JPWO2018220933A1 - Power supply device for arc processing and method of controlling power supply device for arc processing - Google Patents

Abstract

Driving and stopping of a plurality of inverter circuits (INV1, INV2) are controlled by the inverter circuits (INV1, INV2) according to the measured values of the temperatures of the switching elements constituting the inverter circuits (INV1, INV2) and the set values related to the output current. Select to reduce power consumption.

Description

  The present disclosure relates to a technique in which a plurality of inverter circuits built in an arc processing power supply device are provided in parallel and operated in parallel.

  In an arc processing power supply device, a plurality of inverter circuits have been provided in parallel in order to increase an output current as a welding current, and a parallel operation has been performed.

  On the other hand, in the arc processing power supply device provided with a plurality of inverter circuits as described above in parallel, particularly when the output current is small, it is better to stop some inverter circuits than to drive all inverter circuits. The weldability may be improved.

  In a conventional arc machining power supply device in which a plurality of inverter circuits are provided in parallel, a method is disclosed in which a pulse waveform of an output control signal of the inverter circuit is detected as missing and a certain inverter circuit is stopped. Patent Document 1).

Japanese Patent No. 4965238

  However, in the above-described conventional configuration, the power consumption of the arc processing power supply device as a whole may be increased by stopping a certain inverter circuit.

  The present disclosure provides a method of controlling an arc processing power supply device in which a plurality of inverter circuits are provided in parallel so as to reduce power consumption of the arc processing power supply device.

  An arc processing power supply device according to one embodiment of the present disclosure is an arc processing power supply device that performs short-circuit welding or pulse welding on an object to be welded, and rectifies commercial AC power and outputs a DC voltage. Secondary rectifier circuit, a first smoothing capacitor for smoothing the DC voltage output from the first primary rectifier circuit, and a first inverter for converting the DC voltage smoothed by the first smoothing capacitor into a high-frequency AC voltage A first main transformer for converting an output of the first inverter circuit into a high-frequency AC voltage suitable for arc machining; a first secondary rectifier circuit for rectifying an output of the first main transformer; A second primary rectifier circuit for rectifying commercial AC power and outputting a DC voltage, a second smoothing capacitor for smoothing the DC voltage output from the second primary rectifier circuit, and a second smoothing capacitor High frequency alternating current A second inverter circuit that converts the output of the second inverter circuit into a high-frequency AC voltage suitable for arc machining; and a second inverter that rectifies the output of the second main transformer. 2, a DC reactor for smoothing a current obtained by combining an output of the first secondary rectifier circuit and an output of the second secondary rectifier circuit and outputting an output current to an output terminal; An output current detection circuit for detecting the output current, an output current setting circuit for setting a set value related to a predetermined output current, and a first number for storing in advance the minimum number of inverter circuits that need to be driven corresponding to the output current. The storage circuit compares the set value of the output current set by the output current setting circuit with the minimum number of inverter circuits that need to be driven corresponding to the output current stored in the first storage circuit, Drive corresponding to the setting A comparison circuit for determining the minimum number of necessary inverter circuits, and a power consumption with respect to a temperature, which is a relationship between a temperature of a switching element included in the inverter circuit, an inverter output current per driven inverter circuit, and power consumption of the inverter circuit. , A set value related to the output current set by the output current setting circuit, a measured temperature of a switching element included in the first inverter circuit, and a second inverter. An arithmetic circuit for obtaining power consumption for a combination of driving and stopping each inverter circuit from a measured temperature of a switching element constituting the circuit and a power consumption parameter for the temperature stored in the second storage circuit; The minimum required number of inverter circuits that need to be driven in accordance with the And a first output for controlling the first inverter circuit based on the combination of the inverter circuits selected by the selection circuit. An output control circuit that outputs a control signal and a second output control signal that controls the second inverter circuit.

  According to another aspect of the present disclosure, there is provided a method for controlling a power supply device for arc processing, wherein a plurality of inverter circuits are provided in parallel, and a short-circuit welding having a welding start period, a main welding period, and a welding end period is performed on a workpiece. A method for controlling a power supply device for arc machining, wherein a main welding period of short-circuit welding includes a measurement value of a temperature of a switching element constituting an inverter circuit and a time average of an output current output to a workpiece. And calculating the power consumption in the combination of the operations of the respective inverter circuits from the average output current, and selecting the driving and stopping of the plurality of inverter circuits so as to minimize the sum of the power consumption in each of the plurality of inverter circuits. Is what you do.

  According to another aspect of the present disclosure, there is provided a control method of a power supply device for arc processing, wherein a plurality of inverter circuits are provided in parallel, and a pulse welding having a welding start period, a main welding period, and a welding end period with respect to a workpiece In the method for controlling the power supply device for arc processing, the main welding period of the pulse welding, for each of the inverter circuit from the measured value of the temperature of the switching element constituting the inverter circuit and the base current and peak current of the pulse welding And the operation of each of the plurality of inverter circuits is selected so as to minimize the total power consumption of the plurality of inverter circuits.

  A power supply device for arc machining according to an aspect of the present disclosure is a power supply device for arc machining that supports a large current and includes a plurality of power supply units connected in parallel. Each power supply unit includes a primary rectifier circuit, a smoothing capacitor, an inverter circuit, a main transformer, and a secondary rectifier circuit. The arc processing power supply device measures the temperatures of the switching elements constituting each of the inverter circuits, and determines whether to drive or stop each of the inverter circuits based on the measured temperatures of the switching elements. Therefore, the power consumption of the arc processing power supply device can be reduced.

