CN1575902A

CN1575902A - Plasma arc electric power apparatus

Info

Publication number: CN1575902A
Application number: CN 200410062308
Authority: CN
Inventors: 田中和裕; 远藤靖知
Original assignee: Daihen Corp
Current assignee: Daihen Corp
Priority date: 2003-07-01
Filing date: 2004-07-01
Publication date: 2005-02-09
Anticipated expiration: 2024-07-01
Also published as: CN100464926C; JP2005066603A

Abstract

A plasma arc power supply device comprises a three-phase genuine bridge rectifying circuit made of a first thyristor element to a sixth thyristor element, a three-phase genuine bridge-phase control circuit outputting a first phase-control signal group phase-controlling the first thyristor element to the third thyristor element and a second phase-control signal group phase-controlling the fourth thyristor element to the sixth thyristor element, and a pilot-arc generation circuit made of a seventh thyristor element to a ninth thyristor element. In the plasma arc power supply device, a pilot arc made by small electric current is generated by means of the pilot-arc generation circuit when output current is zero, a main arc made by large current is generated by means of the three-phase genuine bridge rectifying control circuit when detecting flow of electric current, and then, the pilot arc is vanished.

Description

Plasma arc electric power apparatus

Technical field

The present invention relates to a kind of plasma arc electric power apparatus that cuts off the plasma cutting machine of mother metal by plasma arc that is used in.

Background technology

The plasma cutting machine as Japan specially permit shown in No. 2711984 communique like that, it constitutes: plasma is cut off with under the section and electrode state of contact of cutter, between this section and the electrode by the little electric current of plasma power supply unit feeding, then, while supply with plasma gas and make section break away from electrode and between this section and electrode, pilot arc takes place.

Fig. 9 is an example of the electrical connection graph of former plasma arc electric power apparatus.

Among Fig. 9, plasma arc electric power apparatus comprises three-phase transformer IN, the pure bridge commutating circuit of three-phase PB, the first thyristor driving circuit SD1, the second thyristor driving circuit SD2, the pure electric bridge of three-phase position phase control circuit PC.

The input side of three-phase transformer IN is connected on the commercial ac power source, and outlet side is connected on the pure bridge commutating circuit of the three-phase PB.

The second support arm that the pure bridge commutating circuit of three-phase PB is the first support arm that will be made of the first Thyristor SR1 of the first terminal of the primary side that is connected to three-phase transformer IN and the 4th Thyristor SR4 that is connected above-mentioned tie point, be made of the second Thyristor SR2 and the 5th Thyristor SR5 that is connected above-mentioned tie point of the second terminal of the primary side that is connected to three-phase transformer IN and the 3rd support arm that is made of the 3rd Thyristor SR3 of the 3rd terminal of the primary side that is connected to three-phase transformer IN and the 6th Thyristor SR6 that is connected above-mentioned tie point in addition three phase bridge connect and form.

The pure electric bridge of three-phase position phase control circuit PC begins action when input initiating signal Ts, generate the position control mutually the IGCT element (the first IGCT element SR1 to the, three IGCT element SR3) of first support arm to the, three support arm upsides (below, these IGCT elements are called the upside support arm) first phase control signal Pc1 and output to the first thyristor driving circuit SD1, generating the position controls second phase control signal Pc2 of the IGCT element (the 4th IGCT element SR4 to the six IGCT element SR6) of first support arm to the, three support arm downsides (below, these IGCT elements are called the downside support arm) mutually and outputs to the second thyristor driving circuit SD2.

The first thyristor driving circuit SD1 is according to the input of first phase control signal Pc1, generate the first gate signal S1, the second gate signal S2 and the 3rd gate signal S3 of each gate pole of the control first IGCT element SR1, second IGCT element SR2 and the 3rd IGCT element SR3, they are input to the gate pole of the first IGCT element SR1, the first IGCT element SR2 and the 3rd IGCT element SR3 respectively.

The second thyristor driving circuit SD2 is based on second phase control signal Pc2, generate the 4th gate signal S4, the 5th gate signal S5 and the 6th gate signal S6 of each gate pole of control the 4th IGCT element SR4, the 5th IGCT element SR5 and the 6th IGCT element SR6, they are input to the gate pole of the 4th IGCT element SR4, the 5th IGCT element SR5 and the 6th IGCT element SR6 respectively.

The pure bridge commutating circuit of three-phase PB by the first gate signal S1 to the, six gate signal S6 control the first IGCT element SR1 to the, six IGCT element SR6 conducting, interdict and carry out rectification action.

During the pure bridge commutating circuit of starting three-phase PB, because the section CP of cutter contacts with electrode EL, on the other hand, machined object CW and cutter break away from, so little electric current is from the pure bridge commutating circuit of three-phase PB flow through section CP, the electrode EL of cutter and guiding supply circuit (circuit that is made of first resistor R 1 and second resistor R 2).

Then, when plasma gas is supplied to cutter and makes electrode EL break away from section CP, between section CP and the electrode EL pilot arc takes place.This pilot arc is in generation, machined object CW is near cutter, main arc takes place from the pure bridge commutating circuit of three-phase PB flow through section CP, the machined object CW of cutter and main supply circuit (circuit that is made of output current detection circuit CT, IGCT SR10 and direct current reactance coil DCL) between the section CP of cutter and the machined object CW in big electric current.

In the plasma arc electric power apparatus in the past, little electric current is behind the pure bridge commutating circuit of three-phase PB output and generation pilot arc (pilot arc), in the generation of this pilot arc, machined object CW is near cutter and main arc takes place, big electric current is necessary to make the semiconductor element of jumbo semiconductor element as the first IGCT element SR1 to the, the six IGCT element SR6 that constitute the pure bridge commutating circuit of three-phase PB from the pure bridge commutating circuit of three-phase PB output and in order to keep main arc.

