driving unit is configured to drive the second switching element at a timing different from that of the first driving unit. A configuration for outputting a signal,
The second driving unit switches the fourth switching element from the on state at a timing different from the time when the first driving unit outputs a switching signal for switching the first switching element from the on state to the off state. A configuration for outputting a switching signal for switching to an off state;
The fourth driving unit switches the third switching element from the on state at a timing different from the time when the third driving unit outputs a switching signal for switching the second switching element from the on state to the off state. With a configuration that outputs a switching signal to switch to the off state,
A welding machine, wherein the drive circuit has at least one of the configurations. The fourth switching element is turned on after the switching surge current flowing through the fourth switching element generated when the first switching element is changed from the on state to the off state is delayed until a predetermined time is extinguished. A configuration in which the second drive unit outputs a switching signal for switching from an off state to an off state;
The third switching element is turned on after the switching surge current flowing through the third switching element generated when the second switching element is changed from the on state to the off state is delayed until a predetermined time is extinguished. A configuration in which the fourth drive unit outputs a switching signal for switching from an off state to an off state,
The welding machine according to claim 5, wherein the drive circuit has at least one of the configurations. Timing for outputting a switching signal for switching the fourth switching element from the on state to the off state with respect to timing for the first driving unit to output a switching signal for switching the first switching element from the on state to the off state. A configuration in which the second driving unit includes a first delay circuit for delaying
Timing for outputting a switching signal for switching the third switching element from the on state to the off state with respect to timing for the third driving unit to output a switching signal for switching the second switching element from the on state to the off state. A configuration in which the fourth drive unit includes a second delay circuit for delaying
The welding machine according to claim 5, comprising at least one of the configurations. The switching signal for switching the fourth switching element from the on state to the off state with respect to the timing at which the first drive unit outputs the switching signal for switching the first switching element from the on state to the off state. Delaying the output timing of the drive unit,
A switching signal for switching the third switching element from the on state to the off state at a timing at which the third drive unit outputs a switching signal for switching the second switching element from the on state to the off state. Delaying the output timing of the drive unit
The welding machine according to any one of claims 5 and 6, wherein the drive circuit includes a logic integrated circuit storing a program for controlling to perform at least one of them. A first switching element rectifying an AC power supply input and a first switching element connected in parallel with a first reverse diode connected between the outputs of the first rectifier and a second reverse diode are connected in parallel. A third switching circuit connected in parallel with a first switching circuit configured in series with a connected second switching element, and a third reverse diode connected between the outputs of the first rectifying unit. And a fourth switching element in which a fourth reverse diode is connected in parallel, and one of the primary coils is connected to the first switching element and the first switching element. A transformer connected to a connection part between the second switching element and the other end of the primary coil connected to a connection part between the third switching element and the fourth switching element; A second rectifier that rectifies the output from the secondary coil of the power source, an output detector that detects the output of the second rectifier, and an error between the output signal from the output detector and the output setting signal In a welding machine equipped with an error amplification unit that amplifies
A drive circuit that varies a timing of outputting a control signal to the fifth drive unit and the sixth drive unit in accordance with an error amplification signal from the error amplification unit;
The fifth driving unit outputs switching signals for driving the first switching element and the fourth switching element, respectively, and the sixth driving unit is a timing of the fifth driving unit. It is configured to output switching signals for driving the second switching element and the third switching element at different timings, respectively.
The fifth drive unit outputs a switching signal for switching the fourth switching element from the on state to the off state at a timing different from the timing for outputting the switching signal for switching the first switching element from the on state to the off state. Configuration to
The sixth drive unit outputs a switching signal for switching the third switching element from the on state to the off state at a timing different from the timing for outputting the switching signal for switching the second switching element from the on state to the off state. With the configuration to
A welding machine comprising at least one of the configurations. The fifth driving unit generates a timing for outputting a switching signal for switching the fourth switching element from the on state to the off state when the first switching element is changed from the on state to the off state. A configuration in which the switching surge current flowing through the switching element 4 is delayed until a predetermined time when the switching surge current disappears;
The sixth driving unit generates a timing for outputting a switching signal for switching the third switching element from an on state to an off state when the second switching element is changed from an on state to an off state. And a configuration in which the switching surge current flowing through the switching element 3 is delayed until a predetermined time is extinguished.
The welding machine according to claim 9, comprising at least one of the configurations. The fifth driving unit outputs a switching signal for switching the fourth switching element from the on state to the off state with respect to a timing for outputting the switching signal for switching the first switching element from the on state to the off state. A first delay circuit that internally delays
The sixth drive unit outputs a switching signal for switching the third switching element from the on state to the off state with respect to a timing for outputting the switching signal for switching the second switching element from the on state to the off state. With a second delay circuit for delaying
The welding machine according to claim 9, comprising at least one of the configurations.

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