JP2022131146A - power supply - Google Patents

Abstract

To provide a power supply capable of suppressing the occurrence of problems due to the lack of leakage inductance and also capable of suppressing a decrease in maximum output current.SOLUTION: A welding power supply A1 includes: a DC power supply 1; an inverter circuit 2 converting DC voltage input from the DC power supply 1 into high frequency voltage; a transformer 3 transforming the high frequency voltage; a rectification circuit 4 rectifying high frequency voltage transformed by the transformer 3; and a control circuit 5 controlling the inverter circuit 2. The transformer 3 includes a secondary coil 33, a first primary coil 31 arranged to be magnetically coupled with the secondary coil 33, and a second primary coil 32 arranged to be magnetically coupled with the secondary coil 33 with a degree of coupling higher than that of the first primary coil 31. The control circuit 5 excites the first primary coil 31 when the output current of the rectification circuit 4 is less than a predetermined value, and excites the second primary coil 32 when the output current of the rectification circuit 4 is equal to or more than the predetermined value.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply device.

A power supply device is known in which an inverter circuit converts a DC voltage input from a DC power supply into a high-frequency voltage, a transformer transforms the high-frequency voltage, and a rectifier circuit rectifies and outputs the high-frequency voltage. Phase shift control is known as a control method for a single-phase full-bridge inverter circuit. Patent Literature 1 discloses a power supply controlled by phase shift control. In phase shift control, a phase difference is provided in the ON period between the high-side switching element of one arm and the low-side switching element of the other arm of the inverter circuit, and the output is adjusted by the phase difference.

FIG. 6 is a diagram for explaining phase shift control. FIG. 1(a) is a diagram showing the overall configuration of the power supply device A10. FIG. 4(b) is a waveform diagram showing an example of the drive signal input to each switching element. As shown in FIG. 4A, the inverter circuit 20 has a first arm composed of switching elements TR1 and TR3, and a second arm composed of switching elements TR2 and TR4. Drive signals P1 to P4 generated by control circuit 50 are amplified by drive circuit 60 and input to switching elements TR1 to TR4, respectively. As shown in (b) of the figure, the phase of the drive signal P1 lags behind the phase of the drive signal P4. Also, the phase of the driving signal P3 is delayed from the phase of the driving signal P2. The larger the overlapping portion between the pulse of the drive signal P1 (P3) and the pulse of the drive signal P4 (P2), the larger the output. Between the pulse of the drive signal P1 and the pulse of the drive signal P3 (the pulse of the drive signal P2 and the pulse of the drive signal P4), the switching element TR1 and the switching element TR3 (the switching element TR2 and the switching element TR4) are not turned on at the same time. pulse), a dead time is provided.

In a period A shown in FIG. 6B, the switching elements TR1 and TR4 are on, and current flows through the primary winding of the transformer 30 via the switching elements TR1 and TR4. In the period B, the switching element TR4 is turned off, but the energy stored in the leakage inductance of the primary winding of the transformer 30 causes a current to flow through the primary winding via the free wheel diode of the switching element TR2 and the switching element TR1. continue. In period C, the switching element TR2 is turned on. Therefore, in period C, the switching elements TR1 and TR2, which are high-side switching elements, are turned on at the same time. When the switching element TR2 is switched on, current flows through the freewheeling diode, so the drain-source voltage of the switching element TR2 is "0". Therefore, it becomes zero volt switching. In period D, switching element TR1 is turned off, but current continues to flow through the primary winding via the freewheeling diode of switching element TR2, the smoothing capacitor of DC power supply 1, and the freewheeling diode of switching element TR3. During the period E, the switching element TR3 is turned on, and a current in the direction opposite to that during the period A flows through the primary winding via the switching elements TR2 and TR3. When the switching element TR3 is switched on, current flows through the freewheeling diode, so the drain-source voltage of the switching element TR3 is "0". Therefore, it becomes zero volt switching. Thereafter, the high side and low side of the periods B, C, and D are reversed, and the period A returns. Thus, in phase shift control, zero-volt switching can be achieved when each of the switching elements TR1-TR4 is switched on.

