JP2008062246A - Power unit for arc machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a circuit constitution the ripple of which is small in a voltage doubler rectifier circuit. <P>SOLUTION: A power unit for arc machining is provided with a three-phase full wave rectifier circuit, a smoothing capacitor provided in parallel to the three-phase full wave rectifier circuit, an output control circuit for controlling the output of an inverter circuit, a main transformer for converting the inverter output into a voltage suitable for the arc and a secondary rectifying circuit for rectifying the converted output. Further, the power unit is provided with: a charging switching element which is provided between first to third series circuits provided between the three-phase full wave rectifier circuit and the smoothing capacitor, a first input terminal (U phase) to a third input terminal (W phase) and first to third series circuits and which supplies the charging current which is generated from the prescribed potential difference in each phase to each series circuit; and a charging control circuit for conducting the charging switching element by outputting a charging control signal when the direct-current voltage of the three-phase full wave rectifier circuit is not higher than the prescribed reference voltage and for stopping the output of the charging control signal when the direct-current voltage is equal to or higher than the reference voltage. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power supply device for arc machining in which a three-phase AC power supply can be used with either two systems having a high voltage or a low voltage that is about half that voltage.

  In the arc machining power supply device, the three-phase AC power supply has shared two power supplies of 200V or 400V, and has been dealt with by switching the turns ratio of the transformer.

  FIG. 4 is an electrical connection diagram of a conventional arc machining power supply device. In the figure, diodes D13 to D21 are primary rectification diodes that three-phase full-wave rectify a three-phase AC power source to a DC voltage. The switches SW1 to SW3 are voltage changeover switches that are linked to each other, and the smoothing capacitor C11 and the smoothing capacitor C12 are capacitors that smooth the DC voltage.

  For example, the inverter circuit INV forms a full bridge with four switching elements (not shown). The main transformer INT converts the high frequency AC voltage suitable for arc machining and outputs it, and the secondary rectifier circuit DR1 rectifies and outputs the high frequency AC voltage to a DC voltage.

  When the voltage changeover switches SW1 to SW3 shown in FIG. 4 are on the a side, for example, 200V side (low voltage side), the voltage doubler rectifier circuit is formed by the diodes D13 to D21 and the capacitors C8 to C10. . On the other hand, when the voltage changeover switch SW1 to voltage changeover switch SW3 are on the b side, for example, 400V side (high voltage side), a three-phase full-wave rectifier circuit is formed by the diodes D13 to D21.

  Next, the operation will be described using the input waveform diagram of the three-phase AC power source shown in FIG. When the voltage changeover switch SW1 to voltage changeover switch SW3 shown in FIG. 4 are on the b side, for example, 400V side (high voltage side), the circuit is a normal three-phase full-wave rectifier circuit, and the description is omitted. The operation when the changeover switch SW1 to the voltage changeover switch SW3 are on the a side and 200V side (low voltage side) will be described together with the U, V, and W phase voltage waveforms of the three-phase AC power supply.

  In the period T1 shown in FIG. 5, the U-phase potential is the highest and the V-phase potential is the lowest. Therefore, the capacitor C8 is charged through the diode D14 by the voltage between UV. At this time, the input terminal U, the voltage changeover switch SW3, the capacitor C10, the diode D19, the output terminal 1, the smoothing capacitor C11, the smoothing capacitor C12, the output terminal 2, the diode D18, the first terminal, are shown between the output terminals 1 and 2 shown in the figure. A voltage is applied through the path of the two input terminals (V phase).

  At this time, the diode D13 and the diode D16 are reverse-biased by the capacitor C10 and the U-phase or V-phase potential and do not conduct. Here, the capacitor C10 is charged in the period of T5 before this, and the polarity is the same as the voltage between UV with the connection point of the diode D19 and the diode D20 being positive, so that it is between the output terminals 1 and 2. The sum of these voltages is applied.

  In the period T2, the terminal voltage of the capacitor C8 is charged up to the peak value of the voltage between the UVs, so that this state is maintained without being charged any more. On the other hand, since the potential of the W phase is the lowest between the output terminals 1 and 2, the sum of the voltage between WUs and the terminal voltage of the capacitor C10 is output through the diode D21.

  During the period T3, the V-phase potential is the highest and the W-phase potential is the lowest, so that the capacitor C9 is charged by the voltage between VW, and at the same time, the sum of the voltage of the capacitor C8 and the voltage between VW is the output terminals 1, 2 Output in between.