Jumbo semiconductor element is usually because profile is big, price is high, so the problem points that can not realize the plasma arc electric power apparatus miniaturization is arranged.And, when producing cutting in main arc takes place, high-tension crest voltage takes place, constitute the downside support arm semiconductor elements such as the 3rd IGCT element to the six IGCT elements also produce and apply the such problem points of crest voltage.

Summary of the invention

Its purpose of the present invention is to provide releasing or suppresses the above-mentioned plasma arc electric power apparatus of the problem points of technology in the past.

Plasma arc electric power apparatus provided by the invention comprises

For the first IGCT element of the 4th IGCT element and the first terminal of the primary side that is connected to three-phase transformer is connected and first support arm that forms at above-mentioned connected mid point, the second IGCT element of the 5th IGCT element and second terminal of the primary side that is connected to above-mentioned three-phase transformer is connected and second support arm that forms at above-mentioned connected mid point, with the 3rd IGCT element of the 6th IGCT element and the 3rd terminal of the primary side that is connected to above-mentioned three-phase transformer is connected and the 3rd support arm that forms carries out the pure bridge commutating circuit of three-phase that three phase bridge is formed by connecting at above-mentioned connected mid point; With

Carry-out bit is controlled first of upside support arm that the first IGCT element to the, the three IGCT elements by the pure bridge commutating circuit of above-mentioned three-phase constitute mutually and is controlled second the pure electric bridge of three-phase position phase control circuit of controlling sets of signals mutually that sets of signals and position are controlled the downside support arm that the 4th IGCT element to the six IGCT elements by the pure bridge commutating circuit of above-mentioned three-phase constitute mutually mutually

During the input initiating signal, export first of the pure electric bridge of above-mentioned three-phase position phase control circuit and control mutually that sets of signals is controlled sets of signals mutually with second and the position is controlled the pure bridge commutating circuit of above-mentioned three-phase mutually, simultaneously, the section and the electrode of cutter become contact condition, the guiding supply circuit of the pure bridge commutating circuit of above-mentioned three-phase by constituting by resistor, the little electric current of energising predetermined value between above-mentioned section and above-mentioned electrode, then supply with plasma gas, when above-mentioned electrode and above-mentioned section disengaging and generation pilot arc, after above-mentioned pilot arc takes place, the pure bridge commutating circuit of above-mentioned three-phase is by main supply circuit, main arc also takes place in the big electric current of energising predetermined value, it is characterized in that, also comprise:

By the 7th IGCT element of the mid point that is connected in above-mentioned first support arm, be connected in above-mentioned second support arm mid point the 8th IGCT element and be connected in the pilot arc generative circuit that the 9th IGCT element of the mid point of above-mentioned the 3rd support arm constitutes; With

When above-mentioned main supply is zero for the output current of circuit; When above-mentioned first phase control signal group is input to the upside support arm of the pure bridge commutating circuit of above-mentioned three-phase; Above-mentioned second phase control signal group is input to above-mentioned pilot arc generative circuit; When the above-mentioned main supply of then switching on is given the output current of circuit; The guiding of the downside support arm of the pure bridge commutating circuit of above-mentioned three-phase/main electric arc commutation circuit is switched and be input to above-mentioned second phase control signal group from above-mentioned pilot arc generative circuit

During the input initiating signal, when above-mentioned first is controlled sets of signals mutually and is input to the upside support arm of the pure bridge commutating circuit of above-mentioned three-phase, control sets of signals mutually with above-mentioned second and be input to above-mentioned pilot arc generative circuit, by above-mentioned guiding supply circuit, power-on boot arc current between above-mentioned section and the above-mentioned electrode, then supply with plasma gas, described electrode and described section break away from the generation pilot arc, detecting the above-mentioned guiding supply circuit of shunt current process of above-mentioned pilot arc electric current, the shunting supply circuit, main supply circuit and when machined object flows between electrode, control the downside support arm that sets of signals is input to the pure bridge commutating circuit of above-mentioned three-phase mutually with above-mentioned second, by switch on big electric current and main arc takes place of above-mentioned main supply circuit, pilot arc is disappeared.

Preferably, the first IGCT element to the, the three IGCT elements of the pure bridge commutating circuit of above-mentioned three-phase can be replaced as the 1st diode to the 3 diodes and form three-phase mixed electrical bridge rectification circuit, the pure bridge commutating circuit of above-mentioned three-phase is replaced as above-mentioned three-phase mixed electrical bridge rectification circuit.

Preferably, can on above-mentioned shunting supply circuit, design the 4th diode.

Preferably, the 5th diode can be designed on above-mentioned guiding supply circuit, design the 4th diode on above-mentioned shunting supply circuit.

About further feature of the present invention and advantage, below after the explanation embodiments of the present invention, meeting is clearer.

Description of drawings

Fig. 1 is the electrical connection graph of the plasma arc electric power apparatus of embodiments of the invention 1.

Fig. 2 is the oscillogram of the action of explanation plasma arc electric power apparatus shown in Figure 1.

Fig. 3 is the electrical connection graph of the plasma arc electric power apparatus of embodiment 2.

Fig. 4 is the oscillogram of the action of explanation plasma arc electric power apparatus shown in Figure 3.

Fig. 5 is the electrical connection graph of the plasma arc electric power apparatus of embodiment 3.

Fig. 6 is the oscillogram of the action of explanation plasma arc electric power apparatus shown in Figure 5.

Fig. 7 is the electrical connection graph of the plasma arc electric power apparatus of embodiment 4.