Japanese Patent Application Laid-Open No. 2004-322189

However, when the leakage inductance of the primary winding of the transformer 3 is small and the current flowing through the primary winding is small, little energy is stored in the leakage inductance of the primary winding. In this case, the energy is consumed before the period E is reached. If the energy is consumed by the period D, when the switching element TR1 is turned off, the snubber capacitor of the switching element TR1 and the snubber capacitor of the switching element TR3 perform resonance circuit oscillation, and the drain of the switching element TR1 becomes negative. The voltage between the sources oscillates at high frequencies, generating noise. Further, if the energy is consumed by the period E, the snubber capacitor of the switching element TR4 cannot be sufficiently charged. In this case, when the switching element TR3 is switched on, the voltage of the DC power supply 1 may be applied to the switching element TR4 all at once, causing the switching element TR4 to malfunction. Also, if the energy is consumed by the period E, no current flows through the free wheel diode when the switching element TR3 is switched on, and zero-volt switching cannot be achieved. If a coil is connected in series with the primary winding of the transformer 3 to increase the leakage inductance, the above problem can be solved. However, when the leakage inductance increases, the energy transmitted to the secondary side decreases and the current flowing in the secondary side decreases, so the maximum output current of the power supply A10 decreases.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a power supply device capable of suppressing problems caused by insufficient leakage inductance and suppressing a decrease in maximum output current. and

In order to solve the above problems, the present invention takes the following technical means.

A power supply device provided by a first aspect of the present invention includes a DC power supply, an inverter circuit that converts a DC voltage input from the DC power supply into a high frequency voltage, a transformer that transforms the high frequency voltage, and the transformer. A rectifier circuit that rectifies a transformed high-frequency voltage; and a control circuit that controls the inverter circuit. The transformer includes a secondary winding and a first transformer arranged to be magnetically coupled to the secondary winding. and a second primary winding arranged to be magnetically coupled to the secondary winding with a degree of coupling greater than that of the first primary winding, the control circuit comprising: The first primary winding is excited when the output current of the rectifier circuit is less than a predetermined value, and the second primary winding is excited when the output current of the rectifier circuit is greater than or equal to the predetermined value.

A power supply device provided by a second aspect of the present invention includes a DC power supply, an inverter circuit that converts a DC voltage input from the DC power supply into a high frequency voltage, a transformer that transforms the high frequency voltage, and the transformer. A rectifier circuit that rectifies a transformed high-frequency voltage; and a control circuit that controls the inverter circuit. The transformer includes a secondary winding and a first transformer arranged to be magnetically coupled to the secondary winding. a primary winding and a second primary winding, and the control circuit excites only the first primary winding when the output current of the rectifier circuit is less than a predetermined value, thereby energizing the rectifier circuit. When the output current of is greater than or equal to a predetermined value, both the first primary winding and the second primary winding are excited.

In a preferred embodiment of the present invention, the first primary winding is wound over the secondary winding, and the leakage inductance is adjusted by the size of the gap from the secondary winding. be done.

In a preferred embodiment of the present invention, the first primary winding is wound over the secondary winding, and the area of overlap with the secondary winding adjusts the leakage inductance. .

In a preferred embodiment of the present invention, the first primary winding is overwound on the secondary winding, the leakage inductance is is adjusted.

In a preferred embodiment of the present invention, the inverter circuit includes two high-side switching elements connected to the positive side of the DC power supply and two low-side switching elements connected to the negative side of the DC power supply. and the control circuit turns on the two high-side switching elements at the same time, or turns on the two low-side switching elements at the same time.

In a preferred embodiment of the present invention, the inverter circuit includes a first arm, a second arm, and a third arm having two switching elements connected in series, and the control circuit comprises and driving the switching elements of the second arm to excite the first primary winding, and driving the switching elements of the first arm and the third arm to drive the switching elements of the second primary Energize the windings.

According to the invention, a transformer comprises a first primary winding and a second primary winding magnetically coupled to a secondary winding. The control circuit energizes the first primary winding, which has a relatively low degree of coupling, when the output current is small. In this case, since the leakage inductance can be made larger than when the second primary winding is excited, the occurrence of problems due to insufficient leakage inductance can be suppressed. On the other hand, the control circuit excites the second primary winding, which has a relatively high degree of coupling, when the output current is large. In this case, since the leakage inductance can be made smaller than when the first primary winding is excited, it is possible to suppress a decrease in the current flowing through the secondary side. Therefore, it is possible to suppress a decrease in the maximum output current of the power supply device.

Other features and advantages of the present invention will become more apparent from the detailed description given below with reference to the accompanying drawings.

