JP2021114807A - Arc machining power source device - Google Patents

Abstract

To provide an arc machining power source device which is used for both of a single phase and three-phase, and enables a power factor thereof to be improved at a single phase operation.SOLUTION: A weld power source device A1 comprises: a rectification circuit 1; a power-factor improvement circuit 2; an inverter circuit; and a power-factor improvement circuit 8 controlling the power-factor improvement circuit 2, and outputs a power for generating an arc. The power-factor improvement circuit 8 comprises: a drive signal generation unit (a PFC control IC84 and a drive circuit 86) generating a drive signal on the basis of an output voltage of the power-factor improvement circuit 2; and a determination circuit 81 that determines whether or not a three-phase AC power is input into the rectification circuit 1 or a single-phase AC power is input. The power-factor improvement circuit 8 inputs the drive signal into the power-factor improvement circuit 2 at a single-phase operation, and inputs the drive signal into the power-factor improvement circuit 2 from an input start of the three-phase AC power until when the output voltage becomes a first voltage or more. After the output voltage becomes the first voltage or more, the power-factor improvement circuit 8 stops the output of the drive signal.SELECTED DRAWING: Figure 1

Description

The present invention relates to a single-phase / three-phase combined arc processing power supply device.

A single-phase welding power supply device to which single-phase AC power is input is equipped with a power factor correction (PFC) circuit between the rectifier circuit and the inverter circuit to improve the power factor. There is. Patent Document 1 discloses a single-phase welding power supply device including a power factor improving circuit. On the other hand, the three-phase welding power supply device to which the three-phase AC power is input does not have a power factor improving circuit because the power factor of the DC power after rectification is relatively high (for example, about 80%). Patent Document 2 discloses a three-phase welding power supply device. The three-phase welding power supply device rectifies the input three-phase AC power with a three-phase full-wave rectifier circuit, smoothes it with an input reactor and a smoothing capacitor, and outputs it to an inverter circuit. In addition, a single-phase / three-phase welding power supply device has been developed that enables the input of single-phase AC power to the three-phase welding power supply device.

Japanese Unexamined Patent Publication No. 2000-5874 Japanese Unexamined Patent Publication No. 2019-205264

The single-phase / three-phase combined welding power supply device does not have a power factor improvement circuit because the three-phase welding power supply device can also input single-phase AC power. Therefore, the single-phase / three-phase combined welding power supply device inputs DC power to the inverter circuit in a state where the power factor is not improved during single-phase operation in which single-phase AC power is input. Therefore, the distribution equipment that supplies the single-phase AC power to the welding power supply device needs to have a larger capacity than the case where the single-phase AC power is supplied to the single-phase welding power supply device. This problem is not limited to the welding power supply device, but becomes a problem in the arc processing power supply device that processes by the generated arc.

The present invention has been conceived under the above circumstances, and provides an arc processing power supply device for both single-phase and three-phase, which can improve the power factor during single-phase operation. The purpose is to do.

The arc processing power supply device provided by the present invention is a rectifying circuit in which three-phase AC power or single-phase AC power is input and outputs DC power, and a boost-type chopper circuit having a switching element, from the rectifying circuit. A power factor improvement circuit that improves the power factor of the input DC power, an inverter circuit that converts the DC power input from the power factor improvement circuit into high-frequency power, and a power factor improvement control that controls the power factor improvement circuit. A drive signal generation that includes a circuit, outputs electric power for generating an arc, and generates a drive signal for driving the switching element based on the output voltage of the power factor improvement circuit. A unit and a discriminating circuit for discriminating whether a three-phase AC power is input or a single-phase AC power is input to the rectifying circuit, and when the discriminating circuit determines that the single-phase AC power is input. When the drive signal is input to the switching element and it is determined that the three-phase AC power has been input, the above is described from the start of input of the three-phase AC power until the output voltage becomes the first voltage or higher. The drive signal is input to the switching element, and after the output voltage becomes equal to or higher than the first voltage, the output of the drive signal is stopped.

In a preferred embodiment of the present invention, the power factor improvement control circuit is described until the output voltage becomes the third voltage or more when the output voltage becomes the second voltage or less after the output voltage becomes the first voltage or more. The drive signal is input to the switching element.

In a preferred embodiment of the present invention, the force factor improvement control circuit discriminates between a comparison circuit for comparing the output voltage and the first voltage, a signal indicating a comparison result of the comparison circuit, and the discrimination circuit. It further includes an OR circuit that outputs a logical sum signal with a signal indicating a result, and an AND circuit that switches between output and stop of the drive signal according to the logical sum signal.

In a preferred embodiment of the present invention, the drive signal generator is driven for a continuous current mode based on the current flowing through the power factor improving circuit and the input and output voltages of the power factor improving circuit. Generate a signal.

In a preferred embodiment of the present invention, welding is performed by an arc generated by the output electric power.

