JPH0331497Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a welding power supply device, and in particular, the invention drives an alternating current generator with an engine, rectifies the generated output, and generates electric power for arc welding. This invention relates to an improvement of a welding power supply device used in a so-called engine welder.

[Conventional technology]

FIG. 6 is an electric circuit diagram of a conventional engine welder, and FIG. 7 is a diagram showing voltage-current characteristics of the engine welder shown in FIG. 6.

In FIG. 6, a self-excited alternator 1 includes a three-phase armature coil 2 and a field coil 3, and is rotationally driven by an engine (not shown). The three-phase armature coils 2 are each connected to a rectifier 5 via a reactor 4 and to an automatic voltage regulator (AVR) 6. The rectifier 5 rectifies the alternating current generated voltage generated in the armature coil 2 which is applied via the reactor 4 and applies it to the terminals 8 and 9.
A welding probe 10 to which a welding rod 11 is attached is connected to the terminal 8, and the terminal 9 is connected to the part 12 to be welded.

The AVR 6 rectifies the three-phase AC power generation output and provides the rectified output to the field coil 3. In addition, AVR
A current regulator 7 is provided in conjunction with 6, and by adjusting this current rectifier 7, the field current flowing through the field coil 3 can be adjusted.

In the engine welder shown in FIG. 6 above, when the engine is rotated at the rated speed, the field coil 3 rotates, and the residual magnetism of the field coil 3 causes a voltage of about several volts to be applied to the armature coil 2. occurs. This voltage is converted to DC by AVR6,
The field coil 3 is excited. When the field coil 3 is excited, the voltage generated by the armature coil 2 increases.
By repeating this operation, the power generation output gradually increases,
When the current value set by the current regulator 7 is reached, the field current becomes constant and the generated voltage becomes stable. The welding probe 10 moves the welding rod 11 to the welded part 12.
When it comes into contact with the metal, a current flows and an arc occurs. When the welding current flows, the voltage decreases due to the action of the reactor 4, and the welding current also becomes smaller.
A drooping characteristic as shown in FIG. 7 is obtained.

[Problem that the invention attempts to solve]

Generally, in an electric welder, when the welding rod 11 is brought closer to the part to be welded 12, the higher the no-load voltage, the easier the arc will fly, and the better the arc will start. Furthermore, it is known that when the welding rod 11 is welded to the welded part 12, in order to repel the welding rod 11 from the welded part 12 and maintain the arc, it is preferable that the flowing current be large. However, the sixth
In the conventional engine welder shown in the figure, when the welding current is set high by the current regulator 7, the no-load voltage increases as shown in characteristic a in FIG. When it is brought close to 12, the arc will fly more easily. However, if the welding current is set low, the no-load voltage becomes low, as shown by characteristic b in FIG. 7, making it difficult for the arc to fly. That is, the conventional engine welder has a drawback in that the no-load voltage changes depending on the set value of the welding current.

Furthermore, when the welding rod 11 is welded to the welded part 12, a short circuit occurs, so the short circuit current becomes 0, and the welding rod 11 remains welded to the welded part 12, so that the welding rod 11 is not blown away. , it becomes difficult to maintain the arc. As described above, the conventional engine welder has the drawback of poor arc characteristics in starting and maintaining the arc. Furthermore, there was a problem in that the shape of the reactor 4 needed to be large in order to obtain the drooping characteristic.

Therefore, the applicant of the present application has filed an application for an excellent electric welding machine that can eliminate all of the above-mentioned drawbacks and problems (Utility Application No. 70783/1983). To give an overview of the electric welding machine proposed by the applicant, two alternating current generators are rotationally driven by an engine, and one alternator is set to have a low no-load rated voltage and a high short-circuit current. However, the no-load rated voltage of the other alternator is set to be relatively high and the short-circuit current is small, and the outputs of the two alternators are rectified and combined to obtain the welding voltage. be. According to such electric welding machine,
A welding power source with a high no-load rated voltage and a large short-circuit current can be obtained. Therefore, when the welding rod is brought close to the welded part, the arc can be easily blown, the arc starting characteristics can be improved, and when the welding rod is welded to the welded part, a large short circuit current flows. Therefore, arc generation can be maintained well and arc characteristics can be improved.

However, the electric welding machine proposed by the applicant as described above requires two alternating current generators, resulting in a new problem of increased cost.

Therefore, the purpose of this invention is to provide a welding power supply device that has a simple and inexpensive configuration, can increase the no-load voltage, increase the short-circuit current at the time of short-circuit, and improve the arc characteristics. It is to provide.

