JP2013172066A - Welding transformer and welding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To save power consumption by precisely controlling welding at high speed.SOLUTION: On a secondary side, one end of one rectifier element 18 is connected to one end of a positive side coil 14, and one end of the other rectifier element 20 is connected to one end of a negative side coil 16. The other end of one rectifier element 18 and the other end of the other rectifier element 20 are connected to a positive electrode 22, and the other end of the positive side coil and the other end of the negative side coil are connected to a negative electrode 24. A pulse-like primary current for inverting a polarity at a constant repetition frequency by an inverter is supplied to a primary coil. The primary coil 12 is sandwiched between the positive side coil 14 and the negative side coil 16. One end of the positive side coil 14 is electrically connected to a positive side conductor 30 via a first coupling electrode plate 44, and one end of the negative side coil 16 is electrically connected to a negative side conductor 32 via a second coupling electrode plate 46. The positive side conductor 30 and the negative side conductor 32 are made in close contact with each other via an insulation layer. Therefore, a commutation time can be reduced, so as to control the inverter at a high frequency.

Description

  The present invention relates to a welding transformer and a welding apparatus for a resistance welder that enable high-speed and high-quality welding.

  A technique is known in which a primary current control by an inverter is performed on a welding transformer for a resistance welder to control a welding current with high accuracy (see Patent Document 1). In addition, attempts have been made to enable higher-speed control by devising the winding structure (see Patent Document 1).

Japanese Patent No. 4687930

High frequency primary current control is required to enable welding with a large current for a short time. In addition to this, in order to perform high-quality welding, it is desired to control at a frequency several times to several tens of times the conventional frequency. However, the conventional welding apparatus has a problem that when the frequency for primary current control is increased several times or more, the intended welding current cannot be obtained or the operation becomes unstable. Further, when the current of the secondary coil increases, there is a possibility that the welding transformer may be damaged due to magnetic saturation.
An object of the present invention is to provide a welding transformer capable of performing precise and high-speed welding control by suppressing high frequency primary current control and magnetic saturation and greatly reducing power consumption, and a welding apparatus using the welding transformer. To do.

The following configurations are means for solving the above-described problems.
<Configuration 1>
A transformer unit in which a primary coil 12, a secondary coil in which a positive coil 14 and a negative coil 16 are connected in series are wound around a magnetic core, and one end of one rectifying element 18 at one end of the positive coil 14 Connecting one end of the other rectifying element 20 to one end of the negative side coil 16, connecting the other end of the one rectifying element 18 and the other end of the other rectifying element 20 to the plus electrode 22, A secondary circuit for connecting the other end of the positive side coil and the other end of the negative side coil to the negative electrode 24, and connecting the positive electrode 22 and the negative electrode 24 to a welding machine 28; Is supplied with a pulsed primary current whose polarity is inverted by an inverter at a constant repetition frequency, and the positive side coil 14 and the negative side coil 16 connect the primary coil 12 between them. It is arranged to sandwich, One end of the positive side coil 14 is electrically connected to the positive side conductor 30 via the first connecting pole plate 44, and one end of the negative side coil 16 is electrically connected to the negative side conductor 32 via the second connecting pole plate 46. The positive-side conductor 30 and the negative-side conductor 32 are disposed so as to be in close contact with each other via an insulating layer 31. The rectifying elements 18 and 20 are disposed on both sides of the positive-side conductor 30 and the negative-side conductor 32. The first electrode plate 34 and the second electrode plate 36 are arranged and sandwiched between the first electrode plate 34 and the second electrode plate 36, and the first electrode plate 34 and the second electrode plate 36 are electrically connected by the third electrode plate 38. And a negative electrode 24 is connected to the other end of the positive side coil and the other end of the negative side coil.

<Configuration 2>
In the welding transformer according to Configuration 1, the positive side coil 14 and the negative side coil 16 are alternately arranged, the primary coil 12 divided and wound between each is arranged, and the divided primary coil 12 is divided. Are all connected in series or all or part are connected in parallel, and the plurality of positive side coils 14 are all connected in parallel or all or part are connected in series, and the plurality of negative side coils 16 are all connected. The plurality of positive side coils 14 and the plurality of negative side coils 16 are connected in series to each other, and one end of each of the plurality of positive side coils 14 is connected to the first side. Connected to the connecting electrode plate 44, one end of the plurality of negative side coils 16 is connected to the second connecting electrode plate 46, and the other end of the plurality of positive side coils 14 and the other end of the plurality of negative side coils 16 are third. Connected to connecting plate 48 Welding transformer, characterized in that the.

<Configuration 3>
The welding transformer according to Configuration 2, wherein the positive side coil 14 and the negative side coil 16 are arranged so as to sandwich the divided primary coil at all locations on the magnetic core.