According to the present invention, the power factor improvement control circuit uses the drive signal generated by the drive signal generator as the switching element of the power factor improvement circuit when it is determined by the discrimination circuit that the single-phase AC power has been input. By inputting, the power factor improvement circuit is operated. Therefore, the arc processing power supply device according to the present invention can improve the power factor during single-phase operation. Further, in the power factor improvement control circuit, when it is determined by the discrimination circuit that the three-phase AC power has been input, the output voltage of the power factor improvement circuit becomes the first voltage or higher from the start of the input of the three-phase AC power. Until then, the power factor improvement circuit is operated by inputting the drive signal to the switching element, and after the output voltage becomes the first voltage or higher, the power factor improvement circuit is operated by stopping the output of the drive signal. To stop. As a result, the arc processing power supply device according to the present invention can prevent a sudden rise in the output voltage at the initial start of input of the three-phase AC power during the three-phase operation, and can suppress an unnecessary power factor improving operation.

It is a block diagram which shows the whole structure of the welding power supply device which concerns on 1st Embodiment. (A) is a circuit diagram showing an example of the internal configuration of the comparison circuit, and (b) is a block diagram showing an example of the internal configuration of the PFC control IC. It is a time chart for explaining the change of each voltage and the change of the power factor improvement drive signal at the time of three-phase operation. It is a block diagram which shows the internal structure of the power factor improvement control circuit of the welding power supply device which concerns on 2nd Embodiment. It is a block diagram which shows the internal structure of the power factor improvement control circuit of the welding power supply device which concerns on 3rd Embodiment.

Hereinafter, preferred embodiments of the present invention will be specifically described with reference to the accompanying drawings, taking as an example the case where the present invention is applied to a welding power supply device.

[First Embodiment]
FIG. 1 is a block diagram showing an overall configuration of the welding power supply device A1 according to the first embodiment. The welding power supply device A1 supplies electric power to the welding torch T and the base metal W in order to generate an arc in the arc welding system. The welding power supply device A1 is supplied with AC power from a power distribution facility (not shown), converts it into DC power suitable for arc welding, and outputs it. The welding power supply device A1 is a single-phase / three-phase combined welding power supply device, and single-phase AC power or three-phase AC power is input from the power distribution facility. The welding power supply device A1 is provided with three input terminals u, v, w, and when three-phase AC power is input, one of the three phases is provided for each of the three input terminals u, v, w. The AC power of the phase is input. On the other hand, in the welding power supply device A1, when single-phase AC power is input, AC power is input to the input terminals u and v. Therefore, no voltage is applied between the input terminal v and the input terminal w. Further, the welding power supply device A1 includes output terminals a and b. The output terminal a is connected to the electrode of the welding torch T, and the output terminal b is connected to the base material W. The arc welding system in which the welding power supply device A1 is used is not limited, and may be a semi-automatic welding system, a fully automatic welding system by a robot, a shielded metal arc welding system, or the like. The welding power supply device A1 includes a rectifier circuit 1, a power factor improvement circuit 2, an inverter circuit 3, a transformer 4, a rectifier circuit 5, a current sensor 6, an inverter control circuit 7, and a power factor improvement control circuit 8.

The rectifier circuit 1 converts commercial frequency AC power input from the distribution equipment into DC power and outputs it. The rectifier circuit 1 includes a three-phase full-wave rectifier circuit and a smoothing capacitor. The configuration of the rectifier circuit 1 is not limited. The rectifier circuit 1 can convert and output DC power regardless of whether three-phase AC power is input from the input terminals u, v, w or single-phase AC power is input from the input terminals u, v, v. It should be. The rectifier circuit 1 corresponds to the "rectifier circuit" of the present invention.

The power factor improving circuit 2 improves the power factor of the DC power input from the rectifier circuit 1 and outputs it to the inverter circuit 3. The power factor improvement circuit 2 switches the power factor of DC power described later by switching the switching element 21 described later in response to the drive signal (power factor improvement drive signal P described later) input from the power factor improvement control circuit 8. Improve. In the present embodiment, the power factor improving circuit 2 is a step-up chopper circuit, and includes a switching element 21, a reactor 22, a diode 23, a smoothing capacitor 24, and a discharge resistor 25.

One terminal of the reactor 22 is connected to the output terminal on the positive electrode side of the rectifier circuit 1. In the diode 23, the anode terminal is connected to the other terminal of the reactor 22, and the cathode terminal is connected to the input terminal on the positive electrode side of the inverter circuit 3. The switching element 21 is connected between the connection point between the reactor 22 and the diode 23 and the connection line connecting the output terminal on the negative electrode side of the rectifier circuit 1 and the input terminal on the negative electrode side of the inverter circuit 3. In this embodiment, the switching element 21 is a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The switching element 21 may be an IGBT (Insulated Gate Bipolar Transistor), a bipolar transistor, or the like. The smoothing capacitor 24 and the discharge resistor 25 are connected in parallel between the input terminal on the positive electrode side and the input terminal on the negative electrode side of the inverter circuit 3. As is clear from FIG. 1, the power factor improving circuit 2 is a capacitor input type rectifier circuit when the switching element 21 does not switch (when the off state continues). The circuit configuration of the power factor improving circuit 2 is not limited.