  During the period T4, charging of the capacitor C9 is stopped, and the sum of the terminal voltage of the capacitor C9 and the voltage between VU is output between the output terminals 1 and 2.

  During the period T5, the capacitor C10 is charged by the voltage between the WUs, and the sum of the terminal voltage of the capacitor C9 and the voltage between the WUs is output between the output terminals 1 and 2.

  During the period T6, the charging of the capacitor C10 is stopped, and the sum of the terminal voltage of the capacitor C9 and the voltage between WV is output between the output terminals 1 and 2.

  In each period in which the above-described T1 to T6 are repeated, the terminal voltage of each capacitor is always the same polarity, and the output terminal 1 side has a positive polarity. Double the output voltage is supplied. (For example, Patent Document 1)

JP-A-5-96372

  In the conventional arc machining power supply device, since the three-phase AC power supply shares two power supplies of 200V or 400V, the voltage selector switches SW1 to SW3 shown in FIG. 4 are set to the a side, for example, the 200V side (low voltage side). In this case, a voltage doubler rectifier circuit is formed by nine diodes and three capacitors, and this three-phase full-wave rectifier circuit generates a DC voltage having a pulsation obtained by three-phase full-wave rectification of 200 V of a three-phase AC power source. Boost the output twice and output. On the other hand, when the voltage change-over switches SW1 to SW3 are on the b side, for example, 400V side (high voltage side), a three-phase full-wave rectifier circuit is formed by nine diodes. In this way, it is possible to share two power sources by outputting three-phase full-wave rectification of 400V.

  However, in the conventional voltage doubler rectifier circuit, when the three-phase AC power supply is a 400V system, the ripple value of the DC voltage subjected to three-phase full-wave rectification does not change, and the life of the smoothing capacitor is not affected. However, when the three-phase AC power supply is a 200V system, the DC voltage having pulsation obtained by three-phase full-wave rectification is boosted twice, so that the ripple value of the DC voltage also increases according to the boost. As the ripple value increases, the lifetimes of the smoothing capacitor and the boost capacitor are shortened. Normally, the life of smoothing capacitors and boost capacitors is about 5 to 7 years. The life of the smoothing capacitors and boost capacitors is the shortest of all the parts used in the welding machine. . Therefore, when the three-phase AC power supply is a 200V system, it is necessary to increase the capacity in order to extend the life of the smoothing capacitor and the boost capacitor in response to the increase in the ripple value. The outer dimensions of the capacitor will increase, leading to an increase in the size of the welder.

  Therefore, an object of the present invention is to provide an arc machining power supply device that can solve the above-described problems.

  In order to solve the above-mentioned problem, the first invention comprises a three-phase bridge diode that rectifies a three-phase AC power source input from the first to third input terminals and outputs a pulsating DC voltage. A three-phase full-wave rectifier circuit; a smoothing capacitor provided in parallel to the three-phase full-wave rectifier circuit for smoothing the pulsating DC voltage; an inverter circuit for converting the DC voltage to a high-frequency AC voltage; An arc provided with an output control circuit for controlling output, a main transformer for converting to a high-frequency AC voltage suitable for arc machining, and a secondary rectifier circuit for rectifying the output of the main transformer to output a DC voltage In the processing power supply apparatus, the first to sixth boost capacitors have the same capacity, and the first boost capacitor and the second boost capacitor are connected in series to form the three-phase full-wave rectifier circuit. Between the three-phase full-wave rectifier circuit and the smoothing capacitor in series with the first series circuit provided between the three-phase full-wave rectifier circuit and the smoothing capacitor. A third series circuit provided between the three-phase full-wave rectifier circuit and the smoothing capacitor with the second series circuit provided, the fifth boost capacitor and the sixth boost capacitor in series. A first charging circuit that is provided between the circuit, the first input terminal, and a midpoint of the first series circuit, and that supplies a charging current generated by a predetermined potential difference between the phases to the first series circuit. Switching element, second charging switching element, and first charging diode provided in parallel to the first charging switching element and second charging switching element in parallel in the reverse direction. A charging current generated by a predetermined potential difference between each phase provided between the second charging diode, the second input terminal and the middle point of the second series circuit is supplied to the second series circuit. The third charging switching element and the fourth charging switching element to be supplied, and the third charging diode and the fourth charging switching element provided in parallel in the reverse direction to the third charging switching element are reversed. A fourth charging diode provided in parallel in the direction, and a charging current generated by a predetermined potential difference between each phase provided between the third input terminal and the middle point of the third series circuit. The fifth charging switching element and the sixth charging switching element to be supplied to the three series circuits, the fifth charging diode and the sixth charging diode provided in parallel in the reverse direction to the fifth charging switching element. When the DC voltage of the sixth charging diode and the three-phase full-wave rectifier circuit is less than or equal to a predetermined reference voltage value, the maximum conduction ratio shifted from each other by a half cycle is obtained. The first charging control signal and the second charging control signal for the same time are repeatedly output, and the first charging switching element, the third charging switching element, and the fifth charging control signal are output according to the first charging control signal. The charging switching element is turned on, and the second charging switching element, the fourth charging switching element, and the sixth charging switching element are turned on in response to a second charge control signal, and the DC voltage is When the voltage is equal to or higher than a reference voltage value, the output of the first charge control signal and the second charge control signal is stopped, and the first to sixth charging switching elements are shut off. And a charge control circuit, is arc machining power supply apparatus characterized by comprising.

