JP5033596B2 - Power supply device and power supply device for arc machining - Google Patents

Description

  The present invention relates to a power supply device having an inverter circuit for converting an input AC power source such as a commercial power source into a DC voltage and converting the DC voltage into a predetermined AC voltage, and an arc machining power source device using the power source device It is.

As shown in Patent Document 1 and Patent Document 2, for example, Patent Literature 1 and Patent Literature 2 describe a power supply device that uses a commercial power supply (three-phase AC power supply) that is rectified by a rectifier circuit and smoothed by a smoothing capacitor. A DC conversion circuit for conversion and an inverter circuit for AC conversion configured by a bridge circuit of a plurality of switching elements (first to fourth switching elements) are provided. In the inverter circuit, a predetermined combination of switching elements are synchronously turned on / off (PWM control) to convert a DC voltage from the DC conversion circuit 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.
JP 2005-230859 A JP-A-10-191656

  Incidentally, in order to adjust the arc machining output in the above-described arc machining power supply device, the duty of the control pulse supplied to each switching element of the inverter circuit is changed. That is, the on-pulse width of the control pulse is set wide to make the arc machining output medium / high, but the on-pulse width of the control pulse is set narrow to make the arc machining output low. For this reason, when the output is set to a lower output even during the low output setting, the on-pulse width of the control pulse becomes extremely narrow, and in this case, there is a case that the control pulse disappears for some reason. Then, the arc machining output becomes unstable, for example, the ripple of the output current becomes large, or the magnetic field is generated in the transformer at the subsequent stage of the inverter circuit, causing various problems to the arc machine.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a power supply device and an arc machining power supply device capable of stabilizing the output at the time of low output.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a bridge using a DC conversion circuit that converts an input AC power source into a DC voltage by a rectifier circuit and a smoothing circuit, and first to fourth switching elements. An inverter circuit configured by a circuit, wherein the first to fourth switching elements are driven on and off for each predetermined set to convert a DC voltage from the DC conversion circuit into a high-frequency AC voltage, and the first to first switching elements A control circuit that outputs a switching control signal for switching control of the four switching elements to each of the switching elements and adjusts a high-frequency AC voltage output from the inverter circuit by changing an on-pulse width of the switching control signal. The control circuit includes a power supply device, wherein the switching element sufficiently turns on an ON pulse width of the switching control signal. When a low output corresponding to the required width is requested by changing the output to a predetermined width or greater, the on-pulse width of the switching control signal is maintained at the predetermined width or the predetermined width or more. The gist of the invention is to cause a phase difference between the switching control signals output to a pair of the switching elements, and adjust the time during which the switching elements of the pair are simultaneously turned on according to the required output.

  In the present invention, when a request for low output is made, the control circuit outputs the switching control signal to the same set of switching elements while maintaining the on-pulse width of the switching control signal at a predetermined width that allows the switching elements to be sufficiently turned on or a predetermined width or more. A phase difference is generated between the switching control signals to be adjusted, and the time during which the switching elements of the same group are simultaneously turned on is adjusted according to the required output. As a result, even if a request for low output is made, the switching element is reliably turned on with a predetermined width that can be sufficiently turned on, so that the output from the inverter circuit is stabilized.

  According to a second aspect of the present invention, in the power supply device according to the first aspect, when the low output is required, the control circuit responds to one of the switching control signals output to the switching element of the same set. The gist of this is to delay the other and cause a phase difference.

  In the present invention, when a request for low output is made, the control circuit delays the other of the switching control signals output to the same pair of switching elements to cause a phase difference. That is, since only the other phase of the switching control signal needs to be changed, there are few means for delaying the phase, which can contribute to simplification of the configuration of the control circuit.

  According to a third aspect of the present invention, in the power supply device according to the first or second aspect, the control circuit outputs the switching to the switching element of the same set when the required output is higher than the low output. The gist is to match the phases of the control signals and simultaneously turn on and off the switching elements of the same set.

  In the present invention, when the required output is higher than the low output, the control circuit matches the phases of the switching control signals output to the same set of switching elements, and simultaneously turns on and off the same set of switching elements. As a result, the on-pulse width of the switching control signal can be adjusted more widely, and the demand for higher output can be met.