Further, the power factor improvement circuit 2 includes an input voltage detection unit 26, an output voltage detection unit 27, and a current detection unit 28 in order to detect a signal input to the power factor improvement control circuit 8. The input voltage detection unit 26 is a voltage dividing circuit in which two resistors are connected in series, and is arranged between an output terminal on the positive electrode side and an output terminal on the negative electrode side of the rectifier circuit 1. The input voltage detection unit 26 detects the input voltage detection signal Vi corresponding to the voltage input to the power factor improvement circuit 2 and inputs it to the power factor improvement control circuit 8. The output voltage detection unit 27 is a voltage dividing circuit in which two resistors are connected in series, and is arranged between an input terminal on the positive electrode side and an input terminal on the negative electrode side of the inverter circuit 3. The output voltage detection unit 27 detects the output voltage detection signal Vo corresponding to the voltage output from the power factor improvement circuit 2 and inputs it to the power factor improvement control circuit 8. The current detection unit 28 is a shunt resistor and is arranged on a connection line connecting the output terminal on the negative electrode side of the rectifier circuit 1 and the input terminal on the negative electrode side of the inverter circuit 3. The current detection unit 28 detects the current detection signal I corresponding to the current flowing through the power factor improvement circuit 2 and inputs it to the power factor improvement control circuit 8. The configurations of the input voltage detection unit 26, the output voltage detection unit 27, and the current detection unit 28 are not limited.

The inverter circuit 3 is, for example, a single-phase full-bridge type PWM control inverter and includes four switching elements. The inverter circuit 3 switches each switching element according to the output control drive signal input from the inverter control circuit 7, thereby converting the DC power input from the power factor improving circuit 2 into high frequency power and outputting it. The inverter circuit 3 may be of any type as long as it converts DC power into high-frequency power, and may be, for example, a half-bridge type or an inverter circuit having another configuration.

The transformer 4 transforms the high-frequency voltage output by the inverter circuit 3 and outputs it to the rectifier circuit 5. The transformer 4 includes a primary winding and a secondary winding. Each input terminal of the primary winding is connected to each output terminal of the inverter circuit 3. Each output terminal of the secondary winding is connected to each input terminal of the rectifier circuit 5. The output voltage of the inverter circuit 3 is transformed according to the turns ratio of the primary winding and the secondary winding, and is input to the rectifier circuit 5. Since the secondary winding is insulated from the primary winding, it is possible to prevent the current input from the distribution equipment from flowing to the secondary circuit. Further, since the transformer 4 transforms the high frequency voltage output by the inverter circuit 3, it is smaller and lighter than the transformer that transforms the AC voltage of the commercial frequency input from the distribution equipment.

The rectifier circuit 5 converts the high-frequency power input from the transformer 4 into DC power and outputs it. The rectifier circuit 5 includes a rectifier circuit that rectifies a high-frequency current and a DC reactor that smoothes the rectifier circuit 5. The configuration of the rectifier circuit 5 is not limited. The DC power output from the rectifier circuit 5 is output from the output terminals a and b.

The current sensor 6 detects the output current of the welding power supply device A1 and is arranged in the connection line connecting one output terminal and the output terminal b of the rectifier circuit 5 in the present embodiment. The current sensor 6 inputs an output current detection signal corresponding to the detected current to the inverter control circuit 7. The configuration of the current sensor 6 is not limited as long as it detects the output current. Further, the location of the current sensor 6 is not limited.

The inverter control circuit 7 is a circuit for controlling the inverter circuit 3, and is realized by, for example, a microcomputer or the like. The inverter control circuit 7 calculates the output current of the welding power supply device A1 based on the output current detection signal input from the current sensor 6. Then, the inverter control circuit 7 generates an output control drive signal for controlling the switching element of the inverter circuit 3 based on the output current and the set current command value, and outputs the output control drive signal to the inverter circuit 3. That is, the inverter control circuit 7 performs feedback control so that the output current of the welding power supply device A1 matches the current command value.

The power factor improvement control circuit 8 is a circuit for controlling the power factor improvement circuit 2. The force factor improvement control circuit 8 transmits the input voltage detection signal Vi detected by the input voltage detection unit 26, the output voltage detection signal Vo detected by the output voltage detection unit 27, and the current detection signal I detected by the current detection unit 28. It is input, generates a power factor improvement drive signal P, and outputs it to the power factor improvement circuit 2. Further, in the power factor improvement control circuit 8, the AC power input to the welding power supply device A1 is single-phase AC power or three-phase based on the voltage between the input terminal v and the input terminal w of the welding power supply device A1. Determine if it is AC power. Then, based on the determination result and the output voltage detection signal Vo detected by the output voltage detection unit 27, the power factor improvement drive signal P is switched between a state of being output and a state of not being output.