  The second invention is characterized in that the charge control circuit compares the DC voltage with the reference voltage after a predetermined time from when the three-phase AC power is turned on. It is a power supply device for arc machining.

  According to the first aspect of the present invention, the voltage doubler booster circuit is formed from the first charging switching element to the sixth charging switching element and the first boosting capacitor to the sixth boosting capacitor. Then, the first charging switching element, the third charging switching element, the fifth charging switching element, the second charging switching element, the fourth charging switching element, and the sixth charging switching element are provided. Conductive alternately at a predetermined high frequency (for example, 20 kHz above the audible range), and the first to sixth boost capacitors are charged at high speed to boost the DC voltage of the three-phase full-wave rectifier circuit to a double voltage. Therefore, the ripple of the boosted DC voltage greatly decreases as the frequency increases, and the life of the smoothing capacitor and each boost capacitor is extended by the reduction of the ripple value.

  According to the second aspect of the invention, the charging control circuit is configured such that the rectified DC voltage and the reference are supplied when a predetermined time elapses after the three-phase AC power is turned on and the rectification of the three-phase AC power is started. Since the voltage is compared, it is possible to automatically and accurately determine whether the input voltage of the three-phase AC power supply is 200V or 400V.

  FIG. 1 shows an arc machining power supply apparatus according to Embodiment 1 of the present invention. In the figure, components having the same reference numerals as those in the electrical connection diagram of the arc machining power supply device of the prior art shown in FIG. 4 perform the same operations, and thus description thereof will be omitted. Only components having different reference numerals will be described.

  The first diode D1 to the sixth diode D6 shown in FIG. 1 form a three-phase full-wave rectifier circuit composed of a three-phase bridge diode. The input voltage detection circuit IV detects a DC voltage that has undergone three-phase full-wave rectification and outputs it as an input voltage detection signal Iv.

  The first boost capacitor C1 to the sixth boost capacitor C6 shown in FIG. 1 have the same capacity, and the first boost capacitor C1 and the second boost capacitor C2 are provided in series to form a first series circuit. A third booster capacitor C3 and a fourth booster capacitor C4 are provided in series to form a second series circuit, and a fifth booster capacitor C5 and a sixth booster capacitor C6 are provided in series to provide a third series circuit. Form.

  The first charging switching element TR1 and the second charging switching element TR2 are a first series formed of a first input terminal (U phase), a first boost capacitor C1, and a second boost capacitor C2. The first charging diode D7 is provided in parallel with the first charging switching element TR1 in parallel in the reverse direction, and the second charging diode D8 is connected to the second charging diode. The first boost capacitor C1 and the second boost capacitor C2 are connected to the switching element TR2 in parallel in the opposite direction, and the current generated by the potential difference of each phase is charged.

  The third charging switching element TR3 and the fourth charging switching element TR4 are a second series formed of a second input terminal (V phase), a third boost capacitor C3, and a fourth boost capacitor C4. The third charging diode D9 is connected in parallel with the third charging switching element TR3 in the reverse direction, and the fourth charging diode D10 is connected to the fourth charging point. The third boost capacitor C3 and the fourth boost capacitor C4 are connected to the switching element TR4 in parallel in the opposite direction, and the current generated by the potential difference of each phase is charged.