[Means for solving problems]

This idea consists of an alternating current generator, an excitation circuit that rectifies the generated output of the alternator to provide an exciting voltage to the generator, and a rectifying circuit that rectifies the generated voltage of the alternator and outputs a welding voltage. Be prepared. The alternator generates an induced voltage based on a field coil that is rotationally driven by an engine and to which excitation voltage from the excitation circuit is applied, and fluctuations in the magnetic field generated by the rotation of the field coil. It includes a first armature coil and a second armature coil that also generates an induced voltage based on fluctuations in the magnetic field caused by rotation of the field coil. The first armature coil is selected such that its no-load rated voltage is relatively low and its short-circuit current is relatively large, and the second armature coil is selected such that its no-load rated voltage is relatively high and its short-circuit current is relatively high. chosen so that the current is relatively small.
Further, the rectifier circuit is configured to rectify and combine the induced voltage of the first armature coil and the induced voltage of the second armature coil, respectively, and output the welding voltage.

[Effect]

In this invention, one AC generator is provided with two sets of armature coils, and the characteristics of one armature coil are selected so that the no-load rated voltage is relatively low and the short-circuit current is relatively large, and the other The characteristics of the armature coils are selected so that the no-load rated voltage is relatively high and the short-circuit current is relatively small, and by combining the outputs of two sets of armature coils with these different characteristics, the This provides ideal output characteristics.

〔Example〕

FIG. 1 is an electrical circuit diagram showing an embodiment of this invention. In the figure, an alternating current generator G includes two sets of armature coils AC1 and AC2 with different characteristics provided on the same stator, and a field coil rotated within the stator by an engine (not shown).
Including FC. As will be described later, the first armature coil AC1 is selected to have characteristics such that its no-load rated voltage is relatively low and its short circuit current is relatively large. For this purpose, the first armature coil AC1 has a large conductor cross-sectional area and a small number of turns, resulting in low impedance. On the other hand, the second
The armature coil AC2 is selected to have characteristics such that its no-load rated voltage is relatively high and its short-circuit current is relatively small, as will be described later. For this purpose, the second armature coil AC2 has a conductor with a small cross-sectional area and a large number of turns, so that it has a high impedance. The first armature coil AC1 is connected to a rectifier DB1. This rectifier DB1 rectifies the voltage induced in the first armature coil AC1 and applies it to the terminals 8 and 9. On the other hand, the second armature coil AC2 is connected to the rectifier DB2. This rectifier DB2 rectifies the voltage induced in the second armature coil AC2 and applies it to the terminals 8 and 9. The welding power supply device shown in FIG. 1 is also provided with an excitation circuit 20 for exciting the field coil FC. This excitation circuit 20 includes a rectifier DB3. this rectifier
The induced voltage generated in the first armature coil AC1 is applied to DB3 via a reactor L and a resistor R. Further, the excitation circuit 20 includes a current transformer CT for detecting the load current flowing through the first armature coil AC1. The output of this current transformer CT is a rectifier
Given to DB3. Rectifier DB3 rectifies the induced voltage of first armature coil AC1 provided via reactor L and resistor R and the output provided from current transformer CT, and provides the rectified output to field coil FC.

Next, the operation of the embodiment shown in FIG. 1 will be explained. A field coil FC is generated by an engine (not shown).
When the motor is rotated at the rated rotational speed, magnetic field fluctuations occur due to the residual magnetism of the field coil FC, and a small induced voltage is generated in the first armature coil AC1 and the second armature coil AC2. first armature coil
The induced voltage generated in AC1 is applied to rectifier DB3 via resistor R and reactor L, and is rectified into a DC voltage. The rectified output of this rectifier DB3 is given to the field coil FC, causing a small current to flow through the field coil FC. Therefore, the magnetic flux generated by the field coil FC increases slightly, and the first armature coil AC
The induced voltages in the first and second armature coils AC2 become higher. By repeating these series of operations, the voltages generated by the first armature coil AC1 and the second armature coil AC2 gradually approach the rated voltage, and become stable when the rated voltage is reached. The alternating current voltages generated in the first armature coil AC1 and the second armature coil AC2 are, respectively,
After being rectified into a DC voltage by rectifiers DB1 and DB2, the combined voltage is applied to terminals 8 and 9. Therefore, from the terminals 8 and 9, the first armature coil AC1 and the second armature coil AC2
A DC voltage that is a composite of the generated voltages is output.