Fig. 8 is the electrical connection graph of the plasma arc electric power apparatus of embodiment 5.

Fig. 9 is electrical connection graph one example of former plasma arc electric power apparatus.

The specific embodiment

Below, about the preferred embodiment of the present invention, specifically describe with reference to drawing.

Fig. 1 relates to the electrical connection graph of the plasma arc electric power apparatus of embodiments of the invention 1.

Plasma arc electric power apparatus shown in Figure 1 is the supply unit that has eliminated the IGCT element SR10 in the former plasma arc electric power apparatus shown in Figure 9 and appended pilot arc generative circuit PG, guiding/main arc commutation circuit SW and the 3rd thyristor driving circuit SD3.

That is, the plasma arc electric power apparatus that relates to embodiment 1 comprises three-phase transformer IN, the pure bridge commutating circuit of three-phase PB, pilot arc generative circuit PG, the first thyristor driving circuit SD1, the second thyristor driving circuit SD2, the 3rd thyristor driving circuit SD3, guiding/main arc commutation circuit SW and the pure electric bridge of three-phase position phase control circuit PC.

Among Fig. 1, three-phase transformer IN is the transformer that commercial ac power source is transformed to the voltage that is fit to electric arc processes.

The pure bridge commutating circuit of three-phase PB comprise first support arm that the first IGCT element SR1 and the 4th IGCT element SR4 be connected in series and, second support arm that is connected in series of the second IGCT element SR2 and the 5th IGCT element SR5 and, the 3rd support arm that is connected in series of the 3rd IGCT element SR3 and the 6th IGCT element SR6.

The tie point of the first IGCT element SR1 and the 4th IGCT element SR4 (mid point of first support arm) is connected on the first terminal of primary side of three-phase transformer IN, the tie point of the second IGCT element SR2 and the 5th IGCT element SR5 (mid point of second support arm) is connected on second terminal of primary side of three-phase transformer IN, and the tie point (mid point of the 3rd support arm) of the 3rd IGCT element SR3 and the 6th IGCT element SR6 is connected on the 3rd terminal of primary side of three-phase transformer IN.

Pilot arc generative circuit PG by the mid point that is connected to first support arm (promptly, the first terminal of the primary side of three-phase transformer IN) the 7th IGCT element SR7, be connected to second support arm mid point (promptly, second terminal of the primary side of three-phase transformer IN) the 8th IGCT element SR8 and the 9th IGCT element SR9 that is connected to the mid point (that is the 3rd terminal of the primary side of three-phase transformer IN) of the 3rd support arm constitute.The negative electrode of the 7th IGCT element SR7 to the seven IGCT element SR7 interconnects, and its tie point is connected an end (end of first resistor R 1) of guiding supply circuit.The other end (end of second resistor R 2) of guiding supply circuit is connected on the section CP by guide terminal PT.

The downside support arm of the pure bridge commutating circuit of three-phase PB and mother metal are with being provided with direct current reactance coil DCL and output current detection circuit CT between the terminal MT and forming main supply circuit.The direct current reactance coil DCL of main supply circuit and the tie point of output current detection circuit CT are connected with first resistor R 1 of guiding supply circuit and the tie point of second resistor R 2.

Output current detection circuit CT detects and flows to the electric current of main supply circuit and output current detection signal Ct is outputed to guiding/main arc commutation circuit SW.Mother metal has connected machined object CW with terminal MT.

The pure electric bridge of three-phase position phase control circuit PC begins action when input initiating signal Ts; First the phase control signal Pc1 that generates the first Thyristor SR1 to the, the three Thyristor SR3 of position phase control upside support arm also outputs to the first thyristor driving circuit SD1, generate the 4th Thyristor SR4 to the six Thyristor SR6 of position phase control downside support arm and pilot arc generative circuit PG the 7th Thyristor SR7 to the nine Thyristor SR9 second phase control signal Pc2 and output to the second thyristor driving circuit SD2 or the 3rd thyristor driving circuit SD3 by guiding/main electric arc commutation circuit SW.

Guiding/main arc commutation circuit SW is input to the second thyristor driving circuit SD2 when bigger than predetermined value, switching to a side from the value of the output current detection signal Ct of output current detection circuit CT input with second phase control signal Pc2.Guiding/main arc commutation circuit SW than predetermined value hour, switches to the b side in the value of output current detection signal Ct, and second phase control signal Pc2 is input to the 3rd thyristor driving circuit SD3.

The first thyristor driving circuit SD1 is according to the input of first phase control signal Pc1, generate the first gate signal S1, the second gate signal S2, the 3rd gate signal S3 of each gate pole of controlling the first IGCT element SR1, the second IGCT element SR2 and the 3rd IGCT element SR3 respectively, and be input to the gate pole of the first IGCT element SR1, the first IGCT element SR2, the 3rd IGCT element SR3 respectively.

The second thyristor driving circuit SD2 is according to second phase control signal Pc2 by guiding/main arc commutation circuit SW input, generate the 4th gate signal S4, the 5th gate signal S5, the 6th gate signal S6 of each gate pole of controlling the 4th IGCT element SR4, the 5th IGCT element SR5 and the 6th IGCT element SR6 respectively, and be input to the gate pole of the 4th IGCT element SR4, the 5th IGCT element SR5, the 6th IGCT element SR6 respectively.

The 3rd thyristor driving circuit SD3 is according to second phase control signal Pc2 by guiding/main arc commutation circuit SW input, generate the 7th gate signal S7, the 8th gate signal S8, the 9th gate signal S9 of each gate pole of controlling the 7th IGCT element SR7, the 8th IGCT element SR8 and the 9th IGCT element SR9 respectively, and be input to the gate pole of the 7th IGCT element SR7, the 8th IGCT element SR8, the 9th IGCT element SR9 respectively.