1 is a diagram showing the overall configuration of a welding power supply according to a first embodiment; FIG. 1 is a simplified external view for explaining a transformer; FIG. FIG. 10 is a cross-sectional view showing a modification of the transformer; FIG. 5 is a simplified external view for explaining a modified example of the transformer; FIG. 10 is a diagram showing the overall configuration of a welding power supply according to a second embodiment; 1(a) is an external view showing the overall configuration of a conventional welding power supply, and FIG. 1(b) is a waveform diagram showing an example of a drive signal input to each switching element.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings, taking as an example a case where a power source device according to the present invention is used as a welding power source device.

[First Embodiment]
FIG. 1 is a diagram for explaining the welding power supply A1 according to the first embodiment, and shows the overall configuration of the welding power supply A1.

The welding power supply A1 generates an arc between the tip of the electrode of the welding torch T and the workpiece W, and supplies power to the arc. As shown in FIG. 1, the welding power supply A1 includes a DC power supply 1, an inverter circuit 2, a transformer 3, a rectifier circuit 4, a control circuit 5, a drive circuit 6, and a current sensor 7.

A DC power supply 1 outputs a DC voltage, and includes, for example, a rectifier circuit that rectifies an AC voltage that is input from a power system, and a smoothing capacitor that smoothes the voltage. Note that the configuration of the DC power supply 1 is not limited as long as it outputs a DC voltage to the inverter circuit 2 .

The inverter circuit 2 converts the DC voltage input from the DC power supply 1 into a high frequency voltage and outputs the high frequency voltage to the transformer 3 . The inverter circuit 2 is a single-phase full-bridge inverter, and includes six switching elements TR1 to TR6. In this embodiment, MOSFETs (Metal Oxide Semiconductor Field Effect Transistors) are used as the switching elements TR1 to TR6. The switching elements TR1 to TR6 are not limited to MOSFETs, and may be bipolar transistors, IGBTs (Insulated Gate Bipolar Transistors), or the like.

The switching element TR1 and the switching element TR3 are connected in series by connecting the source terminal of the switching element TR1 and the drain terminal of the switching element TR3. The drain terminal of the switching element TR1 is connected to the positive electrode side of the DC power supply 1, and the source terminal of the switching element TR3 is connected to the negative electrode side of the DC power supply 1, forming a bridge structure. Similarly, the switching element TR2 and the switching element TR4 are connected in series to form a bridge structure, and the switching element TR5 and the switching element TR6 are connected in series to form a bridge structure. A first arm is a bridge structure formed by the switching elements TR1 and TR3, a second arm is a bridge structure formed by the switching elements TR2 and TR4, and a switching element TR5 and a switching element TR6. Let the bridge structure formed by be a 3rd arm. An output line C1 is connected to a connection point between the switching elements TR1 and TR3 of the first arm, an output line C2 is connected to a connection point of the switching elements TR2 and TR4 of the second arm, and an output line C2 is connected to the connection point of the switching elements TR2 and TR4 of the second arm. An output line C3 is connected to the connection point between the switching element TR5 and the switching element TR6. The switching elements TR1, TR2 and TR5 correspond to the "high side switching element" of the invention, and the switching elements TR3, TR4 and TR6 correspond to the "low side switching element" of the invention. In this embodiment, the switching elements TR5 and TR6 use elements having a smaller rated current than the switching elements TR1 and TR3. Also, the switching elements TR2 and TR4 use elements having a smaller rated current than the switching elements TR5 and TR6.

Free wheel diodes are connected in anti-parallel to the switching elements TR1 to TR6. A snubber capacitor is connected between the drain terminal and the source terminal of each of the switching elements TR1 to TR6. Drive signals P1 to P6 (described later) output from the drive circuit 6 are input to the gate terminals of the switching elements TR1 to TR6, respectively. The switching elements TR1-TR6 are switched between on and off based on drive signals P1-P6, respectively. This converts the direct current into an alternating current. Note that the configuration of the inverter circuit 2 is not limited.

The transformer 3 transforms the high-frequency voltage output by the inverter circuit 2 and outputs the transformed high-frequency voltage to the rectifier circuit 4 . FIG. 2 is a simplified external view for explaining the transformer 3. FIG. The transformer 3 comprises a first primary winding 31, a second primary winding 32, a secondary winding 33 and a core 34. The core 34 is a magnetic member such as ferrite for improving the magnetic coupling between the first primary winding 31 and the second primary winding 32 and the secondary winding 33. In this embodiment, As shown in FIG. 2, it has a substantially rectangular ring shape.

