JP2009050109A - Power supply unit, and power supply unit for arc machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a power supply unit capable of coping with two input voltages, with a chopper configuration using a small reactor for on/off controlling switching elements without elevating the frequency thereof. <P>SOLUTION: In the power supply unit, in the case of a 200V system input of the half of a 400V system input, the switching elements TR1, TR2 are on/off controlled at the switching frequency same as that at the time of the 400V system input, by shifting phases by 180° from each other so as to successively generate a turning-on time for turning on the switching elements TR1, TR2 simultaneously, then only the switching element TR2, then the switching elements TR1, TR2 simultaneously, and then only the switching element TR1. This causes the energy accumulation related to the reactor La and discharge cycle to be doubled, generating the DC voltage boosted up to a prescribed voltage value similarly at the time of 400V system input. Furthermore, the energy accumulated in the reactor La at a time can be reduced to use a small reactor La. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power supply apparatus including a DC conversion circuit that converts an input AC power source into a DC voltage, and a chopper circuit that adjusts the DC voltage to a predetermined voltage value.

  The power supply device used for arc machines, etc. consists of a DC converter circuit that rectifies commercial power supply (three-phase AC power supply) with a rectifier circuit and converts it into a DC voltage smoothed with a smoothing capacitor, and a bridge circuit of switching elements. And an inverter circuit for AC conversion. In the inverter circuit, a predetermined combination of switching elements are controlled to be turned on and off in synchronization with each other, and a DC voltage from the DC conversion circuit is converted into a predetermined high-frequency AC voltage. Then, a predetermined high-frequency AC voltage from the inverter circuit is further converted into a machining DC voltage suitable for arc machining such as arc welding or arc cutting.

  As a DC conversion circuit used for the above-described power supply device or the like, there is a configuration as shown in Patent Document 1, for example, and this circuit is provided with a boost chopper circuit. The step-up chopper circuit includes a DC reactor and a switching element. The DC reactor is connected to one power supply line on the output side of the rectifier circuit, and the switching element is connected between power supply lines subsequent to the DC reactor. In addition, a diode for preventing discharge of the smoothing capacitor when the switching element is on is used, and the diode is connected on a power supply line between the switching element and the smoothing capacitor.

Then, the switching element is turned on and off, and the reactor energy accumulated at the time of turning on is discharged to the smoothing capacitor at the time of turning off, whereby the voltage across the capacitor, that is, the output DC voltage is boosted to a predetermined voltage value. By adjusting the on / off duty of this switching element, the DC voltage can be kept constant even if the input voltage fluctuates.
JP-A-3-78469

  By the way, the voltage value of the commercial power supply to be input has a 200 V system (200 to 240 V) region and a high voltage 400 V system (380 to 480 V) region worldwide. Therefore, there has been a demand for a configuration in which both of the two voltage values can be operated.

  In response to this requirement, a DC conversion circuit using a chopper circuit as shown in Patent Document 1 is applicable. As one countermeasure, when a 200V system is input, the energy stored in the DC reactor of the chopper circuit at a time is 400V. Although it is possible to cope with it by making it twice that at the time of input, it is necessary to select a large reactor that does not saturate.

  As another countermeasure, the energy per unit time accumulated in the reactor can be doubled even when the switching element of the chopper circuit is turned on / off at a switching frequency twice as high as that at the time of 400V input at the time of 200V input. In addition, since the energy stored in the reactor at one time is half of the above (equivalent to the 400V system input), there is an advantage that it can be handled with a small reactor.

  However, even in this case, it is necessary to select a switching element having a large capacity because the switching loss at the switching element increases when the switching frequency is doubled. Thus, the countermeasures associated with the increase in size of the switching element and the reactor described above are not preferable because they cause various problems.

  The present invention has been made in order to solve the above-described problems. The object of the present invention is to use two different types of choppers that use a small reactor and perform on / off control without increasing the switching frequency of the switching element. An object of the present invention is to provide a power supply device and an arc machining power supply device that can cope with an input voltage.

