JP2907746B2 - Power supply - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device, for example, an arc welding machine, a plasma arc cutting machine, a charger, and a power supply device for precious metal plating.

[0002]

2. Description of the Related Art Conventionally, as a power supply device as described above,
A commercial AC power supply is rectified by a rectifier, and the switching transistor supplied with this rectified output is switched at a high frequency, converted into high-frequency power, transformed using a high-frequency transformer, rectified again by the rectifier, and then output. Is used. Since such a power supply device does not require a large transformer or a large choke, there is an advantage that the entire device, in particular, a main circuit including a switching transistor, a high-frequency transformer, and the like can be reduced in size.

In order to further reduce the weight of such a power supply device, the applicant of the present application has adopted a plastic case as a case of these power supply devices in Japanese Patent Application Laid-Open No. Hei 5-283870 and Japanese Patent Application No. Hei 6-300363. A power supply is proposed.

[0004]

However, as the size of such a power supply device is reduced, a main circuit such as a switching circuit such as a switching transistor or a high-frequency transformer and a control circuit for controlling the switching circuit become closer. Will do. Therefore, there is a problem that the control circuit is likely to malfunction due to a high-frequency signal generated by the switching operation of the switching circuit.

Further, since the case is made of plastic which is an insulator, the case cannot be used as ground. Therefore, a ground wire is laid in the case. In addition, there is a problem in that the values of the parasitic capacitance and the parasitic inductance change, which causes the ground point to move, becomes susceptible to noise, and may cause a malfunction. When such a power supply device is used as a power supply for a TIG arc welding machine, there is a gap between the welding work and the torch at the time of startup, and a high-voltage high-frequency signal is applied to perform a discharge between the gaps. I do. This high-frequency signal has a problem that it causes noise to other equipment and causes damage or malfunction of other equipment.

An object of the present invention is to provide a good shield between a switching circuit and its control circuit even when an insulating case is used. Another object of the present invention is to secure a constant ground point even when an insulating case is used. Another object of the present invention is to prevent leakage of a high-frequency signal to the outside even when an insulating case is used.

[0007]

According to a first aspect of the present invention, there is provided an insulative envelope, and a main circuit provided in the envelope and including switching means for switching DC power.
Control means provided in the envelope and controlling the switching means, and shield means provided between the switching means and the control means and connectable to a ground potential point, Is what you do. In addition, the book
In the first invention, the shield means is a plate-like body, and is fixed in the envelope.

[0008] In the first aspect of the present invention, the main circuit further includes DC conversion means for converting the AC power generated by the switching means into DC and supplying the DC power between two output terminals, and the two output terminals. One is connectable to a grounded base material, the other output terminal is connectable to a torch, and the main circuit is a high-frequency signal between the torch and the base material from the other output terminal. And a high-frequency signal bypass capacitor is provided between the shielding means and the high-frequency signal generating means. According to a second aspect of the present invention, in the first aspect, a bypass capacitor is provided between the one output terminal and the shield means.

[0009] The third invention is directed to the first or second invention.
The Oite, and control means for controlling the operation of the high-frequency signal generating means, and the biasing signal generating means for supplying a biasing signal via pair transmission line to the control unit, a transmission line of said pair And a capacitor provided between the shield means.

[0010] The fourth invention is directed to the first or second invention.
Oite, wherein a control means for controlling the operation of the high-frequency signal generating means, and the biasing signal generating means for supplying a biasing signal via pair transmission line to the control means, respectively to the transmission line of said pair And a capacitor provided between one end of the high-frequency signal blocking means and the shield means. Book 5
According to a fourth aspect of the present invention, in the fourth aspect, a capacitor is provided between the other end of the high frequency signal blocking means and the shielding means.

According to a sixth aspect of the present invention, there is provided an insulating envelope, a first output terminal provided in the envelope and connectable to a base material, and a torch provided in the envelope. A second output terminal connectable to the power supply; DC power supply means provided in the envelope for supplying DC power to the first and second output terminals via a pair of transmission paths; High-frequency signal generating means interposed in the torch side of the path, reference potential means connectable to a ground potential point and fixed in an envelope, the high-frequency generating means and the reference potential means, And a bypass capacitor provided between them.

