JPH01152960A - Arc power source device - Google Patents

Abstract

PURPOSE:To prevent an arc power device against waveform distortion, by turning ON and OFF a switching element for charge and discharge control in a higher frequency than the power alternate current and by repeating the accumulation and discharging of energy with a reactor on the primary side. CONSTITUTION:An arc power source device is composed of a diode bridge rectifier 2 on the primary side, a smoothing circuit 3 on the primary side, switching elements 4-5 for high frequency conversion, a switching control circuit 6, a transformer 7, a rectifier 8 on the secondary side, a smoothing circuit 9 on the secondary side, a current detector 10, a high-frequency high- voltage generation circuit 12, etc. It supplies direct current and high-frequency high voltage to a load 11 superposedly. There, a reactor 13, a transistor 14 and a current-limiting resistance 15 are provided. A drive circuit 17 of the above transistor 14 detects the voltage of the rectifier 2 and the voltage drop across both terminals of the resistance 15 and drives the transistor 14 with a control signal of a PWM waveform (in a higher frequency than the power alternate current). These consist of an active filter 18. The capacitor 3 is thereby so fully charged at all times that the current quantity is increased.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention rectifies and smoothes power AC from a commercial single-phase power supply using a rectifier and a capacitor, and then converts the high-frequency AC into a high-frequency AC. This invention relates to a capacitor input type arc power supply device that smoothes and supplies direct current to an arc load.

[Conventional technology]

Conventionally, when driving DC arc equipment such as DC arc welding machines and DC arc bath breakers with household commercial single-phase power supplies,
As the power supply device, a capacitor input type arc power supply device shown in FIG. 4 is used.

Figure 4 shows an arc power supply device for DC arc welding using non-consumable electrodes such as tungsten electrodes.
A pair of power terminals connected to a single-phase power source for the section, (2)
is formed using a diode bridge rectifier etc.
Next-side rectifier, power supply terminal (la).

(Ib) rectifies and outputs the power AC. (3) is a primary side smoothing circuit formed using two smoothing capacitors (3a) and (3b)', and a capacitor (3a) is connected between the positive and negative output terminals f+) of the rectifier 12+ and t-1. ), (3
b) are connected in series to smooth the rectified output of the rectifier (21).

14t and 151 are two NPN type transistors forming a switching element for further frequency conversion; and transistor (
5) The collector and emitter are connected in series, and the transistors f41 and +51 perform high frequency switching in opposite phases based on the base voltage 1fflJ of the switching 1fflJ pure circuit (6).

In (7), one end of the primary winding (7a) is a transistor (4)
There is a transformer connected to the connection point between the emitter of and the collector of the transistor (5), the other end of the primary winding (7a) is connected to the connection point of the capacitors (3a) and (3b),
A high frequency alternating current based on high frequency switching of transistors +41 and +51 is applied to the primary winding d (7a).

+81fj Nidorance (7) center tap (tp)
This is a secondary side rectifier that rectifies the output AC of the secondary winding (7b) with three diodes (8a) for full-wave rectification,
(8b).

(8C) A diode (8a), (
The anode of the diode (8b) is connected to one end and the other end of the secondary winding (7b), and the anode of the diode (8C) forming a flywheel diode is connected to the center tap (tp), and the anode of the diode (8a) ~(8C)
A rectified output is formed with the anode of t1 being positive and the center tap (tl)' being negative.

(91 is a smoothing reactor (9a), a smoothing capacitor (9a)
b) is a secondary side smoothing circuit formed using Connected, reactor (9a), capacitor (9b) connection point? Positive, center tap (tp)
A smoothed output with 'r negative is output as a DC output to be supplied to the arc load.

This is a current detector installed between the connection point of the αG beam axle (9a) and the capacitor (9b) and the base material (lla) of the arc load [+11], which detects the load current flowing through the load (11). A current detection signal proportional to the load current is output to the control (b) path (6), and the transistor +41.
51 is controlled to control the load current at a constant current.

(121 is a high-frequency high-voltage generating circuit installed between one pole (llb) and center tap (tp) of the load Fl11, and a high-frequency high-voltage generating circuit [E is superimposed on the DC supplied to the load (111).

Then, the power alternating current of certain source terminals (Ia) and (lb) is rectified by the rectifier (21), and the rectified output of the rectifier 12 is connected to the capacitor (3a) of the smoothing circuit (3).
3b) and capacitors (3a), (3
A direct current obtained by rectifying and smoothing the power supply alternating current is generated between both ends of the series circuit in b).