  In order to solve the above-mentioned problem, the invention described in claim 1 includes a rectifier circuit and a smoothing capacitor connected between a pair of power supply lines on its output side, and a DC voltage obtained by rectifying and smoothing an input AC power supply A direct current conversion circuit for converting to a reactor, a reactor provided on an input side or an output side of the rectifier circuit, a switching element connected between the power supply lines to store and release energy related to the reactor, and to the switching element side The chopper circuit comprising a discharge prevention element for preventing the discharge of the smoothing capacitor, and the direct current boosted to a predetermined voltage value by controlling the on / off of the switching element to store and release the energy related to the reactor. Power supply having a chopper control circuit that generates a voltage and adjusts the voltage value by changing the duty of the on / off control The smoothing capacitor is composed of first and second smoothing capacitors connected in series between the power supply lines, and the switching element is connected in series between the power supply lines. A second switching element, and a connection point between the first and second smoothing capacitors and a connection point between the first and second switching elements are connected to each other, and the chopper control is performed. When the input AC power supply has a first voltage value, the circuit controls on and off of the first and second switching elements simultaneously, and the input AC power supply is about half of the first voltage value. In the case of the second voltage value, a first time during which the first and second switching elements are simultaneously turned on and a second time during which any one of the first and second switching elements is turned on. And a third time for simultaneously turning on the first and second switching elements and a fourth time for turning on the other of the first and second switching elements are continuously generated. The gist is to perform on / off control with the same period as that of the first voltage value and with a phase difference of 180 °.

  In the present invention, when the input AC power supply has the first voltage value, the chopper control circuit controls on and off of the first and second switching elements simultaneously. That is, when the first and second switching elements are simultaneously turned on, energy is accumulated in the reactor, and when the first and second switching elements are simultaneously turned off, the first and second switching elements are released due to the release of the energy accumulated in the reactor. The voltage across the second smoothing capacitor is boosted, and a boosted DC voltage having a predetermined voltage value is generated. In addition, when the input AC power supply has a second voltage value that is approximately half of the first voltage value, the chopper control circuit performs the first time, the first time, and the second time when the first switching element and the second switching element are simultaneously turned on. A second time for turning on one of the two switching elements, a third time for turning on the first and second switching elements simultaneously, and a fourth time for turning on the other of the first and second switching elements. On / off control is performed in the same cycle as the case of the first voltage values that are 180 ° out of phase so that the time of 生 じ る is continuously generated. That is, energy is stored in the reactor at the first and third times when the first and second switching elements are simultaneously turned on. On the other hand, in the second time when either one of the first and second switching elements is turned on, the accumulated reactor energy is released to one of the first and second smoothing capacitors, In the fourth time when either one of the first and second switching elements is turned on, the stored reactor energy is released to one of the first and second smoothing capacitors. In this way, the energy storage / release cycle related to the reactor is doubled by combining the respective on / off timings while keeping the switching frequencies of the first and second switching elements the same, and when the first voltage value is input. In the same manner as described above, a DC voltage boosted to a predetermined voltage value is generated. In addition, in this case, since the energy stored in the reactor at a time can be kept small, a small reactor can be used.

  According to a second aspect of the present invention, in the power supply device according to the first aspect, the chopper includes a voltage determination unit that determines whether the input AC power source is the first voltage value or the second voltage value. The gist of the control circuit is to switch on / off control of the first and second switching elements based on the determination of the voltage determination means.

  In the present invention, voltage determining means for determining whether the input AC power supply has one of the first voltage value and the second voltage value is provided, and the chopper control circuit is configured to determine the first and second voltages based on the determination by the voltage determining means. The on / off control of the switching element 2 is switched. That is, since the chopper control circuit automatically switches the control based on the determination by the voltage determination means, it can easily and reliably cope with each voltage value of the input AC power supply.