In a seventh aspect based on the sixth aspect , the control means for the high-frequency signal generating means and a switch connected to the control means via a pair of transmission lines so as to operate the control means. And low-pass filter means including a capacitor having one end connected to each of the transmission lines and the other end connected to the reference potential means.

The eighth invention is directed to the sixth or seventh invention.
In the above, the DC power supply means, AC conversion means for converting DC power into AC power by switching, and a control means for AC conversion means provided close to the AC conversion means,
And wherein the reference potential means is a plate-like body provided between the AC conversion means and a control means of the AC conversion means.

[0014]

According to the first aspect, the shield means connectable to the ground potential point is provided between the switching means in the insulating envelope and the control means for controlling the switching means. By connecting the shield means to the ground potential point, the high frequency signal generated by the switching means does not reach the control means side. In addition, since the shield means is a plate-like body and is fixed, it can be used as ground, and the ground point does not move.

Further, the main circuit has a DC converting means and a high-frequency signal generating means, and the high-frequency signal generating means discharges between the torch and the base material. It flows from the material to the reference potential point. Further, the high-frequency signal leaked from the high-frequency signal generating means is bypassed to the shield means, which is an immovable ground point, via the bypass capacitor. According to the second aspect of the invention , in addition to the bypass, even if a high-frequency signal from another device is guided to one output terminal side, the high-frequency signal is bypassed to the shield means via another bypass capacitor.

According to the third aspect, the control means for controlling the operation of the high-frequency signal generating means operates the high-frequency signal generating means in response to a signal from the energizing signal generating means. Even if a high-frequency signal from another device is superimposed on a pair of transmission lines between the control unit and the control unit, the high-frequency signal is bypassed to the shield unit by a capacitor between the transmission line and the shield unit.

According to the fourth invention, the same as the third invention
In addition, high frequency signals from other devices are bypassed by capacitors, but since the high frequency signal blocking means is provided in the transmission line, the high frequency signals from other devices can more reliably arrive at the control means. Can be blocked.
According to the fifth aspect , since the capacitors connected to the shield means are provided at both ends of the high-frequency blocking means, the high-frequency blocking means and the two capacitors cooperate to control the high-frequency signal more firmly. You can prevent them from coming to the means.

According to the sixth aspect, the insulating envelope is provided with DC power supply means for supplying DC power between the torch and the base material. A high-frequency signal generating means for initiating a discharge between them is also provided in the insulating envelope. The high frequency signal generated by the high frequency signal generating means flows from the torch and the base material to the ground potential point. Further, if the reference potential means is connected to the ground potential point, the reference potential means is fixed in the envelope, so that the parasitic capacitance and the parasitic inductance do not change and the ground point moves. There is no. The high-frequency signal is bypassed to the reference potential point by the capacitor provided between the reference potential point and the high-frequency signal generation means.

According to the seventh aspect , the switch means is connected to the control means via the pair of transmission paths so as to operate the control means of the high-frequency signal generation means. May be superimposed.
However, since one end is connected to each of the transmission lines and the other end is provided with low-pass filter means including a capacitor connected to the reference potential means, it is possible to prevent such a high-frequency signal from reaching the control means. Can be.

According to the present invention, the DC power supply means comprises:
AC conversion means for converting DC power into AC power by switching, and control means for the AC conversion means provided close to the AC conversion means, wherein the reference potential means,
Since it is a plate-shaped body provided between the AC conversion means and the control means of the AC conversion means, it is possible to prevent the arrival of the high-frequency signal as described above and the emission of the high-frequency signal to the outside. In addition, since the reference potential means also performs the shielding function, the high-frequency signal radiated from the AC conversion means does not reach the control means of the AC conversion means and does not malfunction.