FIG. 1 is an electrical connection diagram of a power supply device for arc processing in which two power supply units are provided in parallel. FIG. 2 shows an example of information stored in the first storage circuit in the arc processing power supply device in which two power supply units are provided in parallel, that is, the minimum number of inverter circuits that need to be driven corresponding to the output current. It is a figure showing an example of the relation of number. FIG. 3A is an example of information stored in a second storage circuit, that is, an example of a relationship between power consumption and temperature, in an arc processing power supply device provided with two power supply units in parallel, more specifically, an inverter. FIG. 7 is a diagram illustrating an example of a relationship between an inverter output current per one driven inverter circuit and power consumption of the inverter circuit at each circuit temperature. FIG. 3B is a diagram illustrating another example of the relationship between the power consumption and the temperature. FIG. 4 is a diagram illustrating an example of a calculation result of a calculation circuit in a power supply device for arc processing in which two power supply units are provided in parallel. FIG. 5 is a diagram illustrating an example of an output current waveform and an output voltage waveform during short-circuit welding. FIG. 6A is a diagram illustrating power consumption of the inverter circuits in a normal temperature region with respect to a combination of driving and stopping of each inverter circuit. FIG. 6B is a diagram illustrating power consumption of the inverter circuit in a high temperature region with respect to a combination of driving and stopping of each inverter circuit. FIG. 7 is a diagram illustrating a calculation result of the calculation circuit. FIG. 8 is a diagram showing an example of the relationship between the output current and the output voltage during short-circuit welding and the number of inverter circuits to be driven. FIG. 9 is a diagram illustrating an example of the relationship between the output current and the output voltage during short-circuit welding and the number of inverter circuits to be driven. FIG. 10 is a diagram illustrating an example of an output current waveform and an output voltage waveform during pulse welding. FIG. 11 is a diagram illustrating an example of the relationship between the output current and the output voltage during pulse welding and the number of inverter circuits to be driven.

(Embodiment 1)
Hereinafter, Embodiment 1 of the present disclosure will be described with reference to FIGS. 1 to 9. First, the configuration of the arc processing power supply device will be described with reference to FIGS. FIG. 1 shows an arc processing power supply device in which two power supply units each including a primary rectifier circuit, a smoothing capacitor, an inverter circuit, a main transformer, and a secondary rectifier circuit are provided in parallel.

  A DC power supply circuit is formed by a first primary rectifier circuit DR11 that rectifies AC power from the commercial AC power supply AC and outputs a DC voltage, and a first smoothing capacitor C1 that smoothes the DC voltage. Further, the second primary rectifier circuit DR12 and the second smoothing capacitor C2 are provided in parallel with the first primary rectifier circuit DR11, and respectively smooth the DC voltage with the first primary rectifier circuit DR11. The operation is the same as that of the first smoothing capacitor C1.

  The first inverter circuit INV1 is formed by a switching element such as an IGBT or a MOSFET. The first inverter circuit INV1 converts the DC voltage output by the first primary rectifier circuit DR11 into a high-frequency AC voltage and outputs it. Further, the second inverter circuit INV2 converts the DC voltage output by the second primary rectifier circuit DR12 into a high-frequency AC voltage and outputs it.

  The first main transformer MTR1 converts the high-frequency AC voltage output from the first inverter circuit INV1 into a high-frequency AC voltage suitable for arc machining. The first secondary rectifier circuit DR21 rectifies the output of the first main transformer MTR1 and outputs a DC current.

  The second main transformer MTR2 converts the high-frequency AC voltage output from the second inverter circuit INV2 into a high-frequency AC voltage suitable for arc machining. The second secondary rectifier circuit DR22 rectifies the output of the second main transformer MTR2 and outputs a DC current.

  The DC reactor DCL smoothes a DC current obtained by combining the DC current output from the first secondary rectifier circuit DR21 and the DC current output from the second secondary rectifier circuit DR22.

  Between the output terminal OT and the torch TH and between the output terminal OT and the workpiece M, wires and the like that can be electrically connected by an operator are attached. The output terminal OT supplies a DC current smoothed by the DC reactor DCL between the torch TH and the workpiece M as a welding current.

  The output current detection circuit CT detects an output current as a welding current, and outputs an output current detection signal Io indicating the detected output current. The output current is a DC current obtained by adding the DC current of the output of the first secondary rectifier circuit DR21 and the DC current of the output of the second secondary rectifier circuit DR22.

  The output current setting circuit IS outputs, as an output current setting signal Is, a set value related to an output current adjusted in advance by an operator.

  The first storage circuit MC1 stores in advance the relationship between the output current and the minimum number of inverter circuits that need to be driven. Here, the inverter circuits refer to the first inverter circuit INV1 and the second inverter circuit INV2. The first storage circuit MC1 outputs the stored relationship as a first storage signal Mc1. For example, as shown in FIG. 2, the first storage circuit MC1 stores the relationship of the minimum number of inverter circuits that need to be driven corresponding to the output current. When the output current has a current value smaller than the output current threshold Ith, it is necessary to drive at least one inverter circuit. When the output current is equal to or greater than the output current threshold Ith, it is necessary to drive at least two inverter circuits.

  The comparison circuit CC shown in FIG. 1 compares the output current setting signal Is with the first storage signal Mc1, and outputs the minimum number of inverter circuits that need to be driven as the comparison signal Cc.

  The second storage circuit MC2 stores the relationship between the power consumption of the inverter circuit and the temperature, and outputs this relationship as a second storage signal Mc2. More specifically, this relationship is a relationship between the inverter output current per one driven inverter circuit and the power consumption of the inverter circuit with respect to the temperature of the switching element forming the inverter circuit. For example, the second storage circuit MC2 stores the relationship between the inverter output current per driven inverter circuit and the power consumption of the inverter circuit with respect to temperature as shown in FIG. 3A. As is clear from the figure, as the output current per driven inverter circuit increases, the power consumption of the inverter circuit tends to increase. Further, when the temperature region is a high temperature of, for example, 80 to 90 ° C., the slope of the power consumption with respect to the inverter output current per one driven inverter circuit increases compared to the normal temperature of 5 to 35 ° C.

