JP2005103569A - Power unit for ac arc welding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve conventional problems in a power unit for AC arc welding, namely, problems in which use of a large capacity switching element is required because only one pair of the oppositely facing two pairs of switching elements of a secondary inverter circuit is used at the time of DC mode, and in which a large switching loss is generated in the polarity inversion of the secondary side inverter circuit at the time of AC mode. <P>SOLUTION: The power unit for AC arc welding is equipped with an inverter circuit for converting to high frequency AC voltage, a main control circuit for controlling the output of the inverter circuit, and a main transformer for converting to a voltage suitable for arc welding. Further, with the emitter side of a first switching element connected to the first terminal of the main transformer, while the collector side connected to the collector side of a second switching element; with the collector side of a third switching element connected to the second terminal of the main transformer, while the emitter side connected to the emitter side of a fourth switching element; and with the first to the fourth reverse conducting diodes parallelly connected to each switching element with the reverse polarity; the power unit is also equipped with a secondary inverter control circuit, conducting the second and the third switching element at the time of EN polarity, and conducting the first and the fourth switching element at the time of EP polarity. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to the configuration and control of an inverter circuit on a secondary side in a power supply device for AC arc machining.

  Conventionally, as shown in FIG. 15, the primary rectifier circuit DR1 rectifies the output of the three-phase AC commercial power supply AC and converts it into a DC voltage, and the bridge-connected primary inverter circuit includes fifth switching elements TR5 to TR5. A fifth switching element TR5 and an eighth switching element TR8 that are formed by the eighth switching element TR8 and form opposite sides, and a sixth switching element TR6 and a seventh switching element TR7 form a pair. The first element driving signal Sc1 to the fourth element driving signal Sc4 output from the main control circuit SC convert the DC voltage into a high-frequency AC voltage by repeating conduction and interruption of these two elements. Further, the main transformer INT converts the high-frequency AC voltage on the primary side into a voltage suitable for arc machining.

  The secondary rectifier circuit DR2 rectifies the output of the main transformer INT and converts it into a DC voltage, and the bridge-connected secondary inverter circuit is formed by the ninth switching element TR9 to the twelfth switching element TR12, The ninth switching element TR9 and the twelfth switching element TR12 that form opposite sides and the tenth switching element TR10 and the eleventh switching element TR11 form a pair and output from the secondary inverter drive circuit KD. The first element drive signal Kd1 for the secondary inverter to the fourth element drive signal Kd4 for the secondary inverter, the two elements forming the pair repeat conduction and interruption, and the DC voltage is changed to an AC voltage at a predetermined low frequency. Convert to

  The main control circuit SC sets the direct current mode or the alternating current mode and inputs it to the secondary inverter drive circuit KD. The polarity switching circuit TM sets the polarity switching frequency and the polarity ratio of the secondary inverter circuit to predetermined values and outputs them as a polarity switching signal Tm.

  When the main control circuit SC sets the DC mode, the secondary inverter drive circuit KD always conducts the ninth switching element TR9 and the twelfth switching element TR12, and the tenth switching element TR10 and the eleventh switching element. Since the element TR11 is always cut off, only one of the paired switching elements has a heavy load, and a large capacity switching element is required.

JP-A-4-279279

  In a conventional AC arc machining power supply device, a switching element having a large capacity must be used in order to use only one pair of two opposing switching elements of the secondary inverter circuit in the DC mode. In the AC mode, a large switching loss occurs when the polarity of the secondary inverter circuit is switched.

  In order to solve the above-described problems, the first invention is a DC power supply circuit that outputs a DC voltage, an inverter circuit that converts the output of the DC power supply circuit into a high-frequency AC voltage, and a main control that controls the inverter circuit. A main control circuit for outputting a signal; a main transformer for converting the high-frequency AC voltage into a voltage suitable for arc machining and outputting the converted voltage to a first terminal and a second terminal provided on the secondary side; and The first switching element connecting the emitter side of the first switching element to the first terminal of the main transformer, and the first switching element connecting the collector side of the second switching element to the collector side of the first switching element. 2 switching elements, the third switching element connecting the collector side of the third switching element to the second terminal of the main transformer, and the fourth switching element The fourth switching element connecting the emitter side to the emitter side of the third switching element, the first reverse conducting diode connected in parallel to the first switching element in reverse polarity, and the reverse polarity in the second switching element A second reverse conducting diode connected in parallel to the third switching element, a third reverse conducting diode connected in parallel to the third switching element in reverse polarity, and a fourth reverse conducting diode connected in parallel to the fourth switching element in reverse polarity A workpiece to be connected to a connection point between the emitter side of the second switching element and the collector side of the fourth switching element, an electrode connected to the intermediate terminal on the secondary side of the main transformer, and the electrode A polarity switching circuit that outputs a polarity switching signal for switching between a negative EN polarity and the electrode plus EP polarity, and the electrode is made negative in response to the polarity switching signal. A secondary inverter control circuit for conducting the first switching element and the fourth switching element when the polarity is EP, in which the second switching element and the third switching element are turned on when the polarity is EN, and the electrode is positive; When the electrode has a negative EN polarity and the output voltage of the first terminal of the main transformer is a positive potential, a current is passed through the path of the electrode, the first reverse conducting diode, the second switching element, and the workpiece. When the output voltage of the second terminal of the main transformer is a negative potential, current is passed through the electrode, the third switching element, the fourth reverse conducting diode, and the path of the workpiece, and the electrode is positive. When the output voltage of the first terminal of the main transformer is a positive potential with the EP polarity of the above, the current is passed through the path of the work piece, the fourth switching element, the third reverse conducting diode, and the electrode. A power supply device for AC arc machining, wherein a current is passed through a workpiece, a second reverse conducting diode, a first switching element, and an electrode path when the output voltage of the second terminal of the pressure device is a negative potential It is.