[0021]

In this embodiment, the present invention is applied to a DC power supply of a DC TIG welding machine, for example, and has input terminals 2 and 4 of a commercial AC power supply as shown in FIG. The commercial AC power supplied to these input terminals 2 and 4 is rectified by an input-side rectifier circuit 6 and then smoothed by a smoothing capacitor 8 to be converted to DC.

The DC power is converted into high-frequency AC power by a switching means, for example, an inverter 10 including a power switching transistor such as an IGBT. This AC power is supplied to the primary side of the high-frequency transformer 12, and a predetermined voltage is generated on the secondary side.

The high-frequency voltage generated on the secondary side of the high-frequency transformer 12 is rectified by an output-side rectifier circuit 14,
It is converted to DC again. The re-DC power is supplied to positive and negative output terminals 16 and 18 via transmission lines 19 and 21.

The input side rectifier circuit 6 and the inverter 1
0, a high-frequency transformer 14 and the like constitute a main circuit. By increasing the output frequency of the inverter 10, the high-frequency transformer 14 can be downsized, and the power supply device can be downsized.

The positive output terminal 16 is connected to a base material, for example, a welding work 20 via a cable 22, and the work 20 is connected to a ground potential point. The negative output terminal 18 is connected to the torch 24 via a cable 26.

Although not shown, an inert gas is supplied to the torch 24 so that an inert gas can be injected from the torch 24 toward the work 20 for performing TIG welding.

Since there is a gap between the torch 24 and the work 20, at the start of welding, a high voltage is applied between the torch 24 and the work 20 in order to generate a discharge, that is, an arc between the gaps. It is necessary to apply a high frequency signal of a voltage. Therefore, a high-frequency signal generation unit, for example, a high-frequency generator 28 is provided on the transmission line 21 between the negative output terminal 18 and the output-side rectifier circuit 14. The high frequency generator 28 starts operating in response to a start signal from the sequence circuit 30. Although not shown, the sequence circuit 30 also supplies and stops the supply of the inert gas by controlling the opening and closing of a valve 76 described later.

During the welding, a portion of the transmission line 21 closer to the output side rectifier circuit 14 than the high frequency generator 28 is constituted by, for example, a current transformer in order to control the load current at a constant current. Current detector 31 is provided. The current detector 31 detects a load current, and this detection signal is fed back to a control device 32 that drives and controls the inverter 10. by this,
The control device 32 controls the inverter 10 to make the load current a constant current. The control device 32 also controls the sequence circuit 30.

That is, the control device 32 is connected to the torch switch connection terminals 34 and 36 via the transmission lines 35 and 37, and these torch switch connection terminals 34 and 36
The torch 24 is connected to a torch switch 38 provided on the torch 24 via cables 40 and 42. These cables 40 and 42 are laid in parallel with the cables 22 and 26 connected to the positive and negative output terminals 16 and 18.

When the torch switch 38 is closed, an energizing signal is supplied to the control device 32. The control device 32 activates the sequence circuit 30, and the sequence circuit 30 starts supplying the inert gas. The high frequency generator 28 is started. Thus, the control device 32 and the sequence circuit 30 function as control means for the high frequency generator 28, and the torch switch 38 functions as an energizing signal generation means. When an arc is generated, the sequence circuit 30 stops the high frequency generator 28.

Such a power supply device is housed in an envelope, for example, a case 44 as shown in FIG. The case 44 has a front panel 4 made of insulating material such as synthetic resin.
6. A rear panel 48 is arranged at a distance from the front panel 46 in the left-right direction shown in FIG. This rear panel 48 is also made of synthetic resin. Also,
A chassis 50 made of a synthetic resin is mounted substantially at the center between the front panel 46 and the rear panel 48 in the vertical direction.

The chassis 50 has a substantially rectangular planar shape, and engaging claws 52 are provided at its four corners. The engaging claws 52 engage the front panel 46 and the rear panel 48, respectively. doing. Front panel 46,
Since the rear panel 48 and the chassis 50 form a substantially H-shape, compression from any direction,
It has a structure that is not easily deformed by pulling, bending and other forces.

