JPH0518763U - Power supply for arc processing - Google Patents

Abstract

(57) [Summary] [Objective] We propose an inverter-type power supply device for arc machining that can be shared by two AC power supplies with a ratio of 1: 2 such as 200V and 400V. A first and a second series circuit composed of two diodes and a third series circuit composed of two capacitors are connected in parallel to each other, and an interconnection point of the diodes of the first series circuit. Is one of the input terminals to the commercial single-phase AC power supply, and either the interconnection point of the diode of the second series circuit or the interconnection point of the capacitor of the third series circuit is selected according to the input voltage. A power supply device for arc machining, comprising: an input voltage changeover switch that is connected to the other input terminal to the commercial single-phase alternating current; and an inverter circuit that receives each terminal voltage of a capacitor of the third series circuit as an input.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention uses commercial alternating current as input, rectifies input power once to convert it to direct current, and then inversely converts it to high frequency alternating current by an inverter circuit, and the high frequency alternating current obtained by this inverse conversion is arced by a transformer or a rectifier circuit. It relates to an arc processing power supply that reconverts the output to a power suitable for processing, and is especially shared by two systems of power supply such as 200V and 400V, 230V and 460V that have a ratio of approximately 1: 2 as a commercial AC power supply. This is a device that can be used.

[0002]

[Prior Art]

 As an arc-processing power source that can be shared by two power sources with an input power source voltage of 200 V and 400 V or 230 V and 460 V and a ratio of approximately 1: 2, a commercial AC power source can be directly transformed into a predetermined voltage by a transformer. In this case, different power supply voltages can be accommodated by switching the turns ratio of the transformer. However, in a system in which a commercial AC power source is rectified into a direct current, it is inversely converted into a high frequency alternating current by an inverter circuit, and the high frequency alternating current obtained by this inverse conversion is converted into a desired voltage by a transformer. Is a method of switching the turns ratio of the transformer, and withstand voltage of 400V (or 460V) in an inverter circuit or rectifier circuit located on the power source side or a line filter for noise removal, and when the voltage is 200V (or 230V). It is necessary to use a switching element or diode with a capacity that can withstand the large currents in the circuit, resulting in a large and expensive circuit. The effect of miniaturizing the was offset.

In addition, when the DC voltage output after rectification is a high voltage, a half-bridge type inverter circuit is configured by two series capacitors and two switching elements, and when the voltage is low, a full bridge is formed by four switching elements. There has also been proposed a system in which a voltage inverter circuit is configured to equalize the voltages applied to the switching elements that configure the inverter circuit and to equalize the output voltage of the inverter circuit.

FIG. 1 is a connection diagram showing an example of a conventional device of the above system. In the figure, 1a, 1b, 2a and 2b are rectifying diodes, which perform full-wave rectification of the single-phase AC power source supplied from the input terminal UV. Capacitors 3a and 3b smooth the rectified output of the diode 1a or 2b and divide the output voltage into two equal parts. Switching elements 4a to 4d are bridge-connected, and the low-voltage side contacts of the switching switch 5 and the primary winding of the output transformer 6 are connected to respective series connection points. The high voltage side contact of the changeover switch 5 is connected to the series connection point of the capacitors 3a and 3b, and the common terminal of the changeover switch 5 is connected to the primary winding of the output transformer 6. Reference numeral 7 denotes a load connected to the secondary winding of the transformer 6, for example, a rectifier circuit and an arc machining load, or a rectifier circuit, a low frequency inverter circuit and an arc machining load. Further, LF is a line filter whose main constituent element is a reactor provided so that noise generated when the switching element is turned on and off does not propagate to the external power supply line. It is provided in the DC portion between the input terminal or the rectifying diodes 1a, 1b, 2a, 2b and the inverter circuit.

In the device shown in the figure, when the single-phase AC power supply is 200 V (or 230 V), the changeover switch 5 is connected to the (a) side, and the switching elements 4a to 4d operate as a bridge-connected inverter. The primary winding of the output transformer 6 is connected between the connection point of the switching elements 4a and 4c and the connection point of the switching elements 4b and 4d. At this time, the switching elements 4a and 4b and the switching elements 4c and 4d form one set, and the sets are simultaneously and alternately turned on and off by a control circuit (not shown). At this time, the capacitors 3a and 3b act as a single smoothing capacitor. On the other hand, when the single-phase AC power source is 400V (or 460V or the like), the changeover switch 5 is connected to the (b) side. In this case, the primary winding of the output transformer 6 is connected between the connection point of the capacitors 3a and 3b and the connection point of the switching elements 4a and 4c to form a half bridge circuit. As a result, 1/2 of the rectified output is applied to the transformer 6, and the same voltage output as that at 200 V (230 V) is obtained. In this case, the switching elements 4a and 4c are alternately turned on and off, and the switching elements 4b and 4d remain off.