Fig. 2 is the oscillogram of the action of explanation plasma arc electric power apparatus shown in Figure 1.The waveform of Fig. 2 (A) is represented the waveform of initiating signal Ts, and the waveform of Fig. 2 (B) is represented the waveform of the first gate signal S1, and the waveform of Fig. 2 (C) is represented the waveform of the second gate signal S2, and the waveform of Fig. 2 (D) is represented the waveform of the 3rd gate signal S3.The waveform of Fig. 2 (E) is represented the waveform of the 4th gate signal S4, the waveform of Fig. 2 (F) is represented the waveform of the 5th gate signal S5, the waveform of Fig. 2 (G) is represented the waveform of the 6th gate signal S6, the waveform of Fig. 2 (H) is represented the waveform of the 7th gate signal S7, the waveform of Fig. 2 (I) is represented the waveform of the 8th gate signal S8, and the waveform of Fig. 2 (J) is represented the waveform of the 9th gate signal S9.In addition, the waveform of Fig. 2 (K) is represented the waveform of gas signal Ar, and the waveform of Fig. 2 (L) is represented the waveform of output current detection signal Ct, and the waveform of Fig. 2 (M) is represented the voltage waveform Vo between electrode EL and the machined object CW.

During moment t=t1, when the initiating signal Ts shown in Fig. 2 (A) is imported into the pure electric bridge of three-phase position phase control circuit PC, the pure electric bridge of three-phase position phase control circuit PC begins action, first phase control signal Pc1 shown in Figure 1 outputed to the first thyristor driving circuit SD1, second phase control signal Pc2 outputed to guiding/main arc commutation circuit SW.

The first thyristor driving circuit SD1 is according to the input of first phase control signal Pc1, generate the first gate signal S1 that two pulses by having 60 ° phasic difference shown in Fig. 2 (B) constitute and, the second gate signal S2 that constitutes of two pulses shown in Fig. 2 (C) by having 60 ° phasic difference and, the 3rd gate signal S3 that constitutes of two pulses shown in Fig. 2 (D) by having 60 ° phasic difference, and output to the gate pole of the first IGCT element SR1, the second IGCT element SR2, the 3rd IGCT element SR3 successively respectively.In addition, the first gate signal S1 to the, three gate signal S3 have 60 ° phasic difference respectively.

Constantly during t=t1, because output current does not flow through main supply circuit, so be zero from the value of output current detection signal Ct output current detection circuit CT output, shown in Fig. 2 (L).Because the value of output current detection signal Ct is than predetermined value hour, guiding/main arc commutation circuit SW is switched to the b side, so during moment t=t1, second the phase control signal Pc2 that is imported into guiding/main arc commutation circuit SW from the pure electric bridge of three-phase position phase control circuit PC is imported into the 3rd thyristor driving circuit SD3.

Therefore, because when initiating signal Ts is imported into the pure electric bridge of three-phase position phase control circuit PC, the 3rd IGCT element SR3 to the six IGCT element SR6 of downside support arm become closed condition, so the pure bridge commutating circuit of three-phase PB is failure to actuate, rectification circuit (hereinafter referred to as " pilot arc rectification circuit ") the beginning rectification action that the first IGCT element SR1 to the, the three IGCT element SR3 of the pure bridge commutating circuit of usefulness three-phase PB upside support arm and the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG constitute.

The 3rd thyristor driving circuit SD3 is according to the input of second phase control signal Pc2, generate the 7th gate signal S7 that two pulses by having 60 ° phasic difference shown in Fig. 2 (H) constitute and, the 8th gate signal S8 that constitutes of two pulses shown in Fig. 2 (I) by having 60 ° phasic difference and, the 9th gate signal S9 that constitutes of two pulses shown in Fig. 2 (J) by having 60 ° phasic difference, and output to the gate pole of the 7th IGCT element SR7, the 8th IGCT element SR8, the 9th IGCT element SR9 successively respectively.

By the first gate signal S1 to the, three gate signal S3, the first IGCT element SR1 to the, the three IGCT element SR3 of the pure bridge commutating circuit of three-phase PB upside support arm quilt is scratch start successively.By the 7th gate signal S7 to the nine gate signal S9, pilot arc generative circuit PG the 7th IGCT element SR7 to the nine IGCT element SR9 quilt is scratch start successively.Thus, (for example 20A～30A) is fed between section CP and the electrode EL with first resistor R 1 and second resistor R 2 of rectification circuit by the guiding supply circuit from pilot arc the pilot arc electric current.

At this moment, because the 3rd gate signal S3 to the six gate signal S6 are not imported into the 4th IGCT element SR4 to the six IGCT element SR6 of the pure bridge commutating circuit of three-phase PB downside support arm, so these IGCT elements become closed condition.Therefore, voltage between section CP and the machined object CW becomes with the voltage after partial voltage (for example 60V is following) that will constitute between first resistor R 1 of guiding supply circuit and the electrode EL that second resistor R 2 will be applied to pilot arc generative circuit PG and cutter shown in Fig. 2 (M).

Constantly during t=t2, the gas signal Ar shown in Fig. 2 (K) is output and when supplying with plasma gas, electrode EL breaks away from section CP.Because this breaks away from, by flowing through the pilot arc electric current generation electric arc between section CP and the electrode EL, this electric arc sprays with plasma gas from the hole of section CP front end becomes pilot arc.