<Configuration 4>
4. The welding transformer according to claim 1, wherein two one-turn coils obtained by cutting a copper plate into a C shape are connected in series to the secondary coil.

<Configuration 5>
In the welding transformer according to Configuration 1,
A coil unit wound coaxially so that the negative coil 16 is disposed at the center, the primary coil 12 is disposed thereon, and the positive coil 14 is disposed on the outermost periphery, or the positive coil 14 is disposed at the center. A welding transformer in which a primary coil 12 is disposed thereon and a coil unit wound coaxially so as to dispose a negative coil 16 on the outermost periphery is disposed on a magnetic core.

<Configuration 6>
In the welding transformer according to Configuration 1, the first coil is coaxially wound so that the negative coil 16 is disposed at the center, the primary coil 12 is disposed thereon, and the positive coil 14 is disposed on the outermost periphery. A unit and a second coil unit coaxially wound so that a positive coil 14 is disposed at the center, a primary coil 12 is disposed thereon, and a negative coil 16 is disposed on the outermost periphery are arranged on the magnetic core. The welding transformer is characterized in that the magnetic cores are alternately arranged in the axial direction without gaps.
<Configuration 7>
A welding apparatus comprising the welding transformer according to any one of configurations 1 to 6.

<Effect of Configuration 1>
Since the positive side conductor 30 and the negative side conductor 32 are brought into close contact with each other through an insulating layer and the primary coil 12 is sandwiched between the positive side coil 14 and the negative side coil 16, the commutation of the secondary circuit The inductance at the time is reduced, the commutation time is shortened, and the inverter control at a high frequency becomes possible.
<Effect of Configuration 2>
The primary coil, the secondary positive coil, and the negative coil are separately wound to improve the coupling between the primary and secondary coils and prevent magnetic saturation due to a large secondary current.
<Effect of Configuration 3>
The primary coil 12, the positive side coil 14, and the negative side coil 16 can be arranged in close contact with each other evenly at any location.
<Effect of Configuration 4>
Both the positive side coil 14 and the negative side coil 16 through which a large current flows are made simple one-turn coils, the inductance is minimized, and split winding is facilitated.
<Effects of configurations 5 and 6>
Even if the negative side coil 16, the primary coil 12, and the positive side coil 14 are coaxially wound, the same effect as the above configuration can be obtained.

It is a connection diagram of the power supply circuit of the welding apparatus employ | adopted by this invention. FIG. 6 is a connection diagram showing a circuit operation when a forward current flows through the rectifying element 18. 4 is a connection diagram illustrating a circuit operation when a forward current flows through the rectifying element 20. FIG. (A) is a control pulse for controlling the current supplied to the primary side of the transformer, (b) is the primary current, and (c) is the welding current after rectification. It is the disassembled perspective view and side view of an experiment example. It is explanatory drawing which shows the electric current of the secondary circuit in a commutation time. It is a perspective view which shows an example of the primary coil used by this invention, a secondary coil, and a magnetic core. It is the disassembled perspective view and side view which show the principal part Example of the welding transformer of this invention. It is explanatory drawing which shows the positional relationship of a primary coil, a positive side coil, and a negative side coil. It is a perspective view which shows the example of a connection of a secondary coil. It is a disassembled perspective view which shows the Example of the welding transformer of this invention. FIG. 10 is a perspective view of a primary coil 12, a positive side coil 14, and a negative side coil 16 of Example 6.

  Hereinafter, embodiments of the present invention will be described in detail for each example.

FIG. 1 is a connection diagram of a power supply circuit of a welding apparatus employed in the present invention.
A primary current described later with reference to FIG. 4 is supplied to the primary coil 12 of the welding transformer 26. The rectifier circuit employs a single-phase full-wave rectification type. This circuit itself is well known. Although it is not necessary to consider the polarity of the secondary coil itself, for convenience, the secondary coil is referred to as a positive coil 14 and a negative coil 16 connected in series. One end of the rectifying element 18 is connected to one end of the positive side coil 14, one end of the rectifying element 20 is connected to one end of the negative side coil 16, and the other end of the rectifying element 18 and the other end of the rectifying element 20 are combined together as a positive electrode. 22 is connected. The other end of the positive side coil and the other end of the negative side coil are connected via a connection point, and this connection point is connected to the negative electrode 24. A plus electrode 22 and a minus electrode 24 are connected to the welder 28.

FIG. 2 shows a circuit operation when a forward current flows through the rectifying element 18. FIG. 3 shows a circuit operation when a forward current flows through the rectifying element 20.
Equivalent inductance components that cause problems in circuit operation are added to FIGS. That is, the inductance of the positive side conductor 30 connecting the positive side coil 14 and the rectifying element 18, the negative side conductor 32 connecting the negative side coil 16 and the rectifying element 20, and the conductor inside the welding machine 28 are the performance of the welding apparatus. It is thought that it will affect. Details will be described later.

