JPH0371218B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an arc power supply device installed in an arc device that can be driven with a plurality of input alternating currents having different voltages.

[Conventional technology]

Conventionally, arc devices such as arc welders and arc cutters that can be driven by either 100V or 200V commercial AC power supply have been equipped with an arc power supply device configured as shown in Figure 2, for example, as a constant current control type DC power supply device. is provided.

In addition, in Figure 2, 1 and 2 are 100V or
A pair of AC input terminals connected to a 200V single-phase AC power supply, 3 and 4 are two input changeover switches that are switched in conjunction, 100V contacts a, a', 200V
It consists of a two-contact changeover switch having contacts b and b', and the changeover piece is connected to input terminal 1.

5, 6, 7, and 8 are four diodes that rectify the input AC of input terminals 1 and 2, and the diode 5
The cathode of the diode 7 and the anode of the diode 6 are connected to the input terminal 1, the cathode of the diode 7 is connected to the cathode of the diode 6, and the cathode and anode of the diode 8 are connected to the anode of the diode 7 and the anode of the diode 5, respectively. At the same time, the connection point between the anode of diode 7 and the cathode of diode 8 is contact point b of switch 3.
It is connected to the input side rectifier that performs 100V voltage doubler rectification and 200V full-wave rectification.

9 and 10 are two smoothing capacitors connected in series, and the series circuit of both capacitors 9 and 10 is provided in parallel to the series circuit of diodes 7 and 8, and the connection point of both capacitors 9 and 10 is is connected to contact a of switch 3. Reference numerals 11 and 12 are two voltage equalizing resistors provided in parallel with the capacitors 9 and 10, respectively.
Together with this, they form an input-side smoothing circuit.

13 and 14 are two NPN type switching transistors, the emitter of transistor 13 and the collector of transistor 14 are connected, and the collector of transistor 13 is connected to the connection point p of the cathodes of diodes 6 and 7. At the same time, the emitter of the transistor 14 is connected to the connection point n of the anodes of the diodes 5 and 8.

15 is a high frequency output transformer equipped with a primary winding 15a and a secondary winding 15b with an intermediate tap, and one end of the primary winding 15a is connected to the transistors 13 and 14 via a DC removal capacitor 16. The other end of the primary winding 15a is connected to the connection point of the capacitors 9 and 10.

Two diodes 17 and 18 form an output rectifier, and their anodes are connected to both ends of the secondary winding 15b, respectively. 19 is a smoothing reactor whose one end is connected to the cathodes of diodes 17 and 18, 20 is a workpiece connected to the other end of the reactor 19, and 21 is a torch electrode that forms an arc load together with the workpiece 20. , is connected via a current detector 22 to the intermediate tap of the secondary winding 15b.

23 is the base of transistors 13 and 14.
This is an inverter drive circuit that outputs a 20KHz high frequency switching drive signal, and the start switch 24
The contact signal of the switch 24 and the current detection signal of the detector 22 are inputted, and the start and end of drive control of the transistors 13 and 14 are controlled based on the contact signal of the switch 24. 13 and 14 are controlled to feedback-control the load current flowing through the arc load to a constant current.

Reference numeral 25 designates a power transformer for the drive circuit 23, which has a primary winding 25a with an intermediate tap and a secondary winding 25b. The other end of the primary winding 25a is connected to the input terminal 2, and both ends of the secondary winding 25b are connected to the drive circuit 23.
It is connected to the.

Based on the input AC of 100V and 200V supplied to the input terminals 1 and 2, the switches 3 and 4 are set to contacts a, a' or contact b, by manual operation in advance.
b′.

That is, when the input AC is 100V power AC, switches 3 and 4 are switched to contacts a and a',
The input AC is connected to diodes 5, 6 and capacitor 9,
10 full-wave type double voltage rectification, the voltage is doubled and converted to DC, and a voltage of (100V) is applied between the connection points p and n.
×√2×2≒) A DC voltage of 290V is generated.

Then, the DC voltage between the connection points p and n is applied to the series circuit of the transistors 13 and 14, and the transistors 13 and 14 are high-frequency switched in reverse by the drive signal of the drive circuit 23, and the capacitor 16 is A high frequency voltage is applied to the primary winding 15a through the primary winding 15a.

Furthermore, high frequency AC is induced in the secondary winding 15b based on the high frequency voltage applied to the primary winding 15a, and the high frequency AC in the secondary winding 15b is caused by the diodes 17, 18 and the reactor 19. The object to be treated 20 and the torch electrode 21 are rectified and smoothed.
DC output is supplied to the arc load.