  The fifth charging switching element TR5 and the sixth charging switching element TR6 are a third series formed by a third input terminal (W phase), a fifth boost capacitor C5, and a sixth boost capacitor C6. The fifth charging diode D11 is provided in parallel with the fifth charging switching element TR5 in parallel with the fifth charging diode D11, and the sixth charging diode D12 is connected to the middle point of the circuit. The fifth switching capacitor C5 and the sixth boosting capacitor C6 are connected to the switching element TR6 in parallel in the opposite direction, and the current generated by the potential difference of each phase is charged.

  Although the inverter circuit INV uses a full bridge circuit formed by four switching elements, a half bridge circuit or a forward circuit may be used.

  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 and the output current detection signal Id, and outputs the comparison operation signal Er. The output control circuit SC performs PWM control that modulates the pulse width with a constant pulse frequency, and sets the pulse widths of the first output control signal Sc1 and the second output control signal Sc2 according to the value of the comparison calculation signal Er. Control.

  FIG. 2 is a detailed diagram of the charge control circuit CR. The first comparison circuit CP1, the second comparison circuit CP2, the input reference setting circuit VR1, the reference voltage setting circuit VR2, the first AND circuit AD1, and the second AND circuit. The circuit AD2, the time limit circuit TI, the inverting circuit IN, and the switching element driving circuit SD are formed. When the value of the input voltage detection signal Iv detected by the input voltage detection circuit IV is smaller than a predetermined reference voltage setting value Vr2 set by the reference voltage setting circuit VR2, the charge control circuit CR It is determined that the phase AC power supply is a 200V system, and the switching element driving circuit SD starts to operate, and the first charging control signal Tc1 and the second charging control signal of the same time with the maximum conduction ratio shifted from each other by a half cycle. Tc2 is output.

  Next, with reference to the input waveform diagram of the three-phase AC power source shown in FIG. 5, the boosting operation of the present invention will be described when the three-phase AC power source is a 200V system. In the figure, during the period T1, the U-phase potential is the highest and the V-phase potential is the lowest. During this period, current flows from the first input terminal (U-phase) to the second input terminal (V-phase). At this time, when the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching element TR5 are turned on, the first diode D1, the third boost capacitor C3, and the fourth charging are performed. A current flows through the path of the diode D10 for charging and the third charging switching element TR3 to charge the third boost capacitor C3.

  In addition, when the second charging switching element TR2, the fourth charging switching element TR4, and the sixth charging switching element TR6 are turned on during the period T1 shown in FIG. 5, the first charging diode D7, A current flows through the path of the second charging switching element TR2, the second boost capacitor C2, and the fourth diode D4 to charge the second boost capacitor C2.

  In the period T2 shown in FIG. 5, the U-phase potential is the highest and the W-phase potential is the lowest. In this period, the current flows from the first input terminal (U-phase) to the third input terminal (W-phase). . At this time, when the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching element TR5 are turned on, the first diode D1, the fifth boost capacitor C5, and the sixth charging A current flows through the path of the diode for diode D12 and the fifth charging switching element TR5 to charge the fifth boost capacitor C5.

  In addition, when the second charging switching element TR2, the fourth charging switching element TR4, and the sixth charging switching element TR6 are turned on in the period T2 shown in FIG. 5, the first charging diode D7, A current flows through the path of the second charging switching element TR2, the second boost capacitor C2, and the sixth diode D6 to charge the second boost capacitor C2.

  In the period T3 shown in FIG. 5, the V-phase potential is the highest and the W-phase potential is the lowest. In this period, the current flows from the first input terminal (V-phase) to the third input terminal (W-phase). . At this time, when the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching element TR5 conduct, the third diode D3, the fifth boost capacitor C5, and the sixth charging A current flows through the path of the diode for diode D12 and the fifth charging switching element TR5 to charge the fifth boost capacitor C5.

  In addition, when the second charging switching element TR2, the fourth charging switching element TR4, and the sixth charging switching element TR6 are turned on in the period T3 shown in FIG. 5, the third charging diode D9, Current flows through the path of the fourth charging switching element TR4, the fourth boost capacitor C4, and the sixth diode D6 to charge the fourth boost capacitor C4.