  According to a second aspect of the present invention, a polarity switching synchronization circuit is provided between the polarity switching circuit and the secondary inverter control circuit, and the polarity switching synchronization circuit receives the polarity switching signal and the main control signal and receives the polarity. At the time of EN / EP polarity switching in which the switching signal is synchronized with the main control signal and the electrode switches from minus to plus, the first switching element is conducted at zero voltage during the first conduction period of the main control signal. The third switching element is cut off at zero current, the second switching element is cut off at zero voltage and the fourth switching element is turned on at zero current during the second conduction period, and the electrode is changed from positive to negative. When switching the polarity of EP / ENP, the first switching element is cut off at zero current and the third switching element is turned on at zero voltage during the first conduction period of the main control signal. 2. The AC arc machining power supply device according to claim 1, wherein during the conduction period, the polarity switching synchronization signal for conducting the second switching element at zero current and shutting off the fourth switching element at zero voltage is output. is there.

  According to the first invention, since the current flows uniformly to each switching element on the secondary side, the load on each switching element can be reduced and a switching element having a small capacity can be used. Further, since each protective reverse conducting diode connected in parallel with each switching element in reverse polarity acts as a rectifying element, a conventional secondary rectifying diode is not required. Further, according to the second invention, the turn-on loss and the turn-off loss are greatly reduced because each switching element is turned on and off at zero voltage and zero current when the EN / EP polarity or EP / EN polarity is switched.

[Embodiment 1]
FIG. 1 is an electrical connection diagram of the AC arc machining power supply device of the present invention. In FIG. 1, the primary rectifier circuit DR1 rectifies the output of the three-phase AC commercial power supply AC and converts it into a DC voltage, and the smoothing capacitor C1 smoothes the voltage converted into DC by the primary rectifier circuit DR1.

  The bridge-connected primary inverter circuit shown in FIG. 1 is formed by the fifth switching element TR5 to the eighth switching element TR8, and the fifth switching element TR5 and the eighth switching element that form opposite sides. TR8, a sixth switching element TR6, and a seventh switching element TR7 are each paired, and these pairs are set by a first element drive signal Sc1 to a fourth element drive signal Sc4 output from a main control circuit SC described later. The two elements that make up repeatedly turn on and off to convert a DC voltage into a high-frequency AC voltage. The primary inverter circuit uses a full bridge circuit, but may use a half bridge circuit.

  The fifth reverse conduction diode D5 to the eighth reverse conduction diode D8 are connected in parallel with the reverse polarity to the fifth switching element TR5 to the eighth switching element TR8, respectively. The main transformer INT converts the high-frequency AC voltage on the primary side into a voltage suitable for arc machining, and outputs the converted voltage to the first terminal and the second terminal provided on the secondary side.

  The bridge-connected secondary inverter circuit shown in FIG. 1 is formed by the first switching element TR1 to the fourth switching element TR4, and the first switching element TR1 and the fourth switching element that form opposite sides. TR4, the second switching element TR2 and the third switching element TR3 are each paired, and a first secondary element drive signal Sd1 to a fourth secondary element drive output from a secondary inverter control circuit SD described later. In response to the signal Sd4, these two pairs of elements repeat conduction and interruption, and output a predetermined low frequency AC voltage.

  Further, the emitter side of the first switching element TR1 is connected to the first terminal of the main transformer INT, the collector side is connected to the collector side of the second switching element TR2, and the collector side of the second switching element TR2 is connected to the above. Connected to the second terminal of the main transformer INT, connected the emitter side to the emitter side of the fourth switching element TR4, and connected the emitter side of the second switching element TR2 and the collector side of the fourth switching element TR4. The first reverse conducting diode D1 is connected to the first switching element TR1 in parallel with the reverse polarity, the second reverse conducting diode D2 is connected to the second switching element TR2 in parallel with the reverse polarity, 3 reverse conducting diodes D3 are connected in parallel to the third switching element TR3 in reverse polarity, and the fourth reverse conducting diode D4 is connected to the fourth switching diode D4. The switching element TR4 are connected in parallel to the opposite polarity to form a secondary inverter circuit.

  The output current detection circuit ID detects the output current and outputs it as an output current detection signal Id. The comparison operation circuit ER compares and calculates the output current setting signal Ir of the output current setting circuit IR and the output current detection signal Id, and outputs the value of the comparison operation signal Er = Ir−Id.

  The main control circuit SC responds to the value of the comparison operation signal Er = Ir-Id from the comparison operation circuit ER, and the first element drive signal Sc1, the fourth element drive signal Sc4, and the second element drive signal, which are main control signals. The ON period of Sc2 and the third element drive signal Sc3 is controlled.

