JPS60226780A - Power source - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates generally to power supplies, and more particularly to electric power supplies particularly suited for supplying the series of current pulses required for pulse or spike welding. It is.

[Prior Art] Spike or pulse welding systems, which perform welding by sending high-frequency current pulses with a small pulse width to the workpiece to be welded, are currently widely used. A three-phase AC mVR system is used to increase the frequency of the welding pulse in order to apply a load current to the workpiece depending on the conditions of the welding operation.

In the above-mentioned type of system, the alternating current pulse is a three-phase power supply! It will be sent to each coil winding of the step-down transformer from the ground. Additionally, the current pulses generated in the secondary circuit of the transformer will be rectified before being sent to the welding electrode.

Previously, multiple individual-order windings had to be used in transformers because using a single winding would cause the current waveforms in each phase to overlap, effectively shorting between phases. .

It is known in the art to incorporate capacitors into the primary circuit of a step-down transformer in order to reduce the pulse width and increase the pulse amplitude. For example, U.S. Pat.
No. 43,698 discloses a pulse generation circuit that can be used in a three-phase AC power supply. This patent discloses that a plurality of discharge circuits are used, separated for each phase, which discharge circuits are connected correspondingly to the individual coils of the step-down transformer.

Each discharge circuit includes a dedicated capacitor for pulse compression and a discharge device such as an ignitron for charging and discharging the capacitor.

As disclosed in the aforementioned patents, the use of individual secondary coils and dedicated capacitors for each discharge circuit substantially increases the size and cost of the welding system. Furthermore, the use of multiple primary coils and primary circuits can lead to undesirable magnetic overlap reduction between these circuits.

[Disclosure 1 of the Invention According to the present invention, a pulse generation system for use in a three-phase pulse type welding machine includes three independent discharge circuits connected to a three-phase power supply by a △-Y connected transformer. .

Each discharge circuit includes a converter-controlled discharge device that outputs pulses to a common series circuit including a discharge capacitor and a single-primary coil of a step-down transformer. The secondary coil of the transformer is connected to a plurality of welding electrodes, to which small current pulses of Pulse 1] and high frequency current are sent.

[Object of the Invention] Therefore, the main object of the present invention is to provide a pulse type N source device for a welding system using a three-phase power source.

Another object of the invention is to provide a power supply device as described above in which the size of the circuit and the number of circuit elements can be substantially reduced.

Another object of the invention is to provide a power supply as described above using a single primary coil to which all three phases of AC power are applied, eliminating the resulting electromagnetic overlap reduction.

Yet another object of the present invention is to provide a power supply as described above in which each phase is independently discharged to the phase silver with respect to the neutral conductor.

Other objects of the invention will become apparent from the following description of embodiments of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the accompanying drawings, the present invention broadly encompasses a pulse generating power supply for producing high amplitude current pulses for use in spike or pulse welding equipment. A pulse oscillator or pulse generator is connected between the three-phase AC power source 10 and a pair of welding electrodes 80 that supply current pulses to a workpiece (not shown) to be welded. This pulse oscillator includes a step-down transformer 12 with a Δ-Y connection that lowers the voltage from a three-phase AC power supply from, for example, 460V to 220V. The transformer 12 has a Y-connected secondary circuit 16 and a power supply 1.
Coil 14 connected in delta fashion to the supply line of
A primary circuit consisting of a, 14b and 14c is included.

Secondary circuit 16 includes coils 16a, 16b, and 16c connected to a common or neutral terminal 18 in a Y-connection.

]Ile 16a.

16b, 16G are connected to lines 20, 22° and 2, respectively.
A portion of a discharge circuit configured corresponding to 4 is formed. Lines 20-24 are connected in series corresponding to a pair of ignitrons 26-30 connected in parallel. Each pair of ignitrons 26-30 has coils 16a and 16b.
, 16c are discharged in each half period of the corresponding phase. Therefore, as shown in FIG. 2, the ignitron 26 is supplied with a positive phase signal from the coil 16a.

The battery is discharged for each negative 1/2 cycle. Similarly, the ignitron 28 discharges over 1/2 period each of the positive and negative phases of B (17 phases), and the ignitron 30 discharges the positive phase of C.

