JP2009148118A - Power supply unit and arc machining power supply unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply unit that ensures charging and discharging of auxiliary capacitors for soft switching control and that reduces switching loss and suppresses voltage surge. <P>SOLUTION: A resonance circuit 15 is provided between a connection point N2 between switching elements S1, S2 of an inverter circuit 13 and a connection point N1 between the auxiliary capacitors C1, C2 of an auxiliary switching circuit 14. The resonance circuit 15 performs resonance operation before switching elements S3, S4 are each turned off to start discharging the auxiliary capacitors C1, C2, and generates a resonance current that increases the output currents of the switching elements S1, S2 based on the discharge currents of the auxiliary capacitors C1, C2. Thereby, the discharge speed of the auxiliary capacitors C1, C2 becomes fast, so that the discharge time of the auxiliary capacitors C1, C2 is shortened. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply device having an inverter circuit and a power supply device for arc machining.

  For example, as disclosed in Patent Document 1, a power supply device used for an arc machine or the like is a DC converter that converts a commercial power supply (three-phase AC power supply) into a DC voltage that is rectified by a rectifier circuit and smoothed by a smoothing capacitor. A circuit and an inverter circuit composed of a half-bridge circuit of two switching elements. The inverter circuit converts the DC voltage from the DC conversion circuit into a predetermined high-frequency AC voltage by alternately turning on and off the two switching elements. A predetermined high-frequency AC voltage from the inverter circuit is further converted into a DC voltage for arc machining suitable for arc machining such as arc welding or arc cutting.

Further, in the power supply device disclosed in Patent Document 1, an auxiliary capacitor is connected between a pair of power supply lines between a smoothing capacitor and an inverter circuit constituting a DC conversion circuit, and each power supply line between the smoothing and the auxiliary capacitor is connected to each other. Auxiliary switching elements are arranged in each. Each auxiliary switching element is turned on and off as a pair with a pair of switching elements of the inverter circuit. When the switching element is on, the switching element of the inverter circuit and the auxiliary switching element are simultaneously turned on for each group. When the switching element is off, the switching element of the inverter circuit is turned on. The auxiliary switching element is turned off before turning off. By utilizing the charge / discharge operation of the auxiliary capacitor associated with the operation of the switching element and the auxiliary switching element of the inverter circuit, soft switching control is performed to reduce switching loss in each switching element.
JP 2005-279774 A

  However, the charging and discharging of the auxiliary capacitor may be incomplete during light load or no load. This incomplete charging / discharging operation of the auxiliary capacitor leads to an increase in switching loss and breakage of the switching element due to the generation of a surge voltage. Therefore, it is desired to solve these problems.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to ensure charging / discharging of the auxiliary capacitor used in soft switching control regardless of the load state, to reduce switching loss and to suppress voltage surge. An object of the present invention is to provide a power supply device and an arc machining power supply device capable of achieving the above.

  In order to solve the above-mentioned problem, the invention according to claim 1 includes a rectifier circuit and first and second smoothing capacitors connected in series between a pair of power supply lines on the output side thereof, and an input AC power supply is provided. It comprises a direct current conversion circuit for converting into a rectified and smoothed direct current voltage and a half bridge circuit using first and second switching elements, and the first and second switching elements are alternately turned on and off to An inverter circuit that converts the DC voltage supplied via a power line into a predetermined AC voltage, and first and second connected in series between the power lines between the smoothing capacitor and the inverter circuit A third and a second capacitor which have an auxiliary capacitor and are alternately operated in pairs with the first and second switching elements on each power line between the smoothing capacitor and the auxiliary capacitor; An auxiliary switching circuit in which each of the switching elements is arranged, and the third and fourth switching elements are in the first and second switching states when the corresponding first and second auxiliary capacitors are charged. A power supply apparatus configured to perform soft switching control in which each of the first and second switching elements is turned off after the corresponding first and second auxiliary capacitors are discharged before the elements are turned off. The third and fourth switching elements are provided between the first and second switching elements and between the first and second auxiliary capacitors and start discharge of the first and second auxiliary capacitors. Each of the first and second switching elements based on the discharge current of the auxiliary capacitor, which resonates before each switching element is turned off or before each switching element is off Further comprising a resonant circuit to generate a resonance current to increase the output current of the device and its gist.

