JP2014018831A - Power supply device for welding, and method for controlling the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply device for welding, capable of improving stability of output control after an instantaneous event.SOLUTION: When a duration change occurs, a determination is made whether it is an arc duration or a short circuit duration, and also the determination is made whether it is a duration generated in an instantaneous event (instantaneous arc, or an instantaneous short circuit) according to a relationship with a precedent duration change. Also, a control target value (data Dt1-Dt6) is backed up to backup data Dta, Dtb every duration change, and at least the control target value immediately before the instantaneous event is retained until the determination that the instantaneous event occurs. Then, when it is determined that the instantaneous event occurs, the control target value immediately before the instantaneous event that is backed up is used by subsequent output control.

Description

  The present invention relates to a welding power source apparatus used in a consumable electrode type arc welding machine in which an arc period and a short-circuit period occur alternately, and a control method therefor.

  Conventionally, a consumable electrode type arc welder performs welding while feeding a wire electrode in accordance with arc consumption. At that time, an arc period in which an arc is generated from the electrode tip and a short-circuit period in which the electrode tip is in contact with the object to be welded are alternately repeated, and the control circuit of the welding power supply device takes the electrode material and feed rate into consideration. Output control (arc length control) is performed so that the output value of the power supply device during each period is an appropriate value.

  By the way, a short time instantaneous arc (instantaneous arc) may occur during a normal short circuit period, or a short time instantaneous short circuit (instant short circuit) may occur during a normal arc period. When the output control is performed again at the start of the normal period when such an instantaneous event returns to the normal period, the output value immediately after the instantaneous event greatly deviates from the desired output value, the output control becomes unstable, and welding is performed. There is concern that it may affect quality.

  This is because the control target value fluctuates each time from the start of the period to the end of the period, especially at the start of the period, because it is immediately after switching from the previous period where the event change such as arc or short circuit is large. One of the factors is that the target value fluctuates greatly. Therefore, if the output control is restarted at the start of each normal period when returning from an instantaneous event, the rise of the output current is delayed and the output current cannot be recovered quickly, and the arc becomes unstable. It is.

  Therefore, the control target value is recognized by the control circuit of the power supply device, and the control target value is replaced with a predetermined fixed value so that the output control can be continued from a specific arc state or short-circuit state upon recovery from the instantaneous event. Is considered. Thereby, the stability improvement of the output control after the return from the instantaneous event can be expected.

  For example, the techniques disclosed in Patent Documents 1 and 2 are not output control after returning from an instantaneous event, but as a control mode using a fixed value set in advance as a control target value immediately after switching from a normal short-circuit period to an arc period. If this is applied to the output control immediately after the instantaneous event, stabilization of the output control immediately after the instantaneous event can be expected.

JP 2006-021227 A JP 2009-183988 A

  However, since the output value such as the output current value immediately before the instantaneous event fluctuates depending on the situation at that time, the output control can be performed quickly even in the above control mode in which a fixed value is used as the control target value when returning from the instantaneous event. In some cases, it may take time for output control to become stable, and there is still room for improvement.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a welding power supply device and a welding power supply control method capable of improving the stability of output control after an instantaneous event. It is to provide.

  In order to solve the above-mentioned problem, the invention described in claim 1 is a welding power source apparatus used for a consumable electrode type arc welding machine in which an arc period and a short-circuit period are alternately generated, and an output value at each period is obtained. A welding power source apparatus including a control unit that calculates a control target value for performing output control including the control target value and performs output control based on the control target value. A period determining means for determining whether it is an arc period or a short-circuit period, an instantaneous event determining means for determining whether a period has occurred due to an instantaneous event when a period change occurs, and a period change Backing up the control target value every time, and comprising backup processing means for holding at least the control target value immediately before the instantaneous event until the determination that the instantaneous event has occurred, for determining that the instantaneous event has occurred Base There are controls output based on the control target value of the instantaneous event immediately before that had been the backup.