  Conversely, if the temperature region is high as shown in FIG. 3B, the slope of the power consumption with respect to the inverter output current per one driven inverter circuit may decrease compared to normal temperature. The relationship between the power consumption of the inverter circuit and the temperature stored in the second storage circuit MC2 is determined from the specifications of the switching elements (IGBT and MOSFET) constituting the first inverter circuit INV1 and the second inverter circuit INV2. it can.

  The first temperature measurement value T1 shown in FIG. 1 is a temperature measurement value of a switching element included in the first inverter circuit INV1. The second temperature measurement value T2 is a temperature measurement value of a switching element included in the second inverter circuit INV2. The temperatures of these switching elements are measured by a thermistor (not shown) or the like.

  The arithmetic circuit OC calculates the total power consumption of all inverter circuits for the combination of driving and stopping each inverter circuit. This total power consumption is obtained based on the first temperature measurement value T1, the second temperature measurement value T2, and the second storage signal Mc2. The operation circuit OC outputs this operation result as an operation signal Oc. For example, the calculation result of the power consumption by the combination of the inverter circuits by the calculation circuit OC is as shown in FIG. There are three combinations of driving and stopping the first inverter circuit INV1 and the second inverter circuit INV2 (excluding the case where both are stopped). The arithmetic circuit OC calculates the power consumption values W21, W22, W43 (W31 + W32) which are the total power consumption Ww3 in each case.

  Here, the power consumption value W21 is the value of the total power consumption when the first inverter circuit INV1 is driven and the second inverter circuit INV2 is stopped, that is, the value when the first inverter circuit INV1 is driven only one. This is the value of the total power consumption. Further, the power consumption value W22 is a value of the total power consumption when the first inverter circuit INV1 is stopped and the second inverter circuit INV2 is driven, that is, the value when the second inverter circuit INV2 is driven by only one. This is the value of the total power consumption. The power consumption value W43 is a value of the total power consumption when two inverter circuits are driven and both the first inverter circuit INV1 and the second inverter circuit INV2 are driven, that is, the first inverter circuit. This is the sum of the power consumption value W31 of INV1 and the power consumption value W32 of the second inverter circuit INV2.

  The selection circuit SC shown in FIG. 1 selects a combination that minimizes the total power consumption of the first inverter circuit INV1 and the second inverter circuit INV2 among combinations of the minimum number of inverter circuits that need to be driven or more. I do. This selection result is obtained based on the comparison signal Cc and the operation signal Oc. The selection circuit SC outputs a selection result regarding driving or stopping of each inverter circuit as a selection signal Sc.

  The output control circuit OCC controls the output of the inverter circuit whose driving is selected by the selection signal Sc so that the output current detection signal Io becomes equal to the output current setting signal Is. The output control circuit OCC further controls the output of the inverter circuit, the stop of which is selected by the selection signal Sc, to be 0. The output control circuit OCC outputs a first output control signal Occ1 for controlling the output of the first inverter circuit INV1 and a second output control signal Occ2 for controlling the output of the second inverter circuit INV2. .

  The first inverter drive circuit SD1 outputs a first inverter drive signal Sd1 for driving the first inverter circuit INV1 according to the first output control signal Occ1. Further, the second inverter drive circuit SD2 outputs a second inverter drive signal Sd2 for driving the second inverter circuit INV2 according to the second output control signal Occ2.

  As described above, in the arc machining power supply device having the configuration shown in FIG. 1, the first storage circuit MC1 stores the relationship of the minimum number of inverter circuits that need to be driven with respect to the output current shown in FIG. The second storage circuit MC2 stores the relationship between the temperature of the switching elements constituting the inverter circuit shown in FIG. 3A, the inverter output current per driven inverter circuit, and the power consumption of the inverter circuit.

  Next, the operation of short-circuit welding, which is short-circuit arc welding, will be described with reference to FIGS. The short-circuit welding includes a welding start period Th, a main welding period Tw, and a welding end period Te. The main welding period is a period in which the short-circuit period Ts in the short-circuit state and the arc period Ta in the arc state are repeated. In the following description, it is assumed that the first inverter circuit INV1 and the second inverter circuit INV2 are configured by the same switching element. The same switching element has the same type, in other words, a switching element having the same performance.

  FIG. 5 shows an output current waveform and an output voltage waveform during short-circuit welding. The main welding period Tw is a period in which welding is performed by moving the torch TH in accordance with a portion (weld line) where the workpiece M is to be welded. The average output current Iw is a time-averaged output current supplied between the welding wire and the workpiece M during the main welding period Tw, in other words, the output current output to the workpiece M. The average output current Iw corresponds to a set current as a set value of the output current during the main welding period Tw. The welding start period Th is a period in which a start current Ih higher than the average output current Iw of the main welding period Tw is output for a certain period of time to perform a process for facilitating the start of welding. The welding end period Te is a period in which a terminal current Ie lower than the average output current Iw of the main welding period Tw is output for a certain period of time to perform processing for preventing the welding wire and the workpiece M from sticking to each other. Basically, the worker adjusts the average output current Iw during the main welding period Tw and performs welding suitable for the workpiece M.

  As described above, the main welding period Tw of the short-circuit welding includes the short-circuit period Ts and the arc period Ta. The short-circuit period Ts is a period of a short-circuit state in which the welding wire and the workpiece M are in electrical contact (short-circuit). The arc period Ta is a period of an arc state in which a short circuit is released and an arc is generated. As shown in FIG. 5, the output voltage is low during the short circuit period Ts. On the other hand, in the arc period Ta, the output voltage increases and the output current decreases from a high current value. As described above, the output power during the main welding period in the short-circuit welding is constant to some extent, though there is some variation, if the set value of the average output current Iw is constant.