Further, a front panel 46 and a rear panel 48
And two side plates 54 formed in the same shape so as to cover the upper portion, the lower portion, and both side portions.

Due to the chassis 50, the inside of the case 44
It is partitioned into two upper and lower regions 56 and 58. The high-frequency transformer 12 is mounted on the lower surface of the chassis 50 at a position near the front panel 46 in the lower area 58.

A recess 60 is provided in the chassis 50 at a position closer to the rear panel 48 than the mounting position of the high frequency transformer 12, and a through hole 62 is formed in the bottom of the recess 60. Radiation fins 64 are attached to the lower surface of the chassis 50 so as to correspond to the through holes 62. The power semiconductor module 66 is mounted on the radiating fin 64 so as to be located in the upper region 56 through the through hole 62. The semiconductor module 66 is formed in a substantially rectangular parallelepiped shape, and includes semiconductor elements constituting the inverter 10, the input-side rectification circuit 6, the output-side rectification circuit 14, and the drive circuit of the inverter 10 in the control device 30, respectively. Have been.

Below the radiating fins 64, a high-frequency generator 28 is disposed.
4 is supported by a mounting portion 67 provided on the mounting member 4. As described above, most of the main circuits such as the high-frequency transformer 12, the high-frequency generator 28, and the radiation fins 64 are accommodated in the lower region 58 of the chassis 50.

On the lower surface side of the chassis 50 closest to the rear panel 48, the high-frequency transformer 12, the radiation fins 6
4. A fan 68 for cooling the high frequency generator 28 is provided. The fan 68 is configured to discharge the air in the area 58 to the rear panel 48 side. Numerous exhaust holes 70 are formed in a region of the rear panel 48 below the chassis 50, through which air sent out by the fan 68 is exhausted to the outside of the case 44. Similarly, a number of air supply holes 72 are formed in a region of the front panel 46 below the chassis 50, and are fed into a new region 58 from these air supply holes 72.

Although the semiconductor module 56 itself is located on the area 56 side, the heat radiation fin 64 to which the semiconductor module 66 is coupled is located in the lower area 64, so that heat generated by the semiconductor module 66 is transmitted to the heat radiation fin 64 side. The heat is radiated from this, and is hardly transmitted to the upper region 56.

Below the exhaust hole 70 of the rear panel 48, a gas inflow portion 7 for introducing an inert gas from the outside is provided.
4 is provided, which is controlled via a valve 76 and a pipe 78 that are opened and closed by the sequence circuit 30.
It is connected to a gas outlet 80 provided on the front panel 46. The gas outlet 80 is disposed below the air supply hole 72, and is connected to the torch 24 via a hose (not shown). This inert gas is injected from the torch 24. In addition, although not shown, positive and negative output terminals 18, 18 and torch connection terminals 34, 36 are also provided on the front panel 46.

In the upper region 56 of the case 44, a printed circuit board 82 on which the control device 32, the sequence circuit 30, and the like are arranged is disposed substantially horizontally. This printed circuit board 8
2 are support members 82, 8 projecting from the upper surface of the chassis 50.
4 supported. The printed circuit board 8
The terminal 86 of the semiconductor module 66 is connected to 2. These terminals 86 are provided on one edge side of the semiconductor module 66 along a straight line connecting the front panel 46 and the rear panel 38.

As is clear from FIG. 1, the semiconductor module 66 and the printed circuit board 82 are arranged very close to each other, and the high-frequency signal generated by the semiconductor module 66 is transmitted to the control device 32 on the printed circuit board 82 side. May be leaked.

In order to prevent this, the printed circuit board 82
A rectangular conductor plate 88 is disposed between the semiconductor module 66 and the semiconductor module 66 so as to substantially cover the upper surface of the semiconductor module 66 and not to contact the terminal 86. This conductor plate 88
Is made of, for example, copper or iron, and is attached to a printed circuit board 82 by a support 90. Further, as shown in FIG. 2, the conductor plate 88 can be connected to a ground potential point via a ground terminal 92. Although not shown, the ground terminal 92 is provided on, for example, the rear panel 48. Of course, the conductor plate 88 and the ground terminal 93 are connected at the shortest distance.