  In the present invention, a resonance circuit is provided between the first and second switching elements of the inverter circuit and between the first and second auxiliary capacitors of the auxiliary switching circuit, and the resonance circuit includes the first and second resonance circuits. The third switching element and the fourth switching element, which start discharging the auxiliary capacitor, resonate before each turn-off, and the output currents of the first and second switching elements increase based on the discharge current of the auxiliary capacitor. Such a resonance current is generated. Thereby, the discharge speed of the auxiliary capacitor is increased, and the discharge time of the auxiliary capacitor is shortened. Therefore, the auxiliary capacitor is discharged quickly in a short time, and the auxiliary capacitor can be surely discharged even during light load or no load.

  According to a second aspect of the present invention, in the power supply device according to the first aspect, the resonance circuit converts the resonance current to the opposite set based on each off state of the first and second switching elements. The gist of the present invention is to supply charging currents for the first and second auxiliary capacitors, respectively.

  In the present invention, based on each OFF of the first and second switching elements, the resonance circuit supplies the resonance current as the charging current of the auxiliary capacitor on the side opposite to the auxiliary capacitor that has been discharged. As a result, the resonance current from the resonance circuit is also used as the charging current for the auxiliary capacitor in the opposite group, so that the charging speed of the auxiliary capacitor is increased and the charging time of the auxiliary capacitor is shortened. Therefore, the auxiliary capacitor can be charged quickly in a short time, and the auxiliary capacitor can be reliably charged even during light loads or no loads.

  According to a third aspect of the present invention, in the power supply device according to the first or second aspect, the resonance circuit includes a freewheeling diode and is operated alternately in pairs with the third and fourth switching elements. The fifth and sixth switching elements and a resonant inductor are provided, and the fifth and sixth switching elements are arranged in opposite directions on both sides of the resonant inductor, one of which is the first and second switching elements. The gist is that the other is connected between the first and second auxiliary capacitors between the switching elements.

  According to the present invention, the resonant circuit includes a free wheel diode, and the fifth and sixth switching elements that are alternately operated in pairs with the third and fourth switching elements are opposite to each other so that both sides of the resonant inductor are provided. And one of the fifth and sixth switching elements is connected between the first and second switching elements, and the other is connected between the first and second auxiliary capacitors. That is, the resonance circuit can be simply configured with two switching elements and the resonance inductor.

  According to a fourth aspect of the present invention, in the power supply device according to the third aspect, the fifth and sixth switching elements are turned on prior to turning off the corresponding third and fourth switching elements. Is the gist.

  In the present invention, the fifth and sixth switching elements of the resonance circuit are turned on before the corresponding third and fourth switching elements are turned off, and a resonance operation is performed by the resonance inductor. That is, the fifth and sixth switching elements of the resonance circuit are turned on before the third and fourth switching elements are turned off, so that the resonance current of the inductor that rises slowly before the auxiliary capacitor starts discharging ( Resonance energy) can be increased in advance, whereby the discharge of the auxiliary capacitor is accelerated when the discharge of the auxiliary capacitor is started by turning off the third and fourth switching elements. Therefore, the discharge time of the auxiliary capacitor is further shortened.

  The invention according to claim 5 uses the power supply device according to any one of claims 1 to 4 to generate an arc machining voltage for arc machining of a workpiece. Power supply device.

  In this invention, since the power supply device according to any one of claims 1 to 4 is used to configure the power supply device for arc machining, the power supply device for arc machining that can obtain the effects of the above-mentioned respective claims is provided. Can be provided.