By the generation of this pilot arc, the shunt current of pilot arc electric current flows through first resistor R 1, shunting supply circuit (circuit that connects first resistor R 1 and output current detection circuit CT), output current detection circuit CT, mother metal terminal MT, machined object CW, electrode EL successively.This shunt current is detected by output current detection circuit CT, when the value of output current detection signal Ct is bigger than predetermined value (with reference to moment t=t3), guiding/main arc commutation circuit SW switches to a side from the b side, and second the phase control signal Pc2 that is imported into guiding/main arc commutation circuit SW from the pure electric bridge of three-phase position phase control circuit PC is imported into the second thyristor driving circuit SD2.

That is, pilot arc is stopped with the rectification action of rectification circuit, replaces, and carries out the rectification action of the pure bridge commutating circuit of three-phase PB.

The second thyristor driving circuit SD2 is according to the input of second phase control signal Pc2, generate the 4th gate signal S4 shown in Fig. 2 (E) and, the 5th gate signal S5 shown in Fig. 2 (F) and, the 6th gate signal S6 shown in Fig. 2 (G), and output to the gate pole of the 4th IGCT element SR4, the 5th IGCT element SR5, the 6th IGCT element SR6 successively respectively.Thus, the 4th IGCT element SR4 to the six IGCT element SR6 of the pure bridge commutating circuit of three-phase PB downside support arm quilt is scratch start successively, the rectification action beginning of the pure bridge commutating circuit of three-phase PB.

Because when pilot arc stops with the rectification of rectification circuit action, do not have supply capability to load with rectification circuit, so pilot arc disappears from pilot arc.On the other hand, owing to replace the pilot arc rectification circuit, the pure bridge commutating circuit of three-phase PB moves, and to load, so produces main arc between the section CP of cutter and the machined object CW from the pure bridge commutating circuit of three-phase PB supply capability.

After the t=t3, the first IGCT element SR1 to the, the six IGCT element SR6 of the pure bridge commutating circuit of three-phase PB are controlled mutually by the position constantly, continue main arc takes place, and utilize the cut-out of the machined object CW of plasma arc to handle.

Like this, among the embodiment 1, pilot arc generative circuit PG is appended on the pure bridge commutating circuit of the three-phase PB, constitute the pilot arc rectification circuit with the first IGCT element SR1 to the, the three IGCT element SR3 of the upside support arm of the pure bridge commutating circuit of three-phase PB and the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG, because when producing pilot arc from this pilot arc rectification circuit supply capability, when producing main arc from the mode of the pure bridge commutating circuit of three-phase PB supply capability, separation is for the dc source of two electric arcs, can use the IGCT element littler to constitute cheapization of energy implement device so constitute the first IGCT element SR1 to the, the six IGCT element SR6 of the pure bridge commutating circuit of three-phase PB than former IGCT element volume.

In addition, in the present embodiment, shown in Figure 9 appended pilot arc generative circuit PG with precedent, but because pilot arc generative circuit PG only flows through the little electric current that is used for pilot arc generation usefulness, so as the 7th IGCT element SR7 to the nine IGCT element SR9 that constitute pilot arc generative circuit PG, can use than the IGCT element that constitutes the pure bridge commutating circuit of the three-phase PB small-sized IGCT element of low capacity more, even append pilot arc generative circuit PG, also can all realize small-sized, cheapization of plasma arc electric power apparatus.

Fig. 3 relates to the electrical connection graph of the plasma arc electric power apparatus of embodiment 2.Because with using the symbolic representation identical among the figure and carrying out same action, so the different place of following explanation with the electrical connection graph of the plasma arc electric power apparatus of embodiment shown in Figure 11.

Among Fig. 3, three-phase mixed electrical bridge rectification circuit MB is with by the 1st diode D1 of the first terminal of the primary side that is connected in three-phase transformer IN be connected in first support arm that the 4th IGCT element SR4 of above-mentioned tie point constitutes, by the 2nd diode D2 of second terminal of the primary side that is connected in three-phase transformer IN be connected in second support arm that the 5th IGCT element SR5 of above-mentioned tie point constitutes, with carry out three phase bridge by the 3rd diode D3 of the 3rd terminal of the primary side that is connected in three-phase transformer IN and the 3rd support arm that the 6th IGCT element SR6 that is connected in above-mentioned tie point constitutes and be connected and form.

Three-phase mixed electrical bridge position phase control circuit PM begins action when input initiating signal Ts.Three-phase mixed electrical bridge position phase control circuit PM the position is controlled mutually the 4th IGCT element SR4 to the six IGCT element SR6 of downside support arm of three-phase mixed electrical bridge rectification circuit MB and pilot arc generative circuit PG the 7th IGCT element SR7 to the nine IGCT element SR9 three-phase mixed electrical bridge position mutually control signal Pm output to guiding/main arc commutation circuit SW.

The second thyristor driving circuit SD2 is according to the three-phase mixed electrical bridge position phase control signal Pm that is transfused to by guiding/main arc commutation circuit SW, generate the 4th gate signal S4, the 5th gate signal S5 and the 6th gate signal S6 of each gate pole of control the 4th IGCT element SR4, the 5th IGCT element SR5 and the 6th IGCT element SR6, they are input to the gate pole of the 4th IGCT element SR4, the 5th IGCT element SR5 and the 6th IGCT element SR6 respectively.

The 3rd thyristor driving circuit SD3 is according to the three-phase mixed electrical bridge position phase control signal Pm that is transfused to by guiding/main arc commutation circuit SW, the 7th gate signal S7, the 8th gate signal S8 and the 9th gate signal S9 of the 7th IGCT element SR7, the 8th IGCT element SR8 of generation control pilot arc generation circuit and each gate pole of the 9th IGCT element SR9, they are input to the gate pole of the 7th IGCT element SR7, the 8th IGCT element SR8 and the 9th IGCT element SR9 respectively.