  The gist of a third aspect of the present invention is the power supply device according to the first or second aspect, wherein the reactor is a direct current reactor provided on the output side of the rectifier circuit.

In the present invention, the chopper circuit is configured using a single DC reactor provided on the output side of the rectifier circuit, and therefore the chopper circuit can be configured simply.
According to a fourth aspect of the present invention, in the power supply device according to the first or second aspect, the input AC power source is a three-phase AC power source, and the reactor is provided in each phase on the input side of the rectifier circuit. The gist is that it is an AC reactor.

  In this invention, since the chopper circuit is configured by using the AC reactor provided for each phase on the input side of the rectifier circuit, it is possible to use a smaller one than the DC reactor provided on the output side of the rectifier circuit. It is.

  The invention according to claim 5 further includes an inverter circuit for converting the DC voltage generated by the DC converter circuit into a predetermined AC voltage with respect to the power supply device according to any one of claims 1 to 4. The gist is that it is configured.

  In this invention, since the power supply device according to any one of claims 1 to 4 further includes an inverter circuit, it is possible to provide a power supply device with an inverter that can obtain the same effects as the above-mentioned claims.

The invention described in claim 6 is 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 claim 5.
In the present invention, since the power supply device according to claim 5 is used, it is possible to provide an arc machining power supply device that can obtain the same effects as those of the above claims.

  According to the present invention, there is provided a power supply device and an arc machining power supply device that can cope with two different input voltages while using a small reactor and having a chopper configuration that performs on / off control without increasing the switching frequency of the switching element. can do.

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 a DC voltage for arc machining 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. An arc machining power supply device 11 used for such an arc machine 10 includes a DC conversion circuit 12 that converts an input commercial power supply (three-phase AC voltage) into a DC voltage, and converts the DC voltage into a predetermined high-frequency AC voltage. An inverter circuit INV for conversion, and further converts the high-frequency AC voltage from the inverter circuit INV into a processing DC voltage.

  The DC conversion circuit 12 is configured by a bridge circuit using six diodes D1 to D6, and performs primary wave rectification circuit DR1 for full-wave rectification of a three-phase input AC power supply, and first and second rectifier circuits on the output side of the rectification circuit DR1. The first and second smoothing capacitors C1 and C2 connected in series between the second power supply lines L1 and L2 and smoothing the output voltage of the rectifier circuit DR1 generate a DC voltage from the input AC power supply. . The first and second smoothing capacitors C1 and C2 have the same capacity.

  Further, the DC conversion circuit 12 includes a boost chopper circuit 13 between the rectifier circuit DR1 and the smoothing capacitors C1 and C2. The step-up chopper circuit 13 includes a DC reactor La, first and second switching elements TR1 and TR2 made of IGBT, and diodes D7 and D8. The DC reactor La is arranged on the first power supply line L1 on the output side of the rectifier circuit DR1, and the first and second switching elements TR1 and TR2 are connected between the power supply lines L1 and L2 at the subsequent stage of the DC reactor La. Connected in series. A connection point between the emitter of the first switching element TR1 and the collector of the second switching element TR2 and a connection point between the first and second smoothing capacitors C1 and C2 are connected to each other. In addition, a diode D7 having a cathode side directed to the smoothing capacitor C1 is disposed on the power supply line L1 between the first switching element TR1 and the first smoothing capacitor C1, and the second switching element TR2 and the second switching element TR2 A diode D8 having a cathode side directed to the switching element TR2 is disposed on the power supply line L2 between the first and second smoothing capacitors C2. The diodes D7 and D8 are provided as discharge prevention elements for the smoothing capacitors C1 and C2.