As shown in FIG. 1, one input terminal of the first primary winding 31 is connected to the output line C1 and the other input terminal is connected to the output line C2. One input terminal of the second primary winding 32 is connected to the output line C1, and the other input terminal is connected to the output line C3. One output terminal of secondary winding 33 is connected to one input terminal of rectifier circuit 4 , and the other output terminal is connected to the other input terminal of rectifier circuit 4 . The secondary winding 33 is provided with a center tap in addition to the two output terminals. A first primary winding 31, a second primary winding 32, and a secondary winding 33 are each wound around a core 34 and can be magnetically coupled with each other.

In this embodiment, as shown in FIG. 2, a second primary winding 32 and a secondary winding 33 are wound around a core 34 in an overlapping manner. Therefore, the degree of coupling between the second primary winding 32 and the secondary winding 33 is high and the leakage inductance is small. The method of winding the second primary winding 32 and the secondary winding 33 is not limited as long as the degree of coupling is high and the leakage inductance is small. For example, the method of winding the second primary winding 32 and the secondary winding 33 may be bifilar winding. On the other hand, the first primary winding 31 is wound away from the secondary winding 33 . Therefore, the first primary winding 31 has a lower degree of coupling with the secondary winding 33 and a larger leakage inductance than the second primary winding 32 . The method of winding the first primary winding 31 and the secondary winding 33 is not limited as long as the degree of coupling is relatively low and the desired leakage inductance is obtained. Also, the configuration of the transformer 3 is not limited to this.

FIG. 3 is a cross-sectional view showing a modification of the transformer 3. As shown in FIG. In this modified example, a second primary winding 32 is wound around a core 34, and a secondary winding 33 is wound in an overlapping manner on the outside thereof. A first primary winding 31 is wound around the secondary winding 33 . In FIG. 3A, the distance between the secondary winding 33 and the first primary winding 31 is increased by increasing the thickness of the insulating member (not shown) between the secondary winding 33 and the first primary winding 31. increasing L. As a result, the degree of coupling between the first primary winding 31 and the secondary winding 33 is lower than that of the second primary winding 32, and the leakage inductance is increased. In this modified example, the degree of coupling between the first primary winding 31 and the secondary winding 33 can be adjusted according to the size of the interval L, thereby adjusting the leakage inductance. In FIG. 3B, by winding the secondary winding 33 and the first primary winding 31 with a shift, the overlapping area S between the secondary winding 33 and the first primary winding 31 is reduced. is doing. As a result, the degree of coupling between the first primary winding 31 and the secondary winding 33 is lower than that of the second primary winding 32, and the leakage inductance is increased. In this modified example, the degree of coupling between the first primary winding 31 and the secondary winding 33 can be adjusted by the overlapping area S, thereby adjusting the leakage inductance. Of course, the degree of coupling between the first primary winding 31 and the secondary winding 33 may be adjusted by adjusting both the spacing L and the overlapping area S described above.

The rectifier circuit 4 is a full-wave rectifier circuit using the center tap of the transformer 3, rectifies the high-frequency current output from the transformer 3, and outputs it as a direct current. The rectifier circuit 4 includes two rectifier diodes 41 and 42 and a DC reactor 43 . The rectifying diodes 41 and 42 have their anode terminals connected to the output terminals of the secondary winding 33 of the transformer 3, and their cathode terminals connected to each other. The DC reactor 43 is connected in series between the connection point on the cathode terminal side of the rectifying diodes 41 and 42 and the output terminal a of the welding power source A1, and stabilizes the output current. A center tap of the transformer 3 is connected to an output terminal b of the welding power supply A1. A DC current output from the rectifier circuit 4 flows through the welding torch T as a welding current. Note that the configuration of the rectifier circuit 4 is not limited.

The current sensor 7 is arranged on the connection line between the center tap of the transformer 3 and the output terminal b, detects the output current of the welding power source A1, and outputs it to the control circuit 5 as a current signal. The arrangement position of the current sensor 7 is not limited as long as the output current of the rectifier circuit 4 can be detected.