Here, the welding rod 11 is
When brought into contact with the part to be welded 12, welding current flows and an arc is generated. At this time, a load current flows through the first armature coil AC1 and the second armature coil AC2. Fluctuations in the load current flowing through the first armature coil AC1 are detected by the current transformer CT and fed back to the field coil FC via the rectifier DB3. That is, the excitation circuit 20 performs excitation proportional to the voltage by the reactor L to give the alternator G a shunt characteristic, and the current transformer CT
Excitation is performed in proportion to the current to give the alternator G a series winding characteristic. This allows the alternator G to have compound winding characteristics. That is, the terminal voltage can be kept constant regardless of the magnitude of the load current.

Next, the characteristics or advantages of the embodiment shown in FIG. 1 will be explained. Figure 2 shows the first armature coil AC1.
It is a graph showing the static characteristics of. The static characteristics shown in Figure 2 were obtained by disconnecting the second armature coil AC2 from terminals 8 and 9, then connecting variable resistors to terminals 8 and 9, and examining changes in terminal voltage due to load fluctuations. be. Figure 3 shows the armature coil in Figure 2.
It is a graph showing static characteristics of AC2. The static characteristics shown in Fig. 3 indicate that the first armature coil AC1 is connected to terminal 8.
After disconnecting from terminals 8 and 9, variable resistors were connected to terminals 8 and 9, and changes in terminal voltage due to load fluctuations were investigated. As shown in the diagram, the first armature coil AC1 has a no-load rated voltage of 25 to 30V.
It has a characteristic that the current is relatively large during a short circuit. On the other hand, the characteristics of the second armature coil AC2 are selected such that the no-load rated voltage is relatively high at 80 to 60V, and the current at the time of short circuit is relatively small at 10 to 20A. When the voltages generated by the first armature coil AC1 and the second armature coil AC2 having such different characteristics are rectified and combined, the change in terminal voltage with respect to load fluctuation becomes as shown in FIG. 4. That is, it has the characteristics of a high no-load rated voltage and a large current during short circuit. Therefore, the welding rod 111
When the welding rod 11 is brought close to the welded part 12, the arc can be easily blown, and the arc starting characteristics can be improved, and when the welding rod 11 is welded to the welded part 12, the short circuit current is large, so the arc cannot be maintained. This can improve arc characteristics. In addition, in FIG. 4, the line X is the static characteristic when the no-load voltage of the first armature coil AC1 is set to 35V,
Line Y represents the no-load voltage of the first armature coil AC1.
Static characteristics when set to 25.5V.

Figure 5 shows the first armature coil AC1 and the second armature coil AC1.
3 is a graph showing changes in the generated voltage and load current of each armature coil AC2. Note that FIG. 5a is a graph of changes in the voltage generated in the first armature coil AC1 measured by the voltmeter 21 in FIG. 1, and FIG. This is a graph obtained by measuring changes using the ammeter 22 in FIG. 1. Also, Fig. 5c shows the second armature coil.
FIG. 5d is a graph showing changes in the generated voltage of AC2 measured with the voltmeter 23 in FIG. 1, and FIG. 5d is a graph showing changes in the load current of the second armature coil AC2 measured with the ammeter 24 in FIG. It is. Referring to FIG. 5, further advantages of the embodiment shown in FIG. 1 will be explained. As shown in FIG. 5, under no load, voltages V1 and V2 are stable at the rated voltages, and load currents A1 and A2 are zero. Here, when a load is connected to terminals 8 and 9 and the load is applied, the first armature coil AC1 is selected to have low impedance as described above.
A large load current A1 flows, and the generated voltage V1 decreases. On the other hand, since the second armature coil AC2 is selected to have high impedance as described above, the load current A2 does not have a very large value. Here, the voltage V2 generated by the second armature coil AC2 should normally decrease from the rated voltage due to the flow of the load current A2.
As shown in Figure c, the voltage has increased slightly from the rated voltage. This is because when a large load current A1 flows through the first armature coil AC1, the generated magnetic flux increases, and a part of the increased generated magnetic flux is transferred to the second armature coil AC1.
This is because it acts as a magnetizing effect on the armature coil AC2. That is, since the power factor of the arc welding load is approximately 1, the first armature coil AC1 generates a magnetomotive force that is delayed by approximately 90 degrees in electrical angle. This is the so-called cross magnetization effect. This 90° lag magnetomotive force is
Increase the magnetic flux interlinking with the second armature coil 2,
It functions to increase the induced voltage of the second armature coil AC2. Therefore, as when changing from no load to loaded, the first armature coil AC1
When the load current increases rapidly, the increase in the generated voltage due to the magnetizing effect exceeds the decrease in the generated voltage caused by the flow of the load current, and the generated voltage in the second armature coil AC2 increases. This increases V2 above the rated voltage. Such a phenomenon also occurs when the welding rod 11 is welded to the part to be welded 12 and a short circuit occurs. That is, when the welding rod 11 and the part to be welded 12 are welded together, a large short-circuit current flows through the first armature coil AC1, increasing the voltage V2 generated at the second armature coil AC2. Thereby, it is possible to prevent the terminal voltage of the terminals 8 and 9 from rapidly decreasing, and it is possible to maintain the arc voltage and maintain the arc. Therefore, arc characteristics can be further improved. Furthermore, in order to achieve this effect,
The second armature coil AC2 is the first armature coil
It is necessary to place it in a position where it can receive the magnetizing effect from AC1. Therefore, in this embodiment, the second armature coil AC2 is arranged at a position delayed by approximately 90 degrees in electrical angle with respect to the first armature coil AC1.