  In this invention, when a period change occurs, it is determined whether it is an arc period or a short-circuit period, and whether it is a period caused by an instantaneous event (instantaneous arc, instantaneous short-circuit) is determined based on the relationship with the previous period change. The Further, the control target value is backed up every time the period changes, and at least the control target value immediately before the instantaneous event is held until it is determined that the instantaneous event has occurred. When it is determined that an instantaneous event has occurred, output control is performed based on the control target value immediately before the instantaneous event that was backed up. In other words, continuous output control is performed across the instantaneous event, and the control target value immediately after the instantaneous event is based on the control target value immediately before the instantaneous event and reflects the output status immediately before the instantaneous event. As a result, the original output value can be promptly recovered after any instantaneous event, which contributes to improving the stability of output control after the instantaneous event.

  According to a second aspect of the present invention, in the welding power source device according to the first aspect, the backup processing means backs up the control target values of the arc period and the short-circuit period, and the control means Based on the determination that the instantaneous event has occurred, output control is performed based on the control target value backed up in the same period as that immediately after the instantaneous event.

  In this invention, each control target value of the arc period and the short-circuit period is backed up, and when it is determined that an instantaneous event has occurred, based on the control target value that has been backed up in the same period as that immediately after the instantaneous event. Since output control is performed, there is no confusion between periods, and appropriate output control is always possible.

According to a third aspect of the present invention, in the welding power supply device according to the first or second aspect, the backup processing means backs up the control target value only at the time of the period change.
In the present invention, since the control target value only at the time of period change is backed up, the load related to the backup process can be reduced, and the number of control target value data backups can be reduced.

  According to a fourth aspect of the present invention, in the welding power supply device according to any one of the first to third aspects, the control means performs the backup based on the determination that the instantaneous event has occurred. The output control is performed using the control target value immediately before the instantaneous event as it is.

  In this invention, when it is determined that an instantaneous event has occurred, the control target value immediately before the instantaneous event that has been backed up is used as it is for output control. Thereby, when setting the control target value at the time of determining that an instantaneous event has occurred, no calculation is required, and an increase in calculation processing load can be prevented.

  According to a fifth aspect of the present invention, in the welding power supply device according to any one of the first to third aspects, the control means performs the backup based on the determination that the instantaneous event has occurred. The control target value immediately before the instantaneous event is corrected so as to cancel the influence of the instantaneous event, and the output control is performed using the corrected control target value.

  In this invention, when it is determined that an instantaneous event has occurred, the control target value immediately before the instantaneous event that has been backed up is corrected so as to cancel the influence of the instantaneous event, and the corrected control target value is output. Used for control. As a result, the output control immediately after the instantaneous event is performed in consideration of the influence of the instantaneous event, so that the stability of the output control immediately after the instantaneous event is further improved.

  The invention according to claim 6 is a control method of a welding power source device used in a consumable electrode type arc welding machine in which an arc period and a short-circuit period occur alternately, and performs output control including an output value at each period. A control method for a welding power supply apparatus that calculates a control target value for the output and performs output control based on the control target value, and determines whether an arc period or a short-circuit period when a period change occurs. When a change occurs, it is determined whether it is a period caused by an instantaneous event based on the relationship with the previous period change, the control target value is backed up every time the period changes, and it is determined that the instantaneous event has occurred Until at least the control target value immediately before the instantaneous event is held, and based on the determination that the instantaneous event has occurred, output control is performed based on the control target value immediately before the instantaneous event that has been backed up .

  In the present invention, the same effect as that of claim 1 can be obtained.

  ADVANTAGE OF THE INVENTION According to this invention, the control method of the power supply device for welding which can aim at the stability improvement of the output control after an instantaneous event, and the power supply device for welding can be provided.

The electric block diagram of the arc welding machine (power supply device for welding) in one Embodiment. Explanatory drawing for demonstrating the control action of the form.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
As shown in FIG. 1, the consumable electrode type arc welding machine 10 supplies the output power generated by the welding power supply device 11 to the wire electrode WE supported by the torch TH to generate an arc at the tip thereof. The welding object (base material) M is welded. In the consumable electrode type arc welding machine 10, since the wire electrode WE is consumed by the arc, a feeding device WF that feeds the wire electrode WE according to the consumption is used.

