JPH0530856Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to an improvement of an arc machining device used when machining a load using arc output.

Examples of arc processing equipment include a plasma arc cutting layer that outputs arc plasma to cut a workpiece, and an arc welder that arc welds a workpiece. The present invention relates to an arc machining device that can safely set the device to a driving state according to the type of external power supply voltage by determining the type of the power supply voltage even when using AC external power supplies of different levels.

[Background technology]

This type of prior art includes, for example, using 200V AC as a power source when first used, and then
When using AC100V, the type of external power source is determined and the internal circuit of the arc processing device can be automatically switched from AC200V specification to AC100V specification according to the type.

However, with such prior art, when the external power supply is repeatedly turned on and off,
Unable to adapt to these changes, the system may end up with a 100V specification even when a 200V power supply is being supplied, making it impossible to perform safe control and creating problems in terms of internal circuit safety measures.

In addition, conventional arc processing equipment having the above-mentioned functions is equipped with an inverter circuit in the drive section.
Although efforts are being made to improve load control efficiency,
The control unit that sends control signals to the inverter circuit is driven by inputting an AC external power source that is a commercial frequency, and converts this input external power source to a certain level in an internal circuit to control the inverter circuit of the drive unit. Because it was configured to send out signals, the transformer for voltage level conversion became larger.
This was an impediment to efforts to make it smaller and lighter.

[Purpose of invention]

This invention was developed in view of the above circumstances, and uses two AC external power supplies with different voltage levels, and even when the external power supplies are repeatedly turned on and off, the external power supply voltage It is an object of the present invention to provide an arc machining device in which the internal circuit can be safely set to a driving state according to the driving conditions, and the entire device can be made small and lightweight.

[Structure of the idea]

The present invention proposed to achieve the above purpose is:
This is an improvement of an arc machining device that distinguishes the type of external power supply voltage with two different voltage levels and automatically sets the device to a driving state according to the external power supply. An input voltage automatic switching circuit that has a voltage discrimination circuit that determines the type of external power supply and outputs a switching signal when it determines that the external power supply voltage is at a lower level voltage, and switching from this input voltage automatic switching circuit. A voltage adjustment circuit that converts and outputs an input external power supply to a constant level DC drive voltage by switching control according to a signal, and a constant level DC drive voltage output from this voltage adjustment circuit. an inverter drive unit that operates in response to the drive voltage, an output detector that detects the output being supplied to the load, and an output unit that supplies the output from the inverter drive unit to the load; A control unit receives a DC drive voltage of a constant level from the circuit, supplies drive power to a control circuit via a DC-DC converter, and outputs a control signal from the control circuit to the inverter drive unit. When the voltage discrimination circuit of the input voltage automatic switching circuit determines that the external power supply is at the lower voltage level, it outputs a switching signal after a predetermined delay time has elapsed and changes the voltage to the above voltage. The feature is that the adjustment circuit can be automatically switched and set according to the type of external power supply voltage.

〔Example〕

Hereinafter, the present invention will be explained with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the basic configuration of the arc machining apparatus of the present invention.

In the figure, reference numeral 1 denotes a voltage adjustment circuit which converts the voltage level of an input AC external power supply Vin and supplies the inverter drive section 2 with a constant level DC drive voltage Vo. Reference numeral 2 denotes an inverter drive section controlled by the control section 3, which supplies a predetermined output to the load via the output section 5. The control section 3 is supplied with the driving voltage Vo from the voltage adjustment circuit, and performs feedback control so that the output detected by the output section 5 matches a set value.

In the present invention, the control unit 3 receives a DC drive voltage Vo of a constant level from the voltage adjustment circuit, drives the DC-DC converter 31, converts it into a high frequency signal of a predetermined frequency, and converts it into a high frequency signal of a predetermined level. The control circuit 32 is configured to supply a DC drive power source to the control circuit 32, and therefore the control unit 3 is connected to an AC external power source.
Since there is no need to process Va (or Vb) and the drive voltage Vo is converted to a high frequency, the transformer in the internal circuit can be made smaller and lighter.

The DC signal output from the control circuit 32 of the control section 3 becomes a control signal for the inverter drive section 2 and performs feedback control of the above-mentioned inverter drive section 2.

In addition, in the present invention, the voltage level of the AC external power supply Vin is determined by the input voltage automatic switching circuit 4, and if the voltage level of the external power supply is the lower one (Va), the voltage level of the AC external power supply Vin is determined after a predetermined delay time. , outputs a switching signal to the voltage adjustment circuit. When the voltage adjustment circuit receives this switching signal, it is controlled and set to a state according to the voltage level of the input external power supply Vin, and thereby the voltage adjustment circuit drives the subsequent inverter regardless of the type of external voltage Vin. A voltage Vo at a constant level is outputted to the section 2.

On the other hand, the input voltage automatic switching circuit 4 has a voltage discrimination circuit for discriminating the type of the input AC external power supply Vin, and has two voltage levels Va and Vb.
A reference voltage that can discriminate is set as the discrimination level.