By connecting the ground terminal 92 to the ground potential point, the conductor plate 88 also has the ground potential, and exhibits a shielding effect of preventing a high-frequency signal from the semiconductor module 66 from leaking to the printed circuit board 82 side. That is, the conductor plate 88 functions as a shield means.

The conductor plate 88 has a larger area than a conductor generally used as an earth line or the like, and
In addition to being connected to the ground potential point via 2 and attached to the printed circuit board 82, it does not move.
Therefore, for example, compared to a case where a conductor serving as an earth line connected to the ground terminal 88 is routed inside the insulating case 44, the values of the parasitic capacitance and the parasitic inductance are small and the change is small, and the shift of the earth point is reduced. There is no. That is, the ground point is fixed.

As shown in FIG. 2, a bypass capacitor 94 having one end connected between the current detector 31 and the high frequency generator 28 and one end connected to the transmission line 19 are connected to the conductor plate 68 as shown in FIG. The interconnection point with the bypass capacitor 96 is connected. That is, a bypass path is formed between the connection point between the current detector 31 and the high-frequency generator 28 and the conductor plate 88 by the capacitor 94, and the transmission path 1
A bypass is formed between the capacitor 9 and the conductor plate 88 by the capacitor 96.

The high frequency signal from the high frequency generator 28 is supplied to the negative output terminal 18, cable 26, torch 24, work 2.
The high-frequency signal leaked from the high-frequency generator 28 at the same time as flowing to the ground potential point through 0 is bypassed via the capacitor 94 to the conductor plate 88 as an immovable earth point. Therefore, the high-frequency signal from the high-frequency generator 28 does not interfere with other devices.

Further, since the condenser 96 is provided between the transmission line 19 and the conductor plate 88, when a plurality of TIG welding machines using such a power supply device are used at the same time,
Even if a high-frequency signal from another welding machine is superimposed on the transmission line 19 via the cable 22 and the positive output terminal 16, the high-frequency signal can be bypassed to the conductor plate 88 via the capacitor 96.

Further, high-frequency blocking means, for example, reactors 98 and 100 are provided in the transmission lines 35 and 37 between the control device 32 and the torch switch connection terminals 34 and 36, respectively. The interconnection point of the connected bypass capacitors 102 and 104 is connected to the conductor plate 88.

Similarly, the other ends of the reactors 98 and 100 are connected to the bypass capacitors 106 and 10 having one ends connected thereto.
8 are connected to the conductor plate 88. The reactor 98 and the capacitors 102 and 106 form a low-pass filter.
0 and the capacitors 104 and 108 constitute a low-pass filter.

As described above, the cables 22 and 24 for supplying a load current to the torch 24 and the cables 40 and 42 connected to the torch switch 38 are wired in parallel. As described above, a plurality of such welding machines may be used at the same time. In such a case, a high-frequency signal from its own high-frequency generator 28 or a high-frequency signal from a high-frequency generator 28 of another welding machine may be superimposed on the cable 40 or 42. Cables 40 and 4
Which of the two is superimposed with the high-frequency signal differs from time to time. The high-frequency signal superimposed on any one of such cables is bypassed to the conductor plate 88, and the transmission path 3
In order not to reach the side of 5, 37, the capacitor 106,
108 are provided. The capacitors 94 and 96
, The capacitors 102 and 104, and the capacitors 106 and 108 are desirably connected to the same place on the conductor plate 88. In this case, the ground becomes a single point, and the ground impedance can be reduced as compared with the case where the connection points are dispersed, so that the high-frequency signal can be satisfactorily bypassed.