The welding power supply device 11 includes a DC conversion circuit 12, an inverter circuit 13, an auxiliary switching circuit 14, a transformer INT, and an output conversion circuit 15.
The DC conversion circuit 12 includes a rectifier circuit DR1 composed of a diode bridge and a smoothing capacitor C1, and converts three-phase AC input power supplied from a commercial power source into DC power. The DC conversion circuit 12 outputs the converted DC power to the inverter circuit 13 through a pair of power supply lines L1 and L2.

  The inverter circuit 13 is configured by a bridge circuit that uses four switching elements TR1 to TR4 such as IGBTs, the switching elements TR1 and TR2 are disposed on the power supply line L1, and the switching elements TR3 and TR4 are disposed on the power supply line L2. ing. Reflux diodes D1 to D4 are connected to the switching elements TR1 to TR4, respectively. A control pulse signal is input from the control circuit 21 to the gates of the switching elements TR1 to TR4, and the switching elements TR1 and TR4 and the switching elements TR2 and TR3 are alternately turned on and off in pairs. Each of the switching elements TR1 to TR4 converts the input DC power into high-frequency AC power based on the on / off drive, and supplies the converted high-frequency AC power to the primary coil of the transformer INT.

  Between the inverter circuit 13 and the DC conversion circuit 12, an auxiliary switching circuit 14 having a switching element TR5 such as an IGBT and an auxiliary capacitor C2 is provided. The switching element TR5 is connected to the free-wheeling diode D5 and is disposed on the power supply line L2 at the subsequent stage of the DC conversion circuit 12. An auxiliary capacitor C2 is connected between the power supply lines L1 and L2 connected to the inverter circuit 13 at the subsequent stage of the switching element TR5. A control pulse signal is input from the control circuit 21 to the gate of the switching element TR5, and the switching element TR5 is driven on and off in conjunction with the switching elements TR1 to TR4 of the inverter circuit 13.

  The transformer INT adjusts the voltage of the high-frequency AC power generated by the inverter circuit 13 and outputs the high-frequency AC power adjusted to a predetermined voltage from the secondary coil to the output conversion circuit 15.

  The output conversion circuit 15 includes a rectifier circuit DR2, a DC reactor DCL, and a smoothing capacitor C3. The rectifier circuit DR2 includes two diodes whose anodes are connected to both ends of the secondary coil of the transformer INT, and the cathode of each diode is connected to the DC reactor DCL. The direct current reactor DCL is disposed on the output line L3, and the output line L4 is connected to the intermediate point of the secondary coil of the transformer INT. The smoothing capacitor C3 is connected between the output lines L3 and L4. The output conversion circuit 15 converts the high-frequency AC power output from the transformer INT into DC output power suitable for arc welding by the rectifier circuit DR2, the DC reactor DCL, and the smoothing capacitor C3.

  The output terminal a of the power supply device 11 to which the output line L3 is connected is connected to the wire electrode WE of the torch TH via a cable, and the output terminal b of the power supply device 11 to which the output line L4 is connected is connected via a cable. It is connected to the welding object M. The arc welding of the welding object M is performed by generating an arc at the tip of the electrode WE by supplying the output power generated by the power supply device 11 to the wire electrode WE.

  The control circuit 21 provided in the power supply device 11 receives an input of a start signal from the start switch TS and enters a start state in which a control operation including switching control of the inverter circuit 13 and the auxiliary switching circuit 14 is possible. The control circuit 21 performs soft switching control for reducing switching loss by interlocking the auxiliary switching circuit 14 with the inverter circuit 13 together with switching control of the inverter circuit 13. This soft switching control is performed by turning off the switching element TR5 of the auxiliary switching circuit 14 prior to turning off the switching elements TR1 to TR4 of the inverter circuit 13, and turning off the switching elements TR1 to TR4 after discharging of the auxiliary capacitor C2. This is control for reducing switching loss in the switching elements TR1 to TR5.