Additionally, the current transformer CT quickly feeds back changes in load to the field coil FC.
This is considered to be a cause of increasing the induced voltage in the second armature coil AC2.

[Effects of the invention] As described above, according to this invention, the first armature coil has characteristics such that the no-load rated voltage is relatively low and the short-circuit current is relatively large, and the no-load rated voltage is Since the welding voltage is obtained by rectifying and combining the respective outputs of the second armature coil, which has characteristics such that the short-circuit current is relatively high and the short-circuit current is relatively small, the no-load rated voltage is high and the short-circuit current is high. A welding power source with a large current can be obtained. Therefore, the arc can be easily blown at the start of welding, improving the arc starting characteristics, and a large short-circuit current can be passed when the weld is welded, so that arc generation can be maintained well. Furthermore, with this invention, only one alternating current generator needs to be provided, and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of this invention. 2 and 3 are graphs showing the static characteristics of the first armature coil AC1 and the second armature coil AC2 shown in FIG. 1, respectively. FIG. 4 is a graph showing the static characteristics of the embodiment shown in FIG. FIG. 5 is a graph showing changes in the generated voltage and load shunt of each of the first armature coil AC1 and the second armature coil AC2 shown in FIG. 1. FIG. 6 is an electrical circuit diagram of a conventional engine welder. FIG. 7 is a diagram showing the voltage-current characteristics of the engine welder shown in FIG. 6. In the figure, G is an alternating current generator, FC is a field coil, AC1 is a first armature coil, AC2 is a second armature coil, 20 is an excitation circuit, L is a reactor, CT is a current transformer, and DB1 to DB3 is a rectifier, 10
11 is a welding probe, 12 is a welding part, and 12 is a welding part.

Claims (1)

[Claims for Utility Model Registration] (1) A welding power supply device that is driven by an engine and generates electric power for arc welding, which is an alternating current generator that is rotationally driven by the engine and generates electricity. , and an excitation circuit that rectifies the generated output of the alternator to provide an excitation voltage to the generator, wherein the alternator is rotationally driven by the engine, and the excitation voltage from the excitation circuit is An induced voltage is generated based on an applied field coil and fluctuations in the magnetic field caused by the rotation of the field coil, and is selected so that its no-load rated voltage is relatively low and its short-circuit current is relatively large. generates an induced voltage based on fluctuations in the magnetic field caused by the rotation of the first armature coil and the field coil, and has a relatively high no-load rated voltage and a relatively small short-circuit current. a second armature coil selected from the above, and further rectifies and combines the induced voltage of the first armature coil and the induced voltage of the second armature coil, respectively, and outputs a welding voltage. A welding power supply device equipped with a rectifier. (2) The welding power supply device according to claim 1, wherein the second armature coil is arranged at a position where it can receive a magnetizing action from the first armature coil. (3) The welding power supply device according to item 2 of the scope of utility model registration, wherein the second armature coil is arranged at a position delayed by approximately 90 degrees in electrical angle with respect to the first armature coil. (4) The first armature coil is selected to have a relatively low impedance, and the second armature coil is selected to have a relatively high impedance. The welding power supply device according to any one of Item 3. (5) The welding power supply device according to any one of claims 1 to 4, wherein the excitation circuit includes a circuit that rectifies the induced voltage of the first armature coil. (6) The excitation circuit includes a current transformer that detects the load current of the first armature coil, and a current transformer that combines the induced voltage of the first armature coil and the detection output of the current transformer, respectively. Claim 1 of the utility model registration, which includes a rectifier for rectification.
The welding power supply device according to any one of items 1 to 4.