In the above embodiment, the capacitor 96 is provided to bypass the high-frequency signal superimposed on the transmission line 19, but is unnecessary in some cases. Similarly, the capacitors 102 and 104 and the capacitors 106 and 108 are provided. However, when high-frequency signals are not easily superimposed on the cables 40 and 42, the capacitors 102 and 104 may be removed or the transmission lines 35 and 37 may be removed. If it is difficult for the high frequency signal to be superimposed, the capacitors 106 and 108 may be removed. Further, in order to constitute a low-pass filter, the reactor 9
Although 8, 100 are provided, they may be removed in some cases.

In the above embodiment, the present invention is applied to a power supply device for a TIG welding machine. However, the present invention is not limited to this. For example, a power supply for arc equipment including a plasma arc cutting machine, a charger, The present invention can be applied to a power supply device for precious metal plating. For example, while the configuration of the above embodiment can be used as a charger or the like, if it is used as a dedicated device such as a charger, the high-frequency generator 28 and related devices need to be provided. Absent.

[0053]

According to the first aspect of the present invention, the shield means which can be connected to the ground potential point between the switching means and the control means despite the use of the insulating envelope. since provided, by connecting the shielding means to the ground potential point, can be prevented from leaking to the control unit side of the high-frequency signal switching means is generated, Ru can be prevented that the malfunction of the control means.

Further, according to the first aspect of the present invention, since the shield means is a plate-like body, it has a large area as compared with a ground wire or the like, so that the occurrence of parasitic inductance and the like is small, and it is fixed. Therefore, the shield means itself does not move, and the parasitic inductance and the like hardly change. Therefore, an immovable earth point can be secured.

Further, according to the first aspect of the present invention, when a high frequency signal is applied between the torch and the base material by the high frequency signal generating means, the high frequency signal may leak from the high frequency signal generating means. However, since the leakage high-frequency signal is bypassed by the bypass capacitor with respect to the shield means, which is an immovable ground point, it is possible to prevent the control means and the switching means from malfunctioning or being damaged. According to the second aspect of the present invention, even if a leakage high-frequency signal is induced from the outside at the other output terminal, the signal is bypassed by the bypass capacitor provided between the other output terminal and the shield means. And switching means can be prevented from malfunctioning or being damaged.

According to the third aspect of the present invention, even if the high frequency signal is superimposed on the transmission line for supplying the energizing signal from the energizing signal generating means to the control means for controlling the start of the operation of the high frequency signal generating means. Since the bypass is performed by the capacitor provided between the transmission path and the shield means, it is possible to prevent the control means and the switching means from malfunctioning or being damaged. According to the fourth aspect of the present invention, since the capacitor and the high frequency blocking means constitute a low-pass filter, the control means and the switching means are more reliably prevented from malfunctioning or being damaged. can do. According to the fifth aspect of the present invention, since the high-frequency signal blocking means is further loaded with a capacitor, the control means and the switching means can be more reliably prevented from malfunctioning or being damaged.

According to the sixth aspect of the present invention, the reference potential means connectable to the reference potential point is provided in the insulating envelope even though the insulating envelope is used. Because of the limitation, a bypass capacitor is provided between the reference potential point that does not move and the high-frequency signal blocking unit, so that the leaked high-frequency signal from the high-frequency signal generation unit can be reliably bypassed. It does not interfere with other devices.

According to the present invention, the capacitor of the low-pass filter provided on the pair of transmission paths between the switch means and the control means of the high-frequency signal generating means is moved as described above. Since it is connected to the reference potential means, even if a high frequency signal is superimposed on the transmission line, it can be bypassed. Therefore, the control means of the high-frequency signal generating means does not malfunction.

According to the eighth aspect of the invention, the reference potential means is provided between the AC conversion means included in the DC conversion means and the control means of the AC conversion means disposed close to the DC conversion means. Therefore, the reference potential means also functions as a shield means, and it is possible to prevent a high-frequency signal generated by the AC conversion means from leaking to the control means, and to prevent malfunction or damage of the control means. .

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of one embodiment of a power supply device according to the present invention.