In the present invention, the arc processing device is initially set to a state where the voltage adjustment circuit 1 can be driven by receiving the external power supply at the higher voltage level (Vb) before turning on the external power supply. This state is maintained until the lower one (Va) is input. However, when the automatic input voltage switching circuit 4 determines that the lower voltage level (Va) is input as the external power supply, it outputs a switching signal after a predetermined delay time and switches the voltage adjustment circuit 1 to the lower external power supply (Va). Va).

The delay time of the switching signal in the present invention is provided to ensure that the input voltage automatic switching circuit 4 switches operation reliably and safely even when the power to the arc processing device is frequently turned on and off. As is clear from the examples described later, the time is
The output of the switching signal is suppressed until the input voltage reaches the discrimination level after the external power is turned on.

FIG. 2 is a block diagram showing the device of the present invention in more detail.

The voltage adjustment circuit 1 includes four diodes 1a to 1.
Two capacitors 1f and 1g of the same capacity are placed on the output side of the diode bridge DB formed by d.
Connect the relay contact CR between the series circuit of capacitors 1f and 1g and the diode bridge DB.
1 (a contact) interposed therebetween.

This relay contact CR1 is driven by a switching signal from the input voltage automatic switching circuit 4, and when the input voltage automatic switching circuit 4 determines that the external power supply Vin is at the lower level (Va), the relay contact CR1 is driven by a switching signal from the input voltage automatic switching circuit 4.
If CR1 is closed and vice versa, relay contact CR1
becomes open.

When the external power supply with the higher voltage level (Vb) is input and the relay contact CR1 opens, the voltage regulator circuit 1 forms a full-wave rectifier circuit using the diode bridge DB, and the output becomes Vo. When the lower (Va) external power supply is input and the relay contact CR1 is closed, the voltage adjustment circuit 1 connects the capacitor 1f,
Since a voltage doubler circuit is formed by connecting 1g series circuits, the output will be Vo in the same way.

Further, the control unit 3 has a DC-DC converter 31, in which a constant level drive voltage Vo outputted from the voltage adjustment circuit 1 is input as a drive voltage, and is changed into a high frequency signal of a predetermined frequency. The signal is converted back into a DC signal to supply driving power to the control circuit 32. The control circuit 32 outputs a control signal to the inverter drive unit 2.

Next, the configuration and operation of the automatic input voltage switching circuit will be specifically explained with reference to FIG.

FIG. 3 shows a detailed internal circuit of the input voltage automatic switching circuit 4, which constitutes the main part of the present invention. In the example below, Vref2<Vref1 is set,
It is configured to output a switching signal when Vref2<V1<Vref1.

As shown in the figure, input voltage automatic switching circuit 4
has a diode D1 and a smoothing capacitor C1 to convert the input AC power supply Vin into DC, and has two comparators to determine the voltage level of the input external power supply Vin and output a switching signal.
It is equipped with COMP1, COMP2, transistor TR, and relay Ry.

The switching signal is generated by turning on the transistor TR, and in the example shown, the switching signal is generated by turning on the transistor TR.
2 and resistor R6 set the delay time.

To explain its configuration, the AC power supply Vin at a predetermined voltage level has a diode D1 and a smoothing capacitor C1.
comparator COMP as the voltage shared by resistor R2 in the series circuit of resistors R1 and R2.
1 input voltage V1.

Here, the comparator COMP1 sets Vin to the resistance R of the DC circuit formed by the resistances R5, R3, and R4.
The shared voltage of 4 is set as a reference voltage Vref1, and this reference voltage Vref1 is held constant by the Zener diode ZD during steady state after inputting an external power supply.

On the other hand, the comparator COMP2 converts the voltage across the capacitor C2, which is charged via the resistor R6 by the output voltage of the smoothing capacitor C1, to the input voltage V
2, and the shared voltage of resistor R9 in the series circuit of resistors R5, R8, and R9 is set as reference voltage Vref2, and the configuration is such that the electric charge charged in capacitor C2 can be controlled to be discharged by comparator COMP1 via diode D2. . The reference voltage Vref2 of the comparator COMP2 is also maintained at a constant level by the Zener diode ZD described above during normal operation after power is turned on.

The output terminal of comparator COMP2 is connected to resistor R
The transistor TR is connected to the base of the transistor TR via the comparator COMP2, and the transistor TR is controlled to be turned on and off by the output of the comparator COMP2, and a switching signal is outputted by driving the relay Ry.

Note that D3 is provided to absorb surge current that occurs when relay Ry is turned off.

Next, the operation of the automatic input voltage switching circuit will be explained with reference to Figs. 4 and 5. When an external power supply with a higher voltage level Vb is input now, V1 increases as smoothing capacitor C1 is charged. It gradually rises and reaches the reference voltage Vref1 after a predetermined time To has elapsed. During this To period, the capacitor C2 is also charged via the resistor R6 to increase its output, but in the present invention, the time constant τ (=R
By appropriately selecting the setting of 6×C2), the voltage V2 across the capacitor C2 is set to the comparator COMP2.
Since it is set not to exceed the reference voltage Vref2 of the comparator COMP2, the output of the comparator COMP2 is "H".
Therefore, the switching signal is not output and the device is not driven.
It is set and maintained in a state where it can be driven by an external power supply of Vb.