Furthermore, control I! Transistors f4+ and +51 perform high frequency switching by base voltage control of the 12 circuit (6), high frequency alternating current is applied to the primary winding (7a) of the transformer +71, and high frequency alternating current is applied to the secondary winding (7b) of the transformer (7). Exchange occurs.

The output AC of the secondary winding (7b) is then connected to a rectifier (8).

Smoothing circuit (91) foil flow, smoothed, base material (lla
) is supplied to the load (11).

By the way, at the time of arc starting, the high frequency high voltage of the generation circuit 1121 is superimposed on the 1 page flow and is supplied to the load (111,
The high frequency high voltage of the generating circuit (121) generates the electrode (tlb
) and the base metal (lla).

When an arc is generated, the superposition of high frequency and high voltage is stopped, and only direct current from the smoothing circuit (92) is supplied to the load +II+, and arc welding such as TIG welding is performed.

Further, the DC load current supplied to the load til+ is detected by the detector αO, and the switching of the transistor +41.151 is controlled by the control circuit (6) based on the current detection signal of the detector αO, so that the load current is controlled by constant current.

In the case of the old power supply device shown in Fig. 4, the load current is feedback-controlled using the detector αa2 to perform constant current control, but in the case of the power supply device that performs constant voltage control 1i114, the detector A voltage detector is used in place of αO, and the load voltage is controlled at a constant voltage by feedback control based on the paper pressure detection signal of the voltage detector.

In addition, when performing bath seeding and fusing using a consumable electrode sound such as electric #g (llb), a high frequency and high voltage generating circuit such as generating circuit +121 is installed in order to quickly start the arc. Depending on the application, a high frequency high voltage generating circuit may not be provided.

[Problem that the invention seeks to solve]

By the way, in the case of the conventional capacitor input type arc power supply device shown in Fig. 4, since it is a capacitor input type, as shown in Fig. 5, only when the voltage Va of the power supply AC reaches approximately the positive or negative peak value, , the current Ia of the power supply AC is connected to the rectifier (21
, D7 flows through the electric circuit of the capacitors (3a) and (3b), and the capacitors (3a) and (3b) are charged.

In other words, if the output voltage of the rectifier 121 when it is in the negative state is the actual m va in FIG. As a result, a current flows from the rectifier (2) to the capacitor (Ja) (3b) as shown by the solid line 1a in the figure, based on the voltage level indicated by the one-dot broken line, and the voltage Va becomes approximately A current Ia with a sharp peak flows only when the positive and negative peak levels are reached.

Therefore, as is clear from FIG. 5, there is a problem in that the voltage waveform of the AC power source is distorted, which adversely affects other devices that all use the same power source.

In addition, commercial single-phase power supply (D'8-Fr power 1500VA (1
00V.

+5A), which is relatively small, and capacitors (3a), (3
Since charging in b) is performed only discretely, when used as a power supply for a plasma cutting machine, for example, a switching regulator configuration using transistors +41, +5+g and a transformer (7) can reduce the power supply efficiency to zero. Even if it is increased to about .9, the DC supplied to the load is 90■
.

10A 8 Only in summer, the power factor of the cutting machine is 90VXI
The OA is as low as 0.66 (medium 1...VAXo, 9), and there is a problem that sufficient cutting ability cannot be obtained.

In other words, this kind of conventional capacitor-input type arc power supply device that uses a single-phase power source is a capacitor-input type, and the power supply capacity is relatively small. There is a problem in that as the voltage decreases, the input voltage waveform becomes distorted and adversely affects other devices.

This invention has been made with the above-mentioned problems in mind.

[Means for solving the problems] Means for solving all of the above problems will be explained below using FIG. 1 corresponding to the embodiment.

This invention includes a primary side rectifier (2) for fully rectifying AC power of a commercial single-phase power supply, and smoothing capacitors (3a), (8b).
a primary side smoothing circuit (3) which is formed using 7
Transistor +41 as a switching element for high frequency conversion supplied to a). +51 and transformer (7) 2
The secondary side [rectifier (
8), and a secondary smoothing circuit (9) that smooths the rectified output of the rectifier (8) and supplies all of the output DC to the arc load (Ill).
A capacitor-input type arc power supply device 3 is equipped with a reactor (131) and a transistor A4 as a charging/discharging control switching element that switches at a lower frequency than the power supply AC in series with the current regulator [21]. We are taking technical measures.