The power factor improvement control circuit 8 always outputs the power factor improvement drive signal P to the power factor improvement circuit 2 when the AC power input to the welding power supply device A1 is a single-phase AC power. Therefore, the power factor improving circuit 2 switches the switching element 21 in response to the power factor improving drive signal P to improve the power factor of the DC power input from the rectifier circuit 1.

On the other hand, when the AC power input to the welding power supply device A1 is the three-phase AC power, the power factor improvement control circuit 8 outputs a power factor improvement drive signal P according to the output voltage detection signal Vo and outputs the power factor improvement drive signal P. Switch between not and not. _{Specifically, in the power factor improvement control circuit 8, the output voltage (input voltage of the inverter circuit 3) VDC} of the power factor improvement circuit 2 becomes the second after the input of the three-phase AC power to the welding power supply device A1 is started. The power factor improvement drive signal P is output until the voltage becomes 1 or more. On the other hand, when the output voltage _VDC becomes equal to or higher than the first voltage, the output of the power factor improvement drive signal P is stopped. The first voltage is set to a voltage (for example, about 250 to 270 V) smaller than the set voltage (for example, 280 V) of the output voltage V _DC. The first voltage is not limited. When the switching element 21 of the power factor improving circuit 2 does not switch, the power factor improving circuit 2 becomes a capacitor input type rectifier circuit. Therefore, when the input of the three-phase AC power is started to the welding power supply device A1, the DC voltage input from the rectifier circuit 1 is output as it is, the output voltage _VDC of the power factor improving circuit 2 rises sharply, and the inverter. A rush current flows through the circuit 3. In order to prevent this, in the present embodiment _{, the switching element 21 is made to switch until the output voltage VDC} becomes equal to or higher than the first threshold value, and the output voltage _VDC is slowly increased to prevent a sudden increase. ..

Further, in the present embodiment, the power factor improvement control circuit 8 is an inverter circuit 3 when the input voltage to the welding power supply device A1 drops while the three-phase AC power is input to the welding power supply device A1. It has a function to suppress the decrease of the input voltage of the inverter. Specifically, the power factor improvement control circuit 8, after the output voltage V _DC is equal to or greater than the first voltage, to when it becomes less than the second voltage, the output voltage V _DC is equal to or higher than the first voltage, the force The rate improvement drive signal P is output to the power factor improvement circuit 2. The power factor improvement circuit 2 switches the switching element 21 in response to the power factor improvement drive signal P to boost the DC voltage input from the rectifier circuit 1 and output the DC voltage to increase the output voltage _VDC . The second voltage is set to a voltage smaller than the first voltage (for example, about 220 to 250 V). The second voltage is not limited. As shown in FIG. 1, the power factor improvement control circuit 8 includes a discrimination circuit 81, a comparison circuit 82, an OR circuit 83, a PFC control IC 84, an AND circuit 85, and a drive circuit 86.

The discrimination circuit 81 determines whether the AC power input to the welding power supply device A1 is a three-phase AC power or a single-phase AC power. The determination circuit 81 is connected to the input terminal v and the input terminal w, and determines whether or not a voltage is applied between the input terminal v and the input terminal w. When the voltage is applied, the discrimination circuit 81 determines that the three-phase AC power is input and outputs a low level signal (for example, 0V). On the other hand, when no voltage is applied, it is determined that single-phase AC power is input, and a high-level signal (for example, 15V) is output. Inside the discrimination circuit 81, the circuit connected to the input terminal v and the input terminal w and the circuit that outputs the signal of the discrimination result are insulated by, for example, a photocoupler. The internal configuration of the discrimination circuit 81 is not limited.

The comparison circuit 82 compares the output voltage detection signal Vo input from the output voltage detection unit 27 with the threshold value, and outputs the comparison result. Hysteresis is provided in the comparison circuit 82. The comparison circuit 82 outputs a low level signal when the output voltage detection signal Vo rises and becomes equal to or higher than the threshold value Vref1 corresponding to the first voltage. On the other hand, the comparison circuit 82 outputs a high level signal when the output voltage detection signal Vo drops to the threshold value Vref2 or less corresponding to the second voltage.