If generation of a large amount of heat generated in the welding transformer 26 and the welding machine 28 can be suppressed, energy saving of the welding apparatus can be achieved. By controlling so as to supply a larger current to the welded portion in a shorter time than before and shortening the welding time, a great power saving effect can be expected.
On the other hand, in order to supply the optimum welding current for the material or structure to be welded, the welding current supply time must be controlled with extremely high accuracy.
For this purpose, an inverter is connected to the primary side of a transformer that supplies a welding current, and the magnitude and supply time of the welding current are controlled by PWM control.

4A shows a control pulse for controlling the current supplied to the primary side of the transformer, FIG. 4B shows the primary current, and FIG. 4C shows the welding current after rectification.
A pulse with a width W controlled by an inverter (not shown) is supplied to the primary coil a fixed number of times within a fixed time H, here a total of 10 times including a positive pulse and a negative pulse. As a result, a current as shown in (b) flows through the primary coil 12 (FIG. 1) of the transformer. Full-wave rectification is performed on the secondary side of the transformer to generate a welding current as shown in (c).

  The welding current can be adjusted by increasing or decreasing the pulse width W shown in FIG. Welding time can be adjusted by increasing / decreasing the number of pulse supply. If the repetition frequency of this pulse is increased, the welding time can be finely adjusted. If the electric power supplied to the primary coil is increased, a larger welding current can be extracted from the secondary coil.

  For example, the conventional welding apparatus supplies a welding current of 200 milliseconds to 700 milliseconds at 10,000 amperes, but the welding current is set to 20,000 amperes, which is twice that of the welding current. In the welding apparatus, the power loss consumed as thermal energy in a place other than the welded portion is extremely large. Therefore, if the welding current is doubled and the welding time is reduced to 1/10, the power consumption can be reduced to 1/5. This enables welding quality equivalent to conventional welding at 10,000 amperes.

  On the other hand, an inverter control pulse for supplying a welding current has conventionally used a repetition frequency of about 1 kHz. However, in order to supply a large current for a short time, a control pulse with higher resolution is required. Desirably, it is desirable to use a pulse having a repetition frequency of about 5 kHz to 50 kHz.

  Thus, it has been found that when a pulse having a repetition frequency several times to several tens of times higher than that of the conventional one is supplied to the primary coil, a welding current having a conventional structure cannot obtain a predetermined welding current. That is, in order to output a large current from the secondary coil by such control, various improvements are required for the structure of the transformer.

  A full-wave rectification type secondary circuit using two rectifying elements 18 and 20 as shown in FIG. 1 has a smaller number of rectifying elements than a circuit using a bridge, can be downsized, and has less power loss. It is known to be suitable for welding equipment.

  However, in this circuit, when the polarity of the voltage induced in the secondary coil is reversed due to the polarity reversal of the current flowing through the primary coil 12, the load current supplied through one rectifying element is transferred to the other rectifying element side. A commutation that changes the flow occurs.

  When the welding current becomes large, the current energy accumulated in the inductance of each part of the circuit becomes very large. The commutation time during which this current energy moves from one rectifying element to the other rectifying element becomes longer as the inductance of each part of the secondary coil shown in FIGS.

  If the commutation of the secondary circuit is not completed during the time M from the start of the fall of the current of the primary coil shown in FIG. 4 to the end of the rise of the current of the opposite polarity, the rise of the secondary current is delayed. As indicated by the dashed line 4, the planned welding current cannot be obtained.

FIG. 5 is an exploded perspective view and a side view of the experimental example.
5 (a) and 5 (b) show an exploded perspective view on the left side and a side view after assembly on the right side. In the example of FIG. 5A, the primary coil 12, the positive coil 14, and the negative coil 16 are wound around a magnetic core (not shown). In order to obtain a hollow structure that takes out a large current and supplies cooling water to the inside, the positive conductor 30 and the negative conductor 32 are made of thick copper plates. The two are separated by a thin insulating layer 31. The rectifying elements 18 and 20 are arranged on both sides of the positive side conductor 30 and the negative side conductor 32 so as to be sandwiched between the first electrode plate 34 and the second electrode plate 36. The first electrode plate 34 and the second electrode plate 36 are electrically connected by a third electrode plate 38, and the plus electrode 22 is fixed to the third electrode plate 38. A copper plate (not shown) is connected to a connection point between the positive side coil 14 and the negative side coil 16 and a minus electrode 24 is attached.

  In the example of FIG. 5B, the primary coil is disposed between the positive side coil 14 and the negative side coil 16. In this structure, the third electrode plate 38 is disposed between the positive conductor 30 and the negative conductor 32, and the rectifying element 18 is sandwiched between the third electrode plate 38 and the positive conductor 30. Further, the rectifying element 20 is sandwiched between the negative conductor 32 and the third electrode plate 38. The positive electrode 22 is fixed to the third electrode plate 38. A copper plate (not shown) is connected to a connection point between the positive side coil 14 and the negative side coil 16 and a minus electrode 24 is attached.