Also, the load current flowing through the arc load is detected by the detector 2.
from the detector 22 to the drive circuit 2.
3, a detection signal proportional to the load current is output.

By the way, the drive circuit 23 operates based on the output alternating current of the secondary winding 25b, and by inputting a contact signal for starting operation of the switch 24, the transistor 1
3 and 14 start drive control.

Then, the drive circuit 23 controls the switching frequencies of the transistors 13 and 14 so that the detection signal of the detector 22 matches an internally set reference signal, and the load current is feedback-controlled to a constant current.

On the other hand, if the input AC is a 200V power supply AC,
Switches 3 and 4 are switched to contacts b and b', and the input AC is converted to DC by full-wave rectification by diodes 5 to 8 and smoothing by capacitors 9 and 10, and in this case also between connection points p and n. (200V×√2≒)
A DC voltage of 290V is generated.

And transistors 13 and 14, transformer 1
5. The diodes 17 and 18, the reactor 19, the detector 22, and the drive circuit 23 supply DC output to the arc load in the same way as in the case of a 100V AC power source.

In addition, by switching the switch 4 to contact b', AC of the same voltage as in the case of 100V power supply AC is generated in the secondary winding 25b, and the output AC of the rated voltage is supplied to the drive circuit 23, and the drive circuit 23 works normally.

In addition, based on the contact signal of the start operation and stop operation of the switch 24, the start and stop of control of the transistors 13 and 14 by the drive circuit 23 is controlled, and the DC supply to the load is controlled.

Further, a conventional arc power supply device provided as a constant voltage control type DC power supply device is formed by substantially replacing the detector 22 in FIG. 2 with a voltage detector.

[Problem to be solved by the invention]

By the way, in the case of the conventional arc power supply device,
It is necessary to change the operating switches such as switches 3 and 4 according to the input AC voltage, which requires cumbersome operation, and if the switches 3 and 4 are mistakenly switched to contacts a and a' when the input AC is 200V, for example. However, there is a problem that each circuit part of the device may be damaged due to high input voltage.

In addition, in the case of an input AC of 100V, double voltage rectification is performed using a capacitor input type configuration, and at this time, based on the charging and discharging of the capacitor, only the approximately positive and negative peak level portions of the sinusoidal input AC are rectified. Even if the current flows through the capacitors 9 and 10 and is converted into high-frequency AC to improve conversion efficiency, for example, when inputting a small-capacity 100V single-phase AC power supply,
There is a problem in that sufficient DC cannot be supplied to the arc equipment, resulting in a low power factor of equipment including the power supply.Furthermore, the waveform distortion of the input AC occurs, which has an adverse effect on other equipment that operates on the same AC power supply. There is a problem with this.

The present invention provides an arc power supply device that improves operability by omitting switching operations depending on the voltage of input AC, improves utilization efficiency of input AC, and eliminates waveform distortion of input AC. The purpose is to

[Means to solve the problem]

Means for achieving the above object will be explained below with reference to FIG. 1, which corresponds to an embodiment.

The present invention includes a rectifier 26 as an input rectifier that rectifies input alternating current and converts it into direct current, a reactor 27 provided in series between the direct current output terminals of the rectifier 26, and a switching transistor 28 as a semiconductor switching element. , a smoothing capacitor section 30 into which the voltage at the connection point between the reactor 27 and the transistor 28 is injected via a diode 29 for preventing backflow; and a high-frequency converter section that converts the smoothed output of the smoothing capacitor section 30 into high-frequency alternating current. 31, an output rectifying and smoothing section 32 that rectifies and smoothes the high frequency alternating current and supplies it to the arc load, a voltage detector 33 that detects the smoothed voltage of the capacitor section 30, and a detection signal and a reference signal of the detector 33. Based on the above, the present invention provides an arc power supply device comprising an active filter control circuit 34 serving as a control section for supplying a drive signal for high frequency switching to the transistor 28 and controlling the smoothed voltage at a constant voltage. It is.

[Effect]

Therefore, based on the detection signal of the detector 33, the switching frequency of the transistor 28 is varied to control the smoothed voltage of the capacitor section 30 at a constant voltage, and the smoothed voltage is maintained at a constant voltage regardless of the input AC voltage. Based on the smoothed output of the constant voltage, a DC output is supplied to the arc load by the operation of the converting section 31 and the rectifying and smoothing section 32.