  Invention of Claim 4 produces | generates the voltage for arc processing which performs the arc process of a workpiece from the high frequency alternating voltage output from the inverter circuit of the power supply device of any one of Claims 1-3 It is the power supply device for arc processing comprised so that.

  In the present invention, since the power supply device according to any one of claims 1 to 3 is used, the power supply device for arc machining that can obtain the effects of the above-mentioned claims can be provided.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device and arc processing power supply device which can aim at the output stabilization at the time of a low output can be provided.

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. An arc machining power supply device 11 used for such an arc machine 10 includes a DC conversion circuit 12 that converts a commercial power supply (three-phase AC voltage) of, for example, 200 V or 400 V into a DC voltage, and a predetermined DC voltage. And an inverter circuit 13 for converting the high-frequency AC voltage to a high-frequency AC voltage.

  The DC conversion circuit 12 is configured by a bridge circuit using a diode and primary-side rectifier circuit DR1 for full-wave rectification of a three-phase input AC power supply, and first and second power supply lines L1 on the output side of the rectifier circuit DR1. , L2 connected in series and a smoothing capacitor C1 for smoothing the output voltage of the rectifier circuit DR1. The DC conversion circuit 12 generates a DC voltage from the input AC power supply by the rectifier circuit DR1 and the smoothing capacitor C1, and the DC voltage is supplied to the inverter circuit 13 at the subsequent stage.

  The inverter circuit 13 is connected to the power supply lines L1 and L2, and is configured by a bridge circuit using first to fourth switching elements TR1 to TR4 made of four IGBTs. The diodes D1 to D4 are reversely connected to the first to fourth switching elements TR1 to TR4, respectively. The first to fourth switching elements TR1 to TR4 are based on the PWM control of the control circuit 14, and the combination of the first and fourth switching elements TR1 and TR4 and the combination of the second and third switching elements TR2 and TR3. Are alternately turned on and off. As a result, the DC voltage generated by the DC conversion circuit 12 is converted into a predetermined high-frequency AC voltage and supplied to the primary coil of the transformer INT as an inverter output voltage.

  The inverter output voltage (high-frequency AC voltage) generated by the inverter circuit 13 is supplied to the primary coil of the transformer INT, and the secondary rectifier circuit DR2 and the DC reactor DCL are provided on the secondary side of the transformer INT. It is done. The secondary 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 this machining DC 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 outputs a comparison operation signal Er obtained by comparing the output current detection signal Id and the output current setting signal Ir, that is, a difference between the output current value and the set value, to the control circuit 14 as a comparison operation signal Er. The comparison calculation signal Er is used for feedback control in the control circuit 14.

  The control circuit 14 determines whether the setting of the arc machining output by the output current setting device IR is, for example, a medium / high output in which the duty setting range of the PWM control is within a range of 5% to 45% with respect to 0% to a maximum of 45%. The PWM control signals S1 to S4 for controlling the respective switching elements TR1 to TR4 are generated according to whether the duty is a low output of 5% or less (the numerical value is not limited to these). The driver circuit 15 outputs drive control signals Vg1 to Vg4 based on the PWM control signals S1 to S4 to the gates of the switching elements TR1 to TR4, respectively.

  Here, regarding the generation of the PWM control signals S1 to S4, the control circuit 14 obtains the inverter output from the triangular wave voltage and the pulse width setting voltage as shown in FIG. 4, and the pulse width for the triangular wave voltage according to the output setting value. By raising or lowering the set voltage, the on-pulse width of the inverter output is changed. If the output setting value is set to medium to high, the pulse width setting voltage is lowered to widen the inverter output on-pulse width, and if the output setting value is set to low, the pulse width setting voltage is raised to increase the inverter output on-pulse width. Is narrowed.