  According to the present invention, it is possible to provide a power supply apparatus and an arc machining power supply apparatus that can reliably charge and discharge an auxiliary capacitor used in soft switching control regardless of a load state, and can reduce switching loss and voltage surge. be able to.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 shows an arc machine 10 provided with a power supply device 11 for arc machining of this embodiment. The arc machine 10 supplies the machining DC voltage output from the power supply device 11 to the torch TH, and generates an arc from the torch TH toward the workpiece M, thereby causing the workpiece M to be processed. It is a device that performs arc processing such as arc welding and arc cutting.

  The arc machining power supply 11 includes a DC conversion circuit 12 that converts an input commercial power supply (three-phase AC voltage) of, for example, 200 V or 400 V into a DC voltage, and an inverter circuit that converts the DC voltage into a predetermined high-frequency AC voltage. 13.

  The DC conversion circuit 12 is configured by a bridge circuit using a diode, and is connected between a primary side rectifier circuit DR1 for full-wave rectification of a three-phase input AC power supply, and power supply lines L1 and L2 on the output side of the rectifier circuit DR1. Two smoothing capacitors Ca and Cb having the same capacity for smoothing the output voltage of the rectifier circuit DR1 are provided. The DC conversion circuit 12 generates a DC voltage from the input AC power supply by the rectifier circuit DR1 and the smoothing capacitors Ca and Cb.

  The inverter circuit 13 is connected to the power supply lines L1 and L2, and is configured by a half bridge circuit using two switching elements S1 and S2 made of IGBT. These switching elements S1 and S2 are reversely connected to freewheeling diodes D1 and D2, respectively. Each switching element S1, S2 is alternately turned on and off based on a control signal from the output control circuit SC input to the gate, converts the DC voltage output from the DC conversion circuit 12 into a predetermined high-frequency AC voltage, The high-frequency AC voltage is supplied to the primary coil of the transformer INT.

In the present embodiment, an auxiliary switching circuit 14 and a resonance circuit 15 are provided between the inverter circuit 13 and the DC conversion circuit 12.
The auxiliary switching circuit 14 includes two switching elements S3 and S4 made of IGBT, two auxiliary capacitors C1 and C2, and two free-wheeling diodes D7 and D8. The switching element S3 is disposed on the power supply line L1 subsequent to the smoothing capacitors Ca and Cb, and the switching element S4 is disposed on the power supply line L2 subsequent to the capacitors C1 and C2. Reflux diodes D3 and D4 are reversely connected to the switching elements S3 and S4, respectively. The switching elements S3 and S4 are alternately turned on and off based on a control signal from the output control circuit SC input to the gate.

  Freewheeling diodes D7 and D8 are connected in series between the power supply lines L1 and L2 at the subsequent stage of the switching elements S3 and S4. The freewheeling diodes D7 and D8 are connected in the forward direction from the power supply line L2 toward the power supply line L1. Connected to be. Auxiliary capacitors C1 and C2 having the same capacity are connected in series between the power supply lines L1 and L2 at the subsequent stage of the free-wheeling diodes D7 and D8. A connection point N1 between the auxiliary capacitors C1 and C2 is connected to a connection point between the freewheeling diodes D7 and D8 and a connection point between the smoothing capacitors Ca and Cb.

  The resonance circuit 15 is connected between a connection point N1 between the auxiliary capacitors C1 and C2 and a connection point N2 between the switching elements S1 and S2 of the inverter circuit 13. The resonance circuit 15 includes two switching elements S5 and S6 made of IGBT and two inductors (resonance inductor Lr and series inductor Ls). The switching element S5 has a collector connected to the connection point N2, and an emitter connected to the emitter of the switching element S6 via a resonant inductor Lr. The collector of the switching element S6 is connected to the connection point N1. Reflux diodes D5 and D6 are reversely connected to the switching elements S5 and S6, respectively. The switching elements S5 and S6 are alternately turned on and off based on a control signal from the output control circuit SC input to the gate. The series inductor Ls has one end connected to the connection point N2 and the other end connected to the connection point N1 via the primary coil of the transformer INT.

