JPS6213105B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a field control device for an engine-driven welding generator that allows desired external output characteristics to be obtained at will. Conventionally, a portable engine-driven welding generator has been used as a power source for welding work at construction sites, especially metal cladding arc welding (hand welding). Direct current generators of the third brush type, Rosenberg type, or differential compound type were used exclusively, which were made to have droop characteristics with good arc stability. All of these methods appropriately apply basic means for obtaining external output characteristics suitable for arc welding. Therefore, all of the above generators are special DC generators, and in addition to having complex structures and complicated manufacturing and repair work, they are also large in weight and shape, and are not necessarily suitable for portable use. And it was expensive. On the other hand, in recent years at construction sites, automatic or semi-automatic welding, in which a large current is passed through consumable small-diameter electrodes, has been implemented in order to improve work efficiency and welding quality. Moreover, since automatic or semi-automatic welding requires a power source with constant voltage characteristics, a dedicated engine-driven welding machine is installed, and if the welding area is long, automatic or semi-automatic welding is performed to ensure that the welding area is If the number of welding machines is small or if an automatic (semi-automatic) welding machine cannot be installed, manual welding will have to be done as usual, so we recommend two types of dedicated engines with external output characteristics: drooping characteristic type and constant voltage characteristic type. It was necessary to install a drive-type welding generator. Furthermore, the automatic (semi-automatic) welding machines mentioned above do not necessarily have excellent perfectly horizontal constant voltage characteristics due to differences in working conditions such as the feeding method of consumable electrodes and the material of the welding base material. In some cases, the drooping characteristics (the degree of drooping is different from the drooping characteristics during manual welding) are excellent. Similarly, in manual welding, depending on various conditions such as the welding base material, welding rod material, welding posture, etc., completely vertical constant current and high droop ratio near constant current are not necessarily superior. In some cases, a device with a small droop ratio is required. In addition to these, there are a wide variety of welding and arc cutting methods such as TIC welding, submerged welding, carbon dioxide welding, and arc gouging, which require characteristics with different degrees of droop, from constant current characteristics to constant voltage characteristics. There has been a strong desire for a portable engine-driven welding generator that can output all of these characteristics. The present invention has been made in view of the above circumstances, and is an engine-driven welding type that can change the external output characteristics of a welding generator to constant current characteristics, constant voltage characteristics, or drooping characteristics that can arbitrarily change the degree of droop depending on the needs of welding work. The purpose of the present invention is to provide a field control device for a power generator. In order to achieve the above object, the present invention winds an excitation winding around an iron core around which an armature winding is wound, connects the excitation winding to a delta connection with one end open, and connects the excitation winding to a delta connection with one end open. In a self-excited shunt engine-driven welding generator that excites a field winding with a direct current obtained by combining a current and a phase current of the excitation winding,
Load current detection means and load voltage detection means are provided between the armature winding and the output terminal, one input terminal of a subtracting amplifier is connected to the load current detection means via an on/off switch, and the load current detection means is connected to the load current detection means via an on-off switch. Connect one input terminal of the comparator via a switch, connect the reference voltage setting power supply to the other input terminal of the subtracting amplifier, and connect the output terminal of the subtracting amplifier to the other input terminal of the comparator. A load voltage detection means is connected to a changeover switch of one input terminal of the comparator, and an output terminal of the comparator is connected to a field current control means. It is characterized by a field control device. Embodiments according to the present invention will be described below with reference to the drawings. FIG. 1 is an electrical wiring diagram of an embodiment according to the present invention. In the figure, 1 is a generator whose field poles are rotationally driven by an engine (not shown), and has three-phase star-connected armature windings A, B, C,
In addition to having a field winding Fg which is rotationally driven with O,
It has delta-connected excitation windings E, F, G, and H which are wound on the same core as the armature windings A, B, C, and O, and have one end open. 2 is a first circuit that performs full-wave rectification of the outputs of armature windings A, B, C, and O of generator 1.