  In the case of the configuration in which the switching elements TR1 to TR4 are simultaneously turned on / off by the PWM control signals S1 to S4 having the same on-pulse width as that of the inverter output, when the on-pulse width becomes extremely narrow, for example, driving is performed through the driver circuit 15. If the control signals Vg1 to Vg4 do not rise sufficiently, a so-called tooth loss occurs in which the control pulse disappears. Then, the switching elements TR1 to TR4 are not normally turned on, and various problems such as output instability and bias are generated. For this reason, the control circuit 14 of the present embodiment is configured to provide an inverter output corresponding to the output set value while ensuring at least the on-pulse width that allows the switching elements TR1 to TR4 to be normally turned on.

  That is, the control circuit 14 takes the OR of the inverter output obtained from the triangular wave voltage and the pulse width setting voltage and the width guarantee pulse with the minimum pulse width T0, and the on-pulse width of the inverter output is wider than that of the width guarantee pulse. When the medium / high output is set, PWM control signals S1 to S4 having the same on-pulse width as the obtained inverter output and the same set of phases are generated. As a result, as shown in FIG. 2, drive control signals Vg1 to Vg4 are generated based on the PWM control signals S1 to S4 having the same on-pulse width as the obtained inverter output, and the same based on the drive control signals Vg1 to Vg4. The pair of switching elements TR1 to TR4 are simultaneously turned on and off to generate an inverter output voltage composed of a high-frequency AC voltage.

  Further, in the low output setting where the on-pulse width of the inverter output is narrower than that of the width guarantee pulse, the on-pulse width of the PWM control signals S1 to S4 is set to be the same as the width guarantee pulse as shown in FIG. The phase of the PWM control signal S4 is delayed with respect to the PWM control signal S1, and the phase of the PWM control signal S3 is delayed with respect to the PWM control signal S2 by the narrowing (time T1). At this time, the phase is delayed from the ON pulse of the next PWM control signals S1 to S4 in which the ON pulse width of the inverter output is narrower than that of the width guarantee pulse. That is, the output voltage corresponding to the obtained inverter output is generated by adjusting the time during which the switching elements TR1 to TR4 of the same group are shifted on and off at the same time in this way. As a result, as shown in FIG. 3, even a narrow inverter output voltage can be reliably output, and the arc machining output is stabilized.

Next, characteristic effects of the present embodiment will be described.
(1) The control circuit 14 of the present embodiment maintains the on-pulse width of the PWM control signals S1 to S4 at the minimum pulse width T0 that can be sufficiently turned on by the switching elements TR1 to TR4 when a request for low output is made. A phase difference is generated between the PWM control signals S1 to S4 output to the same group of switching elements TR1 to TR4, and the time during which the same group of switching elements TR1 to TR4 are simultaneously turned on is adjusted according to the required output. did. Thereby, even if a low output is requested, the switching elements TR1 to TR4 are reliably turned on with a predetermined width that can be sufficiently turned on, so that the output from the inverter circuit 13 and thus the output of the arc machining power supply device 11 can be further increased. It becomes stable.

  (2) When a request for low output is made, the control circuit 14 of the present embodiment delays the other of the PWM control signals S1 to S4 output to the switching elements TR1 to TR4 of the same group, thereby causing a phase difference. It was made to produce. Specifically, the control signal S4 is delayed with respect to the PWM control signal S1, and the control signal S3 is delayed with respect to the PWM control signal S2. That is, since only the phase of the PWM control signals S3 and S4 needs to be changed, there are few means for delaying the phase, which can contribute to simplification of the configuration of the control circuit 14.

  (3) The control circuit 14 of the present embodiment makes the phases of the PWM control signals S1 to S4 output to the same set of switching elements TR1 to TR4 coincide with each other when the required output is on the high output side. -TR4 was turned on and off at the same time. As a result, the on-pulse width of the PWM control signals S1 to S4 can be adjusted more widely, and a request for higher output can be met.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the lower limit of the on-pulse width of the switching elements TR1 to TR4 is the minimum pulse width T0 that can be turned on, but it may be a predetermined width larger than the minimum pulse width T0.

  In the above embodiment, the phase difference is generated by delaying the other of the PWM control signals S1 to S4 output to the switching elements TR1 to TR4 of the same group, but the phases of the two are shifted to each other. A phase difference may be generated.