Fig. 4 is the oscillogram that the action of the plasma arc electric power apparatus that relates to embodiment 2 is described.The waveform of Fig. 4 (A) is represented the waveform of initiating signal Ts, and the waveform of Fig. 4 (B) is represented the waveform of the 4th gate signal S4, and the waveform of Fig. 4 (C) is represented the waveform of the 5th gate signal S5, and the waveform of Fig. 4 (D) is represented the waveform of the 6th gate signal S6.The waveform of Fig. 4 (E) is represented the waveform of the 7th gate signal S7, and the waveform of Fig. 4 (F) is represented the waveform of the 8th gate signal S8, and the waveform of Fig. 4 (G) is represented the waveform of the 9th gate signal S9.In addition, the waveform of Fig. 4 (H) is represented the waveform of gas signal Ar, and the waveform of Fig. 4 (I) is represented the waveform of output current detection signal Ct, and the waveform of Fig. 4 (J) is represented the voltage waveform Vo between electrode EL and the machined object CW.

During moment t=t1, when the initiating signal Ts shown in Fig. 4 (A) is imported into three-phase mixed electrical bridge position phase control circuit PM, three-phase mixed electrical bridge position phase control circuit PM begins action, and three-phase mixed electrical bridge position phase control signal Pm shown in Figure 3 is outputed to guiding/main arc commutation circuit SW.

Constantly during t=t1, because output current does not flow through main supply circuit, so the value of the output current detection signal Ct that is output from output current detection circuit CT is zero.Because the value of output current detection signal Ct is than predetermined value hour, guiding/main arc commutation circuit SW is switched to the b side, so during moment t=t1, the three-phase mixed electrical bridge position phase control signal Pm that is imported into guiding/main arc commutation circuit SW from three-phase mixed electrical bridge position phase control circuit PM is imported into the 3rd thyristor driving circuit SD3.

The 3rd thyristor driving circuit SD3 is according to three-phase mixed electrical bridge position phase control signal Pm, generate the 7th gate signal S7 shown in Fig. 4 (E) of 120 ° of position phase deviations and, the 8th gate signal S8 shown in Fig. 4 (F) and, the 9th gate signal S9 shown in Fig. 4 (G), and output to the gate pole of the 7th IGCT element SR7, the 8th IGCT element SR8, the 9th IGCT element SR9 successively respectively.

By the 7th gate signal S7 to the nine gate signal S9, the 7th IGCT element SR7, the 8th IGCT element SR8 of pilot arc generative circuit PG and the 9th IGCT element SR9 quilt be scratch start successively, and pilot arc electric current (for example about 20A～30A) is fed between section CP and the electrode EL by first resistor R 1 and second resistor R 2 of guiding supply circuit.

At this moment, because the 4th gate signal S4 to the six gate signal S6 are not imported into the 4th IGCT element SR4, the 5th IGCT element SR5 and the 6th IGCT element SR6 of main arc generation usefulness, so these IGCT elements become closed condition.Therefore, voltage between section CP and the machined object CW becomes with the voltage after partial voltage (for example 60V is following) that will constitute between first resistor R 1 of guiding supply circuit and the electrode EL that second resistor R 2 will be applied to pilot arc generative circuit PG and cutter shown in Fig. 4 (J).

Constantly during t=t2, the gas signal Ar shown in Fig. 4 (H) is output and when supplying with plasma gas, electrode EL breaks away from section CP.Because this breaks away from, by flowing through the pilot arc electric current generation electric arc between section CP and the electrode EL, this electric arc sprays with plasma gas from the hole of section CP front end becomes pilot arc.

By the generation of this pilot arc, the shunt current of pilot arc electric current flows through first resistor R 1, shunting supply circuit, output current detection circuit CT, mother metal terminal MT, machined object CW, electrode EL successively.This shunt current is detected by output current detection circuit CT, when the value of output current detection signal Ct is bigger than predetermined value (with reference to moment t=t3), guiding/main arc commutation circuit SW switches to a side from the b side, thus, the three-phase mixed electrical bridge position phase control signal Pm that is imported into guiding/main arc commutation circuit SW from three-phase mixed electrical bridge position phase control circuit PM is imported into the second thyristor driving circuit SD2.

The second thyristor driving circuit SD2 is according to the input of second phase control signal Pc2, generate the 4th gate signal S4 shown in Fig. 4 (B) of 120 ° of position phase deviations and, the 5th gate signal S5 shown in Fig. 4 (C) and, the 6th gate signal S6 shown in Fig. 4 (D), and output to the gate pole of the 4th IGCT element SR4, the 5th IGCT element SR5, the 6th IGCT element SR6 successively respectively.Thus, the 4th IGCT element SR4 to the six IGCT element SR6 of three-phase mixed electrical bridge rectification circuit MB downside support arm quilt is scratch start successively, the rectification action beginning of three-phase mixed electrical bridge rectification circuit MB.

Because when pilot arc stops with the rectification of rectification circuit action, do not have supply capability to load with rectification circuit, so pilot arc disappears from pilot arc.On the other hand, owing to replace the pilot arc rectification circuit, three-phase mixed electrical bridge rectification circuit MB action, electric power is supplied to load from three-phase mixed electrical bridge rectification circuit MB, so produces main arc between the section CP of cutter and the machined object CW.

Like this, in embodiment 2, because separate to the dc source of pilot arc with to the dc source of main arc, so constitute the 4th IGCT element SR4 to the six IGCT element SR6 of three-phase mixed electrical bridge rectification circuit MB, can constitute cheapization of energy implement device with IGCT element than former IGCT element low capacity.

Fig. 5 relates to the electrical connection graph of the plasma arc electric power apparatus of embodiment 3.