  Therefore, during the main welding period in short-circuit welding, the value of the average output current Iw set by the operator can be treated as the set value of the output current setting signal Is. When the set value of the average output current Iw is larger than the output current threshold value Ith (see FIG. 2) stored in the first storage circuit MC1, the comparison signal Cc indicates the drive of two inverter circuits. On the other hand, when the set value of the average output current Iw is smaller than the output current threshold Ith, the comparison signal Cc indicates the driving of at least one inverter circuit. In this case, the minimum number of inverter circuits to be driven changes according to the first temperature measurement value T1 and the second temperature measurement value T2.

  Here, a case where the set value of the average output current Iw is smaller than the output current threshold Ith will be described.

  For example, FIG. 3A shows the characteristics of the switching element of the inverter circuit in which the slope of the increase in power consumption is smaller in the normal temperature region than in the high temperature region. As the output current per inverter circuit increases, the power consumption of the inverter circuit also tends to increase. In addition, the slope of the increase in power consumption is smaller in the normal temperature region than in the high temperature region. In the normal temperature region, the rate of increase in power consumption is small even if the output current per driven inverter circuit increases.

  The high-temperature region is a temperature higher than the normal-temperature region and a temperature at which the switching element of the inverter circuit is not broken, for example, a temperature of 80 to 90 ° C. The normal temperature region is, for example, a temperature of 5 to 35 ° C.

  It is assumed that the first temperature measurement value T1 and the second temperature measurement value T2 are substantially the same before the start of welding, in which the inverter circuit of the arc processing power supply device is in a room temperature region where the temperature is sufficiently cooled. In this case, the relationship between the inverter output current and the power consumption of the inverter circuit is, for example, as shown in FIG. 6A. Since the temperature of the inverter circuit is in the normal temperature range, the slope of the increase in the power consumption of the inverter circuit with respect to the increase in the inverter output current per driven inverter circuit is small.

  FIG. 7 shows the calculation result of the power consumption in the combination pattern of the inverter circuits by the calculation circuit OC at this time. The arithmetic circuit OC calculates the total power consumption Ww3 of each of the combinations of driving and stopping the first inverter circuit INV1 and the second inverter circuit INV2. Specifically, the arithmetic circuit OC calculates the power consumption values Ww11, Ww12, Ww33 (Ww21 + Ww22) as the total power consumption Ww3.

  An inverter output current in the case where one of the first inverter circuit INV1 and the second inverter circuit INV2 is driven to supply the average output current Iw to the output terminal OT is referred to as an inverter output current I1. In addition, when the two inverter circuits of the first inverter circuit INV1 and the second inverter circuit INV2 are driven together to supply the average output current Iw to the output terminal OT, the inverter output current per inverter circuit is calculated. It is assumed that the inverter output current is I2. Here, there is a relationship that the inverter output current I1 is larger than the inverter output current I2. When two inverter circuits are driven together, the output of each inverter circuit is the same. In other words, the relationship is such that the inverter output current I1 is about twice the inverter output current I2.

  The power consumption value Ww11 is a value of the total power consumption when the first inverter circuit INV1 is driven and the second inverter circuit INV2 is stopped, that is, the total power consumption when only one first inverter circuit INV1 is driven. It is the value of power consumption. The power consumption value Ww12 is a value of the total power consumption when the first inverter circuit INV1 is stopped and the second inverter circuit INV2 is driven, that is, when only one second inverter circuit INV2 is driven. Is the value of the total power consumption. The inverter output current per inverter circuit when driven at the power consumption value Ww11 and the power consumption value Ww12 is the inverter output current I1.

  The power consumption value Ww33 is a power consumption value of the sum of the power consumption values of the respective inverter circuits when the two inverter circuits are both driven. That is, when both the first inverter circuit INV1 and the second inverter circuit INV2 are driven, the sum of the power consumption value Ww21 of the first inverter circuit INV1 and the power consumption value Ww22 of the second inverter circuit INV2 is consumed. It is the value of the power. The inverter output current per inverter circuit when driven at the power consumption value Ww21 and the power consumption value Ww22 is the inverter output current I2.

  Specifically, the inverter output current I1 is used to drive one of the first inverter circuit INV1 or the second inverter circuit INV2 to supply the average output current Iw to the output terminal OT. 5 is an inverter output current of the driven inverter circuit.

  The power consumption value Ww11 of the first inverter circuit INV1 is the value of the power consumption of the first inverter circuit INV1 when only the first inverter circuit INV1 supplies the average output current Iw to the output terminal OT.

  The power consumption value Ww12 of the second inverter circuit INV2 is a value of the power consumption of the second inverter circuit INV2 when only the second inverter circuit INV2 supplies the average output current Iw to the output terminal OT. Under the above conditions, the power consumption value Ww11 of the first inverter circuit INV1 and the power consumption value Ww12 of the second inverter circuit INV2 are substantially equal.

  The inverter output current I2 is an inverter output current per inverter circuit when two inverter circuits are driven together and an average output current Iw is supplied to the output terminal OT. The power consumption value Ww21 of the first inverter circuit INV1 is equal to the power consumption value Ww21 when the average output current Iw is supplied to the output terminal OT by the two inverter circuits including the first inverter circuit INV1 and the second inverter circuit INV2. 1 is a value of power consumption of the inverter circuit INV1.

  Further, the power consumption value Ww22 of the second inverter circuit INV2 is obtained when two inverter circuits including the first inverter circuit INV1 and the second inverter circuit INV2 supply the average output current Iw to the output terminal OT. Is the value of the power consumption of the second inverter circuit INV2. Under the above conditions, the power consumption value Ww21 of the first inverter circuit INV1 and the power consumption value Ww22 of the second inverter circuit INV2 are substantially equal.