[Effect]

Therefore, according to the present invention, based on the switching of the transistor circle, the reactor (131) repeatedly stores and releases energy at a frequency higher than the power supply AC, and the smoothing capacitors (aa) and (ab) are connected to the rectifier (131).
The rectified output of 21 and the released energy of the axle 031 are repeatedly charged at unnecessary intervals, and at this time, since the capacitors (3a) and (3b) are always sufficiently charged, the arc negative Tar ( The amount of output DC current supplied to m is increased compared to the conventional one, and the power factor of arc equipment using this power supply equipment is improved, and furthermore, the power supply AC current is constantly flowing through the entire device according to the switching of the transistor circle. The current waveform of power supply alternating current is improved, the voltage waveform is prevented from being distorted, and the technical problem is solved.

〔Example〕

Next, this invention will be explained in detail with reference to FIGS. 1 to 3 showing embodiments thereof.

3 in FIG. 1, the same symbols as in FIG.

It is an NPN type transistor installed in series between the (-) and the reactor (131 is the rectifier (2)
The emitter of the transistor (141) is inserted between the positive output terminal (+) and the smoothing circuit (3), and the emitter of the transistor (141) forms the switching element for charge/discharge control.
It is connected to the negative output terminal (-) of the rectifier (2) through the rectifier (2).

061 is a diode for preventing backflow, and its anode is connected to the connection point of the collector of the transistor circle of the handle 1131, and its cathode is connected to the collector of the transistor (4).

+171 is a drive circuit for the transistor (14),
The entire electron drop across the positive and negative terminals (voltage 3 between (-) and resistor 05) of the rectifier 121 is detected, and a switching control signal of the periodic variant described later or a constant period PW is detected.
An M-waveform switching control signal is supplied to the base of the transistor [41], and the transistor a4+ is driven for switching at a frequency sufficiently higher than the power supply AC. α ~ beam acdle 131, tiger 7 dista t141. It is an active filter formed by the resistor Q5), the diode Hg, and the Hatake wJ circuit [lη.

That is, the power supply device shown in FIG.'tA1 is formed by adding a filter (+8+k) having a reactor t+31.1-transistor L141-e to the power supply device shown in FIG.

, and 1, the drive circuit 07] is synchronized with the AC power source based on the voltage of the rectified output of the rectifier (2), that is, the voltage of the absolute waveform of the voltage of the AC power source shown by the solid line vb in FIG. A switching control signal for variably controlling the switching period of the transistor 041 is formed and supplied to the base of the transistor I so that the on period becomes longer in proportion to the voltage of the AC power source.

At this time, the transistor α is turned on and off repeatedly in each half cycle of the power supply AC, and as the voltage of the power supply AC approaches the positive and negative peak voltages, the on period of the transistor [+41 becomes longer.

Then, when the transistor circle is turned on, a current flows from the positive output terminal (+) of the rectifier (21) to the rectifier (21) through the actuator f13.transistor 1141. induce.

Next, when the transistor [+41 is turned off, a voltage with a polarity opposite to that shown in the reactor 031VC is generated, and at this time,
The capacitors (3a) and (3b) are charged by a high voltage obtained by adding the voltage of the reactor 03 to the voltage of the rectified output of the rectifier (2), and the rectifier]2) Karari Adle++
3+, diode ua, capacitor (3a), (3
b) Current flows through the rectifier 121 through k.

3. During load, transistor i41, f! +l
Based on the switching of the charged capacitor (3
a).

(3b) is discharged.

Further, due to the backflow prevention of the diode αG, even if the transistor H is turned on, the charging current of the capacitors (8a) and (3b) will not flow into the transistor circle.

Furthermore, based on the detection of the voltage drop across the resistor 05), the 1 drive circuit 071 also prevents the transistor 1141 from overcurrent.

Therefore, the transistor circle turns on and off in short cycles, for example, tn, tn+++ tr+4 in Figure 2.
Assuming that the transistor (141) is turned on, off, on, and off at -2°tnH, the energy stored in the reactor OJ is stored in the reactor (131) and released to the capacitors (3a) and (8b) in a short cycle. At this time, the rectified output current of the rectifier 121 changes into a triangular waveform whose peak value increases in proportion to the voltage at a shorter cycle than the AC voltage, as shown by the solid line ib in the figure.
The average value changes sinusoidally in proportion to the voltage waveform of the AC power source, as shown by the solid line lb' in the figure.