The plasma arc electric power apparatus of embodiment 3 is in the plasma arc electric power apparatus of embodiment shown in Figure 11 diode to be appended at the supply unit of shunting on the supply circuit.

Because Fig. 5 uses to represent with the prosign of the electrical connection graph of the plasma arc electric power apparatus of embodiment shown in Figure 11 and carry out same action, so the different place of following explanation.

As shown in Figure 5, the anode of the 4th diode D4 is connected on the tie point of first resistor R 1 and second resistor R 2, and the negative electrode of the 4th diode D4 is connected on the tie point of direct current reactance coil DCL and output current detection circuit CT.The signal road formation that constitutes by the 4th diode D4 will supply to the shunting supply circuit of output current detection circuit CT because of the shunt current that produces of pilot arc.

Fig. 6 is the oscillogram that the action of the plasma arc electric power apparatus that relates to embodiment 3 is described.

The waveform of Fig. 6 (A) is represented the waveform of initiating signal Ts, and the waveform of Fig. 6 (B) is represented the waveform of the first gate signal S1, and the waveform of Fig. 6 (C) is represented the waveform of the second gate signal S2, and the waveform of Fig. 6 (D) is represented the waveform of the 3rd gate signal S3.The waveform of Fig. 6 (E) is represented the waveform of the 4th gate signal S4, and the waveform of Fig. 6 (F) is represented the waveform of the 5th gate signal S5, and the waveform of Fig. 6 (G) is represented the waveform of the 6th gate signal S6.The waveform of Fig. 6 (H) is represented the waveform of the 7th gate signal S7, and the waveform of Fig. 6 (I) is represented the waveform of the 8th gate signal S8, and the waveform of Fig. 6 (J) is represented the waveform of the 9th gate signal S9.In addition, the waveform of Fig. 6 (K) is represented the waveform of gas signal Ar, the waveform of Fig. 6 (L) is represented the waveform of output current detection signal Ct, the waveform of Fig. 6 (M) is represented the voltage waveform Vo between electrode EL and the machined object CW, and the waveform of Fig. 6 (N) represents to be applied to the negative electrode of the 4th diode D4, the voltage waveform Dv between anode terminal.

Among Fig. 6, the action of t=t1～t2 constantly is identical with the situation of Fig. 4, omits explanation.

Among the moment t=t3 shown in Fig. 6 (L), by the generation of this pilot arc, the shunt current of pilot arc electric current flows through first resistor R the 1, the 4th diode D4, output current detection circuit CT, mother metal terminal MT, machined object CW, electrode EL successively.This shunt current is detected by output current detection circuit CT, when the value of this output current detection signal Ct is bigger than predetermined value (with reference to moment t=t3), guiding/main arc commutation circuit SW switches to a side from the b side, and second the phase control signal Pc2 that is imported into guiding/main arc commutation circuit SW from the pure electric bridge of three-phase position phase control circuit PC is imported into the second thyristor driving circuit SD2.

The second thyristor driving circuit SD2 is according to the input of second phase control signal Pc2, generate the 4th gate signal S4 shown in Fig. 6 (E) and, the 5th gate signal S5 shown in Fig. 6 (F) and, the 6th gate signal S6 shown in Fig. 6 (G), and output to the gate pole of the 4th IGCT element SR4, the 5th IGCT element SR5, the 6th IGCT element SR6 successively respectively.Thus, the 4th IGCT element SR4 to the six IGCT element SR6 of the pure bridge commutating circuit of three-phase PB downside support arm quilt is scratch start successively, the rectification action beginning of the pure bridge commutating circuit of three-phase PB.

During moment t=t3 shown in Fig. 6 (L), because the voltage height of the voltage ratio anode-side of the cathode side of the 4th diode D4, so the 4th diode D4 becomes bias state, blocking flows to the electric current of electrode EL from section CP.

Constantly during t=t4, when producing arc cutting in main arc takes place, by direct current reactance coil DCL, (for example about 500V～600V) also is applied between the negative electrode, anode terminal of the 4th diode D4 to produce the crest voltage shown in Fig. 6 (N).But,, be not applied on the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG because this crest voltage is applied on the 4th diode D4 with the reverse blas direction.

That is, the 4th diode D4 plays the protection diode to the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG.

Like this, among the embodiment 3, by the shunting supply circuit between guiding supply circuit and main supply circuit the 4th diode D4 is set, can prevents the destruction of each IGCT element of the pilot arc generative circuit PG that crest voltage caused that takes place because of arc cutting.

Fig. 7 relates to the electrical connection graph of the plasma arc electric power apparatus of embodiment 4.

The plasma arc electric power apparatus that relates to embodiment 4 is the supply unit that in the plasma arc electric power apparatus of embodiment shown in Figure 53 diode is appended between first resistor R 1 and second resistor R 2.

Because Fig. 7 uses to represent with the prosign of the electrical connection graph of the plasma arc electric power apparatus of embodiment shown in Figure 11 and carry out same action, so the different place of following explanation.In addition, the Fig. 6 that uses in the explanation with reference to embodiment 3 illustrates the action of the plasma arc electric power apparatus of embodiment 4.

As shown in Figure 7, first resistor R the 1, the 5th diode D5 and second resistor R 2 are connected in series between pilot arc generative circuit PG and the guide terminal PT and form the guiding supply circuit.With the 4th diode D4 design between the tie point of the tie point of the 5th diode D5 and second resistor R 2 and direct current reactance coil DCL and output current detection circuit CT.

During moment t=t4 shown in Fig. 6 (L), when in main arc takes place, producing arc cutting, by direct current reactance coil DCL, produce the crest voltage (for example about 500V～600V) shown in Fig. 6 (N) and be applied between the negative electrode, anode terminal of the 4th diode D4.But, because the 4th diode D4 plays the effect of protection diode as described above, so crest voltage is not applied on the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG.