  The power consumption value Ww33 is the sum of the two inverter circuits when the average output current Iw is supplied to the output terminal OT by the two inverter circuits including the first inverter circuit INV1 and the second inverter circuit INV2. Power consumption. The value is the sum of the power consumption value Ww21 of the first inverter circuit INV1 and the power consumption value Ww22 of the second inverter circuit INV2.

  Here, the total power consumption Ww3 of the calculation result of the calculation circuit OC for the combination of driving and stopping of each inverter circuit is as shown in FIG. In addition, the power consumption of the inverter circuit in the normal temperature region where the temperature of the switching element is low is as shown in FIG. 6A. In this case, for example, the combination of operations of the inverter circuit that reduces the power consumption of the inverter circuit during short-circuit welding is as follows.

  Specifically, power consumption value Ww33 is larger than power consumption value Ww11 and larger than power consumption value Ww12.

  Therefore, the selection circuit SC selects one inverter circuit in the normal temperature region and supplies the selection signal Sc for supplying the average output current Iw to the output terminal OT so that the power consumption of the arc processing power supply device is reduced. Is output.

  In this example, it is assumed that the first temperature measurement T1 and the second temperature measurement T2 are substantially equal. Therefore, when only one of the inverter circuits is driven alone, the power consumption value Ww11 of the first inverter circuit INV1 is substantially equal to the power consumption value Ww12 of the second inverter circuit INV2. However, the selection signal Sc is output so as to actually drive the smaller one of the inverter circuits.

  As a result, in the normal temperature region where the temperature of the switching element of the inverter circuit is low, the relationship between the inverter output current and the output voltage during short-circuit welding and the number of driven inverter circuits is as shown in FIG. In the main welding period Tw and the welding end period Te, one inverter circuit is driven, respectively. In the welding start period Th, the two inverter circuits are driven because the inverter output current becomes larger than the output current threshold value Ith.

  Further, for example, after one inverter circuit is driven during the main welding period Tw or the like, the temperatures of the switching elements forming the first inverter circuit INV1 and the second inverter circuit INV2 similarly rise and become high temperature regions. I do. In the case of the characteristics of the switching element shown in FIG. 3A, when the temperature of the switching element rises and becomes a high-temperature region, the slope of increase in power consumption with respect to the output current per one driven inverter circuit increases, in other words, the increase rate increases. Become.

  As described above, the temperature of the switching element of the inverter circuit becomes a high temperature region, and the relationship between the inverter output current per driven inverter circuit and the power consumption of the inverter circuit is higher than that in the normal temperature region as shown in FIG. 3A. The gradient of the power consumption increases in the region. In this case, the relationship between the inverter output current per inverter circuit and the power consumption of the inverter circuit in the high temperature region is as shown in FIG. 6B.

  Specifically, the power consumption value when one of the first inverter circuit INV1 and the second inverter circuit INV2 is driven is defined as a power consumption value (Ww11, Ww12). A power consumption value which is the sum of the respective power consumption values (Ww21, Ww22) when both of the inverter circuits are driven is referred to as a power consumption value Ww33. As shown in FIG. 6B, the increasing slope of the power consumption of the inverter circuit with respect to the inverter output current per driven inverter circuit is larger than the relationship in the normal temperature region shown in FIG. 6A.

  In the high temperature region, the total power consumption Ww3 of the calculation result of the calculation circuit OC for the combination pattern of driving and stopping each inverter circuit is as shown in FIG. The combination of the inverter circuits does not change from the normal temperature range before the temperature rises. In the case where the power consumption of the inverter circuit in the high temperature region where the temperature of the switching element is high has the relationship shown in FIG. 6B, for example, the following combinations of the operation of the inverter circuit in which the power consumption of the inverter circuit during short-circuit welding are reduced are as follows. Looks like

  Specifically, power consumption value Ww33 is smaller than power consumption value Ww11 or power consumption value Ww12.

  Therefore, the selection circuit SC outputs the selection signal Sc for driving the two inverter circuits together and supplying the average output current Iw to the output terminal OT so that the power consumption of the arc machining power supply device is reduced. I do.

  As a result, when welding is restarted in the high temperature region where the temperature has increased, the relationship between the output current and the output voltage and the number of driven inverter circuits at the time of short-circuit welding is as shown in FIG. 9, for example. In the main welding period Tw and the welding end period Te in which the temperature of the switching element is rising, two inverter circuits are driven. In the welding start period Th, the two inverter circuits are driven because the inverter output current becomes larger than the output current threshold value Ith.

  As described above, the arc machining power supply device of the present embodiment includes the inverter circuits (INV1, INV2) provided in parallel and performs short-circuit welding on the workpiece M. The short-circuit welding has a welding start period Th, a main welding period Tw, and a welding end period Te. During the main welding period Tw of the short-circuit welding, the arc processing power supply device outputs the measured temperature values (T1, T2) of the switching elements constituting the inverter circuits (INV1, INV2) and the welding output to the workpiece M. From the average output current Iw which is the time average of the output current as the current, the power consumption in the combination of the driving and the stopping operation of each inverter circuit (INV1, INV2) is calculated. Further, the power supply device for arc processing selects driving and stopping of each of the plurality of inverter circuits so that the total power consumption Ww3, which is the sum of the power consumption of the plurality of inverter circuits (INV1, INV2), is minimized.

  This makes it possible to reduce the power consumption of the inverter circuits (INV1, INV2) constituting the arc processing power supply device during the main welding period Tw of the short-circuit welding.

(Embodiment 2)
Next, Embodiment 2 of the present disclosure will be described with reference to FIGS. 1 to 3A and FIGS. 10 to 11.