[0006]

[Problems to be solved by the device]

 In the above conventional device, the inverter circuit can obtain the same output voltage even if the voltage of the AC input power source changes to 1: 2. Therefore, the withstand voltage of the switching element of the inverter circuit is higher than that of the method of switching the turns ratio of the transformer. May correspond to the lower voltage, but two switching elements play at the time of high voltage input, and the line filter LF and the diodes 1a to 2b forming the rectifying circuit on the input side have an input of 400V. A large capacity that can withstand a voltage and a large input current at 200V is required. Furthermore, since the configuration of the inverter circuit is switched to the full bridge type and the half bridge type by the changeover switch 5, the wiring of the inverter circuit becomes long and complicated, the inductance and stray capacitance of the wiring increase, and the inverter operates at high frequency. At times, the surge voltage generated when the switching element is turned on and off becomes high, which requires a countermeasure and a large capacity of the surge absorption circuit.

[0007]

[Means for Solving the Problems]

 In the present invention, the rectifier circuit that rectifies a single-phase alternating current to obtain a direct current power source is a double voltage rectifier circuit at low voltage input, a double wave rectifier circuit at high voltage input, and a line filter is used as a rectifier circuit and an inverter. When connected to the circuit, the same rectified output as at the time of high voltage input can be obtained in both power supplies with an AC input voltage of approximately 1: 2, which allows the rectifier circuit, the inverter circuit, and the line filter to be connected. This is to obtain a device that has no waste and does not increase surge voltage in the inverter circuit.

[0008]

【Example】

 FIG. 2 shows a connection diagram of an embodiment of the present invention. In the figure, 1a, 1b, 2a and 2b are diodes, 3a and 3b are capacitors, 8a and 8b are switching elements, and each two are connected in series and then connected in parallel as shown in the figure. The capacitors 3a and 3b and the switching elements 8a and 8b constitute a half-bridge type inverter circuit. Further, 9a and 9b are changeover switches, which operate in conjunction with each other. 6 is an output transformer, and 7 is a load of the output transformer 6. As in the conventional device of FIG. 1, a rectifier circuit and electrodes, an arc load composed of an arc and a workpiece, or a rectifier circuit and a low-frequency inverter circuit and arc. It consists of loads. Reference numeral 10 denotes an inverter control circuit that alternately turns ON / OFF the switching elements 8a and 8b at a predetermined conduction ratio, and a known PWM control circuit can be used. LF a and LF b are reactors that form a line filter, both reactors share an iron core, and the polarities of both windings are appropriately adjusted to the polarities that form a common mode filter or a normal mode filter, if necessary. Determined.

In the figure, when the changeover switches 9a and 9b are on the (a) side, that is, on the 200V side, the diodes 1a (and 2a) and 1b (and 2b) and the capacitors 3a and 4a are used for the single-phase AC power supply. A voltage doubler rectifier circuit that receives On the other hand, when the switching switches 9a and 9b are on the (b) side, that is, on the 400V side, the interconnection point between the capacitors 3a and 3b is disconnected from the power source, and the diodes 1a, 1b, 2a, and 2b form a single-phase circuit. A wave rectification circuit is constructed. Here, the capacitors 3a and 3b are capacitors for dividing the rectified output into two equal parts, and the rectified output divided into two parts is alternately turned on by the inverter control circuit 10 via the line filters LFa and LFb. After being converted into a high-frequency AC by a half-bridge type inverter circuit composed of switching elements 8a and 8b which are controlled to be turned off, it is converted into a desired voltage by an output voltage converter 6 and supplied to a load 7.

In the device of the same figure, the rectified output always has the same value as the full-wave rectified output voltage at the time of high voltage input, even if the voltage of the single-phase AC power supply has different values at a ratio of 1: 2. This DC output is divided into two equal parts by a capacitor and inversely converted into high-frequency AC by a half-bridge type inverter circuit. Therefore, neither the rectifier circuit nor the inverter circuit line filter has a capacity waste and the inverter is Since the wiring of the circuit is simple, the generation of surge voltage does not increase.