  The control circuit 21 calculates the control target value from time to time. The control circuit 21 receives the output voltage setting value from the output voltage setting circuit VR and the output voltage detection value from the output voltage detection circuit VD. These input values, the material of the electrode WE, and the supply of the electrode WE Control target values related to output control (arc length control) such as output current target value, output voltage target value, and the like are calculated using various parameters including speed. The control circuit 21 sets a control pulse signal that is suitable output power for the inverter circuit 13 and the auxiliary switching circuit 14 from the control target value calculated at each time, and performs output control to achieve a desired output value. ing.

The control circuit 21 includes a period determination unit 22, an instantaneous event determination unit 23, a backup processing unit 24, and a memory 25.
The period determination unit 22 determines whether it is an arc period or a short circuit period. In the consumable electrode type arc welding machine 10, welding is performed while feeding the wire electrode WE from the feeding device WF as the wire electrode WE is consumed by the arc during welding, so that an arc is generated from the tip of the wire electrode WE. The period and the short-circuit period in which the tip of the wire electrode WE contacts the welding object M are alternately repeated. At this time, since the output voltage is high in the arc period and the output voltage is low in the short circuit period, the period determination unit 22 determines whether the arc period or the short circuit period is based on a comparison between the output voltage (output voltage detection value) and a threshold value. I do.

  The instantaneous event determination unit 23 determines whether an instantaneous short circuit has occurred during the arc period or whether an instantaneous arc has occurred during the short circuit period. That is, the instantaneous event determination unit 23 measures time from the time when the period determination unit 22 determines the change in the period between the arc and the short circuit (when the threshold is crossed), and whether the next period change has occurred within a predetermined time. Determine. If the next period change does not occur within the predetermined time, the instantaneous event determination unit 23 determines that an instantaneous event (instantaneous arc, instantaneous short circuit) has not occurred, and the current period determined by the period determination unit 22 Recognized as a normal arc period or a normal short circuit period. On the other hand, if the next period change occurs within a predetermined time, the instantaneous event determination unit 23 determines that the current period change and the previous period change are instantaneous events, and the period determination unit 22 The determined period is recognized as an instantaneous event. In addition, when the period after the instantaneous event is determined by the instantaneous event determination unit 23 is determined as a normal period, the normal period in which the current period determined by the period determination unit 22 continues from the normal period before the instantaneous event Recognized as

  Specifically, as shown in FIG. 2, the time t1 is measured for the predetermined time tx with respect to the times t1 to t6 at which the period change occurs, and the time t1 at which the period change does not occur within the predetermined time tx from the time t1. The period of t2 is a normal short circuit period, and the period of time t2 to t3 in which the period change occurs at time t3 within the predetermined time tx from time t2 is an instantaneous arc period. The change to the short-circuit period at the time t3 after the instantaneous arc is regarded as one short-circuit period that continues from the time t1 because no period change has occurred within the predetermined time tx. Similarly, the period from time t4 to t5 in which no period change has occurred within the predetermined time tx from time t4 is a normal arc period, and the period change has occurred at time t6 within the predetermined time tx from time t5. The period from time t5 to t6 is an instantaneous short circuit period. The change to the arc period at time t6 after the instantaneous short-circuit is regarded as one arc period continuing from time t4 because no period change has occurred within the predetermined time tx.

  The backup processing unit 24 backs up the control target value (internal calculation data) at the time when the period determination unit 22 determines the period change between the arc and the short circuit. That is, the backup processing unit 24 stores the control target value at the time of the short circuit period change in the memory 25 as the arc period backup data Dta as the latest control target value in the immediately preceding arc period, and performs control at the time of arc period change. The target value is stored in the memory 25 as short-circuit period backup data Dtb, assuming that the target value is the latest control target value in the immediately preceding short-circuit period. In this case, when it is determined by the instantaneous event determination unit 23 that an instantaneous event has occurred, the control target value used for output control is restored to appropriate control target value data before the instantaneous event (rollback processing). Is done.

  Specifically, in FIG. 2, at time t1, the short-circuit period change point, that is, the latest control target value data Dt1 of the arc period is stored as backup data Dta for arc period, and at time t2, the arc period change point, that is, the short-circuit period The latest control target value data Dt2 is stored as the short-circuit period backup data Dtb. At time t3, since it is determined as an instantaneous arc at the time of the short circuit period change, the control target value data Dt3 at time t3 is not held as the arc period backup data Dta, and the previous control target value data Dt1 is maintained. Further, as the use data Dx used for the output control immediately after the time t3 determined as the instantaneous arc, the control target value data Dt2 held as the short-circuit period backup data Dtb since the time t3 and after are the short-circuit period. Is used as the latest appropriate value data in the same short-circuit period.