FIG. 2A is a circuit diagram showing an example of the internal configuration of the comparison circuit 82. The comparison circuit 82 includes a comparator and resistors R1 to R4. The resistor R1 and the resistor R2 form a voltage dividing circuit connected in series between the power supply voltage Vcc and the ground terminal. The connection point between the resistor R1 and the resistor R2 is connected to the non-inverting input terminal of the comparator. The resistor R3 is connected between the power supply voltage Vcc and the output terminal of the comparator. The resistor R4 is connected between the output terminal of the comparator and the non-inverting input terminal. The inverting input terminal of the comparator is connected to the output voltage detection unit 27, and the output voltage detection signal Vo is obtained _{by dividing the output voltage V DC} of the power factor improving circuit 2 by a voltage dividing circuit using two resistors of the output voltage detecting unit 27. Is entered. A voltage Vref that differs depending on the output voltage Vout of the output terminal of the comparator is input to the non-inverting input terminal of the comparator. The voltage Vref becomes the threshold value Vref1 when the output voltage Vout is a high level voltage (power supply voltage Vcc), and becomes the threshold value Vref2 when the output voltage Vout is a low level voltage (ground voltage). The threshold values Vref1 and Vref2 are set by adjusting the resistance values of the two resistors R1 to R4 and the output voltage detection unit 27 according to the first voltage and the second voltage. When the output voltage detection signal Vo input to the inverting input terminal is larger than the voltage Vref input to the non-inverting input terminal, the comparator outputs a low level signal from the output terminal, and the output voltage detection signal Vo is from the voltage Vref. When it is small, a high level signal is output from the output terminal. The specific circuit configuration of the comparison circuit 82 is not limited.

The OR circuit 83 outputs a logical sum signal of the signal input from the discrimination circuit 81 and the signal input from the comparison circuit 82. Therefore, the OR circuit 83 outputs the high level signal when the high level signal is input from the discrimination circuit 81, that is, when the single-phase AC power is input to the welding power supply device A1. On the other hand, the OR circuit 83 outputs the signal input from the comparison circuit 82 when the low level signal is input from the discrimination circuit 81, that is, when the three-phase AC power is input to the welding power supply device A1. ..

The PFC control IC 84 is an IC that generates a control signal for the power factor improving circuit 2, and in the present embodiment, it generates a control signal for improving the power factor in the current continuous mode. The PFC control IC 84 is input with the input voltage detection signal Vi detected by the input voltage detection unit 26, the output voltage detection signal Vo detected by the output voltage detection unit 27, and the current detection signal I detected by the current detection unit 28. ..

FIG. 2B is a block diagram showing an example of the internal configuration of the PFC control IC 84. The PFC control IC 84 includes an amplifier 841, a multiplier 842, an amplifier 843, an oscillator 844, and a PWM comparator 845. The amplifier 841 outputs a voltage difference signal obtained by amplifying the difference between the output voltage detection signal Vo and the reference voltage to the multiplier 842. The reference voltage is set to a voltage corresponding to the set voltage (for example, 280 _{V) of the output voltage V DC.} The multiplier 842 multiplies the input voltage detection signal Vi as the reference voltage of the sine wave by the voltage difference signal and outputs it to the amplifier 843 as the current reference signal. The amplifier 843 outputs a current difference signal obtained by amplifying the difference between the current reference signal and the current detection signal I to the PWM comparator 845. The oscillator 844 outputs a sawtooth signal of a predetermined frequency to the PWM comparator 845. The PWM comparator 845 generates and outputs a control signal (PWM signal) for the power factor improving circuit 2 based on the current difference signal and the sawtooth wave signal. The specific circuit configuration of the PFC control IC 84 is not limited. Further, the PFC control IC 84 may generate a control signal for improving the power factor in the current discontinuous mode or the current critical mode.

The AND circuit 85 outputs a AND signal of the signal input from the OR circuit 83 and the PWM signal input from the PFC control IC 84. Therefore, when the high level signal is input from the OR circuit 83, the AND circuit 85 outputs the PWM signal input from the PFC control IC 84. On the other hand, when the low level signal is input from the OR circuit 83, the AND circuit 85 outputs the low level signal and does not output the PWM signal input from the PFC control IC 84. That is, the AND circuit 85 switches between a state in which the PWM signal input from the PFC control IC 84 is output and a state in which the PWM signal is not output, according to the signal input from the OR circuit 83.

The drive circuit 86 amplifies the signal input from the AND circuit 85 into a signal at a level capable of driving the switching element 21, and outputs the signal to the switching element 21. When the output signal of the OR circuit 83 is a high level signal, the drive circuit 86 amplifies the PWM signal output by the PFC control IC 84 and inputs it to the switching element 21 as a power factor improvement drive signal P. The switching element 21 switches according to the power factor improvement drive signal P. On the other hand, when the output signal of the OR circuit 83 is a low level signal, the drive circuit 86 receives a low level signal from the AND circuit 85 regardless of the PWM signal output by the PFC control IC 84, and switches the low level signal to the switching element 21. Enter in. That is, in this case, the drive circuit 86 does not output the power factor improvement drive signal P. In the present embodiment, the combination of the PFC control IC 84 and the drive circuit 86 corresponds to the "drive signal generator" of the present invention, and the power factor improvement drive signal P corresponds to the "drive signal" of the present invention.