  The DC / AC mode setting circuit MC sets the DC mode or the AC mode. In the DC mode, the DC / AC mode setting signal Mc is set to the Low level, and in the AC mode, the DC / AC mode setting signal Mc is set to the High level. And output.

  The polarity switching circuit TM sets the polarity switching frequency and polarity ratio of the secondary inverter circuit to predetermined values and outputs them as a polarity switching signal Tm.

  The secondary inverter control circuit SD outputs a second secondary element drive signal Sd2 and a third secondary element drive signal Sd3 when the DC mode is set by the DC / AC mode setting circuit MC, and outputs a secondary inverter. When the second switching element TR2 and the third switching element TR3 of the circuit are made conductive and set to the AC mode by the DC / AC mode setting circuit MC, the first secondary element is set according to the polarity switching signal Tm. The drive signal Sd1, the fourth secondary element drive signal Sd4, the second secondary element drive signal Sd2, and the third secondary element drive signal Sd3 are alternately output.

  2 is a configuration diagram for explaining the operation of the negative electrode EN of the AC arc machining power supply device shown in FIG. 1 and FIG. 3 is an EP operation of the electrode plus of the AC arc machining power supply device shown in FIG. FIG. 4 and 5 are waveform diagrams for explaining the EN operation and the EP operation.

(When electrode minus EN)
In the first conduction period T1 (time t1 to t2) shown in FIG. 4, the second switching element TR2 and the third switching element TR3 shown in FIG. 2A are in a conduction state, and the second switching element TR3 of the main transformer INT The secondary voltage Vt having a negative potential is output to the terminal, whereby the secondary current Vi shown in FIG. 2A is changed to the torch 1 (electrode), the secondary winding, the third switching element TR7, and the fourth reverse element. It flows in the order of the current-carrying diode D5 and the work piece 2.

  In the first switching period T2 (time t2 to t3), the second switching element TR2 and the third switching element TR3 shown in FIG. 2B are in a conductive state, and the first terminal and the first switching terminal of the main transformer INT The secondary voltage Vt at the two terminals becomes zero potential, so that the secondary current Vi shown in FIG. 2 (B) becomes the torch 1 (electrode), the secondary winding, the third switching element TR3, the fourth reverse energization. It flows through the path of the diode D4, the workpiece 2 and the path of the torch 1 (electrode), the secondary winding, the first reverse conducting diode D1, and the second switching element TR2.

  In the second conduction period T3 (time t3 to t4), the second switching element TR2 and the third switching element TR3 shown in FIG. 2C are in a conduction state, and a positive potential is applied to the first terminal of the main transformer INT. Secondary voltage Vt is output, and the secondary current Vi shown in FIG. 2C is changed to the torch 1 (electrode), the secondary winding, the first reverse conducting diode D1, the second switching element TR2, It flows in the order of the workpiece 2. As described above, when the secondary voltage Vt is negative, the secondary current Vi flows through the third switching element TR3 and the fourth reverse conducting diode D4, and when the secondary voltage Vt is positive, the first reverse conducting diode. The secondary current Vi flows through D1 and the second switching element TR2, and the secondary current Vi flows uniformly through the respective elements.

(Electrode plus EP)
In the first conduction period T1 (time t1 to t2) shown in FIG. 5, the first switching element TR1 and the fourth switching element TR4 shown in FIG. 3A are in the conduction state, and the first switching element TR1 of the main transformer INT. A secondary voltage Vt having a negative potential is output to the terminal, whereby the secondary current Vi shown in FIG. 3 (A) is changed to the workpiece 2, the second reverse conducting diode D2, the first switching element TR1, the secondary. The winding flows in the order of the torch 1 (electrode).

  In the first switching period T2 (time t2 to t3), the first switching element TR1 and the fourth switching element TR4 shown in FIG. 3B are in a conductive state, and the main transformer INT of the main transformer INT The secondary voltage Vt of the first terminal and the second terminal becomes zero potential, whereby the secondary current Vi shown in FIG. 3B is changed to the switching element TR1 of the work piece 2 and the second reverse conducting diodes D2 and 15. It flows through the path of the secondary winding and torch 1 (electrode) and the path of the work piece 2, the fourth switching element TR4, the third reverse conducting diode D3, the secondary winding and torch 1 (electrode).

  In the second conduction period T3 (time t3 to t4), the first switching element TR1 and the fourth switching element TR4 shown in FIG. 3C are in a conduction state, and are connected to the second first terminal of the main transformer INT. The secondary voltage Vt of the potential is output, so that the secondary current Vi shown in FIG. 3C is changed to the workpiece 2, the fourth switching element TR4, the third reverse conducting diode D3, the secondary winding, It flows in the order of torch 1 (electrode). Therefore, when the secondary voltage Vt is a negative potential, the secondary current Vi flows through the second reverse conducting diode D2 and the first switching element TR1, and when the secondary voltage Vt is a positive potential, the fourth switching element TR4. The secondary current Vi flows through the third reverse conducting diode D3, and the secondary current Vi flows uniformly through the elements. As described above, the output of the main transformer INT can be rectified by each of the reverse current-carrying diodes and the usage rate of each element can be made uniform.