  In the T4 period shown in FIG. 5, the V-phase potential is the highest and the U-phase potential is the lowest. In this period, the current flows from the second input terminal (V-phase) to the first input terminal (U-phase). At this time, when the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching element TR5 are turned on, the third diode D3, the first boost capacitor C1, and the second charging are performed. A current flows through the path of the diode for diode D8 and the first charging switching element TR1 to charge the first boost capacitor C1.

  Further, when the second charging switching element TR2, the fourth charging switching element TR4, and the sixth charging switching element TR6 are turned on in the period T4 shown in FIG. 5, the third charging diode D9, Current flows through the charging switching element TR4, the fourth boost capacitor C4, and the second diode D2 to charge the fourth boost capacitor C4.

  In the T5 period shown in FIG. 5, the W-phase potential is the highest and the U-phase potential is the lowest. In this period, current flows from the third input terminal (W-phase) to the first input terminal (U-phase). At this time, when the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching element TR5 are turned on, the fifth diode D5, the first boost capacitor C1, and the second charging A current flows through the path of the diode for diode D8 and the first charging switching element TR1 to charge the first boost capacitor C1.

  Further, when the second charging switching element TR2, the fourth charging switching element TR4, and the sixth charging switching element TR6 are turned on during the period T5 shown in FIG. 5, the fifth charging diode D11, Current flows through the charging switching element TR6, the sixth boosting capacitor C6, and the second diode D2 to charge the sixth boosting capacitor C6.

  In the period T6 shown in FIG. 5, the potential of the W phase is the highest and the potential of the V phase is the lowest. In this period, the current flows from the third input terminal (W phase) to the second input terminal (V phase). At this time, when the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching element TR5 are turned on, the fifth diode D5, the third boost capacitor C3, and the fourth charging are performed. A current flows through the path of the diode D10 for charging and the third charging switching element TR3 to charge the third boost capacitor C3.

  Further, when the second charging switching element TR2, the fourth charging switching element TR4, and the sixth charging switching element TR6 are turned on in the period T6 shown in FIG. 5, the fifth charging diode D11, Current flows through the path of the charging switching element TR6, the sixth boosting capacitor C6, and the fourth diode D4 to charge the sixth boosting capacitor C6.

  From the above, the first boost capacitor C1 to the sixth boost capacitor C6 are charged, and the boosted voltage (for example, 200V → 400V) is input as the input voltage of the inverter circuit INV. At this time, the first charging switching element, the third charging switching element, the fifth charging switching element, the second charging switching element, the fourth charging switching element, and the sixth charging switching element. Are alternately conducted at a predetermined high frequency (for example, several kHz to several tens of kHz), and the boosted direct current is used to charge the first boost capacitor C1 to the sixth boost capacitor C6 at a high frequency and boost them to a predetermined voltage. The voltage ripple value decreases with higher frequency. The switching frequency of the charging switching element is set to several kHz to several tens of kHz, but about 20 kHz is desirable in consideration of the audible region and the loss of the charging switching element. Further, the sum of the capacitance of the smoothing capacitor C7 and the respective capacities of the first boost capacitor C1 to the sixth boost capacitor C6 is made the same, the smoothing capacitor C7 is deleted, and the first boost capacitor C1 to the sixth boost capacitor C6. May be used instead of the smoothing capacitor C7.

“Embodiment 2”
FIG. 3 is a waveform diagram for explaining the operation of the second embodiment of the present invention. The waveform in FIG. 3A shows the input voltage detection signal Iv, the waveform in FIG. 3B shows the first comparison signal Cp1 shown in FIG. 2, and the waveform in FIG. 3C shows the AND signal shown in FIG. The signal Ad2 is shown, the waveform of FIG. 3D shows the first charge control signal Tc1, and the waveform of FIG. 3E shows the second charge control signal Tc2.

Next, the operation when the three-phase AC power supply is a 200V system will be described.
When a magnet switch or the like (not shown) is turned on, the three-phase AC power supply is rectified and converted into a pulsating DC voltage when it is input to the three-phase full-wave rectifier circuit. The input voltage detection circuit IV detects a pulsating DC voltage and outputs it as an input voltage detection signal Iv shown in FIG.