FIG. 6 is an explanatory diagram showing the current of the secondary circuit during the commutation time.
The above experimental example is verified using this figure. FIG. 6 is a three-dimensional representation of the connection between the positive side coil 14 and the negative side coil 16 constituting the secondary coil, and will be described in view of the positional relationship between them. The positive side coil 14 and the negative side coil 16 are wound on a continuous magnetic core (not shown), and the positive side conductor 30 and the negative side conductor 32 are pulled out sideways, and the rectifying element 18 and the rectifying element 20 are drawn. Connected to.

  During the commutation time, a current flows in the direction of C1 through the positive conductor 30, C2 through the positive coil 14, C3 through the negative coil 16, and C4 through the negative conductor 32. In this state, current flows through the positive coil 14 in the direction opposite to C1 until just before, and when commutation is started, current energy accumulated in the positive coil 14 is released in the direction of the negative coil 16. However, it shows. Since no current flows into the positive coil 14 from the direction of the rectifying element 18, the current in the C1 direction disappears when the accumulated energy is released. This completes the commutation.

  In the experimental example of FIG. 5A, the positive side conductor 30 and the negative side conductor 32 having substantially the same shape are brought into close contact with each other through a thin insulating layer 31. With such a structure, as shown in FIG. 6, since the current directions of the positive side conductor 30 and the negative side conductor 32 are opposite to each other, the magnetic fluxes cancel each other and the inductances of both are offset. That is, the inductance of the positive side conductor 30 and the negative side conductor 32 is apparently minimized. Therefore, the commutation time can be further shortened.

  However, when the positive side coil 14 and the negative side coil 16 are disposed in close contact as shown in FIG. 5A, the positive side coil 14 and the negative side coil 16 are placed in the C2 and C3 directions as shown in FIG. It was found that the inductance of these coils greatly affects the flowing current. That is, it has been found that the inductance of the positive side coil 14 and the negative side coil 16 delays the commutation time.

  Further, in the case of the structure of FIG. 5A, the magnetic current between the primary coil 12 and the load current flowing through the positive coil 14 and the load current flowing through the negative coil 16 are magnetic. The degree of coupling is different. In a state where a load current flows through the negative coil 16, the leakage magnetic flux increases. Such imbalance of magnetic coupling is likely to cause an abnormal current.

Furthermore, if a pulse with a high repetition frequency is supplied to the primary coil, the time M from the start of the primary coil current fall to the end of the opposite polarity current is shortened. It is easy to produce. When the positive side coil 14 and the negative side coil 16 are arranged close to each other, magnetic flux due to a large current flowing in the secondary coil concentrates in the vicinity of the secondary coil, and magnetic saturation is likely to occur.

  On the other hand, as shown in FIG. 5B, when a structure in which the primary coil 12 is sandwiched between the positive coil 14 and the negative coil 16 is employed, the positional relationship between the primary coil 12 and the positive coil 14 is primary. The positional relationship between the coil 12 and the negative coil 16 is the same, and no magnetic coupling imbalance occurs. Further, by sandwiching the primary coil 12 between the positive side coil 14 and the negative side coil 16, the distance between the positive side coil 14 and the negative side coil 16 is increased, and the inductance with respect to the current flowing during the commutation time. Can be reduced. In addition, magnetic saturation is less likely to occur than the structure of FIG. However, in the example of FIG. 5B, the distance between the positive conductor 30 and the negative conductor 32 is increased, and the characteristics are worse than those of the example of FIG.

FIG. 7 is a perspective view showing an example of a primary coil, a secondary coil and a magnetic core used in the present invention.
In the present invention, the structure of the transformer portion is improved as follows in consideration of the above experimental example and the like. First, as the primary coil 12, for example, as shown in FIG. 5A, a coil in which a flat insulated wire is wound in multiple layers around a magnetic core is used. As the secondary coil, two one-turn coils obtained by cutting a copper plate into a C shape are connected in series and used. (B) is the positive coil 14 and (c) is the negative coil 16. These are wound around the magnetic core 25 as shown in FIG.

FIG. 8 shows an embodiment of a main part of the welding transformer according to the present invention and is illustrated in the same manner as FIG.
First, in the embodiment of FIG. 8A, the primary coil 12 is sandwiched between the positive coil 14 and the negative coil 16. The primary coil 12, the positive coil 14, and the negative coil 16 are wound around a magnetic core 25 indicated by a wavy line on the right side of 8 (a).