  Further, in the DC conversion circuit 12, a first voltage detection circuit IV1 for detecting a DC voltage on the rear stage side of the chopper DC reactor La is connected between the power supply lines L1 and L2. The first voltage detection circuit IV1 outputs the detected DC voltage as the first voltage detection signal Iv1 to the chopper control circuit CR. Further, a second voltage detection circuit IV2 for detecting a DC voltage on the subsequent stage side is connected between the power supply lines L1 and L2 on the subsequent stage side of the smoothing capacitors C1 and C2. The second voltage detection circuit IV2 outputs the detected DC voltage as the second voltage detection signal Iv2 to the chopper control circuit CR. The chopper control circuit CR determines whether the input AC power supply is 200V system or 400V system based on the first voltage detection signal Iv1, and determines the DC voltage supplied to the inverter circuit INV based on the second voltage detection signal Iv2. The voltage value is detected.

  The chopper control circuit CR outputs control signals Tr1 and Tr2 to the first and second switching elements TR1 and TR2, and performs on / off control of the switching elements TR1 and TR2 according to the voltage value of the input AC power supply. The chopper control circuit CR is independent of the output control circuit SC described later, but may be linked. The chopper control circuit CR controls the DC voltage supplied to the inverter circuit INV to be a constant voltage value regardless of whether the input AC power supply is 200V system or 400V system. Details of the control of the chopper control circuit CR will be described later.

  The inverter circuit INV is connected to the power supply lines L1 and L2, and is configured by a bridge circuit using four switching elements (not shown) made of IGBT. These switching elements are alternately turned on and off based on a control signal Sc1 from the input output control circuit SC, and convert the DC voltage from the DC conversion circuit 12 into a predetermined high-frequency AC voltage to transform the transformer INT. To the primary coil.

  The high-frequency AC voltage generated by the inverter circuit INV is supplied to the primary coil of the transformer INT, and the secondary side of the transformer INT is provided with a secondary rectifier circuit DR2 and a DC reactor DCL. The secondary rectifier circuit DR2 and the DC reactor DCL convert the high-frequency AC voltage from the inverter circuit INV into a DC voltage for arc machining, and this arc machining voltage is supplied to the torch TH via the output line L3 on the DC reactor DCL side. Is output. On the other hand, the output line L4 is connected to the workpiece M, and an arc is generated from the torch TH toward the workpiece M based on the supply of the arc machining voltage.

  Further, an output current detection circuit ID for detecting an actual output current value is connected to the output line L4. The output current detection circuit ID outputs the detected output current value to the comparison operation circuit ER as an output current detection signal Id. The comparison operation circuit ER outputs the output current detection signal Id and the output from the output current setting device IR. The current setting signal Ir is compared. Incidentally, in the output current setting device IR, the output current value is set by a human operation or the like so as to obtain an output current value corresponding to the workpiece M to be arced, and an output current setting signal corresponding to the setting is set. Ir is output to the comparison operation circuit ER. The comparison operation circuit ER compares the output current detection signal Id with the output current setting signal Ir, that is, outputs the difference between the output current value and the set value to the output control circuit SC as a comparison operation signal Er. Used for feedback control in the output control circuit SC.

Next, the control of the chopper control circuit CR will be described with reference to FIG. 2 when the input AC power source is a 400V system and FIG. 3 when the input AC power source is a 200V system.
The chopper control circuit CR first determines whether the input AC power source is a 200V system or a 400V system based on the input of the voltage detection signal Iv1 from the first voltage detection circuit IV1, and based on the detection of this input voltage, the 200V system input Select whether to use chopper control for time or chopper control for 400V input. The chopper control circuit CR is configured so that the DC voltage generated by the DC conversion circuit 12 in each chopper control is constant at a predetermined voltage value based on the input of the voltage detection signal Iv2 from the second voltage detection circuit IV2. I have control.

[For 400V input]
As shown in FIG. 2, the chopper control circuit CR has a duty cycle in which the on-time t1 (off-time t2) in the cycle T1 is adjusted so that the DC voltage supplied to the inverter circuit INV is constant at a predetermined voltage value. The first and second switching elements TR1 and TR2 are turned on / off simultaneously.