  At time t = t1 shown in FIG. 3, the first comparison circuit CP1 shown in FIG. 2 compares the input reference value Vr1 set by the input reference setting circuit VR1 with the input voltage detection signal Iv, and the input voltage detection signal Iv. Becomes larger than the input reference value Vr1, the first comparison signal Cp1 shown in FIG. 3B is set to the high level. The time limit circuit TI starts a time limit when the first comparison signal Cp1 becomes High level, and the first AND circuit AD1 performs an AND logic of the first comparison signal Cp1 and the time limit signal Ti, and time t = t2 At this time, the first AND signal Ad1 is set to High level and output.

  The second comparison circuit CP2 shown in FIG. 2 compares the reference voltage value Vr2 set by the reference voltage setting circuit VR2 with the input voltage detection signal Iv, and when the input voltage detection signal Iv is smaller than the reference voltage value Vr2, The second comparison signal Cp2 becomes low level, and is set to high level by the inverting circuit IN and is input to the second AND circuit AND2.

  At time t = t2, the second AND circuit has the first AND signal Ad1, which is an input signal, at the High level, and the inverted signal In is also at the High level, so the second AND signal Ad2 is at the High level. When the second AND signal Ad2 becomes High level, the switching element drive circuit SD determines that the three-phase AC power supply is a 200V system and repeats the first and second signals as shown in FIGS. 1 charge control signal Tc1 and 2nd charge control signal Tc2 are output. At this time, the output frequencies of the first charge control signal Tc1 and the second charge control signal Tc2 are set to a high frequency of 20 kHz that is six times (for example, 360 Hz) or more of the three-phase AC power supply frequency.

  At time t = t2, when the first charging control signal Tc1 shown in FIG. 3 (D) becomes a high level, the first charging switching element TR1, the third charging switching element TR3, and the fifth charging switching. Element TR5 conducts and shuts off at time t = t3.

  At time t = t4, when the second charge control signal Tc2 shown in FIG. 3 (E) becomes a high level, the second charge switching element TR2, the fourth charge switching element TR4, and the sixth charge switching. Element TR6 conducts and shuts off at time t = t5.

Next, the operation when the three-phase AC power source is a 400V system will be described.
The second comparison circuit CP2 shown in FIG. 2 compares the reference voltage value Vr2 set by the reference voltage setting circuit VR2 with the input voltage detection signal Iv, and when the input voltage detection signal Iv is larger than the reference voltage value Vr2, The comparison signal Cp2 of No. 2 becomes High level, is set to Low level by the inverting circuit IN, and is input to the second AND circuit AND2.

  At time t = t2 shown in FIG. 3, the second AND circuit AND2 performs AND logic between the High level of the first AND signal Ad1 and the Low level of the inverted signal In, and sets the second AND signal Ad2 to the Low level. To. When the second AND signal Ad2 becomes low level, the switching element drive circuit SD determines that the three-phase AC power supply is 400V system and outputs the first charge control signal Tc1 and the second charge control signal Tc2. Stop.

  The charging control circuit CR stops the output of the first charging control signal Tc1 and the second charging control signal Tc2, and shuts off the first charging switching element TR1 to the sixth charging switching element TR6. At this time, the three-phase full-wave rectifier circuit three-phase full-wave rectifies the 400-V three-phase AC power source to generate a pulsating DC voltage, which is smoothed by the smoothing capacitor C7 and output to the inverter circuit INV. With the above-described charging control circuit CR, it is possible to accurately determine whether the three-phase AC power source is the 200V system or the 400V system.

It is an electrical connection figure of the power supply device for arc processing of this invention. FIG. 2 is a detailed diagram of a charge control circuit CR shown in FIG. It is a wave form diagram explaining the operation | movement of Embodiment 2 of this invention. It is an electrical connection figure of the power supply apparatus for arc processing of a prior art. It is an input waveform figure of a three-phase alternating current power supply.