[Embodiment 2]
FIG. 14 is an electrical connection diagram of the power supply device for AC arc machining of the second invention. In the figure, the same reference numerals as those in the electrical connection diagram of the AC arc machining power supply device of the present invention shown in FIG.

  In FIG. 14, the polarity switching synchronization circuit ST receives the polarity switching signal Tm, the first element driving signal Sc1, and the second element driving signal Sc2, and the polarity switching signal Tm is input to the first element driving signal Sc1 and the second element driving signal. The polarity switching synchronization signal St is output in synchronization with Sc2.

  6 and 7 are configuration diagrams for explaining the operation at the time of EN / EP switching of the AC arc machining power supply device shown in FIG. 1, and FIGS. 10 and 11 illustrate the operation at the time of EN / EP switching. FIG.

  The waveform of FIG. 10A shows the waveform of the polarity switching signal Tm, indicating the EP polarity when at the High level, and indicating the EN polarity when at the Low level. The waveform of FIG. 10B shows the secondary voltage Vt of the first terminal and the second terminal of the main transformer INT, the waveform of FIG. 10C shows the output current Io, and the waveform of FIG. The waveform indicates the first secondary element drive signal Sd1, the waveform in FIG. 10E indicates the second secondary element drive signal Sd2, and the waveform in FIG. 10F indicates the third secondary element drive signal Sd2. The element drive signal Sd3 is shown, and the waveform in FIG. 10G shows the fourth secondary element drive signal Sd4.

(AC mode EN / EP switching)
6 and 10, when the polarity switching signal Tm changes from low level to high level in the first conduction period T1 (negative potential period) shown in FIG. 10B, the polarity switching synchronization circuit ST displays the polarity switching signal Tm. Is output as a polarity switching synchronization signal St in synchronization with the first element driving signal Sc1 and the second element driving signal Sc2 (not shown), and the polarity switching synchronization signal St is output from the Low level to the High level. The secondary inverter control circuit SD determines that the polarity has been switched from the EN polarity to the EP polarity when the polarity switching synchronization signal St changes from the Low level to the High level, and in accordance with the polarity switching synchronization signal St, FIG. At the time t = t9 after the elapse of a predetermined time from the rising time t = t3 of the secondary voltage Vt shown, the first secondary element drive signal Sd1 is turned on and the third secondary element drive signal Sd3 is turned off. . At this time, in the period A shown in FIG. 10, the second switching element TR2 and the third switching element TR3 shown in FIG. 6A are in a conductive state, and a positive potential of 2 is applied to the first terminal of the main transformer INT. The secondary voltage Vt is output, whereby the secondary current Vi shown in FIG. 6A is changed to the torch 1 (electrode), the secondary winding, the first reverse conducting diode D1, the second switching element TR2, and the welding target. It flows in the order of thing 2.

  In the B period (time t = t9 to t4) of the second conduction period T3, the first switching element TR1 shown in FIG. 6B is in the conduction state, and the second switching element TR2 is in the cutoff state. Further, since the secondary voltage Vt having a positive potential is output to the first terminal of the main transformer INT, the secondary current Vi shown in FIG. 6B is generated by the torch 1 (electrode), the secondary winding, 1 reverse current-carrying diode D1, second switching element TR2, and work piece 2 flow in this order. At this time, at the time t = t9, the first switching element TR1 is turned on, and the secondary current Vi flows through the first reverse conducting diode D1 connected in parallel with the reverse polarity, so that zero voltage switching is performed. This reduces the switching loss at turn-on. Further, since the third switching element TR3 is turned off and turned off in a state where the secondary current Vi does not flow, the switching loss at the time of turn-off is also reduced.

  In the second switching period T4 illustrated in FIG. 10B, the first switching element TR1 and the second switching element TR2 illustrated in FIG. 6C are in a conductive state, and the third switching element TR3 and the fourth switching element TR3 The switching element TR4 of FIG. In addition, the secondary voltage Vt of the first terminal and the second terminal of the main transformer INT becomes zero potential, so that the secondary current Vi shown in FIG. 6C is changed to the torch 1 (electrode), the secondary winding, The first reverse energization diode D1, the second switching element TR2, and the work piece 2 flow while decreasing in order.

  In the third conduction period T5 shown in FIG. 10 (B), in accordance with the polarity switching synchronization signal St (not shown), a predetermined time from the falling time t = t5 of the secondary voltage Vt shown in FIG. 10 (B). At time t = t10 after the elapse of time, the second secondary element drive signal Sd2 is turned off and the fourth secondary element drive signal Sd4 is turned on. At this time, in the period D shown in FIG. 10, the first switching element TR1 and the second switching element TR2 shown in FIG. 6D are in a conductive state, and the third switching element TR3 and the fourth switching element TR4. Is in a cut-off state, and a negative secondary voltage Vt is output to the second terminal of the main transformer INT, whereby the secondary current Vi shown in FIG. The current flows while increasing in the order of the energization diode D2, the first switching element TR1, the secondary winding, and the torch 1 (electrode).