It is a rectifier circuit, and one end of this rectified output is connected to the welding output terminal 12 via the load current detection resistor _R1 , which is the load current detection means of the generator 1, and the other end is connected to the welding characteristic improvement reactor 5. and is connected to the welding output terminal 11. 3 is the excitation winding E of the generator 1,
A second rectifier circuit that rectifies the output of each winding interconnection point F, G and the output of the open ends E, H, and supplies this rectified output to the field winding Fg. be. In the above device, the present invention provides the field current control through a field winding Fg in which a flywheel diode 4 connects both ends of the rectified output of the second rectifier circuit 3 in a direction opposite to the direction of the exciting current. It is connected to the collector and emitter of the field control transistor 6 which is the means. Then, the field control transistor is controlled by a signal calculated by combining a load voltage detection signal, a load current detection signal, and a setting reference voltage signal of the generator 1, which will be described later, using a switch, a subtraction amplifier, and a comparator. Drives the base of 6,
This provides the generator 1 with desired external output characteristics. That is, the output of the second rectifier circuit 3 is connected to the power supply stabilizing circuit 10 as the reference voltage setting power supply, and the constant voltage output terminal 10a of the circuit 10 outputs the reference voltage. The primary winding of the load voltage detection transformer 7, which is the load voltage detection means of the generator 1, is an armature winding A,
The output of the secondary winding, which is connected between winding ends B and C of B, C, and O and has an intermediate tap, is connected to the resistor through a waveform shaping circuit formed by resistors R ₇ and R ₈ and capacitor C ₂ . A rectified voltage of the generator 1 containing a ripple component is generated across _R8 . The voltage due to the detected load current generated at the load current detection resistor R ₁ of the generator 1 is detected by the resistor R ₂ and the variable resistor.
The voltage is divided into a DC voltage including ripple by a waveform shaping circuit equipped with a voltage divider consisting of VR ₁ , resistor R ₃ , and capacitor C ₁ , and the variable terminal of variable resistor VR ₁ is subtracted via switch SW ₂ . Connected to the (-) input terminal of amplifier IC ₂ . A constant voltage output terminal 10a of the power supply stabilization circuit 10 is connected to one end of a load current detection resistor R1 via a resistor _R4 , a semi-fixed variable resistor _VR2 fixed at the factory, and _a resistor _R5 . . Terminal a 3 of the changeover switch SW ₃ connected to the variable terminal of the variable resistance VR ₂ , and terminal B of the changeover switch SW ₃ connected to the variable resistance terminal of the variable resistance VR ₃ connected in parallel to _the variable resistance VR ₂ . ₃ is connected to the (+) input terminal of the subtraction amplifier IC ₂ through the switching piece of the changeover switch, and subtracts the input voltage of the (-) terminal from the input voltage of the (+) terminal, and the feedback resistor R Subtraction amplifier amplified by the action of ₆
The output signal of IC ₂ is sent to the (+) input terminal of comparator IC ₁ . Terminal A ₁ of changeover switch SW ₁ connected to the (-) terminal of the detected load voltage including the ripple component, and a variable resistor by dividing the detected load current signal.
Changeover switch SW ₁ connected to variable terminal of VR ₁
The terminal _b1 of is connected to the (-) input terminal of the comparator _IC1 via the switching piece of the changeover switch _SW1 . The output terminal of this comparator IC ₁ is connected to the base of the field control transistor 6. According to the above configuration, the changeover switch SW ₁ SW ₃
as appropriate, and turn on/off switch SW ₂ ON/OFF
By doing so, the external output characteristics of the generator 1 are changed as shown in Table 1.