Explanation of symbols

AD1 first AND circuit AD2 first AND circuit C1 first boost capacitor C2 second boost capacitor C3 third boost capacitor C4 fourth boost capacitor C5 fifth boost capacitor C6 sixth boost capacitor C7 smoothing Capacitor C8 Capacitor C9 Capacitor C10 Capacitor C11 Smoothing Capacitor C12 Smoothing Capacitor CR Charging Control Circuit CP1 First Comparison Circuit CP2 Second Comparison Circuit D1 First Diode D2 Second Diode D3 Third Diode D4 Fourth Diode D5 5th diode D6 6th diode D7 1st charging diode D8 2nd charging diode D9 3rd charging diode D10 4th charging diode D11 5th charging diode D12 6th charging Diode D13 diode D14 diode D15 diode D16 diode D17 diode D18 diode D19 diode D20 diode D21 diode DCL DC reactor DR1 secondary rectifier circuit ER comparison operation circuit Er comparison operation signal ID output current detection circuit Id output current detection signal IN inversion circuit In inversion signal IR output current setting circuit Ir output current setting signal IV input voltage detection circuit Iv input voltage detection signal INV inverter circuit INT main transformer M workpiece SC output control circuit SD switching element drive circuit Sc1 first output control signal Sc2 second Output control signal SW1 voltage changeover switch SW2 voltage changeover switch SW3 voltage changeover switch TH torch TI time limit circuit Tc1 first charge control signal Tc2 second charge Control signal TR1 1st switching element for charging TR2 2nd switching element for charging TR3 3rd switching element for charging TR4 4th switching element for charging TR5 5th switching element for charging TR6 6th switching element for charging VR1 input reference setting circuit Vr1 input reference setting signal (input reference value)
VR2 reference voltage setting circuit Vr2 reference voltage setting signal (reference voltage value)

Claims (2)

  A three-phase full-wave rectifier circuit comprising a three-phase bridge diode that outputs a pulsating DC voltage by rectifying a three-phase AC power input from the first input terminal to the third input terminal, and the three-phase full-wave rectifier circuit A smoothing capacitor that is provided in parallel to smooth the pulsating DC voltage, an inverter circuit that converts the DC voltage into a high-frequency AC voltage, an output control circuit that controls the output of the inverter circuit, and a high frequency suitable for arc machining In an arc machining power supply apparatus, comprising a main transformer for converting to an AC voltage, and a secondary rectifier circuit for rectifying the output of the main transformer and outputting a DC voltage, the first boost capacitor to the sixth The boost capacitor has the same capacity, and is provided between the three-phase full-wave rectifier circuit and the smoothing capacitor in series with the first boost capacitor and the second boost capacitor. A first series circuit, a second series circuit provided between the three-phase full-wave rectifier circuit and the smoothing capacitor with the third boost capacitor and the fourth boost capacitor in series, A third series circuit provided between the three-phase full-wave rectifier circuit and the smoothing capacitor with the five boost capacitors and the sixth boost capacitor connected in series; the first input terminal; A first charging switching element and a second charging switching element which are provided between the first and second series circuits and supply a charging current caused by a predetermined potential difference of each phase to the first series circuit; and A first charging diode provided in parallel in the opposite direction to the first charging switching element; a second charging diode provided in parallel in the opposite direction to the second charging switching element; and the second input. A third charging switching element and a fourth charging which are provided between a child and a middle point of the second series circuit and which supply a charging current generated by a predetermined potential difference of each phase to the second series circuit A third charging diode provided in parallel in the reverse direction to the switching element for charging and the fourth charging switching element, and a fourth charging diode provided in parallel in the reverse direction to the fourth charging switching element; A fifth switching element for charging, which is provided between the third input terminal and the middle point of the third series circuit and supplies a charging current generated by a predetermined potential difference of each phase to the third series circuit. And a sixth charging switching element, a fifth charging diode provided in parallel in the reverse direction to the fifth charging switching element, and a sixth charging switching element provided in parallel in the reverse direction. When the DC voltage of the sixth charging diode and the three-phase full-wave rectifier circuit is equal to or lower than a predetermined reference voltage value, the first charging control signal and the second charging signal of the same time with the maximum conduction ratio shifted from each other by a half cycle The charging control signal is repeatedly output, and the first charging switching element, the third charging switching element, and the fifth charging switching element are turned on according to the first charging control signal, and the second charging is performed. The second charging switching element, the fourth charging switching element, and the sixth charging switching element are conducted in response to a control signal, and the first charging is performed when the DC voltage is equal to or higher than the reference voltage value. A charge control circuit that stops output of the control signal and the second charge control signal and shuts off the first to sixth charge switching elements; Over click machining power supply apparatus. 2. The arc machining power supply device according to claim 1, wherein the charge control circuit compares the DC voltage with the reference voltage after a predetermined time from when the three-phase AC power is turned on. .

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