  One end of the positive side coil 14 is electrically connected to the positive side conductor 30 via the first connecting electrode plate 44. One end of the negative side coil 16 is electrically connected to the negative side conductor 32 via the second connecting electrode plate 46. The positive coil 14 and the negative coil 16 are connected in series via an intermediate conductor 40. The intermediate conductor 40 is electrically connected to the lead conductor 42. The coil and the conductor are made of a copper plate in order to obtain a hollow structure that takes out a large current to be supplied to the welding machine and supplies cooling water to the inside. Since the first connection electrode plate 44 and the second connection electrode plate 46 are provided, the positive conductor 30 and the negative conductor 32 can be brought into close contact with each other through the thin insulating layer 31.

  The rectifying elements 18 and 20 are arranged on both sides so as to sandwich the positive conductor 30 and the negative conductor 32, and the outside is sandwiched between the first electrode plate 34 and the second electrode plate 36. The first electrode plate 34 and the second electrode plate 36 are electrically connected by a third electrode plate 38, and the plus electrode 22 is fixed to the third electrode plate 38. The minus electrode 24 (FIG. 6) is attached via the lead conductor 42.

  According to the structure of FIG. 8A, the positive side conductor 30 and the negative side conductor 32 are arranged close to each other, so that the inductance of the positive side conductor 30 and the negative side conductor 32 during commutation time can be minimized. Moreover, since the distance between the positive side coil 14 and the negative side coil 16 was separated, the inductance of the positive side coil 14 and the negative side coil 16 during the commutation time can be reduced. As a result, the commutation time can be shortened, and control using a pulse having a repetition frequency of about 5 kHz to 50 kHz, which is an object of the present invention, can be performed.

  Further, since the primary coil 12 is disposed between the positive side coil 14 and the negative side coil 16, the balance of magnetic coupling between the primary coil 12 and the positive side coil 14 or the negative side coil 16 is good. A stable and good welding current can be obtained. Furthermore, the magnetic saturation of the magnetic core 25 can be made difficult to occur by separating the positive coil 14 and the negative coil 16 through which a large current flows.

  In the example of FIG. 8B, three pairs of the positive side coil 14 and the negative side coil 16 are used. That is, the positive side coil 14 and the negative side coil 16 are alternately arranged, and the primary coil 12 that is divided and wound is arranged between them. The primary coils 12 that are divided and wound may all be connected in series, or all or some of them may be connected in parallel. The plurality of positive side coils 14 may all be connected in parallel, or all or some of them may be connected in series. The plurality of negative coils 16 may all be connected in parallel, or all or some of them may be connected in series. Moreover, you may increase the number of the positive side coils 14 and the negative side coils 16 freely.

  The plurality of positive coils 14 and the plurality of negative coils 16 are connected in series. One end of the positive side coil 14 is electrically connected to the positive side conductor 30 via the first connecting electrode plate 44. One end of the negative side coil 16 is electrically connected to the negative side conductor 32 via the second connecting electrode plate 46. The other end of the positive side coil 14 and the other end of the negative side coil 16 are electrically connected to the third coupling electrode plate 48.

  The rectifying elements 18 and 20 are arranged on both sides so that the positive conductor 30 and the negative conductor 32 are sandwiched, and the outside is sandwiched between the first electrode plate 34 and the second electrode plate 36. The first electrode plate 34 and the second electrode plate 36 are electrically connected by a third electrode plate 38. The positive electrode 22 is fixed to the third electrode plate 38. The third connecting electrode plate 48 is connected to the negative electrode 24.

  In addition, for electrical connection among the plurality of positive side coils 14 and the plurality of negative side coils 16, the first connection electrode plate 44, the second connection electrode plate 46 and the third connection electrode plate 48, A substrate 62 is disposed. The plurality of protrusions provided on the upper surface of the substrate 62 are fixed and electrically connected to the terminals of the positive coil 14 and the negative coil 16. Moreover, these protrusions are cylindrical, and the cooling water may flow into the hollow portions of the positive coil 14 and the negative coil 16 through these protrusions.

  The conductor structure of the substrate 62 can be arbitrarily designed as long as equivalent wiring is possible. In particular, since the substrate 62 is directly connected to the plurality of positive side coils 14 and the plurality of negative side coils 16, the positive side coil 14, the negative side coil 16 and the primary coil can be strengthened by cooling with a hollow structure. Can be cooled.

  As shown in the figure, one end of the plurality of positive side coils 14 is connected to the first connection electrode plate 44, one end of the plurality of negative side coils 16 is connected to the second connection electrode plate 46, and the plurality of positive side coils 14 are connected. The other end and the other ends of the plurality of negative coils 16 are connected to the third connecting plate 48, the first connecting plate 44 and the positive conductor 30 are connected, and the second connecting plate 46 and the negative conductor 32 are connected. And connecting the first connecting electrode plate 44 and the second connecting electrode plate 46 close to each other and arranging the positive side conductor 30 and the negative side conductor 32 close to each other, the same as FIG. An effect can be obtained. Note that an insulating layer made of an insulating film or an insulating paint is sandwiched between the conductors arranged in close proximity.