Then, due to the charging and discharging of the reactor 27 based on the high frequency switching of the transistor 28,
The accumulated energy of the reactor 27 is superimposed on the rectified output of the rectifier 26 and is repeatedly injected into the capacitor section 30, so that the rectified output of the rectifier 26 is repeatedly injected into the capacitor section 30.
0 charging is repeated and the usage rate of input AC is improved.

Furthermore, due to the high frequency switching of the transistor 28, the input AC is constantly flowing through the device through the rectifier 26, thereby preventing waveform distortion of the input AC.

〔Example〕

Next, the present invention will be described in a first embodiment showing one embodiment thereof.
This will be explained in detail with reference to figures.

In Fig. 1, the same symbols as in Fig. 2 indicate the same things, and 26 is a rectifier that rectifies the input AC of input terminals 1 and 2, and is composed of a full-wave or half-wave diode rectifier. A rectified output of a magnitude corresponding to the input AC is output from the positive and negative output terminals (+) and (-). 27 and 28 are reactors and NPN type switching transistors installed in series between the output terminals (+) and (-),
The collector of the transistor 28 forming the semiconductor switching element is connected to the output terminal (+) via the reactor 27, and the collector of the transistor 28 is connected to the output terminal (+) via the reactor 27.
The emitter No. 8 is connected to the output terminal (-) via the current detector 35. 36 is reactor 27,
This is a surge absorbing capacitor provided in parallel with the series circuit of the transistor 28 and the detector 35.

29 is a backflow prevention diode whose anode is connected to the connection point between the reactor 27 and the collector of the transistor 28; 37 and 38 are two smoothing capacitors forming the smoothing section 30; The connection point P between the cathode of the diode 29 and the capacitor 37 is connected to the collector of the transistor 13, and the capacitor 38 is connected in series with the emitter of the transistor 27.
A connection point N between and the emitter of the transistor 27 is connected to the emitter of the transistor 14. 3
A voltage detector 3 is provided between the connection points P and N, and outputs a voltage detection signal proportional to the smoothed voltage between the connection points P and N.

A DC/DC converter circuit 39 is supplied with the smoothed output of the smoothing section 30 generated between the connection points P and N, and supplies driving DC to an inverter drive circuit and an active filter control circuit, which will be described later. Reference numeral 34 denotes an active filter type control circuit for controlling the drive of the transistor 28, which is a digital control circuit driven by power supplied from the converter circuit 39, and is connected to the voltage detection signal of the detector 33 and the internally set smoothing voltage. A high frequency switching drive signal whose on period or frequency changes depending on the difference from the constant voltage control reference signal is supplied to the base of the transistor 28, and a current detection signal of the detector 35 and an internally set overload reference signal are supplied to the base of the transistor 28. Based on the comparison of
The on period or frequency of the switching drive signal is limited to a range that does not cause the transistor 28 to become overloaded.

40 is an inverter drive circuit provided in place of the drive circuit 23 in FIG.
3, 14, transformer 15, detector 22, etc., form a feedback control type high frequency converter 31, which is driven by power supplied from a converter circuit 39, operates in the same manner as the drive circuit 23, and converts the transistors 13, 14. Outputs a drive signal to. Reference numeral 32 denotes an output rectifying and smoothing section formed by diodes 17 and 18 and a reactor 19, which rectifies and smoothes the high frequency alternating current of the converting section 31.
Supplies constant current controlled DC to the arc load.

Then, the 100V or 200V power AC input to the input terminals 1 and 2 is rectified by the rectifier 26, and at this time, between the output terminals (+) and (-), there is a voltage proportional to the power AC, that is, the input AC. A rectified output of

In addition, the drive signal from the control circuit 34 causes the transistor 28 to perform high frequency switching at a frequency sufficiently higher than the AC power source, and during the ON period of the transistor 28, the transistor 28 is switched through the reactor 27.
A rectified output current flows through the reactor 27, and energy with the polarity in the direction of the arrow shown in the figure is accumulated in the reactor 27. During the off period of the transistor 29, a voltage with the opposite polarity is generated in the reactor 27 based on the accumulated energy. At this time, due to the high voltage obtained by superimposing the voltage of the reactor 27 on the voltage of the rectified output, the capacitor 3
7,38 are charged.

Then, the rectified output is smoothed by capacitors 37 and 38, and from the capacitor section 30 to the conversion section 31.
The smoothed output is supplied to the converter circuit 39.

By the way, the voltage between both ends of the capacitors 37 and 38, that is, the connection voltage between the connection points P and N is detected by the detector 33, and is transmitted from the detector 33 to the control circuit 34.
A voltage detection signal proportional to the smoothed voltage is output.