  That is, at the time t1 when the switching elements TR1 and TR2 are simultaneously turned on, the power supply lines L1 and L2 are short-circuited by the switching elements TR1 and TR2, so that the voltage of the DC reactor La for chopper rises and the current also increases. As a result, energy is accumulated in the DC reactor La. When the switching elements TR1 and TR2 are turned on, the discharge of the first and second smoothing capacitors C1 and C2 in the subsequent stage is prevented by the diodes D7 and D8. On the other hand, at the time t2 when the switching elements TR1 and TR2 are simultaneously turned off, the power lines L1 and L2 are disconnected, so that the current decreases as the voltage of the DC reactor La decreases, and the energy accumulated in the DC reactor La is released. The As a result, the first and second smoothing capacitors C1 and C2 in the subsequent stage are charged by the output voltage of the rectifier circuit DR1 and also charged by the energy accumulated in the DC reactor La, and the first and second smoothing capacitors The voltage between both ends of C1 and C2 is boosted to the output voltage of the rectifier circuit DR1 or higher.

  The switching elements TR1 and TR2 are repeatedly turned on and off at times t1 and t2, thereby boosting the voltage across the first and second smoothing capacitors C1 and C2, that is, the DC voltage supplied to the inverter circuit INV. It is generated as a constant predetermined voltage value. Incidentally, as the on-time t1 of the switching elements TR1 and TR2 is longer, the accumulation of energy of the DC reactor La is larger and the voltage between both ends of the first and second smoothing capacitors C1 and C2 is increased. The length of the on-time t1 during T1 is adjusted, and the DC voltage supplied to the inverter circuit INV is controlled to be a predetermined voltage value.

[In case of 200V input]
As shown in FIG. 3, the chopper control circuit CR has a first duty cycle with the duty adjusted for the on-time (off-time) in the cycle T1 so that the DC voltage supplied to the inverter circuit INV is constant at a predetermined voltage value. The switching element TR1 is turned on and off, and the second switching element TR2 is turned on and off with the same duty that is 180 degrees out of phase with the first switching element TR1. That is, the chopper control circuit CR combines the respective on / off timings with the same switching frequency, thereby simultaneously turning on the first and second switching elements TR1 and TR2, and then the first switching element. A second time t2 ′ for turning off TR1 and turning on the second switching element TR2, then a third time t3 ′ for turning on the first and second switching elements TR1 and TR2 simultaneously, and then the first switching element TR1 ON / OFF control is performed so that the fourth time t4 ′ during which the second switching element TR2 is turned off and the second switching element TR2 is continuously generated occurs.

  As described above, at the time t1 ′ and the time t3 ′ when the switching elements TR1 and TR2 are turned on at the same time, the power lines L1 and L2 are short-circuited by the switching elements TR1 and TR2. Therefore, the energy is supplied to the DC reactor La for chopper. Is accumulated. On the other hand, at time t2 ′ when the first switching element TR1 is turned off and the second switching element TR2 is turned on, the energy accumulated in the DC reactor La is released to the first smoothing capacitor C1 and the smoothing capacitor C1. At time t4 ′ when the inter-terminal voltage is boosted and the first switching element TR1 is turned on and the second switching element TR2 is turned off, the energy accumulated in the DC reactor La is released to the second smoothing capacitor C2. The voltage across the terminals of the smoothing capacitor C2 is boosted.

  The switching elements TR1 and TR2 are repeatedly turned on and off at times t1 ′ to t4 ′, so that the energy storage / release cycle related to the DC reactor La is doubled during the same period T1 as when the 400V system is input. The voltage across the first and second smoothing capacitors C1 and C2, that is, the DC voltage supplied to the inverter circuit INV, is generated as a constant voltage value boosted in the same manner as in the 400V system input. Incidentally, even at the time of the 200V input, the longer the simultaneous ON times t1 ′ and t3 ′ of the switching elements TR1 and TR2, the greater the accumulation of energy of the DC reactor La, and the both ends of the first and second smoothing capacitors C1 and C2. Since the voltage rises, the chopper control circuit CR adjusts the lengths of the on-times t1 ′ and t3 ′ during the period T1, that is, adjusts the on-times of the individual switching elements TR1 and TR2, and supplies the DC voltage to the inverter circuit INV. Is controlled to be constant at a predetermined voltage value.