FIG. 9 is an explanatory diagram showing a positional relationship among the primary coil, the positive coil, and the negative coil.
The apparatus shown in FIG. 8B is the apparatus of the second embodiment. In this device, the primary coil, the positive side coil 14 and the negative side coil 16 are in close contact with each other, and the balance is optimally configured. As shown in FIG. 9A, in order from the top, each of the positive side coil 14, the primary coil 12, the negative side coil 16, the primary coil 12, the positive side coil 14, the primary coil 12,. Coils are arranged.

  It is assumed that the plurality of positive side coils 14 are all connected in parallel and one terminal is connected to the positive side conductor 30. Further, it is assumed that all the negative side coils 16 are connected in parallel and one terminal is connected to the negative side conductor 32. A substrate 62 electrically connects them. FIG. 9B illustrates only a portion where the current flows effectively when the current of the positive side coil 14 is supplied to the welding machine side. FIG. 9C illustrates only a portion where the current flows effectively when the current of the negative side coil 16 is supplied to the welding machine side.

  As can be seen from FIG. 9B, any primary coil 12 is in close contact with any positive coil 14. Further, as can be seen from FIG. 9C, any primary coil 12 is in close contact with any negative coil 16. This is because the positive coil 14 and the negative coil 16 are arranged so as to sandwich the divided primary coil 12 at all locations on the magnetic core.

  Thereby, the magnetic coupling between the primary coil 12 and the positive coil 14 and the magnetic coupling between the primary coil 12 and the negative coil 16 are good, and the positive coil 14 and the negative coil 16 are completely connected. Balanced. 9 corresponds to the embodiment of FIG. 8B, the coil group (12, 14, 16) is seen from the front, and the positive side conductor 30 and the negative side conductor are shown. 32 etc. have shown the state seen from the side.

FIG. 10 is a perspective view showing an example of the connection of the secondary coil, where (a) shows the apparatus of the second embodiment and (b) shows the apparatus of the fifth embodiment.
The apparatus of FIG. 8B described in the second embodiment connects, for example, the positive coil 14 and the negative coil 16 as illustrated. From the front of the figure, three sets of a positive coil 14 and a negative coil 16 are connected in series. One terminal of the positive side coil 14 is connected to the first connection electrode plate 44, and one terminal of the negative side coil 16 is connected to the second connection electrode plate 46. A connection point between the positive side coil 14 and the negative side coil 16 is connected to the third connecting electrode plate 48. All the primary coils 12 (FIG. 8) that have been separately wound are connected in series. However, all or part of them may be connected in parallel. The same applies to the secondary coil. The positive side coil 14 and the negative side coil 16 may be used by connecting them all in parallel, or may be used by connecting all or part of them in series. It can also be switched according to the required output voltage. Moreover, the positive side coil 14 and the negative side coil 16 do not necessarily need to be the same number. Moreover, the thickness and shape of each coil may not necessarily be the same. Of course, the positive side coil 14 and the negative side coil 16 are connected in series with each other.

  The connection distance between each coil and the first connection electrode plate 44 or the second connection electrode plate 46 is short. However, the first connecting electrode plate 44 and the second connecting electrode plate 46, and the positive side conductor 30 and the negative side conductor 32 connected thereto are longer than the coil size. Therefore, the inductance of this part becomes a problem. Therefore, as described above, the positive conductor 30 and the negative conductor 32 are arranged close to each other. Note that the first connection electrode plate 44 and the second connection electrode plate 46 are inevitably disposed in this manner, but the third connection electrode plate 48 is connected to the first connection electrode plate 44 and the second connection electrode plate 46. It is also effective not to place them between them.

  In FIG. 10B, the positive side coil 14 and the negative side coil 16 are arranged so that their axes are parallel to the left and right. That is, four sets of the positive coil 14 and the negative coil 16 are provided in two vertical rows. In the vertical arrangement, the positive side coils 14 and the negative side coils 16 are alternately arranged. This connection is realized by replacing one terminal of the positive side coil 14 and the negative side coil 16 with respect to the first connection electrode plate 44 and the second connection electrode plate 46 for each set.

FIG. 11 is an exploded perspective view showing an actual welding transformer 10 of the fifth embodiment.
Seven sets of the positive side coil 14 and the negative side coil 16 are arranged as described in FIG. The primary coil 12 is sandwiched between the positive side coil 14 and the negative side coil 16. The input terminal 58 of the primary coil 12 is pulled out to the side. All the primary coils 12 that have been separately wound are connected in series.