  Each of the switching elements S3 to S6 in the auxiliary switching circuit 14 and the resonance circuit 15 is turned on / off accompanying the operation of the switching elements S1 and S2 of the inverter circuit 13 to reduce the switching loss of the switching elements S1 and S2. And soft switching control which reduces the switching loss of switching element S3-S6 itself is performed. Details of this control will be described later together with the control of the inverter circuit 13.

  The high-frequency AC voltage generated by the inverter circuit 13 is supplied to the primary coil of the transformer INT, and the secondary side rectifier circuit DR2 and the DC reactor DCL are provided on the secondary side of the transformer INT. The secondary side rectifier circuit DR2 includes two diodes D11 and D12 each having an anode connected to both ends of the secondary coil of the transformer INT, and the rectifier circuit DR2 to which the cathodes of the diodes D11 and D12 are connected. A DC reactor DCL is connected to the output side. DC reactor DCL is connected to torch TH via output line L3. The secondary side rectifier circuit DR2 and the DC reactor DCL convert the high-frequency AC voltage from the inverter circuit 13 into an arc machining DC voltage and output it to the torch TH. On the other hand, the output line L4 connected to the intermediate tap of the secondary coil of the transformer INT is connected to the workpiece M, and from the torch TH to the workpiece M based on the supply of the arc machining DC voltage to the torch TH. An arc is generated toward it.

  Next, the control of the output control circuit SC that controls the switching elements S1 and S2 of the inverter circuit 13 and the switching elements S3 to S6 of the auxiliary switching circuit 14 and the resonance circuit 15 will be described with reference to FIG. To do. In FIG. 2, “S1” to “S6” indicate the on / off states of the switching elements S1 to S6, and the subscripts “s1 to s6, c1, c2, and d7 of the voltage“ V ”and the current“ I ”. , D8 "is associated with the code of each element. Further, the subscripts “s1 to s6” include freewheeling diodes D1 to D6. Voltage “V” and current “I” indicate voltage and current changes applied to each element.

  The output control circuit SC first turns on and off the switching elements S1 and S2 of the inverter circuit 13 alternately at a predetermined frequency in order to generate a high-frequency AC voltage from the DC voltage as the main operation of the inverter circuit 13. Here, the output control circuit SC detects the actual output current value from the output line L4 and the like, and performs the PWM control based on the actual output current value and the output set value, that is, the on-pulse width W (duty). The on-time of the switching elements S1 and S2 is adjusted by the change, and the high-frequency AC voltage is controlled.

  The output control circuit SC operates the switching elements S3 and S5 in combination with the switching element S1 of the inverter circuit 13, and operates the switching elements S4 and S6 in combination with the switching element S2, so that the main operation of the inverter circuit 13 is performed. Along with the soft switching control, the switching elements S3 to S6 of the auxiliary switching circuit 14 and the resonance circuit 15 are operated.

  More specifically, the output control circuit SC simultaneously turns on the switching element S3 of the auxiliary switching circuit 14 on the on side of the switching element S1 of the inverter circuit 13. On the other hand, on the off side of the switching element S1 of the inverter circuit 13, the output control circuit SC turns off the switching element S3 a predetermined time T1 before the off, and further turns the switching element S3 off a predetermined time T2 before the off. The switching element S5 of the resonance circuit 15 is turned on. Then, the output control circuit SC turns off the switching element S5 simultaneously with turning on the other pair of switching elements S2 and S4. Incidentally, at least the other pair of switching elements S2, S4, and S6 is maintained in the OFF state between the switching elements S1 and S3 being turned on and the switching element S5 being turned off. The on / off operation of the other pair of switching elements S2, S4, S6 is performed after the switching elements S2, S4 are turned on in the same manner as the on / off operation of the switching elements S1, S3, S5.