In the embodiment of FIG. 2, by utilizing the fact that the output voltage is divided into two equal parts by the capacitors 3a and 3b, a half-bridge type inverter is constructed by using these and two switching elements. However, a voltage equal to the voltage obtained by double-wave rectifying 400V is always obtained at both ends of the series circuit of the capacitors 3a and 3b regardless of whether the input power supply voltage is 200V or 400V. A full-bridge type inverter using four switching elements may be used. FIG. 3 is a connection diagram showing an embodiment of the present invention in such a case. In the figure, four switching elements 11a to 11d are connected to a bridge and connected to both ends of the capacitors 3a and 3b via line filters LFa and LFb. In the embodiment shown in the figure, the same operation as that of the embodiment shown in FIG. 2 is performed except that the voltage applied to the transformer 6 becomes high. In the embodiments of FIGS. 2 and 3, the diodes 1a and 2a and the diodes 1b and 2b are arranged in parallel by the changeover switch 9b at the time of low voltage input, but the changeover switch 9b need not be provided in particular. ..

[0012]

[Effect of the device]

 In the present invention, in both voltages in which the voltage of the single-phase AC power supply has a ratio of 1: 2, the rectified DC output is always equal to the double-wave rectified voltage at the time of high voltage input. Is divided into two by a series capacitor to obtain a two-voltage output, and a high-frequency AC is obtained by a half-bridge type inverter circuit using two switching elements or the obtained DC voltage as it is by a full-bridge type inverter circuit. Therefore, it is not necessary to unnecessarily increase the voltage and current ratings of each element of the rectifier circuit, the inverter circuit, and the line filter, and the inverter circuit does not have a switching circuit depending on the input power supply voltage, so the circuit is simple. There is no increase in surge voltage generated during switching.

[Brief description of drawings]

FIG. 1 is a connection diagram showing an example of a conventional device.

FIG. 2 is a connection diagram showing an embodiment of the present invention.

FIG. 3 is a connection diagram showing another embodiment of the present invention.

[Explanation of symbols]

1a, 1b, 2a, 2b diode 3a, 3b capacitor 6 output transformer 7 load 8a, 8b, 11a, 11b, 11c, 11d switching element 9a, 9b changeover switch 10 inverter control circuit LF line filter LFa, LFb reactor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Masashi Horii, 2-11-1, Tagawa, Yodogawa-ku, Osaka City Daihen Co., Ltd. (72) Yoshihiro Fukuju, 2-1-11, Tagawa, Yodogawa-ku, Osaka Stockholders Company Daihen

Claims (3)

[Scope of utility model registration request] 1. A switching element after a commercial single-phase alternating current, to which either low voltage or high voltage having a ratio of approximately 1: 2 is selectively supplied, is input and the alternating input is rectified to direct current. In a power supply device for arc machining, which is inversely converted into high-frequency alternating current by an inverter circuit using the inverter, and the inversely converted high-frequency alternating current is converted into electric power suitable for arc machining, two series diodes each connected to the same polarity. And a third series circuit composed of two series capacitors are connected in parallel with each other,
The interconnection point of the diodes of the first series circuit is one input terminal to the commercial single-phase AC power supply, and the second
Input voltage for selectively connecting one of the interconnection point of the diode of the series circuit and the interconnection point of the capacitor of the third series circuit to the other input terminal for the commercial single-phase alternating current according to the input voltage. A power supply device for arc machining, comprising: a changeover switch; and a half-bridge type inverter circuit which receives the terminal voltages of the capacitors of the third series circuit as inputs. 2. A commercial single-phase alternating current, to which either low voltage or high voltage having a ratio of approximately 1: 2 is selectively supplied, is used as an input, and the alternating input is rectified into a direct current and then switched. In an arc machining power supply device of a system in which an inverter circuit using an element is used to inversely convert into high frequency alternating current and the inversely converted high frequency alternating current is converted into electric power suitable for arc machining, two series connected to each other having the same polarity. The first and second series circuits composed of diodes and the third series circuit composed of two series capacitors are connected in parallel to each other,
The interconnection point of the diodes of the first series circuit is one input terminal to the commercial single-phase AC power supply, and the second
Input voltage for selectively connecting one of the interconnection point of the diode of the series circuit and the interconnection point of the capacitor of the third series circuit to the other input terminal for the commercial single-phase alternating current according to the input voltage. A power supply device for arc machining, comprising: a changeover switch; and an inverter circuit that receives a terminal voltage of a capacitor of the third series circuit as an input and reverse-converts a DC input into a high-frequency AC. 3. A power supply device for arc machining according to claim 1, wherein a line filter is connected between the third series capacitor and the inverter circuit.