JPH09277066A - Transistor system welding power source device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure substantial improvement in a tact speed by greatly curtailing charging time of a capacitor. SOLUTION: With a power source 1 changed from a conventional single phase AC input to a three phase AC input, a large reduction in ripple content is contrived for the DC output in an AC/DC converter 11. Consequently, the required capacity of a smoothing capacitor 12 is markedly reduced, greatly curtailing the charging time, substantially improving the generating efficiency per unit hour of the output current 101 transmitted under the control of a power MOSFET 13, thereby securing quickness in welding by a welding part 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transistor-type welding power source, and more particularly, to a transistor-type welding power source suitable for welding fine components such as electron guns and filaments and fine processing such as printed circuit board repair. Regarding the device.

[0002]

2. Description of the Related Art As a conventional welding power source apparatus for performing this kind of fine parts and fine processing, several hundreds to several thousand amperes (Amps) are formed by crimping an object to be welded between electrodes for welding, so-called welding heads. The welding current of a large current is sent to the welding head for an extremely short time of at most several ms, but the linearity and speed of the rise and fall times of this welding current are the welding quality of a fine work piece (workpiece). It becomes an important condition for securing.

The transistor type welding power supply device is a system for controlling the welding current based on the operation of a transistor capable of controlling a large current, and is a system for supplying the energy stored in the capacitor to the current by the transistor for welding. is there.

FIG. 3 is a characteristic diagram showing the relationship between welding current and welding time in various welding power supply devices. As is clear from FIG. 3, the transistor type a exhibits a welding current characteristic as a trapezoidal wave having a rapid rising and falling characteristics and preferable linearity, whereby a large suppression of excessive melting and splash at the time of welding. Therefore, it is possible to secure high-quality welding that ensures the welding of fine workpieces.

This means another capacitor system shown in FIG. 3 (a system in which the charging energy of the capacitor is released in a short time), an AC system using an AC waveform, or a switching of a three-phase full-wave rectified DC voltage. Even when compared with an inverter type d or the like which is converted to a high frequency and is supplied to welding as a low voltage direct current with a transformer or a rectifier, its superiority is clear.

FIG. 2 is a block diagram showing the configuration of a conventional transistor type welding power source device. The conventional transistor-based welding power supply device shown in FIG. 2 includes a welding part 2 for welding, a power supply part 4 as a welding current supply source for the welding part 2, a generation timing of welding current, and control for level adjustment. And a control unit 3 for performing the operation.

The welded portion 2 has a structure suitable for sandwiching an object to be welded by crimping and applying a large welding current in an extremely short time to effectively generate Joule heat. And a voltage detector 22 configured to connect a pickup wire to the welding head 21 and obtain a voltage difference between the two wires, and the detected voltage difference is sent to the control unit 3 as a detection voltage 201.

The power supply unit 4 uses a single-phase transformer 411 for converting a single-phase AC of AC100V into a predetermined AC voltage, and a thyristor as a rectifying element for receiving an output of the single-phase transformer 411 to obtain a desired DC output. Phase full-wave rectifier circuit 41
2 and a charge control circuit 413 that performs phase control (firing angle control) of the thyristor so as to control the output of the single-phase full-wave rectification circuit 412 to a desired value.
And a capacitor 42 that charges the output of the AC / DC converter 41, and a power MOS FET 43 that enables a current control exceeding 1 KA (kiloampere) by connecting a plurality of MOS FETs, for example, 10 MOSFETs in parallel. A current detector 44 that non-contactly detects a welding current as an output current by using a current detection element, for example, a Hall element, and sends it out as a detection current 401.

The above-described capacitor 42 includes smoothing for the DC output of the AC / DC converter 41 and stores electrical energy as a welding current source. Its discharge is controlled by the power MOS FET 43. 20,
The smoothing function described above is ensured by arranging ten capacitors having a capacity of about 000 μF in parallel.