  According to the switching control of the output control circuit SC, when the current and voltage changes in each part of the circuit at each timing are viewed, first, the switching elements S1 and S3 are turned on, and the switching elements S2, S4 to S6 are turned off. Before time t0, the voltage across the smoothing capacitor Ca (auxiliary capacitor C1) is supplied to the switching element S1 of the inverter circuit 13. The output voltage from the switching element S1 is supplied to the primary coil of the transformer INT via the series inductor Ls. Accordingly, on the secondary side of the transformer INT, the DC voltage is applied from the diode D11 side of the secondary rectifier circuit DR2. A direct current voltage for arc machining is output to the torch TH through the reactor DCL.

  At “time t0”, the switching element S5 is turned on. Based on this ON, the resonance circuit 15 resonates, a resonance current is generated in the resonance inductor Lr, and this resonance current flows through the path from the connection point N2 to the switching element S5, the resonance inductor Lr, and the freewheeling diode D6. As a result, the current Is5 flowing through the switching element S5 increases, and the current (output current) Is1 flowing through the switching element S1 also increases in conjunction with this. Note that since the resonance current generated by the resonance inductor Lr rises slowly from zero, the switching element S5 is turned on at zero current, and the switching loss is reduced. From the switching element S1, the supply of the output voltage based on the voltage between the terminals of the smoothing capacitor Ca is continued on the primary coil side of the transformer INT. On the secondary side of the transformer INT, the DC reactor DCL from the diode D11 side is supplied. Current supply continues. The terminal voltage of the auxiliary capacitor C1 is still maintained equal to the terminal voltage of the smoothing capacitor Ca.

  At “time t1”, the switching element S3 is turned off. Although the supply of the inter-terminal voltage from the smoothing capacitor Ca to the switching element S1 is cut off based on this off, the discharge of the auxiliary capacitor C1 is started and replaced with the supply of the inter-terminal voltage of the capacitor C1. When the switching element S3 is turned off, the voltage across the auxiliary capacitor C1 is charged to the voltage across the smoothing capacitor Ca before the time t1, so that the switching element S3 is set to zero voltage (the potential difference between the terminals is zero). ) And the switching loss is reduced. From the switching element S1, the supply of the output voltage based on the voltage across the terminal of the auxiliary capacitor C1 is continued to the primary coil side of the transformer INT, and the direct current from the diode D11 side is similarly applied to the secondary side of the transformer INT. Current supply to reactor DCL is continued.

  Also at this time, the current Is1 flowing through the switching element S1 is larger than the current value when the current flows only on the primary coil side of the transformer INT, and in this embodiment, the current Is5 flowing through the switching element S5 is Since it is set to increase further than immediately before time t1, the current Is1 flowing through the switching element S1 further increases in conjunction with this. Thereby, the discharge speed of the auxiliary capacitor C1 is increased, and the discharge time of the auxiliary capacitor C1 is shortened. Therefore, the auxiliary capacitor C1 is quickly discharged in a short time before the switching element S1 is turned on.

  When the discharge of the auxiliary capacitor C1 is completed at “time t2,” the return current flows through the switching element S1 in the on state, the primary coil (series inductor Ls) side of the transformer INT, and the path using the return diode D7. Further, the return current also flows through the path branched to the switching element S5 side based on the resonance current of the resonance inductor Lr. On the secondary side of the transformer INT, based on the release of the electromagnetic energy accumulated in the DC reactor DCL before time t2, a reflux current flows through both the diodes D11 and D12. Note that the discharged auxiliary capacitor C1 continues to be discharged until the switching element S2 is next switched from on to off, and charging is started based on the switching element S2 being turned off.

  At “time t3”, the switching element S1 is turned off. Since the auxiliary capacitor C1 is already discharged at time t2 when the switching element S1 is turned off, the switching element S1 can be turned off with zero voltage (the potential difference between the terminals is zero), and the switching loss is reduced. Also, based on this off, the return current flows through the path using the return diode D2 based on the release of the electromagnetic energy stored in the series inductor Ls, and the switching is performed based on the release of the electromagnetic energy stored in the resonant inductor Lr. The reflux current continues to flow through the path branched to the element S5 side. Then, charging of the auxiliary capacitor C2 is started based on both of these return currents that are larger than the current value in the case where only the primary coil side of the transformer INT flows. Thereby, the charging speed of the auxiliary capacitor C2 is increased, and the charging time of the auxiliary capacitor C2 is shortened. Therefore, the auxiliary capacitor C2 is quickly charged in a short time before the switching elements S2 and S4 are turned on. On the secondary side of the transformer INT, a return current flowing through both paths of the diodes D11 and D12 is continuously generated.