3. The broken line in FIG. 2 indicates the envelope waveform of the peak value of the triangular waveform described above.

Since the current of the rectified output of the rectifier 121 is based on the current of the power supply AC, in the case of FIG. 1, the current of the power supply AC is the rectifier i21. ! The waveform of the AC current Ib flowing through the device is improved to almost a sine wave, as shown in Figure 3.
At this time, no waveform distortion occurs in the voltage vb of the AC power source, and other devices using the same power source are not adversely affected.

In addition, during the entire period of AC power supply, the capacitors (3a) and (3b) are repeatedly charged by a voltage higher than the voltage corresponding to the stored energy of the reactor (131).
During load, the amount of DC current supplied from the smoothing circuit (9) to the load tllll increases compared to the conventional one, improving the power factor of arc equipment such as welding machines and bath IIfr machines. As a result of applying it to a plasma cutting machine by setting the efficiency of all the power supply devices except α to 90%, the power factor of the cutting machine improved to 95%, and at this time, the amount of current supplied to the load was 1500VAX0. 9x O, 9Xo,
95+ 1150VA (D output capacity and DC) Voltage 9
Based on 0V,] I 50VA/90V-i-1
iA, an increase of 28% compared to the conventional IOA.

Since the current supplied to the load increases and the power factor improves, the cutting capacity of a plasma cutting machine improves, and plasma cutting with high cutting capacity using all commercial single-phase power supplies = W. Can be done.

Incidentally, the same effect can be obtained by using a 1' WM wave control signal, that is, a control signal sound in which the ratio of the on period to the off period in a constant cycle changes, to drive the transistor (1).

Further, the switching frequency of the transistor [141] may be set to any frequency higher than the voltage v$ and the frequency of the tributary, and the higher the frequency, the higher the waveform improvement effect.

And rectifier +2! , +81. Smoothing circuit [31, (
Of course, the lectures such as No. 91 can be applied to various capacitor input type arc power supply devices different from the embodiments.

〔Effect of the invention〕

As described above, according to the arc power supply device of the present invention, based on the switching of the switching element for charge/discharge control, the accelerator is connected in series to the primary rectifier and stores and releases energy at a frequency higher than that of the power supply AC. At the same time, the energy released from the reactor charges the smoothing capacitor in the primary side smoothing port repeatedly in short cycles, so the amount of output DC current supplied to the arc load increases, and the power supply AC current increases. The waveform is improved and distortion of the sectional pressure waveform is prevented, the power factor of the arc-like device using the electrical device is improved, and an adverse effect on other equipment using the same power source can be prevented. It is.

[Brief explanation of the drawing]

Fig. 1 is a wiring diagram of one embodiment of the arc power supply device of the present invention, Figs. 2 and 3 are waveform diagrams for explaining the operation of Fig. 1, and Fig. 4 is a wiring diagram of a conventional arc power supply device. , 5th Hiroj
, and FIG. 6 are waveform diagrams for explaining the operation of FIG. 4, respectively. (Ia), (lb) ,, ゛Awakening source terminal, 121
, +81 ・= primary elevation 1, secondary rectifier, +31
, (91.= Primary side, secondary side smoothing circuit, (3a). (3b)... Smoothing capacitor, (41, +51... Transistor forming a switching element for frequency suppression conversion,
(Ill...Arc load, +131...Reactor, a4...Transistor forming a switching element for charge/discharge control. Agent: Patent attorney Fuji 1) Ryutabe No. 1 t, a cut out 3

Claims (1)

[Claims] (1) A primary rectifier that rectifies the power alternating current of a commercial single-phase power supply, a primary smoothing circuit that is formed using a smoothing capacitor and smoothes the rectified output of the primary rectifier, and a smoothing circuit that smooths the rectified output of the primary rectifier. a high-frequency conversion switching element that converts the output into high-frequency alternating current and supplies it to the primary winding of the transformer; a secondary rectifier that rectifies the output alternating current of the secondary winding of the transformer;
A capacitor input type arc power supply device comprising a secondary smoothing circuit that smooths the rectified output of the secondary rectifier and supplies an output DC to an arc load, the reactor being connected in series with the primary rectifier; An arc power supply device characterized by being provided with a charging/discharging control switching element that switches at a higher frequency than a power source alternating current.