The control section 3 has a key switch for inputting an operation command 301 for setting the entire operation mode,
An I / O interface that interfaces the operation command 301 input by the key switch to the internal device and also interfaces with an external device, and a C that incorporates a control program
A PU, a memory as a storage medium for processed data, and the like are provided.
From the voltage detector 22 of the weld 2
1 is provided for each, and the power MOS FET 43 of the power supply unit 4
A control voltage 304 as a gate voltage to be controlled is transmitted to control a welding current as a drain-source current of the power MOS FET 43.

Further, in FIG. 2, the contents of control by the control unit 3 are displayed on a monitor such as an LCD (not shown) as a monitor display output 302, and control information 30 is sent to an information processing device such as a computer.
3 and 3 are also shown.

With the above-described structure, welding is performed by the welded portion 2, and this welding also has the following three control methods. That is, it is constant voltage, constant current or constant power control.
Which of these control methods is to be set can be arbitrarily designated by pressing the above-mentioned key switch in consideration of the physical conditions of the object to be welded, the purpose of welding, and the like.

For example, in the case of fine processing for the purpose of welding to repair a copper pattern provided on a printed circuit board, constant voltage control is often adopted because it has little dependence on the width of the copper pattern. In this way, welding of fine parts and fine processing is performed.

[0014]

In the above-mentioned conventional transistor-type welding power supply device, it takes time to charge the capacitor existing as the energy storage source for supplying the welding current, and the number of weldings per unit time is determined. It has the drawback of having a limited tacked speed.

This is because a single-phase alternating current is used as a power source, and therefore the rectified output waveform contains many ripples. Therefore, in order to ensure a rectifying function in consideration of this point, the large-capacity capacitor as described above is used. It is necessary to arrange a large number of
For this reason, it is unavoidable that the time constant during charging also becomes large.

The normal takt speed is not possible twice or more / SEC although it varies depending on the welding current. It is desirable to increase this tact speed as much as possible in order to improve welding efficiency, especially if it is to be installed in automated equipment, it is desired to be 5 times / SEC or more, but unless the charging time of the capacitor is shortened. , This drawback cannot be solved.

An object of the present invention is to solve the above-mentioned drawbacks and to provide a transistor type welding power supply device capable of significantly reducing the charging time of a capacitor and ensuring a significant improvement in tact speed.

[0018]

The present invention has the following means in order to achieve the above object. That is, the first configuration of the present invention relating to the transistor type welding power source device is a transistor type welding power source device which is used as a welding power source for welding in microfabrication such as repairing fine parts and printed circuit boards. Then, each of the configurations (a) to (c) shown below is provided. (A) Welding work is performed in which the object to be welded is crimped and sandwiched and the welding current supplied from the outside is conducted to the object to be welded for a predetermined time to melt and bond the object to be welded by Joule heat. For welding a welding head including a pair of electrodes facing each other, and a voltage detector for detecting a voltage applied to the welding head. (B) A three-phase AC input of a predetermined voltage is converted to a DC output of a predetermined voltage. An AC / DC converter for conversion, a capacitor for smoothing a DC output of the AC / DC converter, and a generation timing and a level of a discharge current generated based on discharge of electric charges charged in the capacitor are controlled. A power MOS FET comprising a parallel connection structure of a plurality of MOSFETs interposed in an output line of the AC / DC converter for outputting a desired welding current to be supplied to a welding head of the welding portion. When,
A power supply unit including a current detector that is connected in series with the power MOS FET to detect the current value of the welding current. (C) A voltage detected by a voltage detector of the welding unit, and a current detector of the power supply unit. A key switch for inputting an operation command from outside, an I / O interface for performing input / output processing of the key switch, a CPU having a control program built therein, and a storage medium for storing processing data. And outputs a control voltage for controlling the power MOS FET of the power supply unit under the control of the control program, and secures control by the constant voltage, constant current or constant power for the welding head of the welding unit. Control unit