  The configuration of the power supply device for arc machining of the second embodiment is the same as that of the first embodiment. In the arc machining power supply device having the configuration shown in FIG. 1, the first storage circuit MC1 stores the relationship between the minimum number of inverter circuits that need to be driven and the inverter output current shown in FIG. The second storage circuit MC2 stores the relationship between the temperature of the switching elements constituting the inverter circuit shown in FIG. 3A, the inverter output current per driven inverter circuit, and the power consumption of the inverter circuit. The first inverter circuit INV1 and the second inverter circuit INV2 are configured by the same switching element. The operation of pulse welding will be described with reference to FIGS. The pulse welding includes a main welding period in which a base period Tb and a peak period Tp are repeated. The power supply device for arc processing outputs a base current Ib having a low output current value during the base period Tb, and outputs a peak current Ip having a high output current value during the peak period Tp.

  FIG. 10 shows an output current waveform and an output voltage waveform during pulse welding. In FIG. 5, those having the same reference numerals for the output current waveform and the output voltage waveform at the time of short-circuit welding shown in FIG. 5 have the same meaning, and therefore the description thereof will be omitted, and only those having different reference numerals will be described.

  In the pulse welding, a base period Tb having a low output current value and a peak period Tp having a high output current value are regularly and alternately present in the main welding period Tw. The base current Ib represents an output current value during the base period Tb, and the peak current Ip represents an output current value during the peak period Tp.

  In general, the arc processing power supply device performs a certain calculation based on the average output current Iw set by the operator to determine a base current Ib and a peak current Ip. However, in order to further improve the weldability, the operator can directly adjust the base current Ib and the peak current Ip.

  Pulse welding has less contact (short circuit) between the welding wire and the workpiece M as compared with short circuit welding. In the base period Tb, both the output current and the output voltage are low, and in the peak period Tp, both the output current and the output voltage are high. Therefore, a small amount of power is required in the base period Tb, but a large amount of power is required in the peak period Tp. In pulse welding, the output power fluctuates greatly during the main welding period.

  Therefore, in the main welding period Tw in pulse welding, the value of the base current Ib is treated as the set value of the output current setting signal Is in the base period Tb, and the value of the peak current Ip is set in the output current setting signal Is in the peak period Tp. It is treated as a setting value.

  In this embodiment, the relationship between the output current threshold value Ith of pulse welding, the base current Ib, and the peak current Ip stored in the first storage circuit MC1 is as shown in FIGS. In the peak period Tp of the peak current Ip requiring large power, the comparison signal Cc indicates the driving of the two inverter circuits. Therefore, the arc processing power supply device drives the two inverter circuits and outputs the peak current Ip.

  In the base period Tb requiring less power than the peak period Tp, the comparison signal Cc indicates the driving of at least one inverter circuit. Further, as described in the first embodiment, the first inverter circuit INV1 and the second inverter circuit INV1 are determined based on the relationship between the temperature based on the first temperature measurement value T1 and the second temperature measurement value T2 and the power consumption with respect to this temperature. The drive or stop of the inverter circuit INV2 is selected. The arc processing power supply device drives one or two inverter circuits to output a base current Ib.

  An example of the relationship between the output current and the output voltage in pulse welding and the number of driven inverter circuits will be specifically described with reference to FIG. The figure shows an example in which one inverter is driven in the first to third base periods Tb, and two inverters are driven in the fourth base period Tb. As time passes, the temperature of the switching elements forming the inverter circuit rises. As described above, when the temperature of the switching element is in the high-temperature region, the total power consumption may be smaller when two inverter circuits are driven than when one inverter circuit is driven. In the example of FIG. 11, in the first to third base periods Tb, the arithmetic circuit OC determines that driving one inverter circuit can reduce power consumption compared to driving two inverter circuits. . Therefore, the selection circuit SC selects the driving of one inverter circuit. On the other hand, in the fourth base period Tb, the arithmetic circuit OC determines that the power consumption is smaller when driven by two inverter circuits than when driven by one inverter circuit. Therefore, the selection circuit SC selects the driving of the two inverter circuits.

  As described above, the arc machining power supply device of the present embodiment includes a plurality of inverter circuits provided in parallel, and performs pulse welding on the workpiece M. The pulse welding has a welding start period Th, a main welding period Tw, and a welding end period Te. For the main welding period Tw of the pulse welding, the power supply device for arc processing uses the temperature measurement values (T1, T2) of the switching elements constituting the inverter circuits (INV1, INV2) and the base current and the peak current of the pulse welding for each. The power consumption in the combination of the driving and stopping operations of the inverter circuits (INV1, INV2) is calculated. Further, the arc processing power supply device selects driving and stopping of each of the plurality of inverter circuits so that the total power consumption of the plurality of inverter circuits (INV1 and INV2) is minimized.

  This makes it possible to reduce the power consumption of the inverter circuits (INV1, INV2) constituting the power supply device for arc machining during the main welding period Tw of the pulse welding.

(Embodiment 3)
Next, a third embodiment of the present disclosure will be described with reference to FIGS. 1 to 3A, FIG. 5, and FIGS.

  The configuration of the arc machining power supply device of the third embodiment is the same as that of the first embodiment. In the arc machining power supply device having the configuration shown in FIG. 1, the first storage circuit MC1 stores the relationship of the minimum number of inverter circuits that need to be driven with respect to the output current as shown in FIG. The second storage circuit MC2 stores the relationship between the temperature of the switching elements constituting the inverter circuit as shown in FIG. 3A, the inverter output current per driven inverter circuit, and the power consumption of the inverter circuit. The first inverter circuit INV1 and the second inverter circuit INV2 are configured by the same switching element. The operation during the welding start period will be described with reference to FIGS. 5, 10, and 11.

  As can be seen from FIGS. 5 and 10, in both the short-circuit welding and the pulse welding, the welding start period Th outputs a start current Ih higher than the average output current Iw during the main welding period for a certain period of time. Process to make it easier to start.

  Generally, the arc processing power supply device performs a predetermined calculation based on the average output current Iw set by the operator to determine the start current Ih. However, in order to further improve the weldability, the operator can directly adjust the start current Ih.