The control circuit 5 controls the inverter circuit 2 , generates a drive signal for controlling the inverter circuit 2 , and outputs the drive signal to the drive circuit 6 . The control circuit 5 performs output current control, and feedback-controls the output current of the welding power source A1 based on the current signal input from the current sensor 7 . The control circuit 5 also performs phase shift control. The control circuit 5 includes a target setting section 51 and a drive signal generation section 52 .

Target setting unit 51 sets a target current value, which is the target value of the output current of welding power supply A1. The target setting unit 51 outputs the set target current value to the drive signal generation unit 52 . The target setting unit 51 sets the target current value based on the welding conditions input by the operator or programmed in advance.

The driving signal generator 52 generates pulse signals having a predetermined duty ratio and a predetermined frequency, and outputs the generated pulse signals to the drive circuit 6 as the driving signals P1 to P6. At this time, the drive signal generation unit 52 generates the drive signal P1 and the drive signal P4 (or the drive signal P6) and output with a phase difference, and output with a phase difference between the driving signal P3 and the driving signal P2 (or the driving signal P5). The waveforms of the drive signals P1 to P4 are similar to the waveforms shown in the waveform diagram of FIG. 6(b). The waveform of the driving signal P5 is similar to that of the driving signal P2, and the waveform of the driving signal P6 is similar to that of the driving signal P4. The drive signals P1-P6 are amplified by the drive circuit 6 and input to the gate terminals of the switching elements TR1-TR6, respectively. By providing a phase difference, the portion where the pulse of the drive signal P1 and the pulse of the drive signal P4 (P6) overlap and the portion where the pulse of the drive signal P3 and the pulse of the drive signal P2 (P5) overlap become small. Therefore, even if the pulse width is the same, the output can be made smaller than when no phase difference is provided. The drive signal generator 52 reduces the output by increasing the phase difference as the deviation between the current signal and the target current value increases. On the other hand, the drive signal generator 52 increases the output by decreasing the phase difference as the deviation is smaller. The method of generating the drive signals P1 to P6 by the drive signal generator 52 is not limited.

Further, the drive signal generation unit 52 changes the drive signal to be output based on the target current value input from the target setting unit 51 . The drive signal generator 52 compares the target current value with a preset threshold value. When the target current value is less than the threshold value, drive signal generator 52 determines that the output current of welding power supply A1 (rectifier circuit 4) is small (small output state). In the small output state, the drive signal generator 52 outputs the drive signals P1 to P4 and does not output the drive signals P5 to P6. On the other hand, when the target current value is equal to or greater than the threshold value, drive signal generator 52 determines that the output current of welding power supply A1 (rectifier circuit 4) is large (high output state). In the high output state, the drive signal generator 52 outputs the drive signals P1, P3, P5 and P6 and does not output the drive signals P2 and P4. That is, the drive signal generator 52 always outputs the drive signals P1 and P3, outputs the drive signals P2 and P4 in the low output state, and outputs the drive signals P5 and P6 in the high output state. do. As for the threshold value, a current value for separating a low output state and a high output state is set based on experiments and simulations. Specifically, the threshold value is set so that the high output state is a state in which problems due to insufficient leakage inductance can be suppressed even when a current is passed through the second primary winding 32. For example, the welding power source A value of about 50 to 60% of the rated current of the device A1 is set. Note that the threshold is not limited.

Note that the drive signal generator 52 may determine the low output state and the high output state based on the current signal input from the current sensor 7 . Further, drive signal generator 52 may determine the low output state and the high output state based on the output power of welding power supply A1 (rectifier circuit 4). Further, in the high output state, the drive signal generator 52 (drive circuit 6) outputs the drive signal P2 to the switching element TR5 instead of the switching element TR2, and outputs the drive signal P4 to the switching element TR4 instead of the switching element TR4. It may be output to element TR6.

In the small output state, the drive signal generator 52 outputs the drive signals P1 to P4 to drive the switching elements TR1 to TR4. As a result, the inverter circuit 2 supplies a high-frequency current to the first primary winding 31 to excite it. On the other hand, in the high output state, the drive signal generator 52 outputs P1, P3, P5 and P6 to drive the switching elements TR1, TR3, TR5 and TR6. As a result, the inverter circuit 2 supplies a high-frequency current to the second primary winding 32 to excite it.

Next, the effects of welding power supply A1 will be described.