  At “time t4”, the charging of the auxiliary capacitor C2 is completed. As a result, the return current generated based on the release of the electromagnetic energy accumulated in the series inductor Ls and the resonant inductor Lr is switched to a path using the return diode D4, thereby starting the charging of the smoothing capacitor Cb. Note that, on the secondary side of the transformer INT, a reflux current still flows through both paths of the diodes D11 and D12.

  When the charging of the smoothing capacitor Cb is completed with the electromagnetic energy of the series inductor Ls and the resonant inductor Lr at “time t5”, the return current (resonant current) generated on the primary side of the transformer INT disappears.

  At “time t6”, the switching element S5 is turned off and the switching elements S2 and S4 are both turned on. In this case, since the return current (resonance current) on the primary side of the transformer INT has disappeared, the switching element S5 is turned off at zero current, and the switching loss is reduced. In addition, since the current applied to the switching elements S2 and S4 from the series inductor Ls rises slowly from zero, the switching elements S2 and S4 are turned on at zero current, and these switching losses are reduced. Further, in the switching element S4, since the voltage between the terminals of the auxiliary capacitor C2 and the smoothing capacitor Cb is the same voltage, the switching element S4 is turned on at zero voltage, which also reduces the switching loss.

  Based on the switching elements S2 and S4 being turned on, the voltage across the terminals of the smoothing capacitor Cb (auxiliary capacitor C2) is supplied to the switching element S2 of the inverter circuit 13. The output voltage from the switching element S2 is supplied to the primary side coil of the transformer INT via the series inductor Ls. Accordingly, on the secondary side of the transformer INT, a direct current is supplied from the diode D12 side of the secondary side rectifier circuit DR2. A direct current voltage for arc machining is output to the torch TH through the reactor DCL.

  At “time t7”, the switching element S6 is turned on, and thereafter, the switching elements S2, S4, S6, the auxiliary capacitor C2, and the free wheeling diode D8 perform the same operations as described above, and output the arc machining DC voltage. Has been continued.

Next, characteristic effects of the present embodiment will be described.
(1) In this embodiment, a resonance circuit 15 is provided between a connection point N2 between the switching elements S1 and S2 of the inverter circuit 13 and a connection point N1 between the auxiliary capacitors C1 and C2 of the auxiliary switching circuit 14. Yes. The resonance circuit 15 resonates for a period of time T2 before each of the switching elements S3 and S4 starting discharge of the auxiliary capacitors C1 and C2, and outputs the switching elements S1 and S2 based on the discharge currents of the auxiliary capacitors C1 and C2. A resonance current is generated such that the current (currents Is1, Is2) increases. As a result, the discharge speed of the auxiliary capacitors C1 and C2 is increased, and the discharge time of the auxiliary capacitors C1 and C2 is shortened. Therefore, the auxiliary capacitors C1 and C2 are quickly discharged in a short time, and the auxiliary capacitors C1 and C2 can be surely discharged even during light load or no load. As a result, it is possible to provide the arc machining power supply device 11 that can reduce switching loss and suppress voltage surge.

  (2) In the present embodiment, the resonance circuit 15 causes the resonance current of the auxiliary capacitors C2 and C1 on the opposite side to the auxiliary capacitors C1 and C2 that have been discharged based on the switching elements S1 and S2 to be turned off. Each is supplied as a charging current. As a result, the resonance current from the resonance circuit 15 is also used as the charging current for the auxiliary capacitors C1 and C2 on the opposite side, so that the charging speed of the auxiliary capacitors C1 and C2 is increased and the auxiliary capacitors C1 and C2 are connected. Charging time is shortened. Therefore, the auxiliary capacitors C1 and C2 are quickly charged in a short time, and the auxiliary capacitors C1 and C2 can be reliably charged even at a light load or no load.