FIG. 2 is a block diagram of the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Inverter (switching means) 14 Output side rectifier circuit (DC conversion means) 16 Positive output terminal 18 Negative output terminal 20 Work (base material) 24 Torch 26 High frequency generator (High frequency signal generator) 30 Sequence circuit (High frequency signal) Control means for generating means) 32 Control device (control means) 35 37 Transmission line 40 Torch switch (energizing signal generating means) 88 Conductor plate (shield means, reference potential means) 94 Bypass capacitor 96 Bypass capacitor 98 100 Reactor ( High frequency signal blocking means) 102 104 106 108 Bypass capacitor

Continuation of the front page (72) Inventor Atsushi Kinoshita 2-14-3 Awaji, Higashiyodogawa-ku, Osaka-shi, Osaka Inside Sansha Electric Manufacturing Co., Ltd. (72) Inventor Takashi Hashimoto 2--14-3, Awaji, Higashiyodogawa-ku, Osaka-shi, Osaka (56) References JP-A-5-283870 (JP, A) JP-A-2-164100 (JP, A) JP-A 63-198389 (JP, U) JP 1 −67798 (JP, U) JP-A 1-61892 (JP, U) JP-A 53-17253 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H02M 1/00- 11/00 B23K 9/00-9/32 H05K 5/00

Claims (8)

(57) [Claims] 1. An insulative envelope, a main circuit provided in the envelope and including switching means for switching DC power, and provided in the envelope;
Control means for controlling the switching means, and shield means provided between the switching means and the control means, the shield means being a plate-like body connectable to a ground potential point and fixed to the envelope. The main circuit has a DC converting means for converting the AC power generated by the switching means into DC and supplying the DC power between two output terminals, and one of the two output terminals is grounded. The other output terminal is connectable to a torch, and the main circuit generates a high-frequency signal for applying a high-frequency signal between the torch and the base material from the other output terminal. A power supply device comprising: means for providing a bypass capacitor between the shielding means and the high-frequency signal generating means. 2. The power supply device according to claim 1, wherein a bypass capacitor is provided between said one output terminal and said shield means. 3. The power supply device according to claim 1, wherein said control means controls the start and stop of said high-frequency signal generation means, and said control means is supplied with an energizing signal via a pair of transmission lines. A power supply device comprising: an energizing signal generating unit; and capacitors provided between the pair of transmission paths and the shielding unit. 4. The power supply device according to claim 1, wherein said control means controls the operation of said high-frequency signal generating means, and said control means supplies an energizing signal to said control means via a pair of transmission lines. A power supply device comprising: signal generating means; high-frequency signal blocking means interposed in the pair of transmission paths; and a capacitor provided between one end of the high-frequency signal blocking means and the shield means. . 5. The power supply device according to claim 4, further comprising a capacitor provided between the other end of said high-frequency signal blocking means and said shielding means. 6. An insulative envelope, a first output terminal provided on the envelope and connectable to a base material, and a first output terminal provided on the envelope and connectable to a torch. 2 output terminals, DC power supply means provided in the envelope, for supplying DC power to the first and second output terminals via a pair of transmission lines, and High-frequency signal generating means interposed between the high-frequency signal generating means, a reference potential means connectable to a ground potential point and fixed in the envelope, and provided between the high-frequency generating means and the reference potential means. A power supply device comprising: a bypass capacitor. 7. The power supply device according to claim 6, wherein said control means controls said high-frequency signal generating means, and said switch means is connected to said control means via a pair of transmission lines so as to operate said control means. And a low-pass filter including a capacitor having one end connected to each of the transmission paths and the other end connected to the reference potential means. 8. The power supply device according to claim 6, wherein said DC power supply means includes AC conversion means for converting DC power into AC power by switching, and AC conversion means provided close to said AC conversion means. A power supply device, comprising: a control unit of a power supply unit, wherein the reference potential unit is a plate-shaped body provided between the AC conversion unit and the control unit of the AC conversion unit.