  Therefore, for the welding start period Th, the value of the start current Ih is treated as the set value of the output current setting signal Is.

  When the start current Ih is higher than the output current threshold Ith, the comparison signal Cc indicates the driving of two inverter circuits. Therefore, as shown in FIG. 8, FIG. 9, and FIG. 11, the arc machining power supply device drives the two inverter circuits to output the start current Ih.

  As described above, in the arc machining power supply device of the present embodiment, for the welding start period Th, the temperature measurement values (T1, T2) of the switching elements included in the inverter circuits (INV1, INV2) and the main welding period Tw And the constant start current Ih and the power consumption in each of the inverter circuits (INV1, INV2). Further, the arc processing power supply device selects driving and stopping of the inverter circuits (INV1, INV2) such that the total power consumption Ww3, which is the total power consumption of the plurality of inverter circuits, is minimized. The constant start current Ih may be higher than the average output current Iw.

  Although the start current Ih used for calculating the power consumption in the inverter circuits (INV1, INV2) is a constant start current Ih, it may be an average start current Ihw. The average start current Ihw is a current obtained by time-averaging the output current during the welding start period Th. The average start current Ihw may be higher than the average output current Iw.

  Thereby, power consumption in the inverter circuits (INV1, INV2) constituting the arc processing power supply device during the welding start period Th can be reduced.

(Embodiment 4)
Next, a fourth embodiment of the present disclosure will be described with reference to FIGS. 1 to 3A, FIG. 5, and FIGS. 8 to 11.

  The configuration of the arc machining power supply device of the fourth embodiment is the same as that of the first embodiment. In the arc machining power supply device having the configuration shown in FIG. 1, the first storage circuit MC1 stores the relationship of the minimum number of inverter circuits that need to be driven with respect to the output current as shown in FIG. The second storage circuit MC2 stores the relationship between the temperature of the switching elements constituting the inverter circuit, the output current per inverter circuit, and the power consumption of the inverter circuit as shown in FIG. 3A. The first inverter circuit INV1 and the second inverter circuit INV2 are configured by the same switching element. The operation in the welding end period will be described with reference to FIGS.

  In both the short-circuit welding and the pulse welding, as can be seen from FIGS. 5 and 10, in the welding end period Te, a welding wire that outputs a terminal current Ie lower than the average output current Iw during the main welding period for a certain period of time. And the workpiece M are prevented from sticking to each other.

  In general, the arc processing power supply device performs a predetermined calculation based on the average output current Iw set by the operator to determine the terminal current Ie. However, in order to further improve the weldability, the operator can directly adjust the termination current Ie.

  Therefore, for the welding end period Te, the value of the termination current Ie is treated as the set value of the output current setting signal Is.

  When the termination current Ie is lower than the output current threshold Ith, the comparison signal Cc indicates the driving of at least one inverter circuit. As described in the first embodiment, the arc processing power supply device uses the first temperature measurement value T1 and the second temperature measurement value T2 based on the relationship between the temperature of the inverter circuit and the power consumption. Driving or stopping of INV1 and the second inverter circuit INV2 is selected. The arc machining power supply device drives the selected inverter circuit to output the termination current Ie. 8 and 11 show examples in which the termination current Ie is output by one inverter circuit. FIG. 9 shows an example in which the termination current Ie is output by two inverter circuits.

  As described above, in the arc machining power supply device of the present embodiment, the temperature measurement values (T1, T2) of the switching elements included in the inverter circuits (INV1, INV2) and the constant termination current Ie for the welding end period Te. Then, the power consumption in the combination of the operations of the respective inverter circuits (INV1, INV2) is calculated. Further, the arc processing power supply device selects driving and stopping of each of the plurality of inverter circuits so that the total power consumption Ww3 which is the sum of the power consumption of the plurality of inverter circuits (INV1 and INV2) is minimized. The constant termination current Ie may be lower than the average output current Iw. Although the termination current Ie used to calculate the power consumption in the inverter circuits (INV1, INV2) is a constant termination current Ie lower than the average output current Iw, the average termination current Ie is lower than the average output current Iw. Iew may be used. The average termination current Iew is a current obtained by time-averaging the output current in the welding end period Te. The average termination current Iew may be lower than the average output current Iw.

  This makes it possible to reduce power consumption in the inverter circuits (INV1, INV2) constituting the arc processing power supply during the welding end period Te.

  As described above in detail in Embodiments 1 to 4, the technology of the present disclosure reduces power consumption by setting an appropriate output current setting signal Is in advance according to a welding method and a welding period. Can be achieved. Further, depending on any combination of the first to fourth embodiments, power consumption can be reduced in the entire welding period including the welding start period, the main start period, and the welding end period.

  The arc processing power supply device according to the present disclosure can drive or stop a plurality of inverter circuits by a measured value of a temperature of a switching element included in the inverter circuit and a set value related to an output current. It is industrially useful because it can be selected as follows.