FIG. 3 is a time chart for explaining the change of each voltage and the change of the power factor improvement drive signal P when the three-phase AC power is input to the welding power supply device A1. FIG. (A) shows the time change _{of the output voltage VDC} of the power factor improving circuit 2. FIG. (B) shows the time change of the output voltage Vout of the comparison circuit 82. FIG. (C) shows the time change of the voltage Vref of the non-inverting input terminal of the comparator of the comparison circuit 82. FIG. (D) shows the time change of the output voltage detection signal Vo detected by the output voltage detection unit 27. FIG. (E) shows the time change of the power factor improvement drive signal P output by the power factor improvement circuit 2. The vertical and horizontal axes of the time chart referred to in the present specification are appropriately enlarged or reduced for easy understanding, and each waveform shown is also simplified for easy understanding. , Or exaggerated or emphasized.

At time t1, the input of the three-phase AC power to the welding power supply device A1 is started. At this time, the output voltage _VDC is "0", and the output voltage detection signal Vo is also "0". Therefore, the output voltage Vout is the high level voltage (Vcc), and the voltage Vref is the threshold value Vref1. Since the output voltage Vout is at a high level, the OR circuit 83 outputs a high level signal, the AND circuit 85 outputs a PWM signal input from the PFC control IC 84, and the power factor improvement control circuit 8 outputs a power factor improvement drive signal P. Is output. Therefore, the output voltage _VDC begins to rise slowly. Until time t2, the output voltage _VDC is less than the first voltage (the output voltage detection signal Vo is less than the threshold voltage Vref1), so the output voltage Vout continues the high level voltage, and the power factor improvement control circuit 8 is the power factor improvement drive signal. The output of P is continued. Therefore, the output voltage _VDC rises slowly. If the power factor improvement control circuit 8 does not output the power factor improvement drive signal P, the output voltage _VDC rises sharply as shown by the alternate long and short dash line in FIG. 3A.

At time t2, the output voltage _VDC is equal to or higher than the first voltage (the output voltage detection signal Vo is equal to or higher than the threshold value Vref1). As a result, the output voltage Vout becomes a low level voltage (ground voltage “0”), and the voltage Vref becomes the threshold value Vref2. Since the output voltage Vout is low level, the OR circuit 83 outputs a low level signal, the AND circuit 85 stops the output of the PWM signal, and the power factor improvement control circuit 8 stops the output of the power factor improvement drive signal P. .. Therefore, the output voltage _VDC is rising sharply. Until time t3, since the output voltage _VDC is the second voltage or higher (the output voltage detection signal Vo is the threshold voltage Vref2 or higher), the output voltage Vout continues the low level voltage, and the power factor improvement control circuit 8 is the power factor improvement drive signal. Continue to stop the output of P.

The output voltage _VDC gradually decreases and becomes the second voltage or less at time t3 (the output voltage detection signal Vo is equal to or less than the threshold value Vref2). As a result, the output voltage Vout becomes a high level voltage, and the voltage Vref becomes the threshold value Vref1. Since the output voltage Vout is at a high level, the power factor improvement control circuit 8 outputs the power factor improvement drive signal P. Therefore, the output voltage _VDC begins to rise slowly. Until time t4, the output voltage _VDC is less than the first voltage (the output voltage detection signal Vo is less than the threshold voltage Vref1), so the output voltage Vout continues the high level voltage, and the power factor improvement control circuit 8 is the power factor improvement drive signal. The output of P is continued. Therefore, the output voltage _VDC rises slowly.

At time t4, since the output voltage _VDC became equal to or higher than the first voltage (because the output voltage detection signal Vo became equal to or higher than the threshold value Vref1), the output voltage Vout became a low level voltage and the voltage Vref became the threshold value Vref2. It has become. Since the output voltage Vout has become low level, the power factor improvement control circuit 8 has stopped the output of the power factor improvement drive signal P.

As described above, the power factor improvement control circuit 8 outputs the power factor improvement drive signal P at the beginning of the input of the three-phase AC power _{to prevent the output voltage VDC} from rising sharply. Further, the power factor improvement control circuit 8 outputs the power factor improvement drive signal P even when _{the output voltage V DC drops, raises the output voltage V DC} , and suppresses the drop in the input voltage of the inverter circuit 3. do.

Next, the operation and effect of the welding power supply device A1 according to the present embodiment will be described.

According to the present embodiment, the power factor improvement control circuit 8 amplifies the power factor improvement drive signal P generated by the PFC control IC 84 when it is determined by the discrimination circuit 81 that the single-phase AC power is input. Is output to the power factor improvement circuit 2. The power factor improvement circuit 2 improves the power factor of the DC power input from the rectifier circuit 1 by switching the switching element 21 according to the power factor improvement drive signal P input from the power factor improvement control circuit 8. And output to the inverter circuit 3. Therefore, the welding power supply device A1 can improve the power factor during single-phase operation. Further, in the power factor improvement control circuit 8, when it is determined by the discrimination circuit 81 that the three-phase AC power has been input, the output voltage _VDC of the power factor improvement circuit 2 becomes the first from the start of the input of the three-phase AC power. The power factor improvement drive signal P is output until the voltage exceeds the voltage to operate the power factor improvement circuit 2, and when the output voltage _VDC exceeds the first voltage, the output of the power factor improvement drive signal P is stopped to operate the power factor. The improvement circuit 2 is stopped. While the power factor improving circuit 2 is operating, the output voltage _VDC slowly rises. _{As a result, the welding power supply device A1 can prevent a sudden rise in the output voltage VDC at} the start of input of the three-phase AC power during the three-phase operation, and can suppress an unnecessary power factor improving operation.