Moreover, after the time To has elapsed, V1 further increases,
It reaches a steady state and reaches a certain saturation level, but V
1 exceeds the reference voltage Vref1, the comparator COMP1 outputs the "L" level, and the charge stored in the capacitor C2 is discharged via the diode D2.

As a result, V2 becomes lower than the reference voltage Vref2, and the comparator COMP2 maintains the output at the "L" level and turns off the transistor TR, so that no switching signal is output.

After V1 reaches the saturation level, when the power supply voltage is cut off, the level of V1 gradually decreases, and finally reaches the reference level Vref.
It becomes lower than 1. At this time, the comparator COMP
1 changes to "H" level output, and capacitor C2
The discharging of the capacitor C2 is stopped, and the capacitor C2 starts charging again, but as the power supply voltage decreases, the voltage V2 across it also gradually decreases, and the transistor TR remains in the OFF state, and the switching signal is not output. First, the device is set and held in a driveable state by a high voltage level (see FIG. 4).

On the other hand, when an external power supply with a lower voltage level Va is input, V1 gradually rises as smoothing capacitor C1 is charged, but in this invention, even if V1 reaches the saturation level at this time, the Voltage
It is set so that it does not reach Vref. Therefore, the comparator COMP1 outputs an "H" level, and the discharge of the capacitor C2 is prevented.

As a result, the capacitor C2 is charged via the resistor R6, and the voltage V2 across the capacitor C2 is
exceeds the reference voltage Vref2 of comparator COMP2, the output of comparator COMP2 becomes “H”
Then, the transistor TR is turned on, the relay Ry is driven, a switching signal is output, and the device is set to a state where it can be driven by the external power supply of the lower voltage level Va.

This switching signal means that the input external power supply is cut off and the voltage V2 across the capacitor C2 is set to the reference voltage.
It is held until it drops below Vref2, and when the voltage V2 across the capacitor C2 falls below the reference voltage Vref2,
The switching signal is released and the device is set in its initial state, ie, in a state in which it can be driven by the supply voltage at the higher level Vb (see FIG. 5).

Therefore, according to the present invention, even if the power supply voltage is turned on frequently, the internal circuit is not damaged because the system is not set to be driven by an external power supply at a low voltage level. It is completely safe. In addition, in the above-mentioned embodiment, the delay circuit was provided on the input side of the comparator COMP2, but
It goes without saying that it may be provided on the output side of the comparator COMP2, and a circuit configuration diagram in that case is shown in FIG.

[Effect of idea]

As understood from the above explanation, according to the present invention, the switching signal output from the input voltage automatic switching circuit that determines the voltage level of the external power supply is output after a delay of a predetermined time after the power is turned on. Therefore, even if the external power source is turned on and off frequently, a switching signal is not output, and the drive state of the device can be safely and reliably adjusted against fluctuations in input voltage.

In addition, in the present invention, the control section of the inverter drive section is configured with a DC-DC capacitor, and the voltage adjustment circuit converts the AC external power supply to a constant level and uses the output drive voltage as the drive power source for the control circuit. Since the arc machining apparatus is configured to be supplied with the electric current, the configuration can be simplified, and the transformer required for the control circuit can be downsized, so that the arc machining apparatus as a whole can be made smaller and lighter, and can be provided at a lower cost.

[Brief explanation of the drawing]

Figure 1 is a basic configuration diagram of the device of the present invention, Figure 2 is a specific block diagram, Figure 3 is an example diagram of the internal circuit of the automatic input voltage switching circuit, and Figures 4 and 5 are automatic input voltage switching circuits. Time chart explaining the operation of the circuit,
FIG. 6 shows another example of the internal circuit of the automatic input voltage switching circuit. Explanation of symbols, 1... Voltage adjustment circuit, 2... Inverter drive section, 3... Control section, 31... DC-DC
converter, 32...control circuit, 4...input voltage automatic switching circuit, 5...output section.

Claims (1)

[Scope of utility model registration request] It has a voltage discrimination circuit that discriminates between the types of AC external power supplies with two different voltage levels, and an input voltage automatic switching circuit that outputs a switching signal when it determines that the external power supply voltage is at the lower level voltage, and this input voltage. Depending on the switching signal from the automatic voltage switching circuit,
A voltage adjustment circuit that converts and outputs an input external power supply into a DC drive voltage at a constant level by switching control, and a voltage adjustment circuit that receives the DC drive voltage at a constant level output from this voltage adjustment circuit. It has an inverter drive section that operates with a constant level of direct current from the voltage adjustment circuit, an output section that supplies the output from the inverter drive section to the load, and an output detector that detects the output supplied to the load. and a control unit that receives the converted drive voltage, supplies drive power to a control circuit via a DC-DC converter, and outputs a control signal from the control circuit to the inverter drive unit, and the control unit receives the input voltage automatically. When the voltage discrimination circuit of the switching circuit determines that the external power supply is at the lower voltage level, it outputs a switching signal after a predetermined delay time has elapsed to cause the voltage adjustment circuit to change the external power supply voltage. Arc machining equipment that can automatically switch settings depending on the type.