  Similarly, at time t4, the control target value data Dt4 at the arc period change time (latest short-circuit period) is stored as short-circuit period backup data Dtb, and at time t5, the control target at the short-circuit period change time (latest arc period). Value data Dt5 is stored as arc period backup data Dta. At time t6, since it is determined as an instantaneous short circuit when the arc period changes, the control target value data Dt6 at time t6 is not retained as the short circuit period backup data Dtb, and the previous control target value data Dt4 is maintained. In addition, as the use data Dx for the output control immediately after the time t6 determined to be an instantaneous short circuit, the control target value data Dt5 held as the arc period backup data Dta is the same since the time t6 and later are the arc period. Used as the latest appropriate value data in the arc period. Incidentally, if the above method is used, even in a situation where instantaneous arcs or instantaneous short circuits occur continuously, the use data Dx for output control immediately after these instantaneous events becomes the latest appropriate value data for each arc period and short circuit period.

  Next, regarding the operation of the present embodiment, the control circuit 21 of the power supply device 11 calculates the control target value each time, and based on the calculated control target value, the inverter circuit 13, the auxiliary switching circuit 14, and the feeding device WF. Various controls are performed. Further, the control circuit 21 determines whether or not an instantaneous event such as an instantaneous arc or an instantaneous short-circuit occurs in addition to the determination of an arc period or a short-circuit period alternately generated during arc welding. When an instantaneous event occurs, the control circuit 21 does not use the control target value calculated each time for the control target value used for output control immediately after the instantaneous event determination, and backup data Dta and Dtb for each arc period and short-circuit period. The control target value stored as is used.

  As the backup data Dta and Dtb at this time, the latest appropriate control target value data immediately before the instantaneous event is stored for each normal arc period and short circuit period, and the data for each synchronization period is output control immediately after the instantaneous event. Therefore, immediately after the instantaneous event, control is not performed again as a new period start, but continuous control reflecting the output status before the instantaneous event is performed. Therefore, as shown in the specific example of FIG. 2, the mode of output control at the time t3 and the time t6 is continuous control. For example, the output current is quickly increased as shown by a dashed line in FIG. It is improved so that it rises and quickly recovers to the original output current value, which contributes to the stabilization of the subsequent output control.

Next, characteristic effects of the present embodiment will be described.
(1) When the period change occurs, the period determination unit 22 of the control circuit 21 determines whether it is an arc period or a short circuit period, and the instantaneous event determination unit 23 determines whether the instantaneous event (instantaneous event) It is determined whether the period is caused by arc or instantaneous short circuit. The backup processing unit 24 backs up the control target value every time the period changes, and holds the control target value immediately before the instantaneous event until it is determined that the instantaneous event has occurred. Based on the determination that an instantaneous event has occurred, the control circuit 21 performs output control based on the control target value immediately before the instantaneous event that has been backed up. That is, the control circuit 21 performs continuous output control with the instantaneous event interposed therebetween, and the control target value immediately after the instantaneous event is based on the control target value immediately before the instantaneous event. Since it is reflected, the control can be quickly restored to the original output value after any instantaneous event, and the stability of the output control after the instantaneous event can be improved.

  (2) The backup processing unit 24 backs up the control target values of the arc period and the short-circuit period as backup data Dta and Dtb, and the control circuit 21 immediately after the instantaneous event based on the determination that the instantaneous event has occurred. Output control is performed based on the control target value that has been backed up for the same period. Therefore, there is no confusion between periods, and appropriate output control can always be performed.

  (3) Since the backup processing unit 24 backs up the control target value only at the time of the period change, the load related to the backup process can be reduced, and the number of control target value data backups can be reduced.