[Table] That is, a case will be described in which a constant voltage characteristic is given to the generator 1 as an external output characteristic. First, as shown in Table 1, the switching piece of the switching switch SW ₁ is connected to the terminal a ₁ , the open/close switch SW ₂ is turned off, and the switching piece of the switching switch SW ₃ is connected to the terminal B ₃ . By operating this switch, the set reference voltage is supplied from the power supply stabilization circuit 10 to the (+) terminal of the subtraction amplifier IC ₂ via the variable terminal of the variable resistor VR ₂ , and the (-)
Since the on/off switch _SW2 is OFF and there is no input signal to the terminal, the set reference voltage is introduced to the (+) input terminal of the comparator _IC1 via the output terminal of the subtraction amplifier _IC2 . On the other hand, since the detected load voltage including the ripple component is input to the (-) input terminal of the comparator IC ₁ , the result is as shown in FIG. In the figure, a straight line 21 indicates the input voltage waveform at the (+) terminal of the comparator IC ₁ , and a curve 22 indicates the input voltage waveform at the (-) terminal. And the input voltage of the (+) terminal is (-)
During the period when the input voltage is higher than the terminal input voltage, the comparator IC ₁ sends an output signal to the base of the field control transistor 6 to turn on the transistor 6 as shown by curve 23, so that the input voltage at the (+) terminal is higher than that at the (-) terminal. Comparator IC ₁ does not send out an output signal when it is smaller than the input voltage. For this purpose, the field control transistor 6
becomes OFF. That is, the field winding of generator 1
Fg is excited so that the external output characteristic becomes a constant voltage characteristic. The voltage value range exhibiting constant voltage characteristics is determined by adjusting the variable resistor _VR3 as shown in FIG. Next, when giving constant current characteristics to the generator 1 as an external output characteristic, as shown in Table 1, connect the switching piece of the changeover switch SW ₁ to the terminal b ₁ , and turn off the on/off switch SW ₂ . as a changeover switch
Connect the movable piece of SW ₃ to terminal A ₃ . By operating this switch, the set reference voltage is supplied from the power supply stabilization circuit 10 to the (+) terminal of the subtraction amplifier IC ₂ via the variable terminal of the variable resistor VR ₂ , but since the open switch SW ₂ is OFF. Since there is no input signal at the (-) terminal, this set reference voltage is a subtraction amplifier.
It is introduced into the (+) terminal of comparator IC ₁ via the output of IC ₂ . A signal voltage of the detected load current including a ripple component is supplied to the (-) input terminal of the comparator IC ₁ via the variable terminal of the variable resistor VR ₁ . In FIG. 4, a straight line 41 represents the input voltage waveform at the (+) terminal of the comparator IC ₁ , and a curve 42 represents the input voltage waveform at the (-) terminal. And (+)
Comparator IC ₁ sends an output signal to the base of field control transistor 6 to turn ON transistor 6 as shown by curve 43 only during the period when the input voltage at the terminal is higher than the input voltage at the (-) terminal. Therefore, the field winding Fg of the generator 1 is excited so that the external output characteristic becomes a constant current characteristic. The current value width showing the constant current characteristic is determined by the variable resistor as shown in Figure 5.
This is done by adjusting VR ₁ . Next, when giving the drooping characteristic as the external output characteristic of the generator 1, as shown in Table 1, connect the switching piece of the changeover switch _SW1 to the terminal _a1 , turn on the on/off switch _SW2 , Connect the changeover piece of changeover switch SW ₃ to terminal A ₃ . By operating this switch, the voltage stabilizing circuit 10 is connected to the (+) terminal of the subtraction amplifier IC ₂ via the variable terminal of the variable resistor VR ₂ .
A set reference voltage is supplied from the (-) terminal as shown by the straight line 61 in _FIG . The subtraction amplifier IC ₂ sends an output signal as shown by the straight line 63 in FIG. 6 to the (+) input terminal of the comparator IC ₁ only when the voltage is supplied as shown in FIG. On the other hand, the (-) input terminal of the comparator IC ₁ is supplied with the single-phase full-wave rectified load voltage of the generator 1 including a ripple component, as shown by a curve 71 in FIG. Moreover, the signal supplied to the (+) input terminal of comparator IC ₁ is the one obtained by subtracting and amplifying the load current value from the set reference value, and the load current is obtained by subtracting and amplifying the load current value from the set reference value. Since the waveform is rectified, the voltage at the (+) input terminal of comparator IC ₁ is
This results in a waveform shown by curve 72 in the figure. and the input voltage with waveform 72 at the (+) terminal is (-)
Comparator IC ₁ outputs a pulse signal shown in waveform 73 in FIG. 7 to the base of field control transistor 6 only when the input voltage with waveform 71 at terminal is control the excitation current. That is, the input voltage of the (+) terminal of the comparator IC ₁ is the output voltage of the subtraction amplifier circuit IC ₂ , that is, the voltage that decreases as the detected welding current increases,
The input of the (-) terminal is the welding voltage, and during the period when the input voltage of the (-) terminal is lower than the (+) terminal voltage, the output of the comparator IC ₁ is transmitted through the field control transistor 6 to the excitation current of the field winding. The field winding is controlled so that the welding voltage has a drooping characteristic with respect to the welding current.