AC commercial AC power supply C1 first smoothing capacitor C2 second smoothing capacitor CC comparison circuit Cc comparison signal CT output current detection circuit DCL DC reactor DR11 first primary rectifier circuit DR12 second primary rectifier circuit DR21 first Secondary rectifier circuit DR22 Second secondary rectifier circuit I1, I2 Inverter output current Ib Base current Ie Termination current Iew Average termination current Ih Start current Ihw Average start current INV1 First inverter circuit INV2 Second inverter circuit Io Output current Detection signal Ip Peak current IS Output current setting circuit Is Output current setting signal Ith Output current threshold Iw Average output current M Workpiece MC1 First storage circuit Mc1 First storage signal MC2 Second storage circuit Mc2 Second storage Signal MTR1 first main transformer MTR2 second Transformer OC operation circuit Oc operation signal OCC output control circuit Occ1 first output control signal Occ2 second output control signal OT output terminal SC selection circuit Sc selection signal SD1 first inverter drive circuit Sd1 first inverter drive signal SD2 Second inverter drive circuit Sd2 Second inverter drive signal T1 First temperature measured value T2 Second temperature measured value Ta Arc period Tb Base period Te Welding end period TH Torch Th Welding start period Tp Peak period Ts Short circuit period Tw Main welding period W21, W22, W31, W32, W43 Power consumption value Ww11, Ww12, Ww21, Ww22, Ww33 Power consumption value Ww3 Total power consumption

Claims (9)

An arc processing power supply device for performing short-circuit welding or pulse welding on an object to be welded,
A first primary rectifier circuit that rectifies commercial AC power and outputs a DC voltage;
A first smoothing capacitor for smoothing a DC voltage output from the first primary rectifier circuit;
A first inverter circuit for converting a DC voltage smoothed by the first smoothing capacitor into a high-frequency AC voltage;
A first main transformer for converting an output of the first inverter circuit into a high-frequency AC voltage suitable for arc machining;
A first secondary rectifier circuit for rectifying an output of the first main transformer;
A second primary rectifier circuit that rectifies the commercial AC power and outputs a DC voltage;
A second smoothing capacitor for smoothing the DC voltage output from the second primary rectifier circuit;
A second inverter circuit that converts the DC voltage smoothed by the second smoothing capacitor into a high-frequency AC voltage;
A second main transformer for converting an output of the second inverter circuit into a high-frequency AC voltage suitable for arc machining;
A second secondary rectifier circuit for rectifying the output of the second main transformer;
A DC reactor that smoothes a current obtained by combining an output of the first secondary rectifier circuit and an output of the second secondary rectifier circuit and outputs an output current to an output terminal;
An output current detection circuit that detects the output current;
An output current setting circuit for setting a set value related to a predetermined output current,
A first storage circuit that stores in advance a minimum number of inverter circuits that need to be driven corresponding to the output current;
Comparing the set value of the output current set by the output current setting circuit with the minimum number of inverter circuits that need to be driven corresponding to the output current stored in the first storage circuit, A comparison circuit that determines the minimum number of inverter circuits that need to be driven,
A second storage circuit for storing in advance a relationship between power consumption with respect to temperature, which is a relationship between a temperature of a switching element included in the inverter circuit, an inverter output current per driven inverter circuit, and power consumption of the inverter circuit; A set value related to the output current set by the output current setting circuit,
The measured temperature of the switching element that forms the first inverter circuit, the measured temperature of the switching element that forms the second inverter circuit, and the temperature stored in the second storage circuit. An arithmetic circuit for calculating power consumption for a combination of driving and stopping each inverter circuit from a relationship of power consumption;
A selection circuit for selecting a combination of inverter circuits that requires the least power consumption among the power consumptions determined by the arithmetic circuit, with a minimum number of inverter circuits that need to be driven corresponding to the setting determined by the comparison circuit. When,
An output for outputting a first output control signal for controlling the first inverter circuit and a second output control signal for controlling the second inverter circuit based on a combination of the inverter circuits selected by the selection circuit; And a control circuit. The short-circuit welding has a welding start period, a main welding period, and a welding end period, and outputs an average output current that is a time average of an output current output to the workpiece during the main welding period. The power supply device for arc machining according to claim 1, wherein the power supply device is a set value related to an electric current. The arc according to claim 1, wherein the pulse welding includes a welding start period, a main welding period, and a welding end period, and for the main welding period, a base current value and a peak current value are set values related to an output current. Power supply for processing. 4. The power supply device for arc processing according to claim 2, wherein in the welding start period, a welding start current value for starting welding is set as a set value related to an output current. 5. 4. The arc processing power supply device according to claim 2, wherein, for the welding end period, a welding end current value used for terminating welding is set as a set value related to an output current. A plurality of inverter circuits are provided in parallel, a welding start period, a main welding period, and a control method of a power supply device for arc processing that performs short-circuit welding having a welding end period for a workpiece.
For the main welding period of the short-circuit welding, each of the measured value of the temperature of the switching element constituting the inverter circuit and the average output current that is a time average of the output current output to the workpiece to be welded. Calculate power consumption in a combination of operations of the inverter circuit,
A method of controlling a power supply device for arc machining, wherein the driving and stopping of each of the plurality of inverter circuits are selected so that the total power consumption of the plurality of inverter circuits is minimized. A plurality of inverter circuits are provided in parallel, a welding start period, a main welding period, and a control method of an arc processing power supply device that performs pulse welding having a welding end period for an object to be welded,
For the main welding period of the pulse welding, the power consumption in each combination of the operations of the inverter circuits is calculated from the measured value of the temperature of the switching element constituting the inverter circuit and the base current and the peak current of the pulse welding. And
A method of controlling a power supply device for arc machining, wherein the driving and stopping of each of the plurality of inverter circuits are selected so that the total power consumption of the plurality of inverter circuits is minimized. For the welding start period, the measured value of the temperature of the switching element constituting the inverter circuit, and a constant start current or an average start current obtained by time-averaging the output current during the welding start period, the operation of each inverter circuit. Calculate the power consumption in the combination,
8. The control method for an arc machining power supply device according to claim 6, wherein driving and stopping of each of the plurality of inverter circuits are selected so that the total power consumption of the plurality of inverter circuits is minimized. For the welding end period, the operation value of each of the inverter circuits is determined from a measured value of the temperature of the switching element constituting the inverter circuit and a constant terminal current or an average terminal current obtained by time-averaging the output current during the welding end period. Calculate the power consumption in the combination,
8. The control method for an arc machining power supply device according to claim 6, wherein driving and stopping of each of the plurality of inverter circuits are selected so that the total power consumption of the plurality of inverter circuits is minimized.

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