  In the E period (time t = t10 to t6) of the third conduction period T5, the second switching element TR2 shown in FIG. 6 (E) is cut off, and the fourth switching element TR4 is turned on and EN / EP polarity switching is completed. Further, a secondary voltage Vt having a negative potential is output to the second terminal of the main transformer INT, whereby the secondary current Vi shown in FIG. 6 (E) is supplied to the work piece 2, the second reverse conducting diode D2, The first switching element TR1, the secondary winding, and the torch 1 (electrode) flow in this order. At this time, at the time t = t10, the second switching element TR2 is turned off, and the secondary current Vi flows through the second reverse conducting diode D2 connected in parallel with the reverse polarity, so that zero voltage switching is performed. This reduces the switching loss during turn-off. Furthermore, since the fourth switching element TR4 is turned on and turned on in a state where the secondary current Vi does not flow, the switching loss at the time of turn-on is also reduced.

(AC mode second EN / EP switching)
7 and 11, when the polarity switching signal Tm changes from the Low level to the High level in the second conduction period T2 (positive potential period) shown in FIG. 11B, the polarity switching synchronization circuit ST displays the polarity switching signal Tm. Is output as a polarity switching synchronization signal St in synchronization with the first element driving signal Sc1 and the second element driving signal Sc2 (not shown), and the polarity switching synchronization signal St is output from the Low level to the High level. When the polarity switching synchronization signal St changes from the Low level to the High level, the secondary inverter control circuit SD determines that the polarity has been switched from the EN polarity to the EP polarity, and according to the polarity switching synchronization signal St, FIG. At the time t = t10 after the elapse of a predetermined time from the falling time t = t5 of the secondary voltage Vt shown, the fourth secondary element drive signal Sd4 is turned on and the second secondary element drive signal Sd2 is turned off. To do. At this time, in the period D shown in FIG. 11, the second switching element TR2 and the third switching element TR3 shown in FIG. 7A are in a conductive state, and a negative potential of 2 is applied to the second terminal of the main transformer INT. The secondary voltage Vt is output, whereby the secondary current Vi shown in FIG. 7A is changed to the torch 1 (electrode), the secondary winding, the third switching element TR3, the fourth reverse conducting diode D4, and the welding target. It flows in the order of thing 2.

  In the E period (time t = t10 to t6) of the third conduction period T5, the third switching element TR3 and the fourth switching element TR4 shown in FIG. Since the negative secondary voltage Vt is output to the two terminals, the secondary current Vi shown in FIG. 7B is obtained from the torch 1 (electrode), secondary winding, third switching element TR3, fourth The reverse current-carrying diode D4 and the work piece 2 flow in this order. At this time, at the time t = t10, the second switching element TR2 is turned off and turned off in a state where the secondary current Vi is not flowing, so that the switching loss at the time of turn-off is reduced. Further, the fourth switching element TR4 is turned on, and the secondary current Vi flows through the fourth reverse conducting diode D4 connected in parallel with the reverse polarity, so that the switching is performed with zero voltage and the switching loss at the turn-on is also reduced. Decrease.

  In the second switching period T6 shown in FIG. 11B, the third switching element TR3 and the fourth switching element TR4 shown in FIG. 7C are in a conductive state, and the first switching element TR1 and the second switching element TR1 The switching element TR2 is in a cut-off state. In addition, the secondary voltage Vt of the first terminal and the second terminal of the main transformer INT becomes zero potential, so that the secondary current Vi shown in FIG. 7C is changed to the torch 1 (electrode), the secondary winding, It flows while decreasing in the order of the third switching element TR3 and the fourth reverse conducting diode D4.

  In the fourth conduction period T7 shown in FIG. 11 (B), a predetermined time from the rising time t = t7 of the secondary voltage Vt shown in FIG. 11 (B) according to the polarity switching synchronization signal St (not shown). At time t = t11 after the lapse of time, the first secondary element drive signal Sd1 is turned on and the third secondary element drive signal Sd3 is turned off. At this time, in the G period shown in FIG. 11, the third switching element TR3 and the fourth switching element TR4 shown in FIG. 7D are in a conductive state, and the first switching element TR1 and the second switching element TR2 are in the conductive state. Is in a cut-off state, and a positive secondary voltage Vt is output to the first terminal of the main transformer INT, whereby the secondary current Vi shown in FIG. It flows while increasing in the order of the element TR4, the third reverse conducting diode D3, the secondary winding, and the torch 1 (electrode).

  In the H period (time t = t11 to t12) of the fourth conduction period T7, the third switching element TR3 shown in FIG. 7E is cut off, and the first switching element TR1 is turned on and EN / EP polarity switching is completed. Further, the secondary voltage Vt having a positive potential is output to the first terminal of the main transformer INT, whereby the secondary current Vi shown in FIG. 7 (E) is supplied to the work piece 2, the fourth switching element TR4, and the second switching element TR4. 3 reverse current-carrying diode D3, secondary winding, and torch 1 (electrode) in this order. At this time, at the time t = t11, the first switching element TR1 is turned on, and is turned on in a state where the secondary current Vi is not flowing. Therefore, the switching loss at the time of turn-on is reduced. Furthermore, since the third switching element TR3 is turned off and the secondary current Vi flows through the third reverse conducting diode D3 connected in parallel with the reverse polarity, switching is performed with zero voltage, and switching loss at the time of turn-off is also caused. Decrease.