Discharge each minus 1/2 period. The ignitrons 26-30 are controlled by corresponding discharge circuits 40-44 which cause the discharge ignitrons 26-30 to discharge at appropriate times or generate timing pulses. Has normal design or function. Discharge signals from discharge circuits 26-30 are sent alternately on lines 34-38. The discharge circuits 40-44 are in turn controlled by a microcomputer 50 having a program that operates the discharge circuits 40-44 to generate the necessary engine pulses. The half-wave outputs of ignitrons 26-30 are routed through common line 32 and lines 52. Capacitor 54. It is fed into a series circuit including a primary coil 64 of step-down transformer 62 and a neutral wire 76 connected to neutral terminal 18 of transformer 12 . Additional capacitors 56,58 are connected to capacitor 54 via switch 60 to increase the capacitance level of the series circuit.
selectively connected to the circuit. Furthermore, the tap 72 is connected to the primary coil 64 of the series circuit described above, and the plurality of taps 6
6-70 is a switch 74 for changing the connection between the primary circuit (coil) 64 and the secondary circuit (coil) 78 of the transformer 62;
is switched into a series circuit via. The 1/2 cycle sine wave output from each of the discharge circuits is used to continuously charge and discharge the capacitor 54. As best seen in FIG. 2, a voltage spike A across capacitor 54
+, B+, C+, A-, B-, C-, effectively reducing the width of the half-waveform voltage applied to the primary coil 64.

In this way, the voltage spike applied to the negative order coil 64 is a 1/2 sine wave (φA, φB, φ
B) does not cause the waveform overlap at 82 that occurs when it is applied to the negative coil 64. The overlap of the waveforms at 82 will cause a short between the phases, overloading the transformer 62 and potentially burning it out.

Microcomputer 50 and key 1 for reducing pulse width
7 pacitor 54 to control the discharge of each ignitron 26, 28, 30 by defining appropriate timing to deliver a total pulse to a common series circuit including the primary coil 64 in the step-down transformer. I can do it. This configuration of controlling the ignitron discharge not only increases the operational performance of the welding system, but can also substantially reduce welding costs. It should be noted that the use of a Δ-Y connection in the transformer 12, which includes a common or neutral line, does not reduce the number of ignitrons 26-30 that must be installed.

From the above description, it is clear that not only does the pulse oscillator described above reliably achieve the several objectives of the invention, but the method of achieving it is effective and economical. Therefore,
It is to be understood that the scope of protection that is necessary and to be afforded must extend to the matter recited in the claims and all equivalent matters which clearly fall within the scope of the present invention.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, and FIG. 2 is a graph showing a voltage waveform generated by the circuit shown in FIG. In the figure, 10 is a three-phase AC power supply, 12 is a step-down transformer, 14 is a primary circuit, 16 is a secondary circuit, 64 is a primary coil, 78 is a secondary coil, 26-30 is an ignitron, and 40 is a discharge circuit. , 50 is a control circuit. Patent applicant Nobuo Kinutani/Rg-2, patent attorney representing Weldax Incorporated

Claims (1)

[Scope of Claims] (1) 1st, 2nd, 2nd, 2nd, 3rd and 3rd 3. a third circuit; Second. The third circuits are connected in series to each of the first and third circuits. a fourth circuit including a capacitor that stores each amount of electric power continuously sent from the second and third circuits;
a transformer including a primary coil connected to said fourth circuit receiving electrical pulses from said capacitor; Second
．． and a control circuit for controlling the operation of a switch for continuously supplying current pulses from a third circuit through the secondary coil. (2) Each of the first and second switches are connected in parallel with each other to alternately connect the corresponding phase to the fourth circuit. A power supply device according to claim 1, including a second switch portion. (3) The control circuit controls the operation of the first and second switch portions. Claim 2, further comprising a first discharge circuit, a second discharge circuit, and a third discharge circuit connected to the switches of the second and third circuits, respectively, and a program computer for controlling the operation of these discharge circuits. power supply. (including a 41 common terminal and first, second and third circuits respectively connected to the common terminal, the fourth circuit and the primary coil are connected to the common terminal and the first, second and third circuits) (5) A plurality of taps each connected at different points along the longitudinal direction of the secondary coil; and a switch means for selectively connecting a plurality of taps to the common terminal. A first coil connected to the primary coil and the above common terminal. Second
and a Y-connection secondary coil including a third coil, each of which is connected in parallel, and three discharge circuits each connected to the secondary coil, and at least one a pulse forming circuit comprising a capacitor and a transformer having a single primary coil connected in series with the capacitor, the secondary coil and the capacitor being connected between the discharge circuit and a common terminal; Features a power supply device. (7) A plurality of capacitors in the pulse forming circuit, and means for selectively connecting the plurality of capacitors together with the second coil in order to enable various selections of capacitance in the pulse forming circuit. Claim 6
The electric a device described in Section 1. (8) The power supply device according to claim 6, which includes a program computer that controls the operation of the plurality of discharge circuits. (9) Each of the discharge circuits includes a pair of switches connected in parallel with each other and controllable alternately for switching with a corresponding phase of an alternating half period to the pulse forming circuit. A power supply device according to scope item 8.