  In the above embodiment, the phase control of the PWM control signals S1 to S4 output to the same set of switching elements TR1 to TR4 is performed only at the time of low output, but the phase control is also performed at the time of medium and high output. Also good.

-In above-mentioned embodiment, although IGBT was used for each switching element TR1-TR4, you may comprise using switching elements other than IGBT.
In the above-described embodiment, the present invention is applied to a device that performs PWM control, but may be applied to a device that performs other switching control such as PFM control.

  In the above embodiment, the arc machining power supply device 11 is used. However, the power supply device is used for a purpose other than the arc machining, for example, an AC-AC conversion power supply device having a DC conversion circuit 12 and an inverter circuit 13. Also good. Moreover, you may implement in the DC-AC conversion power supply device which has the inverter circuit 13. FIG.

Next, a technical idea that can be grasped from the above embodiment and another example will be added below.
(B) Consists of a bridge circuit using the first to fourth switching elements, and the first to fourth switching elements are turned on and off for each predetermined set to convert the input DC voltage to a high-frequency AC voltage and output it. An inverter circuit to
A switching control signal for switching control of the first to fourth switching elements is output to each switching element, and an on-pulse width of the switching control signal is changed to adjust a high-frequency AC voltage output from the inverter circuit A power supply device comprising a control circuit for
The control circuit changes the on pulse width of the switching control signal to a predetermined width or more that allows the switching element to be sufficiently turned on to correspond to the requested output, and when a low output corresponding to the predetermined width or less is requested, While maintaining the on-pulse width of the switching control signal to be a predetermined width or a predetermined width or more, a phase difference is generated between the switching control signals output to the switching elements of the same group, and the switching elements of the same group are simultaneously turned on. A power supply device that adjusts time according to the required output.

  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 apparatus for arc processing in this embodiment. It is a wave form diagram at the time of medium / high output setting of a power supply device. It is a wave form diagram at the time of the low output setting of a power supply device. It is a wave form chart for explaining generation of a PWM control signal.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Power supply device, 12 ... DC converter circuit, 13 ... Inverter circuit, 14 ... Control circuit, C1 ... Smoothing capacitor (smoothing circuit), DR1 ... Primary side rectifier circuit (rectifier circuit), M ... Work object, S1-S4 ... PWM control signal (switching control signal), TR1 to TR4 ... first to fourth switching elements, T0 ... minimum pulse width (predetermined width).

Claims (4)

A DC conversion circuit that converts an input AC power source into a DC voltage by a rectifier circuit and a smoothing circuit;
It is composed of a bridge circuit using first to fourth switching elements, and the first to fourth switching elements are driven on and off for each predetermined set to convert the DC voltage from the DC conversion circuit into a high-frequency AC voltage. Output inverter circuit,
A switching control signal for switching control of the first to fourth switching elements is output to each switching element, and an on-pulse width of the switching control signal is changed to adjust a high-frequency AC voltage output from the inverter circuit A power supply device comprising a control circuit for
The control circuit changes the on pulse width of the switching control signal to a predetermined width or more that allows the switching element to be sufficiently turned on to correspond to the requested output, and when a low output corresponding to the predetermined width or less is requested, While maintaining the on-pulse width of the switching control signal to be a predetermined width or a predetermined width or more, a phase difference is generated between the switching control signals output to the switching elements of the same group, and the switching elements of the same group are simultaneously turned on. A power supply device that adjusts time according to the required output. The power supply device according to claim 1,
The power supply device according to claim 1, wherein when the low output is required, the control circuit delays the other of the switching control signals output to the switching elements of the same group to generate a phase difference. The power supply device according to claim 1 or 2,
When the required output is higher than the low output, the control circuit matches the phases of the switching control signals output to the switching elements of the same set, and simultaneously turns on and off the switching elements of the same set. Power supply.   It is comprised so that the voltage for arc processing which performs the arc process of a workpiece may be produced | generated from the high frequency alternating voltage output from the inverter circuit of the power supply device of any one of Claims 1-3. A power supply device for arc machining.

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