  (3) In the present embodiment, the resonance circuit 15 includes the free-wheeling diodes D5 and D6, and the switching elements S5 and S6 that are alternately operated in a pair with the switching elements S3 and S4 are reversed to each other. The switching element S5 is arranged on both sides of Lr, and the switching element S5 is connected to the connection point N2 between the switching elements S1 and S2, and the switching element S6 is connected to the connection point N1 between the auxiliary capacitors C1 and C2. Further, the resonance circuit 15 of the present embodiment includes a series inductor Ls connected in series to the primary coil of the transformer INT. That is, the resonance circuit 15 can be simply configured by the two switching elements S5 and S6 and the inductors Lr and Ls.

  (4) In the present embodiment, the switching elements S5 and S6 of the resonance circuit 15 are turned on before the corresponding switching elements S3 and S4 are turned off, and the resonance operation by the resonance inductor Lr is performed. In other words, the fifth and sixth switching elements S5 and S6 of the resonance circuit 15 are turned on before the third and fourth switching elements S3 and S4 are turned off, so that before the auxiliary capacitors C1 and C2 start discharging. The resonance current (resonance energy) of the inductor Lr, which rises slowly, can be increased in advance, whereby the discharge of the auxiliary capacitors C1, C2 is started by turning off the third and fourth switching elements S3, S4. From that time, the discharge becomes rapid. Therefore, in the present embodiment, the discharge time of the auxiliary capacitors C1 and C2 can be further shortened.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the resonance circuit 15 is configured by the two switching elements S5 and S6 and the inductors Lr and Ls. However, the number and arrangement of the switching elements and inductors may be appropriately changed. In addition to these elements, a capacitor, a resistor, or the like may be added or replaced.

  In the above-described embodiment, the switching elements S5 and S6 of the resonance circuit 15 are turned on before the switching elements S3 and S4 are turned off to start the resonance operation. However, the switching elements S5 and S6 are turned on. It may be simultaneously with each OFF of S3 and S4. Further, before the switching elements S1 and S2 are turned off, the switching elements S5 and S6 can be turned on slightly later than the switching elements S3 and S4. Further, the switching elements S5 and S6 may be turned off at the time when the resonance current disappears, not simultaneously with the switching elements S2 and S4 being turned on.

  In the above embodiment, the resonance circuit 15 changes the resonance current of the auxiliary capacitors C2 and C1 on the opposite side to the auxiliary capacitors C1 and C2 that have been discharged based on the switching elements S1 and S2 being turned off. However, the resonance current may be generated only when the auxiliary capacitors C1 and C2 are discharged, and the resonance current may not be used as the charging current.

-In above-mentioned embodiment, although IGBT was used for each switching element S1-S6, you may comprise using switching elements other than IGBT.
In the above embodiment, the power supply device 11 for arc machining is used. However, the power supply device used for purposes other than that for arc machining, specifically, the DC conversion circuit 12, the inverter circuit 13, the auxiliary switching circuit 14, and the resonance circuit 15 are used. You may implement in the AC-AC conversion power supply device which has this. Further, the present invention may be implemented in a DC-AC conversion power supply apparatus that includes the inverter circuit 13, the auxiliary switching circuit 14, and the resonance circuit 15 without the DC conversion circuit 12.