  (4) Based on the determination that an instantaneous event has occurred, the control circuit 21 uses the control target value just backed up immediately before the instantaneous event as it is for output control. Thereby, when setting the control target value at the time of determination that an instantaneous event has occurred, the calculation in the control circuit 21 is unnecessary, and an increase in the calculation processing load can be prevented.

In addition, you may change embodiment of this invention as follows.
Although the control target value is backed up for each arc period and short circuit period, for example, the control target value may be backed up without being divided for each period. Further, although the control target value is backed up only at the time of the period change, the control target value data may be backed up at a timing other than the time of the period change.

  -In output control immediately after an instantaneous event, the control target value immediately before the instantaneous event that was backed up was used as it is, but for example, the influence of the instantaneous event should be canceled against the control target value immediately before the instantaneous event that was backed up. Data processing such as correction may be performed, and the control target value after the processing may be used. In this way, the output control immediately after the instantaneous event is performed in consideration of the influence of the instantaneous event, so that the stability of the output control immediately after the instantaneous event is further improved.

  -You may change the circuit structure of the power supply device 11 suitably. Although the inverter circuit 13 is composed of a full bridge circuit, it may be composed of another switching circuit such as a half bridge circuit. Further, the auxiliary switching circuit 14 may be omitted. Further, the secondary side output conversion circuit 15 is constituted by the rectifier circuit DR2, the DC reactor DCL, and the smoothing capacitor C3. However, the rectifier circuit DR2 may be replaced with another rectifier circuit, or the smoothing capacitor C3 may be omitted. Good.

DESCRIPTION OF SYMBOLS 10 Arc welding machine 11 Welding power supply device 21 Control circuit (control means)
22 Period determination unit (period determination means)
23 Instantaneous event determination unit (instantaneous event determination means)
24 Backup processing unit (backup processing means)

Claims (6)

A power supply device for welding used in a consumable electrode type arc welding machine in which an arc period and a short-circuit period are alternately generated, a control target value for performing output control including an output value at each period is calculated, and the control target A welding power supply device comprising a control means for performing output control based on a value,
The control means includes
A period determination means for determining whether an arc period or a short-circuit period when a period change occurs;
Instantaneous event determination means for determining whether a period has occurred due to an instantaneous event according to the relationship with the previous period change when a period change has occurred;
Backup control means for backing up the control target value every time the period changes, and backup processing means for holding at least the control target value immediately before the instantaneous event until it is determined that the instantaneous event has occurred, and the instantaneous event has occurred Based on the determination, output control is performed on the basis of the control target value immediately before the instantaneous event that has been backed up. In the welding power supply device according to claim 1,
The backup processing means backs up the control target values of the arc period and the short-circuit period,
The control means, based on the determination that the instantaneous event has occurred, performs output control based on the control target value that has been backed up in the same period as that immediately after the instantaneous event. Power supply. In the welding power supply device according to claim 1 or 2,
The welding power supply apparatus, wherein the backup processing means backs up the control target value only at the time of the period change. In the welding power supply device according to any one of claims 1 to 3,
The welding power supply apparatus according to claim 1, wherein the control means performs output control using the control target value immediately before the instantaneous event that has been backed up as it is based on the determination that the instantaneous event has occurred. In the welding power supply device according to any one of claims 1 to 3,
The control means performs correction so as to cancel the influence of the instantaneous event on the control target value immediately before the instantaneous event based on the determination that the instantaneous event has occurred, and after the correction A power supply apparatus for welding, wherein output control is performed using a control target value. It is a control method of a welding power source device used in a consumable electrode type arc welding machine in which an arc period and a short circuit period occur alternately, and calculates a control target value for performing output control including an output value at each period, A control method for a welding power source apparatus that performs output control based on the control target value,
When a period change occurs, determine whether it is an arc period or a short-circuit period,
When a period change occurs, determine whether it is a period caused by an instantaneous event based on the relationship with the previous period change,
Back up the control target value every time the period changes, and hold at least the control target value immediately before the instantaneous event until it is determined that the instantaneous event has occurred,
A control method for a welding power supply apparatus, wherein output control is performed based on a control target value immediately before the instantaneous event that has been backed up based on the determination that the instantaneous event has occurred.