  After sandwiching the primary coil 12 between the positive coil 14 and the negative coil 16, the magnetic core 25 is mounted. Although the magnetic core 25 is divided into two parts, the magnetic cores 25 are bound and integrated by a binding band 60. Since the primary coil 12, the positive side coil 14, and the negative side coil 16 are arranged so as to cover almost the entire loop-shaped magnetic core 25, the leakage flux is small and good characteristics are obtained. The connection of the positive side coil 14 and the negative side coil 16 shown in FIG.

FIG. 12 is a perspective view of the primary coil 12, the positive coil 14, and the negative coil 16 of the fifth embodiment.
In the above embodiment, the primary coil 12, the positive coil 14, and the negative coil 16 are arranged on the magnetic core 25 with as little gap as possible to eliminate the leakage magnetic flux and optimize the magnetic coupling between the coils. did. On the other hand, in this embodiment, the primary coil 12, the positive side coil 14, and the negative side coil 16 are lap-wound to increase the degree of magnetic coupling between the coils.

  FIG. 12A is a first coil unit that is coaxially wound so that the negative coil 16 is disposed at the center, the primary coil 12 is disposed thereon, and the positive coil 14 is disposed on the outermost periphery. is there. FIG. 12B shows a second coil unit that is coaxially wound so that the positive coil 14 is disposed at the center, the primary coil 12 is disposed thereon, and the negative coil 16 is disposed on the outermost periphery. is there. Both the positive side coil 14 and the negative side coil 16 are one-turn coils having the same width as the primary coil 12. This is to eliminate the leakage magnetic flux and increase the magnetic coupling between the primary coil and the secondary coil. FIGS. 12C and 12D are perspective views.

  As shown in FIG. 12E, the first coil unit shown in FIG. 12A and the second coil unit shown in FIG. 12B are arranged without gaps on the magnetic core. Thereby, the leakage magnetic flux from between the adjacent coils arranged in the axial direction of the magnetic core can be minimized. Further, since the primary coil 12 is arranged between the positive side coil 14 and the negative side coil 16, the magnetic coupling between the positive side coil 14 and the negative side coil 16 can be reduced, and the above-described implementation is performed. The same effect as the example is obtained. In addition, when the imbalance of the characteristics of the positive side coil 14 and the negative side coil 16 is not a problem, the first coil unit or the second coil unit alone is practical.

  When the elements shown in FIGS. 12A and 12B are alternately arranged, when the positive side coil 14 and the negative side coil 16 having different winding diameters are connected in series or connected in parallel, as a whole The inductance of each coil can be leveled. Further, since the positive side coil 14 and the negative side coil 16 are not directly adjacent to each other, the magnetic coupling between the positive side coil 14 and the negative side coil 16 can be reduced. Furthermore, the manufacturing cost of the positive side coil 14 and the negative side coil 16 can be reduced as compared with the welding transformer shown in FIG.

The welding transformer and welding apparatus of the present invention having the above-described configuration have the following effects when viewed electrically and when viewed thermally.
(Electrical effect)
(1) The first connecting electrode plate 44 and the second connecting electrode plate 46 for electrically connecting the positive side coil 14 and the rectifying element 18 are disposed close to each other, and the positive side conductor 30 and the negative side conductor 32 are arranged. By arranging them close to each other, the inductance of the secondary circuit in the commutation time can be minimized and the commutation time can be shortened.
(2) By arranging the primary coil between the positive side coil and the negative side coil of the secondary coil on the magnetic core, the secondary current due to the inductance of the positive side coil and the negative side coil of the secondary coil. The delay of commutation time can be suppressed.
(3) Since the secondary coils through which a large current flows are distributed on the magnetic core, the magnetic flux can be distributed throughout the magnetic core to prevent magnetic saturation.
(4) If primary current control at a higher frequency than before can be performed, a transformer capable of supplying a large current can be miniaturized and cooling efficiency can be increased.

(Thermal effect)
By disposing the secondary coils through which a large current flows on the magnetic core and sandwiching the primary coils therebetween, the heat dissipation of the secondary coils can be improved. A transformer that supplies a large current generates heat in both the primary coil and the secondary coil. Abnormal heat generation will cause problems such as deterioration of the insulator. The secondary coil through which a large current flows generates heat most intensely, but the temperature can be lowered as compared with the primary coil if it is cooled by supplying a cooling water into the hollow structure. Accordingly, the primary coil sandwiched between the secondary coils is also cooled by the cooling water flowing through the secondary coil. With the above structure, the primary coil can be efficiently cooled.