Yet, section CP is contacted and when main arc took place, by contacting of cut into slices CP and machined object CW, the 4th diode D4 became short-circuit condition with machined object CW.Under this short-circuit condition, when main arc produced arc cutting and direct current reactance coil DCL generation crest voltage, this crest voltage was applied on the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG through machined object CW, section CP, second resistor R 2, first resistor R 1.

Among this embodiment 4, because between second resistor R 2 and first resistor R 1, be provided with the 5th diode D5, even so when guiding supply circuit side applies crest voltage, also be prevented from and be not applied on the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG by the 5th diode D5.

That is, the 5th diode D5 also plays the protection diode to the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG.

Therefore, even under section CP and machined object CW state of contact, crest voltage takes place, also can prevent destruction because of each IGCT element of the pilot arc generative circuit PG of this crest voltage.

Fig. 8 relates to the electrical connection graph of the plasma arc electric power apparatus of embodiment 5.

The plasma arc electric power apparatus of embodiment 5 is a supply unit of removing second resistor R 2 in the plasma arc electric power apparatus of embodiment shown in Figure 74.

Among the embodiment 5; the 4th diode D4 and the 5th diode D5 had as being used for the corresponding crest voltage that produces because of the arc cutting of main arc protect the function of diode of the 7th IGCT element SR7 to the nine IGCT element SR9 of pilot arc generative circuit PG, can obtain effect similarly to Example 4.

In addition, the present invention is not limited to the various embodiments described above.For example, also can replace the pure bridge commutating circuit of the three-phase PB shown in the electrical connection graph of plasma arc electric power apparatus of the foregoing description 3 to embodiment 5, can the 5th diode D5 is being set on the guiding supply circuit, can on the shunting supply circuit, the 4th diode D4 be set with three-phase mixed electrical bridge rectification circuit MB.

Claims

1. a plasma arc electric power apparatus comprises

For the first IGCT element of the 4th IGCT element and the first terminal of the primary side that is connected to three-phase transformer is connected and first support arm that forms at described connected mid point, the second IGCT element of the 5th IGCT element and second terminal of the primary side that is connected to described three-phase transformer is connected and second support arm that forms at described connected mid point, with the 3rd IGCT element of the 6th IGCT element and the 3rd terminal of the primary side that is connected to described three-phase transformer is connected and the 3rd support arm that forms carries out the pure bridge commutating circuit of three-phase that three phase bridge is formed by connecting at described connected mid point; With

Carry-out bit is controlled first of upside support arm that the first IGCT element to the, the three IGCT elements by the pure bridge commutating circuit of described three-phase constitute mutually and is controlled second the pure electric bridge of three-phase position phase control circuit of controlling sets of signals mutually that sets of signals and position are controlled the downside support arm that the 4th IGCT element to the six IGCT elements by the pure bridge commutating circuit of described three-phase constitute mutually mutually

During the input initiating signal, export first of the pure electric bridge of described three-phase position phase control circuit and control mutually that sets of signals is controlled sets of signals mutually with second and the position is controlled the pure bridge commutating circuit of described three-phase mutually, simultaneously, the section and the electrode of cutter become contact condition, the guiding supply circuit of the pure bridge commutating circuit of described three-phase by constituting by resistor, the little electric current of energising predetermined value between described section and described electrode, then supply with plasma gas, when described electrode and described section disengaging and generation pilot arc, after described pilot arc takes place, the pure bridge commutating circuit of described three-phase is by main supply circuit, main arc also takes place in the big electric current of energising predetermined value, it is characterized in that, also comprise:

By the 7th IGCT element of the mid point that is connected in described first support arm, be connected in described second support arm mid point the 8th IGCT element and be connected in the pilot arc generative circuit that the 9th IGCT element of the mid point of described the 3rd support arm constitutes; With

When described main supply is zero for the output current of circuit; When described first phase control signal group is input to the upside support arm of the pure bridge commutating circuit of described three-phase; Described second phase control signal group is input to described pilot arc generative circuit; When the described main supply of then switching on is given the output current of circuit; The guiding of the downside support arm of the pure bridge commutating circuit of described three-phase/main electric arc commutation circuit is switched and be input to described second phase control signal group from described pilot arc generative circuit

During the input initiating signal, when described first is controlled sets of signals mutually and is input to the upside support arm of the pure bridge commutating circuit of described three-phase, control sets of signals mutually with described second and be input to described pilot arc generative circuit, by described guiding supply circuit, power-on boot arc current between described section and the described electrode, then supply with plasma gas, described electrode and described section break away from the generation pilot arc, detecting the described guiding supply circuit of shunt current process of described pilot arc electric current, the shunting supply circuit, main supply circuit and when machined object flows between electrode, control the downside support arm that sets of signals is input to the pure bridge commutating circuit of described three-phase mutually with described second, by switch on big electric current and main arc takes place of described main supply circuit, pilot arc is disappeared.

2. plasma arc electric power apparatus as claimed in claim 1 is characterized in that,

Replace the first IGCT element to the, the three IGCT elements of the pure bridge commutating circuit of described three-phase and form three-phase mixed electrical bridge rectification circuit with the 1st diode to the 3 diodes, the pure bridge commutating circuit of described three-phase is replaced into described three-phase mixed electrical bridge rectification circuit.

3. plasma arc electric power apparatus as claimed in claim 1 or 2 is characterized in that,

On described shunting supply circuit, be provided with the 4th diode.

4. plasma arc electric power apparatus as claimed in claim 1 or 2 is characterized in that,

On described guiding supply circuit, the 5th diode is set, on described shunting supply circuit, the 4th diode is set.