Next, characteristic effects of the present embodiment will be described.
(1) In the power supply device 11 of the present embodiment, the first and second switching elements TR1 and TR2 are simultaneously turned on and off under the control of the chopper control circuit CR when the first voltage value is a 400V system input. That is, when the first and second switching elements TR1 and TR2 are simultaneously turned on, energy is accumulated in the reactor La, and when the first and second switching elements TR1 and TR2 are simultaneously turned off, the energy is accumulated in the reactor La. Due to the release of the energy, the voltage across the first and second smoothing capacitors C1 and C2 is boosted, and a boosted DC voltage having a predetermined voltage value is generated.

  In the case of a 200V system input that is the second voltage value, the first time t1 ′ for simultaneously turning on the first and second switching elements TR1 and TR2, and the second time for turning on the second switching element TR2. t2 ′, the third time t3 ′ for simultaneously turning on the first and second switching elements TR1 and TR2, and the fourth time t4 ′ for turning on the first switching element TR1 are successively generated. The elements TR1 and TR2 are turned on and off with a phase shift of 180 ° with the same period T1 as when the 400V system is input. That is, energy is accumulated in the reactor La at times t1 'and t3' when the first and second switching elements TR1 and TR2 are simultaneously turned on. On the other hand, at the time t2 ′ when the second switching element TR2 is turned on, the accumulated energy of the reactor La is released to the first smoothing capacitor C1, and the time t4 when the first switching element TR1 is turned on. In ', the accumulated energy of the reactor La is discharged to the second smoothing capacitor C2.

  In this way, the energy storage / release cycle related to the reactor La is doubled by combining the respective on / off timings with the same switching frequency of the first and second switching elements TR1 and TR2, and when the 400V system is input. In the same manner as described above, a DC voltage boosted to a predetermined voltage value is generated. In addition, in this case, since the energy stored in the reactor La at a time can be kept small, it is possible to use a small reactor La. Thus, in the present embodiment, it is possible to cope with two different input voltages while using a small reactor La and performing on / off control without increasing the switching frequency of the switching elements TR1 and TR2.

  (2) In this embodiment, the chopper control circuit CR determines whether the input AC power supply is 200V system or 400V system based on the voltage detection by the first voltage detection circuit IV1 (voltage determination means), and the chopper control circuit CR Switches on / off control of the first and second switching elements TR1, TR2 based on the voltage determination. That is, since the chopper control circuit CR automatically switches the control based on the voltage determination based on the detection by the first voltage detection circuit IV1, it can easily and surely correspond to each voltage value of the input AC power supply.

  (3) In the present embodiment, since the chopper circuit 13 is configured using the DC reactor La provided on the output side of the rectifier circuit DR1, the chopper circuit 13 can be configured simply.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the chopper circuit 13 is configured by using one DC reactor La on the output side of the rectifier circuit DR1, but the present invention is not limited to this. For example, as shown in FIG. 4, the rectifier circuit DR1 The chopper circuit 13 may be configured by providing AC reactors Lu, Lv, and Lw for each phase on the input side. In this case, the switching elements TR1 and TR2 can be handled by the same control. In this way, it is possible to use a smaller one than the DC reactor La.

  In the above embodiment, the diodes D7 and D8 are provided on the power supply lines L1 and L2 as the discharge preventing elements of the smoothing capacitors C1 and C2. Good.