  FIGS. 8 and 9 are configuration diagrams for explaining the operation at the time of EP / EN switching of the AC arc machining power supply device shown in FIG. 1, and FIGS. 12 and 13 illustrate the operation at the time of EP / EN switching. FIG.

  The waveform in FIG. 12A shows the waveform of the polarity switching signal Tm, indicating the EP polarity when at the High level, and indicating the EN polarity when at the Low level. The waveform of FIG. 12B shows the secondary voltage Vt of the first terminal and the second terminal of the main transformer INT, the waveform of FIG. 12C shows the output current Io, and the waveform of FIG. The waveform indicates the first secondary element drive signal Sd1, the waveform in FIG. 12E indicates the second secondary element drive signal Sd2, and the waveform in FIG. 12F indicates the third secondary element drive signal Sd1. The element drive signal Sd3 is shown, and the waveform of FIG. 12G shows the fourth secondary element drive signal Sd4.

(AC mode EP / EN switching)
8 and 12, when the polarity switching signal Tm changes from the High level to the Low level in the first conduction period T1 (negative potential period) shown in FIG. 12B, the polarity switching synchronization circuit ST displays the polarity switching signal Tm. Is output as a polarity switching synchronization signal St in synchronization with the first element driving signal Sc1 and the second element driving signal Sc2 (not shown), and the polarity switching synchronization signal St is output from the High level to the Low level. The secondary inverter control circuit SD determines that the EP polarity is switched to the EN polarity when the polarity switching synchronization signal St changes from the High level to the Low level, and the rising time t = of the secondary voltage Vt shown in FIG. At time t = t9 after the elapse of a predetermined time from t3, the first secondary element drive signal Sd1 is turned off and the third secondary element drive signal Sd3 is turned on. At this time, during the period A shown in FIG. 12, the second switching element TR2 and the third switching element TR3 in FIG. 8A are in a cut-off state, and a positive potential secondary is applied to the first terminal of the main transformer INT. The voltage Vt is output, whereby the secondary current Vi shown in FIG. 8A is changed in the order of the work piece 2, the fourth switching element TR4, the third reverse conducting diode D3, the secondary winding, and the torch 1. Flowing.

  In the B period (time t = t9 to t4) of the second conduction period T3, the third switching element TR3 is turned on and the first switching element TR1 is turned off in FIG. 8B. Further, since the secondary voltage Vt having a positive potential is output to the first terminal of the main transformer INT, the secondary current Vi shown in FIG. 8B is to be welded 2, the 84th switching element TR4, 3 reverse current-carrying diode D3, secondary winding, and torch 1 flow in this order. At this time, at the time t = t9, the third switching element TR3 is turned on, and the secondary current Vi flows through the third reverse conducting diode D3 connected in parallel with the reverse polarity, so that zero voltage switching is performed. This reduces the switching loss at turn-on. Further, since the second switching element TR3 is turned off and turned off in a state where the secondary current Vi does not flow, the switching loss at the time of turn-off is reduced.

  In the second switching period T4 shown in FIG. 12B, the third switching element TR3 and the fourth switching element TR4 in FIG. 8C are in a conductive state, and the first switching element TR1 and the second switching element TR4 The switching element TR2 is in a cut-off state. Further, the secondary voltage Vt of the first terminal and the second terminal of the main transformer INT becomes zero potential, so that the secondary current Vi shown in FIG. 8C is the workpiece 2 and the fourth switching element TR4. The third reverse conducting diode D3, the secondary winding, and the torch 1 decrease while flowing in this order.

  In the third conduction period T5 shown in FIG. 12B, a predetermined time from the time t = t5 of the fall time of the secondary voltage Vt shown in FIG. 12B according to the polarity switching synchronization signal (not shown). At time t = t10 after the lapse of time, the second secondary element drive signal Sd2 is turned on and the fourth secondary element drive signal Sd4 is turned off. At this time, in the period D shown in FIG. 12, the third switching element TR3 and the fourth switching element TR4 in FIG. 8D are in a conductive state, and the first switching element TR1 and the second switching element TR2 are in the conductive state. In the cut-off state, a negative secondary voltage Vt is output to the second terminal of the main transformer INT, whereby the secondary current Vi shown in FIG. The switching element TR3, the fourth reverse conducting diode D4, and the work piece 2 flow in increasing order.

  In the E period (time t = t10 to t6) of the third conduction period T5, the fourth switching element TR4 is cut off and the third switching element TR3 is turned on in FIG. Polarity switching is complete. Further, a secondary voltage Vt having a negative potential is output to the second terminal of the main transformer INT, whereby the secondary current Vi shown in FIG. 8 (E) is supplied to the torch, the secondary winding, and the third switching element. It flows in the order of TR3, fourth reverse conducting diode D4, and work piece 2. At this time, at the time t = t10, the second switching element TR2 is turned on, and is turned on in a state where the secondary current Vi is not flowing. Therefore, the switching loss at the turn-on is reduced. Further, in the fourth switching element TR4, since the secondary current Vi flows through the fourth reverse conducting diode D4 connected in parallel with the reverse polarity, zero voltage switching is performed and the switching loss at the time of turn-off is reduced.