  The welding apparatus of the present invention is not limited to the above embodiment. For example, a copper plate is exemplified for the connection of the secondary circuit, and each part is connected by screws or the like. However, for example, even if the positive coil 14 and the first connecting electrode plate 44 are continuously integrated, Good. Further, the first connecting electrode plate 44 and the positive conductor 30 may be continuously integrated. The first electrode plate 34, the second electrode plate 36, and the third electrode plate 38 may be continuously integrated. The same applies to the negative side. Each electrode plate may be plate-shaped or rod-shaped. It is preferable to provide a through hole for supplying cooling water inside each secondary coil or electrode plate.

DESCRIPTION OF SYMBOLS 10 Welding transformer 12 Primary coil 14 Positive side coil 16 Negative side coil 18 Rectification element 20 Rectification element 22 Positive electrode 24 Negative electrode 25 Magnetic core 26 Welding transformer 28 Welding machine 30 Positive side conductor 31 Insulating layer 32 Negative side conductor 34 First pole Plate 36 Second electrode plate 38 Third electrode plate 40 Intermediate electrode 42 Extraction electrode 44 First connection electrode plate 46 Second connection electrode plate 48 Third connection electrode plate 58 Input terminal 60 Binding band 62 Substrate

Claims (7)

A transformer unit in which a primary coil 12 and a secondary coil in which a positive coil 14 and a negative coil 16 are connected in series are wound around a magnetic core;
One end of one rectifier element 18 is connected to one end of the positive side coil 14, one end of the other rectifier element 20 is connected to one end of the negative side coil 16, and the other end of the one rectifier element 18 and the other end The other end of the rectifying element 20 is connected to the plus electrode 22, the other end of the positive side coil and the other end of the negative side coil are connected to the minus electrode 24, and the plus electrode 22 and the minus electrode 24 are connected to a welding machine. A secondary circuit connected to 28,
The primary coil is supplied with a pulsed primary current whose polarity is inverted by an inverter at a constant repetition frequency,
The positive side coil 14 and the negative side coil 16 are disposed so as to sandwich the primary coil 12 therebetween,
One end of the positive side coil 14 is electrically connected to the positive side conductor 30 via the first connecting pole plate 44, and one end of the negative side coil 16 is electrically connected to the negative side conductor 32 via the second connecting pole plate 46. And
The positive side conductor 30 and the negative side conductor 32 are arranged so as to be in close contact with each other through an insulating layer 31.
The rectifying elements 18 and 20 are arranged on both sides of the positive side conductor 30 and the negative side conductor 32, and are sandwiched between a first electrode plate 34 and a second electrode plate 36, and the first electrode plate 34 and the second electrode plate 36. 36 is electrically connected by a third electrode plate 38, and the positive electrode 22 is connected to the third electrode plate 38;
A welding transformer, wherein a negative electrode 24 is connected to the other end of the positive side coil and the other end of the negative side coil. The welding transformer according to claim 1,
The positive side coil 14 and the negative side coil 16 are alternately arranged, the primary coil 12 divided and wound between them is arranged, and the divided primary coils 12 are all connected in series or All or part of them are connected in parallel,
The plurality of positive side coils 14 are all connected in parallel or all or part of them are connected in series, and the plurality of negative side coils 16 are all connected in parallel or all or part of them are connected in series.
The plurality of positive side coils 14 and the plurality of negative side coils 16 are connected in series with each other, one end of the plurality of positive side coils 14 is connected to a first connecting electrode plate 44, and the plurality of negative side coils 16 are connected. The welding transformer is characterized in that one end thereof is connected to the second connecting electrode plate 46 and the other end of the plurality of positive side coils 14 and the other end of the plurality of negative side coils 16 are connected to the third connecting electrode plate 48. The welding transformer according to claim 2,
A welding transformer, wherein a positive coil 14 and a negative coil 16 are arranged so as to sandwich a divided primary coil at all locations on a magnetic core. The welding transformer according to any one of claims 1 to 3,
A welding transformer characterized by using two one-turn coils obtained by cutting a copper plate in a C-shape in series connection as a secondary coil. The welding transformer according to claim 1,
A coil unit wound coaxially so that the negative coil 16 is disposed at the center, the primary coil 12 is disposed thereon, and the positive coil 14 is disposed on the outermost periphery, or the positive coil 14 is disposed at the center. A welding transformer in which a primary coil 12 is disposed thereon and a coil unit wound coaxially so as to dispose a negative coil 16 on the outermost periphery is disposed on a magnetic core. The welding transformer according to claim 5,
A negative coil 16 is disposed at the center, a primary coil 12 is disposed thereon, a first coil unit coaxially wound so as to dispose the positive coil 14 on the outermost periphery, and the positive coil 14 is disposed at the center. , The primary coil 12 is disposed thereon, and the second coil unit coaxially wound so as to dispose the negative coil 16 on the outermost periphery is alternately spaced in the axial direction of the magnetic core on the magnetic core. Welding transformer characterized by having been arranged without any.   The welding apparatus provided with the welding transformer in any one of Claims 1 thru | or 6.

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