Next, a technical idea that can be grasped from the above embodiment and another example will be added below.
(B) A half-bridge circuit using first and second switching elements, and the first and second switching elements are alternately turned on and off alternately to supply a DC voltage supplied via a pair of power supply lines. An inverter circuit that converts the AC voltage into
The first and second smoothing capacitors connected in series between the power lines, and the first and second auxiliary capacitors connected in series between the power lines between the inverter circuit, and the smoothing Auxiliary switching circuit in which each of the third and fourth switching elements that are alternately operated in pairs with the first and second switching elements is arranged on each power supply line between a capacitor and the auxiliary capacitor. And
The third and fourth switching elements are turned off before the first and second switching elements are turned off in the charged state of the corresponding first and second auxiliary capacitors, respectively, and the corresponding first and second switching elements are turned off. A power supply device configured to perform soft switching control to turn off each of the first and second switching elements after discharge of the two auxiliary capacitors,
The third and fourth switchings that are provided between the first and second switching elements and between the first and second auxiliary capacitors and that start discharge of the first and second auxiliary capacitors. A resonance circuit is provided that resonates at each element off or prior to each element off and generates a resonance current that increases the output currents of the first and second switching elements based on the discharge current of the auxiliary capacitor. Power supply.

  If comprised in this way, it has an effect similar to the said Claim 1.

It is a circuit diagram which shows the power supply device for arc processing of this embodiment. It is a wave form diagram of each place of a power supply device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... Power supply device, 12 ... DC conversion circuit, 13 ... Inverter circuit,
14 ... auxiliary switching circuit, 15 ... resonance circuit,
C1, C2 ... Auxiliary capacitors (first and second auxiliary capacitors),
Ca, Cb ... smoothing capacitors (first and second smoothing capacitors),
D5, D6 ... freewheeling diode, DR1 ... primary side rectifier circuit (rectifier circuit),
L1, L2 ... power line, Lr ... resonant inductor, M ... workpiece,
S1 to S6... Switching elements (first to sixth switching elements).

Claims (5)

A DC converter circuit having first and second smoothing capacitors connected in series between a rectifier circuit and a pair of power supply lines on its output side, and converting an input AC power source into a rectified and smoothed DC voltage;
A half-bridge circuit using first and second switching elements, the first and second switching elements are alternately turned on and off, and the DC voltage supplied via the power lines is changed to a predetermined AC voltage. An inverter circuit for converting to voltage,
The first and second auxiliary capacitors are connected in series between the power supply lines between the smoothing capacitor and the inverter circuit, and the first and second auxiliary capacitors are connected on the power supply lines between the smoothing capacitor and the auxiliary capacitor. An auxiliary switching circuit in which each of the third and fourth switching elements that are alternately operated in pairs with the first and second switching elements is disposed;
The third and fourth switching elements are turned off before the first and second switching elements are turned off in the charged state of the corresponding first and second auxiliary capacitors, respectively, and the corresponding first and second switching elements are turned off. A power supply device configured to perform soft switching control to turn off each of the first and second switching elements after discharge of the two auxiliary capacitors,
The third and fourth switchings that are provided between the first and second switching elements and between the first and second auxiliary capacitors and that start discharge of the first and second auxiliary capacitors. A resonance circuit is provided that resonates at each element off or prior to each element off and generates a resonance current that increases the output currents of the first and second switching elements based on the discharge current of the auxiliary capacitor. Power supply. The power supply device according to claim 1,
The resonant circuit supplies the resonant current as charging currents for the first and second auxiliary capacitors in the opposite set based on each turn-off of the first and second switching elements, respectively. Power supply. The power supply device according to claim 1 or 2,
The resonant circuit includes fifth and sixth switching elements that have a freewheeling diode and are alternately operated in pairs with the third and fourth switching elements, and a resonant inductor. The fifth and sixth switching elements are arranged in opposite directions on both sides of the first and second switching elements, one of which is connected between the first and second switching elements and the other is connected between the first and second auxiliary capacitors. A power supply device characterized by being configured. The power supply device according to claim 3,
The power supply apparatus according to claim 5, wherein the fifth and sixth switching elements are turned on prior to turning off the corresponding third and fourth switching elements.   An arc machining power supply device configured to generate an arc machining voltage for performing arc machining of a workpiece using the power supply device according to any one of claims 1 to 4.

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