(AC mode 2nd EP / EN switching)
9 and 13, when the polarity switching signal Tm changes from the High level to the Low level in the second conduction period T3 (positive potential period) shown in FIG. 13B, the polarity switching synchronization circuit ST displays the polarity switching signal Tm. Is output as a polarity switching synchronization signal St in synchronization with the first element driving signal Sc1 and the second element driving signal Sc2 (not shown), and the polarity switching synchronization signal St is output from the High level to the Low level. When the polarity switching synchronization signal St changes from the High level to the Low level, the secondary inverter control circuit SD determines that the EP polarity is switched to the EN polarity, and according to the polarity switching synchronization signal St, as shown in FIG. At time t = t10 after the elapse of a predetermined time from the falling time t = t5 of the secondary voltage Vt, the second secondary element drive signal Sd2 is turned on and the fourth secondary element drive signal Sd4 is turned off. At this time, during the period D shown in FIG. 13, the second switching element TR2 and the third switching element TR3 in FIG. 9A are in the cut-off state, and the secondary terminal of the negative potential is applied to the second terminal of the main transformer INT. The voltage Vt is output, so that the secondary current Vi shown in FIG. 9A is changed in the order of the work piece 2, the second reverse conducting diode D2, the fourth switching element TR4, the secondary winding, and the torch 1. Flowing.

  In the E period (time t = t10 to t6) of the second conduction period T3, the second switching element TR2 illustrated in FIG. 9B is in a conduction state, and the fourth switching element TR4 is in a cutoff state. Further, since the secondary voltage Vt having a negative positive potential is output to the second terminal of the main transformer INT, the secondary current Vi shown in FIG. 9B is the workpiece 2 and the second reverse conducting diode. D2 flows in the order of the first switching element TR1, the secondary winding, and the torch 1. At this time, at the time t = t10, the second switching element TR2 is turned on, and the secondary current Vi flows through the second reverse conducting diode D2 connected in parallel with the reverse polarity, so that zero voltage switching is performed. This reduces the switching loss at turn-on. Further, since the fourth switching element TR4 is turned off and turned off in a state where the secondary current Vi does not flow, the switching loss at the time of turn-off is reduced.

  In the third switching period T6 shown in FIG. 13B, the first switching element TR1 and the second switching element TR2 are in the conductive state in FIG. 9C, and the third switching element TR3 and the fourth switching element are switched. The element TR4 is in a cut-off state. Further, the secondary voltage Vt of the first terminal and the second terminal of the main transformer INT becomes zero potential, whereby the secondary current Vi shown in FIG. 8C is the workpiece 2 and the fourth reverse conducting diode D4. The first switching element TR1, the secondary winding, and the torch 1 decrease while flowing in this order.

  In the fourth conduction period T7 shown in FIG. 13B, a predetermined time has elapsed from the rising time t = t7 of the secondary voltage Vt shown in FIG. 13B according to the polarity switching synchronization signal St not shown. At a later time t = t11, the first secondary element drive signal Sd1 is turned off and the third secondary element drive signal Sd3 is turned on. At this time, in the G period shown in FIG. 13, the first switching element TR1 and the second switching element TR2 are in the conductive state in FIG. 9D, and the third switching element TR3 and the fourth switching element TR4 are in the conductive state. The secondary voltage Vt having a positive potential is output to the first terminal of the main transformer INT, and the secondary current Vi shown in FIG. The reverse current-carrying diode D1, the second switching element TR2, and the work piece 2 increase in this order.

  In the H period (time t = t11 to t12) of the third conduction period T5, the fourth switching element TR4 is cut off and the third switching element TR3 is turned on in FIG. Polarity switching is complete. In addition, a positive secondary voltage Vt is output to the first terminal of the main transformer INT, so that the secondary current Vi shown in FIG. The current flows in the order of the energization diode D1, the second switching element TR2, and the work piece 2. At this time, at the time t = t11, the first switching element TR1 is turned off, and the secondary current Vi flows through the first reverse conducting diode D1 connected in parallel with the reverse polarity, so that zero voltage switching is performed. This reduces the switching loss during turn-off. Further, since the third switching element TR3 is turned on and turned on in a state where the secondary current Vi is not flowing, the switching loss at the time of turn-on is reduced.