According to the present embodiment, the power factor improvement control circuit 8, when three-phase operation, after the output voltage V _DC is equal to or greater than the first voltage, when it becomes less than the second voltage, the output voltage V _DC is the The power factor improvement drive signal P is output to the power factor improvement circuit 2 until the voltage becomes 1 or more. The power factor improvement circuit 2 switches the switching element 21 in response to the power factor improvement drive signal P to boost the DC voltage input from the rectifier circuit 1 and output the DC voltage to increase the output voltage _VDC . As a result, the welding power supply device A1 can suppress the decrease in the input voltage of the inverter circuit 3 when _{the output voltage VDC decreases during the three-phase operation.}

Further, according to the present embodiment, the OR circuit 83 outputs a logical sum signal of the signal input from the discrimination circuit 81 and the signal input from the comparison circuit 82. Further, the AND circuit 85 outputs a AND signal of the signal input from the OR circuit 83 and the PWM signal input from the PFC control IC 84 to the drive circuit 86. As a result, the power factor improvement control circuit 8 can appropriately switch between the output and the stop of the power factor improvement drive signal P according _{to the output voltage VDC during the three-phase operation.}

Further, according to the present embodiment, the PFC control IC 84 generates a PWM signal for driving the power factor improving circuit 2 in the current continuous mode. As a result, the output current of the power factor improving circuit 2 flows continuously, and the ripple of the output current is small, so that the peak current can be reduced.

In the present embodiment, the power factor improvement control circuit 8, after the output voltage V _DC is equal to or greater than the first voltage, when it becomes less than the second voltage, the output voltage V _DC is equal to or higher than the first voltage Up to this point, the case of outputting the power factor improvement drive signal P has been described, but the present invention is not limited to this. In the power factor improvement control circuit 8, when the output voltage V _DC becomes the first voltage or more and then becomes the second voltage or less, the _{power factor improvement control circuit 8 waits until the output voltage V DC} becomes the third voltage or more different from the first voltage. The power factor improvement drive signal P may be output. The third voltage may be larger or smaller than the first voltage. The first embodiment is the case where the third voltage is equal to the first voltage. Further, the power factor improvement control circuit 8 does _{not have to output the power factor improvement drive signal P even when the output voltage VDC} becomes equal to or higher than the first voltage and then becomes lower than the second voltage. _{That is, the power factor improvement control circuit 8 has a function of preventing a sudden rise in the output voltage VDC} at the start of the three-phase AC power input, but does not have to have a function of suppressing a drop in the input voltage of the inverter circuit 3.

[Second Embodiment]
FIG. 4 is a block diagram showing an internal configuration of the power factor improvement control circuit 8 of the welding power supply device A2 according to the second embodiment. In the figure, the same or similar elements as the welding power supply device A1 (see FIG. 1) according to the first embodiment are designated by the same reference numerals, and redundant description will be omitted. Note that, in FIG. 4, since the configurations other than the power factor improvement control circuit 8 are the same as those of the welding power supply device A1 according to the first embodiment, the description is omitted.

The power factor improvement control circuit 8 of the welding power supply device A2 has a mechanism for stopping the output of the power factor improvement drive signal P, which is different from the power factor improvement control circuit 8 (see FIG. 1) according to the first embodiment.

The power factor improvement control circuit 8 of the welding power supply device A2 does not include the AND circuit 85, but further includes a microcomputer 87. The microcomputer 87 receives a signal from the OR circuit 83. Further, the drive circuit 86 of the welding power supply device A2 outputs a power factor improvement drive signal P that amplifies the PWM signal input from the PFC control IC 84. Further, the drive circuit 86 includes an enable terminal, and when an enable signal is input to the enable terminal, the output of the power factor improvement drive signal P is stopped. When the low level signal is input from the OR circuit 83, the microcomputer 87 inputs the enable signal to the enable terminal of the drive circuit 86. As a result, the power factor improvement control circuit 8 outputs the power factor improvement drive signal P when the OR circuit 83 outputs a high level signal, and outputs a low level signal when the OR circuit 83 outputs a low level signal. Stops the power factor improvement drive signal P.

Also in the present embodiment, the power factor improvement control circuit 8 has a power factor improvement drive signal P based on the discrimination result by the discrimination circuit 81 and the comparison result by the comparison circuit 82, as in the case of the first embodiment. Switch between output and stop. Therefore, the same effect as that of the first embodiment can be obtained.