According to this embodiment, the transformer 3 comprises a first primary winding 31 and a second primary winding 32 magnetically coupled to a secondary winding 33 . The first primary winding 31 has a lower degree of coupling with the secondary winding 33 and a larger leakage inductance than the second primary winding 32 . In the small output state, the control circuit 5 outputs drive signals P1 to P4 to drive the switching elements TR1 to TR4. As a result, the inverter circuit 2 supplies a high-frequency current to the first primary winding 31 to excite it. In this case, since the leakage inductance can be made larger than when the second primary winding 32 is excited, problems due to insufficient leakage inductance can be suppressed. On the other hand, the control circuit 5 outputs drive signals P1, P3, P5 and P6 in the high output state to drive the switching elements TR1, TR3, TR5 and TR6. As a result, the inverter circuit 2 supplies a high-frequency current to the second primary winding 32 to excite it. In this case, since the leakage inductance can be made smaller than when the first primary winding 31 is excited, it is possible to suppress the decrease in the current flowing to the secondary side. Therefore, a decrease in the maximum output current of welding power supply A1 can be suppressed.

Further, according to this embodiment, the control circuit 5 performs phase shift control. Therefore, the inverter circuit 2 has a period in which the high-side switching element TR1 and the switching element TR2 (or the switching element TR5) are simultaneously turned on (see period C in FIG. 6B), and a period in which the low-side switching element TR3 and It has a period in which the switching element TR4 (or the switching element TR6) is turned on at the same time. Energy stored in the leakage inductance causes current to circulate during these periods, allowing the inverter circuit 2 to achieve zero-volt switching of the switching elements TR1-TR6. In addition, in the low output state, the first primary winding 31 having a large leakage inductance is used, so that a state in which zero-volt switching cannot be performed is suppressed.

In this embodiment, the welding power source A1 excites the first primary winding 31 in the low output state, and excites the second primary winding 32 in the high output state. has been described, but it is not limited to this. Welding power supply A1 may excite both first primary winding 31 and second primary winding 32 in the high output state. Specifically, in the high output state, the drive signal generator 52 outputs all the drive signals P1 to P6 to drive all the switching elements TR1 to TR6. The switching element TR2 and the switching element TR5 perform the same operation, and the switching element TR4 and the switching element TR6 perform the same operation. Therefore, the inverter circuit 2 causes high-frequency current to flow through the first primary winding 31 and the second primary winding 32 to excite both the first primary winding 31 and the second primary winding 32 . As a result, welding power supply A1 can further increase the degree of coupling in the high output state, as compared with the case where only second primary winding 32 is excited. Therefore, the welding power source A1 can further reduce the leakage inductance in the high output state, thereby further suppressing the decrease in the current flowing to the secondary side. In this case, the first primary winding 31 and the second primary winding 32 may have the same degree of coupling with the secondary winding 33 . Thus, as shown in FIG. 4, the first primary winding 31 and the second primary winding 32 may be positioned equally distant from the secondary winding 33 .

[Second embodiment]
FIG. 5 is a diagram for explaining the welding power supply A2 according to the second embodiment, and shows the overall configuration of the welding power supply A2. In the figure, elements identical or similar to those of the welding power source A1 (see FIG. 1) are denoted by the same reference numerals, and overlapping descriptions are omitted. The welding power source A2 according to this embodiment differs from the welding power source A1 in the switching method between the first primary winding 31 and the second primary winding 32 .

In this embodiment, the inverter circuit 2 does not include the switching element TR5 and the switching element TR6 (third arm). Also, in the transformer 3 , the second primary winding 32 is connected in parallel with the first primary winding 31 . That is, one input terminal of the second primary winding 32 is connected to the output line C1, and the other input terminal is connected to the output line C2. A switch 35 is connected in series to the second primary winding 32 . The switch 35 is switched on and off by the control circuit 5 . When the switch 35 is on, the second primary winding 32 is connected in parallel with the first primary winding 31 . On the other hand, when the switch 35 is off, the second primary winding 32 is disconnected from the first primary winding 31 . The switch 35 may be a semiconductor switch or a mechanical switch.