According to a second structure of the present invention, in the first structure, the AC / DC converter converts a three-phase AC input into a predetermined AC voltage, and the three-phase transformer. The three-phase full-wave rectification circuit for full-wave rectifying the AC output of the above-mentioned AC output into a DC output, and the DC output control circuit for converting the DC output output from the three-phase full-wave rectification circuit into a constant voltage.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION A discharge current obtained by charging a large-capacity capacitor and discharging this charge energy through a transistor such as a MOS FET in order to smooth a rectified DC output by converting the voltage of a single-phase power supply. The conventional transistor-type welding power supply that uses the welding current as the current can obtain a discharge current with a trapezoidal characteristic of steep rising and falling, and while ensuring high-quality welding that is not affected by the shape of the workpiece, It has the drawback that the charging time is long and the tact speed cannot be increased.

In the present invention, instead of the conventional single-phase AC power supply, a three-phase AC power supply is used as an input, and the DC output having a small ripple component, that is, ripple obtained by rectifying the voltage by converting this is smoothed by a capacitor. By adopting an embodiment in which a transistor is controlled to obtain a welding current, the ripple included in the rectified output is significantly reduced, the capacitance of the capacitor is reduced to about 1/10, and the charging time is significantly shortened. The tact speed is extremely fast.

[0022]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of a transistor type welding power source device according to an embodiment of the present invention. The transistor-type welding power supply device shown in FIG. 1 has a power supply unit 1 for supplying a low-voltage and large-current welding power supply with a three-phase AC input, a welding unit 2 for welding an object to be welded, and a power supply unit 1. And a control unit 3 for controlling the operation of.

The power supply unit 1 includes an AC / DC converter 11 for converting a three-phase AC input into a predetermined low-voltage DC output, and an AC / DC converter 11.
Capacitor 12 that smoothes the DC output of the DC converter 11
And a plurality of MOS FETs for controlling the output current value of the power supply unit 1 under the control of the control unit 3, a power MOS FET 13 having a parallel connection configuration of 10 MOS FETs in this embodiment, an output current of the power supply unit 1. And a current detector 14 for detecting a value.

The AC / DC converter 11 also performs a full-wave rectification on the secondary side output of the three-phase transformer 111 and the three-phase transformer 111 for converting the AC input of the three-phase AC of 200 V into a predetermined low voltage, and performs the predetermined rectification. It has a three-phase full-wave rectifier circuit 112 including a plurality of thyristors that generate output voltages as rectifying elements, and a DC output control circuit 113 that controls the output of the three-phase full-wave rectifier circuit 112 to a predetermined DC voltage.

Next, the operation of this embodiment will be described.
Since the welding portion 2 and the control portion 3 as the constituent elements other than the power supply portion 1 in this embodiment are basically the same as the welding portion 2 and the control portion 3 having the same reference numerals shown in FIG. A detailed description of each of these is omitted.

The AC / DC converter 11 is a three-phase transformer 1.
11 inputs AC 3-phase 200V and converts it into a predetermined low-voltage 3-phase AC. The three-phase full-wave rectifier circuit 112, which is arranged in each phase on the secondary side of the three-phase transformer 111 and has a thyristor as a rectifying element, has a gate electrode (G) controlled by the DC output control circuit 113 and has a predetermined low voltage. In this embodiment, DC24V is output.

The DC output control circuit 113 receives the secondary side output of the three-phase transformer 111 and responds to the voltage fluctuations by A
The gate electrode (G) of the thyristor of the three-phase full-wave rectifier circuit 112 is controlled so that the DC output of the C / DC converter 11 is maintained at a constant voltage.

Thus, AC / DC utilizing three-phase alternating current
The ripple voltage included in the DC output of the converter 11 is significantly lower than that in the case where single-phase alternating current is used.

The ratio of the ripple voltage is expressed by the ripple content ratio γ as follows. Here, ripple content rate γ = (effective value of ripple component included in DC output current /
It is expressed as (average value of output current) × 100 (%). For example, γ in the case of single-phase full-wave rectification is 48.3%, whereas γ in the case of three-phase full-wave rectification is 4.2% and 1 /
It drops to 10 or less.