[Third Embodiment]
FIG. 5 is a block diagram showing an internal configuration of the power factor improvement control circuit 8 of the welding power supply device A3 according to the third embodiment. In the figure, the same or similar elements as the welding power supply device A1 (see FIG. 1) according to the first embodiment are designated by the same reference numerals, and redundant description will be omitted. Note that, in FIG. 5, since the configurations other than the power factor improvement control circuit 8 are the same as those of the welding power supply device A1 according to the first embodiment, the description is omitted.

The power factor improvement control circuit 8 of the welding power supply device A3 has a mechanism for stopping the output of the power factor improvement drive signal P, which is different from the power factor improvement control circuit 8 (see FIG. 1) according to the first embodiment.

The power factor improvement control circuit 8 of the welding power supply device A3 does not include the AND circuit 85, but further includes an insulation switch 88. Further, the drive circuit 86 of the welding power supply device A3 outputs a power factor improvement drive signal P that amplifies the PWM signal input from the PFC control IC 84. The insulation switch 88 is a photocoupler in this embodiment, and when the OR circuit 83 outputs a high level signal, the power supply line of the PFC control IC 84 is conducted and the PFC control IC 84 operates. In this case, the PFC control IC 84 outputs the PWM signal to the drive circuit 86, and the drive circuit 86 outputs the power factor improvement drive signal P. On the other hand, when the OR circuit 83 outputs a low level signal, the insulation switch 88 cuts off the power supply line of the PFC control IC 84, and the PFC control IC 84 stops. In this case, since the PFC control IC 84 does not generate a PWM signal, the drive circuit 86 does not output the power factor improvement drive signal P. As a result, the power factor improvement control circuit 8 outputs the power factor improvement drive signal P when the OR circuit 83 outputs a high level signal, and outputs a low level signal when the OR circuit 83 outputs a low level signal. Stops the power factor improvement drive signal P.

Also in the present embodiment, the power factor improvement control circuit 8 has a power factor improvement drive signal P based on the discrimination result by the discrimination circuit 81 and the comparison result by the comparison circuit 82, as in the case of the first embodiment. Switch between output and stop. Therefore, the same effect as that of the first embodiment can be obtained.

In the first to third embodiments, the case where the present invention is applied to the welding power supply device has been described, but the present invention is not limited to this. For example, the present invention can be applied to a power supply device for arc cutting in which the base material W is cut by an arc generated at the tip, a power supply device for arc gouging in which a groove is carved in the base material W, and the like.

The arc processing power supply device according to the present invention is not limited to the above-described embodiment. The specific configuration of each part of the arc processing power supply device according to the present invention can be freely redesigned.

A1 to A3: Welding power supply, 1: Rectifier circuit, 2: Power factor improvement circuit, 21: Switching element, 3: Inverter circuit, 8: Power factor improvement control circuit, 81: Discrimination circuit, 82: Comparison circuit, 83: OR circuit, 84: PFC control IC, 85: AND circuit, 86: Drive circuit

Claims (5)

A rectifier circuit that inputs three-phase AC power or single-phase AC power and outputs DC power,
A step-up chopper circuit having a switching element, a power factor improving circuit for improving the power factor of DC power input from the rectifier circuit, and a power factor improving circuit.
An inverter circuit that converts DC power input from the power factor improvement circuit into high-frequency power, and
The power factor improvement control circuit that controls the power factor improvement circuit and
With
Outputs the power to generate the arc,
The power factor improvement control circuit
A drive signal generation unit that generates a drive signal for driving the switching element based on the output voltage of the power factor improving circuit.
A discriminant circuit that determines whether three-phase AC power is input or single-phase AC power is input to the rectifier circuit, and
With
When the discrimination circuit determines that the single-phase AC power has been input, the drive signal is input to the switching element, and when it is determined that the three-phase AC power has been input, the three-phase AC power is input. From the start until the output voltage becomes the first voltage or more, the drive signal is input to the switching element, and after the output voltage becomes the first voltage or more, the output of the drive signal is stopped. ,
Arc processing power supply. When the output voltage becomes the second voltage or less after the output voltage becomes the first voltage or more, the power factor improvement control circuit inputs the drive signal to the switching element until it becomes the third voltage or more.
The arc processing power supply device according to claim 1. The power factor improvement control circuit
A comparison circuit that compares the output voltage with the first voltage,
An OR circuit that outputs a logical sum signal of a signal indicating the comparison result of the comparison circuit and a signal indicating the discrimination result of the discrimination circuit, and an OR circuit.
An AND circuit that switches between output and stop of the drive signal according to the OR signal, and
Is further equipped,
The arc processing power supply device according to claim 1 or 2. The drive signal generation unit generates a drive signal for the current continuous mode based on the current flowing through the power factor improving circuit and the input voltage and output voltage of the power factor improving circuit.
The arc processing power supply device according to any one of claims 1 to 3. Welding is performed by the arc generated by the output power.
The arc processing power supply device according to any one of claims 1 to 4.

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