  In the above embodiment, the chopper control circuit CR determines whether the input AC power supply is 200V system or 400V system by detecting the voltage in the first voltage detection circuit IV1, and the control is automatically switched. Or the like, and the control by the chopper control circuit CR may be artificially switched.

  In the above embodiment, the IGBT is used for each of the switching elements TR1 and TR2 of the chopper circuit 13. However, a switching element other than the IGBT may be used. Note that the switching element of the inverter circuit INV may also be configured using a switching element other than the IGBT.

  In the above embodiment, the arc machining power supply device 11 is implemented, but a power supply device used for purposes other than arc machining, for example, an AC-AC conversion power supply device using a DC conversion circuit 12 and an inverter circuit INV, or a DC conversion You may implement in the AC-DC conversion power supply device which uses the circuit 12. FIG. Even if it does in this way, the effect similar to the said embodiment is acquired.

It is a circuit diagram which shows the power supply apparatus for arc processing in this embodiment. It is a wave form diagram at the time of the 400V type | system | group input in this embodiment. It is a wave form diagram at the time of 200V type | system | group input in this embodiment. It is a circuit diagram which shows the power supply device for arc processing in another example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Power supply device, 12 ... DC converter circuit, 13 ... Chopper circuit, CR ... Chopper control circuit (including voltage determination means), D7, D8 ... Diode as discharge prevention element, DR1 ... Primary side rectifier circuit as rectifier circuit , INV... Inverter circuit, IV1... First voltage detection circuit constituting voltage determination means, L1, L2... Power line, La... DC reactor as reactor, Lu, Lv, Lw .. AC reactor as reactor, M. Processing object, TR1, TR2... First and second switching elements as switching elements, t1 ′ to t4 ′.

Claims (6)

A DC conversion circuit having a smoothing capacitor connected between the rectifier circuit and a pair of power supply lines on its output side, and converting the input AC power supply into a DC voltage obtained by rectifying and smoothing;
A reactor provided on the input side or output side of the rectifier circuit, a switching element connected between the power supply lines for storing and releasing energy related to the reactor, and preventing the smoothing capacitor from discharging to the switching element side A chopper circuit comprising an anti-discharge element;
The switching element is turned on / off to store and release energy related to the reactor, thereby generating the DC voltage boosted to a predetermined voltage value and changing the duty of the on / off control to adjust the voltage value A power supply device including a chopper control circuit for performing
The smoothing capacitor is composed of first and second smoothing capacitors connected in series between the power supply lines, and the switching element is a first and second switching element connected in series between the power supply lines. And further connecting the connection point between the first and second smoothing capacitors and the connection point between the first and second switching elements,
When the input AC power supply has a first voltage value, the chopper control circuit simultaneously controls on / off of the first and second switching elements, and the input AC power supply has the first voltage value. When the second voltage value is about half, the first time during which the first and second switching elements are simultaneously turned on and the second time during which any one of the first and second switching elements is turned on. And a third time for simultaneously turning on the first and second switching elements and a fourth time for turning on the other of the first and second switching elements are continuously generated. A power supply device that performs on / off control with the same period as that of the first voltage value and with a phase difference of 180 °. The power supply device according to claim 1,
Voltage determining means for determining whether the input AC power supply is one of the first and second voltage values;
The chopper control circuit switches on / off control of the first and second switching elements based on the determination by the voltage determination means. The power supply device according to claim 1 or 2,
The said reactor is a direct current | flow reactor provided in the output side of the said rectifier circuit, The power supply device characterized by the above-mentioned. The power supply device according to claim 1 or 2,
The input AC power source is a three-phase AC power source,
The said reactor is an alternating current reactor with which each phase by the side of the input of the said rectifier circuit is equipped, The power supply device characterized by the above-mentioned.   The power supply device according to any one of claims 1 to 4, further comprising an inverter circuit for converting a DC voltage generated by the DC conversion circuit into a predetermined AC voltage. Power supply.   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 claim 5.

Images