In the case of the single-phase alternating current, the capacitor 12 has a remarkably large ripple content compared with the case of the three-phase alternating current. Therefore, it is necessary to use a large-capacity capacitor for smoothing, and high quality welding is required. To secure the processing power supply, for example, 20,
This has been a cause of increasing the capacity of the smoothing capacitor having ten 000 μF capacitors in parallel. This is
The charging time of the smoothing capacitor was increased and the upper limit of the tact speed was limited.

In the present embodiment, the capacitance value to be given to the capacitor 12 is 1/10 or less of the conventional value, and therefore the charging time is 1/10 or less. As a result, the takt speed can be theoretically about 10 times faster, and the efficiency of the welding process can be improved and the automatic equipment of the transistor type welding power source can be installed.

The power MOS FET 13 controls the output current 101 of the power supply unit 1 to a predetermined level while being controlled by the control voltage 304 received from the control unit 3. The current detector 14 that uses the Hall element as a non-contact type current detection sensor detects the value of the output current 101 and sends it as the detected current 102 to the control unit 3.

In the welding section 2, the welding head 21 performs welding processing on the object to be welded, the voltage detector 22 detects the applied voltage of the welding head 21, and sends the detected voltage 201 to the control section 3.

The control section 3 inputs the operation command 301, receives the detection current 102 and the detection voltage 201, controls the power MOS FET 13, and outputs the monitor display output 302 and the control information 303. In this way, it is possible to realize a transistor-type welding power source device with a significantly increased tact speed.

[0035]

As described above, according to the present invention, in the transistor type welding power source device, by changing the input AC power source to a three-phase AC power source, it is possible to secure a remarkably high takt speed of welding. Have.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a transistor type welding power source device according to an embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a conventional transistor welding power source.

FIG. 3 is a characteristic diagram showing the relationship between welding current and welding time in various welding power supply devices.

[Explanation of symbols]

 1 Power Supply Section 2 Welding Section 3 Control Section 11 AC / DC Converter 12 Capacitor 13 Power MOS FET 14 Current Detector 111 Three-Phase Transformer 112 Three-Phase Full-Wave Rectifier Circuit 113 DC Output Control Circuit

Claims (2)

[Claims] 1. A transistor-type welding power source device comprising the following components, which is used as a welding power source for welding in fine processing such as repairing fine parts and printed circuit boards. (A) Welding work is performed in which the object to be welded is crimped and sandwiched and the welding current supplied from the outside is conducted to the object to be welded for a predetermined time to melt and bond the object to be welded by Joule heat. For welding a welding head including a pair of electrodes facing each other, and a voltage detector for detecting a voltage applied to the welding head. (B) A three-phase AC input of a predetermined voltage is converted to a DC output of a predetermined voltage. An AC / DC converter for conversion, a capacitor for smoothing a DC output of the AC / DC converter, and a generation timing and a level of a discharge current generated based on discharge of electric charges charged in the capacitor are controlled. A power MOS FET comprising a parallel connection structure of a plurality of MOSFETs interposed in an output line of the AC / DC converter for outputting a desired welding current to be supplied to a welding head of the welding portion. When,
A power supply unit including a current detector that is connected in series with the power MOS FET to detect the current value of the welding current. (C) A voltage detected by a voltage detector of the welding unit, and a current detector of the power supply unit. A key switch for inputting an operation command from outside, an I / O interface for performing input / output processing of the key switch, a CPU having a control program built therein, and a storage medium for storing processing data. And outputs a control voltage for controlling the power MOS FET of the power supply unit under the control of the control program, and secures control by the constant voltage, constant current or constant power for the welding head of the welding unit. Control unit 2. The AC / DC converter includes a three-phase transformer for converting a three-phase AC input into a predetermined AC voltage, and a three-phase full-wave rectifying the AC output of the three-phase transformer into a DC output. The transistor type welding power supply device according to claim 1, further comprising: a wave rectification circuit and a DC output control circuit that converts the DC output output from the three-phase full-wave rectification circuit into a constant voltage.