Then, the control circuit 34 digitally amplifies the error between the detection signal of the detector 33 and the constant voltage control reference signal of the smoothed voltage, and performs pulse width modulation or frequency modulation so that the detection signal matches the reference signal. The on period or frequency of the drive signal to the transistor 28 is variably controlled, and the voltage of the smoothed output is adjusted to the transistor 1.
3, 14, etc. are feedback controlled to a constant voltage within the voltage range that will not damage them.

Therefore, regardless of whether the input AC is 100V or 200V power supply AC, the rectified output input to the capacitor unit 30 is controlled by the reactor 27, transistor 28, and control circuit 34 so that the smoothed voltage becomes a constant voltage. is filter-limited, and is output from the filter section 30 to the conversion section 31, and the smoothed output, that is, the voltage of the DC output, is maintained at a constant voltage.

Note that in order to prevent damage to the transistor 28 due to overcurrent, the detection signal of the detector 35 is inputted to the control circuit 34 together with the detection signal of the detector 33, and the detection signal of the detector 35, that is, the current of the rectified output is proportional to the detection signal of the detector 35. Based on the digital comparison between the detected signal and the overload reference signal, the current flowing through the transistor 28 is controlled so that it does not exceed the current value of the reference signal.
Variation of the on period or frequency of the drive signal of the transistor 26 is limited.

Then, by the operation of the converting section 31 and the rectifying and smoothing section 32, constant current controlled DC is supplied to the arc load, and at this time, the input AC voltage is 100V, 200V.
In either case, the converting section 31, the rectifying and smoothing section 3
No damage such as 2 will occur.

Furthermore, based on the high frequency switching of the transistor 28 and the release of the stored energy of the reactor 27, the capacitors 37 and 38 are repeatedly charged and the input AC is utilized even in areas other than near the positive and negative peak values of the input AC. The power factor of the arc equipment improves by improving the usage efficiency of the arc equipment.

Furthermore, based on the high-frequency switching of the transistor 28, the input AC via the rectifier 26 constantly flows through the device, preventing waveform distortion of the input AC and adversely affecting other equipment.

In addition, in the above embodiment, the input AC is 100V.
Although we have explained the case where either power supply AC of 200V or 200V is input, the input AC may be either two types of AC different from the examples, for example, 200V or 400V AC, or any of three or more types of AC. Of course, this can be applied when the input is input.

Further, in the embodiment described above, the direct current supplied to the arc load is controlled at a constant current, but a voltage detector may be provided in place of the detector 22, and constant voltage control may be performed.

Further, the configuration of each part is not limited to the embodiment, and for example, a semiconductor switching element other than a switching transistor may be used as the semiconductor switching element.

Of course, the present invention can be applied to DC power supply devices for various arc devices such as arc welders, arc cutting machines, and arc lamp devices.

〔Effect of the invention〕

As described above, according to the arc power supply device of the present invention, by controlling the high frequency switching of the semiconductor switching element, the smoothed voltage of the smoothing capacitor section is controlled at a constant voltage, regardless of the input AC voltage, and the It is possible to improve operability by eliminating the corresponding switching operation, and the smoothing capacitor section is charged during the entire period of input AC using the stored energy of the reactor, improving the utilization efficiency of input AC and including the device. It is possible to improve the power factor of arc equipment, and to prevent waveform distortion of input AC, thereby preventing adverse effects on other equipment.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the arc power supply according to the present invention, and FIG. 2 is a block diagram of a conventional arc power supply. 26... Rectifier, 27... Reactor, 28... Switching transistor, 29... Diode for backflow prevention, 30... Smoothing capacitor section, 31... High frequency conversion section, 32... Output rectification and smoothing section, 33... Voltage detector, 34... Active Filter control circuit.

Claims (1)

[Scope of Claims] 1. An input rectifier that rectifies input alternating current and converts it into direct current; a reactor and a semiconductor switching element provided in series between the DC output terminals of the input rectifier; and the reactor and the switching element. a smoothing capacitor section into which the voltage at the connection point is injected through a diode for backflow prevention; a high frequency conversion section that converts the smoothed output of the smoothing capacitor section into high frequency alternating current; and a high frequency converting section that rectifies and smoothes the high frequency alternating current. an output rectifying and smoothing section that supplies the arc load; a voltage detector that detects the smoothed voltage of the capacitor section; and a voltage detector that supplies a drive signal for high-frequency switching to the switching element based on the detection signal of the detector and a reference signal. , and a control section that controls the smoothed voltage at a constant voltage.