The current of Fg will be controlled. The drooping characteristic is shown as a straight line 81 in FIG. 8, and the drooping characteristic can be adjusted to a desired degree by adjusting the variable resistor VR ₁ that detects the welding current.
This adjustment is usually made between straight line 82 and straight line 8, which are indicated by dashed lines.
Although it is used within a range of about 3, it is also possible to use it outside that range. From the above explanation, this embodiment uses one welding generator and changes the external output characteristics to constant voltage characteristics and constant voltage characteristics by operating a changeover switch and a variable resistor as needed for welding work. Current characteristics and drooping characteristics with a desired degree of droop can be imparted. Although the voltage was detected by full-wave rectification of the output of the transformer 7, half-wave rectification is also possible. In summary, the present invention winds an excitation winding around an iron core wrapped with an armature winding, connects the excitation winding to a delta connection with one end open, and connects the zero-sequence current from the open end of the delta tangent. In a self-exciting shunt welding generator that excites a field winding with a DC current obtained by combining the phase current of the excitation winding, a load is placed between the armature winding and the output terminal. A current detection means and a load voltage detection means are provided, and one input terminal of a subtraction amplifier is connected to the load current detection means via an on/off switch, and one input terminal of a comparator is connected to the load current detection means via a changeover switch. A reference voltage setting power supply is connected to the other input terminal of the subtracting amplifier, and the output terminal of the subtracting amplifier is connected to the other input terminal of the comparator, and one input terminal of the comparator is connected to the other input terminal of the subtracting amplifier. Since the load voltage detection means is connected to the side changeover switch and the output terminal of the comparator is connected to the field current control means, a complicated structure such as a third brush type or Rosenberg type is used to provide drooping characteristics. This has the important effect that constant voltage characteristics, constant current characteristics, and desired droop characteristics can be provided at any time according to the requirements of welding work using a single generator.

[Brief explanation of the drawing]

FIG. 1 is an electrical connection diagram of an embodiment according to the present invention, and FIGS. 2 to 8 are diagrams for explaining the operation of external output characteristics of the embodiment according to the present invention.
3 is for constant voltage characteristics, FIGS. 4 and 5 are for constant current characteristics, and FIGS. 6, 7, and 8 are for droop characteristics. DESCRIPTION OF SYMBOLS 1... Generator, 2... First rectifier circuit, 3... Second rectifier circuit, 4... Flywheel diode, 5... Reactor, 6... Field control transistor, 7... Load voltage detection transformer, 8, 9... Diode, 10... Power supply stabilization circuit, 11, 12... Output terminal for welding,
R ₁ ...Load current detection resistor, IC ₁ ...Comparator, IC ₂ ...
Subtraction amplifier, Fg...field winding, EFGH...delta connection excitation winding with one end open.

Claims (1)

[Claims] 1. An excitation winding is wound around an iron core around which an armature winding is wound, and the excitation winding is connected to a delta connection with one end open, and the zero-sequence current of the delta connection and the phase current of the excitation winding are In a self-excited shunt-winding engine-driven welding generator that excites a field winding with a combined DC current, a load current detection means and a load voltage are provided between the armature winding and the output terminal. A detection means is provided,
One input terminal of the subtracting amplifier is connected to the load current detecting means via an on/off switch, and one input terminal of a comparator is connected to the load current detecting means via a changeover switch. A reference voltage setting power supply is connected to the input terminal, and the output terminal of the subtraction amplifier is connected to the other input terminal of the comparator, and a load voltage detection means is connected to the changeover switch on the one input terminal side of the comparator. 1. A field control device for an engine-driven welding generator, characterized in that the output terminal of the comparator is connected to field current control means.