Moreover, in this embodiment, the control circuit 5 further includes a switching section 53 . The drive signal generator 52 of this embodiment outputs the drive signals P1 to P4 regardless of whether it is in the low output state or the high output state. The switching section 53 switches the switch 35 based on the target current value input from the target setting section 51 . The switching unit 53 determines whether the output state is the low output state or the high output state, similarly to the drive signal generation unit 52 of the first embodiment. The switching unit 53 turns off the switch 35 in the low output state. In this case, the high-frequency current output by the inverter circuit 2 flows only through the first primary winding 31 and excites only the first primary winding 31 . On the other hand, the switching unit 53 turns on the switch 35 in the high output state. In this case, the high-frequency current output by the inverter circuit 2 flows through the first primary winding 31 and the second primary winding 32, causing both the first primary winding 31 and the second primary winding 32 to to excite

According to this embodiment, the control circuit 5 turns off the switch 35 and excites only the first primary winding 31 in the low output state. This suppresses the occurrence of problems due to insufficient leakage inductance. On the other hand, in the high output state, the control circuit 5 turns on the switch 35 to excite both the first primary winding 31 and the second primary winding 32 . This reduces the leakage inductance and suppresses the decrease in the current flowing through the secondary side, thereby suppressing the decrease in the maximum output current of the welding power source A2. Also in this embodiment, since the control circuit 5 performs phase shift control, the inverter circuit 2 can realize zero-volt switching.

In this embodiment, the welding power supply A2 excites the first primary winding 31 in the low output state, and excites the first primary winding 31 and the second primary winding 31 in the high output state. Although the case where both primary windings 32 are excited has been described, the present invention is not limited to this. Welding power supply A2 may excite only second primary winding 32 in the high output state. Specifically, the transformer 3 may further include a switch connected in series with the first primary winding 31, and the switching unit 53 may also switch the switch.

In the first and second embodiments described above, the case where the present invention is applied to the welding power source has been described, but the present invention is not limited to this. INDUSTRIAL APPLICABILITY The present invention can be applied to all power supply devices in which an inverter circuit converts a DC voltage into a high-frequency voltage and a transformer transforms the high-frequency voltage.

The power supply device according to the present invention is not limited to the above-described embodiments. The specific configuration of each part of the power supply device according to the present invention can be changed in various ways.

A1, A2: Welding power supply, 1: DC power supply, 2: Inverter circuit, 3: Transformer, 31: First primary winding, 32: Second primary winding, 33: Secondary winding, 4: Rectification circuit, 5: control circuit

Claims (6)

a DC power supply;
an inverter circuit that converts a DC voltage input from the DC power supply into a high-frequency voltage;
a transformer that transforms the high-frequency voltage;
a rectifier circuit that rectifies the high-frequency voltage transformed by the transformer;
a control circuit that controls the inverter circuit;
with
The transformer includes a secondary winding, a first primary winding arranged to be magnetically coupled to the secondary winding, and a higher degree of coupling to the secondary winding than the first primary winding. a second primary winding arranged for magnetic coupling;
The control circuit excites the first primary winding when the output current of the rectifier circuit is less than a predetermined value, and excites the second primary winding when the output current of the rectifier circuit is greater than or equal to a predetermined value. to excite,
Power supply. a DC power supply;
an inverter circuit that converts a DC voltage input from the DC power supply into a high-frequency voltage;
a transformer that transforms the high-frequency voltage;
a rectifier circuit that rectifies the high-frequency voltage transformed by the transformer;
a control circuit that controls the inverter circuit;
with
the transformer comprises a secondary winding, a first primary winding and a second primary winding arranged to be magnetically coupled to the secondary winding;
The control circuit excites only the first primary winding when the output current of the rectifier circuit is less than a predetermined value, and excites the first primary winding when the output current of the rectifier circuit is greater than or equal to the predetermined value. and energizing both the second primary winding;
Power supply. The first primary winding is wound over the secondary winding, and the leakage inductance is adjusted by the size of the distance from the secondary winding.
The power supply device according to claim 1 or 2. The first primary winding is wound so as to overlap the secondary winding, and the leakage inductance is adjusted by the overlapping area with the secondary winding.
The power supply device according to any one of claims 1 to 3. The inverter circuit includes two high-side switching elements connected to the positive electrode side of the DC power supply and two low-side switching elements connected to the negative electrode side of the DC power supply,
The control circuit turns on the two high-side switching elements at the same time, or turns on the two low-side switching elements at the same time.
The power supply device according to any one of claims 1 to 4. The inverter circuit includes a first arm, a second arm, and a third arm having two switching elements connected in series,
The control circuit drives the switching elements of the first arm and the second arm to excite the first primary winding and drive the switching elements of the first arm and the third arm. exciting the second primary winding by causing
The power supply device according to any one of claims 1 to 5.

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