It is an electrical connection diagram of the power supply device for AC arc machining of the present invention. FIG. 2 is a configuration diagram for explaining an operation at the time of EN of the AC arc machining power supply device shown in FIG. 1. FIG. 2 is a configuration diagram for explaining the operation of the AC arc machining power supply device shown in FIG. 1 during EP. FIG. 3 is a waveform diagram illustrating an operation at the time of EN shown in FIG. 2. It is a wave form diagram explaining the operation | movement at the time of EP shown in FIG. FIG. 2 is a configuration diagram for explaining an operation at the time of EN / EP switching of the AC arc machining power supply device shown in FIG. 1. FIG. 5 is a second configuration diagram for explaining the operation at the time of switching between EN and EP of the AC arc machining power supply device shown in FIG. 1. FIG. 2 is a configuration diagram illustrating an operation at the time of EP / EN switching of the AC arc machining power supply device shown in FIG. 1. FIG. 5 is a second configuration diagram for explaining an operation at the time of EP / EN switching of the AC arc machining power supply device shown in FIG. 1. It is a wave form diagram explaining the operation | movement at the time of EN / EP switching shown in FIG. It is a wave form diagram explaining the operation | movement at the time of EN / EP switching shown in FIG. It is a wave form diagram explaining the operation | movement at the time of EP / EN switching shown in FIG. It is a wave form diagram explaining the operation | movement at the time of EP / EN switching shown in FIG. It is an electrical connection figure of the power supply device for alternating current arc processing of 2nd this invention. It is an electrical connection figure of the power supply device for alternating current arc processing of a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Torch 2 Workpiece AC Commercial AC power supply C1 Smoothing capacitor D1 1st reverse conducting diode D2 2nd reverse conducting diode D3 3rd reverse conducting diode D4 4th reverse conducting diode D5 5th reverse conducting diode D6 5th 6 reverse conducting diode D7 7th reverse conducting diode D8 8th reverse conducting diode DR1 primary rectifier circuit DR2 secondary rectifier circuit ER comparison operation circuit ID output current detection circuit IR output current setting circuit INT main transformer KD secondary Inverter drive circuit MC DC / AC mode setting circuit SC Main control circuit SD Secondary inverter control circuit TS Start switch TM Polarity switching circuit TR1 First switching element (first element)
TR2 Second switching element (second element)
TR3 Third switching element (third element)
TR4 Fourth switching element (fourth element)
TR5 Fifth switching element (fifth element)
TR6 Sixth switching element (sixth element)
TR7 Seventh switching element (seventh element)
TR8 Eighth switching element (eighth element)
Er comparison calculation signal Id output current detection signal Ir output current setting signal Mc DC / AC mode setting signal Sc1 first element drive signal Sc2 second element drive signal Sc3 third element drive signal Sc4 fourth element drive signal Sd1 first 2 Secondary element drive signal Sd2 Second secondary element drive signal Sd3 Third secondary element drive signal Sd4 Fourth secondary element drive signal Tm Polarity switching signal Ts Start switch Vt Secondary winding secondary winding Voltage

Claims (2)

  A DC power supply circuit that outputs a DC voltage; an inverter circuit that converts the output of the DC power supply circuit into a high-frequency AC voltage; a main control circuit that outputs a main control signal for controlling the inverter circuit; and arcing the high-frequency AC voltage A main transformer that converts the converted voltage into a voltage suitable for processing and outputs the converted voltage to a first terminal and a second terminal provided on the secondary side; and an emitter of a first switching element at the first terminal of the main transformer The first switching element that connects the first switching element, the second switching element that connects the collector side of the second switching element to the collector side of the first switching element, and the second terminal of the main transformer The third switching element for connecting the collector side of the third switching element and the emitter side of the fourth switching element for the emitter of the third switching element. The fourth switching element connected to the side, the first reverse conducting diode connected in parallel to the first switching element in reverse polarity, and the second reverse conducting diode connected in parallel to the second switching element in reverse polarity A third reverse conducting diode connected in parallel to the third switching element in reverse polarity; a fourth reverse conducting diode connected in parallel to the fourth switching element in reverse polarity; and the emitter side of the second switching element To be connected to a connection point between the first switching element and the collector side of the fourth switching element, an electrode connected to an intermediate terminal on the secondary side of the main transformer, an EN polarity of the electrode minus, and an EP of the electrode plus A polarity switching circuit that outputs a polarity switching signal for switching to a polarity; and the first switching element and the polarity switching circuit that receives the polarity switching signal and makes the electrode negative. A second inverter control circuit for conducting the second switching element and the third switching element when the third switching element is made conductive and the electrode is made positive with the EP polarity, and the electrode has a negative EN polarity. When the output voltage of the first terminal of the main transformer is a positive potential, a current is passed through the path of the electrode, the first reverse conducting diode, the second switching element, and the workpiece, and the second terminal of the main transformer When the output voltage is a negative potential, a current is passed through the electrode, the third switching element, the fourth reverse conducting diode, and the path of the workpiece, and the electrode has a positive EP polarity and the first terminal of the main transformer. When the output voltage of the main transformer is a positive potential, a current is passed through the workpiece, the fourth switching element, the third reverse conducting diode, and the electrode path, and the output voltage of the second terminal of the main transformer is a negative potential. To be welded A power supply device for AC arc machining, wherein a current is passed through a path of an object, a second reverse conducting diode, a first switching element, and an electrode. A polarity switching synchronization circuit is provided between the polarity switching circuit and the secondary inverter control circuit, and the polarity switching synchronization circuit receives the polarity switching signal and the main control signal and converts the polarity switching signal into the main control signal. When the EN / EP polarity is switched so that the electrode switches from negative to positive, the first switching element is turned on at zero voltage and the third switching element is turned on during the first conduction period of the main control signal. EP / ENP polarity switching when the current is cut off, the second switching element is cut off at zero voltage and the fourth switching element is turned on at zero current during the second conduction period, and the electrode switches from positive to negative The first switching element is cut off at zero current during the first conduction period of the main control signal, the third switching element is turned on at zero voltage, and the second switching period is established during the second conduction period. AC arc machining power supply apparatus according to claim 1, wherein the outputting the polarity switching 換同 phase signal to cut off the fourth switching element in the zero voltage conducts the switching element at zero current.

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